A weak signal acquisition system and method based on digital-analog physical isolation and symmetric dual-channel architecture

Abstract

The application discloses a weak signal acquisition system and method based on digital-analog physical isolation and symmetric dual-channel architecture, and belongs to the technical field of electronic measurement. In view of the problem that multiple weak signal acquisition is easily affected by digital-analog crosstalk, and the inconsistent parasitic parameters between channels lead to measurement error, the application provides a high anti-interference hardware architecture. The system comprises a mirror-symmetrical dual-channel analog front end, a main control processing, a direct communication and a host computer module; strict digital-analog ground physical isolation is adopted on the PCB layout, and the communication wiring is limited in the digital area, and a low-noise independent power supply is matched, so as to block the pollution of high-frequency digital pulses and external ground backflow to the analog area from the physical layer. The method is amplified independently after primary filtering and symmetric link, and then is digitized by the main control unit, and is packaged and transmitted, and the host computer receives the data, and executes data reconstruction and consistency alignment between channels. The application greatly suppresses the system noise and crosstalk between channels, and realizes high-fidelity independent extraction and synchronous analysis of multiple weak signals.

Description

Technical Field

[0001] This invention relates to the field of electronic measurement and signal processing technology. Specifically, it relates to a high-precision, multi-channel weak signal acquisition system for highly complex noise environments, and a data processing method that includes host computer interaction and multi-channel signal consistency alignment. Background Technology

[0002] In applications such as precision physical quantity measurement, industrial sensor network nodes, and high-precision extraction of weak signals (such as microscopic deformation and bioelectricity), the signals output by sensors often have characteristics such as weak amplitude and high source impedance. These weak signals are highly susceptible to contamination from spatial electromagnetic interference, power frequency noise, and high-frequency digital switching noise within the system.

[0003] In pursuit of miniaturization and high integration, traditional signal acquisition circuits typically integrate analog front-end conditioning circuits with a digital main control chip containing a high-speed communication interface on the same printed circuit board. However, this conventional layout often suffers from the following technical drawbacks: Firstly, ground bounce noise and high-frequency harmonics generated by high-speed digital logic switching can directly couple to the highly sensitive analog signal front-end through a shared ground or power plane, causing a sharp deterioration in the signal-to-noise ratio (SNR) of weak signals. Secondly, traditional multi-channel acquisition systems often neglect impedance and parasitic parameter matching between channels during wiring, leading to phase shifts, inconsistent transmission delays, and temperature drift differences when transmitting high-frequency or weak signals. This hardware-level inconsistency severely disrupts the synchronicity of multiple independent signals on the time axis, resulting in significant errors in subsequent signal cross-correlation and joint analysis. Furthermore, modern measurement systems often require communication with a host computer (such as a personal computer or industrial control computer) to achieve data visualization and secondary analysis. External host computers often have complex grounding networks and extremely strong switching power supply noise. If the communication link and analog link of the acquisition board are not properly planned in terms of physical space, the noise introduced by the host computer will travel directly to the acquisition core along the communication cable, completely drowning out the weak target signal.

[0004] Therefore, how to design a weak signal acquisition system with extremely low noise, extremely high channel consistency and secure communication interaction, starting from the underlying hardware topology architecture, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the technical problems of severe digital-analog crosstalk, poor multi-channel consistency, and easy introduction of noise by external communication in existing technologies, this invention proposes a weak signal acquisition system and method based on digital-analog physical isolation and a symmetrical dual-channel architecture. Through specific hardware isolation topology, absolutely symmetrical conditioning link design, and strictly demarcated communication layout, the high-fidelity synchronous extraction of multiple signals is guaranteed to the greatest extent.

[0006] The technical solution adopted in this invention is as follows: A weak signal acquisition system based on digital-analog physical isolation and a symmetrical dual-channel architecture, characterized in that it includes: a weak signal input module, configured to receive raw weak signals output from two independent external sensors, and containing a primary passive filter network to perform high-frequency noise filtering on the raw weak signals; a symmetrical dual-channel analog front-end amplification module, communicatively connected to the weak signal input module, the amplification module consisting of two sets of signal conditioning links with substantially the same circuit topology and parasitic parameters, used to perform high-precision synchronous amplification and conditioning on the two independent weak signals after filtering; a digital-analog physical isolation module, disposed on the physical carrier substrate of the system, separating the analog circuit area and the digital control area in terms of physical space and electrical connection, so as to block the transmission path of high-frequency digital ground bounce noise to the analog area; a main control digital processing module, deployed in the digital control area, bridging the acquisition of the two independent signals output from the analog circuit area, and integrating an analog-to-digital conversion unit internally, used to synchronously convert the conditioned analog signals into digital sequences and perform real-time feature extraction and data processing; A serial communication module establishes a direct electrical connection with the main control digital processing module. Based on the Universal Synchronous / Asynchronous Receiver / Transmitter (USART) protocol, it converts the dual-channel characteristic data output by the main control digital processing module into a serial data stream and transmits it externally. A host computer module establishes a bidirectional communication connection with the main control digital processing module through the serial communication module. It is used to receive and parse the serial data stream and perform graphical display, joint analysis, and persistent storage of dual-channel independent micro signals.

[0007] Preferably, the serial communication module includes transmit data lines and receive data lines directly connected to the communication pins of the main control digital processing module. The transmit data lines and receive data lines are strictly arranged within the digital control area on the physical carrier substrate and extend to the external physical interface of the system to realize bidirectional transparent transmission of baseband signals and prevent external ground noise from crossing the boundary and polluting the analog circuit area.

[0008] Preferably, the symmetrical dual-channel analog front-end amplification module includes a first signal conditioning link and a second signal conditioning link. The circuit component parameters and wiring on the physical carrier substrate of the two links are mirror-symmetrical to ensure that the phase delay and attenuation characteristics are highly consistent during dual-channel signal transmission.

[0009] Preferably, the digital-analog physical isolation module is manifested as a copper-free isolation strip on the copper-clad layer of the physical carrier substrate. This copper-free isolation strip divides the system ground plane into non-overlapping analog ground and digital ground, and the analog ground and digital ground establish a unique electrical connection only across the isolation strip through a single-point grounding impedance element.

[0010] Preferably, the system further includes a low-noise power supply network that independently powers the analog circuit region. The low-noise power supply network includes a low-dropout linear regulator unit and a multi-stage decoupling capacitor array arranged adjacent to the power supply terminals of each active analog device, configured to provide a high power supply rejection ratio.

[0011] This invention also provides a measurement method using the aforementioned weak signal acquisition system, characterized by the following steps: Step S1, acquiring two independent external weak signals to be measured through a weak signal input module, and using a primary passive filter network to filter out high-frequency clutter and environmental interference; Step S2, importing the filtered dual weak signals into a symmetrical dual-channel analog front-end amplification module, eliminating transmission parasitic differences between physical channels based on its mirror-symmetric link parameters, and performing independent and synchronous distortion-free amplification and conditioning of the dual channels; Step S3, transmitting the amplified dual analog signals across a digital-analog physical isolation module to the digital control area, during which the isolation module and a single-point grounding structure block the return flow of digital high-frequency pulses to the analog reference ground; Step S4, the main control digital processing module deployed in the digital control area uses an analog-to-digital conversion unit to perform high-precision synchronous quantization of the input dual clean analog signals, generating a digital sequence, and performing digital filtering and feature extraction based on a built-in algorithm; In step S5, the main control digital processing module packages the extracted dual-channel data into a USART protocol standard data frame and sends it to the host computer module via the direct physical link of the serial communication module. After parsing the digital sequence of the dual-channel independent signal, the host computer module extracts the amplitude correlation and phase offset features of the two signals according to the preset algorithm, dynamically calculates and applies the channel calibration coefficient, and realizes feature consistency alignment and visualization rendering when performing joint measurement and analysis of multiple independent signals.

[0012] The beneficial effects of this invention are: Ultimate noise floor control and isolation protection: The innovative digital-analog ground separation strip and independent analog power supply topology physically cut off the transmission path of high-frequency digital noise from inside the system to the analog sensitive area. Even if an external host computer introduces grounding noise through a direct serial bus, this noise is strictly confined within the digital control area due to the physical isolation strip, preventing it from contaminating the analog signal.

[0013] Highly consistent symmetrical synchronous topology: The analog front end adopts a completely symmetrical dual-channel mirror layout, completely eliminating the differences in parasitic capacitance and inductance caused by asymmetrical routing. This design ensures that the two independent weak signals have exactly the same phase delay, bandwidth response, and temperature drift characteristics during amplification and transmission, thus providing an extremely perfect hardware physical foundation for the strict synchronous acquisition and joint cross-analysis of multi-channel signals.

[0014] Highly efficient and flexible closed-loop interaction capability: By introducing direct USART communication and host computer module, the system can not only transmit high-precision and highly consistent multi-channel feature data from the bottom layer to the top for complex visualization rendering with extremely high efficiency, but also perform dynamic joint calibration between channels at the upper layer, realizing a collaborative closed loop of "high-fidelity acquisition at the bottom layer + intelligent alignment at the upper layer". Attached Figure Description

[0015] Figure 1 This is a block diagram of the overall architecture of the weak signal acquisition system in this embodiment of the invention; Figure 2 This is a circuit block diagram of the weak signal acquisition system in an embodiment of the present invention; Figure 3 This is a schematic diagram of a printed circuit board (PCB) wiring structure with digital-to-analog isolation features and symmetrical routing in an embodiment of the present invention. Figure 4 This is a physical diagram of the physical substrate (printed circuit board) of the weak signal acquisition system in this embodiment of the invention.

[0016] Figure 5 This is a schematic diagram of the human-machine interface of the host computer module when performing multi-channel joint analysis and phase-locked control in an embodiment of the present invention. Detailed Implementation

[0017] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so as to more clearly illustrate the advantages and features of the present invention and enable those skilled in the art to more easily understand the essence of the present invention. The description of specific embodiments is intended to further clarify the scope of protection of the present invention and provide a basis for defining the claims.

[0018] refer to Figures 1 to 3 The present invention provides a weak signal acquisition system based on digital-analog physical isolation and symmetrical dual-channel architecture. In the hardware implementation, the entire printed circuit board (PCB) is divided into a strictly non-interfering "analog circuit area" and a "digital control area".

[0019] I. Signal Input and Primary Passive Filtering Two independent weak target signals captured by external sensors are introduced into the system's weak signal input module through a high-reliability connector located at the edge of the circuit board. The signals first enter a passive RC low-pass filter network composed of precision multi-stage series resistors and parallel high-frequency ceramic capacitors. The main function of this network is to filter out radio frequency interference (RFI) and power frequency noise coupled in space, limit the input signal bandwidth, and prevent out-of-band high-frequency noise from causing aliasing distortion in subsequent active amplification stages.

[0020] II. Core Hardware Topology: The weak signal, after primary passive filtering, enters the symmetrical dual-channel analog front-end amplification module. For example... Figure 2 and Figure 3 As shown, the module is implemented in hardware as two completely independent signal conditioning links, used to respectively access and process two independent sensor signals. The first and second signal conditioning links exhibit a high degree of "mirror symmetry" in terms of component spatial coordinates, copper trace lengths, via numbers, and impedance matching on the physical substrate (PCB). Each link employs a high-precision operational amplifier unit with extremely low input bias current and low voltage noise density, coupled with a precise RC feedback network. This highly symmetrical physical layout brings significant electrical advantages: when performing dual-channel independent synchronous measurements, due to the highly consistent parasitic parameters of the two links, the phase shift, bandwidth attenuation, and impact of ambient temperature changes experienced by the two signals during conditioning are exactly the same. This means that the underlying hardware strictly locks the transmission error of the two channels to a consistent baseline, thereby greatly eliminating systematic crosstalk and mismatch between channels and ensuring absolute synchronization of the two signals in the time domain acquisition.

[0021] III. Key to Noise Reduction: Analog-Digital Physical Isolation Strip To address the most challenging issue of analog-digital crosstalk in mixed-signal acquisition systems, this embodiment implements thorough physical isolation in the printed circuit board's layer stack-up and copper plating design. A "copper-free physical isolation strip" spans the entire circuit board between the analog circuit area and the digital control area. This isolation strip spatially divides the circuit board's ground plane into non-overlapping analog ground (AGND) and digital ground (DGND). The two ground planes are only electrically connected at optimal locations near the analog-to-digital conversion interface via specific single-point grounding impedance elements (such as zero-ohm resistors or high-frequency ferrite beads). This structure ensures that the rapidly changing return current (ground bounce noise) generated by digital devices such as the main control chip during high-speed switching can only flow back and dissipate within the digital ground area, and absolutely cannot cross the isolation strip to contaminate the pure analog ground plane.

[0022] IV. Independent Low-Noise Power Supply Network This system features a dedicated low-dropout linear regulator (LDO) for the analog circuit area, which steps down and regulates the input power supply to generate an analog reference power supply with extremely low ripple. Furthermore, decoupling capacitor arrays are distributed near the power supply pins of each active amplifier stage, creating a local energy pool with extremely high power supply rejection ratio (PSRR), further filtering out conducted interference on the power lines.

[0023] V. Main Control Processing and Serial Communication Layout After the analog signal crosses the physical isolation zone, it enters the main control digital processing module in the digital control area. Both signals are directly fed into the high-precision analog-to-digital converter (ADC) integrated within the main control module for synchronous quantization sampling. After quantization, the main control digital processing module performs digital filtering based on a preset algorithm and packages the dual-channel feature data into a USART protocol format data frame according to a preset baud rate, which is then sent externally via the serial communication module. It is particularly important to emphasize the physical routing strategy of the communication module: the transmit data line (TX) and receive data line (RX) of the serial communication module are directly electrically connected to the main control module. To prevent grounding noise from external host computers (such as noisy PCs) from entering the acquisition system along the USART cable, this embodiment strictly stipulates that all USART-related printed traces and physical interface sockets must and can only be arranged within the "digital control area". In this way, the common-mode noise introduced by the host computer will be completely blocked by the "copper-free physical isolation band" after entering the acquisition board, and can only be attenuated in the digital ground network. Thus, the safety of the front-end analog signal is cleverly preserved without the need to add expensive digital isolation chips.

[0024] VI. Closed-Loop Interaction with the Host Computer Module The host computer module runs on a PC or mobile device and is equipped with a powerful data parsing engine and a human-computer interaction interface. In the downlink: The host computer module can send command frames to the underlying acquisition board via the USART bus to dynamically configure the sampling rate and other operating parameters of the underlying system. In the uplink: The host computer module receives the dual-channel weak signal characteristic data stream transmitted back from the underlying board in real time. After receiving and verifying the data, the host computer uses internal algorithms to calculate the amplitude and phase relationship of the two symmetrical channel signals, dynamically performing scale compensation coefficient calculation and data reconstruction. Thanks to the excellent physical consistency provided by the symmetrical layout of the underlying hardware, the host computer software can accurately draw consistent and aligned high signal-to-noise ratio time-domain waveforms and dual-channel cross-correlation spectra on the interface in real time, and complete the persistent storage of the data on disk.

[0025] The above description is merely a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural topology or equivalent process transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related weak signal measurement and multi-channel acquisition technologies, are similarly included within the scope of patent protection of the present invention.

Claims

1. A weak signal acquisition system based on digital-analog physical isolation and a symmetrical dual-channel architecture, characterized in that, include: The weak signal input module is configured to receive raw weak signals output from two independent external sensors, and includes a primary passive filter network to perform high-frequency noise filtering on the raw weak signals. A symmetrical dual-channel analog front-end amplification module is communicatively connected to the weak signal input module. The amplification module consists of two sets of signal conditioning links with substantially the same circuit topology and parasitic parameters, which are used to perform high-precision synchronous amplification and conditioning on the two independent weak signals after filtering. A digital-analog physical isolation module is installed on the physical carrier substrate of the system to separate the analog circuit area from the digital control area in terms of physical space and electrical connection, so as to block the transmission path of high-frequency digital ground bounce noise to the analog area. The main control digital processing module is deployed in the digital control area and cross-connects the dual independent signals output by the analog circuit area. It integrates an analog-to-digital conversion unit to synchronously convert the conditioned analog signal into a digital sequence and perform real-time feature extraction and data processing. The serial communication module establishes a direct electrical connection with the main control digital processing module, and converts the dual-channel characteristic data output by the main control digital processing module into a serial data stream and transmits it outward based on the Universal Synchronous / Asynchronous Transceiver (USART) protocol; The host computer module establishes a bidirectional communication connection with the main control digital processing module through the serial communication module. It is used to receive and parse the serial data stream, and perform graphical display, joint analysis and persistent storage of dual-channel independent micro signals.

2. The weak signal acquisition system according to claim 1, characterized in that, The serial communication module includes transmit and receive data lines that are directly connected to the communication pins of the main control digital processing module. The transmit and receive data lines are strictly arranged on the physical carrier substrate within the digital control area and extend to the external physical interface of the system to realize bidirectional transparent transmission of baseband signals and prevent external ground noise from crossing the boundary and polluting the analog circuit area.

3. The weak signal acquisition system according to claim 1, characterized in that, The symmetrical dual-channel analog front-end amplifier module includes a first signal conditioning link and a second signal conditioning link. The circuit component parameters and wiring on the physical carrier substrate of the two are mirror symmetrical to ensure that the phase delay and attenuation characteristics are highly consistent during dual-channel signal transmission.

4. The weak signal acquisition system according to claim 1, characterized in that, The analog-digital physical isolation module is manifested as a copper-free isolation strip on the copper layer of the physical carrier substrate. This copper-free isolation strip divides the system ground plane into non-overlapping analog ground and digital ground, and the analog ground and digital ground are only connected by a single-point grounding impedance element across the isolation strip to establish a unique electrical connection.

5. The weak signal acquisition system according to claim 1, characterized in that, It also includes a low-noise power supply network that independently powers the analog circuit region, the low-noise power supply network comprising a low-dropout linear regulator and a multi-stage decoupling capacitor array arranged adjacent to the power supply terminals of each active analog device, configured to provide a high power supply rejection ratio.

6. The weak signal acquisition system according to claim 1, characterized in that, The primary passive filter network in the weak signal input module is composed of a multi-stage series resistor and parallel capacitor network, which is used to suppress radio frequency interference and limit signal bandwidth.

7. A measurement method using the weak signal acquisition system according to any one of claims 1 to 6, characterized in that, It includes the following steps: Step S1: Two independent external weak signals to be tested are acquired through the weak signal input module, and high-frequency noise and environmental interference are filtered out using a primary passive filter network. Step S2: The filtered dual weak signals are respectively introduced into the symmetrical dual-channel analog front-end amplification module. Based on its mirror-symmetric link parameters, the transmission parasitic differences between physical channels are eliminated, and the dual-channel independent and synchronous distortion-free amplification and conditioning are performed. Step S3: The amplified dual-channel analog signal is transmitted to the digital control area across the digital-analog physical isolation module. During this transmission process, the isolation module and the single-point grounding structure block the return flow of digital high-frequency pulses to the analog reference ground. Step S4: The main control digital processing module deployed in the digital control area uses the analog-to-digital conversion unit to perform high-precision synchronous quantization of the input dual-channel pure analog signals, generate a digital sequence, and perform digital filtering and feature extraction based on the built-in algorithm. In step S5, the main control digital processing module packages the extracted dual-channel data into a USART protocol standard data frame and sends it to the host computer module via the direct physical link of the serial communication module. After the host computer module completes the frame verification, it performs data reconstruction and consistency alignment of the dual signals.

8. The measurement method according to claim 7, characterized in that, In step S5, after parsing the digital sequence of the dual-channel independent signals, the host computer module extracts the amplitude correlation and phase offset features of the two signals according to a preset algorithm, dynamically calculates and applies the channel calibration coefficient, and realizes feature alignment and visualization rendering when performing joint measurement and analysis of multiple independent signals.

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