Wireless detonator initiation detection system and method based on magnetic induction through-the-earth bidirectional communication

Abstract

The present application relates to the field of civil blasting engineering, and discloses a wireless detonator initiation detection system and method based on magnetic induction through-the-earth bidirectional communication, wherein a ground station sends downlink instructions to a detonator in a blast hole with a buried depth of 1-10 m through a vertically placed low-frequency magnetic induction antenna, the detonator receives and demodulates through envelope detection in a parallel resonance state using the same coil, and the detonator transmits a hundred-milliwatt-level signal in a series resonance state using the same coil driven by a half-bridge push-pull, which is received by the ground station through a multi-coil array and detected through digital coherent accumulation and matched filtering, thereby realizing reliable bidirectional communication within a 500 m horizontal coverage range, implementing a double-confirmation safety initiation protocol, supporting networking registration, time-division multiplexing networking detection and abnormal detonator elimination. The present application solves the problems of serious signal attenuation in an underground environment, inability to communicate through the earth and poor group explosion synchronization accuracy of existing radio frequency wireless initiation.

Description

Technical Field

[0001] This invention relates to the field of civil blasting engineering technology, specifically to a wireless detonator initiation detection system and method based on magnetic induction through-ground two-way communication, which is particularly suitable for mining blasting scenarios with single-use, mission cycles not exceeding 24 hours, and burial depths of 1-10m. Background Technology

[0002] Among existing civilian blasting initiation technologies, wired initiation methods suffer from drawbacks such as cumbersome wiring and susceptibility to wire breakage and misfires; radio frequency wireless initiation (2.4GHz / 433MHz / LoRa) suffers severe attenuation at a burial depth of 1m and completely fails at a burial depth of 10m, making true through-ground communication impossible; existing magnetic induction through-ground communication is mostly used in mine rescue, but it has not solved the problems of bidirectional communication, network detection, and simultaneous initiation of multiple detonators under constraints such as detonator size (φ10cm×30cm), single use, 24-hour mission cycle, and burial depth of 1-10m.

[0003] Existing wireless detonator technologies typically aim for a standby lifespan of several years, employing complex low-power sleep-wake mechanisms, resulting in complex circuitry, high costs, and poor reliability.

[0004] However, in actual mining blasting operations, detonators are single-use items, and the time from loading to detonation is usually no more than 24 hours. Moreover, the burial depth is usually in the range of 1-10m, and there is no need for long standby. Therefore, the low-power design concept of existing technology does not match the real-world application scenario, resulting in unnecessary circuit complexity and cost waste.

[0005] Based on this, the present invention proposes a wireless detonator initiation detection system and method based on magnetic induction through-ground two-way communication. Summary of the Invention

[0006] The purpose of this invention is to provide a wireless detonator initiation detection system and method based on magnetic induction through-ground two-way communication.

[0007] The technical problem solved by this invention is: (1) Under the asymmetric link conditions of high-power transmission from the ground station and milliwatt-level uplink transmission from the detonator end, how to achieve reliable two-way through-ground communication with a horizontal coverage of 500m and a burial depth of 1-10m; (2) Under the conditions of only 100mAh disposable battery at the detonator end, 24-hour mission cycle, limited size, and burial depth of 1-10m, how to achieve multiplexing of the transmitting and receiving antennas and effective transmission of uplink signals; (3) How to perform status detection and anomaly removal of all detonators in the network before detonation to prevent duds and accidental detonations; (4) How to achieve microsecond-level synchronization accuracy during multi-detonator group detonation and eliminate the difference in magnetic induction propagation delay.

[0008] The objective of this invention can be achieved through the following technical solutions: First aspect: Wireless detonator detonation detection system based on magnetic induction and two-way communication through the ground: include: Ground station equipment is not limited by power consumption or size: A high-power magnetic induction transmitting module is configured to generate a low-frequency alternating magnetic field at a first frequency of 1kHz-10kHz and a transmitting power of 100W-500W. A high-sensitivity magnetic induction receiver array, consisting of multiple hollow induction coils, is configured to receive uplink signals from underground wireless detonators; The digital signal processing unit is configured to perform the following operations: The uplink receiving time slot window is determined based on the completion time of the downlink frame sent by the ground station to the underground wireless detonator. Within the uplink receive time slot window, a local orthogonal reference signal with the same frequency and phase synchronization as the uplink signal carrier is generated; The multi-channel induced voltage signals output by the high-sensitivity magnetic induction receiving array are respectively orthogonally down-converted with the local quadrature reference signal to obtain the in-phase component I-channel and the quadrature component Q-channel baseband signals. The I-channel baseband signal and the Q-channel baseband signal are low-pass filtered, and the filter cutoff frequency is 1 / 500 to 1 / 50 of the first frequency. Within a preset integration time window, coherent accumulation is performed on the filtered I-channel baseband signal and the Q-channel baseband signal respectively to obtain the accumulated in-phase value and the accumulated quadrature value; wherein, the processing gain of the coherent accumulation satisfies the relationship G=2·B·T int B is the equivalent noise bandwidth after low-pass filtering, and T int The duration of the preset integration time window; The complex signal formed by the accumulated in-phase value and the accumulated quadrature value is subjected to complex correlation operation with the locally pre-stored uplink frame preamble reference waveform to obtain the correlation peak value; When the correlation peak exceeds the adaptive noise threshold, the existence of the uplink signal is determined and demodulation is performed; the adaptive noise threshold is K times the noise standard deviation of the no-signal period within the uplink receiving time slot window, K≥5, and the preset noise floor is determined by system calibration; The network control terminal is configured to register, query, detect network connectivity, and control the detonation of multiple underground wireless detonators. The underground wireless detonator measures 30cm in length and 10cm in diameter, and has a built-in 100mAh battery configured for continuous power supply during a 24-hour mission. It includes: The same magnetic induction coil serves as both a receiving antenna and a transmitting antenna; The resonant switching module is configured to switch the coil between a parallel resonant receiving state and a series resonant transmitting state. The envelope detection and comparison module is configured to perform OOK demodulation on the downlink signal; The half-bridge push-pull drive module, composed of complementary MOSFET pairs, is configured to drive the coil to generate a low-frequency alternating magnetic field of the first frequency in the transmitting state. The mission-period power supply microcontroller is configured to operate continuously with power during the 24-hour mission cycle, and to execute the dual-confirmation safety detonation protocol, status feedback, and network detection. The ground station equipment and the underground wireless detonator achieve bidirectional communication through a magnetic induction ground-penetrating channel. Within a horizontal coverage range of 500m and a burial depth of 1-10m, the underground wireless detonator is continuously powered by the 100mAh battery during a 24-hour mission cycle, with an uplink transmission power of 50mW-200mW. The ground station equipment obtains a processing gain of 20dB-30dB through coherent accumulation, achieving reliable bidirectional communication.

[0009] Preferably, the operation of the digital signal processing unit in determining the uplink receive time slot window specifically includes: Record the reference time T0 when the high-power magnetic induction transmitting module completes the downlink frame transmission; T0+Δt is taken as the start time of the uplink receiving time slot window, where Δt is the fixed switching delay of the underground wireless detonator from downlink receiving state to uplink transmitting state, Δt=50ms-200ms; With T0+Δt+T frame As the end time of the uplink receive time slot window, where T frame The uplink frame transmission duration is specified; the phase of the local orthogonal reference signal remains continuous within the uplink receiving time slot window, or is compensated for phase at each sampling point according to the carrier frequency drift.

[0010] Preferred method: The coherent accumulation operation is specifically implemented through the following mathematical operations: The baseband signal sample value xI(n) of the I-path at the nth sampling time is accumulated: ; The Q-path baseband signal sample value xQ(n) at the nth sampling time is accumulated: Where N=f s ·T int f s T is the sampling rate of the digital signal processing unit. int The duration of the preset integration time window; The cumulative in-phase value is X I The cumulative orthogonal value is X Q ; The complex number related operations are: Where s(m) is the locally pre-stored uplink frame preamble reference waveform, M is the preamble length, and k is the sliding correlation offset.

[0011] Preferred: The adaptive noise threshold is determined as follows: At the start of the uplink receiving time slot window, the preset noise floor σ0 is directly used as the noise standard deviation. The preset noise floor σ0 is determined by the system factory calibration or by data collection during the no-signal period in the task initialization phase. Set the adaptive noise threshold V th =K·σ0, where K is the detection coefficient, and its value ranges from 5 to 10; When the relevant peak value Rmax > Vth, it is determined that the uplink signal exists; When the relevant peak value Rmax≤Vth, it is determined that there is no valid signal in the uplink receiving time slot window, and a no-acknowledgment flag is output to the network control terminal.

[0012] Preferably, the high-sensitivity magnetic induction receiving array includes 2×2 arranged 1m×1m square hollow coils with a center-to-center distance of 2m between each coil; before the digital signal processing unit performs coherent accumulation of the multiple induced voltage signals, it first performs phase alignment and amplitude weighting on the signals of each coil channel, so that the multiple signals are superimposed in phase to obtain array merging gain.

[0013] Preferably, the resonant switching module includes: The parallel resonant branch, controlled by a first analog switch, includes a resonant capacitor C connected in parallel with the coil. P , used for downlink reception status; The series resonant branch, controlled by a second analog switch, includes a resonant capacitor C connected in series with the coil. l , used for uplink transmission state; The quality factor of the parallel resonant branch is 30-80, and the quality factor of the series resonant branch is 5-15; the microcontroller controls the mutual exclusion of the first analog switch and the second analog switch through GPIO signals.

[0014] Preferably, the half-bridge push-pull drive module includes a complementary pair of P-channel MOSFETs and N-channel MOSFETs, the gates of which are directly driven in an inverting manner by two GPIO ports of the ultra-low power microcontroller; the supply voltage of the complementary pair is the rated voltage of the 100mAh battery, 3.0V-3.7V; the half-bridge push-pull drive module and the series resonant branch form a series resonant circuit, and the resonant frequency of the series resonant circuit is equal to the first frequency.

[0015] Preferably, the digital signal processing unit performs multi-frame incoherent combining within the uplink receive time slot window. When the underground wireless detonator continuously transmits L frames of uplink data within a single uplink receiving time slot window, where L≥2, the digital signal processing unit performs coherent accumulation on each frame to obtain L complex correlation peaks. The incoherent merged peak is obtained by taking the modulus of the L complex correlation peaks and then calculating their arithmetic mean.

[0016] Where R l The complex correlation peak value of the l-th frame; The incoherently merged peak R noncoh The signal is compared with the adaptive noise threshold to determine whether the uplink signal exists; the multi-frame incoherent combining obtains approximately 10 log [value missing] additionally compared to single-frame detection. 10 (L)dB of combined gain.

[0017] The second aspect: A wireless detonator initiation detection method based on magnetic induction through-ground two-way communication, including the following steps: S1 Network Registration: The ground station sends a registration frame to each detonator through the downlink magnetic induction channel. After the detonator is coded, it enters the network to be detonated and sends back a registration confirmation frame in the allocated time slot. S2 Network Detection: The ground station polls each detonator through time-division multiplexing. Each detonator sends back a status frame in the corresponding time slot. The status frame includes information such as delay time, charging status, and battery level. The ground station determines whether the detonator network meets the detonation conditions based on the sent-back status and marks and removes abnormal detonators. S3 Pre-detonation: The ground station sends a pre-detonation frame containing a countdown time window and a first verification code. The countdown time window is 3 seconds to 10 seconds. After the detonator continuously receives and verifies the data, it enters the pre-detonation state, starts a local countdown, and sends back a pre-detonation confirmation frame in a fixed time slot. The start time of the fixed time slot is determined by a preset delay after the detonator completes the downlink frame reception. The preset delay is 50ms to 200ms. S4 uplink signal coherent accumulation detection: The ground station performs the following operations within the fixed time slot: A local quadrature carrier signal is generated, wherein the frequency of the local quadrature carrier signal is equal to the uplink signal carrier frequency, and the phase is locked based on the downlink frame synchronization reference; The multiple induced voltage signals output by the receiving array are multiplied by the local quadrature carrier signal, and then low-pass filtered to obtain the baseband complex signal. Within a preset integration time window Tint, the real and imaginary parts of the baseband complex signal are sampled and accumulated respectively to obtain a coherent cumulative value; the preset integration time window Tint int The value ranges from 3 seconds to 10 seconds, making the processing gain G = 2·B·T int Satisfying 20dB≤10·log 10 (G)≤30dB, where B is the equivalent noise bandwidth after low-pass filtering; The coherent cumulative value is subjected to sliding correlation operation with the locally pre-stored uplink frame preamble reference waveform. When the correlation peak value exceeds the noise threshold, it is determined that the pre-detonation confirmation frame has arrived. S5 Confirm Detonation: The ground station sends a confirmation detonation frame containing the same first verification code within the countdown time window. After the detonator verification is passed, the MOS tube is triggered to perform detonation. S6 Abnormal Cancellation: If a cancellation frame is received within the countdown time window, or if the confirmation detonation frame is not received within the timeout period, the detonator will automatically detonate.

[0018] Preferably, the equivalent noise bandwidth B of the low-pass filter is 2Hz-20Hz; the preset integration time window T int The processing time is 3 to 30 seconds; the processing gain G = 2·B·T int The value range is 100-1200, corresponding to a sensitivity improvement of 20dB-31dB.

[0019] Preferably, the first verification code is an 8-bit random number randomly generated by the ground station at the start of each detonation mission; after entering the verification detonation state, the detonator stores the first verification code in a non-volatile memory and performs detonation only when it receives the confirmation detonation frame containing the same first verification code; if the verification code in the received confirmation detonation frame is inconsistent with the stored first verification code, or the countdown time window has expired, the detonator refuses to detonate and releases the preparation detonation state.

[0020] Preferably, when the network control terminal performs time-division multiplexing polling, it allocates time slots according to the following algorithm: Establish polling cycle T cycle The polling period T cycle Broadcast registration time slot T bSingle detonator uplink time slot T s Protection interval T g and the number of online detonators N online Together, they satisfy the following relation: T cycle =T b +N online ·T s +T g ; Among them, T b =0.5s-1.0s, T s =0.3s-0.6s, T g = 0.3s-0.5s, T s The value is determined by the sum of the uplink frame transmission duration and the transmit / receive switching protection time; At the beginning of each polling cycle, the ground station sends a broadcast registration frame, and the address code of the broadcast registration frame is an all-1 broadcast address; After receiving the broadcast registration frame, each of the underground wireless detonators counts the number N of online detonators according to its own pre-stored detonator ID. online Modulus calculation to determine local time slot offset:

[0021] ID i This is a unique identifier for the i-th detonator; The time slot offset Δt of each of the underground wireless detonators in the local machine slot (i) Upon arrival, the status frame is transmitted within a dedicated uplink time slot with a duration of Ts; The digital signal processing unit of the ground station opens the uplink receiving time slot window within each dedicated uplink time slot, and closes the coherent accumulation operation after the uplink receiving time slot window ends, and enters the listening preparation for the next time slot.

[0022] Preferably, the ground station performs anomaly detection and time slot reallocation after each polling cycle. If a detonator does not generate a correlation peak exceeding the adaptive noise threshold within its dedicated uplink time slot, or if the status code in the status frame indicates an anomaly, the network control terminal marks the detonator as INVALID and removes it from the number of online detonators N. online Remove from the middle; The network control terminal updates the number of online detonators N_o in the next polling cycle. nline' =N_ online -N_ invalid And recalculate the time slot offset of the remaining valid detonators, so that the dedicated uplink time slots of the valid detonators are arranged compactly within the polling period, thus shortening the polling period; Detonators marked as INVALID will no longer receive pre-detonation frames in subsequent detonation missions until they are manually checked on-site and re-registered.

[0023] Preferably, during the S2 network detection phase, the ground station synchronously performs equivalent communication delay calibration for each detonator, the equivalent communication delay calibration including: The digital signal processing unit of the ground station records the coherent cumulative peak amplitude A of the status frames transmitted back by each of the underground wireless detonators in its dedicated uplink time slot. i ; Based on the known correlation model between magnetic induction coupling strength and equivalent propagation distance, according to the coherent cumulative peak amplitude A i The equivalent propagation distance r of the i-th detonator is calculated by reverse calculation. i The association model is as follows:

[0024] Where K sys f is the system gain constant, determined by the equivalent magnetic moment of the ground transmitter, the equivalent magnetic moment of the detonator receiving coil, and the front-end amplification gain. opt The optimal operating frequency is σ; σ is the formation equivalent conductivity. The equivalent propagation distance r i Calculate the horizontal distance based on the known burial depth d.

[0025] Based on the time delay-distance mapping table calibrated in the experiment, the equivalent communication delay τ of the i-th detonator is obtained. i The time-delay-distance mapping table is established through field calibration, characterizing the combined time delay required for the magnetic induction signal to propagate through the ground and for the receiving link response to be established, and the equivalent propagation distance r. i The correspondence; The minimum equivalent communication delay τ among all online detonators min Based on this, calculate the time delay compensation value for each detonator: Δt comp_i =τ i −τ min ; During the S3 pre-detonation phase, the ground station embeds the delay compensation value Δtcomp_i of each detonator into the delay compensation field of the corresponding detonator's pre-detonation frame and sends it out; when each detonator enters the pre-detonation state, it sets the local countdown timer T. countdown The initial value is set as follows: T countdown_i =T base −Δt comp_i ; Where T base To standardize the baseline countdown value, it is determined by the time window field in the pre-detonation frame, T. base=3s-10s; During the S5 confirmation detonation phase, the ground station broadcasts a confirmation detonation frame; upon receiving the confirmation detonation frame, each detonator synchronously starts its respective local countdown timer T. countdown_i When the T countdown_i When the value decreases to zero, the MOS transistor is triggered to initiate the explosion; or, when the T value decreases to zero... countdown_i If the timeout occurs and no valid confirmation detonation frame is received, the detonation preparation state will be automatically cancelled. Through the aforementioned time delay compensation, detonators with a greater horizontal distance are affected by Δ tcomp_i Larger T countdown_i The detonator that is closer in horizontal distance will detonate first due to Δt. comp_i Smaller but larger T countdown_i The detonation occurs after the detonation; the time difference between the initial and subsequent detonations cancels out the equivalent communication delay difference caused by the difference in horizontal distance between each detonator, so that all detonators detonate at the same absolute moment after the arrival of the confirmed detonation frame, and the synchronization error is controlled within ±1ms.

[0026] As a further explanation of the present invention: the ground station equipment is deployed on the surface of the blasting area, powered by a vehicle-mounted battery (12V / 30Ah), with a total weight of about 35kg, and can be set up by two operators; The function is to generate a low-frequency alternating magnetic field of 1kHz-10kHz through a high-power magnetic induction transmitting module and send downlink commands to the detonator in the burial depth of 1-10m. Uplink status frames from detonators are received via a high-sensitivity receiver array. Coherent accumulation and matched filtering detection are performed by a digital signal processing unit; The registration, polling, and swarm control of up to 100 detonators can be completed through a networked control terminal.

[0027] The underground wireless detonator has a cylindrical metal shell, 30cm long and 10cm in diameter. It has a built-in 100mAh disposable lithium thionyl chloride battery (ER14505, 3.6V), designed to provide continuous power during the 24-hour mission cycle. After the mission is over, it will be destroyed along with the detonator and will not need to be replaced or recharged. The internal components include a mission-powered microcontroller (STM32G030F6P6 or MSP430FR2000), a transceiver multiplexing coil (wound in a groove on the outer wall of the housing), a half-bridge driver board (SI2301 / 2302), an envelope detector and comparator circuit (BF862+TLV2401+LMV7219), a thyristor trigger circuit (2N6565), and an electric detonator interface.

[0028] The magnetic induction ground-penetrating channel uses soil and rock layers as the propagation medium. Under the conditions of 5kHz frequency and ground conductivity σ=0.01S / m, the skin depth δ≈71m. At 2 kHz, δ≈113 m; at 1 kHz, δ≈160 m; Since the actual burial depth is 1-10m, when the burial depth << δ (e.g., 1m / 5kHz), the formation absorption loss is relatively small. When the burial depth approaches δ (e.g., 10m / 5kHz), the eddy current loss increases significantly. Therefore, a strategy of selecting the frequency based on formation conductivity and burial depth is adopted: higher frequencies (5kHz-10kHz) can be used in shallow layers (1-3m) to obtain higher rates; medium frequencies (3kHz-5kHz) are used in middle layers (3-6m); and low frequencies (1kHz-2kHz) must be used in deep layers (6-10m) to maintain sufficient skin depth and reduce formation absorption loss.

[0029] As a further explanation of the present invention: 24-hour mission power supply strategy Since the mission cycle is only 24 hours, the system power consumption budget has been relaxed from microamp-level standby to milliamp-level continuous operation: Microcontroller: operates continuously at 1MHz, with a current of approximately 150μA to -500μA, and consumes approximately 3.6mAh to 12mAh of power in 24 hours; Receiver link (BF862+TLV2401+LMV7219): Continuously on, current draw is approximately 120μA, power consumption is approximately 2.9mAh in 24 hours; Uplink transmission (half-bridge drive): with a power of 100mW-200mW, a duty cycle of 1%-10%, an average current of about 2mA-5mA, and a power consumption of about 48mAh-120mAh in 24 hours; in practice, by controlling the duty cycle (such as 1%-2%), the total power consumption of transmission in 24 hours is limited to within 50mAh. Resonant switching and drive loss: average 0.5mA, power consumption of approximately 12mAh in 24 hours; Total power consumption budget: 12mAh for microcontroller + 3mAh for receiver link + 50mAh for uplink transmitter + 35mAh reserved = 100mAh, which meets the needs of 24-hour mission.

[0030] Since there is no need for long standby times, all modules are continuously powered throughout the task cycle, eliminating the need for deep sleep, inductive power supply, or complex power management timing control, which greatly simplifies the circuit and improves reliability.

[0031] As a further explanation of the present invention: bidirectional communication method and link budget Downlink communication (ground to detonator): The ground station transmits downlink frames using optimal OOK modulation. The frame structure is: 16-bit preamble (10101010...) + 16-bit address code + 8-bit group number + 8-bit instruction code + 8-bit time window + 8-bit verification code + 8-bit CRC-8, with a rate of 50-200bps. A 2-second continuous carrier wave is transmitted before transmission. Uplink communication (detonator to ground): The detonator reuses the same coil and switches to the series resonance state after a delay of Δt=50-200ms after the downlink frame ends, and is driven by the half-bridge to send the uplink frame; The uplink frame structure is: 8-bit preamble + 16-bit address code + 8-bit status code + 8-bit voltage value + 8-bit CRC-8, with a data rate of 100bps and a single frame duration of 480ms. The ground station operates within a fixed uplink receiving time slot window (T0+Δt to T0+Δt+T_). frame Enable coherent cumulative reception within )

[0032] Link budget verification (worst-case conditions: burial depth 10m, horizontal distance 500m, σ=0.01S / m, f=2kHz): Downlink budget Ground launch: 300W, vertical ring 0.6m, 300 turns, equivalent magnetic moment m≈678A·m²; Equivalent propagation distance ; Skin depth δ = 113 m (2 kHz), eddy current attenuation G = e^(-r / δ) = e^(-4.42) ≈ 0.012; The magnetic field generated on the ground at the detonator: B = (μ0·m) / (4π·r³)·G ≈ 2.6 × 10⁻⁶ -12 T; The induced voltage at the detonator end with a 300-turn coil (A=π×0.05²) is: V_rx=2πf·N·A·B≈2π×2000×300×7.85×10 -3 ×2.6×10 -12 ≈77nV; After amplification via parallel resonance (Q=50): V_coil≈3.9μV; After being amplified 20 times by JFET: V_amp≈78μV, which is much higher than the comparator threshold and has sufficient margin.

[0033] Uplink budget (under the same conditions): Detonator emission: 150mW, equivalent magnetic moment m≈0.14 A·m²; Induced voltage of a single ground coil (1m×1m, 100 turns): V_ind=2πf·N·A·B≈2π×2000×100×1×(μ0·m·G) / (4π·r³)≈0.8μV; Combined via a 4-coil array (+6dB): V_array≈1.6μV; After being amplified by 92dB (+39800 times) at the front end: V_adc≈64mV; Noise floor: Front-end noise approximately The equivalent bandwidth is 10Hz, and the total noise is approximately 63nV. The original SNR was approximately 25 (28 dB). After coherent accumulation for 5 seconds (+20 dB), the SNR_out was approximately 48 dB, and the bit error rate was << 10. -6 .

[0034] If the burial depth is 10m and σ=0.05S / m (aquifer), the skin depth drops to 50m, and the attenuation intensifies. At this point, the system can be switched to 1kHz (δ=113m→160m), and the coherence accumulation time can be extended to 10-30 seconds (processing gain +23dB-+28dB) to maintain reliable communication.

[0035] As a further explanation of the present invention: Dual-Confirmation Safe Detonation Protocol Implemented using a finite state machine, the transition rules are as follows: STANDBY→REGISTERED: Broadcast registration frame received, CRC passed, slot ID extracted; REGISTERED→ACTIVE: If ≥2 identical pre-detonation frames are received consecutively, with address matching, CRC passing, and verification code consistent, start a countdown (3-10 seconds) and send back confirmation; ACTIVE→DETONATED: Upon receiving a confirmation detonation frame, the address and verification code match and the timeout has not occurred, the MOS transistor is turned on, and detonation is executed. ACTIVE→ABORTED: Automatically deactivated upon receiving a cancellation frame or without receiving an acknowledgment detonation frame within a timeout period; The first verification code is generated by the ground station random number generator (seed is the XOR of the timestamp and the mission number), 8 bits, and is embedded in the pre-detonation frame at the start of the detonation mission. It is written to the memory and comparison register when the detonator enters the active state; it is cleared immediately after detonation or cancellation to prevent replay attacks.

[0036] The beneficial effects of this invention are: This invention provides reliable bidirectional through-ground communication covering depths of 1-10m: through frequency adaptation (1kHz-10kHz) and coherence accumulation time adaptation (3s-30s), it satisfies the link budget under conditions of 500m horizontal coverage, 1-10m burial depth, and different geological conductivity, with a bit error rate << 10. -6 .

[0037] This invention provides continuous power supply during 24-hour operation without the need for complex power management: all modules operate continuously with a total power consumption of << 80mAh, with a 20mAh margin reserved. It eliminates complex circuits such as deep sleep mode, inductive power supply, and adaptive frequency reduction, improving reliability and reducing costs by approximately 30%. This invention's dual-confirmation mechanism completely eliminates accidental detonation: it employs a pre-detonation-status feedback-confirmed detonation dual-confirmation closed loop, combined with an 8-bit random verification code and a 3-10 second countdown time window, resulting in an accidental detonation probability of less than 10%. -10 .

[0038] Rapid network detection: Time-division multiplexing polling can complete the network status detection of 100 detonators within 10 seconds and remove abnormal detonators in real time; Formation adaptation and group explosion synchronization: The optimal frequency is selected based on the formation conductivity, and a synchronization accuracy of ±1ms is achieved through time difference compensation; The project is highly feasible: the ground station's transmitting ring uses PVC pipe and copper wire, which can be set up by two people in 10 minutes; the detonator terminal circuit is a standard industrial component, which does not require customized ASIC, and the one-time use cost is controllable. Attached Figure Description

[0039] The invention will now be further described with reference to the accompanying drawings.

[0040] Figure 1 This is a diagram of the overall system architecture of the present invention.

[0041] Figure 2 This is a circuit diagram of the high-power magnetic induction transmitting module for the ground station of the present invention.

[0042] Figure 3 This is a circuit diagram of the transceiver multiplexing antenna switching circuit at the detonator end of the present invention.

[0043] Figure 4 This is a diagram of the push-pull drive circuit for the detonator end of the present invention.

[0044] Figure 5 This is a diagram of the receiving link at the detonator end of the present invention.

[0045] Figure 6 This is a diagram showing the layout of the high-sensitivity receiver array for the ground station of this invention.

[0046] Figure 7 This is a flowchart of the digital coherent accumulation and matched filtering process of the present invention. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0048] System Overall Architecture like Figure 1 As shown, the wireless detonator detonation network detection system based on magnetic induction and two-way communication in this embodiment includes two main parts: ground station equipment and underground wireless detonators. The ground station equipment is deployed on the surface of the blasting area, powered by a vehicle-mounted battery (12V / 30Ah), and weighs approximately 35kg. It can be set up by two workers within 10 minutes.

[0049] The underground wireless detonator has a cylindrical metal casing, 30cm long and 10cm in diameter, and contains a 100mAh disposable lithium thionyl chloride battery (ER14505, 3.6V). It is designed to provide continuous power during the 24-hour mission cycle and will be destroyed along with the detonator after the mission is completed. The internal components include a mission-powered microcontroller (STM32G030F6P6, 16MHz main frequency, approximately 500μA operating current), a transmit / receive multiplexer coil, a half-bridge driver board, an envelope detector and comparator circuit, a MOSFET trigger circuit, and a detonator interface. Example 2

[0050] Ground station high-power magnetic induction transmitting module like Figure 2 As shown, the ground station transmission module consists of four stages: signal generation, power amplification, filtering and matching, and transmission antenna. Level 1: The TIM2 timer of the STM32F103C8T6 microcontroller generates a 1kHz-10kHz square wave. OOK modulation is achieved by controlling the on / off state of the square wave through GPIO. The frame rate is adjusted according to the frequency: 200bps at 10kHz, 100bps at 5kHz, 50bps at 2kHz, and 25bps at 1kHz. The second stage: The IRS2092 driver chip, together with the IRF7484 MOSFET, forms a full-bridge Class-D power amplifier with a switching frequency of 200kHz, a supply voltage of ±55V, a rated output power of 300W / 4Ω, and an efficiency of >90%. The third stage: The transmitting antenna is a vertical circular ring, made by bending a 4-point PVC water pipe into a 0.6m diameter ring, supported by a tripod. The coil plane is calibrated to be perpendicular to the ground using a bubble level (error << 3°). The coil is tightly wound with 300 turns of 1.5mm² multi-strand copper wire. The measured inductance L1 = 8.2mH, DC resistance R_dc = 3.5Ω, and the series resonant capacitor switches according to the frequency. Example 3

[0051] Detonator-end transmit / receive multiplexing antenna switching circuit like Figure 3 As shown, the detonator terminal uses only one coil L_coil to achieve transmit and receive multiplexing, and switches between the receive and transmit states through a resonant switching module; The coil is wound in the annular groove on the outer wall of the detonator shell, using 300 turns of 0.15mm enameled wire. The measured inductance L_coil=3.1mH and DC resistance R_coil=32Ω. Parallel resonant receiver branch: SW1 (TS5A3160) controls Cp / / connected in parallel to the two ends of the coil. Different capacitor values ​​are used according to the on-site operating frequency. Q≈50, high impedance amplification is beneficial for reception. Series resonant transmission branch: SW2 controls Cs to be connected in series between the coil and the half-bridge. Different capacitor values ​​are used according to the operating frequency on site. Q≈5~15. Low impedance and large current are beneficial for transmission. Switching timing: During the mission, the power supply microcontroller is controlled by GPIO. In the receive state, SW1 is closed and SW2 is open. After the downlink frame ends, there is a 100ms delay before SW1 is opened and SW2 is closed to enter the transmit state. After the uplink frame is sent, it switches back to the receive state. Example 4

[0052] Detonator end half-bridge push-pull drive circuit like Figure 4 As shown, the half-bridge push-pull drive module consists of complementary MOSFET pairs, freewheeling diodes, series resonant capacitors, and a microcontroller control interface. Q1 uses SI2301CDS (P-channel), Q2 uses SI2302CDS (N-channel), the gate is connected to GPIO_P2.0 / P2.1 of STM32G030 through a 100Ω resistor, driven in an inverting mode, and the freewheeling diodes D1 / D2 use 1N4148 to protect the MOSFET body diode; Since the mission lasts only 24 hours, the battery directly powers the half-bridge without the need for complex energy storage capacitors. The ER14505 battery has an internal resistance of about 5Ω and can directly provide a peak current of 60mA. Transmit power verification: The half-bridge output ±1.8V square wave (3.6Vpp), after being filtered by the series resonant circuit, has a peak coil current of about 60mA and a transmit power of about 100mW-150mW. Under the conditions of 10m burial depth, 500m horizontal distance, 2kHz frequency, and σ=0.01S / m, this power can generate a signal-to-noise ratio of >25dB after being coherently accumulated by the ground receiving array. Example 5

[0053] Detonator receiver link and 24-hour power consumption budget like Figure 5 As shown, the receiving link starts from the parallel resonance of the coils, and then passes through the JFET preamplifier, bandpass filter, envelope detector, comparator, and finally outputs digital baseband to the microcontroller. First stage: After parallel resonance, the impedance Z_p≈4.8kΩ, directly coupled to the BF862JFET preamplifier. The BF862 adopts self-biased common-source amplification, with an operating point Id≈0.5mA and a gain of about 20 times (26dB). Second stage: TLV2401 single op-amp forms an MFB bandpass filter with a center frequency of 1kHz-10kHz, Q≈5, gain of 10 times (20dB), and the power supply is regulated from 3.6V to 1.8V by LDO; Third stage: 1N4148 diode + RC envelope detector, τ=1ms, output baseband pulse; The fourth stage: LMV7219 comparator, which uses an adaptive threshold circuit, tracks 50% of the signal amplitude during the preamble as a dynamic threshold; 24-hour power consumption budget is attached. Figure 5 As shown in the table: the microcontroller continuously operates at 12mAh + the receiver link is continuously on at 3mAh + the uplink transmit at 50mAh + the reserved 35mAh = 100mAh, which meets the requirements of a 24-hour mission. Example 6

[0054] Ground station high-sensitivity receiver array deployment like Figure 6 As shown, the receiving array adopts a 2×2 topology, with a total footprint of 4m×4m; A single coil is made of 1m×1m square frame bent from 4-point PVC water pipe, with 100 turns and an inductance of about 2.5H; a 410pF mica capacitor and a 100kΩ damping resistor are connected in parallel, Q≈20, and the bandwidth is 250Hz. The four coils are spaced 2m apart, and each coil is placed in a waterproof aluminum box. Inside the box are a BF862 preamplifier board and an AD620 instrumentation amplifier board (66dB gain). The four outputs are converged to the central FPGA / DSP processing unit via twisted shielded cables. Array combining: The four signals are coherently added after phase alignment, and the measured combining gain is about +6dB; the total front-end gain is 92dB, and the uplink signal reaches tens of mV after amplification, which can be comfortably processed by the subsequent ADC. Example 7

[0055] Digital coherent accumulation and matched filtering processing like Figure 7 As shown, the FPGA within the central processing unit performs the following digital signal processing: Sampling and Quadrature Down-Conversion: The ADS1256 samples at 50kSPS, and generates local quadrature carriers I_ref / Q_ref in the FPGA, which are multiplied with the sampled signal to obtain x_I(n) / x_Q(n); Low-pass filter: 128th order FIR low-pass filter, with an equivalent noise bandwidth B=20Hz at a cutoff frequency of 10kHz; Coherent accumulation: in T int Internal accumulation For each sample point, the processing gain is G = 2·B·T. int ; Matched filtering: It is correlated with the local preamble reference waveform. The preamble length becomes grayed out with the rate. When the current preamble is aligned, a correlation peak R_max is generated.

[0056] Threshold detection: Based on the preset noise floor σ0, set the threshold V. th =5·σ0, K=5-10, if Rmax>Vth, the signal is determined to exist. Example 8

[0057] Double confirmation safe detonation sequence The complete process for a single detonation is as follows: T=0-2s: continuous carrier wave, power 100W-500W, detonator coil receives energy, battery directly powered; T=2.0s, 2.7s, 3.4s: The ground station continuously sends 3 identical pre-detonation frames, with a countdown time window of 3-10 seconds.

[0058] Detonator end processing: During the mission, the power supply microcontroller continuously listens in STANDBY / REGISTERED state. After receiving two identical pre-detonation frames, it verifies the address, CRC, and verification code. After successful verification, it writes the information to the memory, starts the TIMER_B countdown (e.g., 3 seconds), switches the state to the ready-to-detonate state, and sends an uplink confirmation frame after a 100ms delay. T=3.7s: Uplink receiving window, the ground station performs 5 seconds of coherent accumulation, and displays "Detonator #1 is ready" after detecting uplink confirmation; T = 4.0s - 7.0s: Manual confirmation window (3 seconds), detonation after operator confirmation; T=7.0s, 7.7s, 8.4s: Confirm detonation frame; the verification code must be consistent with the pre-detonation frame. Final decision at the detonator end: If the verification code matches and TIMER_B has not timed out, the MOSFET is triggered, the detonation occurs, and the state is locked (DETONATED). If the code does not match or times out, the detonator is ABORTED. Example 9

[0059] Network detection time division multiplexing The network testing process for 100 detonators is as follows: Step 1: Broadcast registration frame (address 0xFFFF, duration 0.5s); Step 2: Allocate time slot offsets for each detonator according to ID_i mod 100. For example, for the detonator with ID=0x0001, Δt_slot=0.5s+(1mod100)×0.5s=1.0s; Step 3: Polling and status feedback, T_s=0.5s, polling cycle for 100 detonators T_cycle=0.5s+100×0.5s+0.5s=51s; Step 4: Anomaly detection. Detonators that do not respond or have an abnormal status are marked as INVALID and removed. They are then compactly rearranged in the next polling cycle. Step 5: Only normal detonators are introduced into the detonation network. Example 10

[0060] Multi-detonator synchronous detonation time difference compensation During the network detection phase, the ground station calculates the coherent cumulative peak amplitude A of each detonator status frame. i Back-calculation of equivalent propagation distance r i τ is obtained by looking up the delay-distance mapping table. i , with τ min Calculate Δt based on the baseline comp_i =τ i -τ min Embedded pre-detonation frame delivery, countdown initial value T _countdown_i =T _base-Δt_comp_i T _base =3-10s, after confirming the broadcast of the detonation frame, each detonator starts the countdown synchronously, with the distant detonator detonating first and the close-range detonator detonating later to offset the difference in propagation time delay, and the synchronization error is <<±1ms.

[0061] Time delay calibration was performed based on the time delay-distance mapping table calibrated through field testing (obtained in advance by oscilloscope measurement in a standard formation), as shown in Table 1: Table 1

[0062] As shown in Table 1: (Referring to the table...) =1.2ms, similarly, detonator #100 (farthest, =500m) reverse push ≈501m, =5.5ms.

[0063] Delay compensation calculation. Using the minimum... =1.2ms as the baseline: Detonator #1: =1.2-1.2=0ms Detonator #100: =5.5-1.2=4.3ms Countdown pre-compensation. Unified benchmark countdown. =3000ms (30 seconds). When the pre-detonation frame is sent: Initial countdown value for detonator #1: =3000-0=3000ms Initial countdown value for detonator #100: =10000-4.3=9995.7ms.

[0064] Synchronous detonation is executed, with the ground station broadcasting a confirmation detonation frame at T=0. Upon receiving this confirmation, all detonators synchronously activate their respective TIMER_B. Detonator #100 detonated after 9995.7ms (absolute time T=9995.7ms). Detonator #1 detonates after 10,000 ms (absolute time T = 10,000 ms). Since the magnetic induction propagation delay of detonator #100 is 4.3ms longer than that of detonator #1, and its countdown ends 4.3ms earlier, the absolute detonation time difference between the two is <1ms. The actual measured synchronization error of 100 detonators in a group explosion is <±0.8ms, which meets the requirements of high-precision blasting. Error sources analysis mainly includes: propagation speed variation caused by uneven formation conductivity (<0.3ms), MCU timer crystal oscillator deviation (±50ppm, cumulative <0.5ms within 10 seconds), and differences in the air transmission time of the confirmed detonation frame (only 1.7μs at the speed of light for a distance of 500m, which can be ignored). Through crystal oscillator temperature compensation and formation zoning calibration, the synchronization error can be further compressed to within ±0.5ms.

[0065] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A wireless detonator detonation detection system based on magnetic induction through-ground two-way communication, characterized in that, Including ground station equipment and underground wireless detonators: The ground station equipment includes a high-power magnetic induction transmitting module, a high-sensitivity magnetic induction receiving array, and a digital signal processing unit. The underground wireless detonator includes a single magnetic induction coil that serves as both a receiving and transmitting antenna, a resonant switching module, an envelope detection and comparison module, a half-bridge push-pull drive module, and a mission-side power supply microcontroller. The ground station equipment and the underground wireless detonator achieve bidirectional communication through a magnetic induction ground-penetrating channel; The ground station equipment obtains processing gain through coherent accumulation, enabling reliable two-way communication.

2. The wireless detonator initiation detection system based on magnetic induction through-ground bidirectional communication according to claim 1, characterized in that, The high-power magnetic induction emission module is configured to generate a low-frequency alternating magnetic field of a first frequency; The first frequency is 1kHz-10kHz, and the transmission power is 100W-500W; The uplink transmission power of the underground wireless detonator is 50mW-200mW; The underground wireless detonator has a length of 30cm and a diameter of 10cm, and has a built-in 100mAh battery.

3. The wireless detonator initiation detection system based on magnetic induction through-ground bidirectional communication according to claim 1, characterized in that, The digital signal processing unit is configured to perform the following operations: determine the uplink reception time slot window based on the completion time of the downlink frame sent by the ground station to the underground wireless detonator; Within the uplink receive time slot window, a local orthogonal reference signal with the same frequency and phase synchronization as the uplink signal carrier is generated; The multi-channel induced voltage signals output by the high-sensitivity magnetic induction receiving array are respectively orthogonally down-converted with the local quadrature reference signal to obtain the in-phase component I-channel and the quadrature component Q-channel baseband signals. Low-pass filtering is performed on the I-channel baseband signal and the Q-channel baseband signal; Within a preset integration time window, the filtered I-path baseband signal and the Q-path baseband signal are coherently accumulated to obtain the accumulated in-phase value and the accumulated quadrature value. The complex signal formed by the accumulated in-phase value and the accumulated quadrature value is subjected to complex correlation operation with the locally pre-stored uplink frame preamble reference waveform to obtain the correlation peak value; When the correlation peak exceeds the adaptive noise threshold, the existence of the uplink signal is determined and demodulation is performed.

4. The wireless detonator initiation detection system based on magnetic induction through-ground bidirectional communication according to claim 3, characterized in that, The processing gain of the coherent accumulation is G = 2·B·T int ; Where B is the equivalent noise bandwidth after low-pass filtering, and T int The duration of the preset integration time window; The adaptive noise threshold is K times the noise standard deviation during the no-signal period within the uplink receiving time slot window, where K ≥ 5, and the preset noise floor is determined by system calibration.

5. The wireless detonator initiation detection system based on magnetic induction through-ground bidirectional communication according to claim 3, characterized in that, The operation of the digital signal processing unit to determine the uplink receiving time slot window specifically includes: recording the reference time T0 when the high-power magnetic induction transmitting module completes the downlink frame transmission; T0+Δt is taken as the start time of the uplink receiving time slot window, where Δt is the fixed switching delay of the underground wireless detonator from downlink receiving state to uplink transmitting state, Δt=50ms-200ms; With T0+Δt+T frame As the end time of the uplink receive time slot window, where T frame This is the uplink frame transmission duration.

6. The wireless detonator initiation detection system based on magnetic induction through-ground bidirectional communication according to claim 1, characterized in that, The resonant switching module is configured to switch the coil between a parallel resonant receiving state and a series resonant transmitting state. The parallel resonant branch includes a resonant capacitor C connected in parallel with the coil. P , used for downlink reception status; The series resonant branch includes a resonant capacitor C connected in series with the coil. I , used for uplink transmission state; The microcontroller controls the mutual exclusion of the parallel resonant branch and the series resonant branch through GPIO signals.

7. The wireless detonator initiation detection system based on magnetic induction through-ground bidirectional communication according to claim 1, characterized in that, The half-bridge push-pull drive module is composed of complementary MOSFET pairs and is configured to drive the coil to generate a low-frequency alternating magnetic field of the first frequency in the transmitting state. The gates of the complementary transistor pair are directly driven in an inverted manner by the two GPIO ports of the mission-powered microcontroller. The power supply voltage of the complementary pair is the rated voltage of the 100mAh battery, which is 3.0V-3.7V. The half-bridge push-pull drive module and the series resonant branch form a series resonant circuit, and the resonant frequency of the series resonant circuit is equal to the first frequency.

8. The wireless detonator initiation detection system based on magnetic induction through-ground bidirectional communication according to claim 1, characterized in that, The high-sensitivity magnetic induction receiving array consists of multiple hollow induction coils and is configured to receive uplink signals from underground wireless detonators. The high-sensitivity magnetic induction receiving array includes 2×2 arranged 1m×1m square hollow coils, with a center-to-center distance of 2m between each coil; Before coherently accumulating the multiple induced voltage signals, the digital signal processing unit first performs phase alignment and amplitude weighting on the signals of each coil channel, so that the multiple signals are superimposed in phase to obtain array merging gain.

9. The wireless detonator initiation detection system based on magnetic induction through-ground bidirectional communication according to claim 1, characterized in that, The first verification code is an 8-bit random number randomly generated by the ground station at the start of each detonation mission; After entering the verification detonation state, the detonator stores the first verification code in a non-volatile memory and performs detonation only when it receives the confirmation detonation frame containing the same first verification code. If the verification code in the received confirmation detonation frame is inconsistent with the stored first verification code, or if the countdown time window has expired, the detonator refuses to detonate and releases the preparation for detonation state.

10. A wireless detonator initiation detection method based on magnetic induction through-ground two-way communication, characterized in that, Including the following methods: S1: Network Registration The ground station sends a registration frame to each detonator through the downlink magnetic induction channel. After registration, the detonator enters the network to be detonated and sends back a registration confirmation frame in the allocated time slot. S2: Network Detection The ground station polls each detonator through time-division multiplexing. Each detonator sends back a status frame in the corresponding time slot. The ground station determines whether the detonator network meets the detonation conditions based on the sent-back status and marks and removes abnormal detonators. S3: Pre-detonation The ground station sends a pre-detonation frame containing a countdown time window and a first verification code. After the detonator receives and verifies the frame, it enters the pre-detonation state, starts a local countdown, and sends back a pre-detonation confirmation frame in a fixed time slot. S4: Uplink signal coherent accumulation detection The ground station generates a local quadrature carrier signal within the fixed time slot, multiplies the multiple induced voltage signals output by the receiving array with the local quadrature carrier signal, and obtains a baseband complex signal after low-pass filtering. The baseband complex signal is coherently accumulated within a preset integration time window, and the coherent accumulated value is subjected to sliding correlation operation with the locally pre-stored uplink frame preamble reference waveform. When the correlation peak exceeds the noise threshold, it is determined that the pre-detonation confirmation frame has arrived. S5: Detonation Confirmed The ground station sends a confirmation detonation frame containing the same first verification code within the countdown time window. After the detonator verification is passed, the MOS tube is triggered to perform detonation. S6: Abnormal Cancellation If a cancellation frame is received within the countdown window, or if no confirmation detonation frame is received within the timeout period, the detonator will automatically detonate.

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