A multi-type sensor compatible ultra-low noise signal acquisition system

Abstract

The application provides a multi-type sensor compatible ultra-low noise signal acquisition system, comprising an input driving unit, a low noise adaptive differential gain unit, an analog-digital conversion unit, a fault detection unit and a control communication unit. The application realizes an ultra-low noise signal acquisition system compatible with voltage / current / driven-free modes, adaptive to gain for large dynamic range signals and supporting multi-channel synchronous acquisition; the input driving unit of the application adaptively drives different sensors and picks up sensor output signals, meanwhile, the fault detection unit can detect sensor channel working states, then the adaptive differential gain unit amplifies the signals, the analog-digital conversion unit converts the signals into digital quantities, and then the control unit frames and sends the signals to the ground computer through a gigabit Ethernet isolation bus. The application has the advantages of high resolution, high precision, wide dynamic range, adjustable sampling rate, application to various types of sensors and the like.

Description

Technical Field

[0001] This invention relates to the field of measurement and testing technology, and specifically to an ultra-low noise signal acquisition system compatible with multiple types of sensors. Background Technology

[0002] my country's territorial waters contain abundant marine resources. The exploration and development of marine resources, as well as the monitoring of the marine environment, are receiving increasing attention.

[0003] Various types of ships are the main components of marine equipment. It is particularly important to measure the weak signal parameters of the ships themselves and the underwater environment, such as the hydrophone signals and transmitted signals required by the passive sonar system, as well as the vibration signals of various magnitudes and bandwidths required for monitoring and diagnosing the ship's navigation status.

[0004] While the main principles of the sensors used for this type of signal are similar, the signal output format, amplitude, and frequency band often differ due to the different measurement applications. In traditional measurement schemes, it is often necessary to customize the measurement channels of the acquisition system according to different types of sensors, resulting in low measurement interchangeability, high maintenance costs, and potentially affecting the combat efficiency of ships in certain situations.

[0005] Therefore, a device suitable for acquiring signals from various types of sensors is needed. Summary of the Invention

[0006] This invention addresses the signal acquisition challenges faced by ships that may simultaneously require signal acquisition from multiple sensors, such as accelerometers, microphones, and hydrophones. It provides an ultra-low noise signal acquisition system compatible with various sensor types. The system features a unified channel design, enabling it to acquire signals from multiple sensor types without sacrificing accuracy, bandwidth, or dynamic range. Furthermore, the ultra-low noise and adaptive gain design maximize the measurement signal-to-noise ratio, allowing even the same sensor to overcome sensitivity limitations and acquire more measurement information. Particularly in acquiring large dynamic signals, this invention effectively reduces the clipping of large signals or insufficient resolution of small signals caused by traditional fixed-range designs. This improves the measurement compatibility of the acquisition system, reduces maintenance costs, and contributes to increased ship efficiency.

[0007] This invention provides an ultra-low noise signal acquisition system compatible with multiple types of sensors, including an input driving unit, a low noise adaptive differential gain unit, an analog-to-digital conversion unit connected in sequence to the sensors, a fault detection unit connected to the output of the input driving unit, and a control and communication unit connected to the input driving unit, the low noise adaptive differential gain unit, the analog-to-digital conversion unit, and the fault detection unit.

[0008] The sensor can be voltage-driven, current-driven, or undriven; the sensor can have DC output or AC output.

[0009] The input drive unit can provide voltage or current power to the sensor and match the sensor output impedance with the input impedance of the low-noise adaptive differential gain unit;

[0010] The sensor's output signal is sequentially acquired, amplified, and converted from analog to digital by the input drive unit, the low-noise adaptive differential gain unit, and the analog-to-digital conversion unit. The control communication unit frames the multiple digital signals converted by the analog-to-digital conversion unit according to the format specified in the protocol and outputs them through the Ethernet interface. At the same time, it connects to the input drive unit with arithmetic logic to select the sensor driving mode, connects to the fault detection unit to indicate the channel status, and connects to the low-noise adaptive differential gain unit to perform gain adaptation.

[0011] The present invention discloses an ultra-low noise signal acquisition system compatible with multiple types of sensors. In a preferred embodiment, the input drive unit includes an isolation transformer circuit connected to the sensor output terminal, a solid-state relay circuit and a DC / AC mode switching circuit respectively connected to the isolation transformer circuit, a constant current source circuit connected to the solid-state relay circuit, and an LDO connected to the sensor.

[0012] The isolation transformer circuit is connected to the low-noise adaptive differential gain unit and the fault detection unit, while the solid-state relay circuit and the DC / AC mode switching circuit are connected to the control communication unit.

[0013] When the sensor is voltage-driven, the solid-state relay circuit is turned off under the control of the control and communication unit, and the LDO serves as the voltage source for the sensor; when the sensor is current-driven, the solid-state relay circuit switches the constant current source circuit to the current source for the sensor under the control of the control and communication unit; the DC / AC mode switching circuit switches the DC / AC output mode through the parallel relay U4 and capacitor C12; when the sensor is undriven, the LDO is turned off.

[0014] In the present invention, an ultra-low noise signal acquisition system compatible with multiple types of sensors is described. In a preferred embodiment, the isolation transformer circuit consists of an isolation transformer T1, the solid-state relay circuit includes a solid-state relay U3, and the constant current source circuit includes transistors Q1A, Q1B, Q2A, and Q2B, providing a drive current of 2 to 20mA. The LDO provides a +12V voltage as the external drive voltage for the sensor.

[0015] In the preferred embodiment of the multi-type sensor compatible ultra-low noise signal acquisition system of the present invention, ports 1 and 4 of the isolation transformer T1 are connected to the positive P and negative N of the sensor, respectively; one side of port 3 is connected to capacitor C9 and grounded, and the other side is output to the low noise adaptive differential gain unit; and port 2 is connected to port 3 of solid-state relay U3, DC / AC mode switching circuit and fault detection unit, respectively.

[0016] The solid-state relay U3 has its control signal IEPE_ENL input at port 1, its digital ground at port 2, and its constant current source circuit at port 4.

[0017] The constant current source circuit includes resistors R1 and R9, transistor Q1A and transistor Q1B connected to the power supply terminal V_IEPE, respectively; resistor R2, transistor Q2A and transistor Q2B connected to the other end of resistor R1, respectively.

[0018] The collector of transistor Q1A is connected to both resistors R1 and R9, and its base is connected to the other end of resistor R9 and the collector of transistor Q1B. The emitter is connected to the base of transistor Q1B. The emitter of transistor Q1B is connected to analog ground. The base of transistor Q2A is connected to both resistor R2 and the collector of transistor Q2B. The collector is connected to the other end of resistor R2 and resistor R1. The emitter is connected to the base of transistor Q2B. The base, emitter, and collector of transistor Q2B are all connected to resistor R10 and then connected to port 4 of solid-state relay U3.

[0019] Transistors Q1A and Q1B are both PNP type, while transistors Q2A and Q2B are both NPN type;

[0020] Relay U4 and capacitor C12 are connected in parallel. Port 1 of relay U4 is connected to resistor 18 and then to the DC / AC control signal AC / DC_CTLL output by the control communication unit. Port 2 is connected to physical ground. Ports 3 and 4 are connected to the two ends of capacitor C12, respectively. Resistor R17 is connected between port 4 of relay U4 and port 3 of isolation transformer T1. The connection between port 3 of isolation transformer T1, capacitor C12 and port 4 of relay U4 is the output terminal of the input drive unit, which is connected to the input terminal of the low-noise adaptive differential gain unit.

[0021] The present invention discloses an ultra-low noise signal acquisition system compatible with multiple types of sensors. In a preferred embodiment, a low-noise adaptive differential gain unit differentially amplifies the analog small signal output by the sensor and adaptively adjusts the circuit gain and signal amplitude. The low-noise adaptive differential gain unit includes a dual-ended fully differential input circuit and an adaptive gain circuit. The dual-ended fully differential input circuit includes a low-noise isolation operational amplifier and a fully differential circuit. The adaptive gain circuit adjusts the circuit gain and signal amplitude by controlling the gain resistance values ​​of two programmable digital resistor networks.

[0022] The present invention discloses an ultra-low noise signal acquisition system compatible with multiple types of sensors. As a preferred embodiment, the dual-ended fully differential input circuit includes low-noise isolation operational amplifiers U1A and U1B, resistors RA1A, RA1B, RA2A, RA2B, R19, R27, RA30A, RA30B, and decoupling capacitors C15, C20, C17, and C19.

[0023] Resistors R19 and R27 are connected to the output terminals of the input drive unit, respectively. The other end of resistor R19 is connected to the positive terminal of operational amplifier U1A. The negative terminal of operational amplifier U1A is connected to resistors RA30A, RA1B, and RA1A, respectively. The output terminal of operational amplifier U1A is connected to resistors RA1A and RA1C, respectively. The other end of resistor R27 is connected to the positive terminal of operational amplifier U1B. The negative terminal of operational amplifier U1B is connected to resistors RA30B, RA2B, and RA2A, respectively. The output terminal of operational amplifier U1B is connected to resistors RA2A and RA2C, respectively. The other ends of resistors RA30A and RA30B are connected together, and the other ends of resistors RA1B and RA2B are connected together. Operational amplifiers U1A and U1B are powered by LDOs. Decoupling capacitors C15 and C20 are connected to the negative terminals of the power supply ports, respectively, with the other ends grounded. Decoupling capacitors C17 and C19 are connected to the positive terminals of the power supply ports, respectively, with the other ends grounded.

[0024] The adaptive gain circuit includes low-noise operational amplifiers U6A and U6B, resistors RA1C, RA1D, RA2C, and RA2D, programmable digital resistor networks N8 and N9, and decoupling capacitors C26 and C30.

[0025] The positive terminal of op-amp U6A is connected to resistors RA1C and RA1D, the negative terminal is connected to the W port of programmable digital resistor network N8, and the output terminal is connected to the H port of programmable digital resistor network N8 and outputs to the analog-to-digital converter unit. The positive terminal of op-amp U6B is connected to resistors RA2C and RA2D, the negative terminal is connected to the W port of programmable digital resistor network N9, and the output terminal is connected to the H port of programmable digital resistor network N9 and outputs to the analog-to-digital converter unit. The other ends of resistors RA1D and RA2D are connected together. Decoupling capacitors C26 and C30 are connected to the positive terminals of the power supply ports of op-amps U6A and U6B, respectively, and the other ends are grounded.

[0026] In a preferred embodiment of the multi-sensor compatible ultra-low noise signal acquisition system described in this invention, the fault detection unit can detect open-circuit voltage and short-circuit voltage. The potential of the sensor's signal multiplexing terminal is compared with the open-circuit and short-circuit threshold voltages by comparators U2A and U2B, respectively. When the potential is greater than the open-circuit threshold voltage or less than the short-circuit threshold voltage, it is determined that the channel is in a sensor open-circuit / short-circuit state. Resistors R13, R14, and R15 in the fault detection unit are level adjustment resistors used to adjust the threshold voltage. The LDO pulls the outputs of comparators U2A and U2B to 3.3V for logic control.

[0027] In a preferred embodiment of the ultra-low noise signal acquisition system compatible with multiple types of sensors described in this invention, the fault detection unit further includes resistors R3, R4, and R12, and capacitors C6, C8, and C10.

[0028] One end of resistor R12 is connected to the output port T12 of the input drive unit, and the other end is connected in sequence to the negative input terminal of comparator U2A, the positive input terminal of comparator U2B, capacitor C10, and then connected to analog ground. The positive input terminal of comparator U2A is connected between resistors R13 and R14 for open-circuit voltage comparison; the negative input terminal of comparator U2B is connected between resistors R14 and R15 for short-circuit voltage comparison, and the other end of resistor R15 is grounded.

[0029] The output of comparator U2A is connected to resistor R3 and outputs a voltage of 3.3V. The output of comparator U2A is also connected to the control communication unit. The output of comparator U2B is connected to resistor R4 and outputs a voltage of 3.3V. The output of comparator U2B is also connected to the control communication unit.

[0030] The comparators U2A and U2B are powered by an LDO, and the positive output terminals of the power supply are connected to capacitors C6 and C8 respectively, which are then connected to analog ground.

[0031] The ultra-low noise signal acquisition system compatible with multiple types of sensors described in this invention, as a preferred embodiment, uses a 24-bit A / D converter with a built-in sampling rate of 256kSPS for analog-to-digital conversion in the analog-to-digital conversion unit.

[0032] The present invention discloses an ultra-low noise signal acquisition system compatible with multiple types of sensors. In a preferred embodiment, the control and communication unit includes an FPGA, an isolation bus, and a SoM connected in sequence. The digital signal output from the analog-to-digital converter is sent to the FPGA. The FPGA and SoM communicate via the isolation bus. The SoM transmits data outwards via an Ethernet interface according to a specified format using data transmission logic, enabling adaptive speeds of 10 / 100 / 1000Mbps. Simultaneously, the FPGA and SoM send control signals to the input drive unit to switch drive modes. The system receives signals from the fault detection unit to determine the channel status. Adaptive logic controls the low-noise adaptive differential gain unit, enabling the circuit to automatically adjust the gain according to the input signal. Furthermore, commands are sent to the analog-to-digital converter to achieve independent multi-level acquisition frequency adjustments of 6.4kHz, 12.8kHz, 25.6kHz, 51.2kHz, 102.4kHz, and 204.8kHz for each channel.

[0033] This invention is applied to the acquisition of weak signals in the context of shipboard applications.

[0034] This invention discloses an ultra-low noise signal acquisition system applicable to various types of sensors. The system is designed and implemented to be compatible with voltage / current / driveless modes, features gain adaptation for signals with a large dynamic range, and supports multi-channel synchronous acquisition. The system uses an input drive unit to adaptively drive different sensors and pick up their output signals. Simultaneously, a fault detection unit detects the operating status of sensor channels. An adaptive differential gain unit amplifies the signal, and an analog-to-digital converter converts the signal into a digital quantity. Finally, the signal is framed by a control unit and transmitted to a ground computer via a gigabit Ethernet isolated bus. This system offers advantages such as high resolution, high accuracy, wide dynamic range, adjustable sampling rate, and applicability to various sensor types.

[0035] The present invention has the following advantages:

[0036] (1) The measurement channel of this invention is compatible with voltage / current / no-drive mode and can be used for signal acquisition of various types of sensors.

[0037] (2) The analog signal acquisition circuit of this invention adopts an ultra-low noise design with a noise floor of less than 17μg, which can obtain an extremely low measurement limit and an extremely high signal-to-noise ratio, thereby obtaining a high dynamic range of more than 100dB.

[0038] (3) The present invention adopts a gain adaptive method, which automatically adjusts the gain of the pre-amplifier according to the magnitude of the input signal, which can effectively reduce the resolution loss or distortion of large dynamic range signals, and also eliminates the need for manual gain setting.

[0039] (4) This invention uses 24-bit high-resolution sampling, and each channel can be independently set with multiple sampling rates and multiple sampling modes. The data is sent via a 10 / 100 / 1000Mbps adaptive Ethernet interface, which takes into account both data accuracy and transmission efficiency. Attached Figure Description

[0040] Figure 1 This is a block diagram illustrating the principle of an ultra-low noise signal acquisition system compatible with multiple sensor types.

[0041] Figure 2 Schematic diagram of the input drive unit for an ultra-low noise signal acquisition system compatible with multiple sensor types;

[0042] Figure 3 This is a schematic diagram of a fault detection unit for an ultra-low noise signal acquisition system compatible with multiple sensor types.

[0043] Figure 4 This is a schematic diagram of a low-noise adaptive differential gain unit for an ultra-low noise signal acquisition system compatible with multiple sensor types.

[0044] Figure 5 This is a schematic diagram of the control and communication unit for an ultra-low noise signal acquisition system compatible with multiple types of sensors.

[0045] Figure label:

[0046] 1. Sensor; 2. Input drive unit; 3. Low-noise adaptive differential gain unit; 4. Analog-to-digital conversion unit; 5. Fault detection unit; 6. Control and communication unit. Detailed Implementation

[0047] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0048] Example 1

[0049] An ultra-low noise signal acquisition system compatible with multiple sensor types, such as Figure 1 As shown, the control unit includes sensor 1, input drive unit 2, low-noise adaptive differential gain unit 3, analog-to-digital converter unit 4, fault detection unit 5, and control communication unit 6. The signal from sensor 1 is sequentially acquired, amplified, and converted to digital data via input drive unit 2, low-noise adaptive differential gain unit 3, and analog-to-digital converter unit 4. Control unit 6 frames the converted multiple digital signals according to the protocol and outputs them via an Ethernet interface. Simultaneously, it connects to input drive unit 2 via arithmetic logic to select the sensor drive mode, connects to fault detection unit 5 to indicate channel status, and connects to low-noise adaptive differential gain unit 3 to achieve gain adaptation.

[0050] like Figure 2 As shown, the input drive unit 2 includes a constant current source circuit, an isolation transformer circuit, and a solid-state relay circuit. The isolation transformer circuit is composed of an isolation transformer T1 to match the sensor output impedance with the amplifier input impedance. The constant current source circuit is composed of transistors Q1A, Q1B, Q2A, and Q2B to provide a drive current of 2-20mA in the current drive mode. When powered by the current source, the sensor's power supply and output are multiplexed, i.e., the sensor's P and N pins receive current. In the voltage drive mode, an LDO provides a +12V voltage as the external drive voltage for the sensor. The two modes are switched by controlling the on / off state of the solid-state relay U3. At the same time, another relay U4 in the solid-state relay circuit can switch between DC and AC output modes.

[0051] like Figure 3 As shown, the fault detection unit 5 includes a comparison circuit and a threshold setting circuit. The potential of the sensor's signal multiplexing terminal is compared with the open-circuit and short-circuit threshold voltages by comparators U2A and U2B, respectively. When the potential is greater than the open-circuit threshold voltage or less than the short-circuit threshold voltage, it is determined that the channel is in an open-circuit / short-circuit state. Resistors R13, R14, and R15 are level adjustment resistors used to adjust the threshold voltage. A high-precision reference source pulls the comparator output to 3.3V for logic control.

[0052] like Figure 4 As shown, the adaptive differential gain unit 3 includes a low-noise differential amplifier circuit, a high-precision LDO, and a gain adaptive amplifier circuit. The adaptive differential gain unit 3 amplifies the small analog signal output from sensor 1. A dual-ended fully differential input circuit is formed using a low-noise isolated operational amplifier U1, resistors RA1, RA2, RA30, R19, R27, and decoupling capacitors C15 and C20. The high-precision LDO power supply and precision resistor network ensure the matching of the dual-ended input parameters. The fully isolated amplification and power supply design, along with appropriate PCB routing, can reduce the circuit's noise floor to below 17μg. An adaptive gain circuit is formed using a low-noise operational amplifier U6, resistors RA1 and RA2, a programmable digital resistor network N8 and N9, and decoupling capacitors C26 and C30. By controlling the gain resistor values ​​of N8 and N9, the circuit gain adapts to the signal amplitude. The low-noise adaptive differential gain unit 3 can achieve a signal-to-noise ratio of over 80dB at 0dB gain, and the circuit's dynamic range can reach over 100dB.

[0053] like Figure 5As shown, the analog-to-digital conversion unit 4 uses a 24-bit A / D converter with a built-in sampling rate of 256kSPS for analog-to-digital conversion. The control and communication unit 6 includes an FPGA, a SoM (Solar Module), and an isolated bus module. It uses control logic to complete drive mode settings, fault detection indication, adaptive gain, and gigabit Ethernet communication. The design employs an FPGA and a low-power SoM, with a high-precision reference source providing a 3.3V logic level. After analog-to-digital conversion, the analog signal is sent to the FPGA. The FPGA and SoM communicate via an isolated bus, further reducing circuit noise. The SoM transmits data via an Ethernet interface according to a specified format using data transmission logic, and can adapt to 10 / 100 / 1000Mbps. Simultaneously, through the FPGA, SoM can send control signals to the input drive unit 2 to switch the drive mode, receive signals from the fault detection unit 5 to determine the channel status, control the gain of the amplifier circuit 3 through adaptive logic so that the circuit can automatically adjust the gain according to the input signal, and complete the independent multi-level acquisition frequency adjustment of each channel (6.4kHz, 12.8kHz, 25.6kHz, 51.2kHz, 102.4kHz, 204.8kHz) by sending commands to the analog-to-digital conversion unit 4.

[0054] This embodiment is compatible with voltage / current / no-drive modes according to sensor type 1, with a dynamic range of not less than 65~175dB, bandwidth of not less than 40kHz, in-band unevenness of less than ±1dB, amplitude linearity of less than ±2dB, signal-to-noise ratio of greater than 80dB (0dB Gain), multiple sampling rates and sampling modes are available, and it has a sensor fault detection indication function.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A multi-sensor compatible ultra-low noise signal acquisition system, characterized in that: It includes an input drive unit (2), a low-noise adaptive differential gain unit (3), an analog-to-digital converter (4) connected in sequence to the sensor (1), a fault detection unit (5) connected to the output terminal of the input drive unit (2), and a control communication unit (6) connected to the input drive unit (2), the low-noise adaptive differential gain unit (3), the analog-to-digital converter (4), and the fault detection unit (5). The sensor (1) is voltage-driven, current-driven, or undriven, and the sensor (1) has DC output or AC output; The input driving unit (2) provides voltage or current power to the sensor (1) and matches the output impedance of the sensor (1) with the input impedance of the low-noise adaptive differential gain unit (3); The output signal of the sensor (1) is sequentially acquired, amplified and converted into analog and digital signals through the input driving unit (2), the low-noise adaptive differential gain unit (3) and the analog-to-digital conversion unit (4). The control communication unit (6) frames the multiple digital signals converted by the analog-to-digital conversion unit (4) according to the format specified by the protocol and outputs them through the Ethernet interface. At the same time, it connects to the input driving unit (2) with arithmetic logic to select the sensor driving mode, connects to the fault detection unit (5) to indicate the channel status, and connects to the low-noise adaptive differential gain unit (3) to perform gain adaptation. When the sensor (1) is voltage driven, the solid-state relay circuit is turned off under the control of the control communication unit (6), and the LDO serves as the voltage source of the sensor (1); when the sensor (1) is current driven, the solid-state relay circuit switches the constant current source circuit to the current source of the sensor (1) under the control of the control communication unit (6); the DC / AC mode switching circuit switches the DC / AC output mode through the parallel relay U4 and capacitor C12; when the sensor (1) is not driven, all LDOs are turned off. The low-noise adaptive differential gain unit (3) differentially amplifies the analog small signal output by the sensor (1) and adaptively adjusts the circuit gain and signal amplitude; the low-noise adaptive differential gain unit (3) includes a dual-ended fully differential input circuit and an adaptive gain circuit. The dual-ended fully differential input circuit includes a low-noise isolation operational amplifier and a fully differential circuit. The adaptive gain circuit adapts the circuit gain and signal amplitude by controlling the gain resistance values ​​of two programmable digital resistor networks. The fault detection unit (5) can detect open circuit voltage and short circuit voltage. The potential of the signal multiplexing terminal of the sensor (1) is compared with the open circuit and short circuit threshold voltages by comparators U2A and U2B respectively. When the potential is greater than the open circuit threshold voltage / less than the short circuit threshold voltage, it is determined that the channel is in the open circuit / short circuit state of the sensor.

2. The ultra-low noise signal acquisition system compatible with multiple sensor types according to claim 1, characterized in that: The input drive unit (2) includes an isolation transformer circuit connected to the output terminal of the sensor (1), a solid-state relay circuit and a DC / AC mode switching circuit respectively connected to the isolation transformer circuit, a constant current source circuit connected to the solid-state relay circuit and an LDO connected to the sensor (1). The isolation transformer circuit is connected to the low-noise adaptive differential gain unit (3) and the fault detection unit (5), and the solid-state relay circuit and the DC / AC mode switching circuit are connected to the control communication unit (6).

3. The ultra-low noise signal acquisition system compatible with multiple sensor types according to claim 2, characterized in that: The isolation transformer circuit consists of an isolation transformer T1, the solid relay circuit includes a solid relay U3, the constant current source circuit includes transistors Q1A, Q1B, Q2A, and Q2B, providing a drive current of 2~20mA; the LDO provides a +12V voltage as the external drive voltage for the sensor (1).

4. The ultra-low noise signal acquisition system compatible with multiple sensor types according to claim 3, characterized in that: Ports 1 and 4 of the isolation transformer T1 are connected to the positive P and negative N of the sensor (1) respectively. One side of port 3 is connected to capacitor C9 and grounded, and the other side is output to the low noise adaptive differential gain unit (3). Port 2 is connected to port 3 of solid relay U3, the DC / AC mode switching circuit and the fault detection unit (5) respectively. The control signal IEPE_ENL of the control communication unit (6) is input at port 1 of the solid relay U3, port 2 is connected to digital ground, and port 4 is connected to the constant current source circuit. The constant current source circuit includes resistor R1, resistor R9, and transistor Q1A connected to the power supply terminal V_IEPE, transistor Q1B connected to transistor Q1A, and resistor R2, transistor Q2A, and transistor Q2B connected to the other end of resistor R1. The collector of transistor Q1A is connected to both resistors R1 and R9, and its base is connected to the other end of resistor R9 and the collector of transistor Q1B. The emitter is connected to the base of transistor Q1B. The emitter of transistor Q1B is connected to analog ground. The base of transistor Q2A is connected to both resistor R2 and the collector of transistor Q2B. The collector is connected to the other end of resistor R2 and resistor R1. The emitter is connected to the base of transistor Q2B. The base, emitter, and collector of transistor Q2B are all connected to resistor R10 and then connected to port 4 of solid-state relay U3. Transistors Q1A and Q1B are both PNP type, while transistors Q2A and Q2B are both NPN type; Relay U4 and capacitor C12 are connected in parallel. Resistor 1 of relay U4 is connected to resistor 18 and then to the DC / AC control signal AC / DC_CTLL output by the control communication unit (6). Port 2 is connected to physical ground. Ports 3 and 4 are respectively connected to the two ends of capacitor C12. Resistor R17 is connected between port 4 of relay U4 and port 3 of isolation transformer T1. The connection between port 3 of isolation transformer T1, capacitor C12 and port 4 of relay U4 is the output of input drive unit (2), which is connected to the input of low noise adaptive differential gain unit (3).

5. The ultra-low noise signal acquisition system compatible with multiple sensor types according to claim 1, characterized in that: The dual-ended fully differential input circuit includes low-noise isolation operational amplifiers U1A and U1B, resistors RA1A, RA1B, RA2A, RA2B, R19, R27, RA30A, RA30B, and decoupling capacitors C15, C20, C17, and C19. Resistors R19 and R27 are connected to the output terminals of the input drive unit (2), and the other end of resistor R19 is connected to the positive terminal of operational amplifier U1A. The negative terminal of operational amplifier U1A is connected to resistors RA30A, RA1B, and RA1A, respectively. The output terminal of operational amplifier U1A is connected to resistors RA1A and RA1C. The other end of resistor R27 is connected to the positive terminal of operational amplifier U1B, and the negative terminal of operational amplifier U1B is connected to resistors RA30B, RA2B, and RA2A, respectively. The output terminal of operational amplifier U1B is connected to resistors RA2A and RA2C. The other ends of resistors RA30A and RA30B are connected, and the other ends of resistors RA1B and RA2B are connected. The power supply for operational amplifiers U1A and U1B is LDO. Decoupling capacitors C15 and C20 are connected to the negative terminals of the power supply port, and the other ends are grounded. Decoupling capacitors C17 and C19 are connected to the positive terminals of the power supply port, and the other ends are grounded. The adaptive gain circuit includes low-noise operational amplifiers U6A and U6B, resistors RA1C, RA1D, RA2C, and RA2D, programmable digital resistor networks N8 and N9, and decoupling capacitors C26 and C30. The positive terminal of operational amplifier U6A is connected to resistors RA1C and RA1D respectively, the negative terminal is connected to the W port of programmable digital resistor network N8, and the output terminal is connected to the H port of programmable digital resistor network N8 and output to the analog-to-digital conversion unit (4); the positive terminal of operational amplifier U6B is connected to resistors RA2C and RA2D respectively, the negative terminal is connected to the W port of programmable digital resistor network N9, and the output terminal is connected to the H port of programmable digital resistor network N9 and output to the analog-to-digital conversion unit (4). The other ends of resistors RA1D and RA2D are connected together. Decoupling capacitors C26 and C30 are connected to the positive terminals of the power supply ports of operational amplifiers U6A and U6B respectively, and the other ends are grounded.

6. The ultra-low noise signal acquisition system compatible with multiple sensor types according to claim 1, characterized in that: The resistors R13, R14, and R15 in the fault detection unit (5) are level adjustment resistors used to adjust the threshold voltage; the LDO pulls the outputs of comparators U2A and U2B to 3.3V for logic control.

7. The ultra-low noise signal acquisition system compatible with multiple sensor types according to claim 6, characterized in that: The fault detection unit (5) also includes resistors R3, R4, R12 and capacitors C6, C8, C10; One end of resistor R12 is connected to the output port T12 of the input drive unit (2), and the other end is connected in sequence to the negative input terminal of comparator U2A, the positive input terminal of comparator U2B, and capacitor C10 and then connected to analog ground. The positive input terminal of comparator U2A is connected between resistors R13 and R14 to perform open-circuit voltage comparison. The negative input terminal of comparator U2B is connected between resistors R14 and R15 for short-circuit voltage comparison, and the other end of resistor R15 is grounded. The output of comparator U2A is connected to resistor R3 and outputs a voltage of 3.3V. The output of comparator U2A is also connected to the control communication unit (6). The output of comparator U2B is connected to resistor R4 and outputs a voltage of 3.3V. The output of comparator U2B is also connected to the control communication unit (6). The comparators U2A and U2B are powered by an LDO, and the positive output terminals of the power supply are connected to capacitors C6 and C8 respectively, which are then connected to analog ground.

8. The ultra-low noise signal acquisition system compatible with multiple sensor types according to claim 1, characterized in that: The analog-to-digital conversion unit (4) uses a 24-bit A / D converter with a built-in sampling rate of 256kSPS to perform analog-to-digital conversion.

9. The ultra-low noise signal acquisition system compatible with multiple sensor types according to claim 1, characterized in that: The control communication unit (6) includes an FPGA, an isolation bus, and a SoM connected in sequence. The digital signal output by the analog-to-digital conversion unit (4) is sent to the FPGA. The FPGA and SoM communicate via the isolation bus. The SoM sends the data out through the Ethernet interface according to the format through the data transmission logic, and can be adaptive to 10 / 100 / 1000Mbps. At the same time, the FPGA and SoM send control signals to the input drive unit (2) to switch the drive mode. The signal received from the fault detection unit (5) is used to judge the channel status. The low-noise adaptive differential gain unit (3) is controlled by the adaptive logic so that the circuit can automatically adjust the gain according to the input signal. The independent 6.4kHz, 12.8kHz, 25.6kHz, 51.2kHz, 102.4kHz, and 204.8kHz acquisition frequency adjustment of each channel is completed by sending commands to the analog-to-digital conversion unit (4).

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