Devices, systems and methods

Abstract

A wireless device of a set of at least two wireless devices for forming respective nodes in a multihop through-the-earth (TTE) communication network, the wireless device including: a wireless TTE receiver (Rx); a wireless TTE transmitter (Tx); a stored selectable / predefined data slot allocation, which defines one or more data slots and how the slots are divided; and a stored selectable / predefined round timing, which defines one or more time windows for one or more rounds of communication, wherein the or each round uses the data slot allocation, wherein the round timing controls the wireless device to concurrently transmit within at least one of the time windows with at least one other wireless device in the set of wireless devices, thus forming a concurrently communicating plurality of the nodes when the network is operating.

Description

DEVICES, SYSTEMSAND METHODSRELATED APPLICATIONS

[0001] The present application is related to the following patent applications, the specifications of which are hereby incorporated by reference in their entireties: a. International Patent Application No. PCT / AU2006 / 000085, "Wireless detonator assemblies, and corresponding networks"; b. International Patent Application No. PCT / AU2013 / 001171, "Locating underground markers"; c. International Patent Application No. PCT / SG2015 / 050322, "A wireless initiation device"; d. International Patent Application No. PCT / SG2020 / 050370, "Commercial blasting systems"; e. International Patent Application No. PCT / SG2025 / 050084, "System, apparatus and / or process"; f. International Patent Application No. PCT / SG2023 / 050551, "System, apparatus and / or process"; g. International Patent Application No. PCT / SG2024 / 050394, "Commercial blasting systems and methods"; h. International Patent Application No. PCT / SG2022 / 050714, "System and method / process for commercial blasting"; i. International Patent Application No. PCT / SG2020 / 050371, "Deployment of quasi-planar shock wave generators in association with seismic exploration";j. International Patent Application No. PCT / SG2024 / 050396, "Signalling / communication system and method for devices"; k. International Patent Application No. PCT / SG2023 / 050678, "Electronic device", l. International Patent Application No. PCT / SG2022 / 050603, " Safety systems for commercial blasting operations"; and m. Australian Provisional Patent Application No. 202490 149, “Devices, Systems and Methods”.TECHNICAL FIELD

[0002] The present invention relates to devices, systems and methods for through-the-earth (TTE) wireless communication, including in any one or more of the following operations, e.g., relating to buryable or buried devices: (i) commercial blasting, including using initiation devices such as explosive primers that are configurable or configured for wireless communication, e.g., for mining and quarrying, seismic exploration, or avalanche blasting;(ii) monitoring movement or location (e g., position and / or orientation (P&O), and / or vibration) in portions of ground / earth (e.g., as ore markers) or structures (e.g., including buildings, civil engineering structures); (iii) sensing of properties of ground / earth or structures (e.g., sensing temperature, moisture content, etc.); and / or (iv) relaying network signals between communication nodes. In multiple embodiments, such operations may be part of or related to commercial blasting operations.BACKGROUND

[0003] Applications of commercial blasting are found in mining operations (both surface mining and underground mining), in quarrying operations, in seismic survey operations (on land and undersea), in avalanche blasting operations, and in civil engineering operations (e g., demolition and tunnelling).

[0004] Through-the-earth (TTE) wireless systems have recently been developed, e.g., by ORICA, that use magnetic induction (MI) to communicate through earth / rock / etc. to buried / in-ground / in-hole wireless devices (which can be buried and consumed in a blast) incommercial blasting applications, e.g., ORICA's WEBGEN technology. The term “TTE wireless” refers to communi cation / si nalling that travels through the earth (or rock / etc.) itself, which is substantially non-conductive, without there being any physical wires / cables present through that earth: a benefit is provision of communication / signalling without requiring placement of physical wires / cables along the communication / signalling pathway. Each buried / in-ground / in-hole wireless device can have internal wiring within the define to provide communication, however, any wireless communication from or to the wireless device, including TTE, occurs without being carried by conductors / wires / cables / etc., as is required for “wired communication”.

[0005] Existing TTE wireless systems used in commercial blasting applications tend to only provide high-quality one-way MI communication to the buried / in-ground wireless devices (e.g., to send SYNC or FIRE commands to buried / in-ground wireless initiator devices) from external control equipment, e.g., central controllers and blasting machines, that are typically not buried or damaged during blasting. For example, ORICA's WEBGEN blasting system only offers one-way communication from the Transmitter to the Disposable Receiver (DRX), which leads to a significant limitation, where it is not possible to check the status of the encoded DRX once it is loaded in a blasthole. Although uplink communication from an inhole primer to a MI receiver outside of the hole may be achievable, the range of this uplink communication is, however, typically quite limited or possibly severely constrained, e.g., to around 30 metres in favoured ground conditions, due to constraints in the physical size and cost of the primer, as well as its power budget; this uplink range limitation is a particular challenge for deep holes, where the buried primers would not be able to reach the out-of-hole receiver using a direct communication connection.

[0006] It is desirable in some applications to have high-quality two-way TTE communication between the buried / in-ground wireless devices and the external control equipment; however, using conventional approaches to avoid message collisions between signals from different nodes in the network do not scale well with network size, e.g., for networks larger than several hundred nodes, the overheads of managing the network became too large for it to function.

[0007] A proposal for a bidirectional wireless detonator system is described inUS20210318107A1 (to DETNET SOUTH AFRICA PTY LTD), however, this system may be undesirably slow, too power-hungry and / or too complicated for at least some applications, e.g., for large network sizes.

[0008] It is desired to address or alleviate one or more disadvantages or limitations of the prior art, or to at least provide a useful alternative.SUMMARY

[0009] One or more embodiments of the present invention include a wireless device of a set of at least two wireless devices for forming respective nodes in a multihop through-the-earth (TTE) communication network, the wireless device including: a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one (first) other wireless device in the set of wireless devices; a wireless transmitter (Tx) configured to transmit TTE signals representing an outgoing message to at least one (second) other wireless device in the set of wireless devices (that is different from the first other wireless device); a stored selectable / predefmed data slot allocation, which defines one or more data slots and how the slots are divided; and a stored selectable / predefmed round timing, which defines one or more time windows for one or more rounds of communication, wherein the or each round uses the data slot allocation, wherein the wireless device is configured to: interpret the incoming message based on the incoming message (or properties of the incoming message) compared to the selectable / predefmed data slot allocation, and transmit the outgoing message according to the selectable / predefmed data slot allocation and the selectable / predefmed round timing, andwherein the round timing controls the wireless device to concurrently transmit within at least one of the time windows with at least one other wireless device in the set of wireless devices, thus forming a concurrently communicating plurality of the nodes when the network is operating.

[0010] The data slot allocation may include only 1 data slot in each round, e g., to provide a data flood.

[0011] The data slot allocation may include 2 or more data slots in each round, e.g., to provide a plurality of substantially instantaneous data floods, e g., propagating in different directions in the network.

[0012] The wireless device may be configured to transmit the outgoing message in the same round as receiving the incoming message, e.g., if negligible processing time is required, which may be in the same slot or in a different slot.

[0013] The wireless device may be configured to transmit the outgoing message in a different round from when the incoming message is received, e.g., to account for processing delay and / or to keep the transmission start times of each round synchronised across the network.

[0014] The wireless device may be configured to transmit the outgoing message in a different slot from the one or more slots of the incoming message, e g., using a different slot if the outgoing message includes different information from the incoming message.

[0015] The wireless device may be configured to transmit the outgoing message in at least one of same slots as the one or more slots of the incoming message, optionally in the same slot, e.g., for a data flood.

[0016] The data slot allocation may include at least 2 bits in each data slot, or at least 3 bits in each data slot, or at least 4 bits in each data slot, e.g., defining a message header, error detection / correct! on, message data, data commands, etc.

[0017] The data slot allocation may include only 1 bit in each data slot, e.g., for a data flood or alert.

[0018] The data slots may include a plurality of mutually different time slots (thus providing time-divided concurrent data slots).

[0019] The data slots may include a plurality of mutually different frequency slots (thus providing frequency-divided concurrent data slots).]0020] The data slots may include a plurality of mutually different code slots (thus providing code-divided concurrent data slots).

[0021] The incoming message (or the properties of the incoming message) may include a type of the data slot, optionally a time slot, a frequency slot or a code slot.

[0022] The TTE signals may include magnetic induction (MI) signals, optionally including a carrier frequency of at least 1 kHz and no more than 200 kHz; and optionally of no more than 50 kHz, optionally of no more than 40 kHz, optionally of no more than 30 kHz, optionally of no more than 20 kHz, optionally of no more than 10 kHz, or optionally of no more than 5 kHz.]0023] The wireless device may be configured to synchronise its clock using timing of the incoming message, optionally for a blasting delay.|0024| The wireless device may be configured to generate the outgoing message by retransmitting the incoming message, thus enabling the data messages to flood across the network according to the stored selectable / predefmed round timing, e.g., to provide a data flood.

[0025] The wireless device may be configured to retransmit the incoming message substantially immediately after a zero or negligible delay, e.g., to provide a (substantially) instantaneous data flood.|0026| The wireless device may be configured to retransmit the incoming message after a defined delay, optionally wherein the defined delay includes: (a) a fixed delay; (b) an adaptive delay; and / or (c) a delay count, e.g., to account for processing delay and / or to keep the transmission start times of each round synchronised across the network, including during a data flood.

[0027] The wireless device may be configured to retransmit the incoming message when the incoming message is in a certain slot of the stored data slot allocation indicating that the incoming message is to be retransmitted as a flood message; and / or when a header of the incoming message indicates that the incoming message is to be retransmitted as a flood message.

[0028] The wireless device may be configured to generate outgoing messages in two or more of the data slots by retransmitting incoming messages received in two or more respective ones of the data slots, thus enabling two or more (mutually different) data messages to flood across the network simultaneously.

[0029] The wireless device may be configured to recognise a node identifier (ID) in the incoming message in order to decide whether to generate the outgoing message, e.g., to provide concurrent routing across the network.

[0030] The wireless device may be configured to generate the outgoing message based on any one or more of: a hop count determined from a hop court of the incoming message plus 1, e g., to have the number of hops across the network nodes automatically included in the outgoing message; the received TTE signals, optionally including a signal strength (e g., RSSI) of the received TTE signals, e g , to allow the wireless device to indicate attenuation etc. to the other nodes; stored data in the storage, optionally including a unique identifier (ID) of the wireless device in the set of wireless devices, e.g., to provide concurrent routing across the network, and / or to indicate a source of the outgoing message, e.g., if a measurement is made by the wireless device; and a timer of the wireless device, optionally a periodic timer.

[0031] The wireless device may be configured to generate the outgoing message based on at least one sensor measurement made by the wireless device, e.g., to measure the in-ground environment, optionally including generating the outgoing message when the sensormeasurement exceeds a predetermined threshold, e g., to avoid using stored electrical power to send unimportant measurements.

[0032] The sensor measurement may include any one or more of: a temperature measurement, a pressure measurement, a moisture measurement, a shock measurement, a pH measurement, a humidity measurement, an acceleration measurement, an orientation measurement, and a magnetic field measurement.

[0033] The wireless device may include a housing configured and formed to seal and protect the wireless device from water and impact when deployed in a mining / blasting environment. The housing may be at least partially transparent to the TTE signals, thus allowing the TTE signals to travel at least partially through the protective housing from and / or to one or more antennas of the transmitter Tx and / or receiver Rx components., e.g., such that the antenna may be referred to as “integrated” into the wireless device.

[0034] The wireless device may include at least one circuit-based processor, and machine- readable storage connected to the at least one circuit-based processor, wherein the machine- readable storage includes: the selectable / predefmed data slot allocation and the selectable / predefined round timing, and machine-readable instructions that control the at least one circuit-based processor to interpret the incoming message and transmit the outgoing message.

[0035] The stored selectable / predefmed data slot allocation and the stored selectable / predefmed round timing may be: hardcoded in the wireless device, e g., during manufacture, in a factory; encoded into the wireless device using an encoding machine, e.g., in a mining environment, on a mining bench, and / or underground; and / or received by the wireless device in a wireless message using a non-concurrent network protocol, e.g., a TTE wireless message after the wireless device is in situ, in the earth / rock, in a bore hole, etc.

[0036] One or more embodiments of the present invention include a multihop TTE communication system including: the wireless device above; and at least one edge device, e.g., not completely buried in the ground / earth / rock, that includes: at least one of: a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one other wireless device in the set of wireless devices, and a wireless transmitter (Tx) configured to transmit TTE signals representing an outgoing message to at least one other wireless device in the set of wireless devices; the selectable / predefined data slot allocation; and the selectable / predefined round timing, wherein the edge device includes at least one non-TTE communications device for non-TTE communication of the incoming message and / or the outgoing message to a control / monitoring system.

[0037] One or more embodiments of the present invention include a multihop TTE communication system including: the wireless device above; and at least one listen-only wireless device that includes: a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one other wireless device in the set of wireless devices; the selectable / predefined data slot allocation; andthe selectable / predefined round timing, wherein the listen-only wireless device is configured to interpret the incoming message based on the incoming message (or properties of the incoming message) compared to the selectable / predefined data slot allocation.|0038| One or more embodiments of the present invention include a multihop TTE communication system including: the wireless device above; and another of the wireless devices in the set arranged for TTE communication with the wireless device such that the wireless device is an intermediate node in the network.

[0039] One or more embodiments of the present invention include a method of operating the through-the-earth (TTE) communication network formed of the set of wireless devices above, the method including: a first one of the wireless devices generating TTE signals representing a first message; a second one of the wireless devices receiving the TTE signals representing the first message; the second one of the wireless devices transmitting TTE signals representing a second message based on the first message; and a third one of the wireless devices receiving the TTE signals representing the second message.

[0040] The method may include one or more of: wireless blasting of the wireless device, signal surveying by the wireless device, sensing by the wireless device, and / or localization of the wireless device, e.g., depending on the operation / application.

[0041] The first one of the wireless devices may be: an edge node of the network; or a deep node of the network.

[0042] One or more embodiments disclosed herein include a wireless device in a set of wireless devices configured for through-the-earth (TTE) communication, the wireless device including: a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one other wireless device in the set of wireless devices; a wireless transmitter (Tx) configured to transmit TTE signals representing an outgoing message to at least one other wireless device in the set of wireless devices; and a selectable / predefined data slot allocation and a selectable / predefined round timing that define one or more rounds of concurrent communications, wherein each wireless device is configured to interpret the incoming message based on the incoming message compared to the selectable / predefined data slot allocation, and transmit the outgoing message according to the selectable / predefined data slot allocation and the selectable / predefined round timing, such that each wireless device can communicate concurrently with the other wireless devices in the set of wireless devices.

[0043] The data slot allocation may include only 1 data slot in each round (e.g., exemplified in FIG. 6,7)

[0044] The data slot allocation may include 2 or more data slots in each round (e.g., exemplified in FIG. 9).

[0045] The wireless device may be configured to transmit the outgoing message in the same round as receiving the incoming message and in the same slot as the incoming message (e.g., exemplified in FIG. 6,7). (Thus, the wireless device may be configured to transmit the outgoing message at substantially the same time as receiving the incoming message.)

[0046] The wireless device may be configured to transmit the outgoing message in the same round as receiving the incoming message. The wireless device may be configured to transmitthe outgoing message in a different slot from the one or more slots of the incoming message (e.g., exemplified in FIG. 9).

[0047] The wireless device may be configured to transmit the outgoing message in a different round from when the incoming message is received (e.g., exemplified in FIG. 8, 10 - 14).(Thus, the wireless device may be configured to transmit the outgoing message at a different time from receiving the incoming message.)

[0048] The wireless device may be configured to transmit the outgoing message in at least one of same slots as the one or more slots of the incoming message (e g., exemplified in FIG. 8, 10).

[0049] The data slot allocation may include only 1 bit in each data slot (e g., exemplified in FIG. 11), or at least 2 bits in each data slot, or at least 3 bits in each data slot, or at least 4 bits in each data slot.

[0050] The data slots may include mutually different time slots (e.g., exemplified in FIG. 9 - 12).

[0051] The data slots may include mutually different frequency slots (e g., exemplified in FIG. 14).

[0052] The data slots may include mutually different code slots (e.g., exemplified in FIG. 14).

[0053] The properties of the incoming message may include a type of the data slot (optionally a time slot, a frequency slot or a code slot).

[0054] The TTE signals may include magnetic induction (Ml) signals, optionally including a carrier frequency of at least 1 kHz and no more than 50 kHz; and optionally of no more than 40 kHz, optionally of no more than 30 kHz, optionally of no more than 20 kHz, optionally of no more than 10 kHz, or optionally of no more than 5 kHz.

[0055] The wireless device may be configured to synchronise its clock using timing of the incoming message, optionally for a blasting delay.

[0056] The wireless device may be configured to generate the outgoing message based on the incoming message, optionally to retransmit with negligible delay if the incoming message is in a certain slot according to its timing / frequency / code.

[0057] The wireless device may be configured to generate the outgoing message based on any one or more of: the received TTE signals, optionally including a signal strength of the received TTE signals; stored data in the storage, optionally including a unique identifier (ID) of the wireless device in the set of wireless devices; a timer of the wireless device, optionally a periodic timer (referred to herein as "timer triggered"); and a sensor measurement made by the wireless device, optionally including any one or more of a temperature measurement, a pressure measurement, a moisture measurement, a shock measurement, a pH measurement, a humidity measurement, an acceleration measurement, an orientation measurement, and a magnetic field measurement, optionally including the sensor measurement exceeding a predetermined threshold (referred to herein as "event triggered").

[0058] The wireless device may include a housing configured and formed to protect the wireless device when deployed, wherein the TTE signals can travel through the housing.

[0059] The wireless device may include at least one microprocessor, and machine-readable storage connected to the at least one microprocessor, wherein the machine-readable storage includes: the selectable / predefined data slot allocation and the selectable / predefined round timing, and machine-readable instructions that control the at least one microprocessor to interpret the incoming message and transmit the outgoing message.

[0060] One or more embodiments disclosed herein include a system including a set of wireless devices, and one or more of: at least one listen-only wireless device that includes: a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one other wireless device in the set of wireless devices; and the selectable / predefined data slot allocation and the selectable / predefined round timing that define the one or more rounds of concurrent communications, wherein the listen-only wireless device is configured to interpret the incoming message based on the incoming message (or properties of the incoming message) compared to the selectable / predefined data slot allocation (e g., see FIG. 13), and at least one edge device that includes: at least one of: a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one other wireless device in the set of wireless devices, and a wireless transmitter (Tx) configured to transmit TTE signals representing an outgoing message to at least one other wireless device in the set of wireless devices; and the selectable / predefined data slot allocation and the selectable / predefined round timing that define one or more rounds of concurrent communications.

[0061] The edge device may include at least one non-TTE communications device for non- TTE communication of the incoming message and / or the outgoing message to a control / monitoring system.

[0062] One or more embodiments disclosed herein include a method including: receiving TIE signals representing an incoming message from at least one wireless device in a set of wireless devices; transmitting TTE signals representing an outgoing message to at least one other wireless device in the set of wireless devices; and wherein each wireless device is configured to interpret the incoming message based on the incoming message (or properties of the incoming message) compared to a selectable / predefmed data slot allocation, and transmit the outgoing message according to the selectable / predefmed data slot allocation and a selectable / predefmed round timing, such that each wireless device can communicate concurrently with the other wireless devices in the set of wireless devices.

[0063] The method may include one or more of: wireless blasting, signal survey, sensing, and / or localization of the wireless device.

[0064] One or more embodiments disclosed herein include a method including: determining, from a set of wireless devices, each configured for through-the- earth (TTE) communication to form a cluster or network in a site, a unique node identifier (ID) of each wireless device in the cluster or network; determining, from a control system that is external to the set of wireless devices, a set of device identifiers (IDs) of wireless devices deployed in the site; and comparing the unique node IDs to the set of device IDs to determine that one or more of the deployed wireless devices is not in reliable communication with the cluster or network; anddeploying a further wireless device to the set of wireless devices at a location in the site selected to improve the reliability of the communication with the determined one or more of the deployed wireless devices, or broadcasting a DISABLE command to the site to disable the determined one or more of the deployed wireless devices that are not in reliable communication with the cluster or network.

[0065] In the method, not being in reliable communication can include: not being in communication, or having communication reliability (e.g., signal strength) below a selected threshold.

[0066] The further wireless device may include at least one edge device, optionally configured for non-TTE communications.

[0067] The selecting the location for the further wireless device may include any one or more of: using a deployment map for the set of wireless devices, e.g., a blast plan; and testing the reliability of the communication of the determined one or more of the deployed wireless devices with the further wireless device at a plurality of test locations in the site, and selecting the test location with the highest tested reliability at the selected location

[0068] The deploying the further wireless device may include: carrying the further wireless device on a vehicle to the selected location; testing the reliability of the communication of the determined one or more of the deployed wireless devices with the further wireless device at the selected location; and deploying the further wireless device from the vehicle at the selected location.

[0069] The method may include controlling one or more wireless transmitter systems to broadcast the wireless DISABLE command to disable wireless devices with the missing IDs, wherein each DISABLE command includes one of the missing IDs.

[0070] Each wireless device may include: a wireless receiver (Rx) configured to receive TIE signals representing an incoming message from at least one other wireless device in the set of wireless devices; a wireless transmitter (Tx) configured to transmit TTE signals representing an outgoing message to at least one other wireless device in the set of wireless devices; and a selectable / predefmed data slot allocation and a selectable / predefmed round timing that define one or more rounds of concurrent communications.

[0071] Each wireless device may be configured to interpret the incoming message based on the incoming message (or properties of the incoming message) compared to the selectable / predefmed data slot allocation, and transmit the outgoing message according to the selectable / predefmed data slot allocation and the selectable / predefmed round timing, such that each wireless device can communicate concurrently with the other wireless devices in the set of wireless devices.BRIEF DESCRIPTION OF THE DRAWINGS

[0072] One or more embodiments of the present invention are hereinafter described, by way of example only, with reference to the accompanying drawings in which: a. FIG. 1 is a schematic diagram of a through-the-earth (TTE) wireless system; b. FIG. 2 is a block diagram of a TTE wireless device of the system of FIG. 1; c. FIG. 3 is a block diagram of an edge device of the system of FIG. 1; d. FIG. 4 is a block diagram of a storage in the wireless device of FIG. 2;e. FIG. 5 is a schematic diagram of an exemplary embodiment of the system of FIG. 1; f. FTG. 6 is a timing diagram with negligible processing / response times of a first TTE concurrent protocol (referred to herein as a "single-round single-slot concurrent protocol") of the exemplary embodiment of FIG. 5 ("negligible" in this context meaning the time difference of the incoming signals is negligible for the message / data detection / decoding algorithm / protocol to discern), g. FIG. 7 is a timing diagram with non-negligible processing / response times of the first TTE concurrent protocol of FIG. 6; h. FIG. 8 is a timing diagram with negligible processing / response times of a second TTE concurrent protocol (referred to herein as a "multi-round singleslot concurrent protocol") of the exemplary embodiment of FIG 5; i. FIG. 9 is a timing diagram with negligible processing / response times of a third TTE concurrent protocol (referred to herein as a "multi-round multi-slot concurrent protocol with time-divided concurrent data slots", or a "concurrent protocol with multiple time-ordered slots") of the exemplary embodiment of FIG. 5; j. FIG. 10 is a timing diagram with negligible processing / response times of a fourth TTE concurrent protocol (referred to herein as a "multi-round multi-slot concurrent protocol with time-divided concurrent data slots with each node sending or receiving but not both in each round") of the exemplary embodiment of FIG. 5; k. FIG. 11 is a timing diagram with negligible processing / response times of a fifth TTE concurrent protocol (referred to herein as a "multi-round multi-slot concurrent protocol with time-divided concurrent data slots, with 1 -bit data, and each node sending or receiving but not both in each round") of the exemplary embodiment of FIG. 5;l. FTG. 12 is a timing diagram with non-negligible processing / response times of the fifth TTE concurrent protocol of FIG. 10; m. FTG. 13 is a timing diagram with negligible processing / response times of a sixth TTE concurrent protocol (referred to herein as a "multi-round single-slot concurrent protocol with at least one node receiving only") of the exemplary embodiment of FIG. 5; n. FIG. 14 is a timing diagram with negligible processing / response times of a seventh TTE concurrent protocol (referred to herein as a "multi-round multislot concurrent protocol with frequency- or code-divided concurrent data slots") of the exemplary embodiment of FTG. 5; o. FIG. 15 is a top-view diagram of an array of 16 holes containing a network of nodes in an experimental example; p. FIG. 16 is a schematic diagram of a test system of the experimental example, showing 4 of the holes; q. FIG. 17 is a histogram of experimental example measurements, with the X axis being blast time error in microseconds and the Y axis showing frequency of occurrences of a certain time error; and r. FIG. 18 is a scatter plot of experimental example measurements, with the X axis showing different runs of the experiment, and the Y axis showing deviation from the mean of detonation latency in microseconds.DETAILED DESCRIPTIONOverview10073] Described herein is a through-the-earth (TTE) wireless system 100 and one or more TTE wireless communication processes or methods performed by the TTE wireless system 100, wherein the TTE wireless communication processes methods follow one or more TTE concurrent protocols defined by the system 100 and described hereinafter such that the TTE wireless communication processes or methods are referred to herein as "concurrent TTEcommunication methods", or “concurrent transmission” TTE communication methods because they implement a concurrent transmission (CT) multihop protocol. This concurrent communication (including concurrent flooding) is a multihop communication technique where multiple nodes simultaneously transmit a message across a network: instead of waiting for one node to finish before the next starts (as in traditional hop-by-hop methods), the nodes overlap their transmissions in a tightly synchronized way, e g., in a predefined time window. C.-H. Liao, G. Zhu, D. Kuwabara, M. Suzuki and H. Morikawa describe a form of “concurrent transmission” in a “LoRa” network in the following paper: "Multi-Hop LoRa Networks Enabled by Concurrent Transmission," in IEEE Access, vol. 5, pp. 21430-21446, 2017, doi: 10.1109 / ACCESS.2017.2755858.

[0074] As shown in FIG. 1, the system 100 includes: a. a set of wireless TTE communication devices Al . . . AN (also referred to herein as "nodes" that together form a TTE wireless "network") configured to communicate with each other by way of through-the-earth (TTE) wireless signal communication paths links (hereafter referred to wireless links, which in representative form are shown as dashed lines with double arrows in FIG. 1) either directly (e g., Al and A2 using the direct TTE link between them) or indirectly via one or more of the other nodes Al .. AN (e.g., Al and A(i-l) via A3, which is referred to herein as a "multihop" communication); b. at least one control / monitoring system 102 that is outside the network of nodes; and c. at least one edge device Bl .. BM (also referred to herein as an "edge node" because it generally defines an edge of the network) configured to communicate with: i. at least one of the nodes Al .. AN in the network, ii. the control / monitoring system 102, andiii. each other, when multiple edge devices are present, by way of wired and / or wireless communication links (shown as unbroken lines with arrows at each end in FIG. 1).

[0075] In order to provide the concurrent communication method, the nodes (which are the wireless devices Al . . . AN) that form the network are each configured to automatically, without human intervention, relay received data messages in a predetermined and coordinated fashion, specifically a concurrent fashion defined by the TTE concurrent protocols, as described hereinafter The communication methods described herein are referred to as "concurrent" because the nodes are configured to receive, to send, to relay and to generate data messages from and for the other nodes (thus across the network) according to the selectable / predefined TTE concurrent protocols; the nodes communicate in a coordinated and concurrent fashion using selectable / predefined communication slots (described hereinafter) and within selectable / predefined timing rounds (described hereinafter) such that data messages in the slots are relayed across the network both automatically and relatively rapidly, including generally having two or more of the nodes, e g., multiple or many nodes, sending and / or receiving the data messages at the same time. The nodes are configured to transmit their messages concurrently with each other, without waiting for communications channel availability (which is in contrast to using previous channel-sense systems), or without waiting for traffic control that requires knowledge of the network's topology before the data messages are sent (e.g., to avoid collisions, as in previous packet switched networks). Transmitting "concurrently" means all nodes in the network transmit substantially within the same time window, referred to herein as a "round", which is hard / firm-coded / programmable in all nodes by way of a selectable / predefined round timing TR and a selectable / predefined data slot allocation (e.g., a governing scheme can be predefmed / pre-ordained with the selectable data slot allocations and selectable round timings, and the actual data slot allocations and round timings for a set of communications may be dynamically selected in some cases: as described hereinafter, the stored selectable / predefined data slot allocation and the stored selectable / predefined round timing can be: (a) hardcoded in the wireless device; (b) encoded into the wireless device using an encoding machine; and / or (c) received by the wireless device in a wireless message using a non-concurrent network protocol, as needs arise): this is different from other TTE wireless device communications methods that use event-based messaging and routing. Collisions and destructive interference are problems faced byprevious communication networks, and have in the past been addressed by avoiding network communications at the same time. The system 100 enables two or more or many of the nodes within range of each other to transmit at the same time (thus concurrently), and the wireless device(s) receiving messages from the two or more or many nodes can receive them non- destructively, without requiring channel contention and network routing overheads.

[0076] As described hereinafter, the data messages may include data commands, e g., as described in Appendix A.

[0077] The nodes in the set are configured to transmit their outgoing messages concurrently by way of at least one selectable / predefined round timing TR, stored in the nodes (in storage), that define the one or more selectable / predefined timing rounds of concurrent TTE (data) communications, as described hereinafter.

[0078] Tn the concurrent communications disclosed herein, the slots are for data, and the slots referred to herein are not necessarily only time slots for transmitters as in prior art protocols like time-division multiple access (TDMA).

[0079] The selectable / predefined communication slots may be referred to as "floods" if they are the same everywhere in the network at once, and the selectable / predefined slots enable the data messages to "flood" (without requiring routing) across the network according to the selectable / predefined round timing TR. In flooding implementations, described in further detail hereinafter, the wireless device is configured to generate the outgoing message by retransmitting the incoming message, including with a zero / negligible delay and / or a defined delay, such that the wireless device transmits at substantially the same time as, or in synchronised rounds with, with other wireless devices and edge devices in the network.

[0080] The nodes are configured to receive and transmit their messages according to the selectable / predefined data slot allocation that is stored on each of the nodes in the network, and this slot allocation allows each node to deal with collisions caused by the node receiving incoming messages from two or more others of the nodes at the same time.

[0081] The system 100 is configured to provide relatively rapid communication across the network in one direction and in two directions, including: from the edge node(s) into the network of nodes (referred to herein as relaying "inbound" messages); from one or morenodes in the network to the edge node(s) (referred to herein as relaying "outbound" messages, and in this case the “edge node” may also be referred to as an “exit node”); both inbound and outbound (referred to herein as "two-way communications"); and from one or more nodes in the network to one or more other nodes in the network without necessarily reaching an edge node (referred to herein as relaying "cross network" messages). A communication pattern provided by the messages may therefore be any one or more of the following: one-to-all, one- to-one, many-to-many, many-to-one, all-to-all (e g., depending on which communications task is being performed, e g., a task from Appendix A). When the communication is for outbound messages (towards the edge node(s)), having a plurality of the edge nodes receive the outbound messages may be advantageous in some applications: in this case, adding more exit nodes / surface nodes at various locations can help accelerate the communication, reducing the total number of hops to flood entire network, and subsequently improve time synchronisation performance because the longer the flood message is in the network, the more its time synchronisation can deteriorate. In examples, the one or more communication methods propagate data messages from the edge nodes to deeper nodes (further into the network than the edge nodes) via shallower nodes, which are closer to the edge nodes (and are therefore referred to as “intermediate nodes”). In other examples, the one or more communication methods propagate data messages from the deeper nodes (or “deep nodes”) to the edge nodes via the shallower nodes (or “intermediate nodes”).

[0082] To provide the concurrent communication methods, the set of nodes is configured such that any nodes in the set that are not within direct wireless range of each other can still communicate because an intermediate one of the nodes in the set acts as a relay in order to relay data messages further than the wireless range of any one node. For example, a first one Al of the nodes is configured to relay received signals to others (A2, A3, A4, as shown in FIG. 1) of the nodes within wireless range of the first one Al . Accordingly, in operation, at least one relevant data message is relayed by at least one intermediate node in the set of nodes that form the network. Thus, the TTE communication protocols described herein are referred to as "multihop" protocols, or "multihop TTE concurrent transmission protocols", because each message can travel over a plurality of the wireless links (referred to as "hops") from or to the edge nodes. Accordingly, the network may be referred to as a "multihop network" or a "multihop wireless communications network" or a "concurrent multihop TTE wireless communications network". By way of the TTE network, the system 100 providesone-way and / or two-way wireless (2WW) TTE communications between the nodes in the network (e.g., buried MI devices), and to / from the control / monitoring system 102 including by multiple hops. The nodes, and thus the system 100, are configured to perform or provide TTE concurrent communication between the (buried / deployed) nodes. The TTE concurrent communication methods allows for network communications without traffic management or information about the network topology.

[0083] As shown in FIG. 1, the nodes of the system 100 are each positioned (e.g., arranged or deployed) on and / or in an opaque medium 108, which can include rock / earth / ice / stemming / foundations / structures depending on the application. The opaque medium 108 is opaque to, thus substantially blocks, line-of-sight communications, e g., optical communications or radio communications above 3 MHz (e g., WiFi, cellular telephone); however, the opaque medium 104 substantially allows propagation of the TTE wireless links (shown as dashed lines with double arrows in FIG. 1), although the extent of attenuation of TTE wireless links depends on the nature / composition of the opaque medium 108 as will be understood by individuals having ordinary skill in the relevant art. The opaque medium 108 generally includes materials that substantially inhibit / block visible and radio communications above 3 MHz, including ore, rock, broken rock, stone, rubble, debris, gravel, cement, stemming material, bulk explosive, soil, dirt, sand, clay, mud, sediment, snow, ice, hydrocarbon fuel reservoirs, civil infrastructure, building materials, construction materials, earth, coal, stockpiles of ore / waste, tailings, landfill, concrete (including in civil engineering structures, e.g., in dam walls), foliage and / or tree cover. It is noted that the term "through- the-earth" (TTE) refers to communication not only through "earth" but through the opaque medium 108, which may include non-earth materials mentioned hereinbefore. The edge nodes Bl .. BM of the system 100 are position in a navigable medium 110 that is above / outside a surface 112 of the opaque medium 108: the navigable medium 110 can include open air (for surface applications), underground tunnels (for underground applications), or water (for marine applications) — the edge nodes may therefore also be referred to as “surface nodes” on or at the surface of the opaque medium 108. In contrast to the opaque medium 108, the navigable medium 110 substantially allows one or more of: the wired and / or wireless communication links (shown as unbroken lines with double arrows in FIG. 1) from the edge nodes Bl .. BM to each other (if there is more than one edge node) andto the control / monitoring system 102; and movement of the edge nodes Bl BM, e.g., if one or more of the edge nodes Bl .. BM includes or is attached to a vehicle.

[0084] Each node (which is a wireless device Ai, e.g., a device Ai configurable or configured for wireless TTE signal communication) has a TTE wireless range that depends on properties of material in the opaque medium 108 that surrounds the node — e.g., rock around a borehole 114 and stemming / bulk explosive in the borehole 114 of FIG. 1 in which at least one of the nodes is deployed, e.g., electrical and magnetic properties. The wireless range of each node also depends on one or more of the following, depending on the implementation: a transmit power of the wireless device Ai, transmission noise of the wireless device Ai, receiver noise of others of the wireless devices, background noise (or electromagnetic interference), and placement of the nodes (e.g., based on a blast design that defines borehole spacing and deck spacing of the nodes along each borehole 114). The wireless range of any one direct single link (or "hop") can change between communication events, e g., over days, weeks or months, e.g., with ground movement or ground moisture changes.

[0085] In FIG. 1, only nearest-neighbour TTE links (dashed lines) are shown, but it is possible for a plurality (e.g., dozens) of the nodes to be in range of a direct single link (or "hop") because the range of each hop is determined by implementation, situational, and / or environmental details as described hereinbefore.

[0086] In some embodiments, the edge nodes Bl .. BM can operate as "source" nodes by initiating, transferring, or relaying TTE signals into the network formed by the nodes and the edge nodes. When these edge nodes initiate the signals, they may be referred to as the “first transmitters” or "communications initiators". The edge nodes can additionally or alternatively operate as "sink" nodes by receiving TTE signals from within the network.

[0087] In some embodiments, ones of the non-edge nodes Al .. AN, can operate as "source" nodes by initiating, transferring, or relaying TTE signals into the network formed by the nodes and the edge nodes. When these edge nodes initiate the signals, they may be referred to as the “first transmitters” or "communications initiators". Thus, the communication methods can propagate the data messages from the deeper nodes (or “deep nodes”) to the edge nodes via shallower nodes; in embodiments, the deep nodes are nodes that require atleast two hops (thus “multihop”) to reach one of the edge nodes, e g., A2, A4, Ai and AN can be referred to as “deep nodes” in FIG. 1.

[0088] It can be noted that, in commercial blasting applications, some (though not necessarily all of) nodes Al .. AN can include / carry a blast initiation device, e.g., a primer, a detonator or an optical initiation device configurable or configured to initiate and / or detonate an explosive composition or medium, and possibly or optionally others of nodes Al .. AN exclude, lack, or omit a blast initiation device; and the edge nodes Bl .. BM typically need not or do not include / carry a blast initiation device.

[0089] In some implementations, as show in FIG. 1, one edge node may connect the network to a blasting system with a firing system 106, e g., to transmit FIRE commands to the nodes.

[0090] Although FIG. 1 shows three edge nodes Bl .. BM, the system 100 may have just one edge node, or two, three or more edge nodes, depending on implementation details. In some implementations, the system 100 may include multiple or many edge nodes, e.g., a swarm of edge nodes, configured to transmit messages to the nodes and / or to collect messages from the nodes in parallel, and thus more rapidly If there are two or more of the edge nodes Bl . BM, they can be configured to communicate with each other by the wired and / or wireless communication links (shown as unbroken lines with double arrows in FIG. 1): for instance, the edge nodes Bl .. BM can be configured to communicate with each other (and the control / monitoring system 102) by prior art radio-frequency (RF) communication methods (which provide the wired and / or wireless communication links), prior art wired communication methods, or prior art TTE communication methods. The wired and / or wireless communication links may generally be through-the-air (TTA) or line-of-sight (LOS) or substantially LOS links (hereafter “LOS links” for purpose of brevity and simplicity) provided by prior art LOS methods and configurations of the edge nodes Bl .. BM, e g., as described in International Patent Application No. PCT / SG2020 / 050370. When the wired and / or wireless communication links (unbroken lines with double arrows) include one or more wireless links, e.g., RF radio links, the edge nodes Bl .. BM may be a mobile surface radio devices that can have changing connectivity during performance of the methods by the system 100, including because one or more of the edge nodes Bl . BM, e g., each attached to or incorporating a vehicle (e g., as described in International Patent Application No.PCT / SG2020 / 050370, and / or International Patent Application No. PCT / SG2025 / 050084), is moving during the methods (and thus during the network communications described herein). When the wired and / or wireless communication links (unbroken lines with double arrows) include one or more wired links, these can include a communications cable (e.g., one or more wires) between the edge nodes. Depending on the wired and / or wireless communication links used in an implementation of the system 100, the edge nodes may be referred to as "MI / RF / LOS devices" because they are configured to communicate by way of one or more of the following: the TTE communication methods (even if not necessary through rock etc., using the same frequencies etc.), the radio-frequency (RF) communication methods, and / or LOS communications. In at least some implementations, having two or more of the edge nodes can provide one or more of the following: scalability because multiple edge nodes allow the system 100 to handle more data and more users, distributing the load across different locations; redundancy because having multiple edge nodes increases the reliability of the system 100, e.g., if one edge node fails, others can take over its tasks, ensuring continuous service; proximity because placing the edge nodes closer to the nodes reduces latency, e.g., by processing data locally on the edge nodes rather than sending it back to a central server in the control / monitoring system 102, or to a set of cloud-based servers associated therewith; specialization because different ones of the edge nodes can be optimized for specific tasks or services, improving overall system performance, depending on the implementation; and geographical distribution because multiple edge nodes spread across various locations can serve a larger geographical area, providing better service to the nodes in different regions of the system 100, e.g., for large blasts or surveys.

[0091] Although FIG. 1 shows the edge nodes in the navigable medium 110 (e.g., air), the edge nodes can be placed in the navigable medium 110, e.g., in the boreholes 114, at least in certain implementations; however, they remain coupled or connected to the other edge nodes and / or the control / monitoring system 102 by way of the wired or wireless links (unbroken lines). For example, the edge node Bj in FIG. 1 may be arranged / buried in an outer portion of the borehole 114 that contains the node A(i-l), and may communicate by the wired or wireless links out of the borehole 114 Alternatively, one or more of the edge nodes may be arranged as a "topbox" near or at a mouth of the borehole 114 containing one of the nodes — in such an arrangement, the TTE links (broken lines) along the borehole 114 may include one or more range extension systems, e.g., as described in International Patent Application No.PCT / SG2022 / 050714, e.g., for example nodes in deeper holes and / or in rock types exhibiting high magnetic-susceptibility or conductivity, e.g., magnetite, rendering traditional magnetic induction (MT) TTE unreliable.

[0092] As shown in FIG. 1, the control / monitoring system 102 is connected to the edge nodes Bl .. BM by further wired and / or wireless communication links (shown as unbroken lines with double arrows in FIG. 1), and by a non-TTE network 104. The edge nodes Bl .. BM can send data messages to the control / monitoring system 102, and / or the edge nodes Bl .. BM can receive data messages from the control / monitoring system 102, depending on the implementation. As shown in FIG. 1, the control / monitoring system 102 may include a firing system 106 when used for blasting applications. These wired and / or wireless communication links (shown as unbroken lines with double arrows in FIG. 1) can include prior art wired and / or wireless data connections, e.g., secure data connections, such as Ethernet connections, Internet connections, and / or mine network connections. The firing system 106 may include a shotfirer or central controller, as well as one or more blasters, including as described in the prior art, e.g., in ORICA's Omni Remote Blasting System (ORBS) and / or in International Patent Application No. PCT / SG2024 / 050394. The monitoring system 102 may include monitoring systems that gather and record measurement data from the nodes, e g., for seismic surveying or environmental monitoring applications.|0093| The system 100 may include two or more subnetworks (also referred to herein as "clusters") with mutually different slot allocations, e g., different frequencies, to allow the system 100 to use two or more concurrent communication "floods" at the same time without interference. In an example blasting application, a blast bench contains 100 primers There are two edge nodes: B 1 at the north, and B2 at the south. B 1 and B2 coordinate with each other over the wired and / or wireless communication links, including a fast RF link. Bl communicates with cluster 1 (50 primers near the north of the bench) with a data slot comprising frequency 1, and B2 communicates with cluster 2 with a data slot comprising frequency 2. A concurrent communications task can happen for both clusters simultaneously (e g., the STATUS task). Cluster 2 can ‘reuse’ rounds from cluster 1 since it operates on a separate frequency. This system could reduce latency and energy consumption (because fewer timeslots are needed).Wireless devices Al ... AN ("nodes")

[0094] As shown in FIG. 2, each of the nodes includes: a. at least one circuit-based processor (which can include one or more microcontrollers or microprocessors, or similar processor circuit based on electromagnetic circuit components, powerable by an electrical power source); b. machine-readable storage connected to, and readable by, the at least one circuit-based processor; c. a wireless receiver (Rx) configured to receive through-the-earth / rock (TTE) signals from at least one other wireless device in a set of wireless devices; and d. a wireless transmitter (Tx) configured to transmit TTE signals to at least one other wireless device in the set of wireless devices.

[0095] As shown in FIG. 4, the storage includes machine-readable instructions that control the at least one circuit-based processor to: a. interpret the incoming message based on the incoming message (or properties of the incoming message) compared to a selectable / predefined data slot allocation in the storage (the message and its properties may be timing / frequency / code, and the interpretation may be complicated or simple: e.g., (i) interpret a header of the incoming message based on stored interpretation instructions that define how the incoming message it to be retransmitted, or how the outgoing message is to be generated, including whether to transmit substantially immediately (thus after a negligible delay) or after a defined delay (defined in the storage of the node, and / or in the header data); or (ii) retransmit substantially immediately (thus with negligible delay), or after a defined delay (defined in the storage of the node, and / or in the header data), if the incoming message is in a certain slot according to its timing / frequency / code — "negligible" in this context meaning the time difference of the incoming signals is negligible for the message / data detection / decoding algorithm / protocol to discern, andb. generate an outgoing message for the transmitter based on any one or more of i. the incoming message, ii. the received signals, optionally including an MI signal strength of the received signals (e.g., represented by a signal-to-noise ratio, SNR); iii. stored data in the storage, optionally including a unique identifier (ID) of the wireless device in the set of wireless devices, and iv. sensor measurements made by the wireless device, optionally including any one or more of a temperature measurement, a pressure measurement, a moisture measurement, a shock measurement, a pH measurement, a chemical and / or biological substance or species measurement, a humidity measurement, an acceleration measurement, an orientation measurement, and a magnetic field measurement (e g., as described in International Patent Application No.PCT / SG2020 / 050370); and c. transmit the outgoing message according to: i. the selectable / predefined data slot allocation (transmission always occurs in a selected slot, even if there is just one slot for the whole network), and ii the at least one selectable / predefined round timing, stored in the storage, that define one or more rounds (the slots are repeated in each round, e.g., in FIGs. 8 to 13, Round 2 has a repeat of the slots in Round 1), of concurrent communications (even for frequency / code multiplexing, the protocol has at least one round).

[0096] The selectable / predefined data slot allocation combined with the selectable / predefined round timing together control the wireless device to communicate concurrently with the other wireless devices in the set of wireless devices.

[0097] The slot allocation is required by the nodes in advance of operating according to the concurrent protocol so the nodes are able to interpret the incoming signals. The data slot allocation defines a set of data slots for the nodes and the set of nodes, thus allowing each node to transmit concurrently with others in the set of nodes, which together form the concurrent multihop network. The timing of the one or more rounds is required in advance by each node so the node transmits according to the protocol, thus allowing the other nodes to receive the outgoing message without destructive interference. The data slot allocation may also be referred to herein as a "transmission slot allocation" because it allocates the data slots into which the data is transmitted, as well as received.

[0098] As the data slot allocation controls the TTE transmitter Tx to transmit concurrently with the at least one other node in the set of nodes, there is no need to stop the nodes from "talking" over the top of each other. Furthermore, routing of the messages may be unnecessary, and the topology of the network (i.e., arrangement of the nodes in the network) may be irrelevant. By avoiding the need for routing in the network, a significant "overhead" can be avoided, thus reducing the time / energy required for the communications compared to communications in pre-existing networks.

[0099] The data slot allocation can be in the form of a list / schedule of different slots that fit within each round.

[0100] The round may repeat for each hop, i.e., each hop may require one round, e.g., described hereinafter with reference to FIG. 8 and FIG. 10.

[0101] The outgoing message is transmitted after the incoming message has been received and interpreted.

[0102] The outgoing message may be the same as the incoming message, or different (e.g., some protocols may have a counter value C with the message that is incremented by each hop, e.g., described hereinafter with reference to FIG. 8).

[0103] The data slot can be a time slot, a frequency slot, or a code slot, depending on the selected protocol, referred to respectively as:a. time divided concurrent data slots, wherein the slots in each round have mutually non-overlapping times allocated; b. frequency divided concurrent data slots, wherein the slots in each round have mutually non-overlapping frequencies allocated; and c. code divided concurrent data slots, wherein the slots in each round have mutually non-overlapping codes allocated, e.g., codes selected according to prior art spread-spectrum encoding techniques.

[0104] The data slot allocation and the round timing are referred to being "selectable / predefined" because they may be selected and / or predefined differently in different embodiments. Tn embodiments, the slot allocation and the round timing can be hardcoded when the nodes and manufactured or sold, can be encoded on site (e.g., on the mine bench by an encoding machine), or sent to the nodes by a non-concurrent protocol supported by the nodes (before commencement of the concurrent methods). The slot allocation and the round timing may be stored / written into the storage by: a. an encoding machine, e g., ORICA's encoder controller that programs individual wireless primers with unique encrypted codes, prior to placement in the ground / structure; and / or b. a TTE wireless message received by the wireless device before or after placement / deployment in the ground / structure, e g., from a TTE broadcast antenna (e.g., ORICA's MI quadloop antenna), or from a (potentially mobile) antenna (e.g., as described in International Patent Application No. PCT / SG2020 / 050370, "Commercial blasting systems"), or from another of the wireless devices (e.g., as described in International Patent Application No. PCT / ZA2019 / 050046, "Bidirectional wireless detonator system", 'Detnet').

[0105] The actual modulation / demodulation frequency of the nodes, including when there are frequency slots and when just one frequency is used in time slots, can be a fixed factory tuning or resonance frequency, e.g., by selecting or controlling one or more resonance frequencies of the node, including by tuning a “resonant tank” of the Rx antenna and / or theTx antenna of the node Ai, e.g., as described in International Patent Application No PCT / SG2024 / 050396.

[0106] The machine-readable instructions can control the at least one circuit-based processor to push the outgoing message to the TTE transmitter until the entire outgoing message has been pushed if the message size is greater than the corresponding slot size, e.g., over 1 bit, e.g., at least 2 bits, or at least 3 bits, or at least 4 bits.

[0107] The nodes may optionally include an internal or connected electrical energy source as shown in FIG. 2, e.g., a battery or super capacitor that can be charged up prior to or at loading / deployment time, e.g., by close-proximity induction charging, and placed in the ground / structure, e g., as described in International Patent Application No.PCT / SG2015 / 050322, "A wireless initiation device". Altematively / additionally, the electrical power may be provided from a remote source, e.g., as described in International Patent Application No. PCT / AU1998 / 000929, "Controlled electromagnetic induction detonation system for initiation of a detonatable material" ('Gavrilovic').

[0108] As shown in FIG. 2, the TTE transmitter Tx is typically separated and electromagnetically / electrically isolated from the TTE receiver Rx to avoid the TTE transmitter Tx jamming or damaging the TTE receiver Rx, e g., as described in International Patent Application No. PCT / SG2024 / 050396.

[0109] The machine-readable instructions can control the at least one circuit-based processor to include recognize the unique ID of the node in an incoming message in order to confirm that the incoming message is intended for the unique node, e g., when the incoming message includes a new DELAY time for an associated blast initiator (including in a table of DELAY times), or when the incoming message is requesting a STATUS of the node.

[0110] The node may be configured to implement a capture effect, when the TTE receiver Rx is receiving TTE signals from more than one source, by processing (or "listening to") only the loudest one of the received TTE signals. The capture effect is one mechanism of nondestructive interference, e.g., when Al receives signals from A2 and A3 which overlap in time (received concurrently). The signals could have some relative time delay or phase shift (or they can theoretically be different data). Ordinarily these overlapping messages mightcause a collision and reception would fail; however, the node can be configured to start receiving from A2 and then when a stronger signal arrives from A3 later, switch to A3 and disregard A2.[OHl] The node may be configured to use a power boost to increase its TTE range, e.g., if no other node sends a data message in response to a request. The power boost is described in International Patent Application No. PCT / SG2024 / 050396.

[0112] The node generally includes at least one protective housing configured and formed to protect the node when deployed, including to protect the electrical / electronic elements of the device (including the transmitter Tx and receiver Rx components) from impacts during deployment, from water, and / or from pressure and chemical damage while waiting in the hole (e g., until after a FIRE command has been received and processed), whilst still allowing the TTE signals to travel through the protective housing from and to the transmitter Tx and receiver Rx components, specifically the antennas of the transmitter Tx and receiver Rx components. The protective housing thus seals and protects the wireless device from water and impact when deployed in a mining / blasting environment, and the housing is at least partially transparent to the TTE signals. The at least one protective housing may include polymer shell pieces, e g., injection moulded, that encase one or more printed circuit boards (PCBs) of the electrical / electronic elements of the node. The protective housing may include potting material to insulate and protect the electrical / electronic elements. The at least one protective housing can be substantially sealed against moisture to protect the electrical / electronic elements, e.g., the polymer shell pieces may mutually connect and seal, e.g., by adhesives. Inside the protective housing, when the TTE signals are MI signals, the transmit antenna may include potting material around and encapsulating some or all of the electrical / electronic elements in order to mechanically protect, hermetically seal (e.g., quasi- hermetically seal) and / or magnetically shield the transmit antenna away from other electronics components, and thus: protect the other electronics components, including signal reception circuitry, from strong MI fields of the transmit antenna, and / or mitigate the transmit antenna being impacted by nearby electronics / conductive material that could weaken its transmit power, e.g., by absorption or changing the resonant frequency.Built-in Synchronization

[0113] The nodes generally require temporal alignment of the rounds in time, therefore the nodes can use start and / or stop times of the data messages in the rounds (and in the slots) to stay synchronised (or "synced") with the other nodes in the network, even if the protocol uses frequency slots or code slots, thus network synchronization can be attained inherently due to the selectable / predefined data slot allocation and the selectable / predefined round timing, without additional signalling, and this can be useful in some applications, e.g., for blast delays in blasting, and for synchronized measurements in seismic surveying.Node Storage

[0114] The circuit-based processor and / or the node storage, e.g., a RAM, ROM or EEPROM chip, is configured to retain its stored data in a low power state or an ultra-low power state, e.g., a SLEEP state, and / or the storage may include non-volatile memory such that the storage can be essentially completely or completely powered off, e.g., during a blast cycle, and then powered on, e.g., by a WAKE command.

[0115] For a simple concurrent protocol, described with reference to FIG. 6 and FIG. 7, the storage is programmed with the following 1 parameter to provide the concurrent communications: the selectable / predefined data slot allocation, which can be one "time slot", "frequency slot" or "code slot", which can be the same for all nodes in the set, and there is no need to store or use node identity information (the unique ID) in the storage for the simple implementation, e g., a message flood, and the selectable / predefined round timing is the same as or calculable from the one data slot.

[0116] In a more complicated implementation, described with reference to FIG. 8 to FIG. 14, the storage is programmed with one or more of the following parameters to provide the concurrent communications: a. the slot allocation (including any guard bands), which can include the set of slots timings, the frequencies of any frequency slots, and / or the codes of any code slots (depending on which methods are provided); b. the round timing, i.e., the timing for the rounds, if it is different from the total of the slot times-if the round timing is equal to or calculable from the slot timings, then the round timing need not be stored separately;c. optionally a parameter for limiting the number of rounds that a node participates in; d. the identities of data assigned to particular slots if there is more than one slot; and e. the identity of the node, referred to as the unique ID of the node or the "node ID".

[0117] For time slots, the guard bands are additional times at either side of a time slot that are not allocated. The guard bands allow for imperfect sync between the nodes, so that neighbouring slots do not overlap. For frequency slots, the guard bands are additional frequencies at either side of a frequency slot that are not allocated, also to mitigate overlaps between adjacent slots.

[0118] The parameter for limiting the number of rounds allows power usage to be controlled If the round is repeating with the same data (e.g., a flood), the repeats can help with reliability (multiple chances of being received); however, the nodes should stop after a certain number of rounds to limit power use.

[0119] The node ID can include one or more of the following: a. a unique device ID in the set of devices, and the unique device ID may include or correspond to a device ID, e.g., provided by and associated with an external control system (e g , a primer ID in a blast plan); b. for time slots, an index / ordering number corresponding to a slot in the list of time code slots (which can be different from the unique device ID), which can be called a "time slot ID", wherein the index / ordering number can include the time-slot time or a unique slot identifier (ID) in the set of slots; c. for frequency slots, a frequency slot ID (which can be different from the unique device ID) that can include the actual modulation / demodulation frequency / ies or a unique slot identifier (ID) in the set of slots; andd. for code slots, a code slot ID (which can be different from the unique device ID) that can include the actual slot modulation / demodulation code / protocol, or as a unique identifier of the actual odulation / demodulation code

[0120] Each node may know its slot time / frequency / code in storage without necessarily having a node ID number explicitly in storage. For example, if node Ai has slot frequency Y kHz in its storage; when the flood comes along, it contributes new information (e.g., STATUS) in slot Y, and in all other slots it simply repeats what it receives.

[0121] The node can be configured to compare its unique ID to a list of ID numbers in the storage to determine its relative ordering. In blasting applications, a ‘delay table’ or blast design is a list of primer delay times. If the list contains just a column of times, then the corresponding primers are implied, e.g., the first delay number is implicitly assigned to primer 1, etc. Alternatively, there could be a second column explicitly listing the primer ID numbers corresponding to the column of delays, and then the primers need not be listed in a particular order. The ID numbers could be a local ID number (e.g., small integers: 1, 2, 3, ...) used within the blast, or alternatively the ‘delay table’ in storage could use a primer’s serial number (e g., a long alphanumeric string, unique to each primer in the world).

[0122] The storage can include data representing a plurality of the protocols, thus allowing the system 100 to use a plurality of mutually different communications protocols in one application or operation. The plurality of stored protocols may include two or more mutually different communication protocols, including two or more concurrent communication protocols. The non-concurrent communication protocols can include prior art communication protocols. The storage is programmed for the node to provide at least one concurrent protocol, and optionally more than one concurrent protocol in sequence, e.g., switching from a first concurrent protocol to a second concurrent protocol, e g., for different network tasks. Different protocols are therefore selected for different network tasks, e g., flooding for SYNC / ARM tasks and routing for other tasks, depending on the size of the network. Different communications tasks occur at different times, and it can be that the network is organised differently for each product use case, and workflow step within it. For example, an edge node in the form of a moving / roving surface radio device may be present at some tasks and not at others, and therefore different protocols are selected for the differenttasks. For some tasks, there may be the option of using a WEBGEN broadcast from a large MI antenna, e.g., as described in International Patent Application No. PCT / SG2024 / 050394, rather than or in addition to using the multihop network described herein. In blasting applications, the system 100 can adopt multiple protocols and select one based on ground condition, communications task type, bench size (node count), etc. For instance, when checking primer status, the system 100 may adopt the multi -round multi-slot concurrent protocol with time-divided concurrent data slots, with 1-bit data, and each node sending or receiving but not both in each round, whereas when sending timing table, it can utilize the multi-round single-slot concurrent protocol.10123] As described hereinafter, different concurrent TTE communication protocols can have any one or more of: a. different numbers of slots per round; b. simultaneously or substantially simultaneously send and receive, e.g., see FIG. 6 and FIG. 7; c. non-overlapping slots for send and receive, e.g., see FIG. 8 to FIG. 13; d. non-overlapping rounds for send and receive, e.g., see FIG. 10; e. 1-bit slots, e.g., see FIG. 11; f. non-negligible processing times between receive and send, e.g., see FIG. 6 and FIG. 12; g. listen-only nodes, e g., see FIG. 13, and h. different slot types, e g., for frequency or code slots see FIG 14

[0124] Typical embodiments may use time slots instead of frequency slots or code slots. In an example with a plurality of protocols for blasting applications: a. Protocol 1 may be an outbound FIRE flood with rounds of just one slot (noting that time / frequency / code slots can be equivalent when there is just one slot); andb. Protocol 2 may be a STATUS communications task, with time-slotted status messages and multiple slots (e.g., see FIG. 9 to 12), with one slot allocated for every node’s status info.

[0125] As shown in FIG. 2, the node Ai may include a clock connected to the circuit-based processor, and the machine-readable instructions in the storage may control the circuit-based processor to generate and send a data message based on a stored time trigger in the storage, e.g., to gather periodic sensor reports.

[0126] As shown in FIG. 2, the node Ai may include one or more sensors, and the machine- readable instructions in the storage may control the circuit-based processor to generate and send a data message based on an event trigger from one of the sensors, e.g., a sensor alarm event such as over temperature.

[0127] The machine-readable instructions in the storage may control the circuit-based processor to gather reliability data to send in a data message, e.g., representing network retransmissions, data slot hopping, and network coding detected by the node.

[0128] In embodiments, the nodes may be configured to communicate with a substantially 1.8-kHz MI carrier frequency, and each node may have three mutually orthogonal coil antennas.

[0129] In some monitoring embodiments, at least some of the nodes may be configured as location markers with the components of the marker apparatus (102) described in International Patent Application No. PCT / SG2025 / 050084 and / or International Patent Application No. PCT / SG2023 / 050551.

[0130] In blasting embodiments, at least some of the nodes may be configured as initiators or primers, including a detonator as shown in FIG. 2, e.g., as described in International Patent Application No. PCT / SG2023 / 050678.

[0131] It can be noted that monitoring embodiments and blasting embodiments can be combined.Edge Nodes

[0132] As shown in FIG. 3, each of the edge nodes Bl .. BM includes substantially the same elements as the each of the nodes Al . . . AN, as well as any one or more of the following: a. a vehicle, e g., a drone (such as an aerial or a land-based drone, which can be remotely piloted or autonomous) as described in International Patent Application No. PCT / SG2020 / 050370 and / or International Patent Application No. PCT / SG2025 / 050084; b. an RF radio for establishing and communicating using the MI / RF / LOS links with RF signals and prior art protocols (e g., as described in International Patent Application No. PCT / AU2006 / 000085, "Wireless detonator assemblies, and corresponding networks", and / or using commercially available RF radio equipment); and c. a network interface for connecting to the Internet, and optionally to a remote or cloud server using commercially available networking equipment.

[0133] In embodiments, the edge nodes Bj (potentially comprising or entirely comprising "above-ground" hardware) may include substantially the same elements as the nodes Ai (potentially referred to as comprising or entirely comprising "under-ground" hardware) albeit selected to be tolerant to higher noise, and / or to be movable during operation of the system 100.Slot Types

[0134] As described hereinbefore, the data slot allocation may include one or more of: a. a unique time slot in a transmission schedule, b. a unique frequency in a frequency schedule, and c. a unique code in a code schedule.

[0135] Some implementations of the system 100 define the slot allocation using one or more time slots, which is herein referred to as having "time divided concurrent data slots".

[0136] The data slot allocation defines a unique set of data slots for the nodes in the set. The slots may include information corresponding respective nodes, or information not corresponding to respective nodes The TTE transmitter Tx transmits any outgoing message in the data slots. The unique data slot allocation for each unique protocol is stored in the storage of each node, as described hereinbefore, before the initiation of the concurrent messaging The unique data slot allocation determines the unique set of data slots, so the provided communication between the nodes may be referred to as "deterministic" or determined in advance of the communication occurring. The slot allocation is determined in advance. The term "deterministic" may also be used because the processing on the node takes a well-controlled or predictable amount of time, e.g., as described hereinafter with reference to FIG. 12.|0137| All nodes in the set of nodes under consideration (which can be the network or the cluster) are controlled to select the same concurrent protocol, and thus the same slot allocation and round timing, e.g., at manufacture or by encoding machine or by in-situ signalling, e.g., a prior art non-concurrent network sync protocol before starting the concurrent protocol. All nodes in the set get onto the same time base, i.e., synchronize their slots and fix their clock rates (e g., the vertical lines in FIG. 8 to FIG. 14). Optionally, clock sync for the clock in the node Ai can be included in any / all time slot and / or any round, as mentioned hereinbefore. Calibrating the clock rate and the clock skew may be required before starting the concurrent protocol.

[0138] To get all nodes on the same time base, the nodes include "deterministic" firmware, meaning the processing on the node takes a well-controlled or predictable amount of time. The keep the nodes synchronised, the node processing needs to be essentially the same or the same for each node, and this is referred to as "deterministic" processing in the node

[0139] One method of synchronizing the nodes before concurrent communication includes POLING, which limits each node to have only 1 buffer sample, then each node checks for a new message every sample, therefore there is a high likelihood of all nodes checking at once in a synchronized manner. The POLING may include the circuit-based controller processing sample-by-sample using two buffers, one being processed whilst the other is being filled. The processing time is selected to be less than buffer filling time (e.g., 100 ms). Once allnodes are synchronised, with their slot allocations and round timing, they are ready for concurrent communications.Slot Allocations

[0140] The slot allocations for each concurrent TTE protocol can be: a. arbitrary slot allocations; b. nodewise slot allocations; or c. taskwise slot allocations.

[0141] When the slot allocations are arbitrary slot allocations, each slot can include different data, and the stored data slot allocation defines multiple unique data slots for respective data containers, e g.: a. Slot 1 carries Data 1 ; b. Slot 2 carries Data 2; c. Slot 3 carries Data 3; and d. etc. if there are further slots.

[0142] The meaning of Data 1 etc. in the protocol can be different depending on the application / operation, e.g., each data message can carry data from different ones of the sensors, or carry different command, e.g., from the list in Appendix A.

[0143] When the slot allocations are nodewise slot allocations, each slot carries data to or from one node, so one slot is required / used for each node in the network (or in a subnetwork), e.g.: a. Slot 1 carries Data relating to Node 1; b. Slot 2 carries Data relating to Node 2; c. Slot 3 carries Data relating to Node 3; andd. etc. if there are further slots and respective nodes.

[0144] In the example methods illustrated in FIG. 10 to FIG. 12, each node Al to A4 has a corresponding slot TS1 to TS4 in which data from that node is placed and carried, as explained hereinafter. In other words, the slots are defined for respective nodes, thus the stored data slot allocation defines a unique data slot for each wireless device (or node) in the set of nodes shown in FIG. 5. FIG. 5 shows an example of the system 100 of FIG. 1 where "N" is 4 and "M" is 2.

[0145] When using nodewise slot allocations, each node and edge node effectively knows from which other node each incoming message has been sent originally because it is received on a data slot in the data slot allocation. The intermediate nodes can then re-transmit data from the incoming messages using the same data slot that corresponds to the node (in the set). For example, as shown in FIG. 10, each node Al to A4 has an allocated data slot TS1 to TS4, and each receiving node can act as a relay by receiving the messages, and retransmitting the same data in the outgoing message (in the same slots), e.g., as node A4 does in Round 3 of FIG. 10, thus edge node B2 (receiving from node A4) effectively knows from which node the data in each slot comes.

[0146] By the nodewise slot allocation, there is no need to determine or use network topology or to attach ID data to the messages — the data slots effectively provide an identifier for each node in the set.

[0147] By the nodewise slot allocation, the unique ID of the node can be the same as the unique data slot, e.g., there may be no need to store a further device ID in the storage.

[0148] When using the nodewise slot allocation, e.g., for a STATUS task, only 1 bit per node may be required, e.g., as shown in FIG. 11 and FIG. 12, so the round time can be correspondingly short, scaling by the number of nodes.

[0149] When using the nodewise slot allocation, at least 2 bits may be allocated to each data slot, including least 3 bits to each data slot, or at least 4 bits to each data slot

[0150] When other slot allocations, depending on the message (e.g., see Appendix A), only 1 bit may be allocated to each data slot, or at least 2 bits may be allocated, including least 3 bits to each data slot, or at least 4 bits to each data slot.

[0151] When using taskwise slot allocations, the slots are allocated to respective tasks, e.g., one or more tasks from the list in Appendix A, depending on the application, e.g., a blasting application, sensing application, or movement marker application.

[0152] When using taskwise slot allocations, the outbound and the inbound tasks can be combined when they are both treated as floods: previously, a STATUS task would be an inbound STATUS request (into the network), followed by an outbound STATUS response(s) from the nodes (to the edge of the network); however, when both are floods, there is no difference between outbound and inbound, and any data corresponding to a request could be in a slot neighbouring a response slot.

[0153] When using taskwise slot allocations for a 1 -slot concurrent protocol (where Slot 1 is the only slot), e.g., as shown in FIG. 6 to FIG. 8: a. Slot 1 may represent an alarm, e.g., a high-temperature alarm from one of the nodes transmitted in the inbound direction; or b. Slot 1 may represent a FIRE command in a blasting application, e g., a FIRE command send to the primers in the outbound direction.

[0154] When using taskwise slot allocations for a multi-slot concurrent protocol, e g , with 7 slots: a. Slot 1 may represent a SYNC command from the edge nodes, thus in the outbound direction; b. Slot 2 may represent a CALIBRATE command (including a clock rate calibration value) from the edge nodes, thus in the outbound direction; c. Slot 3 may represent an ARM command (with an ARM code) from the edge nodes, thus in the outbound direction;d. Slot 4 may represent ACK1 from Node 1 , thus in the inbound direction (transmitted by Node 1 at least in response to the SYNC and / or CALIBRATE commands); e. Slot 5 may represent ACK2 from Node 2, thus in the inbound direction (transmitted by Node 2 at least in response to the SYNC and / or CALIBRATE commands); f. Slot 6 may represent ACK3 from Node 3, thus in the inbound direction (transmitted by Node 3 at least in response to the SYNC and / or CALIBRATE commands), and g. Slot 7 may represent ACK4 from Node 4, thus in the inbound direction (transmitted by Node 4 at least in response to the SYNC and / or CALIBRATE commands)

[0155] The SYNC command can correct skew by aligning respective clocks of the nodes to a common zero time. The CALIBRATE command can correct the clock rate, as opposed to skew. The SYNC command and the CALIBRATE command could be provided in mutually different slots. For blasting applications, both the SYNC command and the CALIBRATE command may be required, and they could be provided, together, in one slot.

[0156] In another the blasting application, instead of Slot 2 representing the CALIBRATE command, Slot 2 may represent a RETIME command with a delay table

[0157] In another blasting application, instead of Slot 2 representing the CALIBRATE command, Slot 2 may represent a QUICK STATUS command with a STATUS request, and each of ACK1 to ACK 4 can represent the status, e.g., as "OKI" to "OK4". The QUICK STATUS command may be included in the system 100 when there is a poor data rate in the network, e.g., the QUICK STATUS command can be used first, and the nodes are configured to respond with OK or NOK without details, which is a low bandwidth response. Then the system 100 could query the NOK nodes (i.e., the nodes that responded NOK) for more detailed information about their status using a STATUS command.

[0158] Tn many applications, it may be preferable to perform the communications tasks in a ‘flood’ manner, using one of the arbitrary slot allocations or taskwise slot allocations, rather than nodewise slot allocations that effectively address each node individually For example, rather than addressing an individual node ID with a new delay timing, it may be preferable flood the network with the whole delay table and have the nodes look up their delay according to their ID. In another example, if the task is single hop, it may be preferable to retransmit a single longer message from multiple locations than to individually address messages at coordinated locations.Example Concurrent Methods

[0159] Described hereinafter are examples of the communication methods performed by the system 100, wherein the communication methods follow one or more TTE concurrent protocols defined by the system 100 and are referred to herein as "concurrent communication methods" or "concurrent TTE communication methods".

[0160] In the communication methods, the duration of each round is selected so that each node has sufficient time for receiving and processing before transmission is required. The size of each slot is selected based on the required data message length and the signal-to-noise (SNR) of the environment in which the system 100 is operating.

[0161] As shown in FIG. 6 to FIG. 14, the example protocols include: a. a single-round single-slot concurrent protocol — see FIG. 6 and FIG. 7; b. a multi-round single-slot concurrent protocol — see FIG. 8; c. a multi-round multi-slot concurrent protocol with time-divided concurrent data slots (also referred to as "concurrent protocol with multiple time-ordered slots") — see FIG. 9; d. a multi-round multi-slot concurrent protocol with time-divided concurrent data slots with each node sending or receiving but not both in each round — see FIG. 10;e. a multi-round multi-slot concurrent protocol with time-divided concurrent data slots, with 1 -bit data, and each node sending or receiving but not both in each round — see FIG. 11 ; f. a multi-round single-slot concurrent protocol with at least one node receiving only — see FIG. 13; and g. a multi-round multi-slot concurrent protocol with frequency- or code-divided concurrent data slots — see FIG. 14.

[0162] As shown in FIG. 6, the communication methods performed by the system 100 can include the following, according to the single-round single-slot concurrent protocol: a. an edge node Bl initiating a data message (representing any data, e g., in Appendix A — because the edge node Bl initiates the data message, it may be referred to as the “first transmitter” or "communications initiator"), transmitting that message to node Al (the dot-fdled boxes in FIG. 6 to FIG. 14 represent transmission) via the TTE link (broken line in FIG. 5); b. the node Al receiving and re-transmitting (with negligible processing delay) that data message in the same slot (time, frequency or code) to all nodes within TTE range of node Al (with negligible processing delay), which include node A2 and node A3 (connected by broken lines in FIG. 5), c. both node A2 and node A3 re-transmitting the data message (with negligible processing delay) on receipt to all nodes within their TTE ranges, thus to node A4 (from both A2 and A3) to edge node B2 (from node A3 connected by the broken line to B2 in FIG. 5), d. node A4 receiving and re-transmitting the data message (with negligible processing delay), such that all nodes and edge nodes in FIG. 5 are transmitting the data message in the one slot before the one round has finished, and e. the edge node B2 receiving the data message or processing, storage and / or transmission to the control / monitoring system 102 if required.

[0163] The term "negligible", in the context of the communication methods performed by the system 100, means the time difference of the incoming signals is negligible for the message / data detection / decoding algorithm / protocol to discern.

[0164] As shown in FIG. 7, the communication methods performed by the system 100 can include the single-round single-slot concurrent protocol with non-negligible delay at each node such that the transmission of each node or edge node starts slightly after that node hears / receives the data message because the node requires some time to receive / process the data message before it can start transmitting, e.g., to turn off the receiver Rx to mitigate damage from the node's own transmitter Tx.

[0165] The single-round single-slot concurrent protocol of FIG. 6 and FIG 7 may be referred to as a "minimal concurrent protocol", or an "instantaneous flood" or "unidirectional instantaneous flood", and may be used in some applications, e.g., to propagate a FIRE command in a blasting application with no response back required, e.g., in an outbound direction from a central controller, or outbound from one or more (potentially moving) edge nodes Bj . For the single-round single-slot concurrent protocol, there is no need for respective nodes to use non-overlapping data slots, or for the nodes to use their IDs (if they have them) because all nodes in the set can be identical (e g., in a blasting system, all firing delay times may be equal, e.g., for seismic applications, or the message flood may send a table of delays from which each node determines its delay by internal processing). The single-round singleslot concurrent protocol may be desirable for wireless blasting applications since the amount of data that needs to be transmitted is often very small (e.g., as low as 1 bit per node) and the cost of flooding the data to the whole network may be low, compared to the overhead of addressing data to particular destinations. There may be just one round and just one slot. The round does not (necessarily) repeat: the device simply re-transmits as soon as possible. There is just one slot, e g., a constant tone: nodes transmit a constant tone and wake on receipt of the constant tone, so there are no bits to process, e.g., the node may be configured to retransmit with negligible delay (before processing) and keep going for a selected amount of time, and then to turn off. In an example, if the data message comprises a simple tone with a detectable frequency (e.g., using resonant components of the node), that frequency can be used for clock rate calibration in some applications, e.g., the data message can be a CALIBRATE command, e g., for correcting the clock rate

[0166] Tn the single-round single-slot concurrent protocol of FIG 6 and FIG. 7, the nodes do not wait until the next round or slot time to retransmit, and instead start transmitting with negligible delay, or as soon as possible after their wake-up time, preferably without a processing delay. As shown in FIG. 7, each node can perform a "wake-up process", and optionally "data processing", between receiving the incoming message and transmitting the outgoing message, thus there is a non-zero, or finite, processing / wake-up time before each node starts transmitting (in its "transmitting state").

[0167] In an alternative implementation of the single-round single-slot concurrent protocol, the first transmitter (or "communications initiator") can be one of the nodes Al .. A4.

[0168] Tn the single-round single-slot concurrent protocol, each node can transmit and receive at the same time (as shown in FIG. 6).

[0169] Tn the alternative protocols described hereinafter with reference to FIG. 8 to FTG. 14, each node can transmit and receive, but not at the same time, e.g., to avoid the wireless transmitter Tx saturating / damaging the wireless receiver Rx.

[0170] As shown in FIG. 8, the communication methods performed by the system 100 can be performed according to the multi -round single-slot concurrent protocol including: a. in Round 1, an edge node Bl initiating a data message (representing any data, e.g., in Appendix A, e.g., a counter as described hereinafter — because the edge node B1 initiates the data message, it may be referred to as the “first transmitter” or "communications initiator"), transmitting that message to node Al via the TTE link (broken line in FIG. 5), and node Al listening (the empty boxes in FIG. 8 to FIG. 14 represent listening / receiving); b. in Round 2, the node Al transmitting that data message in the same slot (time, frequency or code) to all nodes within TTE range of node Al (with negligible processing delay), which include node A2 and node A3 (connected by broken lines in FIG. 5) that are listening (empty boxes in FIG. 8), c. in Round 3, both node A2 and node A3 re-transmitting the data message to all nodes within their TTE ranges, thus to node A4 and back to node Al (fromboth A2 and A3), and to edge node B2 (from node A3 connected by the broken line to B2 in FIG. 5), which are all listening (empty boxes in FIG. 8) — furthermore, edge node Bl may retransmit according to this protocol which requires each node to retransmit the received data message in the round after receiving it; d. in Round 4, each node again retransmitting the received data message in the round after receiving it, thus node A4 re-transmitting (for the first time), edge node B2 re-transmitting (for the first time), and node Al re-transmitting (for the second time), such that all nodes and edge nodes in FIG. 5 are transmitting the data message by the end of Round 4; e. in Round 5, node A3 re-transmitting the data message that includes the message from node A4 (the deepest node) for the first time; and f. in Round 6, the edge node B2 receiving the data message from node A3 (the closest node in communication with edge node B2) that for the first time includes the message from node A4 (the deepest node) — the edge node B2 can now process, store and / or transmit the data message, including input from all nodes Al .. A4, to the control / monitoring system 102 if required.

[0171] In the multi-round single-slot concurrent protocol, there is one piece of information, one slot per round, and the round repeats. The single slot floods everywhere, and each node behaves in the same way. The one slot can be a single data field representing a single command that can be interpreted or at least relayed by each node. In embodiments, the data message can have just one bit, or more than one bit of data, depending on the message type.

[0172] In the multi-round single-slot concurrent protocol, as shown in FIG. 8, the data message can include a counter C, and each node can increment the counter in each round, which means the later-receiving nodes and edge nodes can determine from the counter value how many rounds have occurred since the data message flood was initiated. The counter value can be incremented by each transmitting node, when transmitting, allowing the receiving node to determine a total time since the communications was initiated (by multiplying the counter value by the predetermined round timing TR (which can also bereferred to as the "round duration value") that is predetermined and stored in each node). In this way, the network effectively "keeps track" of the total time. In blasting applications, the total time can be used by the node to determine a firing time.

[0173] In the concurrent protocols, e.g., the method of FIG. 8, there may be repeated transmission of the same data message to any node, e.g., the edge node, and this can improve reliability (e g., if the first transmission is interrupted by noise, the second may be clearer). In FIG. 8, both nodes A2 and A4 transmit to node A4 in both ROUNDS3 and Round 5, so there are repeated TTE links and repeated rounds of transmission

[0174] In example blasting applications, the method of FIG. 8 can be used to transmit blasting commands from the surface edge nodes Bl . B2 into the network, e g , for one or more of the following commands: ARM, SYNC, FIRE, and RETIME. In the blasting applications the slot allocation can be any one of the following in each instance of the method: a. "Slot 1" represents: "FLOOD" data (e g., Blast design data or other blasting data), which is used for flooding outbound data, and SYNC is implicitly included due to the concurrent communications method; or b. "Slot 1" represents: "FIRE" data, which is transmitted in an outbound flood, and SYNC is implicitly included due to the concurrent communications method; or c. "Slot 1" represents: "ALARM" data, which is transmitted in an inbound flood initiated by a buried primer / sensor, and SYNC is implicitly included due to the concurrent communications method.

[0175] The method may be used two or more times during operation of the system 100, and each instance can be used to carry different data across the network. A number of different slot allocations could be in memory. Then a particular communications task could initiate one of them, and then a different communications task could initiate a different slot allocation. A new slot allocation for future use could also be sent out as data in a concurrent flood, and then used later in a second concurrent communications task. Alternatively, or additionally, a different communications method, e g., an TTE broadcast method, can also be used to"reprogram" the nodes so they have the matching selectable / predefmed parameters in their storages.

[0176] Tn an example, a typical method in a blasting application could include: a. loading the primers; b. one week later: using the method to gather STATUS messages; c. again, one week later: using the method to gather STATUS messages; d. during sleep (i.e., while in a SLEEP state), primers raising a high temperature ALARM (e.g. due to hot / reactive ground): using the method to send an ALARM message; e. on the day of firing: using the method to gather STATUS messages; f. then using the method to send a RETIME command; g. then using the method to send an ARM command; and h. then using the method to send a FIRE command.

[0177] In an alternative implementation of the method of FIG. 8, the first transmitter (or "communications initiator") can be one of the nodes Al .. A4, and thus provide "inbound" communications, e g., to carry a sensor alarm signal from a buried node to the surface edge nodes.

[0178] As shown in FIG. 9, the communication methods performed by the system 100 can be performed according to the multi -round multi-slot concurrent protocol with time-divided concurrent data slots. This protocol is "multi round multi slot", meaning a node, after detecting something, will not transmit right away: it will wait until the end of the round or time slot, and all collected transmissions, before deciding what to transmi t / rel ay in the next round or time slot.

[0179] As shown in FIG. 9, the multi-round multi-slot concurrent protocol can include, for example, 4 slots in each round associated with Al data (ACK1), ACK2, ACK3, ACK4 inTS 1 , TS2, TS3, TS4 respectively. As shown in FIG. 9, the time for each time slot in each round can be substantially the same, e.g., TS.

[0180] As shown in FIG. 9, the method performed in accordance with the multi-round multislot concurrent protocol includes the following: a. at initialization, in the 1N1T time slot, Bl initialises the communication by transmitting within its TTE range (see broken line in FIG. 5) to node Al, which is listening (empty box in FIG. 9) — during this slot, the transmission from Bl reaches Al (and Al only); b. Al decides to transmit in its time slot (TS1); c. in Round 1 : i. at TS1 time slot:1. Al transmits its ACK1 — this ACK1 reaches Bl, A2, and A3;2. Bl will not transmit until its next round;3 A2 has heard ACK1 and A2 will transmit its ACK2 in TS2;4. A3 has heard ACK1 and A3 will transmit its ACK3 in TS3; ii. at TS2 time slot:1. A2 transmits its ACK2, and this ACK2 reaches Al and A4;2. Al has heard ACK2, and Al will not transmit until next round;3. A4 has heard ACK2, and A4 will transmit its ACK4 in TS4; iii. at TS3 time slot:1. A3 transmits its ACK3, and this ACK3 reaches Al , A4, and B2;2. Al has heard ACK2 and ACK3, and Al will not transmit again until next round;3 A4 has heard ACK2 and ACK3, and A4 will transmit its ACK4 in TS4;4 B2 has heard ACK3, and B2 will retransmit what it detected in the next round, iv. at TS4 time slot:1. A4 transmits its ACK4, and this ACK4 reaches A3 , and A2;2. A2 has heard ACK1 and ACK4, and A2 will not transmit until next round; and3. A3 has heard ACK1 and ACK4, and A3 will not transmit again until next round.

[0181] So, by the end of Round 1, we have: a. Al heard ACK2 and ACK3, so it will transmit back ACK1 + ACK2 + ACK3 in the next round, b. A2 heard ACK 1 and ACK4, so it will transmit back ACK 1 + ACK2 + ACK4 in the next round, c. A3 heard ACK1 and ACK4, so it will transmit back ACK1 + ACK3 + ACK4 in the next round; d. A4 heard ACK2 and ACK3, so it will transmit back ACK2 + ACK3 + ACK4 in the next round; e. B 1 heard Al so it will transmit back ACK1 in the next round; and f. B2 heard ACK3 so it will transmit back ACK3 in the next round.

[0182] In Round 2, the nodes transmit as above.

[0183] After Round 2, although the combination of edge nodes Bl and B2 have together received all ACKs, each edge node B 1,B2 has not received all ACKs (of all in-ground nodes)and so it takes another round for B 1 to transmit to B2 (and vice versa) if the edge nodes are communicating with each other using the multi-round multi-slot concurrent protocol. Alternatively, the edge nodes Bl, B2 may be connected by a faster link, e g., a fast RF link, which can be substantially faster than the round timing or the slot duration of the multi-round multi-slot concurrent protocol. In most applications, it is not necessary that all surface nodes Bj receive all inbound ACKs because the surface nodes Bj can generally communicate securely and rapidly via the wired or wireless links.

[0184] In the method of FIG 9, the edge nodes send an outbound request (from Bl) and receive an inbound response (at B2 or B 1), including from the deepest nodes A2 and A4.

[0185] Tn the method of FIG 9, the data in each message (which can be a STATUS message or an ACK message) can contain multiple / many bits, e.g., the following four slots in each message, wherein the data may be blank or populated, depending on whether the message has hopped via the node corresponding to that slot: a. Slot 1 is for "ACK1" data, which can represent an inbound STATUS value or ACK value from Al for any / all edge nodes (e g., B2 etc ), and which is therefore populated by Al; b. Slot 2 is for "ACK2" data, which can represent an inbound STATUS value or ACK value from A2 for B2 etc., and which is therefore populated by A2; c. Slot 3 is for "ACK3" data, which can represent an inbound STATUS value or ACK value from A3 for B2 etc., and which is therefore populated by A3; and d. Slot 4 is for "ACK4" data, which can represent an inbound STATUS value or ACK value from A4 for B2 etc., and which is therefore populated by A4;

[0186] As shown in FIG. 10, the communication methods performed by the system 100 can be performed according to the multi-round multi-slot concurrent protocol with time-divided concurrent data slots with each node sending or receiving but not both in each round, which includes, as in FIG. 9, each node re-transmitting only after receiving for a full slot; however, in this protocol, each node only re-transmits in the next round rather than in the next available slot, so there are more slots with no transmission and more rounds until the data messagefrom the deepest node, A4, reaches the edge node B2 In a specific implementation of FIG. 10, nodes only transmit or receive during any one round, thus the first time they receive a signal, they wait until the next round to transmit; accordingly, nodes that transmit during the same round cannot communicate with each other.

[0187] As shown in FIG. 11, the communication methods performed by the system 100 can be performed according to the multi-round multi-slot concurrent protocol with time-divided concurrent data slots, with 1 -bit data, and each node sending or receiving but not both in each round, which differs from the protocol illustrated in FIG. 10 in that each data message is just 1 bit, e.g., a single tone or frequency representing 1 (or zero if it is absent).

[0188] In the method of FIG 10 and FIG. 11 , the transmission of each node contains all the status responses of every other node and itself. In the method of FIG. 11, each response is only represented by 1 bit — e.g., a carrier at frequency fO for a fixed duration AT. Each node is given a time slot TS for the flood message to describe its status — this is referred to hereinbefore as nodewise slot allocation. For example, Node A2 is assigned to time slot TS2 although its carrier frequency is still fO. If Node A2 is doing OK, it will send carrier fD at its given time slot TS2. If it is not doing OK, or if it is out of battery, there will be an absence of carrier fO at time slot TS2. Other nodes, once hearing node A2's status, will update their next transmission which include a carrier at TS2 (for example, as Node Al does at in Round3. Thanks to synchronization, the carrier frequency fO will be identical to all nodes. When a node is listening, it may hear signals coming from multiple other nodes. For example, node Al can hear nodes A2 and A3; however, one time slot (for example TS1) will not ‘smear’ to the next time slot (say TS2) thanks to the time synchronization When it comes to interference from different sources during the same time slot, there will be a phase difference between each node. However, the phase difference can be made constant for the entire TS duration of the transmission. And a sum of two sinusoids with the same carrier frequency fO, but different phases, will simply be another sinusoidal, with the same carrier frequency fO, so the node can still detect it. Even if two phases were completely opposite, the amplitudes would need to be the same to totally cancel each other. Furthermore, even if the signal is completely cancelled for one slot, there is a good chance that the next slot will have a signal, e.g., due to phase changes.

[0189] As shown in FIG. 12, the communication methods performed by the system 100 according to the multi-round multi-slot concurrent protocol with time-divided concurrent data slots, with 1 -bit data, and each node sending or receiving but not both in each round (represented in FIG. 11) can also include non-negligible processing (shown as grey blocks) at each node such that the transmission of each node or edge node starts slightly after that node hears / receives the data message because the node requires some time to process the data message before it can start transmitting. The processing delay in the other methods may be negligible because it can be negligible compared to the Tx or Rx speed (due to the wavelength of the signals taking a long time) or because the processing can be in the same time slot as the receiving.

[0190] As shown in FIG. 13, the communication methods performed by the system 100 can be performed according to the multi-round single-slot concurrent protocol with at least one node receiving only, which is the same as the methods illustrated in FIG. 8 except that one of the nodes — specifically node A4 — is configured to receive but not transmit, so A4 only has listening actions (empty boxes) and no transmitting (boxes with dots). Tn embodiments, some or all of the deeper nodes (also referred to as “deep nodes”), e g., lower deck primers in blasting applications, could be receive-only nodes to save power.

[0191] As shown in FIG. 14, the communication methods performed by the system 100 can be performed according to the multi-round multi-slot concurrent protocol with frequency- or code-divided concurrent data slots, which includes the nodes receiving and transmitting on more than one frequency / code slot in at least Round 2 and Round 3. In examples, the nonoverlapping frequency slots can be substantially 15 kHz to 70 kHz in width, e.g., 20 kHz, 25 kHz, 30 kHz, or 35 kHz wide.Experimental Examples

[0192] Example experimental results show improved performance over non-concurrent method in relation to a total duration of communications tasks

[0193] Experiments were conducted with Network Simulation 3 (NS-3). The input to the simulator was the RSS1 and locations matrices of the primers corresponding to a certain blast design as well as arguments for additional parameters such as coding method used. Theoutput of the simulator was a text-based log file of time-based operation with per-node communication, time stamps, and performance metrics. The protocol gathered the status bits from all primers across the bench for four bench sizes: 40, 100, 200 and 800 primers. Two selected concurrent protocols were compared to a prior art non-concurrent protocol (MHSSS).

[0194] The total time taken for each of the three protocols to complete the status collection task in the network is shown below.

[0195] The multi-round multi-slot concurrent protocol with time-divided concurrent data slots, with 1 -bit data, and each node sending or receiving but not both in each round required the least amount of time across the board: a. for 40 primers, the time taken was 1.45; b. for 100 primers, the time taken was 2.66; c. for 200 primers, the time taken was 8.41; and d. for 800 primers, the time taken was 61.3.

[0196] The multi-round single-slot concurrent protocol was the second best: a. for 40 primers, the time taken was 17; b. for 100 primers, the time taken was 43; c. for 200 primers, the time taken was 127; and d. for 800 primers, the time taken was 852.

[0197] The MHSSS protocol was the worst: a. for 40 primers, the time taken was 22.6; b. for 100 primers, the time taken was 63.5; c. for 200 primers, the time taken was 199; andd. for 800 primers, the time taken was 1860.Example Implementations

[0198] Implementations of the system 100 can be used in one or more of the following applications, for example as part of a commercial blasting operation: (i) commercial blasting (e.g., including using explosive primers), e.g., for mining and quarrying, seismic exploration, or avalanche blasting; (ii) monitoring movement or location (e.g., P&O, vibration) in portions of ground / earth (e.g., as ore markers) or structures (e.g., including buildings, civil engineering structures); (iii) sensing of properties of ground / earth or structures (e g., sensing temperature, moisture content, etc.); and (iv) relaying network signals between communication nodes, e g , for through-the-earth (TTE) communication

[0199] The system 100 can address limitations of previous TTE systems that had wireless devices with limited uplink range. In one or more implementations, an outbound message from an example buried node, e.g., a primer in a blasting application, can be relayed in two or more hops of concurrent communication to reach an out-of-hole receiver in an example edge node. In an example, an electronic primer in a wireless blasting system can communicate with an associated blaster or a central controller (e.g., the firing system 106) using the two or more concurrent communication hops provided by the system 100.

[0200] The system 100 can address a limitation of previous mesh networking protocols that required a lot of effort in collision detection and avoidance, e g., to prevent neighbouring network nodes from interfering with other’s transmissions, so the message overhead was large and scaled badly with the increase of the number of nodes in the network as required in many applications, e.g., blasting. The system 100 may improve communications efficiency / simplicity by avoiding overheads of previous communication systems, e.g., carrier sensing, handshaking, scheduling, and / or gathering / using network state information (neighbours, link quality, link schedulers, CSMA, routing mechanisms, etc.).

[0201] The system 100 can provide faster and / or more efficient delivery of messages from and / or to buried wireless devices (acting as the nodes) compared to previous TTE communication systems, at least for some applications, e g., sending blasting-relatedcommands to in-hole primers, or receiving status messages from in-hole primers in blasting applications.

[0202] The system 100 can provide concurrent message "flooding" (also referred to as “concurrent flooding”), in which at least one outbound message is sent into the network for receipt by all of the nodes, and / or in which at least one inbound message is sent from one of the nodes back to one of the edge nodes via potentially one or more of the nodes in the network. In concurrent flooding implementations, one or more packets of data are flooded in messages from at least one communications initiator to all other connectable nodes in the network such that they all receive identical data. In concurrent flooding implementations, the wireless device can be configured (via the stored slots and rounds) to transmit the outgoing message in at least one of same slots as the one or more slots of the incoming message. The wireless device can be configured to perform the concurrent flooding message when the incoming message is in a certain slot of the stored data slot allocation indicating that the incoming message is to be retransmitted as a flood message; and / or when a header of the incoming message indicates that the incoming message is to be retransmitted as a flood message.

[0203] In flooding implementations, multiple floods can occur at the same time, e g., from different communications initiators, by each node using a plurality of mutually different slots (of the stored slots) for a corresponding plurality of mutually different flood messages (e.g., for an inbound STATUS collection task). In these implementations, each node is configured to generate outgoing messages in two or more of the data slots by retransmitting incoming messages received in two or more respective data slots: thus enables two or more data messages to flood simultaneously across the network, potentially in mutually different directions. Alternatively, or additionally, the wireless device can be configured (via the stored slots and rounds) to transmit the outgoing message in at least one different slot from the one or more slots of the incoming message.

[0204] In flooding implementations, the protocol does not need to have any information about network topology / connectivity to transmit flood messages with a high / maximum efficiency.

[0205] Tn flooding implementations, the wireless device is configured to generate the outgoing message by retransmitting the incoming message, with the negligible delay (described hereinbefore) or a defined delay (also referred to as a “selected delay” or a “predefined delay”). The defined delay can include one or more of the following:(a) a fixed delay that all nodes incur / apply after receiving an incoming message (e.g., a flood message);(b) an adaptive delay, wherein each node, based on its own situation, assesses and adaptively calculates its individual delay that need to be incurred, e.g., based on a hop count, after receiving an incoming message so that all nodes reach to an agreed / defined time in the future; and / or(c) a delay count, e.g., representing a number of clock cycles, or a specified time duration.

[0206] The defined delay can be selected to be zero or effectively zero, and thus the defined delay can itself be a negligible delay (or “defined negligible delay”), differing from the negligible delay mentioned hereinbefore in that it is defined as a value equivalent to zero or substantially zero, whereas the negligible delay can be effected without having a time value selected / defined.

[0207] The nodes may each be configured to retransmit after a negligible delay, or zero delay (transmit immediately after receive), when all nodes have substantially mutually the same response time to respective incoming messages, so all those nodes will transmit at the same time, in each round. Having a substantial zero or negligible response time can allow for rapid concurrent transmission multihop communications.

[0208] Similarly, the nodes may each be configured to retransmit after the fixed delay when all nodes have substantially mutually the same response time to respective incoming messages, so all those nodes will transmit at the same time in each round.

[0209] In contrast, the nodes may each be configured to retransmit after the adaptive delay when the communicating nodes have mutually unequal response times to incoming messages: in these circumstances, the adaptive delay effectively accounts for, or corrects for, differencesin response times to incoming messages between the nodes. Tn other words, the receiving nodes may be slightly offset from each other in time response to an incoming message because each receiver takes a mutually different time to receive / process the incoming message: if the times when the receivers in the nodes complete receiving the incoming message is not consistent, the adaptive delay operates to substantially correct all nodes to still transmit at substantially the same time, thus retaining concurrent transmission from all nodes in the network.

[0210] FIG. 6 and FIG 7 show examples of the nodes retransmitting the incoming message substantially immediately after a zero or negligible delay. FIG. 6 could be considered to represent retransmitting the incoming message substantially immediately after a zero delay, or a defined delay of zero. FIG. 7 could be considered to represent retransmitting the incoming message substantially immediately after a negligible delay, or a defined negligible delay.

[0211] This concurrent message flooding can be used to efficiently send a broadcast message to all nodes by way of the multihop network, thus not necessarily requiring a separate TTE broadcast system as in prior art TTE communication systems, which may make communicating efficiently with very large numbers of nodes more effective. Tn blasting applications, the broadcast message may include a STATUS message and / or a SYNC message. In embodiments, the concurrent message flooding can have very low latency.

[0212] The concurrent message flooding implementations may require only a simple selectable / predefined slot allocation, e g., just one slot for the set of nodes, if the same message is being sent to all nodes.

[0213] In contrast to the flooding implementations, information about network topology / connectivity can be used to route information on a particular path or in a particular subset of the network, still using the concurrent protocol(s) disclosed herein, although with network topology / connectivity in the messages, e g., node IDs in the messages. These implementations may be referred to as “concurrent routing” as opposed to “concurrent flooding”. In routing implementations, each node can be configured to recognise a node identifier (ID) in the incoming message in order to decide whether to generate the outgoing message, what data to include in the outgoing message, or to remain silent. By recognising anode ID in the incoming message, the node can decide to not transmit an outgoing message if the node knows that the incoming the node ID corresponds to a node that is not part of the current network or subnetwork, and this saves power by not transmitting unnecessary outgoing messages. The node can know whether the incoming node ID corresponds to the current network or subnetwork based on stored node IDs in the node, e.g., stored / written in the storage by being (a) hardcoded into the node, (b) encoded by an encoding machine, or (c) sent via a TTE wireless message over the network (these are potentially the same methods of providing the slot allocation and the round timing to the node).

[0214] Requirements for security of the communications may be relaxed due to the relatively short range of the TTE links (dashed lines in FIG. 1), and availability of additional information, such as localization of the nodes (e.g., using techniques described in International Patent Application No. PCT / SG2025 / 050084 and / or International Patent Application No. PCT / SG2023 / 050551).

[0215] For blasting applications, the node must know its firing delay. The node must also have a clock, counting time. Preferably the node also has a clock rate calibration (recorded / calculated calibration factors). These items need not necessarily be in non-volatile memory. Optionally, only the node ID, or only a frequency assignment, is needed at encoding time and placement time, and the delay time can be provided by the incoming message. Sometimes in mining, very long boreholes are used for blasting. For example, in open cut mining, benches can have 80 m deep holes (although this is exceptional). In underground mining, block cave preconditioning holes or drop raises can also be very long (more than one hundred metres, for instance, hundreds of metres). In the system 100, a shallower primer could act as a ‘relay’ for a deeper one. By using this multi-hop architecture, the effective depth range of the wireless blasting system can be improved or extended. There may be several primers in long holes, at intervals of about 15 m. As a representative example, such a concept can be applied to examining a group of up to 16 primers in a straight line. Examples include: two primers (extended range open cut, common practice double-priming), eight primers (deep open cut), and sixteen primers (very long underground holes). In ground types that are favourable for wireless blasting, primers that are ‘second neighbours' may also be detectable to each other depending on the primer separation (with an 18 dB signal difference). There may also be neighbouring holes with primers in them. The holes wouldtypically be managed as separate subnetworks although they would be within signal range of each other. The primers can be configured for algorithmic retiming, which is retiming (programming new blast delay times) wherein the node can calculate its delay time based on its position or look it up in a delay table based on its node ID. This allows for the algorithm or delay table to be flooded to the whole network, which may be preferrable to routing individual delay time data to different nodes. The message may include a message type, e g., one of the message / command types in Appendix A. In some applications, the STATUS request may be used in two tasks as described hereinbefore: a quick status which may be answered with one bit of information; and a long status which may be answered using a list of possible error codes or battery / SNR level codes.

[0216] The system 100 can be configured to provide environmental sensing, such as temperature sensing and / or a temperature alarm. In some kinds of mining, ground can be very hot, or reactive with the blasting agent, or both. In these cases, special inhibitor ingredients and temperature monitoring are used. The system 100 can be configured to raise an alarm in the event of the measured temperature rising above a predetermined threshold. Therefore, it is not suited to an architecture with a moving surface radio (person or drone), unless at least one moving surface radio returns to a common, known, or predetermined location or position on a regular, recurrent, or periodic basis. This system could have a single, static edge node, e.g., a surface radio, and the underground primers would utilise multihop communications to report a temperature condition or raise the alarm.

[0217] The system 100 can be configured to provide more resilient TTE communications, e g., as used in mine communications MI radio, or "induction radio" is used in cave communications and prior-art mine communications systems. It is possible to send and receive voice and text message information to people underground. Induction radio has previously been investigated as a possible emergency communication system for coal mining, that would be resilient towards explosions and collapses underground. The relay nodes could be buried within the tunnel walls and be able to provide a peer-to-peer (P2P) network in the event of an emergency.

[0218] The system 100 can be used with the systems described in International Patent Application No. PCT / AU2013 / 001171, "Locating underground markers", and / or described inInternational Patent Application No. PCT / SG2020 / 050370, for movement monitoring and localizing remote / buried objects.

[0219] Examples of the system 100 may be used for TTE communication in one or more of the following operations / applications (also described in International Patent Application No. PCT / SG2025 / 050084): a. block caving: caved extent, movement of caved material; b. geotechnical monitoring (measuring pore pressure, inclination changes etc.) for slope stability, tailings dams, water reservoirs, leach heaps stability (at mines), and / or stockpile stability; c. checking wireless primer locations for commercial blasting applications, surface, underground (U / G), seismic, civil, including ensuring the wireless primers are in safe locations, not moved, including checking for slumping / floating / missing primers; d. encoding wireless primers (with their delay times) in the rock according to detected position and a blast design; e. coal stockpile and landfill temperature and temperature gradient monitoring (for spontaneous combustion); f. in surface mining, measurement of borehole toe position and water level depending on the density of the node, g. in underground mining, wherein the as-drilled borehole location in underground mining to be used when designing a shot, such as with continuous density control when loading emulsion explosives (e g., ORICA's "4D"); h. marking underground utilities, especially long ones with many markers, e.g., pipelines, including with markers configured for leak detection; i. monitoring explosives in hot and / or reactive ground;j. tracking ore / waste to stockpiles, conveyors, dumps, crushers, e g., similar to ORICA's ORETrack; k. locating snow (avalanche) monitoring sensors to measure snow thickness, stresses inclination changes etc.; l. detecting or tracking drill bits, or portions of drill bits or drill strings, used to drill rock / boreholes, including during drilling and / or if portions break off, i.e., become detached in the ground / rock; m. measuring draw within coarse ore stockpiles (internal movement trajectories) for the purposes of tracking grade / hardness / fragmentation information within the stockpile, e.g., when material is added on the top from the crusher and drawn out from beneath; n. tracking locations of objects during or after demolition blasting by securing / attaching the node thereto, e.g., metals intended for recycling, or hazardous objects that cannot be removed from the structure prior to blasting; and o. near-surface soil monitoring for agriculture, e g., using devices configured to monitor moisture etc in the soil, e g., devices including the nodes that are tolerant to ploughing, and / or detecting their positions while wirelessly gathering the sensed soil monitoring data.

[0220] In ore tracking operations, as described hereinbefore, the system 100 may include the nodes buried adjacent to or in an ore body (e.g., down a borehole), and the methods may include tracking the ore body during blasting, excavation and / or processing by the localization of the corresponding nodes. The methods may include measuring draw of a stockpile by repeated localization of the corresponding nodes over a selected time period.

[0221] In commercial blasting operations, the system 100 may include at least one node that includes or forms a blast initiation device or blast primer device for initiating blasts, and the methods may include localizing the blast initiation device or the blast primer device based onthe localization of at least one node that includes or forms the blast initiation device or the blast primer device.

[0222] Tn drilling operations, the system 100 may include at least one node substantially adjacent to, coupled to or incorporated into a drill bit or a drill string. The methods may include localizing at least a portion of the drill bit or drill string by localizing the corresponding node during drilling with the drill bit or drill string (e.g., in the opaque medium 108), or after detachment of the portion from the drill bit or drill string (e.g., in a muck pile). The detecting or tracking of the drill bits may including detecting tracking "drill steel", including drill bits lost in the rock / earth during drilling of boreholes. The process may include loading a borehole with both the node and the drill steel, including loading the node into the borehole that contains a portion of drill steel lost in the borehole. The process can include marking / recording that node — the "drill node" — as tracking or corresponding to the lost drill steel, e g., using the marker's code or ID; alternatively, the drill bit marker may be the only marker used in the shot, so ID may not be required, to distinguish it from ore markers / primers etc. The process can then include the localization of the drill node, and hence substantial localization of the drill steel, including before blasting, after blasting, during excavation of the muck pile, and during processing of the excavated material. Localization and monitoring / tracking of drill steel in the mine / quarry site and material processing can be critical to mitigate lost drill steel damaging processing equipment, especially in sites where the rock is hard, so the drill steel is very hard and thus harder than the material being processed. By provision and tracking of the drill node, the position of the lost drill steel is provided to survey / fleet management systems, e.g., software controlling excavation, and a selected volume of the material around the lost drill location is dug out and sent to waste, or the drill steel recovered and removed in a separate processing / excavation step. More than one marker may be deployed with the drill bit, for the sake of redundancy / reliability. The bit may be bonded to the marker, e.g., using resin / grout, to increase the likelihood of the bit being close to the marker after the shot. In addition to a survey / FMS system, an augmented reality system could be used by a spotter to help guide a person operating an excavator.

[0223] In seismic operations, including transition zone seismic blasting, the system 100 may include the nodes respectively incorporated into or attached to seismic receivers(hydrophones / geophones) and / or seismic sources (blasting devices, which may also include nodes). The methods may include localizing the seismic receivers and / or the seismic sources localizing the nodes incorporated therein or attached thereto. The seismic sources may include quasi-planar shock wave generators, including as described in International Patent Application No. PCT / SG2020 / 050371.

[0224] The seismic receivers and the seismic sources can be synchronised to the same time base using the TTE communications in the same way as wireless primer delays are synchronised, e g., in ORICA's WEBGEN system, and / or as described in International Patent Application No. PCT / SG2020 / 050370.

[0225] In avalanche blasting operations, the process for drone-based avalanche blasting may be similar to the seismic blasting process, including using receivers with the node for detecting whether the avalanche has been successfully triggered, and including locating primers with the node where an avalanche has occurred after deployment of the primers but before their firing.

[0226] In leach mining operations, the system 100 may include the nodes placed on or buried in the opaque medium 108 in the form of broken rock (e.g., in a heap). The methods may include: placing / burying the node in the broken rock; and subsequently monitoring movement of the broken rock by repeatedly localizing the node buried in the broken rock. The system 100 can include sensor devices or blast initiator / primer devices, each incorporating one of the nodes, deployed in the leach heap, and the methods can include localizing the sensor devices or the blast initiator / primer devices by localizing the or each corresponding node. These nodes need not be deployed in holes: they could be added to the rock at a prior stage of the mining process before heaping (or stacking) the heap, e.g., to an un-blasted bench, in a conveyor, in a truck, and / or to ore before processing (Run Of Mine). The process may include re-localizing these nodes when the heap is "re-stacked", which includes digging and re-building a heap to reinvigorate flow of the lixiviant. The 3D locations of the nodes (thus of the sensors / primers) may be useful for in-place recovery, "in- place leaching" (IPL), or "stope leaching", because the stope can settle when material is drawn from the bottom or over time. The methods may include measuring the positions ofnodes buried under an impermeable liner beneath a leach heap, e g., for the purpose of detecting leaks through a liner.

[0227] Tn dig limiting operations, the system 100 may include at least one node buried in a selected location in the opaque medium 108 relative to and / or adjacent to and / or above explosive material, generally in an explosive column with a blast initiation device or blast primer device for initiating the explosive material: the node thus marks the location of the explosive material for safety reasons. The methods may include placing the node at or near the top of the explosive column, or at least above the explosive material, e g., in the stemming. The methods may include localizing the explosive material in the opaque medium 108 by localizing the node buried at the selected location in the opaque medium 108 relative to and / or adjacent to and / or above the explosive material, which may be while digging / excavating a portion of the opaque medium 108, or in a survey process (e.g., using a drone) after a portion has been excavated. The node may be incorporated into a blast initiator / primer device. In this application, the marker marks the actual top-of-charge position The detected 3D location of the marker can be compared to the topography of the ground surface, e.g., from drone photogrammetry, and used to ensure that there is adequate cover over the explosives after digging / excavation and prior to blasting of the marked explosive column (to mitigate the risk of wild flyrock etc.), e.g., used by the shotfirer in their safety checks. The dig limiting application may be relevant where wireless blasting is used with buried shots because the shot remains buried while shots above are blasted and dug away, or a haul road operates above, and there may be uncertainty as to how much has been dug away.

[0228] In utility marking operations, the system 100 may include at least one node buried in a selected location in the opaque medium 108 relative to and / or adjacent to and / or above a buried utility, such as a linear utility (e.g., a pipeline / powerline) in the opaque medium 108. The methods may include placing the node in the selected location, e.g., in a trench with the buried or linear utility. The methods may include localizing buried or linear utility in the opaque medium 108 by localizing the node buried in the selected location (i.e., in the opaque medium 108 relative to and / or adjacent to and / or above the buried or linear utility), optionally while digging / excavating a portion of the opaque medium 108 above the buried or linear utility.

[0229] Tn soil monitoring operations, the node can include one or more environmental sensors configured to detect, monitor, estimate, or measure physical parameters of the surrounding portion of the opaque medium 108, and the one or more environmental sensors may include temperature sensors, moisture sensors, and / or chemical and / or biological substance or species sensors (e.g., for soil monitoring). The shell may be configured by its size / resilience to be tolerant to ploughing / erosion (in a way that wired soil sensors, connected by wires to a central hub or an above-ground unit, would not be), mitigating the need to remove the nodes from the soil / paddock / pasture, and allowing for the new position of the sensor to be measured if it moves due to ploughing / erosion. The methods may include localizing measured physical parameters of the opaque medium 108, e.g., pressure, moisture, and / or temperature, by localizing at least one node buried in the opaque medium 108 with respective environmental sensors to measure the physical parameter values, optionally while ploughing the opaque medium 108 adjacent / around the buried node.

[0230] In mine rescue operations, the nodes can form or be incorporated into tracking / communications beacons for trapped miners The system may include fixed nodes that are embedded in tunnel walls / roofs, e.g., provided by the mine to generate a resilient peer-to-peer wireless network in case of emergencies. The nodes may be incorporated marker magnetic sensors that are incorporated in existing cap lamps / batteries, respirator / self- rescue devices, or sewn into clothing.

[0231] In avalanche rescue operations, or in civil engineering operations, the nodes may be incorporated into rescue devices for mountain workers or engineering workers, e.g., attached or incorporated in clothing, modified ski passes / access tags, and / or smartphone cases / power banks. The methods may include localizing a person or a piece of equipment buried in the opaque medium 108, e.g., an avalanche, a landslide, or a (collapsed) structure, by localizing at least one node attached to the person or the piece of equipment in the opaque medium 108.

[0232] In geological, seismological or construction monitoring operations, the methods may include placing / burying node on / in the opaque medium 108 (rock, earth, foundations or structures), and the methods may include localizing the node repeatedly over a selected time period to monitor movement of the opaque medium 108, e g., up to months, years or decades, depending on the battery life of the node.

[0233] Tn drone-based operations, one of the edge nodes on / in a vehicle may include a mobile TTE source and a wireless TTE receiver to gather data from devices incorporating the nodes allowing localization of the nodes in the same flight path / travel pattern used to gather the relevant data. Furthermore, the process of generating the TTE signals may be combined with another task performed by a drone, e.g., optical / thermal camera monitoring.Missing Nodes

[0234] In some implementations, one or more of the nodes may be deployed but fail to connected / communicate with the cluster / network — these nodes, deployed but not in communication, are referred to as "missing nodes" herein. A deployed node may become a missing node because of an internal failure, e.g., an electronic internal failure or a battery failure. Alternatively, a deployed node may become a missing node because it is too distant from the adjacent nodes to have reliably TTE communication, including distance through the earth, and increased magnetic distance caused by high-reluctance materials / rock in the earth. Alternatively, a deployed node may become a missing node because it is moved away from its intended locations, e g , unintentionally (due to a magazine or deployment failure) or intentionally (due to theft).

[0235] To address the problems of missing nodes, the system 100 may perform the following method: a. determining, from a set of wireless devices, each configured for through-the- earth (TTE) communication to form a cluster or network in a site, a unique node identifier (ID) of each wireless device in the cluster or network (e.g., by receiving a STATUS data message from the wireless devices that includes the device's node ID); b. determining, from a control system that is external to the set of wireless devices, a set of device identifiers (IDs) of wireless devices deployed in the site (e g , a set of primer IDs in deployed blast, optionally determined from an encoder or a blast plan, or a set of device IDs in another application);c. comparing the unique node IDs to the set of device IDs to determine that one or more of the deployed wireless devices is not in reliable communication with the cluster or network (and are thus "missing nodes"); and deploying a further wireless device to the set of wireless devices at a location in the site selected to improve the reliability of the communication with the determined one or more of the deployed wireless devices, or broadcasting a DISABLE command to the site to disable the determined one or more of the deployed wireless devices that are not in reliable communication with the cluster or network.

[0236] The missing nodes may be completely undetected in the network, and thus not being in reliable communication can include not being in communication. Alternatively, the missing nodes may be in unreliable communication defined by a threshold that can be based on signal strength (e.g., magnetic field strength or signal-to-noise ratio of received data messages, or a Received Signal Strength Indicator, RSSI) and / or statistics (e.g., numbers of messages received from the deployed wireless devices as a fraction of messages received from the other nodes). The statistics threshold can be over 99.99% for high reliability applications, e.g., blasting, or over 99%, or over 90% or over 60% for less reliable applications, e.g., movement monitoring. The signal strength of signals from potentially missing nodes may be measured in each node in the cluster / network, and transmitted in data messages to the control / monitoring system 102, as described hereinbefore, and any signal strength below the selected threshold identifies a missing node. The connection statistics from potentially missing nodes may be determined in data from data messages provided to the control / monitoring system 102, e.g., the control / monitoring system 102 may receive a selected number X of status messages, and if any nodes return fewer than the statistics threshold, they are determined to be missing nodes. Collection of the statistics / signal strengths is efficient because the nodes may have limited stored power on board.

[0237] The further wireless device typically includes at least one edge node, optionally configured for non-TTE communications. The edge nodes may be easier / cheaper to deploy than the buryable nodes, at least because they can be moved over the surface / along a tunnel,and because they can connect rapidly to the control / monitoring system 102 via the non-TTE communications links.

[0238] The method may include selecting the location for the further wireless device: a. by placing the further wireless device in the site at one or more locations, testing the reliability of the communication of the determined one or more of the deployed wireless devices with the further wireless device at a plurality of test locations in the site, and selecting the test location with the highest tested reliability at the selected location; and / or b. using a deployment map for the set of wireless devices, e.g., a blast plan, to determine where the missing nodes are intended to be deployed, and placing the further wireless device within TTE communication range of those intended deployment locations;

[0239] Deploying the further wireless device may include: a. carrying the further wireless device on a vehicle to the selected location; b. testing the reliability of the communication of the determined one or more of the deployed wireless devices with the further wireless device at the selected location (optionally whilst the vehicle is moving and generating substantial MI noise, or whilst the vehicle is parked and in a SLEEP mode that does not generate substantial MI noise); and c. deploying the further wireless device from the vehicle at the selected location, e.g., using a deployment arm or mechanism.

[0240] If the missing node cannot be found, it may be dangerous, e.g., if the node includes a primer, so it may be desirable to deactivate the missing nodes. Accordingly, the method may include controlling one or more wireless transmitter systems to broadcast the wireless DISABLE command to disable wireless devices with the missing IDs, wherein each DISABLE command includes one of the missing IDs. The system 100 may include a wireless transmitter system configured to send a broadcast TTE signal including the DISABLE command as described in International Patent Application No. PCT / SG2022 / 050603. In ablasting application, if a primer is not communicating in the cluster / network, then the primer is not loaded or it is in the hole and not operating properly, and in both cases such a primer should be disabled for safety reasons. The DISABLE command may be referred to as a “universal disabling signal”. The wireless transmitter system may include commercially available transmitters and wireless transmitter antennas, including respective signal generators (which may be configured to deliver relatively high current / power depending on the antennas and the sizes of the deactivation zones) configured to receive a command for the wireless device, and configured to drive one or more wireless transmitter antennas (RF antennas or MI antennas) to transmit the command in a wireless signal (electromagnetic or quasi-static) to the wireless device at specific frequencies for which the wireless devices are configured. For example, the wireless transmitter system may include a high-current signal generator in the form of a WEBGEN(TM) fire system transmitter and an MI antenna in the form of a WEBGEN(TM) antenna that generates the high power MI signal. The coverage of the wireless signal (RF or MI) is controlled by orientation, position, configuration and power (e g., based on the drive current) of the wireless transmitter antenna. The transmitter antennas may include a coil of conductive wire including one or more loops, with smaller loops (e.g., substantially 0.5 m to 1.5 m in diameter, e g., substantially 1 m in diameter) for short range transmission, and larger loops (e.g., substantially 5 m to 80 m in diameter, or substantially 20 m to 60 m in diameter, e.g., substantially 40 m in diameter) for longer range transmission. The range of the transmitter antennas can be substantially 5 m to 80 m in diameter, 10 m to 25 m, e.g., substantially 5 m to 80 m in diameter, 15 m. At least the MI transmitter can transmit the disable signals through walls and through the earth (TTE), and in some implementations, into the interior of vehicles and storage boxes / magazines for the missing wireless devices in the site. A deactivation zone is generally along the principal axis of the Ml antenna, so the MI antennas are arranged with principal axes directed to and through various predefined deactivation zones. Each MI antenna may define a deactivation zone generally along the principal axis and with a cross-section defined by the coil size. The wireless transmitter systems may include a plurality of the RF and / or MI antennas (depending in whether the wireless devices are configured to receive RF and / or MI), including: a plurality of the antennas defining one deactivation zone (e.g., having non-overlapping principal axes); and a plurality of deactivation zones, each with one or more antennas.

[0241] As described hereinbefore, each wireless device, including the missing nodes, includes: a. a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one other wireless device in the set of wireless devices; b. a wireless transmitter (Tx) configured to transmit TTE signals representing an outgoing message to at least one other wireless device in the set of wireless devices; and c. a selectable / predefmed data slot allocation and a selectable / predefined round timing that define one or more rounds of concurrent communications,

[0242] Each wireless device is configured to interpret the incoming message based on the incoming message (or properties of the incoming message) compared to the selectable / predefined data slot allocation, and transmit the outgoing message according to the selectable / predefined data slot allocation and the selectable / predefined round timing, such that each wireless device can communicate concurrently with the other wireless devices in the set of wireless devices.MI Signals and Interpretation

[0243] "Through the earth" (TTE) includes or refers to the communication of signals in, through and / or across a set of physical media residing between the signal source and the signal receiver or detector, e.g., wherein at least one of the signal source and the signal detector is at least partially obstructed, overlaid, covered, surrounded, buried, enclosed, or encased by the set of physical media. The set of physical media can include one or more of rock, broken rock, stone, rubble, debris, gravel, cement, concrete, stemming material, soil, dirt, sand, clay, mud, sediment, snow, ice, one or more hydrocarbon fuel reservoirs, site infrastructure, building / construction materials, and / or other media or materials. The physical media can be referred to as "the earth", where "earth" includes the ground, soil, a rock formation, rock, construction material / concrete, stone, borehole stemming, ice, frozen ground, etc.

[0244] Depending on the application, the nodes may be surrounded / buried in boreholes in hard material, or in piles of loose material: in the loose material, there may be fewer size constraints on the node, so the protective housing and the marker antenna could be long, perhaps one metre or more. If node survivability is not required, e.g. for a seismic primer in a borehole, the protective housing and the marker antenna could also potentially be one metre or more.

[0245] In use, when the TTE signals are MI signals, the node is located within a near-field region or zone of the magnetic field generated by the nearest neighbour node. The magnetic field strength decays as a function of distance, including in accordance with an inverse distance cubed relationship, and the node detects changes in near-field magnetic flux generated by the MI transmitter Tx component rather than detecting far-field or radiatively propagated electromagnetic waves (e.g., "radio" waves) generated by the Ml transmitter Tx component. Alternatively / additionally, the node may be located within the transition region or zone (between the near-field and the far-field) of the magnetic field generated by the nearest neighbour node.

[0246] When the TTE signals are MI signals, the wireless receiver (Rx) includes at least one magnetometer, and the wireless transmitter (Tx) includes at least one magnetic field source. For detecting the modulated magnetic field (b) of the MI signals, the magnetometer may be positioned, during operation, in or beyond the near-field region or zone of the magnetic field source , e.g., within approximately one-half of a wavelength away from the nearest neighbour magnetic field source, and more commonly or particularly resides within approximately 10 skin depths (e g., less than 10 skin depths), approximately 6 to 8 skin depths (e g., less than 8 skin depths), approximately 3 to 5 skin depths (e.g., less than 5 skin depths), or approximately 2 to 4 skin depths (e g., less than 4 skin depths) away from the magnetic field source. Additionally / altematively, the magnetometer may be positioned, during operation, at any distance from the magnetic field source while the signal-to-noise ratio (SNR) detected by the magnetometer is above a selected threshold (minimum SNR threshold or minimum magnetic field threshold), e.g., a selected threshold for amplitude / phase / frequency recovery.

[0247] The modulated magnetic fields (b) of the MI signals may travel a distance TTE that is defined by the magnetic field detection range of the magnetometer and external noise(including atmospheric and man-made noise) that defines the SNR. The distance can be less than 200 meters ("m"); less than 100 m; less than 80 m; less than 60 m; between 0. 10 m and 60 m; between 0.25 m and 50 m; between 0.50 m and 40 m; or between 1 and 30 m.

[0248] The carrier frequency (fc) of the MI signals can include at least one frequency in the low frequency (LF) ITU frequency band, and / or frequencies that include substantially 1.8 kHz, or between 1 kHz and 2 kHz, or between 1 kHz and 5 kHz, or between 1 kHz and 10 kHz, or between 100 Hz and 10 kHz, or between 0. 1 kHz and 200 kHz, or between 10 kHz and 50 kHz, or between 50 kHz and 100 kHz, or between 100 Hz and 100 kHz, or between 100 kHz and 200 kHz, or between 120 kHz and 130 kHz, optionally at least 1 kHz and no more than 50 kHz, optionally no more than 40 kHz, optionally no more than 30 kHz, optionally no more than 20 kHz, optionally no more than 10 kHz, and / or optionally no more than 5 kHz.

[0249] In some embodiments, the node may receive downlink / broadcast signals from a large antenna (e.g., a 'WEBGEN' antenna), including MI broadcast signals, in addition to the concurrent communication messages. These downlink signals can travel a downlink distance (including TTE) using one or more downlink MI signal frequencies, which can include broadcast MI signal frequencies. The broadcast MI signal frequencies, e g., from a large 'WEBGEN' antenna, can include substantially 1.8 kHz, or between 1 kHz and 2 kHz, or between 1 kHz and 5 kHz, or between 1 kHz and 10 kHz, or between 100 Hz and 10 kHz, or between 0. 1 kHz and 200 kHz, or between 10 kHz and 50 kHz, or between 50 kHz and 100 kHz, or between 100 Hz and 100 kHz, or between 100 kHz and 200 kHz, or between 120 kHz and 130 kHz, and the downlink distance can be greater than 100 meters; greater than multiple or many hundreds of meters, between 200 and 900 meters; greater than a kilometre, or greater than multiple kilometres. The broadcast downlink MI signal frequencies can include at least one frequency within the ultra-low frequency (ULF) band, or within the very low frequency (VLF) band as defined by the International Telecommunications Union (ITU). The MI downlink signals from the wireless MI transmitter component (116) would typically be of lower power than from a large 'WEBGEN' antenna, and would have less range, as described hereinbefore under the heading 'Downlink Signals'.

[0250] As used herein, the term “set” corresponds to or is defined as a non-empty finite organization of elements that mathematically exhibits a cardinality of at least 1 (i.e., a set as defined herein can correspond to a unit, singlet, or single element set, or a multiple element set), in accordance with known mathematical definitions (for instance, in a manner corresponding to that described in An Introduction to Mathematical Reasoning: Numbers, Sets, and Functions , “Chapter 11 : Properties of Finite Sets” (e g , as indicated on p. 140), by Peter J. Eccles, Cambridge University Press (1998)). Thus, a set includes at least one element. In general, an element of a set can include or be one or more portions of a system, an apparatus, a device, a structure, an object, a process, a procedure, physical parameter, or a value depending upon the type of set under consideration.

[0251] The FIGs. included herewith show aspects of non-limiting representative embodiments in accordance with the present disclosure, and particular structural elements shown in the FIGs. may not be shown to scale or precisely to scale relative to each other. The depiction of a given element or consideration or use of a particular element number in a particular FIG. or a reference thereto in corresponding descriptive material can encompass the same, an equivalent, an analogous, categorically analogous, or similar element or element number identified in another FIG. or descriptive material associated therewith The presence in a FIG. or text herein is understood to mean “and / or”, i.e., “X / Y” is to mean “X” or “Y” or “both X and Y”, unless otherwise indicated. The recitation of a particular numerical value or value range herein is understood to include or be a recitation of an approximate numerical value or value range, for instance, within + / - 20%, + / - 15%, + / - 10%, + / - 5%, + / - 2.5%, + / - 2%, + / - 1%, + / - 0.5%, or + / - 0%. The term “essentially all” or “substantially” can indicate a percentage greater than or equal to 50%, 60%, 70%, 80%, or 90%, for instance, 92.5%, 95%, 97.5%, 99%, or 100%.

[0252] The term "negligible" indicates a value substantially less than the comparison value, e.g., a value that is less than 10%, 5%, 1%, or 0.1% of the comparison value. The term "non- negligible" indicates a value substantially equal to the comparison value, e.g., a value that is less more than 1%, 5%, 10%, or 50% of the comparison value.

[0253] Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

[0254] Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0255] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.Error Detection and Correction

[0256] In some embodiments, the data message includes one or more bits that the nodes are configured to use for at least error detection, or for error detection and error correction. The data messages typically include a known error-detection code, e.g., a Cyclic Redundancy Check (CRC), and the nodes are configured to detect errors using known algorithms, e.g., the CRC algorithm.Hop Count

[0257] In some embodiments, generates the outgoing message based on, and including, a hop count determined from a hop court of the incoming message plus 1.

[0258] The hop count represents how many hops have been made in the network since the communication was initiated, e.g., since the flood was initiated. This hop count may be referred to as the “global hop count” and can be used to determine / trace the original transmission time of the communication since, in general, each hop has a duration that is preset or determined by the time window of the corresponding round. Thus, the time since a flood was initiated can be equal to the (global) hop count multiplied by the hop duration (e g., the round timing window / duration).

[0259] Determining the total hop count, and thus the time since a communication was initiated, can be important when synchronizing the nodes in the network, and this can be essential for certain commercial blasting applications.

[0260] The total hop count may be used as a measure of network quality: e g., if the total hop count determined at an exit node changes without the node topology changing, that may indicate a change in the TTE transmissibility between nodes and / or an error in one of the nodes.Retransmission Count

[0261] The wireless device may be configured to only transmit an outgoing signal once, or a selected / set number of times (which can be referred to as the “repeat transmission times”). In this case, the wireless device counts each time a message is transmitted (to determine a retransmission count), and stops retransmitting that message when the retransmission count reaches the repeat transmission times. This can be essential to stop the nodes endlessly retransmitting a message until their power runs out, and thus potentially blocking transmission of a new message.Further Experimental Examples

[0262] In an experimental example, a wireless communications testbed had 16 example vertical boreholes in a substantially flat field of earth / rock, and an example of the wireless devices disclosed herein (each referred to as a “testbed node”) was buried in each borehole. Each borehole was substantially 8 meters deep, and the boreholes formed a substantially rectangular array, as shown in FIG. 15, with a spacing of substantially 6 meters between adjacent rows and columns of downholes. As such, the testbed was intended to model the physical conditions of wireless primers deployed in a mining blast.

[0263] In the experimental example, repeated experiments were conducted (e g., up to 100 runs each time) in order to collect statistical data on the network’s synchronisation, message latency, and bit error rate; for each experiment, these data were collected by a data acquisition unit DAQ 1602, located above ground, which communicated with the testbed nodes 1604 via instrumentation links 1606 as shown in FIG. 16. A personal computer (PC) of the DAQ 1602 commanded a network node 1604 in the testbed to initiate MI communication. Each time a node 1604 heard an MI message, it reported back to the DAQ 1602 over the instrumentation link 1606. The time of each event was recorded by the DAQ 1602, and saved in a result log fde. The nodes 1604 in the network also a countdown timer triggeredthe first time they heard the MT message. This timer models the final countdown stage of an electronic detonator in a wireless blast. The countdown duration was adjusted at each node 1604 to take into account how much time (and thus how many hops) the MT message had been relayed / circulated in the network. Ideally, all the nodes in the network would have reached their detonation countdown timeout at the same time, thus ideally all nodes in the network would have been synchronized to the same time base This models the synchronisation requirement in wireless blasting, for the purpose of programmed blast delays. The log files were analysed for statistics on the network’s synchronisation performance. Log file time event data was grouped by hop count. The statistical distribution of the time data within each hop gave information on the synchronisation performance at each hop. As the size of a network increases, so does the number of hops required to achieve network coverage. Thus, the synchronisation statistics as a function of hop count indicate the scalability of the concurrent communications method for a blasting product.

[0264] Each testbed node 1604 comprised a 2Way Module (2WM), and a Daughter Board (DB). In the 2WM, there was a commercially available wireless receiver chip (WRC) that issues a START interrupt (GPIO toggle) to the 2WM. There was also a DATA line from the WRC to tell the 2WM what message the WRC had received. A typical message through MI comms (through the ground) consisted of a WRC header (so that the WRC would produce a start signal upon receiving that), and a payload comprising a message ID (a command or some other data), hop count, and CRC for error detection.

[0265] Due to the extremely limited bitrate of the underlying MI physical layer, additional data framing was kept as small as possible The experimental messages generally included a header with at least a portion used as a prefix, e.g., with flags to indicate what type of flood message being transmitted, a relay counter, and a flood ID etc

[0266] An example experimental message included a 2-byte data header and a 1-byte training CRC. The frame structure of the example test messages included only: a. an unsigned 16-bit integer representing the frame prefix, b. an unsigned 8-bit integer representing the payload data; and c. an unsigned 8-bit integer representing the CRC data.

[0267] The frame prefix included the following fields: a. Flags (bits 14-15) with Bit 15: Outbound flag (Packet coming from a "master" device), and Bit 14: ACK requested flag (Outbound packet expects an ACK); b. Flood ID (bits 11-13) with a 3 bit counter (values 0 to 7) that differentiated different floods from each other because each flood sent through the network MUST use a packet ID different from the previous flood in order for devices to reset internal counters and flood knowledge — this value was incremented on each flood rather than just switching back and forth between two IDs in order to better handle devices with poor connections that may miss a flood entirely; c. Payload Length (bits 8-10) with a 3 bit value (0 to 7) that held the payload length minus one: this allowed the library to determine the location of the CRC byte and the end of the packet, and limited the maximum TX payload to 8 bytes; and d. Relay Counter (bits 0-7) with an 8 bit counter (0 to 255) that held the packet count of each individual transmission within a flood: this allowed each device in the flood to orient itself in time with respect to the start of the flood (assuming the packet transmit spacing is known).

[0268] The 2WM, upon receiving DATA from the WUC, processed the WUC received message, and proceeded to relay that message by activating the 2WM Tx circuitry, and started sending out the same message ID it received plus an updated hop count (and CRC). A typical experiment run was configured with a maximum hop count (defining how many times each message could be repeated / relayed within the network): after the hop count reached a maximum value, the node 1604 stopped further transmission.

[0269] As shown in Fig. 17, the measured time error (X axis in microseconds) from the repeated experiments (Y axis is number of runs) was generally less than + / - 100 microseconds. The histogram shows most of the nodes’ time signal is within + / -100 microseconds, suggesting good synchronisation.

[0270] As shown in Fig. 18, the measured message latency (Y axis in microseconds) from the repeated experiments (repeat number on the X axis) generally had a deviation from the mean of less than 60 microseconds.APPENDIX A - MESSAGES

[0271] Each data message may be referred to as a message or a "command" if a receiving node is configured to perform a function based on the message. Each message has a message type, e.g., one of the message / command types in the following (noting that one or more examples of these message / command types may be used with commercially available i-kon wired detonators and WEBGEN devices from ORICA):

Claims

CLAIMS1. A wireless device of a set of at least two wireless devices for forming respective nodes in a multihop through-the-earth (TTE) communication network, the wireless device including: a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one other wireless device in the set of wireless devices; a wireless transmitter (Tx) configured to transmit TTE signals representing an outgoing message to at least one other wireless device in the set of wireless devices; a stored selectable / predefmed data slot allocation, which defines one or more data slots and how the slots are divided; and a stored selectable / predefmed round timing, which defines one or more time windows for one or more rounds of communication, wherein the or each round uses the data slot allocation, wherein the wireless device is configured to: interpret the incoming message based on the incoming message or properties of the incoming message compared to the selectable / predefmed data slot allocation, and transmit the outgoing message according to the selectable / predefmed data slot allocation and the selectable / predefmed round timing, wherein the round timing controls the wireless device to concurrently transmit within at least one of the time windows with at least one other wireless device in the set of wireless devices, thus forming a concurrently communicating plurality of the nodes when the network is operating.I. The wireless device of claim 1, wherein the data slot allocation includes only 1 data slot in each round.

3. The wireless device of claim 1, wherein the data slot allocation includes 2 or more data slots in each round.

4. The wireless device of any one of claims 1 to 3, wherein the wireless device is configured to transmit the outgoing message in the same round as receiving the incoming message.

5. The wireless device of any one of claims 1 to 3, wherein the wireless device is configured to transmit the outgoing message in a different round from when the incoming message is received.

6. The wireless device of claim 4 or 5, wherein the wireless device is configured to transmit the outgoing message in a different slot from the one or more slots of the incoming message.

7. The wireless device of claim 4 or 5, wherein the wireless device is configured to transmit the outgoing message in at least one of same slots as the one or more slots of the incoming message, optionally in the same slot.

8. The wireless device of any one of the preceding claims, wherein the data slot allocation includes at least 2 bits in each data slot, or at least 3 bits in each data slot, or at least 4 bits in each data slot9. The wireless device of any one of claims 1 to 7, wherein the data slot allocation includes only 1 bit in each data slot.

10. The wireless device of any one of claims 1 to 8, wherein the data slots include a plurality of mutually different time slots.II. The wireless device of any one of claims 1 to 8, wherein the data slots include a plurality of mutually different frequency slots.

12. The wireless device of any one of claims 1 to 8, wherein the data slots include a plurality of mutually different code slots.

13. The wireless device of any one of the preceding claims, wherein properties of the incoming message include a type of the data slot, optionally a time slot, a frequency slot or a code slot.

14. The wireless device of any one of the preceding claims, wherein the TTE signals include magnetic induction (MI) signals, optionally including a carrier frequency of at least 1 kHz and no more than 200 kHz; and optionally of no more than 50 kHz, optionally of no more than 40 kHz, optionally of no more than 30 kHz, optionally of no more than 20 kHz, optionally of no more than 10 kHz, or optionally of no more than 5 kHz.

15. The wireless device of any one of the preceding claims, wherein the wireless device is configured to synchronise its clock using timing of the incoming message, optionally for a blasting delay.

16. The wireless device of any one of the preceding claims, wherein the wireless device is configured to generate the outgoing message by retransmitting the incoming message, thus enabling the data messages to flood across the network according to the stored selectable / predefmed round timing.

17. The wireless device of claim 16, including retransmitting the incoming message substantially immediately after a zero or negligible delay.

18. The wireless device of claim 16, including retransmitting the incoming message after a defined delay, optionally wherein the defined delay includes: (a) a fixed delay; (b) an adaptive delay; and / or (c) a delay count.

19. The wireless device of any one of claims 16 to 18, including retransmitting the incoming message when the incoming message is in a certain slot of the stored data slot allocation indicating that the incoming message is to be retransmitted as a flood message; and / or when a header of the incoming message indicates that the incoming message is to be retransmitted as a flood message.

20. The wireless device of any one of claims 16 to 19, wherein the wireless device is configured to generate outgoing messages in two or more of the data slots by retransmitting incoming messages received in two or more respective ones of the data slots, thus enabling two or more data messages to flood across the network simultaneously.

21. The wireless device of any one of the preceding claims, configured to recognise a node identifier (ID) in the incoming message in order to decide whether to generate the outgoing message.

22. The wireless device of any one of the preceding claims, wherein the wireless device is configured to generate the outgoing message based on any one or more of: a hop count determined from a hop court of the incoming message plus 1 ; the received TTE signals, optionally including a signal strength of the received TTE signals; stored data in the storage, optionally including a unique identifier (ID) of the wireless device in the set of wireless devices; and a timer of the wireless device, optionally a periodic timer.

23. The wireless device of any one of the preceding claims, wherein the wireless device is configured to generate the outgoing message based on at least one sensor measurement made by the wireless device, optionally including generating the outgoing message when the sensor measurement exceeds a predetermined threshold24. The wireless device of claim 23, wherein the at least one sensor measurement includes any one or more of a temperature measurement, a pressure measurement, a moisture measurement, a shock measurement, a pH measurement, a humidity measurement, an acceleration measurement, an orientation measurement, and a magnetic field measurement.

25. The wireless device of any one of the preceding claims, wherein the wireless device includes a housing configured and formed to seal and protect the wireless device from water and impact when deployed in a mining / blasting environment, wherein the housing is at least partially transparent to the TTE signals, thus allowing the TTE signals to travel at leastpartially through the protective housing from and / or to one or more antennas of the transmitter Tx and / or receiver Rx components.

26. The wireless device of any one of the preceding claims, wherein the wireless device includes at least one circuit-based processor, and machine-readable storage connected to the at least one circuit-based processor, wherein the machine-readable storage includes: the selectable / predefined data slot allocation and the selectable / predefmed round timing, and machine-readable instructions that control the at least one circuit-based processor to interpret the incoming message and transmit the outgoing message.

27. The wireless device of any one of the preceding claims, wherein the stored selectable / predefined data slot allocation and the stored selectable / predefined round timing are: hardcoded in the wireless device; encoded into the wireless device using an encoding machine; and / or received by the wireless device in a wireless message using a non-concurrent network protocol.

28. A multihop TTE communication system including: the wireless device of any one of claims 1 to 27; and at least one edge device that includes: at least one of: a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one other wireless device in the set of wireless devices, anda wireless transmitter (Tx) configured to transmit TTE signals representing an outgoing message to at least one other wireless device in the set of wireless devices; the selectable / predefined data slot allocation; and the selectable / predefined round timing, wherein the edge device includes at least one non-TTE communications device for non-TTE communication of the incoming message and / or the outgoing message to a control / monitoring system.

29. A multihop TTE communication system including: the wireless device of any one of claims 1 to 27; and at least one listen-only wireless device that includes: a wireless receiver (Rx) configured to receive TTE signals representing an incoming message from at least one other wireless device in the set of wireless devices; the selectable / predefined data slot allocation; and the selectable / predefined round timing, wherein the listen-only wireless device is configured to interpret the incoming message based on the incoming message or properties of the incoming message compared to the selectable / predefined data slot allocation.

30. A multihop TTE communication system including: the wireless device of any one of claims 1 to 27; and another of the wireless devices in the set arranged for TTE communication with the wireless device such that the wireless device is an intermediate node in the network.

31. A method of operating the through-the-earth (TTE) communication network formed of the set of wireless devices of any one of claims 1 to 27, the method including: a first one of the wireless devices generating TTE signals representing a first message; a second one of the wireless devices receiving the TTE signals representing the first message; the second one of the wireless devices transmitting TTE signals representing a second message based on the first message; and a third one of the wireless devices receiving the TTE signals representing the second message.

32. The method of claim 31, including one or more of: wireless blasting of the wireless device, signal surveying by the wireless device, sensing by the wireless device, and / or localization of the wireless device.

33. The method of claim 31 or 32, wherein the first one is: an edge node of the network; or a deep node of the network.

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