Communication system for ultra-long-distance underground environment

Abstract

The invention discloses an ultra-long distance underground environment communication system, which comprises an underground end module, a transmission link and a ground end module, and is characterized in that dynamic impedance matching units arranged in the transmission link at intervals can track and compensate cable characteristic impedance drift in real time, and restrain a reflection coefficient below 0.1; the front and back cascaded equalization shaping units realize dynamic compensation and signal sharpening of high-frequency loss and waveform distortion based on FFT frequency response analysis and an LMS adaptive algorithm respectively; the common-mode rejection ratio of the system is not lower than 30dB by combining high-voltage-resistant magneto-optical isolation and multi-stage anti-surge protection, and each unit at the front end is dynamically adjusted according to a real-time bit error rate monitoring result under the unified scheduling of a digital signal processing unit, so that an ultra-long-distance underground transmission environment of more than 10km is finally realized, and the real-time monitoring of the bit error rate is realized. And a relatively low bit error rate and long-term stable communication are effectively ensured.

Description

Technical Field

[0001] This invention belongs to the field of downhole remote communication technology, specifically relating to a communication system for ultra-long-distance downhole environments. Background Technology

[0002] In applications such as oil drilling, coal mining, geothermal well development, and underground tunnel engineering, the underground environment is complex and variable. This necessitates the real-time transmission of data collected by sensors (such as temperature sensors, pressure sensors, vibration sensors, and gas concentration sensors) distributed deep within the wellbore or tunnels to a ground monitoring center to support remote monitoring, safety warnings, equipment control, and data analysis. Existing long-distance communication systems generally face the following technical challenges in ultra-long-distance transmission:

[0003] Signal attenuation and distortion: Over ultra-long distances, transmission media (such as cables) experience power loss due to conductor resistance, high-frequency component leakage due to distributed capacitance, and frequency response distortion introduced by distributed inductance. These factors lead to pulse signal broadening, slower leading edges, and increased inter-symbol interference; analog signal amplitude decreases significantly, signal-to-noise ratio (SNR) decreases, and it is easily overwhelmed by downhole electromagnetic noise (such as transient interference generated by motor startup). Existing solutions mostly use a single amplifier for compensation, but they cannot adapt to dynamic frequency response changes, resulting in limited transmission distance.

[0004] Impedance mismatch and signal reflection: When the characteristic impedance of the downhole equipment interface, transmission cable, and surface equipment interface is mismatched, the signal is partially reflected at the impedance abrupt change point, forming a standing wave effect, causing waveform ringing, distortion, and an increase in data error rate. Traditional methods only add fixed resistors at the terminals, which cannot cope with real-time changes in link parameters (such as impedance drift caused by temperature).

[0005] Common-mode interference and ground loop interference: There is often a ground potential difference of tens to hundreds of volts between the underground and surface areas. This potential difference is coupled through the cable shielding layer or ground wire to form a common-mode voltage, which may be converted into differential-mode interference. Simultaneously, when cables are laid in parallel with power lines (such as high-voltage power lines), power frequency (50Hz / 60Hz) interference, harmonic coupling, and electromagnetic pulses are introduced. This not only affects data transmission accuracy but may also cause interface circuit burnout or system collapse. Existing isolation technologies (such as single optical isolation) have limited suppression effects in high-interference environments, with attenuation typically less than 30dB.

[0006] Existing technical solutions often optimize only a single problem, such as improving cable shielding performance or adding simple gain devices, but they cannot comprehensively address signal quality, anti-interference capabilities, and environmental adaptability. This results in insufficient transmission stability, high bit error rate, and short system lifespan in practical ultra-long-distance downhole applications. Therefore, there is an urgent need for a highly reliable communication system that integrates multi-level compensation mechanisms to achieve collaborative optimization. Summary of the Invention

[0007] To address the aforementioned issues, this invention provides a communication system for ultra-long-distance downhole environments, significantly improving the real-time performance, stability, and long-term operational reliability of data transmission, ensuring a low bit error rate over transmission distances exceeding 10km, and adapting to harsh downhole environments.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a communication system for ultra-long-distance downhole environments, characterized in that it includes a downhole terminal module, a transmission link, and a ground terminal module.

[0009] The downhole module includes a signal acquisition unit, a primary equalization and shaping unit, a first isolation unit, and a surge protection unit. The signal acquisition unit is used to acquire sensor data from downhole and organize it into a standardized signal for transmission to the primary equalization and shaping unit. The primary equalization and shaping unit compensates for high-frequency loss and waveform broadening in real time according to the link frequency response characteristics, thereby outputting pre-compensated signal data. The first isolation unit and the surge protection unit work together to provide electrical isolation and common-mode suppression for the pre-compensated signal data.

[0010] The transmission link connects the downhole module and the surface module respectively, and transmits the pre-compensated signal data to the surface module. Dynamic impedance matching units for adjusting the link impedance are set at intervals on the transmission link.

[0011] The ground-end module includes a secondary equalization and shaping unit, a digital signal processing unit, and a terminal impedance matching unit. The terminal impedance matching unit is located at the end of the transmission link to adjust the impedance at the end of the link. The secondary equalization and shaping unit receives the signal data passing through the terminal impedance matching unit and performs adaptive compensation and repair on the signal data. The digital signal processing unit receives the signal data passing through the secondary equalization and shaping unit, compares it with historical signal data and expected signal data, calculates the real-time bit error rate, and dynamically adjusts each unit of the front end based on the bit error rate.

[0012] Furthermore, the primary equalization and shaping unit is equipped with a programmable filter and an adjustable gain amplifier. The programmable filter performs FFT frequency response analysis on the signal data of the link and adaptively compensates for the weakened high-frequency components of the signal data. The adjustable gain amplifier adjusts the gain of the input signal amplitude according to the preset target signal amplitude, and its adjustment range is 0~60dB.

[0013] Furthermore, the first isolation unit uses a combination of magnetic isolators and optical isolators connected in series with a common-mode choke to isolate and purify the pre-compensated signal data. The magnetic isolator is used to block ground loop current, and the optical isolator is used to block the conduction path of high voltage and transient spikes. The combination of magnetic isolators and optical isolators achieves electrical isolation withstand voltage ≥2kV. The common-mode choke suppresses common-mode interference introduced by transmission cable coupling and attenuates 50Hz power frequency and its harmonics by no less than 30dB.

[0014] Furthermore, the surge protection unit is used to clamp and absorb transient overvoltages and overcurrents intruding from the transmission link in multiple stages, and is composed of transient suppression diodes, gas discharge tubes and metal oxide varistors connected in series and parallel to form a multi-stage protection structure.

[0015] Furthermore, the dynamic impedance matching unit includes a digital potentiometer and a switched capacitor array, and the adjustable resistance of the digital potentiometer can be adjusted... and the compensation capacitor selected by the switch array Size, making <0.1, The reflection coefficient is used, and the terminal impedance matching unit has the same structure as the dynamic impedance matching unit.

[0016] Furthermore, the secondary equalization and shaping unit is equipped with a programmable filter and an adjustable gain amplifier. The programmable filter of the secondary equalization and shaping unit adjusts the filter coefficient in real time through the LMS adaptive algorithm. Minimize mean square error This compensates for high-frequency loss in ground-end signal data and sharpens signal edges. The adjustable gain amplifier adjusts the gain of the input signal amplitude according to the preset target signal amplitude, with an adjustment range of 0~60dB. The iterative formula of the LMS adaptive algorithm is as follows:

[0017]

[0018] Let be the coefficient vector of the filter at time n. Step size, The input signal vector.

[0019] Furthermore, the transmission link uses low-loss shielded twisted-pair cable or special mining cable.

[0020] Compared with existing technologies, the advantages of this invention are as follows: This invention effectively solves the key problems of signal attenuation, impedance mismatch, and common-mode interference by integrating a dynamic impedance matching unit, first-stage and second-stage adaptive equalization and shaping, magneto-optical dual isolation for interference suppression, and an intelligent closed-loop feedback mechanism into a collaborative processing system. Specifically, the dynamic impedance matching unit, segmented in the transmission link, can track and compensate for cable characteristic impedance drift in real time, suppressing the reflection coefficient to below 0.1; the cascaded equalization and shaping units, based on FFT frequency response analysis and LMS adaptive algorithms respectively, achieve dynamic compensation and signal sharpening for high-frequency loss and waveform distortion; combined with high-voltage magneto-optical isolation and multi-stage surge protection, the system's common-mode rejection ratio is no less than 30dB; and under the unified scheduling of the digital signal processing unit, the various front-end units are dynamically adjusted based on real-time bit error rate monitoring results, ultimately achieving effective low bit error rate and long-term stable communication in underground transmission environments with distances exceeding 10km. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings:

[0022] Figure 1 This is a schematic diagram of the system framework of the present invention; Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The following specific embodiments may be combined or substituted with each other according to the actual situation, and the same or similar concepts or processes may not be described again in some embodiments.

[0025] Example 1

[0026] like Figure 1 As shown, this invention provides a communication system for ultra-long-distance downhole environments, including a downhole terminal module, a transmission link, and a ground terminal module.

[0027] The downhole module includes a signal acquisition unit, a primary equalization and shaping unit, a first isolation unit, and a surge protection unit. The signal acquisition unit is used to acquire sensor data from downhole and organize it into a standardized signal for transmission to the primary equalization and shaping unit. The primary equalization and shaping unit compensates for high-frequency loss and waveform broadening in real time according to the link frequency response characteristics, thereby outputting pre-compensated signal data. The first isolation unit and the surge protection unit work together to provide electrical isolation and common-mode suppression for the pre-compensated signal data.

[0028] The transmission link connects the downhole module and the surface module respectively, and transmits the pre-compensated signal data to the surface module. Dynamic impedance matching units for adjusting the link impedance are set at intervals on the transmission link.

[0029] The ground-end module includes a secondary equalization and shaping unit, a digital signal processing unit, and a terminal impedance matching unit. The terminal impedance matching unit is located at the end of the transmission link to adjust the impedance at the end of the link. The secondary equalization and shaping unit receives the signal data passing through the terminal impedance matching unit and performs adaptive compensation and repair on the signal data. The digital signal processing unit receives the signal data passing through the secondary equalization and shaping unit, compares it with historical signal data and expected signal data, calculates the real-time bit error rate, and dynamically adjusts each unit of the front end based on the bit error rate.

[0030] Specifically, the primary equalization and shaping unit is equipped with a programmable filter and an adjustable gain amplifier. The programmable filter performs FFT frequency response analysis on the link's signal data and adaptively compensates for the weakened high-frequency components of the signal data. It is understood that the high-frequency components of the signal data attenuate much more than the low-frequency components during transmission. This causes the rapid rise or fall edges of the digital signal to slow down, the pulse to widen, and ultimately leads to inter-symbol interference, causing bit errors. The programmable filter, through FFT frequency response analysis, accurately plots which frequencies of the link are attenuated and how much, thereby providing greater gain in the high-frequency part with large attenuation and less gain in the low-frequency part with small attenuation, so that the frequency response of the signal becomes flat across the entire effective bandwidth. The adjustable gain amplifier adjusts the gain of the input signal amplitude according to the preset target signal amplitude, and its adjustment range is 0~60dB.

[0031] Specifically, there may be a grounding potential difference of tens to hundreds of volts between the downhole module and the surface module. If the two are not electrically isolated, this potential difference will form a huge "ground loop current" that flows through the transmission link. Therefore, the first isolation unit uses a combination of magnetic isolators and optical isolators in series with a common-mode choke to isolate and purify the pre-compensated signal data. The magnetic isolator is used to block the ground loop current, and the optical isolator is used to block the conduction path of high voltage and transient spikes. The combination of magnetic isolators and optical isolators achieves electrical isolation withstand voltage ≥2kV. The common-mode choke suppresses common-mode interference introduced by the coupling of the transmission cable and attenuates the 50Hz power frequency and its harmonics by no less than 30dB.

[0032] Specifically, since the first isolation unit has limited capacity to withstand single extremely high energy surges, a surge protection unit is needed for further protection. The surge protection unit is used to clamp and absorb transient overvoltages and overcurrents intruding from the transmission link in multiple stages. It is composed of transient suppression diodes, gas discharge tubes, and metal oxide varistors connected in series and parallel to form a multi-stage protection structure. The gas discharge tube is used to discharge high-energy surge currents, the metal oxide varistor is used to absorb medium-energy overvoltages, and the transient suppression diode is used to clamp residual voltages accurately and quickly.

[0033] Specifically, the transmission link uses low-loss shielded twisted-pair cable or special mining cable. Multiple dynamic impedance matching units are installed on the transmission link, with nodes spaced 1–5 km apart. The locations are determined based on initial measurement results. Each dynamic impedance matching unit includes a digital potentiometer and a switched capacitor array. The adjustable resistance of the digital potentiometer is adjusted... and the compensation capacitor selected by the switch array Size, making <0.1, The reflection coefficient is used. The terminal impedance matching unit has the same structure as the dynamic impedance matching unit. The calculation formula is:

[0034]

[0035] in It is the characteristic impedance of the transmission link, which is an inherent property determined by the physical structure of the transmission link (conductor size, spacing, insulation material). The dynamic impedance matching unit needs to present a new impedance; the purpose of the dynamic impedance matching unit is to adjust the adjustable resistance of the digital potentiometer. and the compensation capacitor selected by the switch array Size, so that infinitely close Furthermore, the dynamic impedance matching unit can also reduce the VSWR, stabilize the Manchester signal zero position, and enable the link to approximate a segmented cascaded coaxial line model, thereby improving the overall equalization effect.

[0036] Specifically, the secondary equalization and shaping unit is equipped with a programmable filter and an adjustable gain amplifier. The programmable filter of the secondary equalization and shaping unit adjusts the filter coefficient in real time through the LMS adaptive algorithm. Minimize mean square error This compensates for high-frequency loss in ground-end signal data and sharpens signal edges. The adjustable gain amplifier adjusts the gain of the input signal amplitude according to the preset target signal amplitude, with an adjustment range of 0~60dB. The iterative formula of the LMS adaptive algorithm is as follows:

[0037]

[0038] Let be the coefficient vector of the filter at time n. Step size, Let be the input signal vector. The error signal at time n is obtained by dn-yn, where dn is the expected response signal at time n, and yn is the output signal of the filter at time n.

[0039] The purpose of the secondary equalization and shaping unit is to provide final, adaptive compensation and repair for signals that have suffered severe attenuation and distortion after ultra-long-distance transmission. It focuses on addressing residual damage at the end of the link, sharpening the signal waveform, and preparing for reliable data decision-making.

[0040] In summary, this invention effectively solves the key challenges of signal attenuation, impedance mismatch, and common-mode interference by integrating a dynamic impedance matching unit, first-stage and second-stage adaptive equalization and shaping, magneto-optical dual isolation for interference suppression, and an intelligent closed-loop feedback mechanism into a collaborative processing system. Specifically, the dynamically matched impedance unit, segmented throughout the transmission link, can track and compensate for cable characteristic impedance drift in real time, suppressing the reflection coefficient to below 0.1. The cascaded equalization and shaping units, based on FFT frequency response analysis and LMS adaptive algorithms respectively, achieve dynamic compensation for high-frequency losses and waveform distortion, as well as signal sharpening. Combined with high-voltage magneto-optical isolation and multi-stage surge protection, the system's common-mode rejection ratio is no less than 30dB. Under the unified scheduling of the digital signal processing unit, and based on real-time bit error rate monitoring results, the various front-end units are dynamically adjusted, ultimately achieving low bit error rates and long-term stable communication in underground transmission environments exceeding 10km.

[0041] In addition to the preferred embodiments described above, the present invention has other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection claimed by the present invention.

Claims

1. A communication system for ultra-long-distance downhole environments, characterized in that, Includes downhole module, transmission link and ground module, The downhole module includes a signal acquisition unit, a primary equalization and shaping unit, a first isolation unit, and a surge protection unit. The signal acquisition unit is used to acquire sensor data from downhole and organize it into a standardized signal for transmission to the primary equalization and shaping unit. The primary equalization and shaping unit compensates for high-frequency loss and waveform broadening in real time according to the link frequency response characteristics, thereby outputting pre-compensated signal data. The first isolation unit and the surge protection unit work together to provide electrical isolation and common-mode suppression for the pre-compensated signal data. The transmission link connects the downhole module and the surface module respectively, and transmits the pre-compensated signal data to the surface module. Dynamic impedance matching units for adjusting the link impedance are set at intervals on the transmission link. The ground-end module includes a secondary equalization and shaping unit, a digital signal processing unit, and a terminal impedance matching unit. The terminal impedance matching unit is located at the end of the transmission link to adjust the impedance at the end of the link. The secondary equalization and shaping unit receives the signal data passing through the terminal impedance matching unit and performs adaptive compensation and repair on the signal data. The digital signal processing unit receives the signal data passing through the secondary equalization and shaping unit, compares it with historical signal data and expected signal data, calculates the real-time bit error rate, and dynamically adjusts each unit of the front end based on the bit error rate.

2. The communication system for ultra-long-distance downhole environments according to claim 1, characterized in that, The primary equalization and shaping unit is equipped with a programmable filter and an adjustable gain amplifier. The programmable filter performs FFT frequency response analysis on the signal data of the link and adaptively compensates for the weakened high-frequency components of the signal data. The adjustable gain amplifier adjusts the gain of the input signal amplitude according to the preset target signal amplitude, and its adjustment range is 0~60dB.

3. A communication system for ultra-long-distance downhole environments according to claim 2, characterized in that, The first isolation unit uses a combination of magnetic isolators and optical isolators connected in series with a common-mode choke to isolate and purify the pre-compensated signal data. The magnetic isolator is used to block ground loop current, and the optical isolator is used to block the conduction path of high voltage and transient spikes. The combination of magnetic isolators and optical isolators achieves electrical isolation withstand voltage ≥2kV. The common-mode choke suppresses common-mode interference introduced by transmission cable coupling and attenuates 50Hz power frequency and its harmonics by no less than 30dB.

4. A communication system for ultra-long-distance downhole environments according to claim 3, characterized in that, The surge protection unit is used to clamp and absorb transient overvoltages and overcurrents that intrude from the transmission link in multiple stages, and is composed of transient suppression diodes, gas discharge tubes and metal oxide varistors connected in series and parallel to form a multi-stage protection structure.

5. A communication system for ultra-long-distance downhole environments according to claim 4, characterized in that, The dynamic impedance matching unit includes a digital potentiometer and a switched capacitor array. The adjustable resistance of the digital potentiometer can be adjusted... and the compensation capacitor selected by the switch array Size, making The reflection coefficient is used, and the terminal impedance matching unit has the same structure as the dynamic impedance matching unit.

6. A communication system for ultra-long-distance downhole environments according to claim 5, characterized in that, The secondary equalization and shaping unit is equipped with a programmable filter and an adjustable gain amplifier. The programmable filter of the secondary equalization and shaping unit adjusts the filter coefficient in real time through the LMS adaptive algorithm. Minimize mean square error This compensates for high-frequency loss in ground-end signal data and sharpens signal edges. The adjustable gain amplifier adjusts the gain of the input signal amplitude according to the preset target signal amplitude, with an adjustment range of 0~60dB. The iterative formula of the LMS adaptive algorithm is as follows: , Let be the coefficient vector of the filter at time n. The input signal vector.

7. A communication system for ultra-long-distance downhole environments according to claim 1, characterized in that, The transmission link uses low-loss shielded twisted-pair cable or special mining cable.

Images