Wirelessly controlled transceiver acoustic modem

Abstract

A wirelessly controlled transceiver acoustic modem for a distributed fiber optic sensing (DFOS) system, comprising a circuit that receives a wireless signal containing configuration information, configures the modem to operate according to the configuration information, and generates an acoustic signal detected by the DFOS system. The acoustic modem further includes one or more sensors for detecting environmental information encoded in the acoustic signal for reception in the DFOS system. Depending on the received configuration information, the operating time of the modem, the sensors, or other operating modes are changed as needed, and that information is transmitted from a fixed location or a moving vehicle.

Description

Technical Field

[0001] This application generally relates to distributed fiber optic sensing (DFOS) systems, methods, structures, and related technologies. More specifically, it relates to a wirelessly controlled transceiver acoustic modem used to transmit vibration signals to an optical sensor fiber.

Background Art

[0002] Distributed fiber optic sensing (DFOS) technologies such as distributed acoustic sensing (DAS), distributed vibration sensing (DVS), and distributed temperature sensing (DTS) are well-established as being most useful for sensing acoustic events, vibration events, and temperature in a variety of modern applications. Considering such importance, improvements to DFOS technology or complementary systems would be a welcome plus for this technology.

Summary of the Invention

[0003] Aspects of the present disclosure relate to a wirelessly controlled transceiver acoustic modem for use in a distributed fiber optic sensing (DFOS) system and method, which bring progress in this technology.

[0004] In contrast to the prior art, from a first perspective, the wirelessly controlled acoustic modem of the present invention advantageously receives a wireless signal used to change the operating settings of the acoustic modem. This enables remote control of the acoustic modem and adjustment of its operating characteristics. The transceiver acoustic modem may include one or more sensors that generate acoustically encodable environmental information and acoustically excite a nearby sensing fiber for detection / analysis by the DFOS system.

[0005] In contrast to the prior art and from another perspective, the acoustic modem of the present invention adopts a novel method of acoustic modem communication via a DFOS / DAS system that advantageously improves the data transfer rate from the field to a central office or other locations where a DFOS / DAS interrogator is installed. Operationally, the acoustic modem of the present invention communicates by spatially multiplexing acoustic vibration codes. Instead of using only a single oscillator (or shaker or speaker), the spatial multiplexing acoustic modem of the present invention uses multiple oscillators placed at various locations along the sensing fiber. As long as the spacing between the multiple oscillators is greater than the resolution of the DFOS / DAS system, the DFOS / DAS system can simultaneously detect the signals of the multiple oscillators. As a result, when using n oscillators, the data transfer rate can be increased by n times.

[0006] Finally, in contrast to the prior art and from another perspective, the acoustic modem of the present invention wirelessly taps into a high-voltage power line to charge itself and supply power to sensors and oscillators for the transmission of acoustic data. As a result, the acoustic modem of the present invention can self-charge and transmit integrated sensor data through an OPGW (optical ground wire) cable via vibration.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0019] The following merely illustrates the principles of the present disclosure. Therefore, it should be understood by those skilled in the art that various configurations embodying the principles of the present disclosure, even if not explicitly described or illustrated herein, can be conceived within the spirit and scope of the present disclosure.

[0020] Furthermore, all examples and conditional terms recited herein are for the sole educational purpose of assisting the understanding of the concepts provided by the inventors to facilitate the principles of the present disclosure and this technology, and should not be construed as being limited to the specifically recited examples and conditions.

[0021] Furthermore, all descriptions in this specification of the principles, aspects and embodiments of the present disclosure, as well as all specific examples recited therein, are meant to include both their structural and functional equivalents. Furthermore, such equivalents are meant to include both currently known equivalents and equivalents developed in the future, i.e., elements developed that perform the same function regardless of their structure.

[0022] Thus, for example, it will be understood by those skilled in the art that any block diagram in this specification is a conceptual diagram specifically showing a circuit for implementing the principles of the present disclosure.

[0023] In this specification, unless otherwise specified, the drawings including the figures are not drawn to an exact scale.

[0024] As additional background, note that a distributed fiber optic sensing system interconnects optoelectronic integrators to an optical fiber (or cable) and converts the optical fiber into an array of sensors distributed along the fiber. In practice, the fiber becomes the sensor, and the interrogator generates / injects laser light energy into the fiber and senses / detects events along the fiber.

[0025] As will be understood and recognized by those skilled in the art, DFOS technology can be utilized to continuously monitor vehicle movement, human traffic, excavation work, seismic activity, temperature, structural integrity, liquid and gas leaks, and many other conditions and activities. It is used worldwide to monitor power plants, communication networks, railways, roads, bridges, borders, critical infrastructure, onshore and offshore power and pipelines, and downhole applications in oil, gas, and enhanced geothermal power generation. Distributed fiber optic sensing has the advantage that it is not subject to line-of-site or remote power access constraints and can be deployed in continuous lengths exceeding 30 miles while sensing / detecting at any point along its end-to-end length depending on the system configuration. As a result, the cost per sensing point over long distances is far below that of competing general technologies.

[0026] Distributed fiber optic sensing measures changes in the "backscattering" of light that occur within an optical sensing fiber when the sensing fiber encounters environmental changes such as events of vibration, strain, or temperature change. As described above, the sensing fiber functions as a sensor over its entire length and provides real-time information regarding the physical / environmental surroundings and the integrity / security of the fiber. Further, distributed fiber optic sensing data identifies the exact location of events and conditions occurring at or near the sensing fiber.

[0027] A schematic diagram showing the general arrangement and operation of a distributed optical fiber sensing system that advantageously includes artificial intelligence / machine learning (AI / ML) analysis is illustrated in FIG. 1(A). Referring to FIG. 1(A), it is observed that an optical sensing fiber is connected to an interrogator. Although not shown in detail, the interrogator may include an encoded DFOS system that can employ a configuration of a coherent receiver known in the art as shown in FIG. 1(B).

[0028] As is well known, a modern interrogator is a system that generates an input signal for an optical sensing fiber and detects / analyzes the reflected / scattered signal received. The received signal is analyzed to generate an output indicating the environmental conditions that occurred along the fiber. The received scattered signal is caused by reflections within the fiber such as Raman scattering, Rayleigh scattering, and Brillouin scattering.

[0029] As is understood, modern DFOS systems include an interrogator that periodically generates optical pulses (or any encoded signal) and inputs it into the optical fiber. The input optical pulse signal is transmitted along the optical fiber.

[0030] At positions along the fiber, a small portion of the signal is scattered / reflected and returned to the interrogator for reception. The scattered / reflected signal conveys information that the interrogator can use for detection, such as a change in power level indicating mechanical vibration.

[0031] The received scattered signal is converted to the electrical domain and processed by the interrogator. Based on the input time of the pulse and the time the signal is detected, the interrogator can determine from which position along the optical sensing fiber the received signal originated and sense the activities at each position along the optical sensing fiber. The method of classification may be further used to detect and identify events or other environmental conditions including acoustic and / or vibration and / or heat along the optical sensing fiber.

[0032] Figure 2 is a schematic diagram showing an exemplary DFOS operation, including an acoustic modem disposed on a utility pole that suspends an optical fiber sensor cable, which is a component of the DFOS system. As shown in this figure, the acoustic modem generates an acoustic signal, which excites the optical fiber sensor cable to generate vibrations, and the vibrations are detected / interpreted by the operation of the DFOS / DAS system. As described above, the acoustic modem supports wirelessly controlled transceivable communication, receives the transmitted, compliant wireless signal, and responds.

[0033] In the exemplary scenario shown in the figure, the vehicle is equipped with a wireless transmitter that emits radio waves to communicate with the acoustic modem and change the settings of the acoustic modem. For example, depending on the actual distance between the central office and the acoustic modem, the transmitter may be placed at the central office (or other fixed location), or at a mobile station such as the vehicle shown in the figure.

[0034] As can be easily understood by those skilled in the art, the wirelessly controlled acoustic modem of the present invention provides, for example, a snow accumulation measurement function that can be disabled in summer and turned on again in winter. Alternatively, the transmission period of the acoustic modem may be changed according to the operator's requirements.

[0035] As shown in the figure, the wireless signal transmitted to the acoustic modem may be from a fixed station or from a vehicle in motion or at rest. In a preferred embodiment, the wireless signal may be in an unlicensed radio frequency band and may use a known protocol.

[0036] In a preferred embodiment, the wirelessly controlled acoustic modem of the present invention employs transceivable communication via two different media.

[0037] The first type of communication and medium uses acoustic vibrations that excite nearby optical fiber cables and can be detected by a DFOS / DAS system over a distance of at least 50 km. This medium (DFOS / DAS optical fiber sensor cable) is deployed from an acoustic modem to an interrogator installed in a central office.

[0038] The second type of communication and medium is one of the ISM (Industrial, Scientific and Medical) bands and uses wireless signals in an unlicensed frequency band. Although such a wireless band is unlicensed, it is not without limitations. The main limitation is that the transmission power level cannot be increased too much. That is, the distance between the wireless receiver (acoustic modem) and the transmitter (controller) needs to be approximately 100 meters or less. Depending on the distance between the acoustic modem and the central office, the transmitter can be installed in the central office or a mobile station such as a vehicle. Such an operation is schematically shown in FIG. 2.

[0039] In summary, the wirelessly controlled acoustic modem of the present invention provides two communication functions of the acoustic modem and a mobile transmitter that enables the control of acoustic modems throughout the city. While enabling the on / off switching of the acoustic modem, the measurement settings (sensitivity, accuracy, etc.) of the acoustic modem may be adjusted and changed as needed or desired according to sensing requirements and changes in environmental conditions.

[0040] FIG. 3 is a schematic block diagram showing exemplary components of an acoustic modem according to an aspect of the present disclosure. As shown in this figure, the acoustic modem includes an acoustic / vibration generator, a transceiver that can advantageously provide the multi-mode communication, and a controller / computer for adjusting the operation of the acoustic modem.

[0041] FIG. 4 is a schematic flowchart showing an operational workflow of DFOS / DAS and an exemplary wireless acoustic modem according to an aspect of the present disclosure. As shown in this figure, first, the acoustic modem is attached at a position in physical contact with a nearby optical fiber cable. Next, the acoustic modem measures specific physical parameters and transmits the results via vibration based on settings. The vibration is remotely detected by DFOS / DAS. To change the settings of the acoustic modem, the transmitter transmits radio waves including configuration / setting data to the acoustic modem from a fixed station or a mobile station. The controller of the acoustic modem receives this data and uses it to reconfigure the operating parameters. Finally, the settings and parameters of the acoustic modem are changed. Such changes may include switching the sensor on / off as necessary or desired.

[0042] FIG. 5 is a schematic diagram showing exemplary features of a DFOS / DAS system employing an exemplary wireless acoustic modem according to an aspect of the present disclosure. As schematically shown in this figure, the acoustic modem realizes both optical fiber communication and wireless communication (by acoustic / vibration operation). The acoustic communication provides a communication medium (an optical fiber sensor cable that is part of DFOS / DAS) that does not perform cutting / splicing / termination processing. Wireless communication enables remote control of the acoustic modem and enables wireless reconfiguration of the acoustic modem. Finally, since wireless communication including reconfiguration information can be provided from a movable or fixed position, the versatility in reconfiguration is greatly improved.

[0043] According to another aspect of the present disclosure and the acoustic modem of the present invention, the acoustic modem is further improved by providing a function of spatially multiplexing and transmitting acoustic vibration codes. Instead of using a single oscillator (or shaker or speaker), in the operation of the spatially multiplexed acoustic modem of the present invention, a plurality of oscillator sources arranged at different locations along the optical fiber sensor cable are used. As long as the plurality of oscillators are arranged at intervals greater than the resolution of the DFOS / DAS system, the DFOS / DAS operation can simultaneously detect / collect signals from those oscillators. That is, when using n oscillators, the data transfer rate can be increased by n times.

[0044] As will be understood and recognized by those skilled in the art, the spatially multiplexed operation of the present invention enables the detection function of the DFOS / DAS system because data can be collected from multiple points along the fiber cable. As a result, the spatially multiplexed acoustic modem of the present invention can transmit data from multiple points via multiple vibration sources.

[0045] As can be easily understood by those skilled in the art, the spatially multiplexed acoustic modem of the present invention provides unique operations in the data transmission and data reception operations of DFOS / DAS. Regarding data transmission, spatial multiplexing in the acoustic region is adopted (that is, different parts of the data are simultaneously transmitted at different points along the fiber via different oscillators). Regarding data reception, the DFOS / DAS system simultaneously receives / detects / decodes DFOS / DAS data from multiple points along the path of the optical fiber sensor cable. That is, the signals detected at different points are combined and analyzed as a single transmission.

[0046] FIG. 6 is a schematic diagram showing the configuration and operation of an exemplary spatial multiplexing acoustic modem according to an aspect of the present disclosure. As shown in this figure, a series of n oscillators are attached at different n locations along the path of the fiber optic cable sensor. The n oscillators are controlled by a single acoustic modem. The n oscillators operate simultaneously at different frequencies and are received / detected / analyzed simultaneously by a single DFOS / DAS interrogator.

[0047] FIG. 7 is a schematic diagram showing the overall operating principle of the spatial multiplexing acoustic modem according to an aspect of the present disclosure.

[0048] First, the acoustic modem and the n oscillators are installed in the field. The n oscillators need to be installed at different n locations so as to couple to a single point along the fiber, and those oscillators need to be separated by at least the spatial resolution of the DFOS / DAS system. The data to be transmitted is sensor data, time values, or other data. Before the data is transmitted, the acoustic modem divides the data into n pieces for each of the n oscillators. Next, the acoustic modem maps the bits to frequencies (i.e., 101 corresponds to f c ). Next, the acoustic modem determines n different frequency vibration patterns, and the oscillators realize these vibrations. When the vibrations are coupled to the fiber, those vibrations are detected by the DAS system, demultiplexed, and decoded. Thus, the complete data stream is recovered.

[0049] FIG. 8 is a schematic flow diagram showing an operational workflow of DFOS / DAS and an exemplary spatial multiplexing acoustic modem according to an aspect of the present disclosure. As shown, a spatial multiplexing acoustic modem with n oscillators according to an aspect of the present disclosure is installed in the field, and the n oscillators are arranged at different positions along an optical fiber sensor cable. The main board / processor of the acoustic modem divides the data and transmits it to each of the n oscillators. The n oscillators transmit a part of the data simultaneously from their respective different locations. DFOS / DAS detects all the DFOS / DAS signals from the n oscillators, demultiplexes them to obtain a single data stream, and analyzes the single stream to decode the data. Finally, the overall operation is repeated.

[0050] First, it is necessary to install the acoustic modem and n oscillators in the field, and the n oscillators are installed at n different locations so as to be coupled to a single point along the fiber. They are separated at least according to the spatial resolution of the DAS system. The data can be sensor data, time values or other data. Before the data is transmitted, the acoustic modem divides the data into n for the n oscillators. Next, the acoustic modem maps the bits to frequencies (i.e., 101 corresponds to f c ). Next, the acoustic modem determines n different frequency oscillation patterns, and the oscillators realize these oscillations. When the oscillations are coupled to the fiber, they are detected by the DAS system, demultiplexed and decoded. Thus, the complete data stream is recovered.

[0051] FIG. 9 is a schematic diagram showing exemplary features of a DFOS / DAS system employing an exemplary spatial multiplexing acoustic modem according to an aspect of the present disclosure.

[0052] Note that due to the required power of the acoustic modem, it may be substantially and widely limited in use because it needs to be installed in a place where power is available to operate over a long period without the intervention of technicians.

[0053] Therefore, in the present invention, in order to supply power to the acoustic modem, the acoustic modem is provided with a wireless power tapping function from a high-voltage line. Since such power supply requires being close to the high-power electric wire, the applications related to the monitoring of the high-power electric wire are optimized.

[0054] In operation, the acoustic of the present invention is an upgraded acoustic modem that wirelessly taps the high-power line, charges itself for long-term operation or continuous operation preparation, and supplies power to the sensor and the oscillator. Our approach uses a wireless energy harvester similar to wireless charging technology. As a result, the acoustic modem of the present invention self-charges and transmits the integrated sensor data via the OPGW (optical ground wire) cable through vibration.

[0055] Advantageously, since the acoustic modem of the present invention uses power tapping from the high-voltage line to supply power to the acoustic modem, operation near the high-voltage line is practical. Since the acoustic modem utilizes the detection function of the DFOS / DAS system, it can be detected by the DFOS / DAS interrogator system located several kilometers away by simply generating mechanical vibration near the OPGW (optical ground wire) cable.

[0056] FIG. 10 is a schematic diagram showing an exemplary operation of an acoustic modem of an exemplary environmental power generation method according to an aspect of the present disclosure. As can be seen from this figure, the acoustic modem of the present invention for obtaining electrical energy includes at least three main operation components. The first component is a main control device including a sensor and a rechargeable battery. The second component is a wireless power tapping antenna that is disposed near but not physically in contact with a high voltage cable. This component is responsible for wirelessly obtaining electrical energy and supplying it to the main control device. The third component is an acoustic modem, which includes a shaker / vibrator and is attached to or near an OPGW cable. Further, there is also a DFOS / DAS system including an interrogator that interrogates the OPGW cable and detects vibrations generated by the shaker / vibrator of the device.

[0057] One of the advantageous features of the acoustic modem of the present invention with an environmental power generation function is that it is a completely separated system with respect to power. The modem of the present invention does not require either an optical connection or a "hard" physical electrical connection. Nor is it necessary to receive any communication or control signals from the outside. This is a completely self - contained device that can perform self - charging and pre - programmed missions (such as measuring specific physical parameters (temperature, humidity, pressure, snow accumulation, etc.) and transmitting their values by vibration at predetermined time intervals), and is also plug - and - play.

[0058] FIG. 11 is a schematic flow diagram showing the workflow of the operation of a DFOS / DAS and an exemplary environmental power generation method acoustic modem according to an aspect of the present disclosure.

[0059] FIG. 12 is a schematic diagram showing exemplary features of a DFOS / DAS system employing an exemplary environmental power generation method acoustic modem according to an aspect of the present disclosure.

[0060] Here, the present disclosure has been shown using several specific examples, but those skilled in the art will recognize that the present teachings are not limited thereto. Therefore, the present disclosure should be limited only by the claims appended hereto.

Claims

**Claim 1** A wirelessly controlled transceiver acoustic modem for a distributed fiber optic sensing (DFOS) system, receiving a wireless signal containing configuration information of the acoustic modem, processing a configuration for establishing operating parameters of the acoustic modem, the circuit being configured to generate a physical vibration according to the operating parameters, the physical vibration being detected by the DFOS system, a wirelessly controlled transceiver acoustic modem. **Claim 2** Further comprising one or more sensors for measuring physical environmental parameters, the circuit being further configured to process the measured parameters and generate the physical vibration according to the measured parameters, the wirelessly controlled transceiver acoustic modem according to claim 1. **Claim 3** The wirelessly controlled transceiver acoustic modem according to claim 2, wherein the received configuration information includes enabling or disabling the sensor. **Claim 4** The wirelessly controlled transceiver acoustic modem according to claim 3, wherein the received wireless signal is transmitted from a fixed position. **Claim 5** The wirelessly controlled transceiver acoustic modem according to claim 3, wherein the received wireless signal is transmitted from a movable vehicle.

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