Half-duplex Adaptive Communication System and Method Based on Single-core Cable

Abstract

The present invention discloses a half-duplex adaptive communication system and method based on a single-core cable. The ground control system is connected to a number of downhole instruments through a single-core armored cable respectively, and is used to adaptively adjust the power supply voltage to supply power to them. After the transmitted signal is subjected to waveform transformation, filtering, and amplification, the signal is loaded onto the single-core armored cable in a capacitive coupling manner and sent to the downhole instrument. It is also used to convert the return code signal transmitted by the downhole instrument into a TTL pulse signal, analyze the pulse signal, and convert it into a corresponding return code instruction to complete instruction confirmation. The downhole instrument is used to execute corresponding operations on the signal after receiving it. After the operations are completed, the return code signal is loaded onto the single-core armored cable in a capacitive coupling manner and sent to the ground control system. The present invention can adjust the downhole power supply voltage according to the adaptive adjustment process, automatically adjust the system decoding parameters according to the communication test results, and complete the adaptive setting of the decoding parameters.

Description

Technical Field

[0001] The present invention belongs to the technical field of data communication in oilfield logging operations, and particularly relates to a half-duplex adaptive communication system and method based on a single-core cable. Background Art

[0002] During the oilfield logging operation, in order to understand the production conditions of the production wells in the oil production wells, the ground control system needs to collect data such as the temperature, pressure, and liquid production volume of each oil layer in the oil production wells in real time. The communication data volume is large and high reliability of communication is required.

[0003] In the oil well, the internal space is limited and the communication distance is long. If the ground control system and the downhole instrument in the oil well are connected by a multi-core cable for communication, there are many connection points, the structure is complex, the communication failure rate is high, and there are also deficiencies such as high construction difficulty and high cost of the communication cable.

[0004] Therefore, it becomes extremely important to load the communication signal on the power supply bus of the ground control system and the downhole instrument to reduce the communication cable, reduce the connection complexity, and improve the communication reliability of the system. Summary of the Invention

[0005] In view of this, the main object of the present invention is to provide a half-duplex adaptive communication system and method based on a single-core cable.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] An embodiment of the present invention provides a half-duplex adaptive communication system based on a single-core cable. The system includes a ground control system and a downhole instrument. The ground control system is connected to a plurality of downhole instruments respectively through a single-core armored cable, and is used to adaptively adjust the power supply voltage to supply power to them, and after waveform transformation, filtering, and amplification of the transmitted signal, the signal is loaded on the single-core armored cable in a capacitive coupling manner and sent to the downhole instrument. It is also used to convert the return code signal transmitted by the downhole instrument into a TTL pulse signal, analyze the pulse signal, and convert it into a corresponding return code instruction to complete the instruction confirmation; the downhole instrument is used to execute the corresponding operation of the signal after receiving the signal, and after the operation is completed, the return code signal is loaded on the single-core armored cable in a capacitive coupling manner and sent to the ground control system.

[0008] In the above solution, the hardware circuit of the ground control system mainly includes a CPU processing circuit, a downhole power supply control circuit, a signal sending circuit, a decoding circuit, a gain adaptive adjustment circuit, a downhole power supply voltage AD acquisition circuit, a downhole power supply current AD acquisition circuit, and a downhole instrument power supply circuit; the CPU processing circuit is respectively connected to the downhole power supply voltage AD acquisition circuit, the downhole power supply current AD acquisition circuit, the downhole instrument power supply circuit, the signal sending circuit, the decoding circuit, and the gain adaptive adjustment circuit, the signal sending circuit and the decoding circuit are both connected to the downhole instrument power supply circuit, the downhole instrument power supply circuit is connected to the downhole power supply control circuit, and the decoding circuit is connected to the gain adaptive adjustment circuit.

[0009] In the above solution, the signal sending circuit includes a signal conversion circuit, a second-order low-pass filter circuit, and an amplification circuit. The signal conversion circuit converts the TTL square wave signal into a sawtooth wave signal. After filtering out high-frequency noise through the second-order low-pass filter circuit, the signal amplitude is amplified by the amplification circuit, and finally the signal is coupled to the bus.

[0010] In the above solution, the signal sending circuit includes a first comparator U1A, a second comparator U1B, a third comparator U2A, a fourth comparator U2B, a first resistor R1 to a thirteenth resistor R13, and a first capacitor C1 to a fifth capacitor C5. The first terminal of the first comparator U1A is connected to the Usart1_Tx signal sent by the MCU through the first capacitor C1 and the first resistor R1, the second terminal is grounded, and the third terminal is connected to the second terminal of the second comparator U1B through the third resistor R3 and the fourth resistor R4. A second resistor R2 is connected between the first and third terminals of the second comparator U1B; the first terminal of the second comparator U1B is grounded through the second capacitor C2, and the third terminal is connected to the second terminal of the third comparator U2A through the seventh resistor R7 and the eighth resistor R8. A fifth resistor R5 is connected between the first and third terminals of the second comparator U1B, and a third capacitor C3 is connected between the second and third terminals. One end of the sixth resistor R6 is connected between the second capacitor C2 and the ground, and the other end is connected to the fifth resistor R5; the first terminal of the third comparator U2A is grounded, the second terminal is grounded together with the first terminal after passing through the fifth capacitor C5, the third terminal is connected to the first terminal of the fourth comparator U2B through the eleventh resistor R11, and the other path is grounded through the tenth resistor R10 and the ninth resistor R9. A fourth capacitor C4 is connected between the second and third terminals of the third comparator U2A; the second terminal of the fourth comparator U2B is grounded through the thirteenth resistor R13, and the third terminal outputs a signal TXD. A twelfth resistor R12 is connected between the first and third terminals of the fourth comparator U2B.

[0011] In the above solution, the signal coupling circuit includes a fifth comparator U3A, a seventeenth resistor R17 to a twenty-third resistor R23, a first diode D1, an eleventh capacitor C11, a twelfth capacitor C12, and a first triode Q1. The second terminal of the fifth comparator U3A is connected to the code sending circuit through the seventeenth resistor R17, and the third terminal is connected to the first triode Q1. One path of the first triode Q1 is connected to the power supply terminal POW+ of the downhole tool through the twenty-third resistor R23 and the twenty-first resistor R21, and the other path is grounded through the twenty-second resistor R22. The first terminal of the fifth comparator U3A is connected between the twenty-third resistor R23 and the first triode Q1. The nineteenth resistor R19, the eighteenth resistor R18, and the first diode D1 are connected in parallel and series on one side of the fifth comparator U3A, and the twelfth capacitor C12 and the eleventh capacitor C11 are connected in parallel and series on the other side. Moreover, the twelfth capacitor C12 and the eleventh capacitor C11 are connected to the bus BUS+ and BUS-.

[0012] In the above solution, the decoding circuit includes an analog switch U1, a first resistor R1 to a sixth resistor R6, a first capacitor C1 to a fifth capacitor C5, an amplifying circuit U4, and a post-processing circuit. The DA terminal of the analog switch U1 accesses the return code signal JxBus of the downhole tool through the third capacitor C3, the second diode D2, the second resistor R2, and the first resistor R1. The 1A terminal is connected to the second terminal of the amplifying circuit U4 through the fourth capacitor C4, the fourth resistor R4, and the fifth resistor R5. The 2A terminal is connected to the gain adaptive adjustment circuit through the fifth capacitor C5 and the sixth resistor R6. The fifth resistor R5 is also connected to the sixth resistor R6. The other end of the second diode D2 is grounded. The first capacitor C1 is connected in parallel to the first resistor R1. The second capacitor C2 is connected in parallel to the second resistor R2. The third resistor R3 is connected in parallel to the second diode D2. The first terminal of the amplifying circuit U4 is grounded, and the third terminal is connected to the gain adaptive adjustment circuit on one path and the post-processing circuit on the other path.

[0013] In the above solution, the gain adaptive adjustment circuit includes a second chip U2, an eleventh capacitor C11 to a fourteenth capacitor C14, and a seventeenth resistor R17 to a twentieth resistor R20. A twentieth resistor R20 is connected in parallel between the S1 and D1 terminals of the second chip U2, the S2 terminal is connected to the D1 terminal, a nineteenth resistor R19 is connected in parallel between the D1 and D2 terminals, the S3 terminal is connected to the D2 terminal, an eighteenth resistor R18 is connected in parallel between the D2 and D3 terminals, the S3 terminal is connected to the D2 terminal, the S4 terminal is connected to the D3 terminal, a seventeenth resistor R17 is connected in parallel between the D3 and D4 terminals. A fourteenth capacitor C14 is connected in parallel to the twentieth resistor R20, a thirteenth capacitor C13 is connected in parallel to the nineteenth resistor R19, a twelfth capacitor C12 is connected in parallel to the eighteenth resistor R18, an eleventh capacitor C11 is connected in parallel to the seventeenth resistor R17. One end of the eleventh capacitor C11 is connected to the decoding circuit, and one end of the fourteenth capacitor C14 is connected to the decoding circuit.

[0014] An embodiment of the present invention further provides a communication method for a half-duplex adaptive communication system based on a single-core cable as described in any one of the above solutions, characterized in that the method is as follows:

[0015] The ground control system performs AD acquisition to obtain a sampling value;

[0016] Adjust the power supply voltage of the downhole instrument according to the number of downhole instruments and the AD sampling value;

[0017] Adaptive adjustment of decoding parameters is performed, and handshake communication tests are carried out with the downhole instrument in multiple rounds of polling;

[0018] After successful communication, the ground control system automatically adjusts the system decoding parameters and saves the parameters.

[0019] Compared with the prior art, in the present invention, the ground control system and the downhole instrument achieve power supply and two-way communication only through the power line and the ground wire, reducing the system complexity. The downhole instrument can be connected to the ground control system through a single-core cable plug, which is especially suitable for the environment of oil wells. After the ground control system is powered on, it can adaptively adjust the downhole power supply voltage according to the adjustment process to meet the voltage required for the normal operation of the downhole instrument. The system decoding parameters are automatically adjusted according to the communication test results to complete the adaptive setting of the decoding parameters, and the anti-interference ability is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to disclose a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0021] Figure 1 is a schematic connection diagram of a half-duplex communication system based on a single-core cable provided by the present invention.

[0022] Figure 2 This is the coding circuit diagram provided by the present invention.

[0023] Figure 3 This is the circuit diagram of the coding signal coupling part provided by the present invention.

[0024] Figure 4 This is the waveform diagram of the square wave pulse signal sent by the MCU of the ground control system provided by the present invention.

[0025] Figure 5 This is the waveform diagram of converting the square wave signal into a sawtooth wave provided by the present invention.

[0026] Figure 6 This is the waveform diagram of the sawtooth wave after passing through the filter circuit and amplifier circuit provided by the present invention.

[0027] Figure 7 This is the waveform diagram of the coupling on the bus provided by the present invention.

[0028] Figure 8 This is the schematic diagram of the partial decoding circuit provided by the present invention.

[0029] Figure 9 This is the schematic diagram of the decoding gain adaptive circuit provided by the present invention.

[0030] Figure 10 This is the flowchart of the adaptive adjustment of decoding parameters provided by the present invention.

[0031] Figure 11 This is the connection diagram of each module of the ground control system provided by the present invention. Detailed implementation manners

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationships in the accompanying drawings are only for illustrative purposes and cannot be construed as limitations on this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0034] It should be noted that in this article, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, such that a process, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the presence of additional identical elements in the process, article or device comprising such element.

[0035] A half-duplex adaptive communication system based on a single-core cable according to the present invention, as Figure 1 shown, the system includes a ground control system and downhole instruments. The ground control system is respectively connected to a plurality of downhole instruments through a single-core armored cable, used to adaptively adjust the power supply voltage to supply power to them, and after waveform transformation, filtering, and amplification of the transmitted signal, the signal is loaded onto the single-core armored cable in a capacitive coupling manner and sent to the downhole instruments, and is also used to convert the return code signal transmitted by the downhole instruments into a TTL pulse signal, analyze the pulse signal, and convert it into a corresponding return code instruction to complete instruction confirmation; the downhole instruments are used to perform corresponding operations on the signal after receiving it, and after the operation is completed, load the return code signal onto the single-core armored cable in a capacitive coupling manner and send it to the ground control system.

[0036] The hardware circuit of the ground control system mainly includes a CPU processing circuit, a downhole power supply control circuit, a code sending circuit, a decoding circuit, a gain adaptive adjustment circuit, a downhole power supply voltage AD acquisition circuit, a downhole power supply current AD acquisition circuit, and a downhole instrument power supply circuit.

[0037] The CPU processing circuit is respectively connected to the downhole power supply voltage AD acquisition circuit, the downhole power supply current AD acquisition circuit, the downhole instrument power supply circuit, the code sending circuit, the decoding circuit, and the gain adaptive adjustment circuit. The code sending circuit and the decoding circuit are both connected to the downhole instrument power supply circuit. The downhole instrument power supply circuit is connected to the downhole power supply control circuit. The decoding circuit is connected to the gain adaptive adjustment circuit.

[0038] The code sending circuit includes a signal conversion circuit, a second-order low-pass filter circuit, and an amplification circuit. The signal conversion circuit converts the TTL square wave signal into a sawtooth wave signal, and after filtering out high-frequency noise through the second-order low-pass filter circuit, the signal amplitude is amplified through the amplification circuit, and finally the signal is coupled onto the bus.

[0039] The code sending circuit includes a first comparator U1A, a second comparator U1B, a third comparator U2A, a fourth comparator U2B, a first resistor R1 to a thirteenth resistor R13, and a first capacitor C1 to a fifth capacitor C5. The first terminal of the first comparator U1A is connected to the Usart1_Tx signal sent by the MCU through the first capacitor C1 and the first resistor R1, the second terminal is grounded, and the third terminal is connected to the second terminal of the second comparator U1B through the third resistor R3 and the fourth resistor R4. A second resistor R2 is connected between the first and third terminals of the first comparator (U1A); the first terminal of the second comparator U1B is grounded through the second capacitor C2, and the third terminal is connected to the second terminal of the third comparator U2A through the seventh resistor R7 and the eighth resistor R8. A fifth resistor R5 is connected between the first and third terminals of the second comparator U1B, and a third capacitor C3 is connected between the second and third terminals. One end of the sixth resistor R6 is connected between the second capacitor C2 and the ground, and the other end is connected to the fifth resistor R5; the first terminal of the third comparator U2A is grounded, the second terminal is grounded together with the first terminal after passing through the fifth capacitor C5, the third terminal is connected to the first terminal of the fourth comparator U2B through the eleventh resistor R11, and the other path is grounded after passing through the tenth resistor R10 and the ninth resistor R9. A fourth capacitor C4 is connected between the second and third terminals of the third comparator U2A; the second terminal of the fourth comparator U2B is grounded through the thirteenth resistor R13, and the third terminal outputs the signal TXD. A twelfth resistor R12 is connected between the first and third terminals of the fourth comparator U2B.

[0040] Specifically, the Usart1_Tx signal sent by the ground control system MCU, the signal waveform is as Figure 4 shown. After passing through the integrating circuit U1A, the TTL square wave signal is converted into a sawtooth wave signal, and the signal waveform is as Figure 5 shown. After passing through two Sallen-Key second-order low-pass filter circuits composed of U1B and U2A, high-frequency noise is filtered out. The zero-frequency gain of the filter circuit is A = 1 + R5 / R6. Then, the signal amplitude is amplified by the amplifier circuit U2B, and its amplification factor is A = 1 + R12 / R11. Figure 6 is the waveform after passing through the amplifier circuit U2B. At this time, this signal can be coupled to the bus.

[0041] The code sending signal coupling circuit includes a fifth comparator U3A, a seventeenth resistor R17 to a nineteenth resistor R19, a twenty-first resistor R21 to a twenty-third resistor R23, a first diode D1, a fifteenth capacitor C15, a sixteenth capacitor C16, and a first triode Q1. The second terminal of the fifth comparator U3A is connected to the code sending circuit via the seventeenth resistor R17, and the third terminal is connected to the first triode Q1. One path of the first triode Q1 is connected to the downhole tool power supply terminal POW+ via the twenty-third resistor R23 and the twenty-first resistor R21, and the other path is grounded via the twenty-second resistor R22. The first terminal of the fifth comparator U3A is connected between the twenty-third resistor R23 and the first triode Q1. The series-connected nineteenth resistor R19, eighteenth resistor R18, and first diode D1 are connected in parallel between the bus POW+ and GND. The series-connected sixteenth capacitor C16 and fifteenth capacitor C15 are connected in parallel between the bus BUS+ and BUS-.

[0042] Specifically, the signal amplified by the pre-stage code sending circuit U2B passes through Figure 3 R17 and R18 in the shown circuit diagram, and then through C15 and C16 in the coupling circuit to couple the signal for transmission on the bus. The waveform between the bus BUS+ and BUS- is as Figure 7 shown.

[0043] The decoding circuit includes an analog switch U1, a twenty-eighth resistor R28 to a thirty-third resistor R33, a sixth capacitor C6 to a tenth capacitor C10, an amplifying circuit U4, and a post-stage processing circuit. The DA terminal of the analog switch U1 is connected to the return code signal JxBus of the downhole tool via the eighth capacitor C8, the second diode D2, the twenty-ninth resistor R29, and the twenty-eighth resistor R28. The 1A terminal of the analog switch U1 is connected to the second terminal of the amplifying circuit U4 via the ninth capacitor C9, the thirty-first resistor R31, and the thirty-second resistor R32. The 2A terminal of the analog switch U1 is connected to the gain adaptive adjustment circuit via the tenth capacitor C10 and the thirty-third resistor R33. The thirty-second resistor R32 is also connected to the thirty-third resistor R33. The other end of the second diode D2 is grounded. The sixth capacitor C6 is connected in parallel on the twenty-eighth resistor R28. The seventh capacitor C7 is connected in parallel on the twenty-ninth resistor R29. The thirtieth resistor R30 is connected in parallel on the second diode D2. The first terminal of the amplifying circuit U4 is grounded, and the third terminal is connected to the gain adaptive adjustment circuit on one path and the post-stage processing circuit on the other path.

[0044] Specifically, when the downhole tool receives the instruction from the ground control system, after performing the corresponding operations, and then sends the return code signal to the power bus in the same way, the ground control system decodes the circuit Figure 8The capacitors C6 and C7 in it send the return code signal on the bus to the input end of the analog switch U1, and then after being output by the analog switch, it is sent into the U4 amplifier circuit to amplify the amplitude of the return code signal. Among them, Gain_1 and Gain_2 of the U4 amplifier circuit are gain input interfaces, and the gain can be adaptively adjusted.

[0045] After the return code signal is amplified by U4, it is input to subsequent filtering, following, threshold comparison and other subsequent processing, and the return code signal is transformed into a square wave pulse signal and sent to the IO input capture pin of the ground control system MCU.

[0046] The gain adaptive adjustment circuit includes the second chip U2, the eleventh capacitor C11 to the fourteenth capacitor C14, the twenty-fourth resistor R24 to the twenty-seventh resistor R27. A twenty-seventh resistor R27 is connected in parallel between the S1 and D1 terminals of the second chip U2, the S2 terminal is connected to the D1 terminal, a twenty-seventh resistor R27 is connected in parallel between the D1 and D2 terminals, the S2 terminal is connected to the D1 terminal, a twenty-sixth resistor R26 is connected in parallel between the D1 and D2 terminals, the S3 terminal is connected to the D2 terminal, a twenty-fifth resistor R25 is connected in parallel between the D2 and D3 terminals, the S4 terminal is connected to the D3 terminal, a twenty-fourth resistor R24 is connected in parallel between the D3 and D4 terminals. A fourteenth capacitor C14 is connected in parallel on the twenty-seventh resistor R27, a thirteenth capacitor C13 is connected in parallel on the twenty-sixth resistor R26, a twelfth capacitor C12 is connected in parallel on the twenty-fifth resistor R25, an eleventh capacitor C11 is connected in parallel on the twenty-fourth resistor R24. One end of the eleventh capacitor C11 is connected to the decoding circuit, and one end of the fourteenth capacitor C14 is connected to the decoding circuit.

[0047] Specifically, the MCU adjusts IN1, IN2, IN3, IN4, and by combination, changes the on-off between the S1, D1, S2, D2, S3, D3, S4, D4 of the U2 chip, and changes the impedance between Gain_1 and Gain_2. When using cables of different lengths, since the attenuation amplitude of the signal on the cable is different, the amplification factor of U4 is different. In this way, the amplification factor of the U4 circuit is adaptively changed to achieve the purpose of decoding under cables of different lengths.

[0048] An embodiment of the present invention provides a communication method for a half-duplex adaptive communication system based on a single-core cable. The method is as follows:

[0049] Step 101: The ground control system performs AD acquisition to obtain sampling values;

[0050] Specifically, when the ground control system is initially powered on after being connected to multiple downhole instruments, it is necessary to set the parameter of the number of downhole instruments connected to the ground control system.

[0051] The ground control system collects the current underground current value through the underground power supply current AD acquisition circuit.

[0052] Step 102: Adjust the power supply voltage of the downhole instrument according to the number of downhole instruments and the AD sampling value;

[0053] Specifically, the ground control system adjusts the underground power supply voltage through the underground power supply control circuit. After the adjustment is completed, it collects the current underground current value and detects whether the current of each downhole instrument after adjustment is within the normal range. If it is not within the normal range, it will continue to adjust the underground power supply voltage. Through this closed-loop feedback automatic control method, finally, the current of the downhole instrument is within the normal working range, and the power supply voltage parameters are saved.

[0054] Step 103: Adjust the decoding parameters adaptively and perform handshake communication tests with the downhole instrument through polling multiple times; after successful communication, the ground control system automatically adjusts the system decoding parameters and saves the parameters.

[0055] Specifically, since the cable lengths of each well are different, the communication parameters are also different, and the decoding parameters of different wells may be different.

[0056] After the downhole instrument is completed in on-site construction, the ground control system automatically adjusts the decoding gain. After the adjustment is completed, it performs communication tests with the downhole instrument through polling. The ground control system will adjust from the minimum decoding gain to the maximum decoding gain and record the communication success rate of this well under each decoding gain condition.

[0057] The ground control system saves the decoding gain parameters with a high communication success rate. Through the adaptive adjustment of the decoding gain parameters, the decoding parameters can be automatically adjusted to the appropriate range, and the whole process does not require manual intervention, realizing the automatic adjustment of the decoding parameters under different well conditions.

[0058] The above is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. A half-duplex adaptive communication system based on a single-core cable, characterized in that, The system includes a ground control system and downhole instruments. The ground control system is connected to a number of downhole instruments respectively through a single-core armored cable, used to adaptively adjust the power supply voltage to supply power to them, and after waveform transformation, filtering, and amplification of the transmitted signal, the signal is loaded onto the single-core armored cable in a capacitive coupling manner and sent to the downhole instruments. It is also used to convert the return code signal transmitted by the downhole instruments into a TTL pulse signal, analyze the pulse signal, and convert it into corresponding return code instructions to complete instruction confirmation; the downhole instruments are used to execute corresponding operations of the signal after receiving the signal, and after the operation is completed, the return code signal is loaded onto the single-core armored cable in a capacitive coupling manner and sent to the ground control system. The hardware circuit of the ground control system includes a CPU processing circuit, a downhole power supply control circuit, a signal sending circuit, a decoding circuit, a gain adaptive adjustment circuit, a downhole power supply voltage AD acquisition circuit, a downhole power supply current AD acquisition circuit, and a downhole instrument power supply circuit. The CPU processing circuit is respectively connected to the downhole power supply voltage AD acquisition circuit, the downhole power supply current AD acquisition circuit, the downhole instrument power supply circuit, the signal sending circuit, the decoding circuit, and the gain adaptive adjustment circuit. The signal sending circuit and the decoding circuit are both connected to the downhole instrument power supply circuit. The downhole instrument power supply circuit is connected to the downhole power supply control circuit. The decoding circuit is connected to the gain adaptive adjustment circuit. The decoding circuit includes an analog switch (U1), resistors R28 to R33, capacitors C6 to C10, an amplifier circuit (U4), and a post-stage processing circuit. The DA terminal of the analog switch (U1) is connected to the return code signal JxBus of the downhole instrument through capacitor C8, diode D2, resistor R29, and resistor R28. The 1A terminal of the analog switch (U1) is connected to the second terminal of the amplifier circuit (U4) through capacitor C9, resistor R31, and resistor R32. The 2A terminal of the analog switch (U1) is connected to the gain adaptive adjustment circuit through capacitor C10 and resistor R33. Resistor R32 is also connected to resistor R33. The other end of diode D2 is grounded. Capacitor C6 is connected in parallel with resistor R28. Capacitor C7 is connected in parallel with resistor R29. Resistor R30 is connected in parallel with diode D2. The first terminal of the amplifier circuit (U4) is grounded. The third terminal of the amplifier circuit (U4) is connected to the gain adaptive adjustment circuit on one path and to the post-stage processing circuit on the other path.

2. The half-duplex adaptive communication system based on a single-core cable according to claim 1, characterized in that The signal sending circuit includes a signal conversion circuit, a second-order low-pass filter circuit, and an amplifier circuit. The signal conversion circuit converts the TTL square wave signal into a sawtooth wave signal. After filtering out high-frequency noise through the second-order low-pass filter circuit, the signal amplitude is amplified through the amplifier circuit, and finally the signal is coupled onto the bus.

3. The half-duplex adaptive communication system based on a single-core cable according to claim 2, wherein The code sending circuit includes a first comparator (U1A), a second comparator (U1B), a third comparator (U2A), a fourth comparator (U2B), a first resistor (R1) to a thirteenth resistor (R13), and a first capacitor (C1) to a fifth capacitor (C5). The first terminal of the first comparator (U1A) is connected to the Usart1_Tx signal sent by the MCU through the first capacitor (C1) and the first resistor (R1), the second terminal is grounded, and the third terminal is connected to the second terminal of the second comparator (U1B) through the third resistor (R3) and the fourth resistor (R4). A second resistor (R2) is connected between the first and third terminals of the first comparator (U1A); the first terminal of the second comparator (U1B) is grounded through the second capacitor (C2), and the third terminal is connected to the second terminal of the third comparator (U2A) through the seventh resistor (R7) and the eighth resistor (R8). A fifth resistor (R5) is connected between the first and third terminals of the second comparator (U1B), a third capacitor (C3) is connected between the second and third terminals, one end of the sixth resistor (R6) is connected between the second capacitor (C2) and the ground, and the other end is connected to the fifth resistor (R5); the first terminal of the third comparator (U2A) is grounded, the second terminal is grounded together with the first terminal after passing through the fifth capacitor (C5), one path of the third terminal is connected to the first terminal of the fourth comparator (U2B) through the eleventh resistor (R11), and the other path is grounded after passing through the tenth resistor (R10) and the ninth resistor (R9). A fourth capacitor (C4) is connected between the second and third terminals of the third comparator (U2A); the second terminal of the fourth comparator (U2B) is grounded through the thirteenth resistor (R13), the third terminal outputs the signal TXD, and a twelfth resistor (R12) is connected between the first and third terminals of the fourth comparator (U2B).

4. The half-duplex adaptive communication system based on a single-core cable according to claim 3, wherein The gain adaptive adjustment circuit includes a second chip (U2), an eleventh capacitor (C11) to a fourteenth capacitor (C14), and a twenty-fourth resistor (R24) to a twenty-seventh resistor (R27). A twenty-seventh resistor (R27) is connected in parallel between the S1 and D1 terminals of the second chip (U2), the S2 terminal is connected to the D1 terminal, a twenty-sixth resistor (R26) is connected in parallel between the D1 and D2 terminals, the S3 terminal is connected to the D2 terminal, a twenty-fifth resistor (R25) is connected in parallel between the D2 and D3 terminals, the S4 terminal is connected to the D3 terminal, a twenty-fourth resistor (R24) is connected in parallel between the D3 and D4 terminals. A fourteenth capacitor (C14) is connected in parallel on the twenty-seventh resistor (R27), a thirteenth capacitor (C13) is connected in parallel on the twenty-sixth resistor (R26), a twelfth capacitor (C12) is connected in parallel on the twenty-fifth resistor (R25), an eleventh capacitor (C11) is connected in parallel on the twenty-fourth resistor (R24). One end of the eleventh capacitor (C11) is connected to the decoding circuit, and one end of the fourteenth capacitor (C14) is connected to the decoding circuit.

5. A communication method applied to the half-duplex adaptive communication system based on a single-core cable according to any one of claims 1-4, characterized in that, The method is as follows: The ground control system performs AD acquisition to obtain sampling values; Adjust the power supply voltage of the downhole instrument according to the number of downhole instruments and the AD sampling values; By adaptively adjusting the decoding parameters and performing handshake communication tests with the downhole tool through multiple polling operations; After successful communication, the ground control system automatically adjusts the system decoding parameters and saves the parameters. Specifically: The ground control system adjusts the decoding gain from the minimum value to the maximum value and records the communication success rate of this well under each decoding gain condition.

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