Compact satellite-enabled seismic sensor node

Abstract

Embodiments relate generally to a data acquisition unit for performing passive seismic monitoring. An example data acquisition unit includes: a housing including an upper part and a lower part, the lower part including a vibration sensing portion for sensing vibration in a ground region, and the upper part and lower part together defining a central chamber; a vibration transducer configured to receive vibrations via the vibration sensing portion and generate an output signal based on the received vibrations; a processing unit configured to receive and process the output signal to generate one or more data payloads; a component mounting structure received in the chamber and coupled to the housing. The unit includes a satellite modem disposed at a top portion of the housing. The satellite modem is configured to receive one or more generated payloads from the processing unit and transmit the one or more generated payloads to a satellite.

Description

"Compact satellite-enabled seismic sensor node"Technical Field

[0001] Embodiments relate to data acquisition units or nodes and more specifically to seismic data acquisition units or nodes for use in data gathering for ambient noise tomography (ANT). Some embodiments relate to a method for data acquisition, and systems employing one or more data acquisition units. Some embodiments relate to systems comprising one or more data acquisition units in communication with a remote server, for remote processing of passively monitored seismic data for creating subsurface tomography images accessible to client devices.Background

[0002] Data acquisition for ambient noise tomography processing can be a timeconsuming endeavour. Ambient noise tomography requires continuous sampling. There may be significant latency from deploying data acquisition sensors and subsequently collecting the data measured from the data acquisition sensors to producing ambient noise tomography images, which can take from several weeks to several months.Furthermore, the data acquisition sensors for ambient noise tomography may need to be deployed in remote and / or harsh environments which can present various challenges. In remote and harsh environments without a power supply, there may be data storage and power constraints associated with data acquisition for ambient noise tomography. Data acquisition units for ambient noise tomography may be difficult and / or time consuming to deploy. Deployment of data acquisition units may be expensive, particularly when scaling to arrays of data acquisition units for ambient noise tomography, so gains in efficiency of deployment and data harvesting can result in cost savings.

[0003] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[0004] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.Summary

[0005] Some embodiments relate to a data acquisition unit for performing passive seismic monitoring, the data acquisition unit including: a housing including an upper part and a lower part, the lower part including a vibration sensing portion for sensing vibration in a ground region, and the upper part and lower part together defining a central chamber; a vibration transducer configured to receive vibrations via the vibration sensing portion and generate an output signal based on the received vibrations; a processing unit configured to receive and process the output signal to generate one or more data pay loads; a synchronisation unit including an antenna, wherein the synchronisation unit is configured to receive a synchronisation signal from a satellite via the antenna and to communicate synchronisation data to the processing unit based on the synchronisation signal; a power source to provide power to the processing unit and synchronisation unit; a component mounting structure received in the chamber and coupled to the housing, the processing unit and the synchronisation unit are coupled to and carried by the component mounting structure, the power source coupled to and received by the component mounting structure; and a satellite modem disposed at a top portion of the housing, wherein the satellite modem is configured to receive one or more generated payloads from the processing unit and transmit the one or more generated payloads to a second satellite.

[0006] The component mounting structure may be attached to the upper part via fasteners, so that, when assembling, the upper part may be positioned upside down when attaching the component mounting structure, when mounting electronics to the component mounting structure, when wiring the electronics and the modem, and / orwhen attaching the lower part to the upper part to house the component mounting structure.

[0007] The component mounting structure may comprise outer side faces for mounting one or more printed circuit board (PCB) assemblies, the one or more PCBAs configured for bearing the processing unit and the synchronisation unit.

[0008] According to some embodiments, the data acquisition unit further includes two PCBAs bearing the processing unit and the synchronisation unit, the two PCBAs mounted on opposite outer side faces of the component mounting structure.

[0009] According to some embodiments, the component mounting structure comprises multiple pieces. The component mounting structure may have a lower compartment for carrying the power source. The component mounting structure may be a unitary structure. The component mounting structure may comprise a single u-shaped piece.

[0010] According to some embodiments, the lower part includes a protruding structure into the central chamber, the protruding structure including a recess into the vibration sensing portion, the recess configured to hold the vibration transducer.

[0011] According to some embodiments, one or more lower outer portions of the component mounting structure include extending flanges which contact and stabilise the component mounting structure to the lower part, and wherein the extending flanges space an inner lower portion of the component mounting structure from the lower part, so that the inner lower portion of the component mounting structure is above or in contact with the held vibration transducer and / or the protruding structure.

[0012] According to some embodiments of the present disclosure, the data acquisition unit further comprises one or more antenna mounts on the inside of the upper part for attaching the antenna in the central chamber. The antenna may be a monopole antenna, and the one or more antenna mounts may each comprise a ring to suspend the antenna.

[0013] According to some other embodiments, the data acquisition unit further comprises an antenna mount on the component mounting structure for attaching the antenna. The component mounting structure may comprise a top compartment, and the antenna mount may be configured for attaching the antenna within the top compartment. The upper part of the housing may comprise a first modem port and the top compartment of the component mounting structure may comprise a second modem port, so that the satellite modem can be communicatively coupled to the processing unit via a cable and the first and second modem ports. The antenna may be a monopole antenna. The antenna mount may be configured for attaching the antenna horizontally, perpendicular to a longitudinal axis.

[0014] In some embodiments, the satellite modem includes a satellite communication antenna, the satellite modem is configured to transmit the one or more generated payloads to the second satellite via the satellite communications antenna, optionally the satellite modem is self-contained within a second housing, optionally the second housing having an ingress protection (IP) rating of at least 67.

[0015] The satellite modem may consume about 9.6 to 9.8 Wh in a day, based on a transmission duty cycle of about 2% and reception duty cycle of about 12.5%.

[0016] According to some embodiments, the processing unit and / or the satellite modem is configured to transmit about 100 kilobytes to 450 kilobytes of one or more payloads per day to the second satellite.

[0017] The processing unit and / or satellite modem is configured to transmits the one or more payloads per day to the satellite modem on a randomised scheduled timing with an average transmission time interval (TTI) of about 10 to 30 seconds.

[0018] The upper part and lower part may be formed using Polycarbonate (PC) and acrylonitrile butadiene styrene (ABS).

[0019] According to some embodiments, the power source has a mass between about 500 grams to about 1200 grams and the data acquisition unit has a mass between about 2190 grams to about 3375 grams.

[0020] According to some embodiments, the vibration sensing portion is formed using Polycarbonate (PC) and acrylonitrile butadiene styrene (ABS). The vibration sensing portion may be integrally formed with the lower part.

[0021] According to some embodiments, the upper part is between about 140 mm to 250 mm in diameter. In some embodiments, the lower part is between about 140 mm to 250 mm in diameter.

[0022] According to some embodiments, the power source has dimensions between about 72 mm to 80 mm in width, 68 mm to 76 mm in length, and 110 to 118 mm in height. In some embodiments, the component mounting structure has dimensions between about 68 to 90 mm in width, 68 mm to 90 mm in length, and 110 mm to 150mm in height.

[0023] According to some embodiments, the power source has an energy storage capacity between about 85 Wh and 285 Wh. In some embodiments, the power source has an energy storage capacity between about 240 Wh and 285 Wh. The power source may be a 24-cell battery.

[0024] According to some embodiments, the satellite modem is at least one of: encased in the housing; or attached to a mounting portion of the upper part. The upper part mounting portion may define a recess to receive the satellite modem therein.

[0025] Some embodiments relate to a method of data acquisition performed by a data acquisition system, the data acquisition system including multiple ones of the data acquisition units according to some embodiments of the present disclosure, the method comprising: positioning the multiple data acquisition units at spaced surface locations across a ground region; and operating each of the data acquisition units to receivevibrations over a plurality of days; wherein the data acquisition units are operable to generate and send processed data based on vibrations received by the one or more data acquisition units at the spaced surface locations.

[0026] In some embodiments, the operating includes continuous operation of the one or more data acquisition units to receive vibrations and generate the processed data.

[0027] In some embodiments, the operating includes continuous operation of the one or more data acquisition units to receive vibrations and generate the processed data for a period of between 4 and 10 days, wherein a power supply or power source of each of the one or more data acquisition units is contained within the housing of each of the one or more data acquisition units and is configured to supply power for operation of the respective data acquisition unit for more than 10 days.

[0028] According to some embodiments, the data acquisition system includes one or more satellites, one or more ground stations, and a server system. The one or more data acquisition units may be operable to generate and send the processed data, via the one or more satellites and one or more ground stations, to a server system for performing computed tomography of the subsurface of the ground region.

[0029] Some embodiments of the present disclosure relate to a data acquisition unit for performing passive seismic monitoring, the data acquisition unit including: a first housing defining a central chamber; a vibration transducer in the housing, the vibration transducer configured to receive vibrations via the housing and generate an output signal based on the received vibrations; a processing unit configured to receive and process the output signal to generate one or more data pay loads; a synchronisation unit including an antenna, wherein the synchronisation unit is configured to receive a synchronisation signal from a first satellite via the antenna and to communicate synchronisation data to the processing unit based on the synchronisation signal; a power source to provide power to the processing unit and synchronisation unit; a satellite modem disposed inside the first housing, wherein the satellite modem isconfigured to receive one or more generated payloads from the processing unit and transmit the one or more generated payloads to a second satellite.

[0030] Some embodiments of the present disclosure relate to a data acquisition unit for performing passive seismic monitoring, the data acquisition unit including: a first housing defining a central chamber; a vibration transducer in the housing, the vibration transducer configured to receive vibrations via the housing and generate an output signal based on the received vibrations; a processing unit configured to receive and process the output signal to generate one or more data pay loads; a synchronisation unit including an antenna, wherein the synchronisation unit is configured to receive a synchronisation signal from a satellite via the antenna and to communicate synchronisation data to the processing unit based on the synchronisation signal; a power source to provide power to the processing unit and synchronisation unit; and a ground plane for mounting a satellite modem, the ground plane received in the central chamber.

[0031] Some embodiments of the present disclosure relate to a data acquisition unit for performing passive seismic monitoring, the data acquisition unit including: a first housing defining a central chamber; a vibration transducer in the housing, the vibration transducer configured to receive vibrations via the housing and generate an output signal based on the received vibrations; a processing unit configured to receive and process the output signal to generate one or more data pay loads; a synchronisation unit including an antenna, wherein the synchronisation unit is configured to receive a synchronisation signal from a satellite via the antenna and to communicate synchronisation data to the processing unit based on the synchronisation signal; a power source to provide power to the processing unit and synchronisation unit; and a component mounting structure for mounting a satellite modem, the component mounting structure received in the central chamber and coupled to the first housing.

[0032] The first housing may include an upper part and a lower part, the upper part and lower part together defining the central chamber.

[0033] The data acquisition unit may further include a component mounting structure received in the central chamber and coupled to the first housing. The component mounting structure may comprise a second housing with an internal chamber, the second housing receiving the power source in the internal chamber. In some embodiments, the component mounting structure is attached to the upper part of the first housing. The processing unit and the synchronisation unit may be coupled to and carried by the component mounting structure. The component mounting structure comprises outer side faces for mounting one or more printed circuit board assemblies (PCBAs), the one or more PCBAs configured for including the processing unit and the synchronisation unit.

[0034] In some embodiments, the lower part of the first housing includes a protruding structure that protrudes into the central chamber, the protruding structure including a recess into the lower part, the recess configured to hold the vibration transducer. The protruding structure may include a plurality of internal ribs configured to be compressed by insertion of the vibration transducer into the recess so that the protruding structure can securely hold the vibration transducer.

[0035] The component mounting structure may include two printed circuit board assemblies (PCBAs) wherein at least one PCBA of the two PCBAs is configured to include the processing unit and the synchronisation unit, the two PCBAs mounted on two opposite outer side faces of the component mounting structure. A first printed circuit board assembly (PCBA) may be disposed inside the housing and include the processing unit and the synchronisation unit. In some embodiments, two opposite outer side faces vertically extend below a central underside portion of the second housing so that, when assembled, the second housing forms a cavity for covering the protruding structure. The two PCBAs may vertically extend below a central underside portion of the second housing.

[0036] The data acquisition unit may further include an electromagnetic shielding structure enclosing the first PCBA.

[0037] In some embodiments, the data acquisition unit further includes a ground plane, wherein the satellite modem is coupled to the ground plane. In some embodiments, the satellite modem is mounted to the ground plane. In some embodiments, the ground plane is coupled to the component mounting structure.

[0038] The ground plane may include indentations along one or more edges of the ground plane to permit passage of cabling from a first space above the ground plane to a second space below the ground plane. The antenna may be mounted to the ground plane.

[0039] In some embodiments, the lower part is free of a vibration sensing projection or spike extending from the housing. The lower part may include a plurality of radially projecting ribs on an internal floor of the lower part.

[0040] In some embodiments, the ground plane separates a first space above the ground plane containing the satellite modem and a second space below the ground plane containing the processor and synchronisation unit. The ground plane may substantially extend a horizontal cross-section of the internal chamber of the first housing. The ground plane may be coupled to the component mounting structure.

[0041] In some embodiments, the ground plane includes indentations along one or more edges of the ground plane to permit passage of cabling from the first space to the second space.

[0042] In some embodiments, the ground plane is located at a vertical location in the central chamber in horizontal alignment or approximate alignment to: a vertical location of connecting regions of the upper part and the lower part and / or a vertical location of a lowermost located peripheral component of the upper part. This may allow data acquisition unit to be suitably buried so that the surface of the soil surrounding the housing functions at least somewhat as a further (or extended) reflecting ground plane for enhancing the radio communications of the satellite modem inside the housing.Brief Description of Drawings

[0043] Figure 1 is a block diagram of a sub-surface tomography system according to some embodiments.

[0044] Figure 2 shows an exploded view of data acquisition unit according to some embodiments.

[0045] Figure 3 shows an external perspective view of data acquisition unit according to some embodiments.

[0046] Figure 4 shows a perspective view of the modem, electronics and upper part of data acquisition unit during assembly according to some embodiments.

[0047] Figure 5 shows an exploded view of the modem, component mounting structure, electronics and upper part of data acquisition unit according to some embodiments.

[0048] Figure 6A shows a perspective view of the component mounting structure of data acquisition unit bearing electronics according to some embodiments.

[0049] Figure 6B shows, within a semi-transparent view of upper part of data acquisition unit, a perspective view of the component mounting structure of data acquisition unit bearing electronics while attached to upper part according to some other embodiments.

[0050] Figure 7 shows a perspective view of the underside of satellite modem according to some embodiments.

[0051] Figure 8 shows an exploded view of the vibration transducer, component mounting structure platform, and lower part of data acquisition unit according to some embodiments.

[0052] Figure 9 shows a cross-sectional view of the vibration transducer, component mounting structure platform, and lower part of data acquisition unit according to some embodiments.

[0053] Figure 10 shows a cross-sectional view of the lower part of data acquisition unit according to some embodiments.

[0054] Figure 11 shows an exploded view of data acquisition unit according to some embodiments.

[0055] Figure 12 shows a cross-sectional view of data acquisition unit according to some embodiments.

[0056] Figure 13 shows data acquisition unit when deployed in the field according to some embodiments.

[0057] Figures 14A and 14B shows printed circuit board assemblies of data acquisition unit according to some embodiments.

[0058] Figures 15 A, 15B, and 15C show sub-surface imaging according to some embodiments.

[0059] Figure 16 shows sub-surface imaging according to some embodiments.

[0060] Figures 17 A and 17B show schematic diagrams of electronic components of data acquisition unit according to some embodiments.

[0061] Figure 18 shows an example computer system.

[0062] Figure 19 shows a cross-sectional view of data acquisition unit according to some embodiments.

[0063] Figure 20 shows an exploded view of a data acquisition unit according to some embodiments.

[0064] Figure 21 shows a perspective view of a data acquisition unit according to some embodiments.

[0065] Figure 22 shows a side view of a data acquisition unit according to some embodiments.

[0066] Figure 23 shows an overhead view of a data acquisition unit according to some embodiments.

[0067] Figure 24A shows a perspective view from above the component mounting structure of a data acquisition unit bearing electronics and a satellite modem according to some embodiments.

[0068] Figure 24B shows a perspective view from below the component mounting structure of a data acquisition unit bearing electronics according to some embodiments.

[0069] Figure 25 shows a perspective view of the underside of the upper part of a data acquisition unit according to some embodiments.

[0070] Figure 26 shows a perspective view of the component mounting structure, electronics and upper part of a data acquisition unit during assembly according to some embodiments.

[0071] Figure 27 shows a perspective view of an antenna ground plane according to some embodiments.

[0072] Figure 28 shows an isometric view of a modem mounted on the ground plane according to some embodiments.

[0073] Figure 29 shows an exploded view of the modem, component mounting structure, and electronics of data acquisition unit according to some embodiments.

[0074] Figure 30 shows an overhead view of the lower part of data acquisition unit according to some embodiments.

[0075] Figure 31 shows a cross-sectional view of lower part of data acquisition unit according to some embodiments.

[0076] Figure 32 shows a perspective cross-sectional view of data acquisition unit according to some embodiments.Description of Embodiments

[0077] Embodiments relate to data acquisition units and more specifically to seismic data acquisition units for use in ambient noise tomography (ANT). Some embodiments relate to a method for data acquisition, and systems employing one or more data acquisition units. Some embodiments relate to systems comprising one or more satellites in communication with one or more data acquisition units for communication to a remote server, for remote storage and processing for creating sub-surface tomography images accessible to client devices. The sub-surface tomography images may be ambient noise tomography images created from ambient noise tomography processing.

[0078] The data acquisition unit may be configured to sense vibrations in a ground area / region. The data acquisition unit may include a vibration transducer, such as a geophone. The vibration transducer is configured to convert sensed vibrations into an electrical signal. The data acquisition unit may include an analogue to digital converter, which may digitise the electrical signal. The data acquisition unit may include a processor which may pre-process the (digitised) electrical signal and process the pre- processed electrical signal into a data pay load. The data acquisition unit may include a satellite modem that is configured to transmit the data payload to a satellite. Thesefeatures are similar to those described in pending Australian patent application 2022209325 which this present specification incorporates entirely by reference.

[0079] The data acquisition units may be self-contained. The data acquisition units may be relatively compact. The data acquisition units may be easily deployed, redeployed, and / or removed due to their small form factor and low mass. The data acquisition units may be easily assembled and / or disassembled. The data acquisition units may be relatively economical for manufacturing. The data acquisition unit may house all utilised antennas, and therefore may mitigate or reduce one or more of: vandalism, the number of failure points, wear, and effects of weather. The data acquisition unit may have limited points of ingress, and thereby may better resist the effects of weather and debris. The data acquisition unit may utilise paint coatings selected to resist effects of extreme temperature. The data acquisition unit may utilise electronic components which help resist effects of extreme temperature. The internal physical layout of the data acquisition unit may help resist or mitigate negative functional effects of extreme temperature. The housing and / or components of data acquisition unit may comprise materials that may help resist the effects of extreme temperature. The data acquisition unit may utilise insulated cabling from the geophone, and this may assist in reducing the internal noise of the data acquisition unit. The data acquisition unit may have a cable length from the geophone to a PCBA that carries an analogue to digital converter of about 10 to 30 cm, for example. This limited cable length may assist in reducing the internal noise of the data acquisition unit.

[0080] According to some embodiments, the data acquisition units may be capable of direct radio communications with a low earth orbit (LEO) satellite network. In some other embodiments, the data acquisition unit may be capable of direct radio communication with a geostationary satellite and / or geostationary satellite network. The data acquisition units may be capable acquiring ground movement measurements, processing the measurement data, transmitting the data via the LEO satellite network to be received by a server system for ambient noise tomography processing in about 2 minutes to 2 hours depending on satellite availability, immediately after the data acquisition unit is deployed. Thus, the embodiments allow near-real time reception ofdata from the data acquisition units, for example for ambient noise tomography purposes. In this context of geological feature observation (i.e. long time scale as opposed to high-speed computing), near-real time is intended to include periods of as low as around 1-2 minutes latency up to around 2-4 hours or 6-12 hours latency from vibration sensing to reception at the remote server. This allows images to be formed at remote client computing devices from the ambient noise tomography within a matter of days, such as around 4 days, as the received data accumulates to provide a higher and higher resolution image.

[0081] As soon as a data acquisition unit is placed, the unit can be turned on and operated so that ambient noise tomography processing can commence whilst other data acquisition units are added to the array of data acquisition units for imaging a subsurface region according to some embodiments. The imaging and the sub-surface region which is imaged may be three dimensional (3D).

[0082] Ambient noise tomography images according to some embodiments may be available for viewing on a client device communicatively coupled to the server system within 24 hours (for low resolution) and more substantial (higher resolution) images within 4 to 5 days. The resolution and information richness of the ambient noise tomography images may be iteratively improved upon subsequent sampling and transmission of data from the data acquisition units over the sampling period of 4 to 10 days or 2 to 8 days, for example.

[0083] According to some embodiments the data acquisition units may be self- contained and include a ground sensing module, processor, memory, a power source, and an attachable satellite communications module. The self-containment of the data acquisition units may allow ease of field deployment, field re-deployment, and transport of the data acquisition units. This may help attain cost and time reductions associated with the deployment and transport of data acquisition units. The self- contained data acquisition unit including ground sensing module, processor, memory, a power source, and an attachable satellite communications module may have a massbetween about 2 to 3 kgs, 3 to 4 kgs, or 4 to 5 kgs. In some embodiments, the self- contained data acquisition unit has a mass of about 5, 4.5, 4, 3.5, 3, 2.5, or 2 kgs.

[0084] In some embodiments, the data acquisition unit has a power consumption between about 19 to 24 Wh, and the satellite modem used by the data acquisition unit has a power consumption in a day of between about 9.6 to 9.8 Wh or about 0.4 to 0.41 W. In some embodiments, the data acquisition unit has a power consumption of about 21.4 Wh in a day. According to some embodiments, the other electronics of the data acquisition unit may have a power draw between about 0.4 to 0.5 W.

[0085] In some embodiments, the satellite modem has a standby power consumption between about 0.15 to 0.2 W. In some embodiments, the satellite modem has a standby power consumption of about 0.17 W. In some embodiments, the satellite modem used by the data acquisition unit has a standby power consumption in a day of between about 3 to 4.1 Wh. In some embodiments, the satellite modem used by the data acquisition unit has a standby power consumption in a day of about 3.5 Wh.

[0086] In some embodiments, the satellite modem has a transmission power consumption between about 7 to 7.5 W. In some embodiments, the satellite modem has a transmission power consumption of about 7.3 W. In some embodiments, the satellite modem has a transmission power consumption in a day between about 3 to 3.6 Wh. In some embodiments, the satellite modem has a transmission power consumption in a day of about 3.5 Wh.

[0087] In some embodiments, the satellite modem has a received signal processing power consumption between about 0.8 to 1 W. In some embodiments, the satellite modem has a received signal processing power consumption of about 0.9 W. In some embodiments, the satellite modem has a received signal processing power consumption between about 2.7 to 2.8 Wh. In some embodiments, the satellite modem has a received signal processing power consumption of about 2.72 Wh.

[0088] In some other embodiments, alterations such as the selection of a modem with an average power consumption of about 0.26W, may reduce the power consumption of the data acquisition unit to less than 7 W, which may extend this timeframe to 11 days without any further (external) power source, for example. The operating temperature also may vary the operation time of the data acquisition unit without any further (external) power source. In temperatures less than 20 degrees Celsius, the data acquisition unit may operate for 7 days without any further (external) power source. The operation times of the data acquisition unit, without any further (external) power source, may be based on time between transmission peaks of about every 15 to 20 minutes, for example.

[0089] In some embodiments, the data acquisition unit is configured to transmit data payloads to the server system in transmission intervals over a day of a combined transmission time between about 25 to 30 minutes. In some embodiments, the transmission duty cycle may be about 2%. In some embodiments, the data acquisition unit is configured to transmit data payloads to server system with an average transmission time interval between about 10 minutes to 4 hours. In some embodiments, data acquisition unit is configured to transmit consecutive data payloads with an average transmission time interval between about 10 minutes to 30 minutes. In some embodiments, data acquisition unit is configured to transmit consecutive data payloads with an average transmission time interval of about 10 minutes, 13 minutes, 16 minutes, 20 minutes 23 minutes, 26 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 3 hours, or about 4 hours.

[0090] In some embodiments, the data acquisition unit is configured to receive data transmissions over scheduled and / or unscheduled reception intervals in a day of a combined reception time between about 180 minutes to 200 minutes. In some embodiments, the reception duty cycle may be about 12.5%. In some embodiments, the data acquisition unit may be in standby when satellite modem is not transmitting or receiving data. In some embodiments, the data acquisition unit is configured to be in standby over scheduled and / or unscheduled intervals in a day for a combined standby time between about 20 to 22 hours.

[0091] According to some embodiments, the pay load size may be between about 2kB to 40 kB. According to some embodiments, the pay load size may be about 2 kB or 4 kB.

[0092] The data acquisition unit may process and store sampled pre-processed data locally and then transmit the data. The transmission of this stored data may represent a transmission peak. This time between peaks may be referred to as a duty cycle.

[0093] The power source to reach the above operation times of the data acquisition unit without any further (external) power source may be about 580 to 600 Wh. In some embodiments, a lower capacity power source may be selected to achieve smaller durations of operation without any further (external) power source. For example, the data acquisition unit may be configured with a modem with average power consumption of about 0.45 W and a power source of about 81.5 Wh capacity to achieve 4 days of operation without any further (external) power source. In another example, the data acquisition unit may be configured with a modem with average power consumption of about 1.0 W and a power source of about 157.5 Wh capacity to achieve 4 days of operation without any further (external) power source. In another example, the data acquisition unit may be configured with a modem with average power consumption of about 0.45 W and a power source of about 163 Wh capacity to achieve consecutive periods of 4 days of operation (8 days of operation total) without any further (external) power source. In another example, the data acquisition unit may be configured with a modem with average power consumption of about 1.0 W and a power source of about 315 Wh capacity to achieve consecutive periods of 4 days of operation (8 days of operation total) without any further (external) power source.

[0094] The power, storage, and transmission requirements of this operation may be aided by preprocessing the acquired data (to drastically compress the data by 8: 1 or 16: 1 or 32: 1, for example) from the ground sensing module. The power source may be or include a rechargeable battery pack, for example.

[0095] According to some embodiments, the data acquisition unit measures seismic vibration in the ground region near where it is deployed. A geophone element may be used to generate electrical signals proportional to the vibrational velocity induced in the sensor. This signal is digitised and stored in a data buffer. Ambient noise tomography usually requires a continuous stream of data. In addition, only the z-axis (coaxial with the local gravity vector) may be required. The data acquisition unit may sample its single geophone every 50 milliseconds (20 Hz), for example. It may store each sample in a software buffer. This sample rate could be higher, but as will become clear, the higher the sample rate, the greater the processing capability (and non-volatile storage) needs to be. The samples buffer may have a size to be able to hold 512 samples, for example. In some other embodiments, the buffer size may be 64, 128, 256, 512, or 1024 samples. Once the current buffer is full, the buffer contents is passed down into a sequence of digital signal processing functions. Whilst this processing is happening (taking up computer resources), new samples obtained from the geophone are inserted into a second buffer. As such, between these two buffers, one will always be used for the processing algorithms and the other will be used to receive new samples.

[0096] According to some embodiments, the digital signal pre-processing includes six stages. The fundamental purpose of these pre-processing algorithms is to condition the data for seismic analysis and reduce the data size significantly. The first stage may optionally decimate the data. The second stage de-trends or de -biases the data. This is intended to remove inherent biases in the geophone signal (such as a DC bias or temperature influence). The third pre-processing stage uses a fast Fourier transform (FFT) algorithm to convert the time-domain seismic signal into its frequency constituents. This FFT algorithm requires the data buffer size to be an exponent factor of two. With the data in the frequency domain, the signal can be filtered by applying pre-determined filter coefficients or making changes to the amplitude and frequency bins. The fourth pre-processing stage spectrally whitens the filtered data. By whitening the data, the amplitude across a frequency range can be essentially normalised with a Tukey window. The rounded edges are intended to reduce any aliasing (artefacts) when transforming the filtered data back into the time domain. The fifth pre-processing stage does this transformation by using the inverse fast Fourier transform (IFFT) algorithm.The sixth and final pre-processing stage of this processing pipeline includes one -bit normalising the data. With one-bit normalising, amplitudes that are positive are represented with a one, and conversely amplitudes that are negative are represented with a zero. Even though the amplitude information of the original seismic signal is essentially obliterated, the phase information of the signal is preserved. The phase information may be more helpful or essential than the amplitude information for processing ambient noise tomography at the server system where the data is used to generate three-dimensional subsurface models.

[0097] The one -bit normalisation may compress the data substantially, allowing the original four-byte sample (from a 32-bit analogue to digital converter) to be represented by a single bit (e.g., 32: 1 compression ratio). From the perspective of a payload that can be sent from the data acquisition unit via the satellite modem, each byte will contain eight samples. In other embodiments, a lesser compression ratio, such as 8: 1 or a compression ratio between 8: 1 and 32: 1, may be used.

[0098] The housing may be secured into the ground and rotation-limiting portions, such as radial buttresses or ribs, may project from an underside of the housing (e.g., extending between the outer wall and an upper part of the sensor probe housing part) to mitigate or resist rotation of the housing or the sensing probe. This assists to mitigate errors due to changing device orientation, for example. The housing may have two printed circuit boards (PCBs), each mounting components of the data acquisition unit to form respective printed circuit board assemblies (PCBAs), to improve the configuration of cabling within the housing.

[0099] The housing may contain a synchronisation antenna. The modem may have a housing containing its antenna. Therefore, the unit may not have any exposed antennas, to reduce the likelihood of damage to the unit and antenna. The unit may have a small form factor for easy packing and charging on a charging rack. In some embodiments, at least one of the data acquisition units may be placed in a charging case for charging.The charging case can be used for transporting the at least one of the data acquisitionunits to or from a site before, between, or after deployments. Transport can be by a vehicle, such as a ground, air, or aquatic based transport vehicle.

[0100] The housing may contain a component mounting structure. The component mounting structure may be used to mount one or more PCBAs containing electronics such as the processor. The component mounting structure may be used to receive the power source. The component mounting structure may be attached to an upper part of the data acquisition unit bearing the satellite modem. This attachment may allow an assembler / operator to easily cable the power source, electronics, and modem before sealing the unit. This advantage may further be realised by assembling the modem, upper part, and / or component mounting structure together upside down to the unit’s operational orientation and / or by cabling the power source, electronics, and modem when the attached modem, upper part, and component mounting structure are oriented upside down to the unit’s operational orientation.

[0101] According to some embodiments of the present disclosure, the data acquisition unit design may include at least one of: plastic top part, plastic bottom part, plastic vibration sensing portion, a cradle for mounting electronics and power source to reduce the required internal volume of the housing, no internal integration columns, or a smaller form factor, which is more economical for manufacturing than at least some prior ANT data acquisition units, for example as described in some embodiments of Australian patent application 2022209325. According to some embodiments of the present disclosure, the data acquisition unit design may be lighter and / or more compact than at least some prior ANT data acquisition units, for example such as described in some embodiments of Australian application 2022209325. According to some embodiments of the present disclosure, the data acquisition unit design may reduce assembly, disassembly, deployment, redeployment, and removal times when compared with at least some prior ANT data acquisition units, for example as described in some embodiments of Australian application 2022209325.

[0102] According to some embodiments, the inclusion of a component mounting structure may allow easy assembly, disassembly and cleaning of the interior of thehousing. According to some embodiments, the design including the component mounting structure may allow easy cleaning of the two PCBAs by providing an easily withdrawable mounting structure from which each PCBA can be manually detachable and re-attachable.

[0103] According to some embodiments, the positioning of the antenna within the housing of the data acquisition unit may reduce the number of exposed parts and thereby may reduce vandalism, wear, and effects of weather. According to some embodiments, the data acquisition unit may be designed to resist the effects of weather and temperature.

[0104] Operational orientation may be a term used in the present disclosure to denote the orientation or alignment of the data acquisition unit suitable for it to collect seismic measurements. The upper part may be located above the vibration sensing portion of the data acquisition unit when the data acquisition unit is in operation orientation. Operational orientation may necessitate that the upper part is above the vibration sensing portion but operational orientation may not necessitate that the upper part is directly above the vibration sensing portion. Operational orientation may be when the vibration sensing portion is in contact with the ground surface or embedded in the ground surface sufficiently to sense vibrations and the satellite modem has a view of the sky to communicate with an orbiting satellite. Operational orientation may also be described as horizontal operational orientation.

[0105] Figure 1 is a block diagram of a sub-surface tomography system 100 according to some embodiments.

[0106] The sub-surface tomography system 100 may also be described as a data acquisition system 100. The sub-surface tomography system 100 comprises a data acquisition unit array 115. Data acquisition unit array 115 may also be referred to as data acquisition array 115, or array 115.The data acquisition array 115 comprises one or more data acquisition units 110. Data acquisition unit 110 may be configured for passive seismic monitoring. The data acquisition unit 110 may also be referred to as aseismic data acquisition unit 110, vibration sensing apparatus 110, seismometer module 110, geophone apparatus 110, geologic instrument 110, data acquisition node 110, endnode 110, node device 110 or a sensor node 110.

[0107] The sub-surface tomography system 100 also comprises a satellite constellation 135. The satellite constellation 135 comprises one or more satellites 130. Each of the one or more satellites 130 may be a Low Earth Orbit (LEO) satellite 130. In some other embodiments, one or more of satellites 130 may be a Geostationary (GEO) satellite 130. The satellite 130 is capable of communicating with data acquisition unit 110 over a communication link 118. In embodiments with more than one satellite 130, the communication link 118 may extend to the more than one satellite 130. The communication link 118 may not be a persistent communication link and if satellite 130 is not accessible to the data acquisition unit 110, the data acquisition unit 110 may await the resumption of the radio communication link 118 to continue communication of information.

[0108] Radio communication links 118 are radio links to satellites 130 orbiting the earth to communicate data acquired from the one or more data acquisition units 110 of the data acquisition array 115 and receive instructions or configuration information or firmware updates for the one or more seismic data acquisition units 110.

[0109] The sub-surface tomography system 100 also comprises one or more ground stations 140. The ground stations 140 receive communication from one or more satellites 130 of the satellite constellation 135 over a communication link 138.Communication link 138 may be referred to as ground station communications link 138. The communication link 138 may be facilitated by radio waves of suitable frequency according to the region where the ground station 140 is located.

[0110] The satellite 130 may be a LEO satellite that circles the earth approximately every 90-110 minutes, for example. With such orbiting satellites, a relatively smaller number of satellite ground stations 140 may be used to receive downlinks from satellite130, or all the data transmitted by the one or more data acquisition units 110 of the data acquisition array 115.

[0111] In some embodiments, satellites 130 in a near polar orbit may be used and ground stations 140 may be located near each of the Earth’s poles. This arrangement allows each satellite 130 to connect to a ground station 140 on almost every orbit, leaving the throughput latency no higher than around 45 minutes (half the time required to complete an orbit), for example. In some embodiments, ground stations may be located at lower latitudes with less harsh weather and transport, and easier access to power and communication links to the ground station 140. The ground station 140 may comprise radio communication equipment necessary to communicate with the satellite 130 and a communication interface to relay received information to a server system 150 over a communications link 148. Communication link 148 may also be referred to as server system communications link 148. The communication link 148 may be a wired or wireless communication link to the internet available to the ground station 140 and to the server system 150. The server system 150 may be accessible over the internet through an application or platform on a client device 160 over a conventional internet connection over the communication link 157. Client device 160 may be referred to as client computing device 160. Communication link 157 may be referred as client device communications link 157. The communications of server system 150 may be handled by a server system communications module. The client device 160 may be an end user computing device such as a desktop, laptop, mobile device, tablet, for example.

[0112] Diagnostic information may also be communicated from data acquisition unit 110 via satellite 130 to server system 150, which may be accessible to client device 160. Client device 160 may be configured to have an application to visualize the diagnostic information of one or more data acquisition units 110. In some embodiments, some or all of this diagnostic information is collected and sent by data acquisition unit 110 periodically. In some embodiments, some or all of this diagnostic information is collected and sent by data acquisition unit 110 upon an event such as upon connection / re-connection of link 118. In some embodiments, client device 160 is configured to send a request via server system 150, ground station 140, and satellite130 to data acquisition unit 110 to trigger the transmission (and optionally acquisition) of diagnostic information to server system 150, for access by client device 160.

[0113] The server system 150 may be configured to decode, decrypt and / or decompress communications originating from the data acquisition units 110 and received over the communication links 118, 138 and 148 and store any data from the communications in data storage 152. In some other embodiments, the server system 150 may receive communications originating from the data acquisition units 110 and store any data from the communications in data storage 152.

[0114] In some embodiments, server system 150 may further comprise a tomography module 154 (which includes program code) executable by a processor of the server system 150 or the tomography module 154 may be located separately and communicatively coupled to the server system 150 via link 153. Tomography module 154 may also be referred to as subsurface imaging module 154, or ambient noise tomography (ANT) module 154, for example. When executed, tomography module 154 may read data from the communications originating from the data acquisition units stored in data storage 152. The tomography module 154 may perform sub-surface tomography processing using the read data from the data storage 152. The sub-surface tomography processing may comprise ambient noise tomography processing. After performing sub-surface tomography processing, the tomography module 154 may send the sub-surface tomography data via link 153 to be stored in data storage 152. Subsurface tomography data may be data that can be processed to generate one or more sub-surface tomography images. Sub-surface tomography data may be data that can be processed to generate one or more sub-surface tomography images, such as one or more 3-D sub-surface tomography images.

[0115] Server system 150 may comprise or have access to code for executing a data visualisation module 156. The data visualisation module 156 may be a platform accessible to client device 160. The data visualisation module 156 may read subsurface tomography data from data storage 152. The data visualization module 156 may be located separately and communicatively coupled to the server system 150 via link155. The data visualisation module 156 and / or client device 160 may process subsurface tomography data to generate sub-surface tomography images to be viewed on client device 160. The generated sub-surface tomography images may be ambient noise tomography images.

[0116] The sub-surface tomography system 100 enables high-latency communication of data between the data acquisition array 115 and the client device 160. High-latency communication may be inherently suitable for transmitting small messages to and from the data acquisition array 115 deployed in remote locations and the server system 150. High-latency communication may comprise a latency of greater than about 1 second, 2 seconds, 15 seconds, 30 seconds, or 1, 2, 3, 4 or 5 minutes, for example. Two high- latency communication methods are store and forward communication and short burst data communication.

[0117] Store and forward communication may be implemented by the satellite constellation 135 that periodically passes into a range where communication may be received from the data acquisition units 110 positioned in a remote location. Satellite 130 may gather data from the data acquisition units 110 and deliver it back to ground stations 140 that are connected to a network backbone or a network generally accessible over the internet. Short Burst Data (SBD) is another technique for communicating short data messages between seismic data acquisition unit 110 and a centralised host computing system such as the server system 150. SBD satellite messaging systems work by waiting for a suitable slot in a satellite network that has voice as its primary application. Examples include Orbcomm™, Iridium™ and Globalstar™. The voice traffic in such systems is prioritised and requires latencies typically less than 500 ms, for example. However, due to the fluctuating demands for voice traffic, there are windows in which shorter messages can be sent. This is analogous to the Short Messaging System (SMS) technique / standard used in terrestrial communications networks design for mobile telephony. The typical latencies of the SBD traffic in such systems can be in the range of 5 seconds to 10 minutes or greater, for example.

[0118] Figure 2 shows an exploded view of data acquisition unit 110 according to some embodiments. Data acquisition unit 110 is configured to acquire data for performing passive seismic monitoring, such as for ambient noise tomography processing. Data acquisition unit 110 may be configured to continuously acquire seismic data over a long period.

[0119] Data acquisition unit 110 includes a housing 220. The housing 220 may include an upper part 223. The housing 220 may include a lower part 226. The housing 220 includes a central chamber. In some embodiments, upper part 223 and lower part 226 define the central chamber. In some embodiments, upper part 223 and lower part 226 are attachable together to define the central chamber. Data acquisition unit 110 is self-contained when assembled.

[0120] Upper part 223 may include an upper part flange 225 protruding from a distal edge of the upper part 223. Lower part 226 may include a lower part flange 228 protruding from a distal edge of lower part 226.

[0121] Data acquisition unit 110 may include a satellite modem 290. Satellite modem 290 may be disposed at a top portion of the housing 220. The upper part 223 may comprise a satellite modem receiving portion 224 on an outer surface of upper part 223 for coupling, receiving, attaching, bearing, and / or including satellite modem 290. Satellite modem 290 may be referred to as satellite communications module 290. Satellite modem 290 may be a modem for communicating with one or more satellites 130 from satellite constellation 135. Accordingly, satellite modem 290 may be configured for low earth orbit (LEO) satellite communications. In some other embodiments, satellite modem 290 is configured for geostationary satellite communications. Satellite modem 290 may include a housing. Satellite modem 290 may be self-contained. The housing of satellite modem 290 may have an ingress protection (IP) rating of 67. Satellite modem 290 may include a processor. Satellite modem 290 may include an inbuilt-antenna. Satellite modem 290 may be an Orbcomm, Iridium, Fleet Space, Inmarsat, or Gilat modem, for example. Satellite modem 290 may be an Orbcomm ST2100. The satellite modem 290 may have a mass between about 350grams to 1 kg. According to some embodiments, the satellite modem may have a mass of about 400 grams.

[0122] Data acquisition unit 110 may include a satellite modem receiving portion 224, which in some embodiments may be a satellite modem receiving recess 224 and / or a satellite modem receiving feature 224, for receiving and / or mounting the satellite modem 290. The satellite modem receiving portion 224 and satellite modem receiving recess 224 may be located on a top surface of the upper part 223. The satellite modem receiving recess 224 may be 1 to 5 mm deep in the top surface of upper part 223. The satellite modem receiving portion 218 and satellite modem receiving recess 224 may have screw holes or other attachment features for securing satellite modem 290 to the top surface of the upper part 223 / data acquisition unit 110.

[0123] The data acquisition unit 110 may include a power supply. The power supply may include power supply circuitry and / or connections on / to components on a first printed circuit board assembly (PCBA) 250 and / or a second printed circuit board assembly (PCBA) 255. Data acquisition unit 110 may include a power source 240. The power supply may include power source 240. The power supply may supply power from power source 240 to components of data acquisition unit 110 via circuitry and / or connections to components on first PCBA 250 and / or second PCBA 255, such as processor 1484. The power supply may include a voltage / power regulator.

[0124] Data acquisition unit 110 may include a cable recess 229. Upper part 223 may include cable recess 229. Satellite modem receiving portion 224 may include cable recess 229. Cable recess 229 may allow cabling for data communications and / or power to / from the satellite modem 290 from / to modem recess 534, modem port 535, first PCBA 250, second PCBA 255, and / or power source 240, for example. In some other embodiments, data acquisition unit 110 includes a cable port 229. Upper part 223 may include cable port 229. Satellite modem receiving portion 224 may include cable port 229. Cable port 229 may allow cabling for data communications and / or power to / from the satellite modem 290 from / to modem recess 534, modem port 535, first PCBA 250, second PCBA 255, and / or power source 240, for example.

[0125] Data acquisition unit 110 includes a vibration sensing portion 227 for sensing vibrations in the ground area / region. Vibration sensing portion 227 may be a probe or spike, for example. In some embodiments, the lower part 226 includes the vibration sensing portion 227. Vibration sensing portion 227 includes a narrowing (generally conical) distal tip at a lower extremity of the vibration sensing portion 227.

[0126] Data acquisition unit includes a component mounting structure 230. The component mounting structure 230 includes a mounting body for mounting components thereon. The mounting body of the component mounting structure 230 may be a unitary structure. Alternatively, component mounting structure 230 may include multiple pieces coupled together to form the mounting body. The component mounting structure 230 may comprise a single part or piece. The mounting body may include multiple sides or panels. The mounting body may include multiple opposed sides or panels. The opposed sides or panels define mounting portions and / or mounting surfaces to which components, such as PCBAs, antennas, sensors, conductors and / or batteries (as non-limiting examples), can be mounted. The component mounting structure 230 may be, consist of or include a single u-shaped piece.

[0127] The component mounting structure 230 may include a plurality of sides, panels or faces. The sides, panels or faces define an interior volume and define at least one opening to a part of the component mounting structure 230 that is exterior to the interior volume. According to some embodiments, the component mounting structure 230 has a hollow approximately cuboid shape. According to some embodiments, the component mounting structure 230 is a hollow cuboid shape that is missing two opposite faces, for example as shown in Figure 2 and Figure 6A. According to some other embodiments, the component mounting structure 230 comprises three concatenated sides or faces, shaped as a u-shape, as shown in Figure 6B.

[0128] According to some embodiments, as shown in Figure 2, the mounting body and / or the faces or sides of component mounting structure 230 may comprise recesses, openings or passages for allowing cabling to extend between components mounted to the component mounting structure 230 and other internal and / or external components,such as satellite modem 290, externally accessible switch components and / or charging or communication ports. The recesses, openings or passages on component mounting structure 230 also serve to reduce the mass of the component mounting structure 230.

[0129] The component mounting structure 230 may be configured for receiving a power source 240 in the interior volume. Other embodiments of seismic data acquisition units described herein, such as those shown and described in relation to Figure 20, may use a power source 2240. Power source 240 may comprise at least one battery. Power source 240 may comprise one or more cells. Power source 240 may comprise a casing for one or more battery and / or storage cells. Power source 240 may comprise wiring between the one or more batteries and / or storage cells. Power source 240 may comprise a series and / or parallel arrangement of a plurality of storage cells. In some embodiments, power source 240 comprises 8 to 30 storage cells. In some embodiments, power source 240 comprises 3 series 3 parallel (3S3P) arrangement of storage cells. In some embodiments, power source 240 comprises 2S4P, 3S4P, 3S5P, 3S6P, 3S7P, 3S8P, 3S9P, or 3S10P arrangement of storage cells. In some embodiments, power source 240 comprises 3S8P arrangement of 24 storage cells. The arrangement of storage cells in series may be varied depending on the voltage requirements of the modem 290. The arrangement of storage cells may be varied depending on the individual cell voltage output for selected storage cells.

[0130] Power source 240 or 2240 may have an energy storage capacity between about 100 Wh to 1250 Wh, for example. In some embodiments, power source 240 or 2240 has an energy storage capacity of between about 85 Wh to 285 Wh, 240 Wh to 285 Wh, 100 Wh to 180 Wh, 150 Wh to 800 Wh, 150 Wh to 350 Wh, 300 Wh to 600 Wh, or 550 Wh to 800 Wh, for example. In some embodiments, power source 240 or 2240 may have an energy storage capacity of about 290 Wh at nominal voltage 10.8 V. In some embodiments, power source 240 or 2240 may have a minimum energy storage capacity of between about 100 Wh to about 140 Wh for continuous operation of about 4 to 5 days without any further (external) power source. This continuous operation time without any further (external) power source, may be dependent on modem 290 consuming about 0.17 W in standby, 0.9 W when receiving signals, and 7.3 W whentransmitting. This continuous operation time without any further (external) power source, may be dependent on a modem 290 which consumes up to about 9 to 10 Wh of power. In some other embodiments, power source 240 or 2240 has a maximum energy storage capacity of between about 1200 to 1250 Wh for continuous operation of about 60 days without any further (external) power source. In some embodiments, power source 240 or 2240 has an energy storage of about 280Wh for at least 9 days of continuous operation. In some embodiments, power source 240 or 2240 has an energy storage of about 280Wh for at least two deployment cycles, each deployment cycle having a duration for at least 4 days. This allows the data acquisition unit 110 or seismic data acquisition unit 2110 (shown and described in relation to Figure 20) to be used in one location for one deployment cycle of multiple days and then moved to another location for a second deployment cycle of multiple days.

[0131] In some embodiments, power source 240 or 2240 has an energy storage capacity of about 110 Wh to 150 Wh for continuous operation of about 4 to 5 days without any further (external) power source. In some embodiments, power source 240 or 2240 may have an energy storage capacity of between about 220 and 300 Wh for continuous operation of about 8 to 11 days without any further (external) power source. Such energy storage capacities may allow seismic data acquisition unit 110 or 2110 to acquire enough ground movement data in at least two different sites (i.e., deployed at one site for a period and then redeployed at another site for another period) for production of respective sub-surface images of the respective sub-surfaces of the sites. This continuous operation time without any further (external) charging or power source, may be dependent on a satellite modem 290 which consumes about or less than 0.6 W of power.

[0132] In some embodiments, power source 240 or 2240 has a capacity between about 260 Wh to 310 Wh for about 9 to 12 days of continuous operation. In some embodiments, power source 240 or 2240 has a capacity of about 280 Wh for about 9 to 10 days of continuous operation. In some embodiments, power source 240 or 2240 has a capacity of about 160 Wh to 220 Wh for about 7 days of continuous operation. Insome embodiments, power source 240 or 2240 has a capacity of about 215 Wh for about 7 days of continuous operation.

[0133] The component mounting structure 230 may be configured for mounting electronics. The component mounting structure 230 may include one or more panels on the exterior of component mounting structure 230 for mounting electronics. The component mounting structure 230 may be configured for mounting the first printed circuit board assembly (PCBA) 250. Component mounting structure 230 may mount first PCBA 250 on a first exterior panel of component mounting structure 230. The component mounting structure 230 may be configured for mounting a second PCBA 255. Component mounting structure 230 may mount second PCBA 255 on a second exterior panel of component mounting structure 230. In some other embodiments, the component mounting structure is configured for mounting one or more further PCBAs.

[0134] In some embodiments, the component mounting structure 230 is configured to mount the first PCBA 250 on one side of the component mounting structure 230, and also configured to mount the second PCBA 255 on the opposite side of the component mounting structure 230. When data acquisition unit 110 is assembled, first PCBA 250 may be cable connected to second PCBA 255. The use of component mounting structure 230 to contain power source 240 and mount at least one of: first PCBA 250 or second PCBA 255, helps realise an internal volume efficiency within the data acquisition unit 110.

[0135] The component mounting structure 230 may be received in the central chamber. The component mounting structure 230 may be configured to be attached to one or more inside portions of upper part 223. A top portion of component mounting structure 230 may include a recess for allowing cabling for data communications and / or power to / from the satellite modem 290.

[0136] In some other embodiments, component mounting structure 230 may be configured to include, attach, house, and / or mount satellite modem 290, so that satellite modem 290 may be housed within the central chamber of housing 220. Componentmounting structure 230 may house the satellite modem 290 in an uppermost compartment of component mounting structure 230. In some other embodiments, component mounting structure 230 may be configured to mount satellite modem 290 on a top exterior surface of component mounting structure 230.

[0137] Data acquisition unit also includes a vibration transducer 260 configured to receive vibrations via the vibrations sensing portion 227 and generate an output signal based on the received vibrations. For example, the output signal generated from the vibration transducer is an analogue output signal. According to some embodiments, the lower part 226 includes the vibration transducer 260. Vibration transducer 260 may be cable connected to either PCBA 250 or PCBA 255. This cabling may allow communicative coupling to processor 1484 and / or analogue to digital converter (ADC) 1420. The cabling may be insulated to reduce the internal noise of the data acquisition unit 110. In some embodiments, the cabling is between about 10 to 30 cm in length. In some embodiments, another cabling is between about 15 to 20 cm in length. The short length of cabling and / or insulated cabling may reduce the internal noise of the data acquisition unit 110 and improve quality of measurements. According to some embodiments, a lower portion / side / face of component mounting structure 230 includes a recess for allowing cabling to / from vibration transducer 260 to other components of data acquisition unit 110, such as first PCBA 250 and / or second PCBA 255. The recess for allowing cabling to / from vibration transducer 260 may also allow a portion of vibration transducer 260 to be located in component mounting structure 230 and / or within the recess.

[0138] Vibration transducer 260 may be or include a single geophone. Vibration transducer 260 may be arranged to act as a vertical axis geophone element. The geophone may measure vibrations between about 0.1 to 7 Hz. The geophone may have a natural frequency between about 1 to 10 Hz. The geophone may have a natural frequency between about 1 to 3 Hz, 1 to 5 Hz, or 2 to 8 Hz, for example. The geophone may have a natural frequency of about 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, or 10 Hz, for example. In particular, the geophone may be selected to have anatural frequency of about 2 Hz. The geophone may have a natural frequency less than 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, or 10 Hz, for example.

[0139] The geophone may have a sensitivity of about 100 to 300 or 100 to 750 V / m / s, for example. Sensitivity of the geophone may be the intrinsic open circuit voltage sensitivity. In various embodiments, the geophone may have a sensitivity of about 180 to 260 V / m / s, 200 to 280 V / m / s, or 240 to 300 V / m / s, for example. In various embodiments, the geophone may have a sensitivity of about 300 to 400 V / m / s, 400 to 500 V / m / s, or 500 to 650 V / m / s, for example. In various embodiments, the geophone may have a sensitivity of about 120, 140, 160, 180, 200, 220, 240, 260, 280, or 300 V / m / s, for example. In various embodiments, the geophone may have a sensitivity of about 320, 350, 400, 450, 500, 550, 600, 650, 700, or 750 V / m / s, for example. In various embodiments, the geophone may have a sensitivity greater than 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 350, 400, 450, 500, 550, 600, 650, 700, or 750 V / m / s, for example. For example, the geophone may have a sensitivity greater than 250 V / m / s and a natural frequency less than 2.25 Hz. In another example, the geophone may have a sensitivity greater than 200 V / m / s and a natural frequency less than 3 Hz. In another example, the geophone may have a sensitivity of about 260 V / m / s and a natural frequency of about 2 Hz. In another example, the geophone may have a sensitivity greater than 550 V / m / s and a natural frequency less than 1.25 Hz. In another example, the geophone may have a sensitivity of about 650 V / m / s and a natural frequency of about 1 Hz. The geophone may be a high- sensitivity geophone, such as a ST-2A geophone available from Seis Tech, for example.

[0140] Data acquisition unit 110 can acquire seismic data for ambient noise tomography without the use of active seismic sources and / or stimulated responses. Vibration transducer 260 may be suitable for acquiring low frequency vibrations under 5 Hz. This combination of high sensitivity and low natural frequency allows the vibration sensing module 260 to detect vibrations of a lower frequency than an element of 10 or even 5 Hz. More specifically, the vibration transducer 260 has a higher response gain in the low frequency range of 0.05 to 3 Hz. More traditional nodes with a lower sensitivity and natural frequency at 5 or 10 Hz are more suitable for activeseismic methods. The geophone may be configured for measuring Rayleigh waves. In some embodiments, vibration transducer 260 may comprise three geophones measuring three perpendicular axes. Accordingly, the geophone may be a single tri-axial geophone unit, where such a unit is available. The three geophones or tri-axial geophone unit may be configured for measuring Love waves, for example. Each of the geophones / tri-axial geophone unit may have the same and / or similar sensitivity and natural frequency parameters as described above.

[0141] Data acquisition unit 110 may include a light emitting diode (LED) indicator 272. LED indicator 272 may illuminate, dim, and / or turn off to indicate at least one of: boot-up sequence, connection to peripherals, the modem 290 detecting a satellite 130, an alignment of the data acquisition unit 110 is within a suitable threshold for operational orientation based on data from the accelerometer, or warnings concerning battery level, for example. LED indicator 272 may illuminate different colors such as green, amber, or red, for example.

[0142] Data acquisition unit 110 may include a level indicator 270. Level indicator 270 may be a spirit or bubble level indicator. Level indicator 270 may be a bulls-eye indicator. Level indicator 270 may assist an operator with orienting the data acquisition unit 110 when deploying or physically manipulating the device, particularly for the alignment of vibration transducer 260 with a local gravity vector. Level indicator 270 may be on the top surface of upper part 223, or another surface of data acquisition unit 110 that may be visible when the data acquisition unit 110 is embedded in the ground, for example.

[0143] Data acquisition unit 110 may include a charge port 274. Upper part 223 may include the charge port 274. Charge port 274 may be referred to as charging port 274. Charge port 274 may be connected or connectable to power source 240. External power sources may connect to charge port 274 in order to charge power source 240. In some other embodiments, data acquisition unit 110 may include a user input 274, such as a push button 274. User input 274 may be a touch sensor, button, or switch mechanismelectrically connected to PCBAs 250 and / or 255 to power cycle the electronic components of the data acquisition unit 110, such as processor 1484.

[0144] Data acquisition unit 110 may include a debugging port 276. Upper part 223 may include the debugging port 276. Debugging port 276 may be a serial communications port 276. Debugging port 276 may be communicatively coupled to one or more components on first PCBA 250 and / or second PCBA 255. Debugging port 276 may be used to allow an operator to connect an external computing device to data acquisition unit 110 to extract data, perform firmware updates, and / or perform remote debugging, for example.

[0145] Data acquisition unit 110 may include a charge port 278. Upper part 223 may include the charge port 278. Charge port 278 may be a 2 mm power socket, for example. Charge port 278 may be connected or connectable to at least one of: one or more components on first PCBA 250, one or more components on second PCBA 255, or power source 240. External power sources may connect to charge port 278 in order to charge at least one of: one or more components on first PCBA 250, one or more components on second PCBA 255, or power source 240.

[0146] Figure 3 shows an external perspective view of data acquisition unit 110 according to some embodiments. More specifically, Figure 3 shows an external perspective view of housing 220 and satellite modem 290 of data acquisition unit 110 when assembled, according to some embodiments.

[0147] As shown in Figure 3, the shape of the housing 220 (excluding protruding flange 225 and 228, and / or vibration sensing portion 227) may be substantially prism shaped, cylindrical, and / or hexagonal prism shaped. Power part 226 may include a substantially prism, cylindrical, and / or hexagonal prism shaped upper portion. Lower part 226 may include a dome shaped lowermost portion. The dome shaped lowermost portion of lower part 226 may be flattened in the centre. The flattened centre of the dome shaped lowermost portion of lower part 226 may include the vibration sensing portion 227.

[0148] In some embodiments, as shown in Figure 3, the lower part flange 228 may include a plurality of fastener portions 329 for receiving respective plurality of fasteners 330 to secure the upper part 223 to the lower part 226. The lower part flange 228 may accordingly include respective recess within each the fastener portion 329 for receiving a respective fastener 330. The upper part flange 225 may accordingly include respective recesses for receiving the respective fastener 330. Each fastener receiving portion 329 may be a tubular shape protrusion from a lower side of the lower part flange 228.

[0149] As shown in Figure 3, vibration sensing portion 227 may include one or more radial buttresses extending to the underside of the lower part 226. The one or more radial buttresses may assist securing data acquisition unit 110 in the earth for resisting and / or mitigating rotation of data acquisition unit 110. Vibration sensing portion 227 may include a frustoconically shaped portion. Vibration sensing portion 227 may include a cone shaped portion. The vibration sensing portion 227 may extend from the lower part 226 generally tapering inwards to form a frustoconical shaped portion, and then further tapering more gradually inwards to form a distal tip and cone shape portion.

[0150] As shown in Figure 3, the satellite modem 290 may be attached to upper part 223 of data acquisition unit 110. Also, as shown in Figure 3, level indicator 270 and FED indicator 272 may be included on the top surface of upper part 223 of data acquisition unit 110. Furthermore, Figure 3 shows debugging port 276 and charge port 278 included on upper part 223 of data acquisition unit 110.

[0151] Figure 3 also shows a longitudinal axis 305, here described as a vertical axis 305, through data acquisition unit 110. The vertical axis 305 is not a component of data acquisition unit 110, rather it is shown as a marker and frame of reference in the drawings. The vertical axis 305 is shown in Figure 3 to extend along a centre line from the top of data acquisition unit 110 through the distal tip of the vibration sensing portion 227. The distal tip is generally aligned with a longitudinal centre line through the centre of the housing from the upper part through the lower part. In someembodiments, when data acquisition unit 110 is in an operational orientation, the vertical axis 305 may be parallel, substantially parallel, or somewhat parallel to a gravity field vector.

[0152] Figure 4 shows a perspective view of the modem 290, electronics, and upper part 223 of data acquisition unit 110 during assembly, according to some embodiments. Figure 4 shows a first sub-assembly 403. In some embodiments, the first sub-assembly 403 may include upper part 223, component mounting structure 230 receiving power source 240 and bearing first PCBA 250 and second PCBA 255, and modem 290. First sub-assembly 403 may be referred to as upper sub-assembly 403 or modem integration sub-assembly 403.

[0153] As shown in Figure 4, the component mounting structure 230 is receiving the power source 240. Also shown in Figure 4, the component mounting structure 230 is mounting the first PCBA 250 and second PCBA 255. In some embodiments, as shown in Figure 4, the power source 240 includes one or more strips 430. As shown in Figure 4, power source 240 may include two strips 430. Strip 430 may be used for mechanical insulation to the power source 240. Strip 430 may be tape 430. Tape 430 may be foam tape 430. The charge port 274 is also shown in Figure 4. In some other embodiments, an underside of a lower portion of component mounting structure 230 may include one or more strips or tapes 430.

[0154] As shown in Figure 4, during assembly, the satellite modem 290 while attached to the upper part 223 which in turn having the component mounting structure 230 bearing electronics attached, may together be oriented upside down or substantially upside down to operational orientation for connecting cabling between electronics, PCBAs, and / or satellite modem 290. This way the satellite modem 290 and electronic cabling can be quickly configured by an operator / assembler.

[0155] In some embodiments, the satellite modem 290 while attached to the upper part 223, may together be oriented upside down or substantially upside down tooperational orientation for locating and attaching the component mounting structure 230 bearing electronics.

[0156] In some embodiments, the satellite modem 290 may be attached to the upper part 223 when oriented upside down or substantially upside down to operational orientation. In some other embodiments, the satellite modem 290 may be attached to the upper part 223 when oriented in operational orientation and / or on its side.

[0157] Figure 5 shows an exploded view of the modem 290, component mounting structure 230, electronics and upper part 223 of data acquisition unit 110 according to some embodiments. In particular, Figure 5 shows an exploded view of first subassembly 403. Figure 6A shows a perspective view of the component mounting structure 230 receiving power source 240, and mounting first PCBA 250, second PCBA 255, antenna 580, and modem port 535 according to some embodiments.

[0158] The component mounting structure 230 may comprise one or more pieces. The component mounting structure 230 may comprise multiple pieces. The component mounting structure 230 may include a component mounting structure foundation part 532 and optionally a first separation part 538 and / or a second separation part 539.

[0159] The component mounting structure 230 may include the component mounting structure foundation part 532. The component mounting structure foundation part 532 may comprise three concatenated sides or faces, shaped as a u-shape. In some other embodiments, the component mounting structure foundation part 532 may comprise four concatenated sides or faces, shaped as a rectangular hollow section.

[0160] The component mounting structure 230 may include a first PCBA recess 536 on the panel which mounts the first PCBA 250. The first PCBA recess 536 may allow cables to / from the first PCBA 250 from / to other components of data acquisition unit 110, such as second PCBA 255 and / or satellite modem 290, for example. The component mounting structure foundation part 532 may include the first PCBA recess 536. The component mounting structure 230 may include a second PCBA recess 537on the panel which mounts the second PCBA 255. The second PCBA recess 537 may allow cables to / from the second PCBA 255 from / to other components of data acquisition unit 110, such as first PCBA 250 and / or satellite modem 290, for example. The component mounting structure foundation part 532 may include the second PCBA recess 537.

[0161] The component mounting structure 230 may include a modem recess 534. The component mounting structure foundation part 532 may include the modem recess 534. Modem recess 534 may allow cabling for data communications and / or power to / from the satellite modem 290 from / to first PCBA 250, second PCBA 255, and / or satellite modem 290, for example.

[0162] The component mounting structure 230 may include the first separation part 538. The first separation part 538 may be attached to one or more lower-most portions of the component mounting structure foundation part 532. When attached and in operational orientation, the first separation part 538 may mount the power source 240, as shown in Figure 6A.

[0163] The component mounting structure 230 may include the second separation part 539. The second separation part 539 may be attached to proximate and parallel to the uppermost portion of the component mounting structure foundation part 532. When attached and in operational orientation, the second separation part 539 may be located below the uppermost portion of the component mounting structure foundation part 532, as shown in Figure 6A. When attached and in operational orientation, the second separation part 539 may secure, hold, and / or clamp the power source 240 to the first separation part 538, as shown in Figure 6 A.

[0164] Component mounting structure 230 may also include antenna mount 533 for mounting antenna 580. Antenna mount 533 may be proximate to the uppermost portion of the component mounting structure foundation part 532. The antenna mount 533 may be configured to attach the antenna 580 proximate and parallel to the uppermost portion of the component mounting structure foundation part 532, as shown in Figure 6A. Theantenna mount 533 may be configured to attach the antenna 580 below the uppermost portion of the component mounting structure foundation part 532 and within the component mounting structure 230, as shown in Figure 6A. Therefore, antenna 580 may be contained within the central chamber of housing 220. Antenna 580 may be contained within the component mounting structure 230. Antenna 580 may be contained within the upper volume enclosed by component mounting structure 230. The antenna 580, when mounted via the antenna mount 533, may be mounted horizontally. Antenna 580 may be mounted via antenna mount 533 so that the antenna 580 is substantially perpendicular to the longitudinal axis 305.

[0165] The data acquisition unit 110 also includes the antenna 580. The antenna 580 is configured to receive a synchronisation signal from a satellite. The antenna 580 may be configured to receive a GNSS signal from the satellite. Antenna 580 may be referred to as synchronisation antenna 530 or GNSS antenna 580. In some embodiments, antenna 580 is an active antenna. In some other embodiments, antenna 580 is a passive antenna. Antenna 580 may be a monopole antenna, such as a Taoglas monopole antenna. The monopole antenna may have relatively easy assembly. The monopole antenna may have a relatively reliable and secure physical connection / connector. The monopole antenna and its antenna mount 533 may have a relatively compact formfactor. In some other embodiments, antenna 580 is a flexible printed circuit (FPC) antenna, such as the Taoglas Flexible Printed Circuit (FPC) antenna. The FPC antenna may be tuneable to better operate in an enclosed space. In some other embodiments, antenna 580 is a patch antenna, such as a Molex / Linx patch antenna. The patch antenna may have a high gain.

[0166] The data acquisition unit 110 may also include a modem port 535. Modem port 535 may be attached to component mounting structure 230. The modem port 535 may be attached proximate and parallel to the uppermost portion of the component mounting structure foundation part 532, as shown in Figure 6A. The modem port 535 may be attached below the uppermost portion of the component mounting structure foundation part 532 and within the component mounting structure 230, as shown in Figure 6 A. Therefore, modem port 535 may be contained within the central chamber ofhousing 220. Modem port 535 may be contained within the component mounting structure 230. Modem port 535 may be contained within the upper volume enclosed by component mounting structure 230. Data communication and / or power supply cabling may be fed from satellite modem 290 to modem port 535. Data communication and / or power supply cabling may be fed from satellite modem 290 through modem recess 534 of component mounting structure 239 to modem port 535. Data communication and / or power supply cabling may be fed from satellite modem 290 through cable recess / port 229 and modem recess 534 of component mounting structure 239 to modem port 535. Data communication and / or power supply cabling may be fed from modem port 535 to first PCBA 250, second PCBA 255 and / or power source 240.

[0167] Component mounting structure 230 may include a first compartment. The first compartment may include the antenna 580, antenna mount 533, and / or modem port 535. Component mounting structure may include a second compartment. The second compartment may include the power source 240. When attached together, the component mounting structure foundation part 532 and second separation part 539 may form a first compartment for housing the antenna 580, antenna mount 533, and / or modem port 535. When attached together, the component mounting structure foundation part 532, second separation part 539 and the first separation part 538 may form a second compartment for mounting power source 240.

[0168] Figure 5 may be a visual reference for detailing assembly of data acquisition unit according to some embodiments. As shown in Figure 5, the satellite modem 290 may be attached to the upper part 223 when oriented upside down or substantially upside down to operational orientation by fasteners 590. The upper part 223 may be advantageously positioned upside down when attaching the component mounting structure 230, when mounting electronics to the component mounting structure 230, when wiring the electronics and the modem 290, and / or when attaching the lower part 226 to the upper part 223 to house the component mounting structure 230.

[0169] Charge port 274, debug port 276, and charge port 278 may be attached to upper part 223 after satellite modem 290 has been attached to upper part 223 and / orsatellite modem 290 and upper part 223 are oriented upside down to operational orientation.

[0170] Level indicator 270 and LED indicator 272 may be attached to upper part 223 before or after satellite modem 290 has been attached to upper part 223 and / or satellite modem 290 and upper part 223 are oriented upside down to operational orientation.

[0171] After the satellite modem 290 has been attached to the upper part 223 and together oriented upside down, the component mounting structure 230 may then be attached to the inside of upper part 223. Component mounting structure 230 may be attached to the inside of upper part 223 via fasteners. Before component mounting structure 230 is attached to upper part 223, the antenna mount 533 and / or antenna 580 may be attached to component mounting structure 230. Before component mounting structure 230 is attached to upper part 223, the modem port 535 may be attached to component mounting structure 230. Before component mounting structure 230 is attached to upper part 223, the power source 240 may be received in the component mounting structure 230. Before component mounting structure 230 is attached to upper part 223, one or more of first separation part 538, second separation part 539, first PCBA 250, and / or second PCBA 255 may be attached to component mounting structure 230. After component mounting structure 230 is attached to upper part 223 and the component mounting structure 230, upper part 223, and satellite modem 290 are upside down to an operational orientation, an operator / assembler may cable electronic components, power source 240, first PCBA 250, second PCBA 255, satellite modem 290, antenna 580, modem port 535, charge port 274, debug port 276, charge port 278, and / or LED indicators 272 to each other and / or other components of data acquisition unit 110.

[0172] Figure 6B shows, within a semi-transparent view of upper part 223 of data acquisition unit 110, a perspective view of the component mounting structure 230 of data acquisition unit 110 bearing electronics while attached to upper part 223 according to some other embodiments.

[0173] According to some other embodiments the component mounting structure 230 comprises a mounting body including three concatenated panels, sides or faces, shaped as a u-shape, as shown in Figure 6B. According to some other embodiments, component mounting structure 230 consists of a foundation part 532 forming the mounting body. Component mounting structure 230 may include two opposing panels. Component mounting structure may include outer side faces on each of the two opposing panels, one side face bearing first PCBA 250 and the other side face bearing second PCBA 255 as shown in Figure 6B. The two outer side faces may be located on opposed sides of the component mounting structure 230. The two opposing panels may include inner side faces that the power source 240 may be located within, as shown in Figure 6B. The power source 240 may be further supported within the component mounting structure 230 by being mounted upon a component retention plate or flange, such as component mounting platform 830, as shown in Figures 9 and 12.

[0174] According to some other embodiments, component mounting structure 230 does not mount antenna 580. According to some other embodiments, component mounting structure 230 does not include and / or attach antenna mount 533. According to some other embodiments, an inner surface of upper part 223 may include one or more antenna mounts 533. According to some other embodiments, antenna 580 may be mounted to the one or more antenna mounts 533 on upper part 223. Each antenna mount 533 may comprise a ring. Each antenna mount 533 may suspend the antenna 580. Each antenna mount 533 may hold the antenna 580. Each antenna mount 533 may comprise a ring to hold and suspend antenna 580. According to some other embodiments, an inner surface of upper part 223 includes two antenna mounts 533, as shown in Figure 6B. Antenna 580 may be a monopole antenna, as shown in Figure 6B. One or more antenna mounts 533 and antenna 580 may be located proximate to mounts for level indicator 270, which may be referred to as level indicator mounts 670. One or more antenna mounts 533 and antenna 580 may be located proximate to an edge of the top portion of the upper part 223. Antenna 580 may be mounted parallel with the top portion of the upper part 223 by one or more antenna mounts 533.

[0175] According to some other embodiments, upper part 223 includes a plurality of fastening portions 630. As shown in Figure 6B, upper part may include four fastening portions 630. Each fastening portion 630 may be a protrusion. Each fastening portion 630 may include a recess for receiving one or more fasteners. Each fastening portion 630 may be used for securing component mounting structure 230 to upper part 223. Accordingly, component mounting structure 230 may have corresponding plurality of recesses for also receiving the one or more fasteners.

[0176] Charge port 274 and upper part flange 225 are also shown in Figure 6B for reference.

[0177] Figure 7 shows a perspective view of the underside of satellite modem 290 according to some embodiments.

[0178] The underside of the housing of satellite modem 290 may include a satellite modem communication port 771 for connecting one or more cables for data communications and / or power to / from the satellite modem 290 from / to cable recess / port 229, modem recess 534, modem port 535, first PCBA 250, second PCBA 255, and / or power source 240, for example.

[0179] Figure 8 shows an exploded view of the vibration transducer 260, a component mounting structure platform 830, and lower part 226 of data acquisition unit 110 according to some embodiments. Figure 8 shows a second sub-assembly 806. In some embodiments, the second sub-assembly 806 may include lower part 226 including a vibration sensing projection 227, component mounting structure platform 830, and vibration transducer 260. Second sub-assembly may include washer 836. Second sub-assembly 806 may be referred to as lower sub-assembly 806 or seismic sensor integration sub-assembly 806.

[0180] According to some other embodiments, data acquisition unit 110 includes a component mounting structure platform 830. Component mounting structure platform 830 may mount the component mounting structure 230 and / or power source 240.Component mounting structure platform 830 may be particularly useful with the embodiments of the component mounting structure 230 and power source 240 of Figure 6B. In some embodiments, the power source 240 may be retained on an upper surface and optionally one or more side surfaces by component mounting structure 230. In some embodiments, power source 240 may be supported on a lower surface by component mounting structure platform 830. In some embodiments, component mounting structure 230 may be supported by component mounting structure platform 830.

[0181] Component mounting structure platform 830 may be a thin sheet or plane. Component mounting structure platform 830 may be referred to as top plate 830 or component mounting platform 830. Component mounting structure platform 830 may be rectangular. Component mounting structure platform 830 may be 0.5 mm to 5 mm thick. Component mounting structure platform 830 may be aluminium or plastic material. Component mounting structure platform 830 may comprise Acrylonitrile butadiene styrene (ABS). Component mounting structure platform 830 may comprise polycarbonate (PC). Component mounting structure platform 830 may comprise a blend of PC and ABS.

[0182] Component mounting structure platform 830 may include a platform cable recess 832. Platform cable recess 832 may allow cabling for communications from / to vibration transducer 260 through component mounting structure platform 830 to / from first PCBA 250 and / or second PCBA 255. Platform cable recess 832 may be centrally located on component mounting structure platform 830 and may extend as a narrow channel to the edge of the component mounting structure platform 830, so that cabling can be fed within the channel underneath the power source 240 and / or component mounting structure 230.

[0183] Component mounting structure platform 830 may also include a plurality of recesses for attaching component mounting structure platform 830 to lower part 226 via fasteners. When attached, component mounting structure platform 830 may contact or be proximate to vibration transducer 260. There may be grease or another lubricantapplied to at least one outer surface of the vibration transducer 260, such as a top surface.

[0184] Data acquisition unit 110 may include a sealing washer 836 which may be used to cushion between the component mounting structure platform 830 and vibration transducer 260. Sealing washer 836 may provide tolerance for variabilities in the gap between the vibration transducer 260 and component mounting structure platform 830. Sealing washer 836 may provide tolerance for variabilities in the amount of grease or other lubricant applied to the at least one outer surface of the vibration transducer 260.

[0185] Figure 9 shows a cross-sectional view of the vibration transducer 260, component mounting structure platform 830, and lower part 226 of data acquisition unit 110 according to some embodiments.

[0186] Figure 9 shows the vibration transducer 260, sealing washer 836, component mounting structure platform 830, and lower part 226 assembled together according to some embodiments.

[0187] Lower part 226 may include a transducer holding structure 926. Transducer holding structure 926 may protrude from lower part 226 into the central chamber of housing 220. Transducer holding structure 926 may be located around the centre of the central chamber facing floor of lower part 226. Transducer holding structure 926 may include a recess to receive vibration transducer 260. Transducer holding structure 926 may receive vibration transducer 260 so that most of the length of vibration transducer 260 is contained in the recess. The recess of transducer holding structure 926 may be sized so that the inner wall of transducer holding structure 926 may be in contact with the outer wall of vibration transducer 260 to hold the vibration transducer 260.Transducer holding structure 926 may be cylindrically shaped. Transducer holding structure 926 may be integrally formed with lower part 226. In some other embodiments, transducer holding structure 926 may be attached to lower part 226.

[0188] At least one of: the inner walls of the vibration holding structure 926 or the outer walls of the vibration transducer 260 may be greased.

[0189] Vibration sensing portion 227 may include a hollow channel or recess 927 extending from the centre of the inner recessed floor of lower part 226 (that receives the geophone / vibration transducer 260) to a location proximate to the distal tip of the vibration sensing portion 227. Hence, vibration sensing portion 227 may include a surface or wall surrounding and / or defining recess 927. Channel or recess 927 may ensure that portions of the vibration sensing portion 227 do not exceed a maximum thickness. Channel or recess 927 may aid in homogeneous cooling of vibration sensing portion 227 when vibration sensing portion 227 is formed in a moulding process, such as injection moulding.

[0190] As can be seen in Figure 9, component mounting structure platform 830 may have a greater cross-sectional area than transducer holding structure 926.

[0191] Lower part flange 228 and platform cable recess 832 are also shown in Figure 9 for reference.

[0192] Figure 10 shows a cross-sectional view of the lower part 226 of data acquisition unit according to some embodiments.

[0193] As shown in Figure 10, transducer holding structure 926 may include a plurality of fastener portions 1027. Each of the plurality of fastener portions 1027 may include a recess for receiving a fastener. In use, component mounting structure platform 830 may be placed over the transducer holding structure 926, and fasteners may be located through the recesses in the component mounting structure platform 830 and the fastener portions 1027. Each of the plurality of fastener portions 1027 may extend the length of transducer holding structure 926 from the central chamber facing floor of the lower part 226 to the rim of the transducer holding structure 926. Each of the plurality of fastener portions 1027 may be cylindrically shaped. Each of the plurality of fastener portions 1027 may protrude from or connect to transducer holdingstructure 926. Each of the plurality of fastener portions 1027 may be equally spaced from each other around the circumference of the transducer holding structure 926. There may be four fastener portions 1027. The transducer holding structure 926 is configured to transfer vibrations impinging on (received by) the housing, particularly the lower part 226 and the vibration sensing portion 227, to the vibration transducer 260.

[0194] Figure 10 also shows vibration sensing portion 227, recess 927, and lower part flange 228.

[0195] Figure 11 shows an exploded view of data acquisition unit 110 according to some embodiments.

[0196] As shown in Figure 11, upper part 223 and lower part 226 may attach together to form housing 220. Upper part 223 and lower part 226 may attach together upside down and / or an inverted orientation to the operational orientation. Upper part 223 and lower part 226 may attach together to form housing 220 using an o-ring 1125 at the rim / flanges for ingress protection against liquid, dust, dirt, etc. Accordingly housing 220 may only have a single point of ingress. Housing 220 may have an ingress protection rating of IP68.

[0197] Prior to the attachment of upper part 223 and lower part 226 together, satellite modem 290, and component mounting structure 230 may be attached to upper part 223, as shown in Figure 11. Prior to the attachment of upper part 223 and lower part 226 together. Though not shown in Figure 11, prior to the attachment of upper part 223 and lower part 226 together, the vibration transducer 260, sealing washer 836, component mounting structure platform 830, and lower part 226 may be assembled together, as shown in Figure 9. Strip or tape 430 is also shown in Figure 11. Tape 430 may contact component mounting structure platform 830 when the data acquisition unit 110 is assembled.

[0198] Figure 12 shows a cross-sectional view of data acquisition unit 110 according to some embodiments.

[0199] As shown in Figure 12, the lower part 226 (excluding the vibration sensing portion 227) may be about double the length (height) of the upper part 223 (excluding satellite modem 290).

[0200] As shown in Figure 12, the vibration sensing portion 227 may be about the same length (height) as the upper part 223 (excluding satellite modem 290).

[0201] In some embodiments, the walls / faces of component mounting structure 230 or 2230 (shown and described in relation to Figure 20) may have a thickness between about 1 mm to 10 mm. Component mounting structure 230 or 2230 may be aluminium or plastic material. Component mounting structure 230 or 2230 may comprise Acrylonitrile butadiene styrene (ABS). Component mounting structure 230 or 2230 may comprise polycarbonate (PC). Component mounting structure 230 or 2230 may comprise a blend of PC and ABS. Component mounting structure 230 or 2230 may be formed from injection moulding.

[0202] The width (diameter) of upper part 223 including upper part flange 225 may be between about 140 to 250 mm. According to some embodiments, the width (diameter) of upper part 223 including upper part flange 225 is between about 150 to 185 mm, 180 to 200 mm, or 190 to 230 mm. In some embodiments, the width (diameter) of upper part 223 including upper part flange 225 is about 180, 182, 184, 186, 188, 190, 192, or 194 mm. In some embodiments, the width (diameter) of upper part 223 including upper part flange 225 is about 184 mm.

[0203] The width (diameter) of lower part 226 including lower part flange 228 may be between about 140 to 250 mm. According to some embodiments, the width (diameter) of lower part 226 including lower part flange 228 is between about 150 to 185 mm, 180 to 200 mm, or 190 to 230 mm. In some embodiments, the width (diameter) of lower part 226 including lower part flange 228 is about 180, 182, 184,186, 188, 190, 192, or 194 mm. In some embodiments, the width (diameter) of lower part 226 including lower part flange 228 is about 184 mm.

[0204] According to some embodiments, lower part flange 228 may extend between about 2 to 40 mm from housing 220. According to some embodiments, upper part flange 225 may extend between about 2 to 40 mm from housing 220. According to some embodiments, lower part flange 228 may extend between about 2 to 10 mm, 5 to 20 mm, or 10 to 30mm from housing 220. According to some embodiments, upper part flange 225 may extend between about 2 to 10 mm, 5 to 20 mm, or 10 to 30mm from housing 220.

[0205] The length (height) of data acquisition unit 110 including satellite modem 290 and vibration sensing portion 227 may be between about 200 to 300 mm. According to some embodiments, the length (height) of data acquisition unit 110 including satellite modem 290 and vibration sensing portion 227 is between about 200 to 250 mm, 250 to 270 mm, or 260 to 280 mm. In some embodiments, the length (height) of data acquisition unit 110 including satellite modem 290 and vibration sensing portion 227 is about 245, 250, 255, 260, 265, or 270 mm. In some embodiments, the length (height) of data acquisition unit 110 including satellite modem 290 and vibration sensing portion 227 is about 265 mm.

[0206] In some embodiments, the walls of upper part 223 and lower part 226 may have a uniform thickness where possible and have smooth transitions of thickness. In some embodiments, the walls of upper part 223 and lower part 226 may have a thickness between about 3 to 10 mm.

[0207] Upper part 223 or 2223 (shown and described in relation to Figure 20) may be formed of or comprise plastic material. Upper part 223 or 2223 may comprise Acrylonitrile butadiene styrene (ABS). Upper part 223 or 2223 may comprise polycarbonate (PC). Upper part 223 or 2223 may comprise a blend of PC and ABS. Upper part 223 or 2223 may be formed from injection moulding. Upper part 223 or2223 may be plastic material rather than metallic so that upper part 223 or 2223 does not block signals to at least one of: antenna 580 or modem 290.

[0208] Lower part 226 or 2226 (shown and described in relation to Figure 20) may be aluminium or plastic material. Lower part 226 or 2226 may comprise Acrylonitrile butadiene styrene (ABS). Lower part 226 or 2226 may comprise polycarbonate (PC). Lower part 226 or 2226 may comprise a blend of PC and ABS. Lower part 226 or 2226 may be formed from injection moulding.

[0209] Vibration sensing portion 227 may be aluminium or plastic material. Vibration sensing portion 227 may comprise Acrylonitrile butadiene styrene (ABS). Vibration sensing portion 227 may comprise polycarbonate (PC). Vibration sensing portion 227 may comprise a blend of PC and ABS. Vibration sensing portion 227 may be formed from injection moulding.

[0210] As shown in Figure 12, power source 240 may comprise at least 40% of the cross-sectional area of the central chamber inside of the housing 220, when viewed from the side. In some embodiments, power source 240 may comprise at least 35%, 40%, 45%, 50%, 55%, 60%, or 65% of the cross-sectional area of the inside of the housing 220, when viewed from the side. In some embodiments, power source 240 may comprise at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% of the interior volume of housing 220. In some embodiments, housing 220 and / or housing interior walls define an interior space shaped as a prism. In some embodiments, the housing 220 and / or housing interior walls are cylindrically shaped.

[0211] The width of power source 240 or 2240 may be between about 40 to 100 mm. According to some embodiments, the width of power source 240 or 2240 is between about 50 to 75 mm, 60 to 80 mm, or 70 to 90 mm. In some embodiments, the width of power source 240 or 2240 is about 62, 65, 68, 70, 72, 74, 76, 78, 79, 81, 84, or 87 mm. In some embodiments, the width of power source 240 or 2240 is about 76 mm. In some embodiments, the width of power source 240 or 2240 is about 79 mm.

[0212] The height of power source 240 or 2240 may be between about 40 to 100 mm. According to some embodiments, the height of power source 240 or 2240 is between about 50 to 75 mm, 60 to 80 mm, or 70 to 90 mm. In some embodiments, the height of power source 240 or 2240 is about 62, 65, 68, 70, 72, 74, 76, 78, 81, 84, or 87 mm. In some embodiments, the height of power source 240 or 2240 is about 72 mm. In some embodiments, the height of power source 240 or 2240 is about 74 mm.

[0213] The length of power source 240 or 2240 may be between about 40 to 130 mm. According to some embodiments, the length of power source 240 or 2240 is between about 50 to 75 mm, 70 to 115 mm, or 90 to 120 mm. In some embodiments, the height of power source 240 or 2240 is about 100, 104, 108, 112, 114, 116, 117, 118, 122, 126, or 130 mm. In some embodiments, the length of power source 240 or 2240 is about 114 mm. In some embodiments, the length of power source 240 or 2240 is about 117 mm.

[0214] In some embodiments, the component mounting structure 230 may have a similar height and a similar length or width as power source 240. In some embodiments, the component mounting structure may have substantially less width or length than power source 240. The use of component mounting structure 230 to contain power source 240 and electronics helps realise an internal volume efficiency within the data acquisition unit 110.

[0215] The width of component mounting structure 230 or 2230 may be between about 40 to 100 mm. According to some embodiments, the width of component mounting structure 230 or 2230 is between about 40 to 75 mm, 60 to 80 mm, or 70 to 90 mm. In some embodiments, the width of component mounting structure 230 or 2230 is about 62, 65, 68, 70, 72, 74, 76, 78, 81, 84, 87, 89, 92, 95, 97, or 100 mm. In some embodiments, the width of component mounting structure 230 or 2230 is about 76 mm. In some embodiments, the width of component mounting structure 230 or 2230 is about 89 mm. In some embodiments, the width of component mounting structure 230 or 2230 is about 45 mm.

[0216] The height of component mounting structure 230 or 2230 may be between about 40 to 100 mm. According to some embodiments, the height of component mounting structure 230 or 2230 is between about 50 to 75 mm, 60 to 80 mm, 70 to 90 mm, or 80 to 100 mm. In some embodiments, the height of component mounting structure 230 or 2230 is about 62, 65, 68, 70, 72, 74, 76, 78, 81, 84, 87, 90, 95, 97, or 100 mm. In some embodiments, the height of component mounting structure 230 or 2230 is about 90 mm. In some embodiments, the height of component mounting structure 230 or 2230 is about 97 mm. In some embodiments, the height of component mounting structure 230 or 2230 is about 60 mm.

[0217] The length of component mounting structure 230 or 2230 may be between about 40 to 130 mm. According to some embodiments, the length of component mounting structure 230 or 2230 is between about 50 to 75 mm, 70 to 115 mm, or 110 to 150 mm. In some embodiments, the height of component mounting structure 230 or 2230 is about 100, 104, 108, 112, 114, 116, 118, 122, 123, 126, or 130 mm. In some embodiments, the length of component mounting structure 230 or 2230 is about 114 mm. In some embodiments, the length of component mounting structure 230 or 2230 is about 123 mm. In some embodiments, the length of component mounting structure 230 or 2230 is about 50 mm.

[0218] In some embodiments, the power source 240 or 2240 has a mass of about 500 grams to about 1200 grams. In some embodiments, the power source 240 has a mass of about 500 grams to about 1500 grams. In some embodiments, the power source 240 or 2240 has a mass between about 500 to 800 grams, 750 to 1100 grams, 900 to 1200 grams, or 1000 to 1300 grams. Power source 240 or 2240 may have a mass of about 1074 grams. Power source 240 or 2240 may have a mass of about 1228 grams. Power source 240 or 2240 may comprise 24 cells and have a mass of 1074 grams. Power source 240 or 2240 may have a mass of about 775 grams. Power source 240 or 2240 may comprise 15 cells and have a mass of about 775 grams.

[0219] In some embodiments, the satellite modem 290 has a mass of about 700 to 900 grams.

[0220] The self-contained data acquisition unit 110 or 2110 including ground sensing module, processor, memory, a power source, and an attachable satellite communications module may have a mass between about 2 to 3 kg, 3 to 4 kg, or 4 to 5 kg. In some embodiments, the self-contained data acquisition unit 110 or 2110 has a mass of about 5, 4.5, 4, 3.5, 3, 2.5, or 2 kg. In some embodiments, the self-contained data acquisition unit 110 or 2110 has a mass of about 2.5 kg to about 3.5 kg.

[0221] In some embodiments, the data acquisition unit 110 including the housing 220, the component mounting structure 230, the electronics, the vibration transducer 260, and the power source 240 has a mass of about 1500 grams to about 3000 grams. In some embodiments, the data acquisition unit 110 including the housing 220, the component mounting structure 230, the electronics, the vibration transducer 260, and the power source 240 between about 1800 to 2000 grams, 1850 to 2250 grams, or 2190 grams to 3375 grams. In some embodiments, the data acquisition unit 110 including the housing 220, the component mounting structure 230, the electronics, the vibration transducer 260, and the power source 240 has a mass of about 1900 grams or 2240 grams.

[0222] In some embodiments, the data acquisition unit 110 including the housing 220, the component mounting structure 230, the electronics, the vibration transducer 260, the power source 240, and the satellite modem 290 has a mass between about 1850 grams to 4000 grams. In some embodiments, the data acquisition unit 110 including the housing 220, the component mounting structure 230, the electronics, the vibration transducer 260, the power source 240, and the satellite modem 290 has a mass between about 1900 to 2300 grams, 2190 to 3375 grams, 2250 to 2650 grams, or 2590 grams to 3775 grams. The data acquisition unit 110 may have a mass between about 1800 grams to about 3400 grams. The data acquisition unit 110 may have a mass between about 2190 grams to about 3375 grams. The data acquisition unit 110 may have a mass between about 1900 to 2300 grams, 2250 to 2650 grams, or 2590 grams to 3775 grams. The data acquisition unit 110 may have a mass of about 2300 grams or 2640 grams.

[0223] Figure 13 shows data acquisition unit 110 when deployed in the field according to some embodiments.

[0224] The data acquisition unit 110 may be deployed so that both or either of lower part flange 228 and upper part flange 225 are exposed or submerged under the earth.

[0225] The data acquisition unit 110 may be deployed so that both of lower part flange 228 and upper part flange 225 are within or proximate to the surface of the earth.

[0226] The data acquisition unit 110 may be deployed so that all or most of upper part 223 is exposed.

[0227] The data acquisition unit 110 may be deployed so that all or most of lower part 226 is submerged in the earth.

[0228] Figure 14A shows first printed circuit board assembly 250 of data acquisition unit 110 or 2110 according to some embodiments. Figure 14B shows second printed circuit board assembly 255 of data acquisition unit 110 or 2110 according to some embodiments. The second PCBA 255 may be larger in length (diameter) than the first PCBA 250. In some embodiments, second PCBA 255 is a different shape to first PCBA 250. In some other embodiments, second PCBA 255 is the same shape as first PCBA 25O.In some embodiments, second PCBA 255 and first PCBA 250 comprise the same length (diameter) and / or dimensions.

[0229] Embodiments of the present disclosure may describe an electronic component to be included, carried, borne, and / or mounted as part of a particular printed circuit board assembly. However, data acquisition unit 110 or 2110 may include one or more printed circuit board assemblies. Electronic components described in relation to a particular printed circuit board assembly may additionally or instead be included, carried, borne, and / or mounted on other printed circuit board assemblies of data acquisition unit 110 or 2110.

[0230] First printed circuit board assembly 250 and second printed circuit board assembly 255 may comprise a printed circuit board and bear electronic components of data acquisition unit 110 or 2110. Electronic components of first printed circuit board assembly 250 and second printed circuit board assembly 255 may not initially be attached, but may be attached at a later stage, such as when assembling data acquisition unit 110 or 2110. Therefore, first printed circuit board assembly 250 and second printed circuit board assembly 255 may be configured to attach electronic components.

[0231] The printed circuit board of first printed circuit board assembly 250 may mount inertial measurement unit 1450, analogue to digital converter (ADC) 1420, nonvolatile memory, volatile memory 1440, processor 1484, one or more first PCB connection points 1414, GNSS / synchronisation unit 1494, serial module 1474, and / or power port 1435, as shown in Figure 14A. Power port 1435 may allow connection of external power to power components mounted or connected to first printed circuit board assembly 250.

[0232] The printed circuit board of first printed circuit board assembly may also mount components for connectivity to vibration transducer 260 and / or a programmer / debugger unit.

[0233] Inertial measurement unit 1450 may be a micro-electromechanical system (MEMS) accelerometer. Electronic components may also comprise any other connections or circuit elements, such as diodes, capacitors, inductors, resistors, and transistors.

[0234] In some embodiments, processor 1484 is a microcontroller. Processor 1484 may be a microprocessor. Processor 1484 may be processing circuitry 1484.

[0235] In particular embodiments, processor 1484 includes hardware for executing instructions, such as those making up a computer program. As an example, and not by way of limitation, to execute instructions, processor 1484 may retrieve (or fetch) the instructions from an internal register, an internal cache, volatile memory 1440, or non-volatile memory; decode and execute them; and then write one or more results to an internal register, an internal cache, volatile memory 1440, or non-volatile memory.

[0236] In particular embodiments, processor 1484 may include one or more internal caches for data, instructions, or addresses. This disclosure contemplates processor 1484 including any suitable number of any suitable internal caches, where appropriate. As an example, and not by way of limitation, processor 1484 may include one or more instruction caches, one or more data caches, and one or more translation lookaside buffers (TLBs). Instructions in the instruction caches may be copies of instructions in volatile memory 1440 or non-volatile memory, and the instruction caches may speed up retrieval of those instructions by processor 1484. Data in the data caches may be copies of data in volatile memory 1440 or non-volatile memory for instructions executing at processor 1484 to operate on; the results of previous instructions executed at processor 1484 for access by subsequent instructions executing at processor 1484 or for writing to removable auxiliary memory 1445, non-volatile memory or volatile memory 1440; or other suitable data. The data caches may speed up read or write operations by processor 1484. The TLBs may speed up virtual-address translation for processor 1484.

[0237] In particular embodiments, processor 1484 includes one or more internal registers for data, instructions, or addresses. This disclosure contemplates processor 1484 including any suitable number of any suitable internal registers, where appropriate. Where appropriate, processor 1484 may include one or more arithmetic logic units (ALUs); be a multi-core processor; or include one or more processors 1484. Although this disclosure describes and illustrates a particular processor, this disclosure contemplates any suitable processor.

[0238] Processor 1484 forms part of a processing unit. The processing unit may comprise the printed circuit board of printed circuit board assembly 250. The processing unit may comprise one or more components of the printed circuit board assembly 250. The processing unit or processor 1484 may comprise volatile memory 1440 and non-volatile memory accessible to the microcontroller of processor 1484. The processing unit may include ADC 1420. The processing unit may be configured toreceive and process the output signal of the vibration transducer 260 to generate a data payload. The data payload may include a timestamp followed by an array of bytes representing the pre-processed data. A format of this data payload may be referred to as ambient noise tomography (ANT) format. The satellite modem 290 may be configured to receive one or more generated payloads from the processing unit and / or processor 1484 and transmit the one or more generated payloads to satellite 130. The processing unit may be configured for controlling operation of the data acquisition unit 110, most of the work of which is performed by processor 1484. Processor 1484 may be communicatively coupled to ADC 1420. Processor 1484 may be communicatively coupled to inertial measurement unit 1450. Processor 1484 may be communicatively coupled to satellite modem 290. Processor 1484 is communicatively coupled or couplable via cabled connections in the central chamber from processor 1484 and / or first printed circuit board assembly 250 to satellite modem 290.

[0239] Non-volatile memory may comprise operating system (OS) code. Non-volatile memory may also comprise pre-determined or periodically determined operational parameters and device operation management code. Non-volatile memory may also comprise code to control sampling of the vibration transducer 260. Non-volatile memory further comprises pre-processor code for performing pre-processing functions in relation to ground movement data received via vibration transducer 260 and ADC 1420 as described herein.

[0240] For example, when executed by processor 1484, pre-processor code may cause the processor 1484 to activate vibration transducer 260 and / or ADC 1420 to begin acquiring seismic data samples. The pre-processor code when executed by processor 1484 may cause processor 1484 to downsample and / or decimate the acquired seismic data samples. The pre-processor code when executed by processor 1484 may cause processor 1484 to de-trend or de-bias the (downsampled / decimated) sample seismic data. The pre-processor code when executed by processor 1484 may cause the processor 1484 to convert the time-domain signal of the (downsampled / decimated and / or de-trended) sample seismic data into frequency constituents, such as via a Fast Fourier Transform (FFT) algorithm. The pre-processor code when executed byprocessor 1484 may cause the processor 1484 to apply filtering to the frequency constituents, such as a low pass filter. The pre-processor code when executed by processor 1484 may cause the processor 1484 to spectrally whiten the frequency constituents. The pre-processor code when executed by processor 1484 may cause the processor 1484 to normalize the frequency constituents using a Tukey window function. The pre-processor code when executed by processor 1484 may cause the processor 1484 to convert the (spectrally whitened) frequency constituents to timedomain data, such as via an inverse fast Fourier transform (IFFT) algorithm. The preprocessor code when executed by processor 1484 may cause the processor 1484 to one- bit normalize the time-domain data / sample seismic data. The pre-processor code when executed by processor 1484 may cause the processor 1484 to process the (one-bit normalised) sample seismic data into payloads for scheduled transmission by the satellite modem 290 to a satellite 130.

[0241] The processor 1484 may be configured to send payloads to satellite modem 290 for automatic transmission based on a determined or pre-determined schedule to a satellite 130. Processor 1484 may automatically be configured to send payloads to satellite modem 290 for satellite modem 290 to transmit based on a schedule determined or pre-determined by processor of satellite modem 290. The scheduled transmission may be based on an orbital schedule. The scheduled transmission may be randomised. The scheduled transmission maybe sequenced with the scheduled transmission of other data acquisition units 110. The scheduled transmissions may be based on a constant or average transmission time interval (TTI). TTI may be between about 10 minutes to 4 hours. The TTI may be between 10 to 30 minutes, 10 to 60 minutes, 30 minutes to 2 hours, or 1 hour to 4 hours. The TTI may be about 10, 13, 15, 18, 20, 23, 26, 30, 35, 40, 45, 50, 55, or 60 minutes. The payload sent in the scheduled transmission may be between about 2 kb to 48 kilobytes (kB). The payload sent in the scheduled transmission may be between about 2 to 4 kB, 2 to 10 kB, 4 to 20 kB, or 10 to 40 kB. The payload sent in the scheduled transmission may be about 2, 4, 6, 8, 12, 16, 20, 24, 30, 36, or 48 kB. The duration of a scheduled transmission may be between about 10 seconds to 240 seconds. The duration of a scheduled transmission may be between about 10 to 30 seconds, 10 to 60 seconds, 25 to 150 seconds, or 40 to 200seconds. The duration of a scheduled transmission may be about 10, 15, 20, 25, 30, 40, 50, 60, 120, or 200 seconds.

[0242] Processing unit and / or satellite modem 290 may be configured to transmit about 100 kilobytes to 450 kilobytes of one or more payloads per day to the second satellite. Processing unit and / or satellite modem 290 may be configured to transmit no more than 400 kB per day.

[0243] Satellite modem 290 may consume about 9.6 to 9.8 Wh in a day, based on a transmission duty cycle of about 2% and reception duty cycle of about 12.5%.

[0244] Volatile memory 1440 may comprise buffers and queues for assisting sampling of seismic data and for storing (pre-processed) data payloads before sending / transmitting to satellite modem 290 for scheduled transmission to a satellite 130.

[0245] GNSS unit 1494 may enable processor 1484 to communicate with a GNSS satellite for receiving positioning and timing data. GNSS unit 1494 may be referred to as synchronization unit 1494. Synchronisation unit 1494 may be communicatively coupled with processor 1484 and / or processing unit. Processing unit may include synchronisation unit 1494. Synchronisation unit 1494 may include antenna 580. GNSS unit 1494 may receive a synchronization signal from the GNSS satellite via antenna 580. Synchronisation unit 1494 may communicate synchronization data to processor 1484 and / or processing unit. The GNSS satellite may be a global positioning system (GPS) satellite, for example. GNSS unit 1494 is communicatively coupled to antenna 580 and / or antenna mount 533 via cabled connections.

[0246] Serial module 1474 may enable serial communications between processor 1484, components within data acquisition unit 110, and / or external devices. Serial module 1474 may also be referred to as serial unit 1474. Serial module 1474 may enable RS-232 communications via a serial bus, for example. Serial module 1474 may enable serial communications between processor 1484 and modem 290, for example.

[0247] Power source 240 may supply power to processor 1484 and other components on printed circuit board assemblies 250 and 255. According to some embodiments, power source 240 is also able to supply power to another external device, or other connected device. For example, the other device may be connected and supplied power through a serial connection such as serial connector on data acquisition device 213.

[0248] ADC 1420 may be used to convert voltages measured by components such as vibration transducer 260 and output the digital data to processor 1484. ADC 1420 may be communicatively coupled to processor 1484 and / or vibration transducer 260. In some embodiments, ADC 1420 amplifies the signal using an in-built programmable gain amplifier (PGA) prior to outputting the digital data to processor 1484. The ADC 1420 in some embodiments is used with vibration transducer 260 to measure differential voltage proportional to the induced velocity. ADC 1420 may be a low-noise digitiser. ADC 1420 may be configured for high gain. ADC 1420 may be configured with a gain factor above 4, 8, 16, 32, or 64, for example. ADC 1420 may be configured for low sampling rate. ADC 1420 may be configured for a sampling rate less than 30, 50, 100, 125, or 200 samples per second, for example. ADC 1420 may be 32-bit ADC, such as ADS 1263 from Texas Instruments. In some other embodiments, ADC 1420 is another type of ADC such as 24-bit ADC or 16-bit ADC, configured for low noise. The data acquisition unit 110 may comprise a high- sensitivity, low-natural frequency (e.g., 2 Hz) geophone element with a low-noise digitizer 1420. This results in a self-noise floor that is more than 30 dB lower below 5 Hz than other data acquisition nodes that are commonly used in industry.

[0249] In some embodiments, the electronic components are chosen for their low- power consumption and capability. Components may be chosen optimal to the design rather than being limited to commercial modules. In addition, the PCBA may be designed to consume as little power as possible to extend its battery life in the field.

[0250] Programmer / debugger unit may be implemented in hardware and / or software to assist analysis of errors in components and / or subsystems of data acquisition unit 110, such as processor 1484. A programmer / debugger unit may be communicativelycoupled to processor 1484 and / or serial module 1474. In some embodiments, data acquisition unit 110 does not comprise a programmer / debugger unit, but instead comprises external port connections, such as debugging port 276 and debugging connector 1472, so that external devices can communicate with processor 1484 and perform programming and / or debugging functions.

[0251] The printed circuit board of second printed circuit board assembly 255 may mount connectors 1430, processor 1485, modem connector 1490, led connector 1470, one or more second PCB connection points 1413, and / or debugging connector 1472. Printed circuit board 320 may also comprise of a voltage regulator / converter.

[0252] Connectors 1430 may provide an interface from cabled connections from power source 240, charge port 278, and / or charge port 274 to components and / or wires on second printed circuit board assembly 255.

[0253] Modem connector 1490 may provide an interface from cabled connection from satellite modem 290 and / or modem port 535 to components and / or wires on second printed circuit board assembly 255.

[0254] LED connector 1470 may provide an interface from cabled connection from LED indicator 272 to components and / or wires on second printed circuit board assembly 255.

[0255] Debugging connector 1472 may provide an interface from cabled connection from debugging port 276 to components and / or wires on second printed circuit board assembly 255.

[0256] According to some other embodiments, the first printed circuit board assembly 250 includes a crystal oscillator 1410. Crystal oscillator 1410 may be communicatively and / or electrically coupled to analogue to digital converter 1420. Crystal oscillator 1410 may provide a stable clock input to the ADC 1420, at a much higher rate than the ADCs 1420 sampling rate.

[0257] According to some other embodiments, the second printed circuit board assembly 255 includes removable auxiliary memory 1445. Removable auxiliary memory 1445 may also be referred to as expandable memory 1445. In some embodiments, removable auxiliary memory 1445 may allow data acquisition unit 110 storage for retransmission, back-up and / or recovery. Removable auxiliary memory 1445 may be an attachable memory source, such as an SD-card or flash memory. In some embodiments, removable auxiliary memory 1445 is a micro-SD card. Removable auxiliary memory 1445 may be housed and / or connectable in an expandable memory reader mounted on printed circuit board assembly 255 and / or 250.

[0258] Removable auxiliary memory 1445 may be used to store pre-processed data as it is batched and before it is transmitted via the modem 290. Removable auxiliary memory 1445 may be configured to store no more than 2 to 10 days of pre-processed data and / or a full battery charge worth of data sampling and transmission.

[0259] Processor 1484 may store a copy of the pre-processed data in removable auxiliary memory 1445, and maintain pre-processed data as a contingency in the case that there is a problem with transmitting some or all of the pre-processed data to the satellite 130, backhaul communications, modem 290, or server system 150, etc. The pre-processed data can then be downloaded via the debugging port 1472 of the data acquisition unit 110 by a user / field operator, for example, when the data acquisition units 110 have been collected from the field. Therefore, the storage of copied pre- processed data in removable auxiliary memory 1445 can aid data recovery after communication / component failure. In some embodiments, storage of copied pre- processed data can be accessed by processor 1484 for re-transmission of the pre- processed data after communication and / or component failure.

[0260] According to some other embodiments, printed circuit board 255 includes an auxiliary processor 1485. Processor 1485 may form part of a processing unit including processor 1484. Processor 1485 may be communicatively coupled to processor 1484 and components on printed circuit board assembly 255, such as removable auxiliary memory 1445, for example. Processor 1485 may handle communications betweenprocessor 1484 (or the processing unit), modem 290, and removable auxiliary memory 1445, for example. Processor 1485 may also provide additional processing and / or application software to assist processor 1484.

[0261] According to some other embodiments, printed circuit board assembly 255 includes one or more dual in-line package (DIP) switches 1460. The DIP switches 1460 are communicatively coupled to devices, such as processor 1485 and / or processor 1484. The DIP switches 1460 may be configured and / or configurable to alter the operating state and / or control operation of processor 1485 and / or processor 1484. For example. The DIP switches 1460 may be configured to boot-up processor 1485 and / or processor 1484 in a different mode or configuration without having to reflash a different firmware image.

[0262] Figures 17A and 17B show schematic diagrams of electronic components of data acquisition unit 110 according to some embodiments.

[0263] As described above, the electronic components of data acquisition unit 110 may include analogue to digital converter 1420, vibration transducer 260, processor 1484, serial module 1474, DIP switches 1460, inertial measurement unit 1450, GNSS unit 1494, power source 240, and first PCB connection points 1414, as shown in Figure 15A.

[0264] In some embodiments, the electronic components of data acquisition unit 110 also include LED indicators 272, debugging connector 1472, processor 1485, removable auxiliary memory 1445, modem connector 1490, second PCB connection point 1413, and connectors 1430, as shown in Figure 15B.

[0265] If the orientation of the data acquisition unit 110 has been manipulated at any time due to external disturbances (wind, rain, animals, etc.) then it will impact the sensitivity of the vibration transducer 260 and thus the data quality. Inertial measurement unit 1450 may be used to determine the orientation and / or the attitude of the data acquisition unit 110 after it is deployed. The orientation measured by inertialmeasurement unit 1450 can be signalled to the processing unit. The processing unit can then send the orientation information reporting as a part of a health or status data payload in a signal to be transmitted by satellite modem 290 over satellite to be received by server system 150 and then visualised on a user device, for example, client device 160. This allows a user / technician to go out and resolve the problem only when needed, mitigating the risks and costs of having somebody in the field manually inspecting the data acquisition units 110. In some embodiments, server system 150 is configured to transmit to client device 160 a current and / or historical measurement of the attitude or orientation of data acquisition unit 110 based on a determination of one or more health or status data payloads received from data acquisition unit 110.

[0266] In some embodiments, server system 150 is configured to transmit to client device 160 an alert to client device 160 indicating a change of the attitude or orientation and / or an amount of change of the attitude or orientation of data acquisition unit 110 to a previous attitude or orientation of the data acquisition unit 110, based on a determination from two or more health or status data payloads received from data acquisition unit 110.

[0267] Figures 15A, 15B, 15C, and 16 show some example 3-D sub-surface imaging. The sub-surface imaging may be through ambient noise tomography processing. The sub-surface imaging is based on seismic data acquired by data acquisition unit 110, for ambient noise tomography processing by server system 150, without the use of active seismic sources and / or stimulated responses. The sub-surface imaging may be based on seismic data acquired by a plurality of data acquisition units 110 of data acquisition array 115, for ambient noise tomography processing by server system 150, without use of active seismic sources and / or stimulated responses.

[0268] Sub-surface imaging may be performed by server system 150 upon receiving preprocessed data from one or more data acquisition units 110 of data acquisition array 115. Representations and modelling of this imaging may be viewable on client computing device 160.

[0269] Figure 15A shows a gravity method survey yielding a false positive result.This is in contrast to an ambient noise tomography method of Figure 15B over the same sub-surface yielding a correct determination of anomalies. Figure 15B is an example two-dimensional (2-D) splice of a 3-D model. Use of ambient noise techniques may allow dense bodies (typical sources of iron oxide copper-gold, or lithium, for example) to be identified.

[0270] In some embodiments, the data acquisition units 110 of data acquisition array 115 may be deployed in different configurations. In some embodiments, the survey area for imaging may be dependent upon the boundary defined by a perimeter of data acquisition units 110 of the data acquisition array 115. In some embodiments, the data acquisition units 110 may be deployed in an evenly spaced rectangular formation with the imaging area a perimeter boundary defined by the outside data acquisition units 110. In some other embodiments, the data acquisition units 110 of data acquisition array 115 are not all evenly spaced from one another. In some other embodiments, the data acquisition units 110 of data acquisition array 115 are not deployed in a rectangular formation but another arrangement.

[0271] In some embodiments, data acquisition units 110 of data acquisition array 115 may be deployed at an equal or near equal distance from one another. In some embodiments, data acquisition units 110 may be deployed at a distance of about 20 metres to about 2 kilometres. In some embodiments, data acquisition units 110 may be deployed at a distance of about 30 metres to about 100 metres, about 100 metres to about 500 metres, or 500 metres to about 1.5 kilometres, for example. In some embodiments, data acquisition units 110 may be deployed at a distance of about 20 metres, 50 metres, 100 metres, 200 metres, 400 metres, 600 metres, 800 metres, 1 kilometre, 1.2 kilometres, 1.5 kilometres, or about 2 kilometres from one another, for example.

[0272] The spacing of the deployed data acquisition units 110 in data acquisition array 115 may influence the depth of imaging. The depth of imaging may be proportional to the spacing distance of the data acquisition units 110 of data acquisitionarray 115. In some embodiments, the depth of imaging may be about 5 times the spacing distance between each of the data acquisition units 110 of data acquisition array 115. The greater the spacing distance between data acquisition units 110 of data acquisition array, the greater the depth of the imaging. However, a greater spacing may lead to a decrease in image resolution.

[0273] In some embodiments, an adequate amount of ground-movement data from one or more data acquisition units 110 of data acquisition array 115 may be collected for server system 150 to generate a display of a first ground region on the user interface, and then at least one of the plurality of data acquisition units 110 may be repositioned at surface locations across a second ground region. Then at least one of the plurality of data acquisition units 110 is configured to collect a second amount of ground-movement data for a display of the second ground region before the power source 240 or supply requires recharging or replacing.

[0274] In some embodiments, the second amount of ground-movement data is an adequate amount of data collected for server system 150 to generate a display of the second ground region on the user interface.

[0275] In some embodiments, the data acquisition units 110 are repositioned from the first ground region to the second ground region at least in part by vehicular transport.

[0276] In some embodiments, a further one or more data acquisition units 110 are deployed in the first ground region whilst server system 150 is receiving pre-processed ground movement data and / or performing ambient noise tomography and / or generating tomography data and / or generating the display. The server system 150 is then configured to receive and process further pre-processed ground movement data from the further data acquisition units 110 and perform ambient noise tomography and generate tomography data based on both the pre-processed ground movement data and the further pre-processed ground movement data. In some embodiments, one or more data acquisition units 110 of data acquisition array 115 in the first ground region are moved to another location within the first ground region whilst sampling is occurring,and the server system 150 is then configured to receive and process the new pre- processed ground movement data from the repositioned data acquisition units 110 and the stagnant data acquisition units 110 and perform ambient noise tomography and generate tomography data from the data sampled from the data acquisition array 115.

[0277] Therefore, some embodiments relate to a method of data acquisition performed by a data acquisition system 100, the data acquisition system 100 including one or more of the data acquisition units 110 or 2110 according to embodiments of the present disclosure. The method may comprise: positioning one or more of the data acquisition units 110 or 2210 at spaced surface locations across a ground region; and operating each of the one or more data acquisition units 110 or 2210 to receive vibrations over a plurality of days; wherein the one or more of data acquisition units 110 or 2210 are operable to generate and send processed data based on vibrations received by the one or more data acquisition units 100 at the spaced surface locations. The operating may include continuous operation of the one or more data acquisition units 110 or 2210 to receive vibrations. The operating may include continuous operation of the one or more data acquisition units 110 or 2210 to receive vibrations for a period of between 4 and 10 days, wherein a power supply 240 or power source 240 of each of the one or more data acquisition units 110 or 2210 is contained within the housing 220 of each of the one or more data acquisition units 110 or 2210 and is configured to supply power for operation of the respective data acquisition unit 110 or 2210 for more than 10 days. The data acquisition system 100 includes one or more satellites 130, one or more ground stations 140, and a server system 150, and wherein the one or more data acquisition units 110 or 2210 are operable to generate and send the processed data, via the one or more satellites 130 and one or more ground stations 140, to a server system 150 for performing computed tomography of the subsurface of the ground region.

[0278] Figure 18 shows an example computer system 1800. In particular embodiments, one or more computer systems 1800 perform one or more steps of one or more methods described or illustrated herein. In particular embodiments, one or more computer systems 1800 provide functionality described or illustrated herein. Inparticular embodiments, software running on one or more computer systems 1800 performs one or more steps of one or more methods described or illustrated herein or provides functionality described or illustrated herein. Particular embodiments include one or more portions of one or more computer systems 1800. Herein, reference to a computer system may encompass a computing device, and vice versa, where appropriate. Moreover, reference to a computer system may encompass one or more computer systems, where appropriate. The server system 150, tomography module 154, data visualisation module 156, data storage 152, and / or client computing device 160 may incorporate a subset or all of the computing components described with reference to the computer system 1800 to provide the functionality described in this specification.

[0279] This disclosure contemplates any suitable number of computer systems 1800 to implement each of the server system 150, tomography system 154, data visualisation system 156, data storage 152, and / or client computing device 160. Computer system 1800 may be an embedded computer system, a system-on-chip (SOC), a single-board computer system (SBC) (such as, for example, a computer-on-module (COM) or system-on-module (SOM)), a desktop computer system, a laptop or notebook computer system, an interactive kiosk, a mainframe, a mesh of computer systems, a mobile telephone, a personal digital assistant (PDA), a server, a tablet computer system, or a combination of two or more of these. Where appropriate, computer system 1800 may include one or more computer systems 1800; be unitary or distributed; span multiple locations; span multiple machines; span multiple data centres; or reside in a cloud, which may include one or more cloud components in one or more networks. Where appropriate, one or more computer systems 1800 may perform without substantial spatial or temporal limitation one or more steps of one or more methods described or illustrated herein. As an example, and not by way of limitation, one or more computer systems 1800 may perform in real-time or in batch mode one or more steps of one or more methods described or illustrated herein. One or more computer systems 1800 may perform at different times or at different locations one or more steps of one or more methods described or illustrated herein, where appropriate.

[0280] In particular embodiments, computer system 1800 includes a processor 1802, memory 1804, storage 1806, an input / output (I / O) interface 1808, a communication interface 1810, and a bus 1812. Although this disclosure describes and illustrates a particular computer system having a particular number of particular components in a particular arrangement, this disclosure contemplates any suitable computer system having any suitable number of any suitable components in any suitable arrangement.

[0281] In particular embodiments, processor 1802 includes hardware for executing instructions, such as those making up a computer program. As an example, and not by way of limitation, to execute instructions, processor 1802 may retrieve (or fetch) the instructions from an internal register, an internal cache, memory 1804, or storage 1806; decode and execute them; and then write one or more results to an internal register, an internal cache, memory 1804, or storage 1806. In particular embodiments, processor 1802 may include one or more internal caches for data, instructions, or addresses. This disclosure contemplates processor 1802 including any suitable number of any suitable internal caches, where appropriate. As an example, and not by way of limitation, processor 1802 may include one or more instruction caches, one or more data caches, and one or more translation lookaside buffers (TLBs). Instructions in the instruction caches may be copies of instructions in memory 1804 or storage 1806, and the instruction caches may speed up retrieval of those instructions by processor 1802. Data in the data caches may be copies of data in memory 1804 or storage 1806 for instructions executing at processor 1802 to operate on; the results of previous instructions executed at processor 1802 for access by subsequent instructions executing at processor 1802 or for writing to memory 1804 or storage 1806; or other suitable data. The data caches may speed up read or write operations by processor 1802. The TLBs may speed up virtual-address translation for processor 1802. In particular embodiments, processor 1802 includes one or more internal registers for data, instructions, or addresses. This disclosure contemplates processor 1802 including any suitable number of any suitable internal registers, where appropriate. Where appropriate, processor 1802 may include one or more arithmetic logic units (ALUs); be a multi-core processor; or include one or more processors 1802. Although thisdisclosure describes and illustrates a particular processor, this disclosure contemplates any suitable processor.

[0282] In particular embodiments, memory 1804 includes main memory for storing instructions for processor 1802 to execute or data for processor 1802 to operate on. As an example, and not by way of limitation, computer system 1800 may load instructions from storage 1806 or another source (such as, for example, another computer system 1800) to memory 1804. Processor 1802 may then load the instructions from memory 1804 to an internal register or internal cache. To execute the instructions, processor 1802 may retrieve the instructions from the internal register or internal cache and decode them. During or after execution of the instructions, processor 1802 may write one or more results (which may be intermediate or final results) to the internal register or internal cache. Processor 1802 may then write one or more of those results to memory 1804. In particular embodiments, processor 1802 executes only instructions in one or more internal registers or internal caches or in memory 1804 (as opposed to storage 1806 or elsewhere) and operates only on data in one or more internal registers or internal caches or in memory 1804 (as opposed to storage 1806 or elsewhere). One or more memory buses (which may each include an address bus and a data bus) may couple processor 1802 to memory 1804. Bus 1812 may include one or more memory buses, as described below. In particular embodiments, one or more memory management units (MMUs) reside between processor 1802 and memory 1804 and facilitate accesses to memory 1804 requested by processor 1802. In particular embodiments, memory 1804 includes random access memory (RAM). This RAM may be volatile memory, where appropriate. Where appropriate, this RAM may be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, where appropriate, this RAM may be single-ported or multi-ported RAM. This disclosure contemplates any suitable RAM. Memory 1804 may include one or more memories 1804, where appropriate. Although this disclosure describes and illustrates particular memory, this disclosure contemplates any suitable memory.

[0283] In particular embodiments, storage 1806 includes mass storage for data or instructions. As an example, and not by way of limitation, storage 1806 may include ahard disk drive (HDD), a floppy disk drive, flash memory, an optical disc, a magnetooptical disc, magnetic tape, or a Universal Serial Bus (USB) drive or a combination of two or more of these. Storage 1806 may include removable or non-removable (or fixed) media, where appropriate. Storage 1806 may be internal or external to computer system 1800, where appropriate. In particular embodiments, storage 1806 is non-volatile, solid-state memory. In particular embodiments, storage 1806 includes read-only memory (ROM). Where appropriate, this ROM may be mask-programmed ROM, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM), or flash memory or a combination of two or more of these. This disclosure contemplates mass storage 1806 taking any suitable physical form. Storage 1806 may include one or more storage control units facilitating communication between processor 1802 and storage 1806, where appropriate. Where appropriate, storage 1806 may include one or more storages 1806. Although this disclosure describes and illustrates particular storage, this disclosure contemplates any suitable storage.

[0284] In particular embodiments, I / O interface 1808 includes hardware, software, or both, providing one or more interfaces for communication between computer system 1800 and one or more I / O devices. Computer system 1800 may include one or more of these I / O devices, where appropriate. One or more of these I / O devices may enable communication between a person and computer system 1800. As an example, and not by way of limitation, an I / O device may include a keyboard, keypad, microphone, monitor, mouse, printer, scanner, speaker, still camera, stylus, tablet, touch screen, trackball, video camera, another suitable RO device or a combination of two or more of these. An I / O device may include one or more sensors. This disclosure contemplates any suitable I / O devices and any suitable I / O interfaces X08 for them. Where appropriate, I / O interface 1808 may include one or more device or software drivers enabling processor 1802 to drive one or more of these I / O devices. I / O interface 1808 may include one or more I / O interfaces 1808, where appropriate. Although this disclosure describes and illustrates a particular I / O interface, this disclosure contemplates any suitable I / O interface.

[0285] In particular embodiments, communication interface 1810 includes hardware, software, or both providing one or more interfaces for communication (such as, for example, packet-based communication) between computer system 1800 and one or more other computer systems 1800 or one or more networks. As an example, and not by way of limitation, communication interface 1810 may include a network interface controller (NIC) or network adapter for communicating with an Ethernet or other wirebased network or a wireless NIC (WNIC) or wireless adapter for communicating with a wireless network, such as a WI-FI network. This disclosure contemplates any suitable network and any suitable communication interface 1810 for it. As an example, and not by way of limitation, computer system 1800 may communicate with an ad hoc network, a personal area network (PAN), a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), or one or more portions of the Internet or a combination of two or more of these. One or more portions of one or more of these networks may be wired or wireless. As an example, computer system 1800 may communicate with a wireless PAN (WPAN) (such as, for example, a BLUETOOTH WPAN), a WI-FI network, a WLMAX network, a cellular telephone network (such as, for example, a Global System for Mobile Communications (GSM) network), or other suitable wireless network or a combination of two or more of these. Computer system 1800 may include any suitable communication interface 1810 for any of these networks, where appropriate. Communication interface 1810 may include one or more communication interfaces 1810, where appropriate. Although this disclosure describes and illustrates a particular communication interface, this disclosure contemplates any suitable communication interface.

[0286] In particular embodiments, bus 1812 includes hardware, software, or both coupling components of computer system 1800 to each other. As an example and not by way of limitation, bus 1812 may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a frontside bus (FSB), a HYPERTRANSPORT (HT) interconnect, an Industry Standard Architecture (ISA) bus, an INFINIBAND interconnect, a low-pin-count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCIe) bus, a serial advanced technologyattachment (SATA) bus, a Video Electronics Standards Association local (VLB) bus, or another suitable bus or a combination of two or more of these. Bus 1812 may include one or more buses X12, where appropriate. Although this disclosure describes and illustrates a particular bus, this disclosure contemplates any suitable bus or interconnect.

[0287] Herein, a computer-readable non-transitory storage medium or media may include one or more semiconductor-based or other integrated circuits (Ics) (such, as for example, field-programmable gate arrays (FPGAs) or application- specific Ics (ASICs)), hard disk drives (HDDs), hybrid hard drives (HHDs), optical discs, optical disc drives (ODDs), magneto-optical discs, magneto-optical drives, floppy diskettes, floppy disk drives (FDDs), magnetic tapes, solid-state drives (SSDs), RAM-drives, SECURE DIGITAL cards or drives, any other suitable computer-readable non-transitory storage media, or any suitable combination of two or more of these, where appropriate. A computer-readable non-transitory storage medium may be volatile, non-volatile, or a combination of volatile and non-volatile, where appropriate.

[0288] Figure 19 shows a cross-sectional view of data acquisition unit 110 according to some other embodiments.

[0289] In some embodiments, the satellite modem 290 is encased in the housing 220. In some embodiments, the data acquisition unit 110 includes the satellite modem 290 within the upper part 223. Satellite modem 290 may be encased in upper part 223. The upper part 223 may be configured to house part or all of the satellite modem 290. Accordingly, in some embodiments, the upper part may be taller or extend higher than the upper part 223 shown in Figure 2, in order to house the satellite modem 290. Upper part 223 may include a recess 1991 to house the satellite modem 290. The recess 1991 to house the satellite modem 290 may be centrally located in upper part 223. The recess 1991 to house the satellite modem 290 may be defined at least in part by an underside surface of upper part 223. Recess 1991 may be referred to as a mounting portion 1991. Therein, satellite modem 290 may be attached in the mounting portion 1991. In some embodiments, satellite modem 290 may be inserted into the recess 1991, and then besealed via gasket or stopper 1923. Stopper 1923 may include a recess for locating satellite modem communication port 771. Stopper 1923 may include the recess for locating cabling to / from satellite modem communication port 771. Upper part 223 may house satellite modem 290 for protecting satellite modem 290 from water ingress for ingress protection (IP) rating of 67 or 68.

[0290] The location of satellite modem 290 in embodiments illustrated by Figure 19 may be relatively the same with respect to at least one of: the component mounting structure 230, power source 240, vibration transducer 260, or vibration sensing portion 227, when compared with other embodiments of the present disclosure, such as the data acquisition unit 110 shown in Figure 12. In some embodiments, location of modem 290 may be relatively the same with respect to the component mounting structure 230, power source 240, vibration transducer 260, and vibration sensing portion 227, when compared with other embodiments of the present disclosure, such as the data acquisition unit 110 shown in Figure 12.

[0291] Figure 20 shows an exploded view of data acquisition unit 2110 according to some embodiments. Figure 29 shows an exploded view of the modem 290, component mounting structure 2230, and electronics of data acquisition unit 2110 according to some embodiments.

[0292] Data acquisition unit 2110 may exemplify data acquisition unit 110 according to some other embodiments. Some embodiments of data acquisition unit 110 and 2110 may possess different features in their exemplified description and / or visual representation in exemplified Figures. However, these different embodiments do not preclude the combining of disclosed features of data acquisition units 110 and / or 2110, as would readily be understood by the skilled person of the art. The different features of exemplified description and / or visual representations in the exemplified Figures of data acquisition units 110 and 2110 are for exemplifying different embodiments of the data acquisition unit according to the present disclosure. This compatibility of embodiments may be applicable for various features, including but not limited to: identically numerated features and features of different numeration but the same name, such ashousing 220 and housing 2220, upper part 223 and upper part 2223, lower part 226 and lower part 2226, transducer holding structure 926 and transducer holding structure 3926, component mounting structure 230 and component mounting structure 2230, and power source 240 and power source 2240, for example.

[0293] Data acquisition unit 2110 includes housing 2220. Housing 2220 may be referred to as external housing 2220 or first housing 2220. The housing 2220 may include an upper part 2223. Upper part 2223 may be referred to as upper body 2223 or modem integration module body 2223. The housing 2220 may include a lower part 2226. Lower part 2226 may be referred to as lower body 2226 or geological instrument module body 2226. The housing 2220 includes a central chamber. In some embodiments, upper part 2223 and lower part 2226 define the central chamber. In some embodiments, upper part 2223 and lower part 2226 are attachable together to define the central chamber. Data acquisition unit 2110 is self-contained when assembled.Similarly to data acquisition unit 110, data acquisition unit 2110 is configured for performing passive seismic monitoring.

[0294] In some embodiments, housing 2220, upper part 2223, and lower part 2226 are the same components / features as housing 220, upper part 223, and lower part 226.

[0295] In some embodiments, upper part 2223 does not include an upper part flange 225, nor does lower part 2226 include a lower part flange 228.

[0296] In some embodiments, lower part 2226 is free of a vibration sensing portion 227 projection.

[0297] As shown in Figure 20, data acquisition unit 2110 may include a sealing element 2022. Upper part 2223 and lower part 2226 may be sealed via the sealing element 2022. The sealing element 2022 may be an o-ring 2022. Upper part 2223 and lower part 2226 may be sealed via compressing the sealing element 2022. Upper part 2223 and lower part 2226 may be sealed via a tongue and groove mechanism.

[0298] As shown in Figure 20, data acquisition unit 2110 may include a vibration transducer 260 in housing 2220. Similarly with data acquisition unit 110, vibration transducer 260 may be configured to receive vibrations via the housing 2220 and generate an output signal based on the received vibrations.

[0299] As shown in Figures 20 and 29, data acquisition unit 2110 may include a component mounting structure 2230. In some embodiments, the walls of component mounting structure 2230 may be substantially prism shaped, such as rectangular prism shaped. In some embodiments, component mounting structure 2230 includes the same component(s) as component mounting structure 230. Component mounting structure 2230 may be received in the central chamber formed by housing 2220. Component mounting structure 2230 may be coupled to the housing 2220. Component mounting structure 2230 may be attached and / or coupled to one or more inside portions of upper part 2223 of housing 2220.

[0300] Component mounting structure 2230 may comprise an internal housing with an internal chamber. The internal housing of component mounting structure 2230 may be referred to as second housing or sub-housing. The internal housing of component mounting structure 2230 may be configured to receive a power source 2240 within the internal chamber of the internal housing.

[0301] As shown at least in Figures 20, 24B, and 26, component mounting structure 2230 may include modem port 535. Modem port 535 may be located on a side face of the component mounting structure 2230. Modem port 535 may be located on a lower side portion of the component mounting structure 2230. Modem port 535 may be proximate to modem 290.

[0302] As shown in Figures 20 and 29, data acquisition unit 2110 includes a ground plane 2090. As shown in Figure 20. Ground plane 2090 may be mounted on component mounting structure 2230. Ground plane 2090 may be configured as a reflecting surface for radio waves. Ground plane 2090 may comprise a material suitable for reflectingelectromagnetic waves such as steel, copper, or aluminium, for example. Ground plane 2090 may comprise aluminium 5052-H34.

[0303] Data acquisition unit 2110 may include satellite modem 290 disposed in the housing 2220. Satellite modem 290 may be mounted on ground plane 2090 as shown in Figure 20. Ground plane 2090 may be configured to improve the performance of modem 290. Ground plane 2090 may be configured to improve the signal-to-noise ratio or carrier-to-noise ratio of modem 290. In some embodiments, ground plane 2090 is used to secure power source 2240 in internal housing of component mounting structure 2230. In some other embodiments, satellite modem 290 is mounted on component mounting structure 2230. In some other embodiments, data acquisition unit 2110 does not include ground plane 2090. In some embodiments, ground plane 2090 is used with an Orbcomm ST2100 modem 290.

[0304] As shown in Figure 29, data acquisition unit 2110 may include a padding 2940 for power source 2240. Padding 2940 may be 2 to 4 mm thick. In some embodiments, padding 2940 is 3 mm thick. Padding 2940 may be foam tape. Padding 2940 may comprise rubber. Padding 2940 may comprise a synthetic rubber, for example ethylene propylene diene monomer (EPDM) rubber. Padding 2940 may substantially cover the surface area of power source 2240. Power source 2240 may be sheathed within padding 2940. Padding 2940 may provide mechanical insulation.

[0305] As shown in Figures 20 and 29, data acquisition unit 2110 includes an antenna 580. As shown in Figure 29, antenna 580 may be a monopole antenna, such as a Taoglas monopole antenna. As shown in Figure 20, ground plane 2090 may be configured to mount antenna 580. Accordingly, antenna 580 may be mounted on ground plane 2090.

[0306] In some embodiments, the electromagnetic reflective properties of ground plane 2090 configured by the physical design of ground plane 2090 may assist the effective simultaneous operation of both antenna 580 and modem 290 mounted on ground plane 2090. In some other embodiments, the electromagnetic reflectiveproperties of ground plane 2090 configured by the physical design of ground plane 2090 may assist the effective simultaneous operation of both modem 290 mounted on ground plane 2090 and antenna 580 mounted within housing 2220.

[0307] Component mounting structure 2230 may comprise outer side faces for mounting one or more printed circuit board (PCB) assemblies. The one or more PCBAs may be configured for bearing the processor 1484 and the synchronisation unit 1494.As shown in Figures 20 and 29, data acquisition unit 2110 may also include first PCB A 250 and second PCBA 255. Component mounting structure 2230 may be configured to mount first PCBA 250 and second PCBA 255. Component mounting structure 2230 may include fasteners, such as press fit nuts or other mechanical connectors, for mounting the PCBAs 250 and 255 via stand-offs or spacers. Accordingly, first PCBA 250 and second PCBA 255 may be mounted on component mounting structure 2230. First PCBA 250 and second PCBA 255 may be mounted on two opposite outer side faces of the component mounting structure 2230. The first PCBA 250 may bear the processor 1484 and the synchronisation unit 1494.

[0308] As shown in Figure 29, data acquisition unit 2110 includes electromagnetic shielding structure 2450, which may be referred to as shielding structure 2450, shielding 2450, or PCBA shielding structure 2450. Shielding structure 2450 may be configured to cover first PCBA 250 and / or second PCBA 255. As shown in Figures 29 and 32, shielding structure 2450 may be configured to cover first PCBA 250. Component mounting structure 2230 may be configured to mount shielding structure 2450. Accordingly, shielding structure 2450 may be mounted on component mounting structure 2230 to form a shielding housing to enclose PCBA 250. Shielding structure 2450 may include one or more recess to allow cabling to / from housed PCBA 250.Shielding structure 2450 may comprise copper, aluminium, brass, tin, nickel, and / or phosphor bronze. Shielding structure 2450 may comprise aluminium 6061-T6.

[0309] Shielding structure 2450 may be prism shaped. Shielding structure 2450 may be mounted to have a gap of about 3 to 30 mm between the inner surface of the shielding structure 2450 and the board of its housed PCBA. First PCBA 250 andsecond PCBA 255 may assume various shapes in various embodiments. In some embodiments, first PCBA 250 and / or second PCBA 255 may be round as shown in the exemplified Figures, square, semi-circular, or rectangular, for example. Accordingly, shielding structure 2450 may be prism shaped with round (as shown in the exemplified Figures), square, semi-circular, or rectangular cross-section, for example.

[0310] PCBA 250 may have a diameter or length of between about 50 to 120 mm, for example. According to some embodiments, PCBA 250 may have a diameter or length between about 50 to 80 mm, 70 to 90 mm, or 75 to 100 mm. In some embodiments, PCBA 250 may have a diameter or length between about 70 to 75 mm, 75 to 80 mm, 80 to 85 mm, 85 to 90 mm, 90 to 95 mm, or 95 to 100 mm. In some embodiments, PCBA 250 may have a diameter or length of about 70, 75, 80, 85, 90, or 95 mm. In some embodiments, PCBA 250 may have a diameter or length of about 80 mm.

[0311] PCBA 255 may have a diameter or length of between about 70 to 130 mm, for example. According to some embodiments, PCBA 255 may have a diameter or length between about 80 to 100 mm, 90 to 110 mm, or 95 to 125 mm. In some embodiments, PCBA 255 may have a diameter or length between about 90 to 95 mm, 95 to 100 mm, 100 to 105 mm, 105 to 110 mm, 110 to 115 mm, or 115 to 120 mm. In some embodiments, PCBA 255 may have a diameter or length of about 90, 95, 100, 105, 110, or 115 mm. In some embodiments, PCBA 255 may have a diameter or length of about 100 mm.

[0312] Data acquisition unit 2110 may include a level indicator 270, charge port or user input 274, debugging port 276, charge port 278, or LED indicator 272.

[0313] Data acquisition unit 2110 may include a handle 2521. Handle 2521 may be fixed to upper part 2223. Handle 2521 may be fixed to the top surface of upper part 2223. As shown in Figures 20, 21, 22, and 23, handle 2521 may be fixed on or near opposite edges on top surface of upper part 2223. As shown in Figures 20, 21, 22, and 23, handle 2521 may include a rope. As shown in Figures 20, 21, 22, and 23, handle 2521 may include a grip element. Handle 2521 may help a field technician to carry dataacquisition unit 2110 when held. Handle 2521 may assist a field technician to extract data acquisition unit 2110 from the ground when pulled.

[0314] Figure 21 shows an external perspective view of data acquisition unit 2110 according to some embodiments. More specifically, Figure 21 shows an external perspective view of housing 2220 of data acquisition unit 2110 when assembled, according to some embodiments.

[0315] As shown in Figure 21, the shape of the housing 2220 may be substantially prism shaped, cylindrical, and / or hexagonal prism shaped.

[0316] The housing 2220 may be configured to form a polyhedron like shape wherein a plurality of substantially vertical edges of the housing each include one or more concave indentations.

[0317] Upper part 2223 may include a substantially prism, cylindrical, and / or hexagonal prism shaped. The upper part 2223 may not taper to lower part 2226. In some embodiments, the upper part 2223 may have a substantially uniform width at different vertical localities.

[0318] A plurality of substantially vertical edges of the upper part 2223 include concave indentations 2523. Concave indentations 2523 of upper part 2223 may improve operator handling of data acquisition unit 2110. A plurality of vertices of the upper part 2223 include concave indentations 2523. As shown in Figure 21, a plurality of substantially vertical edges and / or vertices of the upper part 2223 include concave indentations 2523. Each of the substantially vertical edges and / or vertices of the upper part 2223 may include concave indentations 2523.

[0319] Lower part 2226 may include a substantially prism, cylindrical, and / or hexagonal prism shaped upper portion. The upper portion of lower part 2226 may not taper to a lowermost portion of lower part 2226. In some embodiments, the upper portion of lower part 2226 may have a substantially uniform width at different verticallocalities. The upper portion of lower part 2226 may form a central portion of housing 2220. As shown in Figure 21, lower part 2226 may be longer (i.e. of greater height) than upper part 2223. In some embodiments, lower part 2226 may be about 1.5 to 6 times the length (height) than upper part 2223. In some embodiments, lower part 2226 may be about 3 times the length (height) than upper part 2223. Accordingly, a central portion of housing 2220 may comprise upper portion of lower part 2226, a portion of upper portion of lower part 2226, and / or a portion of lowermost portion of lower part 2226.

[0320] Lower part 2226 may include a substantially prism, cylindrical, and / or hexagonal prism shaped lowermost portion. As shown in Figures 20, 21, 22 and 31, the lowermost portion of lower part 2226 includes a base 2228. The base 2228 may be substantially flat and be referred to as flattened base 2228. As shown in Figures 20, 21, 22, 31, and 32 the lowermost portion of lower part 2226 may taper towards the base 2228. Therefore, the width of base 2228 of lower part 2226 may be narrower than the width of upper part 2223 and / or the width of upper portion of lower part 2226. As shown in Figures 20, 21, 22, 31, and 32 the flattened base 2228 of the lowermost portion of lower part 2226, the lower part 2226, and the data acquisition unit 2110 may not include the vibration sensing portion 227 projection. However, the present disclosure is not limited thereto, in some other embodiments, lower part 2226 may include a vibration sensing portion 227 projection. In some embodiments, the base 2228 may include a central projection 227, and / or taper inwardly and downwardly from its outer edges towards a lower central position. Accordingly, the vibration transducer 260 may be located in a low position within housing 2220 that is close to a groundengaging part of the housing 2220. For example, the vibration transducer 260 may be received in a part of the housing 2220 that projects downwardly from a lower surface of the base 2228. Further, the vibration transducer 260 is tightly coupled within housing 2220 for optimal transmission of vibrations from the surrounding soil to the vibration transducer 260 through the housing 2220. The topology of data acquisition unit 2110 is designed for effective coupling of ambient vibrations from the soil into the vibration transducer 260.

[0321] In some embodiments, the lower most portion of lower part 2226 may be about 0.5 to 4 times the length (height) than upper portion of lower part 2226. In some embodiments, the lower most portion of lower part 2226 may be about 1.5 times the length (height) than upper portion of lower part 2226.

[0322] A plurality of substantially vertical edges of the lower part 2226 include concave indentations 2526. Concave indentations 2526 of lower part 2226 may improve operator handling of data acquisition unit 2110. Concave indentations 2526 may improve coupling of data acquisition unit 2110 to soil when deployed. Each of the substantially vertical edges of the lower part 2226 may include concave indentations 2526. As shown in Figure 21, the concave indentations 2526 may span from the upper portion of lower part 2226 to the lowermost portion of lower part 2226. The concave indentations 2526 may span within the upper portion of lower part 2226. The concave indentations 2526 may span within the lowermost portion of lower part 2226.

[0323] Concave indentations 2523 and concave indentations 2526 may be at a same circumferential position on upper part 2223 and lower part 2226 respectively. The concave indentation 2523 and concave indentation 2526 may also each be sloped or shaped so as to form a flange between them, so that one or more fasteners may be inserted within the flange to secure upper part 2223 and lower part 2226. Accordingly, the shape of a cross section of housing 2220 may be convex polygon, such as a hexagon, and due to the indentations 2523 and 2526 the formed flanges and the fasteners binding the upper and lower parts 2223 and 2226 are confined within the cross-sectional boundary. This avoids protruding flanges and improves handling of the data acquisition unit 2110.

[0324] Also, as shown in Figure 21, level indicator 270, FED indicator 272, user input 274, debugging port 276 and charge port 278 may be included on the top surface of upper part 2223 of data acquisition unit 2110. Accordingly, level indicator 270, LED indicator 272, user input 274, debugging port 276 and charge port 278 are examples of peripheral components or “peripherals” of data acquisition unit 2110. In some other embodiments, antenna 580 may not be located inside housing 2220 andinstead is a peripheral component on upper part 2223. The placement of peripherals on the upper part 2223 allows a large portion of the housing 2220 of data acquisition unit 2110 to be buried for better coupling with the soil without compromising the structural integrity, functionality, and / or usefulness of the peripherals on the upper part 2223. Level indicator 270 may be located on a central portion of top surface of upper part 2223.

[0325] Data acquisition unit 2110 may also include a safety valve 2271. Safety valve 2271 may be located on upper part 2223. As shown in Figure 21, safety valve 2271 may be located on the top surface of upper part 2223. Safety valve 2271 may be configured to release an atmosphere and / or substance from inside data acquisition unit 2110. Safety valve 2271 may be configured to activate when a pressure or temperature in data acquisition unit 2110 exceeds a predetermined threshold. Safety valve 2271 may be a pressure release valve 2271. Safety valve 2271 may be or include a one-way pressure release valve 2271, for example.

[0326] Figure 22 shows a side view of data acquisition unit 2110, according to some embodiments.

[0327] The length (height) of data acquisition unit 2110 from top surface of upper part 2223 to base 2228 of lower part 2226 may be referred to as housing height 2236. Housing height 2236 may be between about 170 to 300 mm. According to some embodiments, housing height 2236 is between about 170 to 200 mm, 180 to 220 mm, or 200 to 280 mm. In some embodiments, housing height 2236 is about 175, 180, 185, 190, 195, or 200 mm. In some embodiments, the housing height 2236 is about 185 mm.

[0328] The length (height) of data acquisition unit 2110 from top of an uppermost peripheral to base 2228 of lower part 2226 may be referred to as base to peripheral height 2276. As shown in Figure 22, the uppermost peripheral is debugging port 276. As shown in Figure 22, the base to peripheral height 2276 is longer than housing height 2236, however the present disclosure is not as such limited. Base to peripheral height 2276 may be between about 150 to 330 mm. According to some embodiments, base toperipheral height 2276 is between about 190 to 230 mm, 200 to 250 mm, or 220 to 300 mm. In some embodiments, base to peripheral height 2276 is about 200, 205, 210, 215, 220, or 225 mm. In some embodiments, the base to peripheral height 2276 is about 210 mm.

[0329] Figure 23 shows an overhead view of data acquisition unit 2110 according to some embodiments.

[0330] The width (diameter) of upper part 2223 from a side surface of upper part 2223 to an opposing side surface of upper part 2223 may be referred to as side-to-side width 2320 or side-to-side surface width 2320. In some embodiments, side-to-side width 2320 is the largest width (diameter) of upper part 2223 from a side surface of upper part 2223 to an opposing side surface of upper part 2223. Side-to-side surface width 2320 may be measured at two points on upper part 2223 or lower part 2226 at a same height to each other. Side-to-side surface width 2320 may be between about 140 to 250 mm. According to some embodiments, side-to-side surface width 2320 is between about 150 to 200 mm, 180 to 210 mm, or 190 to 230 mm. In some embodiments, side-to-side surface width 2320 is between about 180 to 185 mm, 185 to 190 mm, 190 to 195 mm, 195 to 200 mm, 200 to 205 mm, or 205 to 210 mm. In some embodiments, side-to-side surface width 2320 is about 180, 185, 190, 195, 200, or 205 mm. In some embodiments, side-to-side surface width 2320 is about 194 mm.

[0331] Side-to-side width 2320 may also or alternatively be the width (diameter) of lower part 2226 from a side surface of lower part 2226 to an opposing side surface of lower part 2226. In some embodiments, side-to-side width 2320 is the largest width (diameter) of lower part 2226 from a side surface of lower part 2226 to an opposing side surface of lower part 2226.

[0332] The width (diameter) of upper part 2223 from a vertical edge or vertices of upper part 2223 to an opposing vertical edge or vertices of upper part 2223 may be referred to as apex width 2310. In some embodiments, apex width 2310 is the largest width (diameter) of upper part 2223 from a vertical edge or vertices of upper part 2223to an opposing vertical edge or vertices of upper part 2223. Apex width 2310 may be measured at two points on upper part 2223 or lower part 2226 at a same height to each other. Apex width 2310 may be between about 170 to 270 mm. According to some embodiments, apex width 2310 is between about 170 to 220 mm, 190 to 240 mm, or 200 to 250 mm. In some embodiments, apex width 2310 is between about 200 to 205 mm, 205 to 210 mm, 210 to 215 mm, 215 to 220 mm, 220 to 225 mm, or 225 to 230 mm. In some embodiments, apex width 2310 is about 200, 205, 210, 215, 220, or 225 mm. In some embodiments, apex width 2310 is about 218 mm.

[0333] Apex width 2310 may also or alternatively be the width (diameter) of lower part 2226 from a vertical edge of lower part 2226 to an opposing vertical edge of lower part 2226. In some embodiments, apex width 2310 is the largest width (diameter) of lower part 2226 from a vertical edge of lower part 2226 to an opposing vertical edge of lower part 2226.

[0334] Figure 24A shows a perspective view from above the component mounting structure 2230 of data acquisition unit 2110 bearing electronics and satellite modem 290 according to some embodiments.

[0335] In particular, Figure 24A shows ground plane 2090, shielding structure 2450, and PCBA 255 mounted on component mounting structure 2230. Figure 24A also shows modem 290 and antenna 580 mounted on ground plane 2090.

[0336] Figure 24A also shows interconnecting PCBA cabling 2455 from PCBA 255 to shielding structure 2450. The interconnecting PCBA cabling 2455 may pass through a recess in shielding structure 2450 to the PCBA 250 enclosed within. Interconnecting PCBA cabling 2455 may be a transmission medium for power and / or data between respective components on PCBAs 250 and 255.

[0337] Figure 24B shows a perspective view from below the component mounting structure 2230 of data acquisition unit 2110 bearing electronics according to some other embodiments.

[0338] In particular, Figure 24B shows ground plane 2090, shielding structure 2450, and PCBA 255 mounted on component mounting structure 2230. Figure 24B also shows antenna 580 mounted on ground plane 2090. Figure 24B also shows power source 2240 held within component mounting structure 2230.

[0339] Figure 25 shows a perspective view of the underside of the upper part 2223 of data acquisition unit 2110, according to some embodiments.

[0340] Upper part 2223 may include an internal upper surface 2540. Internal upper surface 2540 may be an opposite surface of the wall of upper part 2223 which includes the top surface of upper part 2223. Accordingly, internal upper surface 2540 may include respective recesses for allowing components such as level indicator 270, led indicator 272, user input 274, debug port 276, and further port 278 to be mounted to top surface of upper part and permit respective cabling / connection within data acquisition unit 2110.

[0341] Within the underside of upper part 2223, there may be a plurality of mounting portions 2520. As shown in Figure 25, upper part 2223 may include six mounting portions 2520. Mounting portions 2520 may be referred to as outer mounting bosses 2520 or housing bosses 2520. Mounting portions 2520 may be configured for fastening upper part 2223 to lower part 2226. Mounting portion 2520 may comprise structure and a recess within for receiving a fastener for attaching lower part 2226 to upper part 2223. The recess of mounting portion 2520 may be threaded for receiving the fastener. As shown in Figure 25, mounting portion 2520 may be located on an underside of a concave indentation 2523 of upper part 2223. In some embodiments, the recess of mounting portion 2520 may extend from an underside surface of upper part 2223 through a surface of the concave indentation 2523, so that the respective fastener may be inserted from the recess in concave indentation 2523 through the mounting portion 2520 of upper part 2223 through to lower part 2226.

[0342] The structure of mounting portion 2520 may be tubular shaped. The structure of mounting portion 2520 may be surrounded by an inner wall structure 2528 and anouter wall structure 2527 of upper part 2223. The surrounding inner wall structure 2528 and outer wall structure 2527 may form an “eye” shape around the structure of mounting portion 2520. Outer wall structure 2527 may be a portion of walls 2545 of upper part 2223. Inner wall structure 2528 may be a protruding structure from walls 2545. Mounting portion may be connected to the outer wall structure 2527 and / or inner wall structure 2528 by respective ribs 2522. Upper part 2223 and walls 2545 may have a convex polygon shaped cross-section, such as a hexagon, with inner wall structure 2528 and mounting portion 2520 bounded within.

[0343] Within the underside of upper part 2223 there may be a second plurality of mounting portions 2510. Mounting portions 2510 may be referred to as inner mounting bosses 2510 or cradle bosses 2510. As shown in Figure 25, upper part 2223 may include four mounting portions 2510. Mounting portions 2510 may be located closer to a central portion of the internal floor than mounting portions 2520. In some embodiments, mounting portions 2510 may be configured for fastening the component mounting structure 2230 to upper part 2223. In some embodiments, mounting portions 2510 may be configured for fastening the ground plane 2090 to upper part 2223. In some embodiments, mounting portions 2510 may be configured for fastening both component mounting structure 2230 and the ground plane 2090 to upper part 2223. Mounting portion 2510 may comprise structure and a recess within for receiving a fastener for the fastening. The recess of mounting portion 2510 may be threaded for receiving the fastener. Mounting portions 2510 may be connected to walls 2545 by respective ribs 2514.

[0344] Figures 25 and 26 also show a housing seal 3020 around an internal facing circumferential portion of wall 2545. Housing seal 3020 may receive o-ring seal 2022. As shown in Figure 25, the housing seal 3020 may be located upon wall 2545 and pass through an internal facing portion of each inner wall structure 2528. This may mitigate any ingress from the recess of concave indentation 2523 and mounting boss 2520. Housing seal 3020 and o-ring seal 2022 may therefore form a hexagonal shape with concave indentation at its vertices.

[0345] Figure 26 shows a perspective view of the component mounting structure 2230, electronics and upper part 2223 of data acquisition unit 2110 during assembly, according to some embodiments. Figure 26 shows a first sub-assembly 2403 according to some other embodiments. In such other embodiments, first sub-assembly 2403 includes modem 290 (not shown), ground plane 2090, component mounting structure 2230 receiving power source 2240 and bearing first PCBA 250 (not shown) and second PCBA 255, and shielding structure 2450 enclosing first PCBA 250. The first subassembly 2403 may include antenna 580. The first sub-assembly 2403 may be described as an upper sub-assembly or modem integration sub-assembly.

[0346] In particular, Figure 26 shows component mounting structure 2230 including mounted ground plane 2090 with antenna 580, PCBA 255, and shielding structure 2450, wherein the component mounting structure 2230 and ground plane 2090 are secured to mounting portions 2510 of upper part 2223 by fasteners 2610.

[0347] During assembly, the ground plane 2090, PCBAs 250 and 255, and shielding structure 2450 are attached to component mounting structure 2230, and modem 290 is attached to ground plane 2090. Then the component mounting structure 2230 is attached to upper part 2223. The component mounting structure 2230 may be attached to the upper part 2223 upside down, for example, for convenience of assembly. Then one or more of PCBAs 250 or 255 may be connected to vibration transducer 260, and lower part 2226 is attached to upper part 2223. Then one or more of PCBAs 250 or 255 may be connected to vibration transducer 260 via a cable. The cable may be about 10 to 30 cm in length. The cable may be 20 cm in length.

[0348] Figure 27 shows a perspective view of ground plane 2090 according to some embodiments. Figure 28 shows an isometric view of the modem 290 mounted on the ground plane 2090, according to some embodiments.

[0349] Ground plane 2090 may be a variety of shapes according to various embodiments. Ground plane 2090 may be generally flat (planar) and rectangular, square, or circular in shape. Ground plane 2090 may be a simple polygon planar shape.As shown in Figure 27, ground plane 2090 may generally be octagonal in shape. Ground plane 2090 may have two long side edge regions 2795 and two short end edge regions 2798. Ground plane 2090 may have one or more truncation edges 2792. As shown in Figure 27, ground plane 2090 may have four truncation edges 2792.

[0350] Ground plane 2090 may be horizontally oriented when attached on top of component mounting structure 2230. Ground plane 2090 may extend a substantial cross-sectional area within central chamber of closed housing 2220. Outer edges of ground plane 2090 may extend to be proximate and / or in contact with at least one inner wall portion of housing 2220. This may have the effect of mitigating RF interference with the modem 290 from one or more of the PCBAs in the lower part of the housing 2220.

[0351] As shown in Figures 27 and 28, in some embodiments, the ground plane 2090 includes indentations 2794 along one or more edge regions of the ground plane 2090. When data acquisition unit 2110 is assembled, the indentations 2794 along one or more edge regions may form recess between the indented edge and the inner wall of housing to permit passage for cabling. The indentations 2794 along one or more edge regions may permit passage of cabling from a first space 3291 above the ground plane to a second space 3292 below the ground plane. An example first space 3291 and second space 3292 are indicated on Figure 32. As shown in Figures 27 and 28, ground plane 2090 may include five indentations 2794. Ground plane 2090 may include two indentations 2794 on a long side edge region 2795 of ground plane 2090. Ground plane 2090 may include two indentations 2794 on an opposite long side edge region 2795 of ground plane 2090. The long edge indentations 2794 may be suitable for PCBA 250 and / or 255 cabling to peripherals on upper part 2223. Ground plane 2090 may include an indentation 2794 on a short end edge region 2798 of ground plane 2090 suitable for allowing passage of cabling from modem 290 to PCBA 255 and / or 250. This passage of cabling from modem 290 to PCBA 255 and / or 250 may interconnect with modem port 535. Accordingly, modem port 535 may be located on a side of component mounting structure 2230 as indentation 2794 on the short edge region of ground plane.

[0352] Ground plane 2090 may also include one or more apertures 2797 and / or one or more apertures 2796 for fastening satellite modem 290 to ground plane 2090. As shown in Figure 27, ground plane 2090 may include eight apertures 2797. As shown in Figure 27, ground plane 2090 may include four apertures 2796.

[0353] As shown in Figures 27 and 28, ground plane 2090 may include an aperture 2780 for fastening antenna 580 to ground plane.

[0354] Furthermore, as shown in Figure 27, ground plane 2090 may include one or more apertures 2791 for securing ground plane 2090 to component mounting structure 2230 and mounting portions 2510 of upper part 2223 via fasteners, such as fasteners 2610.

[0355] The maximum width of ground plane 2090 may be between about 110 to 140 mm, 130 to 150 mm, or 135 to 160 mm. In some embodiments, the maximum width of ground plane 2090 is between about 120 to 125 mm, 125 to 130 mm, 130 to 135 mm, 135 to 140 mm, 140 to 145 mm, or 145 to 150 mm. In some embodiments, the maximum width of ground plane 2090 is about 120, 125, 130, 135, 140, 145, 150, or 155 mm. In some embodiments, the maximum width of ground plane 2090 is about 138 mm.

[0356] The maximum length of ground plane 2090 may be between about 130 to 170 mm, 150 to 180 mm, or 160 to 200 mm. In some embodiments, the maximum length of ground plane 2090 is between about 140 to 145 mm, 145 to 150 mm, 150 to 155 mm, 155 to 160 mm, 160 to 165 mm, or 165 to 170 mm. In some embodiments, the maximum length of ground plane 2090 is about 140, 145, 150, 155, 160, 165, 170, or 175 mm. In some embodiments, the maximum length of ground plane 2090 is about 163 mm.

[0357] The thickness of ground plane 2090 may be between about 1.5 mm to 8 mm, 2 to 20 mm, or 10 to 30 mm. The thickness of ground plane 2090 may be between about 2 to 3 mm, 2 to 4 mm, 4 to 6 mm, 6 to 8 mm, 8 to 10 mm, 10 to 12 mm, 12 to 15 mm,15 to 20 mm, or 20 to 25 mm. In some embodiments, the thickness of ground plane 2090 is about 2, 4, 6, 8, 10, 12, 15, 20, or 25 mm. In some embodiments, the thickness of ground plane 2090 is about 2 mm or 3 mm. The thickness, length and width of ground plane 2090 is selected to be structurally suitable for bearing modem 290 (and optionally for mounting antenna 580), while not having more material (mass) than is necessary.

[0358] Figure 30 shows an overhead view of lower part 2226 of data acquisition unit 2110, according to some embodiments. Figure 31 shows a cross-sectional view of lower part 2226 of data acquisition unit 2110, according to some embodiments. Figure 31 shows a second sub-assembly 2806. In some embodiments, the second sub-assembly 2806 may include lower part 2226 including transducer holding structure 3926, and vibration transducer 260. Second sub-assembly may include a flattened base 2228 and ribs 3060. The second sub-assembly 2806 may be described as a lower sub-assembly or seismic sensor integration sub-assembly.

[0359] The lower part 2226 of the housing 2220 includes transducer holding structure 3926 that protrudes into the central chamber. Transducer holding structure 3926 may be referred to as protruding structure 3926. The transducer holding structure 3926 may include a recess into the lower part 2226. The recess of transducer holding structure 3926 may be configured to hold the vibration transducer 260.

[0360] As shown in Figure 30, the transducer holding structure 3926 may include a plurality of internal ribs 3026 configured to be compressed by insertion of the vibration transducer 260 so that the protruding structure 3926 can securely hold the vibration transducer 260. The internal ribs 3026 may also allow the secure holding of vibration transducer 260 of different dimensions. It can be seen in Figure 30, the transducer holding structure 3926 may include four internal ribs 3026. In some embodiments, transducer holding structure 3926 includes one, two, three, four, five, six, seven, eight, nine, or ten internal ribs 3026, for example. The internal ribs 3026 may be equally spaced from one another.

[0361] The transducer holding structure 3926 may be supported by a plurality of radially projecting gussets or ribs 3060 extending from a central portion along respective internal bottom surfaces of internal floor 3045 of the lower part 2226 towards circumferential wall 3040 of the lower part 2226. Circumferential wall 3040 may also be referred to as outer wall 3040. As shown in Figure 30, lower part 2226 may include six gussets or ribs 3060. The gussets or ribs 3060 may be shaped as a trapezoid with two parallel sides one of which extending along the bottom surface, and two non-parallel sides, a third side at substantially right angle to the parallel sides and connected to the transducer holding structure 3926, and wherein the side along the bottom surface is shorter than its parallel counterpart side i.e. a right trapezoid.

[0362] Lower part 2226 may include a plurality of fastening portions 3030. Fastening portions 3030 may be referred to as fastening bosses 3030 or housing bosses 3030. As shown in Figure 30, lower part 2226 may include six fastening portions 3030. Fastening portions 3030 may be configured for fastening upper part 2223 to lower part 2226. Fastening portion 3030 may comprise structure and a recess within for receiving a fastener for attaching lower part 2226 to upper part 2223. The recess of fastening boss 3030 may be threaded. As shown in Figure 30, each fastening boss 3030 may be located proximate to a respective vertical edge or vertices of lower part 2226. Accordingly, mounting boss 2520 may be located on an opposite side of a concave indentation 2526 of lower part 2226. In some embodiments, the recess of fastening portion 3030 may extend from an underside surface of lower part 2226 through a surface of the concave indentation 2526, so that the respective fastener may be inserted from the recess in concave indentation 2526 through the fastening portion 3030 of lower part 2226 through to upper part 2223.

[0363] The structure of fastening portion 3030 may be tubular shaped. The structure of fastening portion 3030 may be surrounded by an inner wall structure 3526 and an outer wall structure 3527 of lower part 2226. The surrounding inner wall structure 3526 and outer wall structure 3527 may form an “eye” shape around the structure of fastening portion 3030. Outer wall structure 3527 may be a portion of walls 3040 of lower part 2226. Lower part 2226 and outer walls 3040 may have a convex polygonshaped cross-section, such as a hexagon, with inner walls and fastening portion bounded within. Inner wall structure 3526 may be a protruding structure from walls 3040. Fastening portion 3030 may be connected to the outer wall structure 3527 and / or inner wall structure 3526 by respective ribs 3031.

[0364] As shown in Figure 30, lower part 2226 may also include an o-ring seal groove 3050 on an upper facing portion of the circumferential wall 3040. O-ring seal groove 3050 may receive o-ring seal 2022. As shown in Figure 30, the o-ring seal groove 3050 may be located upon wall 3040 and pass through an internal facing portion of each inner wall structure 3526. This may mitigate any ingress from the recess of concave indentation 2523, mounting boss 2520, and fastening boss 3030. O- ring seal groove 3050 may therefore form a hexagonal shape with concave indentation at its vertices.

[0365] Figure 32 shows a perspective cross-sectional view of data acquisition unit 2110, according to some embodiments.

[0366] Figure 32 shows component mounting structure 2230 mounting ground plane 2090 together included within the housing 2220 formed by upper part 2223 and lower part 2226 of data acquisition unit 2110. As shown in Figure 32, vertical axis 305 (not a component of data acquisition unit 2110) extends through a central location of lower part 2226 and generally coincides with a longitudinal (long) axis of the data acquisition unit 2110. The upper part 2223 and lower part 2226 may have respective connection regions 3220 whereby the respective parts connect to each other. The connection region 3220 may include a seam 3222 between the upper part 2223 and lower part 2226. Ground plane 2090 may be horizontally oriented attached on top of component mounting structure 2230. Ground plane 2090 may extend a substantial cross-sectional area within central chamber of closed housing 2220. The edges of ground plane 2090 may be proximate and / or in contact with at least one inner wall portion of housing 2220.

[0367] When the data acquisition unit 2110 is assembled, the ground plane 2090 divides the central chamber into an upper space 3091 and a lower space 3092. Upper space 3091 and lower space 3092 are volumes in central chamber of housing 2220. The respective volumes of upper space 3091 and lower space 2092 may be unequal. Upper space 3091 and lower space 3092 may have different components within. Upper space 3091 may include satellite modem 290. Lower space 3092 may include component mounting structure 2230, PCBA 250, PCBA 255, shielding structure 2450, transducer holding structure 3926, and / or vibration transducer 260.

[0368] Similarly to data acquisition unit 110 as depicted on Figure 13 and as discussed with respect to Figure 21, data acquisition unit 2110 may be designed so that the upper part 2223 and / or the lowermost peripheral on upper part 223 is confined to an upper portion of the housing 2220, so that the majority of the structure of housing 2220 can be buried in the soil whilst the peripherals remain above the soil. Furthermore, data acquisition unit 2110 may be designed so that the position of the satellite modem 290, the ground plane 2090, and / or the upper surface of the component mounting structure 2230 has a vertical location in horizontal alignment or approximate alignment to: a vertical location of the connecting regions 3220 of upper part 2223 and lower part 2226 and / or a vertical location of the lowermost located peripheral on upper part 2223. This vertical location alignment may allow data acquisition unit 2110 to be suitably buried so that the surface of the soil surrounding the housing 2220 functions at least somewhat as a further (or extended) reflecting ground plane for enhancing the radio communications of the satellite modem 290 inside the housing 2220. The (approximate) horizontal alignment may be in reference to an alignment on a frame of reference axis perpendicular to vertical axis 305.

[0369] As shown in Figure 32, the modem 290 is mounted on ground plane 2090 within the housing 2220. In some embodiments, modem 290 may be in contact with upper part 2223. In some other embodiments, modem 290 may be spaced from upper part 2223.

[0370] As shown in Figure 32, the component mounting structure 2230 may mount PCBA 255 and the shielding structure 2450 shields the PCBA 250 housed within. Also, as shown in Figure 32, the transducer holding structure 3926 holds transducer 260 within housing 2220. The two opposite outer side faces of component mounting structure 2230 bearing PCBAs 255 and 250 may extend to a vertical position that is below a vertical position of a (horizontally extending) central underside portion 3230 of the component mounting structure 2230. Accordingly, when assembled, the central underside portion 3230 and vertically extending portions of the outer side faces of component mounting structure 2230 form a cavity for covering the protruding structure. In some additional or alternative embodiments, PCBA 250 and / or 255 may extend to a vertical position that is below the vertical position of the central underside portion 3230 of the component mounting structure 2230. Accordingly, when assembled, the central underside portion 3230 and vertically extending portions of the PCBA 250 and / or 255 (and optionally outer side faces of component mounting structure 2230) form a cavity for covering the protruding structure. This may allow efficient use of chamber space within housing 2220. For example, it may allow retaining or increasing PCBA 250, PCBA 255, modem 290, vibration transducer 260, and / or power source 2240 height dimensions whilst narrowing height of housing 2220.

[0371] In some embodiments, the component mounting structure 2230 and PCBAs 250 and 255 are not attached or in contact with lower part 2226 when assembled. In some other embodiments, the component mounting structure 2230, shielding structure 2450, and / or PCBAs 250 and 255 are attached or in contact with lower part 2226 when assembled. In some embodiments, data acquisition unit 2110 includes component mounting platform 830 on transducer holding structure 3926. In some embodiments, component mounting structure 2230, shielding structure 2450, and / or PCBAs 250 and 255 may attach or contact transducer holding structure 3926, component mounting platform 830, ribs 3060, or one or more portions of lower part 2226. The topology and mechanical arrangement of components of data acquisition unit 2110 is configured to promote effective measurement performance of the vibration transducer 260.

[0372] Handle 2521, user input 274, debugging port 276, and level indicator 270 are also shown to be mounted on the top surface of upper part 2223. In some embodiments, the base 2228 of lower part 2226 is not thickened as shown in Figure 32. In some embodiments, the base 2228 of lower part 2226 may be thickened or weighted.

[0373] In some embodiments, reference to vertical or horizontal may be with respect to an intended operational orientation of data acquisition units 110 or 2110 in which vertical axis 305 extends generally vertically (and the upper part of the housing 2220 is located above the lower part). Reference to vertical may be parallel or substantially parallel with vertical axis 305. Reference to horizontal may be perpendicular or substantially perpendicular with vertical axis 305.

[0374] It will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. A data acquisition unit for performing passive seismic monitoring, the data acquisition unit including: a housing including an upper part and a lower part, the lower part including a vibration sensing portion for sensing vibration in a ground region, and the upper part and lower part together defining a central chamber; a vibration transducer configured to receive vibrations via the vibration sensing portion and generate an output signal based on the received vibrations; a processing unit configured to receive and process the output signal to generate one or more data pay loads; a synchronisation unit including an antenna, wherein the synchronisation unit is configured to receive a synchronisation signal from a satellite via the antenna and to communicate synchronisation data to the processing unit based on the synchronisation signal; a power source to provide power to the processing unit and synchronisation unit; a component mounting structure received in the chamber and coupled to the housing, the processing unit and the synchronisation unit are coupled to and carried by the component mounting structure, the power source coupled to and received by the component mounting structure; and a satellite modem disposed at a top portion of the housing, wherein the satellite modem is configured to receive one or more generated payloads from the processing unit and transmit the one or more generated payloads to a second satellite.

2. The data acquisition unit of claim 1, wherein the component mounting structure is attached to the upper part.

3. The data acquisition unit of claim 1 or claim 2, wherein the component mounting structure comprises outer side faces for mounting one or more printed circuit board (PCB) assemblies, the one or more PCBAs configured for bearing the processing unit and the synchronisation unit.

4. The data acquisition unit of claim 3, further including two PCBAs bearing the processing unit and the synchronisation unit, the two PCBAs mounted on opposite outer side faces of the component mounting structure.

5. The data acquisition unit of any one of claims 1 to 4, wherein the component mounting structure comprises multiple pieces.

6. The data acquisition unit of any one of claims 1 to 5, wherein the component mounting structure comprises a single u-shaped piece.

7. The data acquisition unit of any one of claims 1 to 6, wherein the component mounting structure is a unitary structure.

8. The data acquisition unit of any one of claims 5 to 7, wherein the component mounting structure has a lower compartment for carrying the power source.

9. The data acquisition unit of any one of claims 1 to 8, wherein the lower part includes a protruding structure into the central chamber, the protruding structure including a recess, the recess configured to hold the vibration transducer.

10. The data acquisition unit of claim 9, wherein one or more lower outer portions of the component mounting structure include extending flanges which contact and stabilise the component mounting structure to the lower part, and wherein the extending flanges space an inner lower portion of the component mounting structure from thelower part, so that the inner lower portion of the component mounting structure is above or in contact with the held vibration transducer and / or the protruding structure.

11. The data acquisition unit of any one of claims 1 to 10, further comprising one or more antenna mounts on the inside of the upper part for attaching the antenna in the central chamber.

12. The data acquisition unit of claim 11, wherein the antenna is a monopole antenna, and / or the one or more antenna mounts each comprises a ring to support the antenna.

13. The data acquisition unit of any one of claims 1 to 10, further comprising an antenna mount on the component mounting structure for attaching the antenna.

14. The data acquisition unit of claim 13, wherein the component mounting structure comprises a top compartment, and the antenna mount is configured for attaching the antenna within the top compartment.

15. The data acquisition unit of claim 14, wherein the upper part of the housing comprises a first modem port and the top compartment of the component mounting structure comprises a second modem port, so that the satellite modem can be communicatively coupled to the processing unit via a cable and the first and second modem ports.

16. The data acquisition unit of any one of claims 13 to 15, wherein the antenna is a monopole antenna.

17. The data acquisition unit of any one of claims 11 to 16, wherein the antenna mount is configured for attaching the antenna, perpendicular to a longitudinal axis of the data acquisition unit.

18. The data acquisition unit of any one of claims 1 to 17, wherein the satellite modem includes a satellite communication antenna, the satellite modem is configuredto transmit the one or more generated payloads to the second satellite via the satellite communications antenna, optionally the satellite modem is self-contained within a second housing, optionally the second housing having an ingress protection (IP) rating of at least 67.

19. The data acquisition unit of any one of claims 1 to 18, wherein the satellite modem consumes about 9.6 to 9.8 Wh in a day, based on a transmission duty cycle of about 2% and reception duty cycle of about 12.5%.

20. The data acquisition unit of any one of claims 1 to 19, wherein the processing unit and / or the satellite modem is configured to transmit about 100 kilobytes to 450 kilobytes of one or more payloads per day to the second satellite.

21. The data acquisition unit of any one of claims 1 to 20, wherein the processing unit and / or satellite modem is configured to transmits the one or more payloads per day to the satellite modem on a randomised scheduled timing with an average transmission time interval (TTI) of about 10 to 30 seconds.

22. The data acquisition unit of any one of claims 1 to 21, wherein the upper part and lower part are formed using Polycarbonate (PC) and acrylonitrile butadiene styrene (ABS).

23. The data acquisition unit of any one of claims 1 to 22, wherein the power source has a mass between about 500 grams to about 1200 grams and the data acquisition unit has a mass between about 2190 grams to about 3375 grams.

24. The data acquisition unit of any one of claims 1 to 23, wherein the vibration sensing portion is formed using Polycarbonate (PC) and acrylonitrile butadiene styrene (ABS).

25. The data acquisition unit of any one of claims 1 to 24, wherein the vibration sensing portion is integrally formed with the lower part.

26. The data acquisition unit of any one of claims 1 to 25, wherein the upper part is between about 140 mm to 250 mm in diameter.

27. The data acquisition unit of any one of claims 1 to 26, wherein the lower part is between about 140 mm to 250 mm in diameter.

28. The data acquisition unit of any one of claims 1 to 27, wherein the power source has dimensions between about 72 mm to 80 mm in width, 68 mm to 76 mm in length, and 110 to 118 mm in height.

29. The data acquisition unit of any one of claims 1 to 28, wherein the component mounting structure has dimensions between about 68 to 90 mm in width, 68 mm to 90 mm in length, and 110 mm to 150mm in height.

30. The data acquisition unit of any one of claims 1 to 29, wherein the power source has an energy storage capacity between about 85 Wh and 285 Wh or between about 85 Wh and about 350 Wh.

31. The data acquisition unit of claim 30, wherein the power source has an energy storage capacity between about 240 Wh and 285 Wh or between about 240 Wh and about 350 Wh.

32. The data acquisition unit of claim 31, wherein the power source is a 24-cell battery.

33. The data acquisition unit of any one of claims 1 to 32, wherein the satellite modem is at least one of: encased in the housing; or attached to a mounting portion of the upper part.

34. The data acquisition unit of claim, 33, wherein the upper part mounting portion defines a recess to receive the satellite modem therein.

35. A method of data acquisition performed by a data acquisition system, the data acquisition system including multiple ones of the data acquisition units according to any one of claims 1 to 34, the method comprising: positioning the multiple data acquisition units at spaced surface locations across a ground region; and operating each of the data acquisition units to receive vibrations over a plurality of days; wherein the data acquisition units are operable to generate and send processed data based on vibrations received by the data acquisition units at the spaced surface locations.

36. The method of data acquisition of claim 35, wherein the operating includes continuous operation of the one or more data acquisition units to receive vibrations and generate the processed data.

37. The method of data acquisition of claim 35 or claim 36, wherein the operating includes continuous operation of the one or more data acquisition units to receive vibrations and generate the processed data for a period of between 4 and 10 days, wherein a power supply or power source of each of the one or more data acquisition units is contained within the housing of each of the one or more data acquisition units and is configured to supply power for operation of the respective data acquisition unit for more than 10 days.

38. The method of data acquisition of any one of claims 35 to 37, wherein the data acquisition system includes one or more satellites, one or more ground stations, and a server system, and wherein the one or more data acquisition units are operable to generate and send the processed data, via the one or more satellites and one or moreground stations, to a server system for performing computed tomography of the subsurface of the ground region.

39. A data acquisition unit for performing passive seismic monitoring, the data acquisition unit including: a first housing defining a central chamber; a vibration transducer in the housing, the vibration transducer configured to receive vibrations via the housing and generate an output signal based on the received vibrations; a processing unit configured to receive and process the output signal to generate one or more data pay loads; a synchronisation unit including an antenna, wherein the synchronisation unit is configured to receive a synchronisation signal from a first satellite via the antenna and to communicate synchronisation data to the processing unit based on the synchronisation signal; a power source to provide power to the processing unit and synchronisation unit; a satellite modem disposed inside the first housing, wherein the satellite modem is configured to receive one or more generated payloads from the processing unit and transmit the one or more generated payloads to a second satellite.

40. The data acquisition unit of claim 39, wherein the first housing includes an upper part and a lower part, the upper part and lower part together defining the central chamber.

41. The data acquisition unit of claim 39 or claim 40, further including:a component mounting structure received in the central chamber and coupled to the first housing.

42. The data acquisition unit of claim 41, wherein the component mounting structure comprises a second housing with an internal chamber, the second housing receiving the power source in the internal chamber.

43. The data acquisition unit of claim 41 or claim 42 when dependent on at least claim 40, wherein the component mounting structure is attached to the upper part of the first housing.

44. The data acquisition unit of any one of claims 41 to 43 when dependent on at least claim 40, wherein the lower part of the first housing includes a protruding structure that protrudes into the central chamber, the protruding structure including a recess into the lower part, the recess configured to hold the vibration transducer.

45. The data acquisition unit of claim 44, wherein the protruding structure includes a plurality of internal ribs configured to be compressed by insertion of the vibration transducer into the recess so that the protruding structure can securely hold the vibration transducer.

46. The data acquisition unit of any one of claims 41 to 45, wherein the processing unit and the synchronisation unit are coupled to and carried by the component mounting structure.

47. The data acquisition unit of any one of claims 41 to 46, wherein the component mounting structure comprises outer side faces for mounting one or more printed circuit board assemblies (PCBAs), the one or more PCBAs configured for including the processing unit and the synchronisation unit.

48. The data acquisition unit of claim 44 or claim 45, further including two printed circuit board assemblies (PCBAs) wherein at least one PCBA of the two PCBAs isconfigured to include the processing unit and the synchronisation unit, the two PCBAs mounted on two opposite outer side faces of the component mounting structure.

49. The data acquisition unit of any one of claims 39 to 46, wherein a first printed circuit board assembly (PCBA) is disposed inside the housing and includes the processing unit and the synchronisation unit.

50. The data acquisition unit of claim 49, further including an electromagnetic shielding structure enclosing the first PCBA.

51. The data acquisition unit of claim 48, wherein a first vertical position of the two opposite outer side faces extend below a second vertical position of a central underside portion of the second housing so that, when assembled, the second housing forms a cavity for covering the protruding structure.

52. The data acquisition unit of claim 48 or 51, wherein a first vertical position of the two PCBAs extend below a second vertical position of a central underside portion of the second housing.

53. The data acquisition unit of any one of claims 39 to 52, further including a ground plane, wherein the satellite modem is coupled to the ground plane.

54. The data acquisition unit of claim 53, wherein the satellite modem is mounted to the ground plane.

55. The data acquisition unit of claim 53 when dependent on any one of claims 41 to 52, wherein the ground plane is coupled to the component mounting structure.

56. The data acquisition unit of claim 53 or claim 54, wherein the ground plane includes indentations along one or more edges of the ground plane to permit passage of cabling from a first space above the ground plane to a second space below the ground plane.

57. The data acquisition unit of any one of claims 53 to 55, wherein the antenna is mounted to the ground plane.

58. The data acquisition unit of claim 40 or any one of claims 41 to 56 when dependent on claim 40, wherein the lower part is free of a vibration sensing projection or spike extending from the housing.

59. The data acquisition unit of claim 40 or any one of claims 41 to 57 when dependent on claim 40, wherein the lower part includes a plurality of radially projecting ribs on an internal floor of the lower part.

60. A data acquisition unit for performing passive seismic monitoring, the data acquisition unit including: a first housing defining a central chamber; a vibration transducer in the housing, the vibration transducer configured to receive vibrations via the housing and generate an output signal based on the received vibrations; a processing unit configured to receive and process the output signal to generate one or more data pay loads; a synchronisation unit including an antenna, wherein the synchronisation unit is configured to receive a synchronisation signal from a satellite via the antenna and to communicate synchronisation data to the processing unit based on the synchronisation signal; a power source to provide power to the processing unit and synchronisation unit; and a ground plane for mounting a satellite modem, the ground plane received in the central chamber.

61. A data acquisition unit for performing passive seismic monitoring, the data acquisition unit including: a first housing defining a central chamber; a vibration transducer in the housing, the vibration transducer configured to receive vibrations via the housing and generate an output signal based on the received vibrations; a processing unit configured to receive and process the output signal to generate one or more data pay loads; a synchronisation unit including an antenna, wherein the synchronisation unit is configured to receive a synchronisation signal from a satellite via the antenna and to communicate synchronisation data to the processing unit based on the synchronisation signal; a power source to provide power to the processing unit and synchronisation unit; and a component mounting structure for mounting a satellite modem, the component mounting structure received in the central chamber and coupled to the first housing.

62. The data acquisition unit of claim 60 or claim 61, wherein the first housing includes an upper part and a lower part, the upper part and lower part together defining the central chamber.

63. The data acquisition unit of claim 60 or claim 62 when dependent on claim 60, further including: a component mounting structure received in the central chamber and coupled to the first housing.

64. The data acquisition unit of claim 61 or claim 63, wherein the component mounting structure comprises a second housing with an internal chamber, the second housing receiving the power source in the internal chamber.

65. The data acquisition unit of claims 63 or 64 when dependent on claim 62, wherein the component mounting structure is attached to the upper part of the first housing.

66. The data acquisition unit of claim 62 or any one of claims 63 to 65 when dependent on claim 62, wherein the lower part of the first housing includes a protruding structure that protrudes into the central chamber, the protruding structure including a recess into the lower part, the recess configured to hold the vibration transducer.

67. The data acquisition unit of claim 66, wherein the protruding structure includes a plurality of internal ribs configured to be compressed by insertion of the vibration transducer into the recess so that the protruding structure can securely hold the vibration transducer.

68. The data acquisition unit of any one of claims 63 to 65, wherein the processing unit and the synchronisation unit are coupled to and carried by the component mounting structure.

69. The data acquisition unit of any one of claims 63 to 65 or claim 69, wherein the component mounting structure comprises outer side faces for mounting one or more printed circuit board assemblies (PCBAs), the one or more PCBAs configured for including the processing unit and the synchronisation unit.

70. The data acquisition unit of any one of claims 60 to 69, wherein a first PCBA includes the processing unit and the synchronisation unit.

71. The data acquisition unit of claim 70, further including an electromagnetic shielding structure enclosing the first PCBA.I l l72. The data acquisition unit of claim 61 or any one of claims 62 to 71 when dependent on claim 61, further including a ground plane, wherein the satellite modem is coupled to the ground plane.

73. The data acquisition unit of claim 60 or claim 72, wherein the ground plane separates a first space above the ground plane containing the satellite modem and a second space below the ground plane containing the processor and synchronisation unit.

74. The data acquisition unit of claim 72 or claim 73, wherein the ground plane substantially extends a horizontal cross-section of the internal chamber of the first housing.

75. The data acquisition unit of any one of claims 72 to 74 when dependent on any one of claims 65 to 69, wherein the ground plane is coupled to the component mounting structure.

76. The data acquisition unit of any one of claims 72 to 75, wherein the ground plane includes indentations along one or more edges of the ground plane to permit passage of cabling from the first space to the second space.

77. The data acquisition unit of any one of claims 72 to 76, wherein the ground plane is located at a vertical location in the central chamber in horizontal alignment or approximate alignment to: a vertical location of connecting regions of the upper part and the lower part and / or a vertical location of a lowermost located peripheral component of the upper part.

78. The steps, features, assemblies, sub-assemblies, components and / or integers disclosed herein or indicated in the specification of this application individually or collectively, and any and all combinations of two or more of said steps, features, assemblies, sub-assemblies, components and / or integers.

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