A 256-channel weak signal acquisition and processing device

Abstract

The application discloses a 256-channel weak signal acquisition and processing device, and relates to the field of signal processing.The device comprises a front-end signal board, a digital processing board and a programmable voltage board.The front-end signal board is used for mounting a terahertz sensor and adding a voltage bias.The digital processing board is provided with an analog-digital conversion module, and the analog-digital conversion module is provided with an acquisition channel.The programmable voltage board is used for accurately adjusting an auxiliary bias power supply for each column of pixel points, thereby improving the precision of the pixel points.In the existing scheme, the bias inductor for acquiring a bias voltage on a sensor unit is replaced by a bias resistor, which serves as a bias voltage and a blocking function, so that the device can be integrated in a small size under the condition of meeting the normal operation of the sensor, and the multi-group design of the sensor unit can avoid the failure of the entire group of sensors caused by the bias power supply failure.

Description

Technical Field

[0001] This invention relates to the field of signal processing, specifically to a 256-channel weak signal acquisition and processing device. Background Technology

[0002] Terahertz (THz) waves refer to electromagnetic waves with frequencies between 0.1 and 10 THz. This band is often referred to as the "terahertz gap" because it lies between microwaves and infrared radiation. In the terahertz band, the absorption and scattering characteristics resulting from the vibrational and rotational energy level transitions of molecules are closely related to the molecular structure and dynamics. Therefore, terahertz waves have significant applications in many fields, such as security inspection, life sciences, wireless communication, and imaging technology. Terahertz array imaging can be used for high-speed moving target detection with high resolution and is commonly used for detecting high-speed moving targets such as satellites and aircraft. A terahertz array imaging system is an array of multiple terahertz sensors that acquires information about an object by receiving its terahertz wave signals and then performs imaging. This system has two key components: the sensor array and the signal acquisition and processing. Currently, terahertz array imaging systems are still in the laboratory research stage. Existing technologies in the field of terahertz imaging suffer from weak sensor output signals and low accuracy of target signals due to large dispersion in sensor parameters. Furthermore, there is a lack of centralized processing for the transmission, amplification, and acquisition of weak signals. Meanwhile, regarding equipment, existing commonly used technologies lack mature signal acquisition and processing devices. On the one hand, terahertz array imaging systems are mainly built using discrete components. Because existing technologies primarily use large bias inductors to provide bias voltage to sensors, the modules are relatively scattered during actual assembly, making it difficult to achieve small-volume integrated design. This results in existing terahertz array imaging systems lacking a design that integrates a high number of independent channels, leading to a smaller number of pixels that can be processed simultaneously. On the other hand, because multiple sensors in the front-end probe share a single bias voltage, and the probes are susceptible to damage (manifesting as short circuits), if one probe fails and short-circuits, the bias power supply of the group of sensors sharing the probe will be pulled low to ground. Since a normal bias voltage is a prerequisite for the normal operation of the sensors, there is a risk that the entire group of sensors may become unusable. Summary of the Invention

[0003] This invention provides a 256-channel weak signal acquisition and processing device, which solves the problems in the existing technology of terahertz imaging, such as the difficulty in integrating multiple terahertz sensor devices, the weak total strength of sensor signals, and the low pixel accuracy of terahertz imaging.

[0004] This invention is achieved through the following technical solution:

[0005] A 256-channel weak signal acquisition and processing device includes a front-end signal board, a digital processing board, and a programmable voltage board. The front-end signal board is used to install a terahertz sensor and add a voltage bias, providing a bias voltage to the terahertz sensor and generating the required terahertz signal for the device, then transmitting the signal to the digital processing board. The front-end signal board has multiple signal source modules, each including a bias circuit and multiple sensor units, with the multiple sensor units within each signal source module sharing the bias voltage in the bias circuit. Each sensor unit has a first load resistor RS2 for bias voltage transmission. The digital processing board includes an analog-to-digital converter. The device comprises a module, wherein the analog-to-digital conversion module is equipped with a data acquisition channel; the digital processing board is used to receive signals through the acquisition channel using the analog-to-digital conversion module, perform preprocessing such as filtering and amplification to enhance signal detection intensity, then sample and analyze the signals through analog-to-digital conversion to obtain the frequency composition and distribution of the signals, and generate and organize pixel data; the programmable voltage board is used to generate a high-precision adjustable power supply voltage to provide a voltage source for the device, and to set an independent bias voltage for each column of sensors to improve the anti-interference capability and linearity of sensor signal transmission, while precisely adjusting the bias power supply for each column of pixels to improve pixel accuracy. In existing technologies, there are problems such as weak sensor output signals and low target signal accuracy due to large dispersion of sensor parameters, necessitating the transmission, amplification, and acquisition of weak signals. Existing technologies lack mature signal acquisition and processing devices. On one hand, they primarily rely on discrete components to build terahertz array imaging systems, resulting in fragmented modules and a lack of integrated design. On the other hand, existing terahertz array imaging systems lack a design that integrates a high number of independent channels, limiting the number of pixels that can be processed simultaneously. To address this, this invention provides a 256-channel weak signal acquisition and processing device. By integrating 256 channels into a single device and employing precise bias voltage adjustment and low-noise signal transmission processing, it solves the problems of weak terahertz sensor signal strength, low pixel accuracy in terahertz imaging, and the lack of sensor and multi-channel integrated design in existing terahertz imaging technologies.

[0006] This signal acquisition and processing device mainly consists of three parts: a front-end signal board, a digital processing board, and a programmable voltage board. The front-end signal board is used for sensor probe installation and bias voltage initialization. The digital processing board uses 256 channels to amplify and acquire weak signals and extract pixel parameters. The programmable voltage board is primarily used to provide a high-precision, adjustable voltage source. After proper biasing, the sensor on the front-end signal board can effectively detect reflected terahertz signals and convert them into weak voltage signals at the microvolt level. Therefore, in practical applications, the front-end signal board has two sets of signals: one set connected to the voltage board for inputting the probe bias voltage, and the other set connected to the digital processing board for outputting the weak voltage signal. The bias voltage output by the programmable voltage board needs to be precisely adjustable through user control; therefore, the front-end signal board has a set of digital interface signals connected to the processing board. Both the digital processing board and the programmable voltage board have power input interfaces for supplying power to the circuit.

[0007] Furthermore, the front-end signal board is provided with 16 signal source modules, each signal source module is provided with 16 sensor units, and the 16 sensor units share a bias voltage in a bias circuit.

[0008] Furthermore, the sensor unit is provided with at least one AC voltage source AC and an output resistor RS1; the bias circuit is provided with at least one DC power supply DC, a filter capacitor C1 and a DC blocking capacitor C2; the circuit on the acquisition channel is provided with at least one second load resistor RS3.

[0009] Furthermore, the digital processing board includes a first main controller, on which a signal transceiver, a first connector, a power connector, an analog-to-digital converter module, a first memory, and a second memory are connected via signal connections; a power module is connected via signal connections to the power connector; a USL connector is connected via signal connections to the acquisition channel; and a second connector is also connected via signal connections to the signal transceiver; the first connector is a QSFP connector, and the second connector is an RJ45 connector.

[0010] Furthermore, the analog-to-digital conversion module is internally equipped with a main signal link, which includes a signal attenuator, a low-noise amplifier, a filter, a first analog-to-digital converter, and a digital processing unit connected in sequence. The input end of the signal attenuator is used to receive the signal, and the output end of the digital processing unit outputs the signal.

[0011] Furthermore, the programmable voltage board includes a second main controller, a DC-DC converter, a low-voltage regulator, a current sensor, and a third connector, wherein the DC-DC converter, the low-voltage regulator, the current sensor, and the third connector are sequentially connected by signals; the second main controller is equipped with a first digital-to-analog converter, a second analog-to-digital converter, a serial port module, and a digital I / O interface module, and the output terminal of the second main controller for switch control and the output terminal of the first digital-to-analog converter for voltage control are both connected to the input terminal of the low-voltage regulator; the output terminal of the low-voltage regulator to the current sensor has a second branch for voltage acquisition, and the second branch is connected to the input terminal of the second analog-to-digital converter; the output terminal of the current sensor for current acquisition is connected to the input terminal of the second analog-to-digital converter.

[0012] Furthermore, a voltage regulator RT, a conversion resistor RDAC, and a grounding resistor RB are provided between the low-voltage regulator and the first digital-to-analog converter; the low-voltage regulator is provided with a first voltage terminal V0 and a feedback voltage terminal, and the first digital-to-analog converter is provided with a second voltage terminal V0-DAC. The V0 terminal is connected to one end of the voltage regulator RT, the V0-DAC terminal is connected to one end of the conversion resistor RDAC, the grounding terminal of the grounding resistor RB is grounded, and the other end of the voltage regulator RT, the other end of the conversion resistor RDAC, the enable terminal of the grounding resistor RB, and the feedback voltage terminal are connected to the same point; the currents of the V0 terminal, the V0-DAC terminal, the feedback voltage terminal, and the grounding resistor RB are respectively set as the first current I_RT, the second current I_DAC, the third current I_FB, and the fourth current I_RB.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0014] 1. Replace the bias inductor used to obtain the bias voltage on the sensor unit in the existing solution with a bias resistor to serve as both bias and blocking resistor. This can achieve small-size integration of the device while ensuring normal operation of the sensor. At the same time, designing multiple sensor units can prevent the entire sensor group from failing when the bias power supply fails.

[0015] 2. The weak signal emitted by the terahertz imaging sensor is divided into three parts according to the initialization preset bias voltage and the 256 multi-channel sampling amplification working module: the front-end signal board, the digital processing board, and the programmable voltage board. These parts are centrally located in the device. This enables a high degree of integration of multiple processing channels of a single signal acquisition and processing device, improves the display generation efficiency of terahertz array imaging, and enhances the convenience of terahertz array imaging work.

[0016] 3. Through the coordinated operation of the front-end signal board and the digital processing board, while the front-end signal board effectively resists external noise, the signal gain amplification of the terahertz array sensor signal can be achieved within the 256 channels built on the digital processing board, reducing the signal weakness problem in the terahertz array imaging generation process. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 This is a general schematic diagram of the structure of the data acquisition and processing device in this invention;

[0019] Figure 2 This is an equivalent circuit diagram of a single sensor unit and acquisition channel in the front-end signal board of this invention;

[0020] Figure 3 This is a circuit diagram showing the connection configuration of the sensor unit in the signal source module of the front-end signal board in this invention;

[0021] Figure 4 This is a schematic diagram of the structure of the digital processing board in this invention;

[0022] Figure 5 This is a schematic diagram of the analog-to-digital conversion module in this invention;

[0023] Figure 6 This is a schematic diagram of the programmable voltage board in this invention;

[0024] Figure 7 This is a schematic diagram of the connection structure between the low-voltage regulator and the first digital-to-analog converter in this invention. Detailed Implementation

[0025] 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 embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention. Example

[0026] like Figure 1As shown, a 256-channel weak signal acquisition and processing device includes a front-end signal board, a digital processing board, and a programmable voltage board. The front-end signal board initializes circuit parameters, installs the terahertz sensor, adds voltage bias, provides bias voltage to the terahertz sensor, generates the required terahertz signal, and transmits the signal to the digital processing board. The front-end signal board has multiple signal source modules, each including a bias circuit and multiple sensor units, with the sensor units sharing the bias voltage in the bias circuit. Each sensor unit has a first load resistor RS2 for bias voltage transmission. The digital processing board... The device is equipped with an analog-to-digital converter (ADC) module, which has a data acquisition channel. The digital processing board receives the signal through the acquisition channel using the ADC module, performs preprocessing such filtering and amplification to enhance signal detection strength, then samples and analyzes the signal via ADC to obtain its frequency composition and distribution, and generates and organizes pixel data. The programmable voltage board generates a high-precision adjustable power supply voltage to provide a voltage source for the device, and sets an independent bias voltage for each column of sensors to improve the anti-interference capability and linearity of sensor signal transmission. Simultaneously, it precisely adjusts the bias power supply for each column of pixels to improve pixel accuracy.

[0027] More, such as Figure 2 As shown, the front-end signal board has 16 signal source modules, each with 16 sensor units. These 16 sensor units share a bias voltage in a single bias circuit. Each sensor unit is equipped with at least one AC voltage source (AC) and an output resistor (RS1). The bias circuit includes at least one DC power supply (DC), a filter capacitor (C1), and a DC blocking capacitor (C2). The acquisition channel circuit includes at least one second load resistor (RS3).

[0028] This signal acquisition and processing device mainly consists of three parts: a front-end signal board, a digital processing board, and a programmable voltage board. The front-end signal board is used for installing the sensor probe and initializing the bias voltage. The digital processing board uses 256 channels to amplify and acquire weak signals and extract pixel parameters. The programmable voltage board is mainly used to implement a high-precision adjustable voltage source. The sensor unit is used to install the sensor array, detect and provide spatial information of terahertz waves, and probe terahertz waves. During operation, the front-end signal board preprocesses the weak signal output from the terahertz array sensor by adjusting the bias voltage, and then transmits the signal to the 256 channels of the digital processing board for further analog-to-digital conversion, gain amplification, and parameter detection. After digitizing the signal, the digital signal is rearranged to construct a two-dimensional or three-dimensional terahertz array image. The image is then enhanced, denoised, and smoothed. The programmable voltage board fine-tunes the bias voltage of each column of pixels to improve image accuracy. This allows for the acquisition of higher-precision and better-quality terahertz array imaging under more stable sensor signal strength.

[0029] In this embodiment, as Figure 3As shown in the connection diagram, the front-end signal board has 16 signal source modules, each with 16 sensor units, resulting in 256 sensor units on the front-end signal board. Since the sensor signals are very weak, small-package resistors RS2~RS2N can be used to transmit the bias voltage, resulting in a bias voltage V = VDC*RS1 / (RS1+RS2) for the sensor. Therefore, sensor bias can be achieved by controlling VDC. Furthermore, if a sensor fails (e.g., sensor 1 fails and short-circuits to ground), the current in the first bias resistor RS2 will increase slightly, but unlike an inductor, it will not pull VDC low to ground. VDC can still provide normal bias voltage for other sensors. Because existing bias inductors are too large (a 1mH inductor can be over 20mm*20mm*20mm), integrating 256 channels would result in a very large device, expensive and impossible to miniaturize. Because this embodiment replaces the commonly used bias voltage inductor in the prior art with the first bias resistor RS2, it allows for the installation of 256 channels of sensors within a size range of 100mm*100mm*20mm. If a bias inductor scheme were used, the size would exceed 5120mm*5120mm*20mm. Therefore, this embodiment demonstrates a significant advantage in achieving small-size integration of the device. Furthermore, designing multiple sensor units effectively avoids the problem in the prior art where damage to a single sensor unit affects the operation of the entire group of sensor units when using a bias inductor scheme. It should be noted that small-package inductors cannot be selected when integrating sensor units in a small size. This is because a relatively large inductor impedance is required to achieve sufficient noise isolation. As shown in the inductor impedance calculation formula, XL=jwL. When the signal frequency w is low, L needs to be very large. The size of the inductor and the inductance L are positively correlated.

[0030] During the operation of this data acquisition and processing device, the programmable voltage board is used not only for precise adjustment of the bias voltage of the pixels, but also to provide a stable voltage source for the front-end signal board and the digital processing board. The programmable voltage board provides the required bias voltage to the front-end signal board, which transmits the analog signal output from the sensor to the digital processing board. The digital processing board and the programmable voltage board are connected via a bidirectional digital I / O interface. After proper biasing, the sensor on the front-end signal board can effectively detect reflected terahertz signals and convert them into a weak voltage signal at the microvolt level. Therefore, in practical applications, the front-end signal board has two sets of signals: one set connected to the voltage board for inputting the probe bias voltage, and the other set connected to the digital processing board for outputting the weak voltage signal. The bias voltage output by the programmable voltage board needs to be precisely adjustable through user control; therefore, the front-end signal board has a set of digital interface signals connected to the processing board. Both the digital processing board and the programmable voltage board have power input interfaces for supplying power to the circuit.

[0031] The front-end signal board is used to install the sensor probe and initialize the bias voltage. After proper biasing, the sensor can effectively detect reflected terahertz signals and convert them into weak voltage signals in the microvolt range. In specific operation, the DC power supply DC, filter capacitor C1, and first load resistor RS2 constitute the bias circuit; the output resistor RS1 and AC voltage source AC constitute the sensor unit; and the second load resistor RS3 constitutes the circuit on the acquisition channel. The voltage load of the AC voltage source AC and the output resistor is borne by the second load resistor RS3, while the first load resistor RS2 and DC power supply DC provide the DC bias voltage for the sensor unit. Since the sensor probe is discrete, its voltage needs to be precisely adjusted in practical applications. As a feasible implementation method, a dedicated grounding layer can be laid on the front-end signal board to form a stripline transmission structure. The stripline transmission structure can effectively resist external noise interference and is suitable for weak signal transmission.

[0032] In this embodiment, the front-end signal board performs two functions: providing bias voltage to the sensor unit and transmitting the AC signal generated by the sensor unit to the digital processing board, which then transmits it to the analog-to-digital converter module via the acquisition channel. When the front-end signal board provides bias voltage to the probe, it provides a DC voltage VDC. VDC forms a voltage divider relationship with the probe's internal resistance RS1 via RS2. Therefore, the voltage on the probe is: VB = VDC * RS1 / (RS1 + RS2). Since RS1 and RS2 are fixed values, the probe bias voltage can be adjusted by adjusting RS1 and RS2. The front-end signal board transmits the signal to the ADC. The VAC signal generated by the probe is shunted by RS1 and RS2 and the DC blocking capacitor C2 before being transmitted. Since the DC blocking capacitor C2 is equivalent to a short circuit for AC signals, the parallel resistance of RS2 and the internal resistance R_load of the ADC is the external resistance seen by the sensor. Let Rm be the parallel resistance of RS2 and R_load, and its calculation formula is: Rm=(RS2*R_load) / (RS2+R_load). For the internal resistance of the sensor unit probe and the external resistance Rm it sees, the voltage transmitted to the outside can be calculated using the voltage divider formula, that is: V_load=VAC*Rm / (RS1+Rm). From the above formula, the voltage value transmitted by the sensor unit probe to the ADC can be obtained.

[0033] Furthermore, such as Figure 4 As shown, the digital processing board includes a first main controller, on which a signal transceiver, a first connector, a power connector, an analog-to-digital converter module, a first memory, and a second memory are connected via signal connections; a power module is connected via signal connections to the power connector; a USL connector is connected via signal connections to the acquisition channel; and a second connector is also connected via signal connections to the signal transceiver; the first connector is a QSFP connector, and the second connector is an RJ45 connector.

[0034] The USL connector is a high-frequency signal connector capable of transmitting high-frequency signals. Its structural features enable it to adapt to high-frequency signal transmission, exhibiting low impedance, low loss, and high stability. Simultaneously, the USL connector effectively prevents electromagnetic interference, providing excellent shielding for sensor output signals in the acquisition channel. Furthermore, its extremely fine structure reduces signal loss during transmission, and its structural characteristics ensure good electrical continuity, thereby guaranteeing stable signal transmission. The analog-to-digital converter (ADC) module provides at least 46dB adjustable gain amplification and an 80MSPS sampling rate. The first memory is primarily used for temporary data storage and buffering. When the signal is converted to a digital signal by the ADC module, the first memory can be used to store and process the digital signal. While the first memory is used for temporary storage or processing of signal data, the second memory can provide long-term storage of the signal data.

[0035] More specifically, the QSFP connector is an optical connector that uses optical fiber as the transmission medium, enabling high-speed signal transmission. Compared to traditional electrical signal transmission methods, optical connectors offer higher transmission speeds and lower signal loss, meeting the demands of high-speed data transmission. Secondly, optical fiber, as a transmission medium, possesses strong anti-interference capabilities; optical signals transmitted through optical fibers are less susceptible to external electromagnetic interference, ensuring signal quality and stability. Furthermore, the QSFP connector is a highly integrated connector capable of simultaneously transmitting signals from multiple channels. Compared to traditional connectors, the QSFP connector has a higher degree of integration, improving system stability and reliability while reducing system complexity and cost, thus meeting the high integration requirements of the signal acquisition and processing device in this embodiment.

[0036] Furthermore, such as Figure 5 As shown, the analog-to-digital conversion module internally includes a main signal link. This main signal link comprises a signal attenuator, a low-noise amplifier, a filter, a first analog-to-digital converter, and a digital processing unit, connected sequentially. The input terminal of the signal attenuator receives the signal, and the output terminal of the digital processing unit outputs the signal. In this specific application, the signal attenuator has two input terminals, INP and INM, for positive and negative voltage inputs respectively. Furthermore, the signal transmission from the signal attenuator to the digital processing unit outputs the signal in a dual-ended output manner based on both positive and negative voltages.

[0037] The purpose of setting up a current output channel is to treat the output current as a type of digital signal during analog-to-digital conversion, which can be used to represent the amplitude or intensity of the analog signal. Converting analog signals to digital signals allows for better signal processing and transmission, while also improving signal stability and reliability. In the analog-to-digital conversion module, the magnitude of the output current is typically related to the amplitude of the analog input signal, exhibiting a certain linear relationship. The amplitude of the output current can be amplified or reduced to facilitate subsequent signal processing or transmission. Furthermore, the output current can also be converted to digital signals or other signal types for use in different application scenarios. The clock signal module provides the operating clock signal, and the phase generator generates ordered digital signals that represent the phase information of the analog signal. The digital signal output by the phase generator can be used to control the output current process of the A / D converter, thereby achieving precise control and regulation of the output current. The ring oscillator provides feedback to the output current process, changing the waveform of the output current to make it smoother and more stable. Its role in the output current process is to generate a positive feedback signal to change the waveform of the output current, making it smoother and more stable. Its effect is to improve the quality of the output current while reducing output noise.

[0038] In the analog-to-digital converter (ADC) module, the signal attenuator is used to attenuate the input signal to a range suitable for the LNA low-noise amplifier when the input signal is large. The low-noise amplifier is used to amplify the signal to a range suitable for the ADC to acquire when the input signal is weak. The filter is used to filter out high-frequency noise transmitted from the signal link, preventing the ADC from acquiring other Nyquist domain signals that fold back into the first Nyquist domain, interfering with the main signal. The ADC is used to perform analog-to-digital signal conversion because the data processed in the FPGA main controller and PC can only be in digital form, so conversion is required here. The digital processing unit is used to preprocess the data extraction, reducing the sampling rate to facilitate subsequent FPGA program design. The weak signal output from the sensor is simultaneously input from both INP and INM ports and enters the signal attenuator. The signal attenuator attenuates the input signal according to a pre-set certain ratio, thus transforming it into a signal suitable for the first ADC. The signal after filtering is converted and amplified by the first ADC and the DSP amplification module before being transmitted to the programmable voltage board. As a feasible implementation method, in specific applications, preferably, an SPI serial peripheral interface is set inside the analog-to-digital converter module for configuration management of each module in the signal link; a reference voltage unit is also set on the analog-to-digital converter for reference in the quantization of the analog-to-digital converter, because the ADC can only compare the input analog signal with the reference voltage to obtain the percentage of the input voltage to the reference voltage, and then give the percentage of the full code value as the quantization result.

[0039] Furthermore, such as Figure 6 As shown, the programmable voltage board includes a second main controller, a DC-DC converter, a low-voltage regulator, a current sensor, and a third connector, wherein the DC-DC converter, the low-voltage regulator, the current sensor, and the third connector are sequentially connected by signals; the second main controller is equipped with a first digital-to-analog converter, a second analog-to-digital converter, a serial port module, and a digital I / O interface module, and the output terminal of the second main controller for switch control and the output terminal of the first digital-to-analog converter for voltage control are both connected to the input terminal of the low-voltage regulator; the output terminal of the low-voltage regulator to the current sensor has a second branch for voltage acquisition, and the second branch is connected to the input terminal of the second analog-to-digital converter; the output terminal of the current sensor for current acquisition is connected to the input terminal of the second analog-to-digital converter.

[0040] On one hand, the first digital-to-analog converter (DAC), the low-voltage regulator, and the second analog-to-digital converter (ADC) sequentially form a voltage control and voltage acquisition link, which enables the mutual conversion between digital and analog signals. When a digital signal is input, the DAC converts it into an analog signal, then the low-voltage regulator stabilizes the voltage, and finally the ADC converts it back into a digital signal. This connection method enables the mutual conversion between digital and analog signals while also stabilizing the voltage of the analog signal. Simultaneously, a current sensor acquires current from the second ADC. On the other hand, the key link lies in the system consisting of the DC-DC converter, the low-voltage regulator, the current sensor, and the third connector. The DC-DC converter converts the bus power input to the board into the primary power supply of the low-voltage regulator. Since each device has only one power input interface and needs to convert from bus power to a lower voltage, a DC-DC converter is required. Its advantages include high efficiency and small size. The low-voltage output power supply of the DC-DC converter contains a significant amount of noise. Therefore, a low-voltage regulator is used to suppress this noise, ensuring that only clean, noise-free DC power is transmitted (the sensor probe generates a weak signal, requiring low noise; therefore, a noise-free DC bias power supply is used). The low-voltage regulator also has two control interfaces: a VFB control interface and an EN channel enable interface. The VFB interface is used for fine-tuning the output voltage, enabling microvolt-level voltage correction. EN controls whether power is supplied to the front-end signal board. The current sensor uses a sampling resistor, which converts current into voltage using Ohm's law. Therefore, an ADC can be used to detect this voltage, and dividing the voltage by the sampling resistor value yields the current for that channel. Additionally, the voltage acquisition before the current sensor monitors the port voltage to determine if the front-end signal board is functioning correctly. The third connector is used to transmit the voltage signal generated by the voltage board to the front-end signal board.

[0041] It should be noted that the DC-DC converter is used for primary power conversion, while the low-voltage regulator is used to attenuate the output noise of the DC-DC converter, stabilize the output voltage, and protect the equipment. Due to fluctuations in the power supply voltage or changes in the load, the output voltage of the DC-DC converter may vary, but the low-voltage regulator can stabilize it at a predetermined voltage value. A low-noise power supply is then output. A current sensor is used to monitor the output current in the circuit, thereby ensuring circuit safety. Connecting the low-voltage regulator output to the current sensor limits its output current within a safe range, thus protecting the circuit. The third connector is used to transmit voltage to the front-end signal board.

[0042] As a feasible implementation method, in practical applications, the signal transmitted between the front-end signal board and the digital processing board is weak and easily interfered with by noise, reducing the detection resolution of the device. To solve this problem, the solution selects coaxial connectors and coaxial cables as the signal transmission solution. Due to the high channel density of this device, the size and cost of conventional coaxial cables are not feasible. Therefore, the solution selects miniature coaxial cables as the signal transmission channel. Each signal cable has an external shielding layer with a spacing of 0.4mm, which can achieve a high degree of integration and noise shielding.

[0043] Furthermore, such as Figure 7 As shown, a voltage regulator RT, a conversion resistor RDAC, and a grounding resistor RB are provided between the low-voltage regulator and the first digital-to-analog converter. The low-voltage regulator has a first voltage terminal V0 and a feedback voltage terminal. The first digital-to-analog converter has a second voltage terminal V0-DAC. The V0 terminal is connected to one end of the voltage regulator RT, and the V0-DAC terminal is connected to one end of the conversion resistor RDAC. The grounding terminal of the grounding resistor RB is grounded. The other end of the voltage regulator RT, the other end of the conversion resistor RDAC, the enable terminal of the grounding resistor RB, and the feedback voltage terminal are connected to the same point. The currents of the V0 terminal, the V0-DAC terminal, the feedback voltage terminal, and the grounding resistor RB are respectively set as the first current I_RT, the second current I_DAC, the third current I_FB, and the fourth current I_RB.

[0044] The programmable voltage regulator is useful because the output power supply voltage can be precisely adjusted with an accuracy of 100μV, and is user-controlled. The output voltage V0 of the low-voltage regulator is proportional to the feedback voltage V_FB; therefore, the output voltage V0 can be controlled by precisely controlling the voltage of V_FB. According to Kirchhoff's current law:

[0045] I_FB+I_RT+I_RB+I_DAC=0.

[0046] Since the feedback voltage input current I_FB of the low-voltage regulator is 0, the I_RT current is (V_FB-V0) / RT, the I_RB current is V_FB / RB, and the I_DAC current is (V_FB-V0_DAC) / RDAC, the output voltage of the low-voltage regulator can be expressed by the following formula:

[0047] V0=-(R_T) / (R_DAC)*V0_DAC+(R_T / R_DAC+R_T / R_B+1)*V_FB.

[0048] As can be seen from the above formula, the output voltage V0 of the low-voltage regulator can be adjusted by adjusting the DAC output voltage V0_DAC. The adjustment accuracy of the output voltage of the first digital-to-analog converter is very high, so the adjustment accuracy of the output voltage of the low-voltage regulator can also reach a very high level.

[0049] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A 256-channel weak signal acquisition and processing device, characterized in that, The device comprises a front-end signal board, a digital processing board and a programmable voltage board; The front-end signal board is used for completing installation of the terahertz sensor and adding voltage bias, providing bias voltage for the terahertz sensor and generating a terahertz signal required by the device, and transmitting the signal to the digital processing board; the front-end signal board is provided with a plurality of signal source modules, each signal source module comprises a bias circuit and a plurality of sensor units, and the plurality of sensor units in each signal source module share bias voltage in the bias circuit; a first load resistor RS2 is arranged on each sensor unit for bias voltage transmission; The digital processing board is provided with an analog-to-digital conversion module, and the analog-to-digital conversion module is provided with an acquisition channel; the digital processing board is used for receiving signals through the acquisition channel by using the analog-to-digital conversion module, pre-processing the signals by filtering and amplifying to enhance the detection strength of the signals, sampling and processing the signals by analog-to-digital conversion, and analyzing the signals to obtain the frequency composition and distribution of the signals, and generating and arranging pixel data of the signals; The programmable voltage board is used for generating high-precision adjustable power supply voltage to provide voltage source for the device, and independently setting independent bias voltage for each column of sensor units to improve the anti-interference ability and linearity of sensor signal transmission, and accurately adjusting the bias power supply for each column of pixel points to improve the pixel point precision.

2. The 256-channel weak signal acquisition and processing device according to claim 1, characterized in that, The front-end signal board is provided with 16 signal source modules, each signal source module is provided with 16 sensor units, and the 16 sensor units share bias voltage in one bias circuit.

3. The 256-channel weak signal acquisition and processing device according to claim 1, characterized in that, At least one alternating voltage source AC and one output resistor RS1 are arranged on the sensor unit; the bias circuit is provided with at least one direct current source DC, one filter capacitor C1 and one direct current blocking capacitor C2; and at least one second load resistor RS3 is arranged on the circuit of the acquisition channel.

4. The 256-channel weak signal acquisition and processing device according to claim 1, characterized in that, The digital processing board comprises a first main controller, and the first main controller is provided with a signal transceiver, a first connector, a power connector, an analog-to-digital conversion module, a first memory and a second memory in signal connection; the power connector is provided with a power module in signal connection; the acquisition channel is provided with a USL connector in signal connection; the signal transceiver is further provided with a second connector in signal connection; the first connector is a QSFP connector, and the second connector is an RJ45 connector.

5. The 256-channel weak signal acquisition and processing device according to claim 4, characterized in that, The analog-to-digital conversion module is internally provided with a main signal link, and the main signal link comprises a signal attenuator, a low-noise amplifier, a filter, a first analog-to-digital converter and a digital processing unit connected in sequence; the input end of the signal attenuator is used for receiving signals, and the output end of the digital processing unit outputs signals.

6. The 256-channel weak signal acquisition and processing device according to claim 1, characterized in that, The programmable voltage board comprises a second main controller, a direct current converter, a low-voltage stabilizer, a current sensor and a third connector, wherein the direct current converter, the low-voltage stabilizer, the current sensor and the third connector are sequentially signal connected; the second main controller is provided with a first digital-to-analog converter, a second analog-to-digital converter, a serial port module and a digital IO interface module which are signal connected, and the output end of the second main controller for switch control and the output end of the first digital-to-analog converter for voltage control are both connected to the input end of the low-voltage stabilizer; the output end of the low-voltage stabilizer output to the current sensor is provided with a second branch for voltage collection, and the second branch is connected to the input end of the second analog-to-digital converter; the output end of the current sensor for current collection is connected to the input end of the second analog-to-digital converter.

7. The 256-channel weak signal acquisition and processing device according to claim 6, characterized in that, The low-voltage stabilizer and the first digital-to-analog converter are further provided with a stabilizing resistor RT, a conversion resistor RDAC and a grounding resistor RB; the low-voltage stabilizer is provided with a first voltage end V0 end and a feedback voltage end, and the first digital-to-analog converter is provided with a second voltage end V0-DAC end; one end of the stabilizing resistor RT is connected to the V0 end, one end of the conversion resistor RDAC is connected to the V0-DAC end, the grounding end of the grounding resistor RB is grounded, and the other end of the stabilizing resistor RT, the other end of the conversion resistor RDAC, the enable end of the grounding resistor RB and the feedback voltage end are connected to the same point; the V0 end, the V0-DAC end, the feedback voltage end and the branch current of the grounding resistor RB are respectively set as a first current I_RT, a second current I_DAC, a third current I_FB and a fourth current I_RB.

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