An electromagnetic safety data acquisition system downhole

Abstract

This invention belongs to the field of signal acquisition and analysis technology, specifically relating to a downhole electromagnetic safety data acquisition system, including an electromagnetic signal time-frequency acquisition module, an isolated network security transmission module, and a power supply module. The power supply module's output terminal is electrically connected to the power supply input terminals of both the electromagnetic signal time-frequency acquisition module and the isolated network security transmission module, providing stable power to both modules. The signal output terminal of the electromagnetic signal time-frequency acquisition module is communicatively connected to the signal input terminal of the isolated network security transmission module. The signal output terminal of the isolated network security transmission module is communicatively connected to a ground monitoring center. This system can acquire electromagnetic signals across the entire frequency band from 9kHz to 20GHz. The RF front-end uses two heterodyne receiving channels sharing a common intermediate frequency down-conversion circuit, and the high-speed baseband uses a single ADC multiplexing design, significantly reducing circuit size and hardware overhead.

Description

Technical Field

[0001] This invention belongs to the field of signal acquisition and analysis technology, specifically relating to a downhole electromagnetic safety data acquisition system. Background Technology

[0002] Coal mines are high-risk, enclosed, and electromagnetically complex operating environments. Underground wireless communication, monitoring, electromechanical control, and explosion-proof electrical equipment operate intensively, creating a complex electromagnetic space with multiple types, frequency bands, and links of electromagnetic signals. Disorderly electromagnetic interference and illegal electromagnetic signal intrusion can easily cause equipment communication interruptions, distorted monitoring data, and erroneous triggering of control commands, seriously threatening safe production underground. Therefore, it is urgent to conduct real-time acquisition, feature identification, and safety management of electromagnetic signals throughout the underground environment, and to construct a safe monitoring system for the underground electromagnetic space.

[0003] Current conventional electromagnetic signal acquisition and transmission equipment cannot meet the special application needs of underground coal mines and has many technical shortcomings: 1. Insufficient electromagnetic signal acquisition capability: Existing acquisition equipment has a limited frequency band coverage, making it difficult to achieve continuous acquisition and processing across a wide frequency band of 9kHz to 20GHz; the RF front-end mostly adopts a discrete channel independent design, failing to achieve shared intermediate frequency circuitry for the heterodyne receiver channel, and the high-speed baseband does not use an ADC multiplexing architecture, resulting in low equipment integration, large size, and inability to adapt to installation in confined underground spaces; at the same time, it lacks the ability to accurately acquire electromagnetic transient signals, maintain stable storage over long periods, and calibrate data time stamps, making it difficult to uncover the characteristic patterns of electromagnetic signals underground.

[0004] 2. Poor security and isolation of underground data transmission: Existing transmission equipment does not adopt intrinsically safe opto-isolation and visible light isolation transmission technologies, which cannot achieve complete electrical isolation between the acquisition module (intrinsically safe side) and the underground industrial ring network (non-safe side), making it prone to fault potential crosstalk; it does not support multi-protocol compatibility and high-strength encryption verification, making data easy to be tampered with and stolen during transmission, and it cannot eliminate electromagnetic noise in the optical transmission process. The security, reliability and real-time performance of data transmission cannot meet the requirements of coal mine industrial ring network transmission.

[0005] 3. Lack of stability and intrinsic safety performance of underground power supply: The underground power grid is subject to strong interference and harsh environment. The existing power supply modules have not passed the comprehensive EMI filtering and electromagnetic compatibility design and do not meet the GB / T 17626 electromagnetic compatibility standard. They lack high-frequency electrical isolation, precision voltage regulation and ultra-low noise output capabilities, and cannot provide clean power supply for precision acquisition circuits. At the same time, they are not equipped with a fast-response intrinsic safety protection mechanism, resulting in poor power supply safety and environmental adaptability, which can easily lead to equipment failure.

[0006] 4. Limited signal processing and measurement functions: Existing equipment does not adopt a highly integrated SOC signal processing architecture, has poor digital signal processing scalability, and cannot realize core functions such as digital orthogonal downconversion, spectrum analysis, and field strength analysis; it only supports a single measurement mode and lacks diversified measurement capabilities such as panoramic scanning, frequency scanning, storage scanning, and fixed frequency measurement, making it difficult to meet the electromagnetic signal monitoring needs of multiple scenarios in underground mines.

[0007] In summary, existing electromagnetic data acquisition systems cannot meet the requirements of underground applications such as wide-band acquisition, miniaturized integration, intrinsically safe transmission, stable power supply, and multi-mode measurement. They are also insufficient to support electromagnetic safety feature identification, sample library construction, and safety management in coal mines. Therefore, there is an urgent need to develop an electromagnetic safety data acquisition system that is adapted to the special environment of underground coal mines. Summary of the Invention

[0008] To address the technical problems existing in the aforementioned electromagnetic data acquisition systems, this invention provides a downhole electromagnetic safety data acquisition system.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A downhole electromagnetic safety data acquisition system includes an electromagnetic signal time-frequency acquisition module, an isolated network security transmission module, and a power supply module; The power output terminal of the power module is electrically connected to the power input terminal of the electromagnetic signal time and frequency acquisition module and the power input terminal of the isolated network security transmission module, respectively, to provide stable power to the two modules; The signal output terminal of the electromagnetic signal time-frequency acquisition module is communicatively connected to the signal input terminal of the isolated network security transmission module; The signal output terminal of the isolated network security transmission module is connected to the ground monitoring center for communication. The electromagnetic signal time-frequency acquisition module is composed of a radio frequency front-end and a high-speed baseband connected in sequence, and is used to acquire and process electromagnetic signals in the frequency range of 9kHz to 20GHz. The isolated network security transmission module is used to realize cross-domain physically isolated visible light transmission of data between different electromagnetic environments, different networks and physical isolation systems, remove optical transmission noise and transmit the processed data securely, reliably and in real time to the ground monitoring center; The power module is used to provide stable, clean, and intrinsically safe electrical energy for all downhole equipment.

[0010] The radio frequency front end is provided with a low-loss pre-programmable attenuator, a low-pass filter with a cutoff frequency of 20 GHz, and a signal distribution switch in sequence along the signal input direction. The three output terminals of the signal distribution switch are respectively connected to the signal input terminals of the direct sampling channel and the two heterodyne receiving channels; The direct sampling channel is used to process signals in the 9kHz to 30MHz frequency band, and the two heterodyne receiving channels are used to process signals in the 20MHz to 3.5GHz frequency band and the 3.5GHz to 20GHz frequency band, respectively. The two heterodyne receiving channels share the same intermediate frequency downconversion circuit, and the signal output terminals of the direct sampling channel and the two heterodyne receiving channels are all connected to the high-speed ADC signal input terminal of the high-speed baseband.

[0011] The direct sampling channel is provided with a 7th-order lumped LC low-pass filter, a bypassable low-noise amplifier, and a programmable amplifier in sequence along the signal flow direction. The signal output terminal of the direct sampling channel is connected to the high-speed ADC signal input terminal of the high-speed baseband via an RF front-end output distribution switch.

[0012] The high-speed baseband adopts an ADC+FPGA+ARM / DSP+integrated architecture, with the FPGA and ARM / DSP integrated inside a single SOC die, sharing memory and power system. The signal output terminal of the ADC is connected to the signal input terminal of the FPGA on the SOC die, and the signal output terminal of the SOC die is connected to the intrinsically safe signal input terminal of the isolated network security transmission module.

[0013] The system's supporting software is divided into an RF receiving and control unit, a high-speed data signal processing unit, a measurement and testing unit, and a terminal unit. The control signal output terminal of the RF receiver control unit is connected to the control signal input terminal of the RF front end, and the signal input terminal of the high-speed data signal processing unit is connected to the FPGA signal output terminal of the high-speed baseband. The high-speed data signal processing unit, the measurement and testing unit, and the terminal unit are connected in sequence for communication.

[0014] The high-speed data signal processing unit is integrated inside the FPGA of the SOC die, and sequentially performs digital quadrature downconversion, multiple decimation, digital filtering, windowing, spectrum analysis, and level measurement operations along the signal processing direction.

[0015] The isolated network security transmission module adopts a dual-core isolation architecture, which is divided into an intrinsically secure side and a non-secure side. The signal input terminal on the intrinsically safe side is connected to the signal output terminal of the electromagnetic signal time and frequency acquisition module, while the signal output terminal on the non-safe side is connected to the ground monitoring center through the underground industrial ring network. Complete electrical isolation between the intrinsically safe side and the non-safe side is achieved through a high-speed digital isolation chip and a DC-DC isolation power supply module, with an isolation withstand voltage ≥2500Vrms; The isolated network security transmission module supports TCP / IP, UDP, and Modbus TCP protocols, and supports AES-128 or AES-256 encrypted transmission, as well as CRC32 or MD5 checksums.

[0016] The intrinsically safe side uses a low-power ARM Cortex-M series MCU, while the non-safe side uses an industrial-grade network processor; all power and signal interfaces on the intrinsically safe side are equipped with intrinsically safe certified isolation barriers or protection circuits.

[0017] The power module is arranged sequentially along the power flow direction as follows: a front-stage EMI filter rectifier circuit, a full-bridge topology PWM controlled high-frequency isolation transformer, a rear-stage synchronous rectification and precision voltage regulation circuit, and a linear voltage regulator. The power supply output terminal of the linear regulator is electrically connected to the power supply input terminal of the electromagnetic signal time-frequency acquisition module and the isolated network security transmission module, respectively.

[0018] The power module is equipped with a dual intrinsically safe protection circuit combining current limiting, voltage limiting, and fuses, with a protection response time of <10μs, meeting the GB / T 17626 electromagnetic compatibility standard.

[0019] Compared with the prior art, the beneficial effects of this invention are: 1. The system of this invention can complete the acquisition of electromagnetic signals in the full frequency band from 9kHz to 20GHz. The radio frequency front-end adopts two heterodyne receiving channels sharing the intermediate frequency downconversion circuit, and the high-speed baseband adopts a single ADC multiplexing design, which greatly reduces the circuit size and hardware overhead. With the SOC integrated architecture, while improving the hardware integration, it supports four measurement modes such as panoramic scanning and frequency scanning, which is perfectly adapted to the narrow and complex installation environment in coal mines and meets the needs of long-term, multi-state electromagnetic signal acquisition and feature extraction.

[0020] 2. This invention achieves complete electrical isolation between the intrinsically safe and non-safe sides through intrinsically safe opto-isolation technology, eliminating fault potential crosstalk, and eliminating optical transmission noise in conjunction with visible light isolation transmission technology; at the same time, it supports compatibility with multiple industrial protocols and high-strength encryption and verification mechanisms, enabling the safe, real-time, and tamper-free transmission of collected data to the ground monitoring center in the coal mine industrial ring network, comprehensively improving the safety and stability of underground electromagnetic data transmission.

[0021] 3. The power module of this invention is designed with EMI filtering, high-frequency electrical isolation and precision voltage regulation to meet electromagnetic compatibility standards and provide ultra-low noise and clean power supply. With fast intrinsic safety protection circuit, it can provide stable power supply in harsh downhole environments. The high-speed baseband adopts an integrated digital signal processing link, which can quickly complete time domain or frequency domain conversion, spectrum analysis, field strength analysis and other processing, which greatly improves the efficiency of electromagnetic signal analysis and the robustness of system operation. Attached Figure Description

[0022] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0023] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0024] Figure 1 This is a signal flow diagram of the overall functional modules of the present invention; Figure 2 This is a structural diagram of the radio frequency input stage and direct sampling channel of the present invention; Figure 3 This is a high-speed baseband scheme diagram of the present invention; Figure 4 This is a flowchart illustrating the spectrum analysis implementation of the present invention; Figure 5 This is a radio frequency front-end control diagram of the present invention; Figure 6 This is a high-speed digital signal processing link diagram of the FPGA of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. These descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the claims of the present invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] like Figure 1 As shown, the RF received signal enters the preamplifier attenuation module, where it is attenuated by an adjustable RF attenuator and amplified by an LNA (optional) to adjust the signal to a suitable level and ensure optimal noise figure for the receiving channel. The RF received signal then enters the preselector to suppress out-of-band unknown interference signals to ensure sufficient dynamic range, and then enters the corresponding frequency band downconversion module to be converted to a digitally processable intermediate frequency (IF) signal. Finally, it is sent to the digitizer for ADC sampling and digital signal processing. The clock module provides a 100MHz reference signal to the frequency synthesis module and the digitizer module, while the frequency synthesis module provides the required local oscillator signal to the downconversion module.

[0029] like Figure 2 As shown, the RF received signal first passes through a low-loss pre-programmable attenuator for amplitude pre-adjustment. This design effectively improves the dynamic range of the receiver during linear operation. Simultaneously, because the attenuator is placed before the main input channel, the dynamic range adjustment requirements for each segment receiver are effectively reduced. The layout size is also reduced by using a multiplexed programmable attenuator. Following the attenuator is a low-pass filter with a cutoff frequency of 20GHz for overall frequency band pre-selection. Then, a switch distributes the signal to three paths: 9kHz–30MHz, 20MHz–3.5GHz, and 3.5GHz–20GHz, for individual processing.

[0030] like Figure 3 As shown, the high-speed baseband adopts the mainstream instrument architecture of ADC+FPGA+ARM / DSP+general-purpose computer.

[0031] like Figure 4 As shown, the spectrum analysis path completes spectrum analysis and frequency measurement. After sampling, the digital signal passes through a digital downconverter, digital filter bank, FFT operation, and preprocessing (normal, average, minimum hold, or maximum hold). The spectrum data and frequency measurement results are then output to the terminal industrial control computer or computer for display. The bandwidth of the bandpass filter bank is 10kHz to 10MHz. The spectral resolution bandwidth is obtained by dividing the baseband data sampling rate after DDC by the number of FFT points. After downconversion, the signal becomes zero intermediate frequency (IF). Low-pass filters filter the I / Q data respectively. The filters include CIC, HB, and FIR. When the bandwidth is narrow, the data stream must be decimated and slowed down after zero IF processing.

[0032] like Figure 5 As shown, the main contents of RF front-end control include: 1) Switch control, including filter banks. 2) Control of programmable attenuators and programmable amplifiers. 3) Control of multiple local oscillator circuits. 4) Synchronization timing processing of the above control contents with baseband control at high-speed frequency hopping (2500 hops / s).

[0033] like Figure 6 As shown, high-speed digital signal processing is mainly implemented by the FPGA portion of the SOC, providing high design flexibility and scalability. SOC-FPGA digital signal processing includes digital quadrature downconversion, decimation, digital filtering, windowing, spectrum analysis, and level measurement.

[0034] This system has the following four modes: panoramic scan, frequency scan, storage scan, and fixed frequency measurement mode.

[0035] The above description only illustrates the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention, and all such changes should be included within the protection scope of the present invention.

Claims

1. An electromagnetic safety data acquisition system downhole, characterized by: It includes an electromagnetic signal time and frequency acquisition module, an isolated network security transmission module, and a power supply module; The power output terminal of the power module is electrically connected to the power input terminal of the electromagnetic signal time and frequency acquisition module and the power input terminal of the isolated network security transmission module, respectively, to provide stable power to the two modules; The signal output terminal of the electromagnetic signal time-frequency acquisition module is communicatively connected to the signal input terminal of the isolated network security transmission module; The signal output terminal of the isolated network security transmission module is connected to the ground monitoring center for communication. The electromagnetic signal time-frequency acquisition module is composed of a radio frequency front-end and a high-speed baseband connected in sequence, and is used to acquire and process electromagnetic signals in the frequency range of 9kHz to 20GHz. The isolated network security transmission module is used to realize cross-domain physically isolated visible light transmission of data between different electromagnetic environments, different networks and physical isolation systems, remove optical transmission noise and transmit the processed data securely, reliably and in real time to the ground monitoring center; The power module is used to provide stable, clean, and intrinsically safe electrical energy for all downhole equipment.

2. An electromagnetic safety data acquisition system downhole according to claim 1, characterized in that: The radio frequency front end is provided with a low-loss pre-programmable attenuator, a low-pass filter with a cutoff frequency of 20 GHz, and a signal distribution switch in sequence along the signal input direction. The three output terminals of the signal distribution switch are respectively connected to the signal input terminals of the direct sampling channel and the two heterodyne receiving channels; The direct sampling channel is used to process signals in the 9kHz to 30MHz frequency band, and the two heterodyne receiving channels are used to process signals in the 20MHz to 3.5GHz frequency band and the 3.5GHz to 20GHz frequency band, respectively. The two heterodyne receiving channels share the same intermediate frequency downconversion circuit, and the signal output terminals of the direct sampling channel and the two heterodyne receiving channels are all connected to the high-speed ADC signal input terminal of the high-speed baseband.

3. An electromagnetic safety data acquisition system downhole according to claim 2, characterized in that: The direct sampling channel is provided with a 7th-order lumped LC low-pass filter, a bypassable low-noise amplifier, and a programmable amplifier in sequence along the signal flow direction. The signal output terminal of the direct sampling channel is connected to the high-speed ADC signal input terminal of the high-speed baseband via an RF front-end output distribution switch.

4. An electromagnetic safety data acquisition system downhole according to claim 2, characterized in that: The high-speed baseband adopts an ADC+FPGA+ARM / DSP+integrated architecture, with the FPGA and ARM / DSP integrated inside a single SOC die, sharing memory and power system. The signal output terminal of the ADC is connected to the signal input terminal of the FPGA on the SOC die, and the signal output terminal of the SOC die is connected to the intrinsically safe signal input terminal of the isolated network security transmission module.

5. A downhole electromagnetic safety data acquisition system as defined in claim 1, wherein: The system's supporting software is divided into an RF receiving and control unit, a high-speed data signal processing unit, a measurement and testing unit, and a terminal unit. The control signal output terminal of the RF receiver control unit is connected to the control signal input terminal of the RF front end, and the signal input terminal of the high-speed data signal processing unit is connected to the FPGA signal output terminal of the high-speed baseband. The high-speed data signal processing unit, the measurement and testing unit, and the terminal unit are connected in sequence for communication.

6. The downhole electromagnetic safety data acquisition system according to claim 5, characterized in that: The high-speed data signal processing unit is integrated inside the FPGA of the SOC die, and sequentially performs digital quadrature downconversion, multiple decimation, digital filtering, windowing, spectrum analysis, and level measurement operations along the signal processing direction.

7. A downhole electromagnetic safety data acquisition system as defined in claim 1, wherein: The isolated network security transmission module adopts a dual-core isolation architecture, which is divided into an intrinsically secure side and a non-secure side. The signal input terminal on the intrinsically safe side is connected to the signal output terminal of the electromagnetic signal time and frequency acquisition module, while the signal output terminal on the non-safe side is connected to the ground monitoring center through the underground industrial ring network. Complete electrical isolation between the intrinsically safe side and the non-safe side is achieved through a high-speed digital isolation chip and a DC-DC isolation power supply module, with an isolation withstand voltage ≥2500Vrms; The isolated network security transmission module supports TCP / IP, UDP, and Modbus TCP protocols, and supports AES-128 or AES-256 encrypted transmission, as well as CRC32 or MD5 checksums.

8. An electromagnetic safety data acquisition system downhole according to claim 7, characterized in that: The intrinsically safe side uses a low-power ARM Cortex-M series MCU, while the non-safe side uses an industrial-grade network processor; all power and signal interfaces on the intrinsically safe side are equipped with intrinsically safe certified isolation barriers or protection circuits.

9. An electromagnetic safety data acquisition system downhole as defined in claim 1, wherein: The power module is arranged sequentially along the power flow direction as follows: a front-stage EMI filter rectifier circuit, a full-bridge topology PWM controlled high-frequency isolation transformer, a rear-stage synchronous rectification and precision voltage regulation circuit, and a linear voltage regulator. The power supply output terminal of the linear regulator is electrically connected to the power supply input terminal of the electromagnetic signal time-frequency acquisition module and the isolated network security transmission module, respectively.

10. An electromagnetic safety data acquisition system downhole according to claim 9, characterized in that: The power module is equipped with a dual intrinsically safe protection circuit combining current limiting, voltage limiting, and fuses, with a protection response time of <10μs, meeting the GB / T17626 electromagnetic compatibility standard.

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