Underground coal mine radio wave omnidirectional receiving system

Abstract

The invention discloses a coal mine underground radio wave omnidirectional receiving system, which belongs to the technical field of radio wave receiving, and comprises a multi-frequency transmitting module, a high-sensitivity receiving module and a receiving monitoring module, the output end of the multi-frequency transmitting module is connected with the input end of the high-sensitivity receiving module, and the output end of the high-sensitivity receiving module is connected with the receiving monitoring module. The output end of the high-sensitivity receiving module is connected with the input end of the receiving monitoring module, and the output end of the receiving monitoring module is connected with the input end of the data analysis module; according to the invention, the phase-locked loop amplification circuit, the self-adaptive gain control circuit and the DSP digital processing circuit are arranged in the weak signal processing circuit, so that weak analog signals can be well extracted, automatically amplified and then converted into digital signals, the amplification factor can be automatically adjusted according to field conditions, and the signal receiving sensitivity and the signal-to-noise ratio are improved; and a DFT discrete Fourier transform method is adopted in the DSP digital processing circuit, so that the signal processing precision is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of radio wave reception, and in particular relates to an omnidirectional radio wave receiving system in an underground coal mine. Background Art

[0002] Radio wave perspective method, also known as shadow method or pit perspective technology, is a method of detecting underground geological bodies by using the property of good conductive geological bodies to strongly absorb high-frequency electromagnetic waves. Specifically, radio wave perspective method places the transmitter and receiver in two boreholes (tunnels) at a certain distance, and the transmitter transmits electromagnetic waves to the surrounding medium through the antenna, and then the receiver receives the electromagnetic wave signal through the antenna. When electromagnetic waves encounter good conductive geological bodies during underground propagation, they will be strongly absorbed and attenuated, forming shadows. By analyzing and studying these shadows, the location and properties of the geological body can be inferred. In order to receive radio waves well, it is necessary to apply the radio wave receiving system to coal mine underground.

[0003] The Chinese patent discloses (CN116864958A) an omnidirectional radio wave receiving antenna for underground coal mines, with an operating frequency band of 930MHz to 950MHz. It adopts a high dielectric constant flexible dielectric substrate and uses meandering technology to achieve miniaturization of the antenna and reduce the overall size of the device. The application of gradient microstrip lines broadens the working bandwidth of the antenna. Through the antenna array, the superposition principle of the radiation field is used to ensure the gain of the antenna while miniaturizing the antenna. The relatively soft characteristics of the flexible dielectric substrate are used, and the flexible bending of the antenna array is used through HFSS software simulation analysis to change the superposition effect of the radiation field, thereby achieving the adjustment of the area of ​​the received signal. Technical effect: The SMA feeding connector and the easily detachable adjustment rod are used to achieve the technical effect of easy installation and maintenance of the antenna unit. The antenna has a simple overall structure, low cost, easy manufacturing, easy adjustment, light weight, easy installation and maintenance, and a low equipment failure rate. The patent publication number is (CN105445807A) A multi-frequency synchronous radio electromagnetic wave perspective device and method for mining discloses a multi-frequency synchronous radio electromagnetic wave perspective device for mining, which can automatically and synchronously transmit and receive information at multiple frequencies, but it still has problems such as low penetration ability, unstable receiving signal, and poor application effect. In order to solve the above problems, there is an urgent need for an omnidirectional radio wave receiving system for underground coal mines. Summary of the invention

[0004] The purpose of the present invention is to propose an omnidirectional radio wave receiving system for underground coal mines in order to solve the problems that although the current radio wave receiving system can automatically transmit and receive information of multiple frequencies synchronously, it still has low penetration ability, unstable receiving signals, and poor application effect.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a coal mine underground radio wave omnidirectional receiving system, including a multi-frequency transmitting module, a high-sensitivity receiving module and a receiving monitoring module, the output end of the multi-frequency transmitting module is connected to the input end of the high-sensitivity receiving module, the output end of the high-sensitivity receiving module is connected to the input end of the receiving monitoring module, the output end of the receiving monitoring module is connected to the input end of the data analysis module, and the output end of the data analysis module is connected to the input end of the analysis result visualization display module.

[0006] As a further description of the above technical solution:

[0007] The multi-frequency transmission module comprises a radio wave transmission power supply unit, the output end of the radio wave transmission power supply unit is connected to the input end of the radio wave transmission main control module, and the output end of the radio wave transmission main control module is connected to the input end of the transmission power automatic adjustment module.

[0008] As a further description of the above technical solution:

[0009] The output end of the transmission power automatic adjustment module is connected to the input end of the DDS signal generation module, the output end of the DDS signal generation module is connected to the input end of the digital PWM transmission module, and the output end of the digital PWM transmission module is connected to the input end of the LC resonance transmission module.

[0010] As a further description of the above technical solution:

[0011] The transmitting main control module controls the connection between the DDS signal generating module and the digital PWM transmitting module to generate a high-precision transmitting pulse signal. The transmitting power automatic adjustment module is connected to the digital PWM transmitting module to automatically amplify the digital square wave pulse signal output by the DDS signal generating module. The amplified digital square wave signal is transmitted through the LC resonance transmitting module.

[0012] As a further description of the above technical solution:

[0013] The transmitting power automatic adjustment module includes a transmitting current acquisition circuit and a digital DC-DC boost circuit. The transmitting current acquisition circuit is used to detect the transmitting current output by the digital DC-DC boost circuit. The transmitting main control circuit automatically adjusts the transmitting voltage of the digital DC-DC boost circuit according to the detected transmitting current, and amplifies and adjusts the transmitting power to the maximum power of the rated output.

[0014] As a further description of the above technical solution:

[0015] The high-sensitivity receiving module includes a radio wave receiving power supply unit and a weak signal processing module, the output end of the radio wave receiving power supply unit is connected to the input end of the weak signal processing module, the output end of the weak signal processing module is connected to the input end of the signal acquisition circuit module, the output end of the signal acquisition circuit module is connected to the input end of the receiving CPU control module, and the output end of the error data deletion module is connected to the input end of the data reintegration module.

[0016] As a further description of the above technical solution:

[0017] The weak signal processing module includes a phase-locked loop amplification module and an adaptive gain control module, the output end of the phase-locked loop amplification module is connected to the input end of the adaptive gain control module, and the output end of the adaptive gain control module is connected to the input end of the DSP digital processing module.

[0018] As a further description of the above technical solution:

[0019] The weak signal processing module is used to extract weak analog signals, automatically amplify them and then convert them into digital signals. The signal acquisition circuit module uses FPGA timing control and its internal high-speed SRAM storage to perform high-speed data acquisition. The collected data is graphically analyzed by the perspective system program and displayed graphically.

[0020] As a further description of the above technical solution:

[0021] The receiving monitoring module includes a receiving radio wave parameter detection module, the output end of the receiving radio wave parameter detection module is connected to the input end of the receiving radio wave strength detection module, the output end of the receiving radio wave strength detection module is connected to the input end of the data automatic integration module, the output end of the data automatic integration module is connected to the input end of the data automatic recording module, and the output end of the data automatic recording module is connected to the input end of the data automatic uploading module.

[0022] As a further description of the above technical solution:

[0023] The data analysis module includes a received radio wave strength determination module and a received effect evaluation module, the output end of the received radio wave strength determination module is connected to the input end of the received effect evaluation module, the output end of the received effect evaluation module is connected to the input end of the problem self-check module, the output end of the problem self-check module is connected to the input end of the optimization processing strategy generation module, and the output end of the optimization processing strategy generation module is connected to the input end of the re-evaluation module.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. Under the premise of taking into account coal safety requirements and maximizing effective power, the present invention sets a transmission power automatic adjustment module, a DDS signal generating circuit and a digital PWM transmission circuit in the multi-frequency transmission module, and uses multi-frequency transmission technology to achieve accurate matching of different working face widths and coal thicknesses. A weak signal processing circuit and a high-speed signal acquisition circuit are set in the high-sensitivity receiving module. The signal-to-noise ratio is maximized and the ability to capture weak signals is improved by reducing the background noise of the receiver, efficiently extracting weak signals, and fully digital receiving technology. The radio wave perspective penetration distance can be increased to more than 300m, up to 400m, which is very suitable for the internal structure detection of long-distance comprehensive mining working faces in underground mining environments, and is conducive to ensuring safe and efficient production in mines.

[0026] 2. The present invention adopts Class D amplification technology in the transmitting module. The transmitting main control circuit can automatically adjust the transmitting voltage of the digital DC-DC boost circuit according to the detected transmitting current, and amplify the transmitting power to the maximum power of the rated output; a transmitting coil that can match five transmitting frequencies is provided in the LC resonant transmitting antenna, which can emit electromagnetic waves of five different frequencies, so as to facilitate the detection of working surfaces of different widths by using electromagnetic waves of appropriate frequencies.

[0027] 3. The present invention can extract weak analog signals well, automatically amplify them and then convert them into digital signals by setting a phase-locked loop amplifier circuit, an adaptive gain control circuit and a DSP digital processing circuit in the weak signal processing circuit. It can automatically adjust the amplification factor according to the site conditions to improve the sensitivity and signal-to-noise ratio of signal reception. The DFT discrete Fourier transform method is used in the DSP digital processing circuit to greatly improve the signal processing accuracy.

[0028] 4. The present invention is equipped with a receiving monitoring module, a data analysis module and an analysis result visualization display module, so that it can monitor and evaluate the reception of radio waves after the high-sensitivity receiving module, thereby performing self-checking of problems, and can automatically generate processing strategies to quickly handle problems. After processing, it will re-evaluate until the evaluation results are qualified, thereby effectively ensuring the stability of the system and the reception effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure is a schematic diagram of the module structure of an omnidirectional radio wave receiving system in underground coal mines.

[0030] Figure 2 The present invention is a schematic diagram of the submodule structure of a multi-frequency transmitting module in an omnidirectional radio wave receiving system in underground coal mines.

[0031] Figure 3 The diagram is a schematic diagram of the submodule structure of a high-sensitivity receiving module in an omnidirectional radio wave receiving system in underground coal mines.

[0032] Figure 4 The present invention is a schematic diagram of the submodule structure of a receiving monitoring module in an omnidirectional radio wave receiving system in an underground coal mine.

[0033] Figure 5 The present invention is a schematic diagram of the submodule structure of a data analysis module in an omnidirectional radio wave receiving system in underground coal mines.

[0034] Figure 6 The present invention is a schematic diagram of the submodule structure of a weak signal processing module in an omnidirectional radio wave receiving system in underground coal mines.

[0035] Legend:

[0036] 1. Multi-frequency transmission module; 2. High-sensitivity receiving module; 201. Weak signal processing module; 3. Receiving monitoring module; 4. Data analysis module. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] See also Figure 1-Figure 6 The present invention provides a technical solution: an omnidirectional radio wave receiving system for underground coal mines, comprising multi-frequency transmitting modules 1, 2 and a receiving monitoring module 3, wherein the output end of the multi-frequency transmitting module 1 is connected to the input end of the high-sensitivity receiving module 2, the output end of the high-sensitivity receiving module 2 is connected to the input end of the receiving monitoring module 3, the output end of the receiving monitoring module 3 is connected to the input end of the data analysis module 4, and the output end of the data analysis module 4 is connected to the input end of the analysis result visualization display module.

[0040] The multi-frequency transmission module 1 includes a radio wave transmission power supply unit, the output end of the radio wave transmission power supply unit is connected to the input end of the radio wave transmission main control module, the output end of the radio wave transmission main control module is connected to the input end of the transmission power automatic adjustment module, the output end of the transmission power automatic adjustment module is connected to the input end of the DDS signal generation module, the output end of the DDS signal generation module is connected to the input end of the digital PWM transmission module, and the output end of the digital PWM transmission module is connected to the input end of the LC resonance transmission module.

[0041] The wireless transmission main control module controls the connection between the DDS signal generating module and the digital PWM transmitting module to generate a high-precision transmitting pulse signal. The transmitting power automatic adjustment module is connected to the digital PWM transmitting module to automatically amplify the digital square wave pulse signal output by the DDS signal generating module. The amplified digital square wave signal is transmitted through the LC resonance transmitting module. The transmitting power automatic adjustment module includes a transmitting current acquisition circuit and a digital DC-DC boost circuit. The transmitting current acquisition circuit is used to detect the transmitting current output by the digital DC-DC boost circuit. The transmitting main control circuit automatically adjusts the transmitting voltage of the digital DC-DC boost circuit according to the detected transmitting current, and amplifies and adjusts the transmitting power to the maximum power of the rated output.

[0042] The high-sensitivity receiving module 2 includes two key parts, namely, the radio wave receiving power supply unit and the weak signal processing module 201. First, the radio wave receiving power supply unit is the energy supply source of the entire receiving module, and its output end is closely connected to the input end of the weak signal processing module 201. This connection ensures that the weak signal processing module 201 can obtain continuous and stable power support, so as to carry out the processing of weak signals normally.

[0043] After receiving the electric energy provided by the radio wave receiving power supply unit, the weak signal processing module 201 starts to perform a series of processing operations on the received weak radio wave signal. After the processing is completed, its output end is connected to the input end of the signal acquisition circuit module, and the signal after preliminary processing is transmitted to the signal acquisition circuit module. The signal acquisition circuit module can accurately collect data on the input signal by virtue of its own circuit design and function, and the collected data covers various characteristics and related information of the signal.

[0044] Next, the output of the signal acquisition circuit module is connected to the input of the receiving CPU control module. The receiving CPU control module will comprehensively coordinate and precisely control the data collected by the signal acquisition circuit module. It can analyze the validity and accuracy of the data, and further screen and process the data according to the preset programs and algorithms to ensure that the data meets the requirements of subsequent operations.

[0045] In addition, during the data processing process, an error data deletion module is also provided. This module will detect the data processed by the receiving CPU control module and identify the error data therein. Once the error data is found, the error data deletion module will delete it to improve the quality of the data. The output end of the error data deletion module is connected to the input end of the data reintegration module. The data reintegration module will reorganize and combine the remaining data after the error data is deleted to make it more orderly and complete, so as to facilitate subsequent data transmission, analysis and application operations, thereby realizing high-sensitivity reception and accurate processing of radio waves in coal mines, and meeting the needs of the entire system for high-quality data.

[0046] The weak signal processing module 201 includes a phase-locked loop amplifier module and an adaptive gain control module. The output end of the phase-locked loop amplifier module is connected to the input end of the adaptive gain control module, and the output end of the adaptive gain control module is connected to the input end of the DSP digital processing module. The weak signal processing module is used to extract and automatically amplify the weak analog signal and then convert it into a digital signal. The signal acquisition circuit module uses FPGA timing control and its internal high-speed SRAM storage to perform high-speed data acquisition. The collected data is graphically analyzed by the perspective system program and displayed in graphics.

[0047] The receiving monitoring module 3 includes a receiving radio wave parameter detection module, the output end of the receiving radio wave parameter detection module is connected to the input end of the receiving radio wave strength detection module, the output end of the receiving radio wave strength detection module is connected to the input end of the data automatic integration module, the output end of the data automatic integration module is connected to the input end of the data automatic recording module, and the output end of the data automatic recording module is connected to the input end of the data automatic uploading module.

[0048] The data analysis module 4 includes a received radio wave strength determination module and a received effect evaluation module, the output end of the received radio wave strength determination module is connected to the input end of the received effect evaluation module, the output end of the received effect evaluation module is connected to the input end of the problem self-check module, the output end of the problem self-check module is connected to the input end of the optimization processing strategy generation module, and the output end of the optimization processing strategy generation module is connected to the input end of the re-evaluation module.

[0049] In this embodiment, under the premise of taking into account coal safety requirements and maximizing effective power, an automatic transmission power adjustment circuit, a DDS signal generating circuit and a digital PWM transmission circuit are set in the multi-frequency transmission module, and multi-frequency transmission technology is used to achieve accurate matching of different working face widths and coal thicknesses. A weak signal processing circuit and a high-speed signal acquisition circuit are set in the high-sensitivity receiving module. The signal-to-noise ratio is maximized and the ability to capture weak signals is improved by reducing the receiver background noise, efficient weak signal extraction technology, and fully digital receiving technology. The radio wave penetration distance can be increased to more than 300m, up to 400m, which is very suitable for internal structure detection of long-distance comprehensive mining working faces in underground mining environments, and is conducive to ensuring safe and efficient production in mines.

[0050] In the embodiment, it should be noted that:

[0051] The LC resonance transmitting module includes transmitting coils matching five transmitting frequencies of 965KHz, 500KHz, 365KHz, 158KHz and 88KHz; the phase-locked loop amplifying circuit includes a preamplifying circuit, a frequency selection filtering circuit, a phase-locked loop, a phase shifter, a mixing multiplier, a low-pass filter and a DC amplifying circuit; the weak signal processing module is provided with a discrete Fourier transform signal extraction processing module; during detection, the multi-frequency transmitting module and the high-sensitivity receiving module are arranged one-to-one; or one-to-many, arranged in a fixed-point transmitting and multiple-point receiving mode or a one-transmitting and multiple-receiving mode; the multi-frequency transmitting module and the high-sensitivity receiving module also include a memory, an LCD display circuit, a communication circuit, a key input circuit and a USB circuit.

[0052] Example 2

[0053] See also Figure 1A coal mine underground radio wave omnidirectional receiving system, comprising a multi-frequency transmitting module 1 and a high-sensitivity receiving module 2, wherein the multi-frequency transmitting module comprises a transmitting power supply, a transmitting main control circuit, a transmitting power automatic adjustment circuit, a DDS signal generating circuit, a digital PWM transmitting circuit and an LC resonant transmitting antenna, wherein the transmitting main control circuit controls the connection between the DDS signal generating circuit and the digital PWM transmitting circuit to generate a high-precision transmitting pulse signal, wherein the transmitting power automatic adjustment circuit is connected to the digital PWM transmitting circuit to automatically amplify the digital square wave pulse signal output by the DDS signal generating circuit, and the amplified digital square wave signal is transmitted through the LC resonant transmitting antenna, wherein the LC resonant transmitting antenna includes The invention comprises a transmitting coil matched with five transmitting frequencies of 965KHz, 500KHz, 365KHz, 158KHz and 88KHz; the high-sensitivity receiving module comprises a receiving power supply, a weak signal processing circuit, a signal acquisition circuit and a receiving CPU control circuit; the weak signal processing circuit comprises a phase-locked loop amplifying circuit, an adaptive gain control circuit and a DSP digital processing circuit; the weak signal processing circuit is used to extract and automatically amplify the weak analog signal and then convert it into a digital signal; the signal acquisition circuit utilizes FPGA timing control and its internal high-speed SRAM storage to perform high-speed data acquisition; the acquired data is graphically analyzed by the perspective system program and displayed graphically.

[0054] The multi-frequency transmitting module of this system adopts a digital Class-D amplifier structure, and uses an extremely high-frequency conversion switch circuit to amplify the signal. It has the advantages of high efficiency and small size. It can efficiently amplify the small digital square wave signal generated by DDS, thereby realizing the first-level amplification of the digital square wave signal. The amplified digital square wave signal is sent to the LC resonant transmitting antenna. Since the LC resonant circuit has the characteristics of frequency selection and amplification, the harmonics of the digital square wave signal of a specific frequency will be filtered out after entering, only the fundamental frequency part will be retained and it will be amplified twice, thereby realizing the transmission of wireless electromagnetic wave signals.

[0055] The multi-frequency transmission module and high-sensitivity receiving module also include a memory, an LCD display circuit, a communication circuit, a key input circuit and a USB circuit. The transmitting main control circuit and the receiving CPU control circuit adopt the Intel Cyclone10 FPGA embedded system platform, which is the core of the control and processing of the entire instrument. Through the SOPC technology, the soft-core CPU and the controller of the peripheral module are embedded inside to realize the precise control of the dead zone of the PWM transmission circuit, control the DDS signal generation circuit to generate a high-precision transmission pulse frequency, as well as human-computer interaction, data acquisition, communication and other functions.

[0056] From the perspective of the factors affecting the propagation of electromagnetic waves, the electromagnetic waves emitted by the transmitter, in addition to penetrating the working surface, must also overcome the attenuation of electromagnetic wave signals by water vapor molecules, wet lanes, and dust. In addition, the surrounding anchor rods, anchor nets and other metals will produce mutual inductance with the transmitting antenna, which also has an attenuation effect on the electromagnetic waves and thus affects the transmission power. The metal objects around different transmitting points are also different, so the transmitter needs to automatically adjust the transmission power according to the surrounding environment to output the maximum power. The transmission power automatic adjustment circuit includes a transmission current acquisition circuit and a digital DC-DC boost circuit. The transmission current acquisition circuit is used to detect the transmission current output by the digital DC-DC boost circuit. The transmission main control circuit automatically adjusts the transmission voltage of the digital DC-DC boost circuit according to the detected transmission current, and amplifies the transmission power to the rated maximum output power. When in use, when the shape of the transmitting antenna is fixed, the system detects that the transmission power has not reached the maximum power, the transmission main control circuit will adjust the transmission voltage (U), and the transmission current acquisition circuit will detect the transmission current (I) at this time, and automatically adjust the power according to the P=UI formula until the transmission power reaches the maximum power.

[0057] Since the signal power of the multi-frequency transmitting module is limited by coal security, when the electromagnetic wave signal of the transmitting lane penetrates the working face, most of its energy is absorbed, scattered, and emitted by the medium in the working face, and the remaining energy that can reach the receiving lane is negligible. Its voltage amplitude is basically at the uV level. Compared with the mV level interference noise in the lane, its signal-to-noise ratio is very low. Therefore, in order to achieve detection accuracy, it is necessary to effectively extract the useful weak signal from the background noise of strong interference, and at the same time, it is necessary to reduce the background noise of the machine. The phase-locked loop amplifier circuit in the weak signal processing circuit includes a preamplifier circuit, a frequency selection filter circuit, a phase-locked loop, a phase shifter, a mixer multiplier, a low-pass filter and a DC amplifier circuit. A discrete Fourier transform signal extraction processing module is provided in the weak signal processing circuit. The adaptive gain control circuit can automatically adjust the magnification according to the field conditions to improve the sensitivity and signal-to-noise ratio of the instrument. The signal acquisition circuit uses FPGA timing control and its internal high-speed SRAM storage to perform high-speed acquisition at a rate of 20M, which meets the effective acquisition of higher frequency signals of radio waves and large-capacity sample data.

[0058] Since the useful signal received by the receiver is weak and the surrounding background interference noise is strong, the signal-to-noise ratio of the signal is very low. It is basically impossible to extract the effective received signal in the time domain, so it is necessary to switch to the frequency domain for processing. The spectrum of the periodic signal represents the three parameters of frequency, amplitude and initial phase of all cosine signals of different frequencies contained in this periodic signal. By converting the time domain signal to the frequency domain through Fourier transform technology, you can see the frequency, phase, amplitude, energy and other information of each harmonic. In the frequency domain, select the known transmitting frequency and the amplitude and phase of its corresponding frequency, and collect a large amount of data according to a fixed number of cycles to superimpose multiple cycles of data and calculate the average to reduce the interference of random noise, thereby realizing the extraction of useful signals.

[0059] During detection, the multi-frequency transmitting module and the high-sensitivity receiving module are arranged one-to-one, or one-to-many, and arranged in a fixed-point transmitting and multiple-point receiving mode or a one-transmitting and multiple-receiving mode.

[0060] When using the one-to-one fixed-point method for observation, the position of the multi-frequency transmitting module is relatively fixed within a certain period of time, and the high-sensitivity receiving module observes its field strength value point by point within a certain range, that is, fixed-point transmission and multi-point reception, also known as the fixed-point intersection method. When the length of the working face is not large, the shape is irregular, and the artificial interference body can be excluded, the fixed-point method can be selected for observation. With this observation method, the working face can be fully covered twice without leaving a blind spot, and the two-lane fixed-point intersection method can be used to specifically determine the nature, spatial position and size of the geological anomaly body according to the radio wave perspective comprehensive curve diagram, which is convenient for purposeful drilling verification, with low investment and quick results. The fixed-point method is a commonly used observation method underground. Generally, the transmitting point distance is 30 to 50 meters, and the receiving point distance is 5 to 10 meters. For each transmitting point, the receiver can observe 11 to 21 points accordingly.

[0061] When one-to-many settings are set, one transmitter corresponds to multiple receivers. "One transmitter, multiple receivers" is applied to fixed-point construction. Generally, the transmission point distance is 30 to 50 meters, and the reception point distance is 5 to 10 meters. For each transmission point, the receiver can observe 11 to 21 points accordingly; generally, the tunnel can simultaneously receive at a distance of 100 to 200 meters.

[0062] Take underground interference elimination measures during detection: To ensure the accuracy of received data and improve detection accuracy, the power cables in the working face chute and the inner return air chute must be shut down in advance; Transmission requirements: The transmitting point should be as far away as possible from the interference area (such as large electrical appliances, iron equipment, and dense metal supports) to avoid the formation of large shadow areas, which is not conducive to the smooth progress of work and the effective use of data.

[0063] Therefore, after the working face is excavated and penetrated, before the mining equipment is installed, it is most reasonable and beneficial to conduct radio wave fluoroscopy during the interval between the dismantling and installation of equipment, so that radio wave fluoroscopy and production can be carried out at the same time. Conducting radio wave fluoroscopy at this time reduces a lot of tedious preparation and auxiliary work, and provides a good environment for radio wave fluoroscopy work, achieving good results.

[0064] In this embodiment, by adopting Class D amplification technology in the transmitting module, the transmitting main control circuit can automatically adjust the transmitting voltage of the digital DC-DC boost circuit according to the detected transmitting current, and amplify the transmitting power to the maximum power of the rated output; a transmitting coil that can match five transmitting frequencies is provided in the LC resonant transmitting antenna, which can emit electromagnetic waves of five different frequencies, so as to facilitate the detection of working surfaces of different widths by using electromagnetic waves of appropriate frequencies.

[0065] In the embodiment, the models of the multi-frequency transmitting module 1 are SFP-GE-SX-MM850-A and H-8125NL-S.

[0066] The model of high-sensitivity receiving module 2 is RX480;

[0067] The model of the receiving monitoring module 3 is 315M / 411M.

[0068] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An omnidirectional radio wave receiving system for underground coal mines, comprising a multi-frequency transmitting module (1), a high-sensitivity receiving module (2) and a receiving monitoring module (3), characterized in that: The output end of the multi-frequency transmission module (1) is connected to the input end of the high-sensitivity receiving module (2), the output end of the high-sensitivity receiving module (2) is connected to the input end of the receiving monitoring module (3), the output end of the receiving monitoring module (3) is connected to the input end of the data analysis module (4), and the output end of the data analysis module (4) is connected to the input end of the analysis result visualization display module.

2. The coal mine underground radio wave omnidirectional receiving system according to claim 1, characterized in that: The multi-frequency transmission module (1) comprises a radio wave transmission power supply unit, the output end of the radio wave transmission power supply unit is connected to the input end of the radio wave transmission main control module, and the output end of the radio wave transmission main control module is connected to the input end of the transmission power automatic adjustment module.

3. The coal mine underground radio wave omnidirectional receiving system according to claim 2, characterized in that: The output end of the transmission power automatic adjustment module is connected to the input end of the DDS signal generation module, the output end of the DDS signal generation module is connected to the input end of the digital PWM transmission module, and the output end of the digital PWM transmission module is connected to the input end of the LC resonance transmission module.

4. The coal mine underground radio wave omnidirectional receiving system according to claim 3, characterized in that: The transmitting main control module controls the connection between the DDS signal generating module and the digital PWM transmitting module to generate a high-precision transmitting pulse signal. The transmitting power automatic adjustment module is connected to the digital PWM transmitting module to automatically amplify the digital square wave pulse signal output by the DDS signal generating module. The amplified digital square wave signal is transmitted through the LC resonance transmitting module.

5. The coal mine underground radio wave omnidirectional receiving system according to claim 4, characterized in that: The transmitting power automatic adjustment module includes a transmitting current acquisition circuit and a digital DC-DC boost circuit. The transmitting current acquisition circuit is used to detect the transmitting current output by the digital DC-DC boost circuit. The transmitting main control circuit automatically adjusts the transmitting voltage of the digital DC-DC boost circuit according to the detected transmitting current, and amplifies and adjusts the transmitting power to the maximum power of the rated output.

6. The coal mine underground radio wave omnidirectional receiving system according to claim 5, characterized in that: The high-sensitivity receiving module (2) comprises a radio wave receiving power supply unit and a weak signal processing module (201), the output end of the radio wave receiving power supply unit is connected to the input end of the weak signal processing module (201), the output end of the weak signal processing module (201) is connected to the input end of a signal acquisition circuit module, the output end of the signal acquisition circuit module is connected to the input end of a receiving CPU control module, and the output end of the error data deletion module is connected to the input end of a data reintegration module.

7. The coal mine underground radio wave omnidirectional receiving system according to claim 6, characterized in that: The weak signal processing module (201) comprises a phase-locked loop amplification module and an adaptive gain control module, the output end of the phase-locked loop amplification module is connected to the input end of the adaptive gain control module, and the output end of the adaptive gain control module is connected to the input end of the DSP digital processing module.

8. The coal mine underground radio wave omnidirectional receiving system according to claim 7, characterized in that: The weak signal processing module is used to extract weak analog signals, automatically amplify them and then convert them into digital signals. The signal acquisition circuit module uses FPGA timing control and its internal high-speed SRAM storage to perform high-speed data acquisition. The collected data is graphically analyzed by the perspective system program and displayed graphically.

9. The coal mine underground radio wave omnidirectional receiving system according to claim 8, characterized in that: The receiving monitoring module (3) comprises a receiving radio wave parameter detection module, the output end of the receiving radio wave parameter detection module is connected to the input end of the receiving radio wave strength detection module, the output end of the receiving radio wave strength detection module is connected to the input end of the automatic data integration module, the output end of the automatic data integration module is connected to the input end of the automatic data recording module, and the output end of the automatic data recording module is connected to the input end of the automatic data uploading module.

10. The coal mine underground radio wave omnidirectional receiving system according to claim 9, characterized in that: The data analysis module (4) comprises a received radio wave strength determination module and a received effect evaluation module, wherein the output end of the received radio wave strength determination module is connected to the input end of the received effect evaluation module, the output end of the received effect evaluation module is connected to the input end of the problem self-checking module, the output end of the problem self-checking module is connected to the input end of the optimized processing strategy generation module, and the output end of the optimized processing strategy generation module is connected to the input end of the re-evaluation module.

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