A method and system for limiting the radiation of radio electromagnetic waves to human body in underground mines

Abstract

A method and system for limiting the radiation of radio electromagnetic waves to the human body in underground mines include: receiving radio electromagnetic waves, fixing the attenuation signal amplitude, performing low-pass filtering, mixing the wave generated by a frequency generator with a new frequency signal after frequency multiplication by a phase-locked loop and low-pass filtering; amplifying the amplitude of the new frequency signal by an intermediate frequency, filtering out the intermediate frequency signal; obtaining the envelope of the original information signal, and obtaining the modulation mode, frequency, and bandwidth; if the radio electromagnetic wave radiation intensity is greater than a set value, locking the frequency band, analyzing the channel access mechanism, capturing the frame structure, locating the wireless protocol according to the frame structure, sending a command to a base station core board, and the base station core board changes the transmission power according to the command; in the above method and system, if the radio electromagnetic wave radiation intensity is greater than a set value, by analyzing the channel access mechanism and locating the wireless protocol according to the frame structure, a command is sent to the base station core board to control the transmission power, adjust the transmission power, and limit the radiation of the radio electromagnetic wave to below the radiation limit.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic radiation protection, and in particular to a method and system for limiting the radiation of wireless electromagnetic waves to human body in underground mines. Background Art

[0002] The underground mine is a complex and changeable environment, facing many wireless communication systems. The underground communication systems are mainly based on WiFi, UWB, 4G and 5G, etc., and are also accompanied by the potential hazards of various wireless radiation. The "Electromagnetic Radiation Protection Regulations" (GB8702-88) stipulates that the power density standard limit of equipment operating in the 30MHz-3GHz frequency band is 40μW / cm 2 , that is, the radiation limit is 0.4W / m 2 This standard aims to limit the potential harm of electromagnetic radiation to the environment and human body. The maximum instantaneous radiation of most wireless devices under normal working conditions is usually 0.2W / m 2 The radiation level is even lower when in standby mode, at 0.01W / m 2 These values ​​are far lower than the national radiation limits. However, the base station works underground for a long time under natural conditions, and the reliability of equipment radiation cannot be ensured. There is often a lack of monitoring and control in this area to avoid the potential harm of wireless radiation to the health of underground workers. There is an urgent need for a mine detection and control system to adjust the radiation intensity of base stations in underground construction, operation and maintenance, mining and other places. Summary of the invention

[0003] Based on this, it is necessary to provide a method for limiting the radiation of radio electromagnetic waves to the human body in underground mines which can improve performance.

[0004] At the same time, a system for limiting the radiation of radio electromagnetic waves to human body in underground mines is provided, which can improve the performance.

[0005] A method for limiting the radiation of radio electromagnetic waves to human body in underground mines, comprising:

[0006] Fixed amplitude: Receive radio electromagnetic waves and fix the attenuation signal amplitude;

[0007] Low-pass filtering: Low-pass filtering is performed through a low-pass filter;

[0008] Mixing: The wave generated by the frequency generator is multiplied by the phase-locked loop and mixed with the signal after low-pass filtering to produce a new frequency signal;

[0009] Intermediate frequency filtering: amplify the new frequency signal through the intermediate frequency, and filter out the intermediate frequency signal through the intermediate frequency filter;

[0010] Detection: The envelope of the original information signal is obtained through the detector to obtain the modulation mode, frequency, and bandwidth;

[0011] Analysis: Calculate the radiation intensity of the radio electromagnetic wave. If the radiation intensity of the radio electromagnetic wave is greater than the set value, lock the frequency band and conduct analysis. First, analyze the media access control layer through the MAC characteristics in the media control layer, analyze the channel access mechanism, capture the frame structure, locate the wireless protocol according to the frame structure, and send commands to the base station core board according to the wireless protocol and power of the radio electromagnetic wave;

[0012] Change power: The base station core board changes the transmission power of the corresponding wireless protocol according to the command.

[0013] In a preferred embodiment, in the analysis step, the throughput and delay time of the transmission data are collected through carrier sense multiple access to determine whether the access mechanism is a random access mechanism or a controlled access mechanism.

[0014] In a preferred embodiment, in the analysis step, data is first collected for a fixed period of 8-15 minutes, and the statistical throughput is between 1kbps and 1000kbps, and the size of each data packet is consistent, and the interval delay time from the first data packet to the second data packet of the same type is between 10ms and 1000ms, which belongs to the controlled access mechanism; the throughput is between 1kbps and 1000Mbps, the size of each data packet is inconsistent, and the interval delay time from the first data packet to the second data packet of the same type is irregular, which belongs to the random access mechanism.

[0015] In a preferred embodiment, in the analysis, the header, data part and tail are analyzed to locate the wireless protocol according to the characteristics of the frame structure.

[0016] In a preferred embodiment, during the analysis, locating the wireless protocol includes:

[0017] Identify frame type: Determine the frame type by looking at the protocol type field in the frame header;

[0018] Check the frame header fields: Analyze each field in the frame header, including one or more of the source address, destination address, frame length, and protocol type.

[0019] Data analysis part: determine the content, format and size of the data based on the frame header information;

[0020] Verify frame trailer checksum: Use the checksum in the frame trailer to verify data integrity.

[0021] In a preferred embodiment, in the fixed amplitude step, a 5W coaxial RF attenuator with a use range of 0-6GHz is used to fix the attenuation to 10dB, and in the low-pass filtering step, the low-pass filter filters out the second harmonics of 2.4GHz, 1.8GHz and 2.7GHz.

[0022] In a preferred embodiment, in the mixing step, the frequency generator generates a wave with a frequency of 20Mhz, a frequency stability of ±2.5ppm, and a phase noise level below -140dBc / Hz; during mixing, the mixer multiplies two electrical signals of different frequencies to generate a new frequency signal, the noise coefficient of the mixer is less than 15dB, the frequency conversion loss is between 5dB and 8dB, and the isolation is above 30dB.

[0023] In a preferred embodiment, in the intermediate frequency filtering step, the filtered signal is an intermediate frequency signal of 2.4 GHz to 4.2 GHz selected by the passband, and waves outside the range of 2.4 GHz to 4.2 GHz are filtered out.

[0024] In a preferred embodiment, in the analysis step, the frequency band is locked within the range of 2.414 GHz to 4.2 GHz, and frequency analysis is performed to obtain the frequency of the signal received by the antenna, and the signal protocol is obtained based on the signal frequency.

[0025] A system for limiting the radiation of radio electromagnetic waves to the human body in underground mines, comprising:

[0026] Fixed amplitude module: receives radio electromagnetic waves and fixes the attenuation signal amplitude;

[0027] Low-pass filtering module: low-pass filtering is performed through a low-pass filter;

[0028] Mixing module: The wave generated by the frequency generator is multiplied by the phase-locked loop and mixed with the signal after low-pass filtering to produce a new frequency signal;

[0029] Intermediate frequency filtering module: amplifies the new frequency signal through the intermediate frequency, and filters out the intermediate frequency signal through the intermediate frequency filter;

[0030] Detection module: obtains the envelope of the original information signal through the detector to obtain the modulation mode, frequency and bandwidth;

[0031] Analysis module: Calculates the radiation intensity of radio electromagnetic waves. If the radiation intensity of radio electromagnetic waves is greater than the set value, locks the frequency band and performs analysis. First, the media access control layer analyzes the MAC characteristics in the media control layer, analyzes the channel access mechanism, captures the frame structure, locates the wireless protocol according to the frame structure, and sends commands to the base station core board according to the wireless protocol and power of the radio electromagnetic waves.

[0032] Change power module: The base station core board changes the transmission power of the corresponding wireless protocol according to the command

[0033] The above-mentioned method and system for limiting the radiation of radio electromagnetic waves to the human body in underground mines, after receiving the radio electromagnetic waves and undergoing a series of processing, calculates the radiation intensity of the radio electromagnetic waves. If the radiation intensity of the radio electromagnetic waves is greater than the set value, it is analyzed after locking the frequency band, analyzing the channel access mechanism of the signal, and locating the wireless protocol according to the frame structure, thereby issuing a command to the base station core board to control the transmission power, thereby adjusting the transmission power and limiting the radiation of the radio electromagnetic waves to below the radiation limit. The detection and control system in the mine adjusts and controls the radiation intensity of the base stations in underground construction, operation and maintenance, mining and other places. Electromagnetic radiation control is carried out in mine environments such as closed tunnels and construction sites to eliminate the potential hazards of wireless radiation and protect safety.

[0034] The high-frequency modulated signal received by the antenna is first filtered to remove the useless part, and then mixed to obtain an intermediate frequency signal (down-conversion). The detector then extracts the low-frequency analog signal with information (such as audio, data, etc.) from the intermediate frequency signal, and then digitizes the low-frequency analog signal. The digitized waveform is processed and analyzed by the chip. Mixing is to add the collected signal (low-pass filter filtered signal) and the local oscillator signal (reference signal) (a spectrum shifting process). Mixing is to reduce the frequency of the signal, that is, to obtain an intermediate frequency signal; the local oscillator signal can be generated by an oscillator, and the frequency can be fixed by itself, which is a reference signal. The signal after mixing is generally weak, and the role of intermediate frequency amplification is to amplify this signal so that its amplitude becomes acceptable to the subsequent intermediate frequency filter. The intermediate frequency filter is used to filter out nonlinear spurious and ensure the linearity of the pre-amplifier circuit. Detection is to be able to separate the information signal (the original information part of the modulated signal collected by the antenna) from the modulated signal, which is a demodulation process. Frequency analysis is to digitize the detected low-frequency analog signal first, then determine whether it is desirable, and give the useful signal to the processing module such as MCU for processing.

[0035] The present invention will provide more powerful support for mine safety production and miners' health with greater intelligence, energy saving and efficiency. The present invention relates to the recognition and reverse control gain technology of underground radio protocols in mines, and the method can be applied to closed tunnels and construction sites in underground mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a partial flow chart of a method for limiting the radiation of radio electromagnetic waves to the human body in underground mines according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] like Figure 1 As shown, a method for limiting the radiation of radio electromagnetic waves to the human body in a mine in a preferred embodiment of the present invention comprises:

[0038] Step S101, fixing the amplitude: the antenna receives the radio electromagnetic wave, and fixes the attenuated signal amplitude after attenuating the signal through the attenuator;

[0039] Step S103, low-pass filtering: low-pass filtering is performed through a low-pass filter;

[0040] Step S105, frequency mixing: the wave generated by the frequency generator is frequency-multiplied by a phase-locked loop and mixed with the signal after low-pass filtering to produce a new frequency signal;

[0041] Step S107, intermediate frequency filtering: amplify the new frequency signal by intermediate frequency, and filter it by intermediate frequency filter to obtain intermediate frequency signal;

[0042] Step S109, detection: obtaining the envelope of the original information signal through an envelope detector to obtain the modulation mode, frequency, and bandwidth;

[0043] Step S111, analysis: calculate the radiation intensity of the radio electromagnetic wave. If the radiation intensity of the radio electromagnetic wave is greater than the set value, lock the frequency band and perform analysis. First, analyze the media access control layer through the MAC characteristics in the media control layer, analyze the access mechanism of the channel, capture the frame structure, locate the wireless protocol according to the frame structure, and send a command to the base station core board according to the wireless protocol and power of the radio electromagnetic wave;

[0044] Step S113, changing power: the base station core board changes the transmission power of the corresponding wireless protocol according to the command.

[0045] Further, preferably, in the analysis step of this embodiment, the throughput and delay time of the transmission data are collected through carrier sense multiple access to determine whether the access mechanism is a random access mechanism or a controlled access mechanism.

[0046] Furthermore, in the analysis step of this embodiment, data is first collected for a fixed period of 8-15 minutes, and the statistical throughput is between 1kbps and 1000kbps, and the size of each data packet is consistent, and the interval delay time from the first data packet to the second data packet of the same type is between 10ms and 1000ms, which belongs to the controlled access mechanism; the throughput is between 1kbps and 1000Mbps and the size of each data packet is inconsistent, and the interval delay time from the first data packet to the second data packet of the same type is irregular, which belongs to the random access mechanism.

[0047] Further, preferably, in the analysis step of this embodiment, data is first collected for a fixed period of 10 minutes, and the statistical throughput is between 1kbps and 1000kbps, and the size of each data packet is consistent, and the interval delay time from the first data packet to the second data packet of the same type is between 10ms and 1000ms, which belongs to the controlled access mechanism; the throughput is between 1kbps and 1000Mbps, the size of each data packet is inconsistent, and the interval delay time from the first data packet to the second data packet of the same type is irregular, which belongs to the random access mechanism.

[0048] The present invention can also analyze the access mechanism of the channel through access mechanisms such as conflict avoidance and time slot polling.

[0049] Furthermore, in the analysis step of this embodiment, according to the characteristics of the frame structure, the header, i.e., the frame header, the data part, and the tail, i.e., the frame tail, are analyzed to locate the wireless protocol.

[0050] Further, preferably, in the analysis process of this embodiment, the positioning wireless protocol includes:

[0051] Identify the frame type: Determine the frame type by looking at the protocol type field in the frame header; such as Ethernet frame, IP datagram, TCP segment, or UDP datagram.

[0052] Check the frame header fields: Analyze the various fields in the frame header, including one or more of the source address, destination address, frame length, and protocol type; these fields provide important information about the source and destination of the frame, the size of the frame, and the protocol used.

[0053] Analyze the data part: determine the content, format, and size of the data based on the frame header information; for some protocols, such as TCP and UDP, the data part may also contain additional metadata, such as port number, sequence number, acknowledgment number, and window size.

[0054] Verify the frame trailer checksum: Use the checksum in the frame trailer to verify the integrity of the data. If errors are found, you may need to request a retransmission or take other corrective action.

[0055] Specifically analyze the characteristics of the wireless protocol such as the preamble, frame start delimiter (SFD), destination MAC address, source MAC address, type / length field, data part and frame check sequence (FCS).

[0056] For example, the frame structure of the UWB protocol mainly includes:

[0057] Synchronisation header (SHR): SHR is located at the beginning of the data frame and is used to help the receiver detect the data packet and perform related receiver algorithm processing, such as AGC setting, antenna diversity selection, timing acquisition, coarse and fine frequency recovery, data packet frame synchronization, channel evaluation and edge signal triggering. SHR consists of two parts: preamble and start frame delimiter (SFD). The preamble consists of a series of repeated pulse trains and is used for synchronization and channel estimation. SFD is used to indicate the end of the preamble and the beginning of the physical layer header (PHR).

[0058] Physical layer header (PHR, PHY header): PHR follows SHR and contains 19 bits. It uses BPM-BPSK for modulation and demodulation. PHR contains multiple fields, such as data rate field (indicating the data rate of the received PDU), frame length field (indicating the number of octets in the PDU that the MAC sublayer currently requests PHY to transmit), ranging packet bit (set to 1 if the current frame is a ranging frame), etc.

[0059] Physical Data Unit (PDU): PDU is the part of the data frame used to transmit actual data, which follows the PHR. In UWB communication, PDU may contain multiple types of data, such as key application protocol data unit (APDU). These data units are used to implement specific communication functions, such as key exchange, data encryption, etc.

[0060] Checksum: used to detect errors in received data and correct them.

[0061] The frame structure of the 5G protocol mainly includes:

[0062] Subframe: Each radio frame contains 10 subframes, and each subframe is 1ms long. Same as 4G LTE.

[0063] Time slot: Each subframe can contain multiple time slots, and the number of time slots depends on the subcarrier spacing. 5G NR defines a variety of subcarrier spacings, ranging from 15kHz to 240kHz (specifically 2^μ×15kHz, μ is an integer). As the subcarrier spacing increases, the length of the time slot will decrease accordingly.

[0064] OFDM symbol: In each time slot, a fixed number of OFDM symbols are contained. In the case of a normal cyclic prefix (CP), each time slot contains 14 OFDM symbols. If an extended CP is used, the number of OFDM symbols will be reduced accordingly.

[0065] Such as a. Preamble and SFD, used for synchronization and identification of the start of the frame; b. Destination MAC address and source MAC address, indicating the receiver and sender of the frame respectively; c. Type / length field: indicates whether the content of the data part is an IP datagram or other types of data, or the length of the data part; d. Data part: contains the actual data content of the transmission. e. FCS: used for error detection and correction.

[0066] The frame structure of the WIFI protocol mainly includes:

[0067] Frame Control: This is the beginning of the MAC frame, with a length of 2 bytes. It contains multiple subfields, which are used to control important information such as the frame type, transmission direction, encryption, etc. The specific subfields include protocol version, frame type, subtype, To DS, and From DS.

[0068] Duration / ID: Used to set the duration or identifier of the frame, usually used in CTS and RTS frames.

[0069] Address field: includes receiving address, sending address, replacement address, etc., which are used to identify the sender and receiver of the frame.

[0070] Sequence Control: Control used to ensure the order and repetitive transmission of frames.

[0071] QoS Control: used to provide service quality assurance.

[0072] HT Control: Control for high throughput (HT) transmission.

[0073] Frame Body: Contains the actual data content.

[0074] FCS (Frame Check Sequence): used to ensure data integrity.

[0075] The frame structure of the 4G protocol mainly includes:

[0076] Radio frame: Each radio frame is 10 ms long and is divided into 10 sub-frames of equal size.

[0077] Subframe: Each subframe is 1ms long and consists of two equally sized slots. Each slot can be further divided into three subslots that may have different sizes, but in practical applications, each slot usually contains 7 or 6 OFDM symbols (depending on the type of cyclic prefix CP).

[0078] Slot: Each slot is 0.5ms long. In FDD, there are 10 subframes, 20 slots, or a maximum of 60 subslots available for downlink and uplink transmissions in every 10ms interval. Uplink and downlink transmissions are separated in the frequency domain.

[0079] After confirming the specific wireless protocol, the base station core board sends commands to the corresponding 4G, 5G, UWB or WiFi RF modules through Ethernet. The RF transmission power of these modules is generally set with different transmission levels, which are controlled by the module's own MCU for embedded software. For example, the level is divided from 1 to 10. When it is set to 10, the transmission power is the maximum, which is 30dBm. For each change in the transmission level, the transmission power changes by a certain dBm value. For example, if the transmission level of the power amplifier chip is reduced by one level, its transmission power is reduced by 0.5dBm. For example, when the MCU calculates that the received WiFi signal amplitude conversion success rate is 30dBm, the core board will send a command to the WiFi module, and the WiFi module will reduce the power transmission level to 5. The corresponding RF transmission power of 5 is about 25dBm. Generally, the transmission power is lower than 25dBm, and the radiation does not exceed the standard for human damage.

[0080] The antenna receives the signal u1 (transmitted signal), which is attenuated 10 times by the attenuator to u2. The signal amplified 5 times by the intermediate frequency is u4. The power of u4 remains unchanged when it passes through the intermediate frequency filter and detector to the MCU, so u1=(u4 / 5)*10. The unit of u1 is dBm. The conversion relationship between power (dBm) and watt (W) is u1=30+10lg(P / 1mW), P=1mW*10n, n=(u1+30) / 10. P(W) can be used to determine whether it is greater than 0.4W / m 2 。

[0081] UWB is a frequency modulated wave, 4G, 5G and wifi are amplitude modulated waves. Based on the modulation method, the received signals can be divided into two categories. The bandwidth of UWB modulation signal is 850kHz, the bandwidth of wifi modulation signal is 20MHz, the bandwidth of 4G modulation signal is 100~150MHz, and the bandwidth of 5G modulation signal is 400MHz. Based on the bandwidth analysis, the category of each modulation wave can be obtained.

[0082] The attenuator attenuates the signal amplitude to a range that can be received by the low-pass filter and can be received and processed by the next mixer.

[0083] Low-pass filtering filters out harmonics and clutter that are higher than the frequency band required for electromagnetic waves to be collected. For example, if you need to collect wifi (2.4GHz) and UWB (4.2GHz) signals, the filter will filter out all electromagnetic waves above 4.2GHz and retain the part below 4.2GHz.

[0084] Mixing is to add the collected signal (low-pass filter signal) and the local oscillator signal (reference signal) (it is a spectrum shifting process, which can be completed by a special multiplier chip, such as the AD633 series). Mixing is to reduce the frequency of the signal, that is, to obtain an intermediate frequency signal; the local oscillator signal can be generated by an oscillator, and the frequency can be fixed by itself, which is a reference signal. The mixed signal is generally weak, and the role of intermediate frequency amplification is to amplify this signal so that its amplitude can be received by the subsequent intermediate frequency filter. The intermediate frequency filter is used to filter out nonlinear spurious signals and ensure the linearity of the pre-amplifier circuit. Detection is to separate the information signal (the original information part of the modulated signal collected by the antenna) from the modulated signal, which is a demodulation process. Frequency analysis is the process of digitizing the low-frequency analog signal detected, then judging whether it is desirable, and giving the useful signal to the processing module such as MCU for processing.

[0085] The high-frequency modulated signal received by the antenna is first filtered to remove the useless part, then mixed to obtain an intermediate frequency signal (down-converted), and then the detector extracts the low-frequency analog signal with information (such as audio, data, etc.) from the intermediate frequency signal, and then digitizes this low-frequency analog signal. The digitized waveform can be truly processed and analyzed by the chip. For example, the electromagnetic wave signal of WiFi is a modulated signal carrying data, audio or video when it propagates in the air environment. This modulated signal is carried by a 2.4GHz carrier. Mixing is to neutralize this modulated signal into an intermediate frequency (tens of megahertz to hundreds of megahertz frequency), so that it can be detected by the detector. The detection process is the process of demodulating the data, audio and other data on the WiFi carrier. The demodulated waveform frequency is between tens of kHz and tens of kHz (the frequency band that can be digitally processed and analyzed by the MCU).

[0086] Furthermore, in the analysis step of this embodiment, the frequency range of 2.414 GHz to 4.2 GHz is locked, and frequency analysis is performed to obtain the signal frequency received by the antenna, and the signal protocol is obtained according to the signal frequency. The frequency range of the modulated wave is confirmed by locking the frequency band, and the analysis range can be narrowed for the subsequent analysis.

[0087] After frequency analysis, it can be concluded that the signal received by the antenna is 2.4GHz (wifi protocol), 3.9GHz (UWB protocol), 1.8GHz (4G protocol), 2.6GHz (5G protocol), etc., and then it can be known which protocol to control to reduce the transmission power. The command sent by the MCU is a string of binary data, such as "001", "010", "011", "100", etc., which correspond to "1", "2", "3", and "4" respectively when converted into decimal. After receiving the data, the base station controls the power amplifier chip to reduce the power of the corresponding value. 1 represents a reduction of 1 level (0.5dBm); 2 represents a reduction of 2 levels (actually a reduction of 1dBm), and so on.

[0088] Furthermore, in the fixed amplitude step of this embodiment, a 5W coaxial RF attenuator with a use range of 0-6GHz is used to fix the attenuation to 10dB.

[0089] Furthermore, in the low-pass filtering step of this embodiment, the low-pass filtering filters out the second harmonics of 2.4 GHz, 1.8 GHz and 2.7 GHz.

[0090] Furthermore, in the mixing step of this embodiment, the frequency generator generates a wave with a frequency of 20Mhz, a frequency stability of ±2.5ppm, and a phase noise level below -140dBc / Hz; during mixing, the mixer multiplies two electrical signals of different frequencies to generate a new frequency signal, the noise coefficient of the mixer is less than 15dB, the frequency conversion loss is between 5dB and 8dB, and the isolation is above 30dB.

[0091] Furthermore, in the intermediate frequency filtering step of this embodiment, the filtered signal is an intermediate frequency signal of 2.4 GHz to 4.2 GHz selected by the passband, and waves outside the range of 2.4 GHz to 4.2 GHz are filtered out.

[0092] The processing module of the present invention, such as MCU, sends a command to the base station core board, in which the information includes the strength of the signal transmitted by the antenna. The command includes the RSSI (RSSI: Received Signal Strength Indicator) value of the signal. The base station core board changes the transmission power of the wireless protocol according to whether the RSSI value of the antenna is too large, so as to ensure the reliability of the device radiation.

[0093] A system for limiting the radiation of radio electromagnetic waves to the human body in underground mines, comprising:

[0094] Fixed amplitude module: The antenna receives radio electromagnetic waves and fixes the attenuation signal amplitude;

[0095] Low-pass filtering module: low-pass filtering is performed through a low-pass filter;

[0096] Mixing module: The wave generated by the frequency generator is multiplied by the phase-locked loop and mixed with the signal after low-pass filtering to produce a new frequency signal;

[0097] Intermediate frequency filtering module: amplifies the new frequency signal through the intermediate frequency, and filters out the intermediate frequency signal through the intermediate frequency filter;

[0098] Detection module: obtain the envelope of the original information signal through the envelope detector to obtain the modulation mode, frequency and bandwidth;

[0099] Analysis module: Calculates the radiation intensity of radio electromagnetic waves. If the radiation intensity of radio electromagnetic waves is greater than the set value, locks the frequency band and performs analysis. First, the media access control layer analyzes the MAC characteristics in the media control layer, analyzes the channel access mechanism, captures the frame structure, locates the wireless protocol according to the frame structure, and sends commands to the base station core board according to the wireless protocol and power of the radio electromagnetic waves.

[0100] Change power module: The base station core board changes the transmission power of the corresponding wireless protocol according to the command.

[0101] Further, preferably, in the analysis module of this embodiment, the throughput and delay time of the transmission data are collected through carrier sense multiple access to determine whether the access mechanism is a random access mechanism or a controlled access mechanism.

[0102] Furthermore, in the analysis module of this embodiment, data is first collected for a fixed period of 8-15 minutes, and the statistical throughput is between 1kbps and 1000kbps, and the size of each data packet is consistent, and the interval delay time from the first data packet to the second data packet of the same type is between 10ms and 1000ms, which belongs to the controlled access mechanism; the throughput is between 1kbps and 1000Mbps and the size of each data packet is inconsistent, and the interval delay time from the first data packet to the second data packet of the same type is irregular, which belongs to the random access mechanism.

[0103] Further, preferably, in the analysis module of this embodiment, data is first collected for a fixed period of 10 minutes, and the statistical throughput is between 1kbps and 1000kbps, and the size of each data packet is consistent, and the interval delay time from the first data packet to the second data packet of the same type is between 10ms and 1000ms, which belongs to the controlled access mechanism; the throughput is between 1kbps and 1000Mbps, the size of each data packet is inconsistent, and the interval delay time from the first data packet to the second data packet of the same type is irregular, which belongs to the random access mechanism.

[0104] The present invention can also analyze the access mechanism of the channel through access mechanisms such as conflict avoidance and time slot polling.

[0105] Furthermore, in the analysis module of this embodiment, according to the characteristics of the frame structure, the header, namely the frame header, the data part, and the tail, namely the frame tail, are analyzed to locate the wireless protocol.

[0106] Further, preferably, in the analysis module of this embodiment, the positioning wireless protocol includes:

[0107] Identify the frame type: Determine the frame type by looking at the protocol type field in the frame header; such as Ethernet frame, IP datagram, TCP segment, or UDP datagram.

[0108] Check the frame header fields: Analyze the various fields in the frame header, including one or more of the source address, destination address, frame length, and protocol type; these fields provide important information about the source and destination of the frame, the size of the frame, and the protocol used.

[0109] Analyze the data part: determine the content, format, and size of the data based on the frame header information; for some protocols, such as TCP and UDP, the data part may also contain additional metadata, such as port number, sequence number, acknowledgment number, and window size.

[0110] Verify the frame trailer checksum: Use the checksum in the frame trailer to verify the integrity of the data. If errors are found, you may need to request a retransmission or take other corrective action.

[0111] Specifically analyze the characteristics of the wireless protocol such as the preamble, frame start delimiter (SFD), destination MAC address, source MAC address, type / length field, data part and frame check sequence (FCS).

[0112] For example, the frame structure of UWB includes: Preamble (SYNC): a three-element symbol table (such as {1,-1,0}), synchronization code / frame start delimiter (SFD): prompts the receiver that the previous SYNC preamble synchronization has ended, physical layer header (PHR): contains additional information about the frame, data field (PSDU / data): used to transmit actual user data, check code: used to detect errors in received data and correct errors. Another example is the 5G frame structure: Frame length: The 5G NR frame structure consists of 10 milliseconds (ms) frames. Subframe division: Each frame is further divided into 10 subframes, each of which is 1 millisecond (ms) long. The characteristics of the above wireless protocols can be used to locate the scope of specific wireless protocols.

[0113] Such as a. Preamble and SFD, used for synchronization and identification of the start of the frame; b. Destination MAC address and source MAC address, indicating the receiver and sender of the frame respectively; c. Type / length field: indicates whether the content of the data part is an IP datagram or other types of data, or the length of the data part; d. Data part: contains the actual data content of the transmission. e. FCS: used for error detection and correction.

[0114] The frame format of the WIFI protocol mainly includes:

[0115] Frame Control: This is the beginning of the MAC frame, with a length of 2 bytes. It contains multiple subfields, which are used to control important information such as the frame type, transmission direction, encryption, etc. The specific subfields include protocol version, frame type, subtype, To DS, and From DS.

[0116] Duration / ID: Used to set the duration or identifier of the frame, usually used in CTS and RTS frames.

[0117] Address field: includes receiving address, sending address, replacement address, etc., which are used to identify the sender and receiver of the frame.

[0118] Sequence Control: Control used to ensure the order and repetitive transmission of frames.

[0119] QoS Control: used to provide service quality assurance.

[0120] HT Control: Control for high throughput (HT) transmission.

[0121] Frame Body: Contains the actual data content.

[0122] FCS (Frame Check Sequence): used to ensure data integrity.

[0123] The frame format of the 4G protocol mainly includes:

[0124] Radio frame: Each radio frame is 10 ms long and is divided into 10 sub-frames of equal size.

[0125] Subframe: Each subframe is 1ms long and consists of two equally sized slots. Each slot can be further divided into three subslots that may have different sizes, but in practical applications, each slot usually contains 7 or 6 OFDM symbols (depending on the type of cyclic prefix CP).

[0126] Slot: Each slot is 0.5ms long. In FDD, there are 10 subframes, 20 slots, or a maximum of 60 subslots available for downlink and uplink transmissions in every 10ms interval. Uplink and downlink transmissions are separated in the frequency domain.

[0127] After confirming the specific wireless protocol, the base station core board sends commands to the corresponding 4G, 5G, UWB or WiFi RF modules through Ethernet. The RF transmission power of these modules is generally set with different transmission levels, which are controlled by the module's own MCU for embedded software. For example, the level is divided from 1 to 10. When it is set to 10, the transmission power is the maximum, which is 30dBm. For each change in the transmission level, the transmission power changes by a certain dBm value. For example, if the transmission level of the power amplifier chip is reduced by one level, its transmission power is reduced by 0.5dBm. For example, when the MCU calculates that the received WiFi signal amplitude conversion success rate is 30dBm, the core board will send a command to the WiFi module, and the WiFi module will reduce the power transmission level to 5. The corresponding RF transmission power of 5 is about 25dBm. Generally, the transmission power is lower than 25dBm, and the radiation does not exceed the standard for human damage.

[0128] The antenna receives the signal u1 (transmitted signal), which is attenuated 10 times by the attenuator to u2. The signal amplified 5 times by the intermediate frequency is u4. The power of u4 remains unchanged when it passes through the intermediate frequency filter and detector to the MCU, so u1=(u4 / 5)*10. The unit of u1 is dBm. The conversion relationship between power (dBm) and watt (W) is u1=30+10lg(P / 1mW), P=1mW*10n, n=(u1+30) / 10. P(W) can be used to determine whether it is greater than 0.4W / m 2 。

[0129] UWB is a frequency modulated wave, 4G, 5G and wifi are amplitude modulated waves. Based on the modulation method, the received signals can be divided into two categories. The bandwidth of UWB modulation signal is 850kHz, the bandwidth of wifi modulation signal is 20MHz, the bandwidth of 4G modulation signal is 100~150MHz, and the bandwidth of 5G modulation signal is 400MHz. Based on the bandwidth analysis, the category of each modulation wave can be obtained.

[0130] The attenuator attenuates the signal amplitude to a range that can be received by the low-pass filter and can be received and processed by the next mixer.

[0131] Low-pass filtering filters out harmonics and clutter that are higher than the frequency band required for electromagnetic waves to be collected. For example, if you need to collect wifi (2.4GHz) and UWB (4.2GHz) signals, the filter will filter out all electromagnetic waves above 4.2GHz and retain the part below 4.2GHz.

[0132] Mixing is to add the collected signal (low-pass filter signal) and the local oscillator signal (reference signal) (it is a spectrum shifting process, which can be completed by a special multiplier chip, such as the AD633 series). Mixing is to reduce the frequency of the signal, that is, to obtain an intermediate frequency signal; the local oscillator signal can be generated by an oscillator, and the frequency can be fixed by itself, which is a reference signal. The mixed signal is generally weak, and the role of intermediate frequency amplification is to amplify this signal so that its amplitude can be received by the subsequent intermediate frequency filter. The intermediate frequency filter is used to filter out nonlinear spurious signals and ensure the linearity of the pre-amplifier circuit. Detection is to separate the information signal (the original information part of the modulated signal collected by the antenna) from the modulated signal, which is a demodulation process. Frequency analysis is the process of digitizing the low-frequency analog signal detected, then judging whether it is desirable, and giving the useful signal to the processing module such as MCU for processing.

[0133] The high-frequency modulated signal received by the antenna is first filtered to remove the useless part, then mixed to obtain an intermediate frequency signal (down-converted), and then the detector extracts the low-frequency analog signal with information (such as audio, data, etc.) from the intermediate frequency signal, and then digitizes this low-frequency analog signal. The digitized waveform can be truly processed and analyzed by the chip. For example, the electromagnetic wave signal of WiFi is a modulated signal carrying data, audio or video when it propagates in the air environment. This modulated signal is carried by a 2.4GHz carrier. Mixing is to neutralize this modulated signal into an intermediate frequency (tens of megahertz to hundreds of megahertz frequency), so that it can be detected by the detector. The detection process is the process of demodulating the data, audio and other data on the WiFi carrier. The demodulated waveform frequency is between tens of kHz and tens of kHz (the frequency band that can be digitally processed and analyzed by the MCU).

[0134] Furthermore, in the analysis step of this embodiment, the frequency range of 2.414 GHz to 4.2 GHz is locked, and frequency analysis is performed to obtain the signal frequency received by the antenna, and the signal protocol is obtained according to the signal frequency. The frequency range of the modulated wave is confirmed by locking the frequency band, and the analysis range can be narrowed for the subsequent analysis.

[0135] After frequency analysis, it can be concluded that the signal received by the antenna is 2.4GHz (wifi protocol), 3.9GHz (UWB protocol), 1.8GHz (4G protocol), 2.6GHz (5G protocol), etc., and then it can be known which protocol to control to reduce the transmission power. The command sent by the MCU is a string of binary data, such as "001", "010", "011", "100", etc., which correspond to "1", "2", "3", and "4" respectively when converted into decimal. After receiving the data, the base station controls the power amplifier chip to reduce the power of the corresponding value. 1 represents a reduction of 1 level (0.5dBm); 2 represents a reduction of 2 levels (actually a reduction of 1dBm), and so on.

[0136] Furthermore, in the fixed amplitude module of this embodiment, a 5W coaxial RF attenuator with a use range of 0-6GHz is used to fix the attenuation to 10dB.

[0137] Furthermore, in the low-pass filter module of this embodiment, the low-pass filter filters out the second harmonics of 2.4 GHz, 1.8 GHz and 2.7 GHz.

[0138] Furthermore, in the mixing module of this embodiment, the frequency generator generates a wave with a frequency of 20Mhz, a frequency stability of ±2.5ppm, and a phase noise level below -140dBc / Hz; during mixing, the mixer multiplies two electrical signals of different frequencies to generate a new frequency signal, the noise coefficient of the mixer is less than 15dB, the frequency conversion loss is between 5dB and 8dB, and the isolation is above 30dB.

[0139] Furthermore, in the intermediate frequency filtering module of this embodiment, the filtered signal is an intermediate frequency signal of 2.4 GHz to 4.2 GHz selected by the passband, and waves outside the range of 2.4 GHz to 4.2 GHz are filtered out.

[0140] The method and system of limiting the radiation of radio electromagnetic waves to the human body in underground mines of the present invention is a kind of intelligent monitoring, which does not require manual operation and has high feasibility. It can be carried by miners or vehicles. Once entering the range where the radio wave radiation exceeds the standard, it can make an independent judgment and then notify the base station where the radiation exceeds the standard to weaken the corresponding radio waves, thereby reducing the radiation damage to the human body and ensuring personal health and safety. The invention enhances the safety of mine operations, improves convenience, and complies with the theme of safe production in mines. The present invention provides more powerful support for safe production in mines and the health of miners in a more intelligent, energy-saving and efficient manner.

[0141] Based on the above ideal embodiments of this application, the relevant staff can make various changes and modifications without departing from the technical concept of this application through the above description. The technical scope of this application is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

[0142] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0143] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0144] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0145] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

Claims

1. A method for limiting the radiation of radio electromagnetic waves to the human body in underground mines, characterized in that: include: Fixed amplitude: Receive radio electromagnetic waves and fix the attenuation signal amplitude; Low-pass filtering: Low-pass filtering is performed through a low-pass filter; Mixing: The wave generated by the frequency generator is multiplied by the phase-locked loop and mixed with the signal after low-pass filtering to produce a new frequency signal; Intermediate frequency filtering: amplify the new frequency signal through the intermediate frequency, and filter out the intermediate frequency signal through the intermediate frequency filter; Detection: The envelope of the original information signal is obtained through the detector to obtain the modulation mode, frequency, and bandwidth; Analysis: Calculate the radiation intensity of the radio electromagnetic wave. If the radiation intensity of the radio electromagnetic wave is greater than the set value, lock the frequency band and conduct analysis. First, analyze the media access control layer through the MAC characteristics in the media control layer, analyze the channel access mechanism, capture the frame structure, locate the wireless protocol according to the frame structure, and send commands to the base station core board according to the wireless protocol and power of the radio electromagnetic wave; Change power: The base station core board changes the transmission power of the corresponding wireless protocol according to the command.

2. The method for limiting the radiation of radio electromagnetic waves to the human body in underground mines according to claim 1 is characterized in that: In the analysis step, the throughput and delay time of the transmission data are collected through carrier sense multiple access, and it is determined whether the access mechanism is a random access mechanism or a controlled access mechanism.

3. The method for limiting the radiation of radio electromagnetic waves to the human body in underground mines according to claim 1 is characterized in that: In the analysis step, data is first collected for a fixed period of 8-15 minutes. If the throughput is between 1kbps and 1000kbps, and the size of each data packet is consistent, and the interval delay time from the first data packet to the second data packet of the same type is between 10ms and 1000ms, it belongs to a controlled access mechanism; if the throughput is between 1kbps and 1000Mbps and the size of each data packet is inconsistent, and the interval delay time from the first data packet to the second data packet of the same type is irregular, it belongs to a random access mechanism.

4. The method for limiting the radiation of radio electromagnetic waves to the human body in underground mines according to claim 1 is characterized in that: In the analysis, the header, data part and tail are analyzed to locate the wireless protocol according to the characteristics of the frame structure.

5. The method for limiting the radiation of radio electromagnetic waves to the human body in underground mines according to claim 1 is characterized in that: During the analysis, locating the wireless protocol includes: Identify frame type: Determine the frame type by looking at the protocol type field in the frame header; Check the frame header fields: Analyze each field in the frame header, including one or more of the source address, destination address, frame length, and protocol type. Data analysis part: determine the content, format and size of the data based on the frame header information; Verify frame trailer checksum: Use the checksum in the frame trailer to verify data integrity.

6. The method for limiting the radiation of radio electromagnetic waves to the human body in underground mines according to any one of claims 1 to 5, characterized in that: In the fixed amplitude step, a 5W coaxial RF attenuator with a use range of 0-6GHz is used to fix the attenuation to 10dB. In the low-pass filtering step, the low-pass filter filters out the second harmonics of 2.4GHz, 1.8GHz and 2.7GHz.

7. The method for limiting the radiation of radio electromagnetic waves to the human body in underground mines according to any one of claims 1 to 5, characterized in that: In the mixing step, the frequency generator generates a wave with a frequency of 20Mhz, a frequency stability of ±2.5ppm, and a phase noise level below -140dBc / Hz; during mixing, the mixer multiplies two electrical signals of different frequencies to generate a new frequency signal, the noise coefficient of the mixer is less than 15dB, the frequency conversion loss is between 5dB and 8dB, and the isolation is above 30dB.

8. The method for limiting the radiation of radio electromagnetic waves to the human body in underground mines according to any one of claims 1 to 5, characterized in that: In the intermediate frequency filtering step, the filtered signal is an intermediate frequency signal of 2.4 GHz to 4.2 GHz selected by the passband, and waves outside the range of 2.4 GHz to 4.2 GHz are filtered out.

9. The method for limiting the radiation of radio electromagnetic waves to the human body in underground mines according to any one of claims 1 to 5, characterized in that: In the analysis step, the frequency band range of 2.414 GHz to 4.2 GHz is locked, and frequency analysis is performed to obtain the signal frequency received by the antenna, and the signal protocol is obtained according to the signal frequency.

10. A system for limiting the radiation of radio electromagnetic waves to the human body in underground mines, characterized in that: include: Fixed amplitude module: receives radio electromagnetic waves and fixes the attenuation signal amplitude; Low-pass filtering module: low-pass filtering is performed through a low-pass filter; Mixing module: The wave generated by the frequency generator is multiplied by the phase-locked loop and mixed with the signal after low-pass filtering to produce a new frequency signal; Intermediate frequency filtering module: amplifies the new frequency signal through the intermediate frequency, and filters out the intermediate frequency signal through the intermediate frequency filter; Detection module: obtains the envelope of the original information signal through the detector to obtain the modulation mode, frequency and bandwidth; Analysis module: Calculates the radiation intensity of radio electromagnetic waves. If the radiation intensity of radio electromagnetic waves is greater than the set value, locks the frequency band and performs analysis. First, the media access control layer analyzes the MAC characteristics in the media control layer, analyzes the channel access mechanism, captures the frame structure, locates the wireless protocol according to the frame structure, and sends commands to the base station core board according to the wireless protocol and power of the radio electromagnetic waves. Change power module: The base station core board changes the transmission power of the corresponding wireless protocol according to the command.

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