Electronic terminal transfer function test system and method based on analog-to-digital conversion

Abstract

The invention discloses an electronic terminal transfer function test system and method based on analog-to-digital conversion. Relates to the technical field of electrical testing and automatic control, in particular to an electronic terminal transfer function testing system and method based on analog-to-digital conversion. Input and output signals of a controlled object are synchronously acquired and processed, and high-precision extraction of amplitude and phase is realized by combining sine frequency sweep excitation with parameter fitting calculation, so that frequency response characteristics of a system in a target frequency band are obtained. The system comprises a main control board, an upper computer and a controlled object, one end of the main control board is connected with the upper computer, and the other end is connected with a controlled object; the upper computer is used for generating a test instruction and sending the test instruction to the main control board; the main control board is used for synchronously acquiring a test excitation signal output by the main control board and a response signal output by a controlled object; and the controlled object receives the test excitation signal output by the main control board and outputs a response signal. And the upper computer generates frequency response characteristics according to the synchronously acquired signals.

Description

An electronic terminal transmission function testing system and method based on analog-to-digital conversion Technical Field

[0001] This invention relates to the field of electrical testing and automatic control technology, specifically to an electronic terminal transmission function testing system and method based on analog-to-digital conversion. Background Technology

[0002] In automatic control and servo system engineering applications, to achieve stable control and performance optimization of the controlled object, it is usually necessary to first analyze the controlled object, clarify its dynamic characteristics and input-output relationship, and establish a corresponding mathematical model based on this. However, in actual engineering scenarios, the controlled object, such as a fast-reflecting mirror or a turntable, often includes multiple sub-components such as motors, drivers, power amplification stages, mechanical structures, sensors, and filtering stages, and is subject to factors such as parameter uncertainty, nonlinearity, time-varying characteristics, and external disturbances, making it difficult to obtain an accurate model solely through theoretical derivation.

[0003] To obtain the frequency response characteristics of a controlled object, early methods primarily relied on frequency response meters. These methods calculated the phase difference based on the time difference between the zero-crossing points of the input and output signals, and the amplitude based on the signal peak value. However, since actual system outputs often contain nonlinear factors, this testing method is easily affected by noise interference, making it difficult to obtain stable and reliable measurement results under normal operating conditions.

[0004] Existing testing systems typically treat signal generation, acquisition, and the tested object as independent processes, failing to effectively eliminate amplitude and phase attenuation between the signal generation point and the input of the tested object. This results in test results containing systematic errors, and a lack of comparability between test data from different batches and under different environments. Furthermore, existing frequency response testers are mostly laboratory-grade equipment, bulky, costly, and complex in wiring, making them difficult to deploy directly in engineering fields for online testing and real-time performance evaluation. These shortcomings limit the reliability of servo system controller design, parameter tuning, and performance evaluation, necessitating a frequency response testing solution that can achieve high precision, self-calibration, and portable deployment in complex engineering environments. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to propose an electronic terminal transfer function testing system and method based on analog-to-digital conversion. The system synchronously acquires and processes the input and output signals of the controlled object, and utilizes sinusoidal frequency sweep excitation combined with parameter fitting calculations to achieve high-precision extraction of amplitude and phase, thereby obtaining the system's frequency response characteristics within the target frequency band.

[0006] The system includes: a main control board, a host computer, and a controlled object; one end of the main control board is connected to the host computer, and the other end is connected to the controlled object; the main control board includes at least one digital-to-analog conversion channel for outputting test excitation signals; the main control board includes at least two analog-to-digital conversion channels for synchronously acquiring the test excitation signals output by the main control board and the response signals output by the controlled object; for sending the synchronously acquired signals to the host computer; the host computer is used to generate test commands and send the test commands to the main control board; for receiving the synchronously acquired signals from the main control board and generating frequency response characteristics based on the synchronously acquired signals; the controlled object receives the test excitation signals output by the main control board and outputs response signals.

[0007] Furthermore, the two analog-to-digital conversion channels are synchronously acquired under the same sampling clock; the test excitation signal is a sinusoidal sweep frequency signal; each digital-to-analog conversion channel includes at least one DA module; each analog-to-digital conversion channel includes at least one AD module.

[0008] A method for testing the transmission function of an electronic terminal based on analog-to-digital conversion (ADC), the method being implemented based on the aforementioned system, includes the following steps: S1, the host computer sets a frequency table and generates and transmits test instructions to the main control board, the test instructions including at least a sweep frequency range and an excitation amplitude; S2, the ADC channel of the main control board outputs a test excitation signal according to the test instructions; the test excitation signal is divided into two paths, one input to the controlled object and the other input to the first ADC channel of the main control board; S3, after receiving the test excitation signal, the controlled object outputs a response signal to the second ADC channel of the main control board; S4, the main control board uses the test excitation signal collected by the first ADC channel and the response signal collected by the second ADC channel as sampling signals, and transmits them, along with the frequency index value of the sampling signals, to the host computer; S5, the host computer performs steady-state filtering on the sampling signals and performs parameterization processing on the filtered sampling signals to obtain the amplitude of the steady-state response signal. and phase S6. The host computer plots the amplitude-frequency response curve and the phase-frequency response curve based on the amplitude and phase parameters of the steady-state response signal.

[0009] Furthermore, the parameterization process includes: S51, looking up the frequency table based on the frequency index value of the sampled signal to obtain the current theoretical frequency value; S52, deducing the steady-state response signal voltage value based on the steady-state response signal; S53, calculating the current actual frequency value based on the steady-state response signal using a fast Fourier transform. S54. Construct a sinusoidal model and fit the steady-state response signal; S55. Based on the sinusoidal model, construct the observation matrix, and solve the observation matrix using the linear least squares method to obtain the amplitude of the steady-state response signal. With phase .

[0010] Furthermore, the formula for calculating the voltage value of the inverse steady-state response signal is: ,in, This indicates the test excitation signal received by the first analog-to-digital conversion channel. This indicates the response signal received by the second analog-to-digital conversion channel. Indicates the reference voltage of the AD module. Indicates the resolution of the AD module. Indicates circuit gain. This represents the voltage value of the input signal to the controlled object. The voltage value of the output signal of the controlled object; the actual frequency value The formula for calculation is: ,in, This represents the index of the frequency point with the largest amplitude in the steady-state response signal after processing by the Fast Fourier Transform. Indicates the sampling rate. Indicates the number of sampling points.

[0011] Furthermore, the sinusoidal model is specifically as follows: ,in, Represents the steady-state response signal angular frequency, through calculate, The time series representing the steady-state response signal. The bias represents the steady-state response signal; the observation matrix is ​​specifically: The method of solving the observation matrix using linear least squares specifically involves: constructing the coefficient matrix to be solved. ;according to , Construct an error function using the steady-state response signal voltage value: ,in, Represents the steady-state response signal voltage value, including and ;right Find the derivative and set it to zero to solve the problem. , and ;according to , and Solution , and : ; ; .

[0012] Furthermore, respectively targeting and By executing steps S53 to S55, the amplitude input by the controlled object can be obtained. Phase input of the controlled object The amplitude of the controlled object's output and the phase output by the controlled object ; , , and The amplitude of the steady-state response signal With phase .

[0013] Furthermore, the amplitude-frequency response curve is specifically as follows: The phase frequency response curve is specifically as follows: .

[0014] Furthermore, the steady-state screening specifically involves selecting the sampling signal from the second half of the total sampling period as the steady-state response signal.

[0015] The beneficial effects of the method described in this invention are as follows: (1) The main control board of the system described in this invention integrates DA output and AD input, and realizes signal generation and synchronous acquisition through a single board, which reduces the synchronization error and wiring complexity caused by the separation of signal source and acquisition device in traditional test systems.

[0016] The main control board output channel 2 is connected to both input channel 1 and the input terminal of the controlled object. Utilizing a dual-channel synchronous acquisition structure, it automatically cancels the amplitude and phase attenuation between the signal generation and the input terminal of the measured object during frequency response calculation, thus eliminating the system error introduced by the channel.

[0017] (2) The main control board of the present invention transmits digital quantities and frequency array indices instead of directly transmitting voltage and frequency values. It uses integer indices to replace floating-point number transmission, which significantly reduces the amount of serial communication data and improves the data transmission efficiency during frequency sweep test.

[0018] The host computer obtains the theoretical frequency by looking up the table based on the frequency array index, and combines the voltage value with the local parameters to distribute the calculation load on the host computer, which reduces the calculation pressure on the main control board and ensures the real-time sampling. (3) The method described in this invention uses FFT analysis to replace the theoretical set frequency with the actual signal frequency, and accurately calculates the actual value of the current frequency point by locating the peak value of the spectrum, eliminating the frequency deviation caused by factors such as signal source drift and temperature drift, and improving the matching degree between the sine model and the actual signal.

[0019] (4) The present invention takes the last half of the total sampling period as the steady-state response and returns the starting point of the time series to zero, which effectively eliminates the influence of the transient process of frequency switching, ensures that the data used for parameter identification is in the stable response stage, and reduces the truncation error.

[0020] The time series zeroing process provides a unified benchmark for phase calculations at different frequencies, ensuring the consistency and continuity of phase frequency response curves when comparing across frequency points.

[0021] (5) The present invention adopts the least squares sine fitting algorithm to transform the nonlinear phase problem into a linear coefficient solution and obtains the optimal estimate directly through matrix operation. Compared with the zero-crossing / peak detection method, it has a stronger ability to suppress harmonic distortion and nonlinear distortion.

[0022] An observation matrix containing sine, cosine, and constant terms is constructed to simultaneously estimate signal amplitude, phase, and DC bias, avoiding interference from DC components in AC parameter extraction and improving parameter estimation accuracy under complex operating conditions.

[0023] By utilizing the statistical averaging properties of linear least squares, fundamental frequency component information can be extracted from distorted waveforms. Stable amplitude and phase estimation can still be obtained under conditions of nonlinear distortion and noise interference, thus expanding the applicable conditions of the test method.

[0024] (6) The method described in this invention achieves portable and low-cost transfer function testing capabilities without adding external precision instruments through the synergistic effect of dual-channel synchronous acquisition self-calibration mechanism, FFT frequency correction, steady-state screening and least squares fitting, supporting closed-loop or open-loop online testing in engineering sites. Attached Figure Description

[0025] Figure 1 is a flowchart of the method described in this invention; Figure 2 is a schematic diagram of the test excitation signal waveform acquired by the first analog-to-digital conversion channel of this invention, with the horizontal axis representing time and the vertical axis representing voltage; Figure 3 is a schematic diagram of the response signal waveform acquired by the second analog-to-digital conversion channel of this invention, with the horizontal axis representing time and the vertical axis representing voltage; 1-main control board, 2-host computer and 3-controlled object. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This embodiment provides an electronic terminal transmission function testing system based on analog-to-digital conversion, as shown in Figure 1. The system includes: a main control board 1, a host computer 2, and a controlled object 3. In this embodiment, the controlled object 3 is a turntable. One end of the main control board 1 is connected to the host computer 2, and the other end is connected to the controlled object 3. The main control board 1 includes two digital-to-analog conversion channels (DA1 and DA2) for outputting test excitation signals. The test excitation signals are sinusoidal sweep signals. Each digital-to-analog conversion channel includes at least: one DA module, one inverting proportional operation circuit, one non-inverting proportional operation circuit, and one addition / subtraction operation circuit. The DA module has a resolution of 16 bits and can output a voltage of ±0.1V to ±10V after being amplified by one inverting proportional operation circuit, one non-inverting proportional operation circuit, and one addition / subtraction operation circuit. In this embodiment, the digital-to-analog conversion channel uses one inverting proportional operation circuit, one non-inverting proportional operation circuit, and one addition / subtraction operation circuit to output a bipolar voltage value from the unipolar DA output module.

[0028] Each analog-to-digital converter channel includes: one AD module, two inverting proportional operation circuits, and one addition / subtraction operation circuit, ensuring that the input voltage of the unipolar AD module is within the AD range.

[0029] The main control board 1 includes two analog-to-digital conversion channels (AD1 and AD2) for synchronously acquiring the test excitation signal output by the main control board 1 and the response signal output by the controlled object 3. Each analog-to-digital conversion channel includes at least one AD module, two inverting proportional operation circuits, and one addition and subtraction operation circuit. The resolution of the AD module is 16 bits. In this embodiment, the analog-to-digital conversion channel uses two inverting proportional operation circuits and one addition and subtraction circuit to ensure that the input voltage of the unipolar AD module is always within the AD voltage range.

[0030] The main control board 1 also includes a communication module (those skilled in the art can set up the communication module according to actual needs), which communicates with the host computer 2 through a serial port (USB data transmission cable).

[0031] The two analog-to-digital conversion channels are synchronously acquired under the same sampling clock; the synchronously acquired signals are sent to the host computer 2; the host computer 2 is used to generate test commands and send the test commands to the main control board 1; it is used to receive the synchronously acquired signals from the main control board 1 and generate frequency response characteristics based on the synchronously acquired signals; the frequency response characteristics include: amplitude frequency response curve and phase frequency response curve.

[0032] The controlled object 3 receives the test excitation signal output by the main control board 1 and outputs a response signal.

[0033] The system also includes a drive board, which is connected to the main control board 1, the controlled object (fast-reflecting mirror) 3 and the DC power supply respectively, and is used to provide 24V voltage to the main control board 1 and the fast-reflecting mirror 3 through the DC power supply.

[0034] Example 2: This example is a further limitation of Example 1. This example provides a method for testing the transmission function of an electronic terminal based on analog-to-digital conversion. The method is implemented based on the system described in Example 1.

[0035] The method includes the following steps: S1, the host computer 2 sets the frequency table and generates and transmits test instructions to the main control board 1. The test instructions include: sine sweep frequency signal parameters, amplitude, number of cycles, sweep start frequency, sweep end frequency and frequency array step value. The sweep frequency will be updated point by point according to the step value.

[0036] In this embodiment, the sweep frequency dynamic range is 1Hz-1kHz, and the frequency table includes the sampling frequency index value and the corresponding sampling frequency.

[0037] S2. The analog-to-digital converter channel (DA2) of the main control board 1 outputs the corresponding voltage according to the test command and the digital quantity corresponding to the standard sinusoidal voltage change: the test excitation signal; the test excitation signal is divided into two paths, one path is input to the controlled object 3, and the other path is input to the first analog-to-digital converter channel (AD1) of the main control board 1 as the input of the controlled object 3; S3. After receiving the test excitation signal, the controlled object 3 outputs a response signal to the second analog-to-digital converter channel (AD2) of the main control board 1; S4. The main control board 1 uses the test excitation signal collected by the first analog-to-digital converter channel and the response signal collected by the second analog-to-digital converter channel as sampling signals, and transmits them together with the frequency index value of the sampling signals (the frequency index value of the sampling signals corresponds to the sampling frequency index value in the frequency table) to the host computer 2; the waveform of the test excitation signal collected by the first analog-to-digital converter channel, as shown in Figure 2, is a standard sine wave.

[0038] The response signal waveform acquired by the second analog-to-digital conversion channel is shown in Figure 3. Because the output of the controlled object 3 contains nonlinear factors (including noise), the output waveform is distorted. Traditional zero-crossing detection and peak detection methods assume the output is a standard sine wave, calculating the phase difference by detecting the time difference between the zero-crossing points and the amplitude by detecting the peak value. When the output waveform is distorted, the zero-crossing position deviates from the true zero-crossing point of the fundamental frequency component, and the peak point may correspond to the extreme value of the harmonic component rather than the fundamental frequency amplitude. This results in significant errors, or even complete distortion, in the calculated amplitude ratio and phase difference.

[0039] Steps S1-S4 are executed by the main control board 1, and steps S5 onwards are executed by the host computer 2.

[0040] S5, the host computer 2 performs steady-state filtering on the sampled signals at each frequency point, and then performs parameterization processing on the filtered sampled signals to obtain the amplitude of the steady-state response signal. and phase After the host computer 2 receives and parses the data for each frequency point, to avoid transient responses caused by frequency switching, it needs to wait for the system to enter a steady state before performing frequency response analysis. Therefore, this embodiment performs steady-state screening on the sampled signals of each frequency point. Specifically, for fast-reflection mirrors or turntable-type servo systems, this embodiment selects the sampled signal of the last half of the total sampling period as the steady-state response signal. To ensure the comparability of different sampled signals in phase calculation, the selected steady-state response time period is normalized to align the starting points of the time series, i.e., the time series starts from 0, and phase analysis is performed on the same scale.

[0041] The total sampling period is calculated based on the frequency value of the current frequency point and the number of periods set. Specifically, the total number of data points in the sampling period is calculated as follows: (sampling rate of the current frequency point * number of periods set by the host computer 2) / frequency value of the current frequency point. In this embodiment, the last half of the number of periods set by the host computer 2 is selected. For example, if the number of periods set by the host computer 2 is 10, then the last 5 periods are selected for each frequency point.

[0042] The parameterization process includes: S51, based on the frequency index value of the sampled signal, looking up the frequency table to obtain the current theoretical frequency value as the initial estimate for subsequent FFT frequency analysis; if the frequency value and voltage value are directly transmitted, floating-point numbers or values ​​with multiple significant digits need to be transmitted, resulting in a large data volume; while the frequency array index is of integer type and has a limited value range, usually only requiring one byte to represent. The host computer 2 locally stores the frequency table corresponding to the index. After receiving the index, the frequency value can be restored by looking up the table, without the need for the main control board 1 to transmit complete frequency information. Similarly, transmitting AD digital values ​​instead of converted voltage values ​​avoids the transmission of floating-point numbers, and the host computer 2 uses known parameter formulas to locally inversely solve the voltage. This embodiment significantly reduces the amount of data transmitted in a single transmission while ensuring information integrity, and improves communication efficiency, especially suitable for high-frequency, continuous data transmission scenarios during frequency sweep testing.

[0043] S52. Determine the steady-state response signal voltage value based on the steady-state response signal; the formula for calculating the steady-state response signal voltage value is: ,in, This indicates the test excitation signal received by the first analog-to-digital conversion channel. This indicates the response signal received by the second analog-to-digital conversion channel. Indicates the reference voltage of the AD module. Indicates the resolution of the AD module. Indicates circuit gain. This represents the voltage value of the input signal to the controlled object 3. This represents the voltage value of the output signal of the controlled object 3. In this embodiment, the method for obtaining the circuit gain (Gain) is as follows: During the system design phase, based on the matching relationship between the input voltage range of the selected AD module and the actual voltage range of the measured signal, the corresponding gain coefficient is determined through the amplification or attenuation network in the signal conditioning circuit. This gain coefficient is determined by the resistance ratio or amplifier configuration of the hardware circuit. During the system calibration process, a known standard voltage signal is input, the corresponding AD output digital quantity is measured, and the actual gain value is calculated according to the inverse formula. This value is stored in the host computer 2 or the main control board 1 for subsequent voltage value inverse calculation.

[0044] The above parameters are known based on the module and circuit characteristics. The current signal frequency array index, input, and output digital values ​​are transmitted to the host computer.

[0045] S53. Based on the steady-state response signal, calculate the current actual frequency value using the Fast Fourier Transform. Specifically, during the frequency sweep process, due to factors such as signal source accuracy and temperature drift, the actual output frequency may deviate from the theoretical set value. To improve the fitting accuracy, a Fast Fourier Transform (FFT) is performed on the steady-state response signal, the amplitude spectrum is taken, and after removing the DC component, the frequency index with the largest amplitude is found. , According to the formula Calculate the current actual frequency value ,in The sampling rate is 10kHz in this embodiment. The number of sampling points (in this embodiment, it is dynamically calculated based on the number of cycles and the current frequency) The calculated actual frequency The replacement of theoretical frequency values ​​for subsequent sinusoidal model construction can effectively eliminate fitting errors caused by frequency deviations.

[0046] Therefore, it can be further concluded that when the number of cycles or the total number of data points of a sinusoidal signal is known in advance, this method can be used to solve for the signal frequency when the signal frequency is unknown.

[0047] This is how it was calculated. It is the actual frequency of the signal, which is more accurate than the theoretical setting.

[0048] S54. Construct a sinusoidal model and fit the steady-state response signal; select appropriate model parameters according to the signal type. Since the test signal is a sine wave, construct the following equation:

[0049] To make writing easier, , The sinusoidal model can be simplified as follows: ,in, This represents the angular frequency of the steady-state response signal. , The time series representing the steady-state response signal. , This represents the bias of the steady-state response signal; since the input and output calculation formulas are the same, they will not be distinguished below.

[0050] S55. Based on the aforementioned sinusoidal model, construct the observation matrix, and solve the observation matrix using the linear least squares method to obtain the amplitude of the steady-state response signal. With phase The sinusoidal model obtained in step S54 is subjected to a linear transformation to obtain: The observation matrix is ​​specifically as follows: Let the coefficient matrix to be solved be... The sinusoidal model can be expressed as: Furthermore, it can also be expressed as: .

[0051] make

[0052] in, This represents an N-row, 1-column matrix.

[0053] To minimize the fitting error and make the frequency response closest to the real system, the least squares approach is used to minimize the sum of squared errors, based on... , Construct an error function using the steady-state response signal voltage value: ,in, Represents the steady-state response signal voltage value, including and Expanding the above formula yields... To make the error function To reach the minimum, Find the derivative and set it to zero to solve the problem. , and The solution process is as follows: ,

[0054] make = 0, therefore we can get ;according to , and Solution , and : ; ; .

[0055] Specifically for and By executing steps S53 to S55, the amplitude input by the controlled object 3 can be obtained. Phase input of controlled object 3 The amplitude output by the controlled object 3 and the phase output of controlled object 3 ; , , and The amplitude of the steady-state response signal With phase .

[0056] S6. The host computer 2 plots the amplitude-frequency response curve and the phase-frequency response curve based on the amplitude and phase parameters of the steady-state response signal.

[0057] The amplitude-frequency response curve is specifically as follows: The phase frequency response curve is specifically as follows: .

[0058] Thus, after the excitation input, the controlled object 3 outputs, the main control board 1 collects, and the host computer 2 identifies the signal parameters, the frequency response characteristics of the controlled object 3, i.e., the Bode plot, can be obtained. Experimental results show that this method of obtaining the transfer function has high reliability in a noisy environment.

[0059] Example 2 is a further limitation of Example 1. This example simulates a frequency response measurement scenario under noisy conditions. This example uses an "offline noise injection" method: while keeping the original sweep input amplitude and frequency settings unchanged, zero-mean Gaussian white noise is superimposed on the acquired input / output discrete sequences to construct test datasets under different signal-to-noise ratio (SNR) conditions. The SNR formula in this example is as follows:

[0060] Indicates signal power. The noise power is represented by a sweep excitation amplitude of 1 V, a frequency range of 1 Hz to 1000 Hz, and 10 complete cycles are collected at each frequency point, with a sampling rate of 10 kHz. The signal-to-noise ratio of each group of data is adjusted to be (30 dB, 10 dB) by adjusting the noise standard deviation. The same random number sequence is generated to ensure that the two methods are compared at the same noise level and to avoid random factors.

[0061] Using the method described in this invention and the zero-crossing detection method on the same dataset, the amplitude ratio and phase difference were estimated at 45dB (initial signal-to-noise ratio of normal environment), 30dB (noise is Gaussian white noise) and 10dB (noise is Gaussian white noise), and compared with the theoretical values. The amplitude error and phase error were statistically analyzed. The statistical results are shown in Tables 1, 2 and 3, respectively.

[0062] The formulas for calculating the input and output amplitudes of the zero-crossing detection method are as follows:

[0063]

[0064] in, and These represent the maximum and minimum voltage values ​​of the input signal, respectively. and These represent the maximum and minimum voltage values ​​of the output signal, respectively; comparing them yields the amplitude ratio:

[0065] The phase difference is calculated as follows:

[0066] The time difference between the zero-crossing points of the rising edges of the two waveforms. This indicates the frequency of the test signal in this embodiment.

[0067] Table 1

[0068] Table 2

[0069] Table 3

[0070] The above statistical results show that the method described in this invention has high reliability in noisy environments.

[0071] For example, as shown in Table 3, when SNR=10 dB, the zero-crossing detection method exhibits significant deviations at several frequency points: its amplitude ratio deviates due to noise superposition; taking 1 Hz as an example, the estimated deviation from the theoretical value is approximately 5 dB. Phase also shows error accumulation caused by zero-crossing jitter; taking 380 Hz as an example, the estimated deviation from the theoretical value is approximately 30°. In contrast, the method described in this invention, under the same conditions, controls deviations from the theoretical value to within 0.3 dB and 2°. Combining Tables 1 to 3, it can be concluded that under general operating conditions, the method described in this invention has better engineering applicability and reliability.

Claims

1. An electronic terminal transmission function testing system based on analog-to-digital conversion, characterized in that, The system includes: a main control board (1), a host computer (2), and a controlled object (3); one end of the main control board (1) is connected to the host computer (2), and the other end is connected to the controlled object (3); the main control board (1) includes at least one digital-to-analog conversion channel for outputting test excitation signals; the main control board (1) includes at least two analog-to-digital conversion channels for synchronously acquiring the test excitation signals output by the main control board (1) and the response signals output by the controlled object (3); for sending the synchronously acquired signals to the host computer (2); the host computer (2) is used to generate test instructions and send the test instructions to the main control board (1); for receiving the synchronously acquired signals from the main control board (1) and generating frequency response characteristics based on the synchronously acquired signals; the controlled object (3) receives the test excitation signals output by the main control board (1) and outputs response signals.

2. The electronic terminal transmission function testing system based on analog-to-digital conversion according to claim 1, characterized in that, The two analog-to-digital conversion channels are synchronously acquired under the same sampling clock. The test excitation signal is a sinusoidal sweep frequency signal; Each digital-to-analog conversion channel includes at least one DA module; each analog-to-digital conversion channel includes at least one AD module.

3. A method for testing the transmission function of an electronic terminal based on analog-to-digital conversion, characterized in that, The method is implemented based on the system described in any one of claims 1 to 2, and the method includes the following steps: S1, the host computer (2) sets a frequency table, generates and transmits test instructions to the main control board (1), the test instructions include at least a sweep frequency range and an excitation amplitude; S2, the analog-to-digital conversion channel of the main control board (1) outputs a test excitation signal according to the test instructions; the test excitation signal is divided into two paths, one path input to the controlled object (3) and the other path input to the first analog-to-digital conversion channel of the main control board (1); S3, after receiving the test excitation signal, the controlled object (3) outputs a response signal to the second analog-to-digital conversion channel of the main control board (1); S4, the main control board (1) uses the test excitation signal collected by the first analog-to-digital conversion channel and the response signal collected by the second analog-to-digital conversion channel as sampling signals, and transmits them together with the frequency index value of the sampling signals to the host computer (2); S5, the host computer (2) performs steady-state screening on the sampling signals, and performs parameterization processing on the sampled signals after steady-state screening to obtain the amplitude of the steady-state response signal. and phase S6, host computer (2) plots amplitude-frequency characteristic curve and phase-frequency characteristic curve based on the amplitude and phase parameters of the steady-state response signal.

4. The electronic terminal transmission function testing method based on analog-to-digital conversion according to claim 3, characterized in that, The parameterization process includes: S51, looking up the frequency table based on the frequency index value of the sampled signal to obtain the current theoretical frequency value; S52, deducing the steady-state response signal voltage value based on the steady-state response signal; S53, calculating the current actual frequency value based on the steady-state response signal using a fast Fourier transform. S54. Construct a sinusoidal model and fit the steady-state response signal; S55. Based on the sinusoidal model, construct the observation matrix, and solve the observation matrix using the linear least squares method to obtain the amplitude of the steady-state response signal. With phase 。 5. The electronic terminal transfer function testing method based on analog-to-digital conversion according to claim 4, characterized in that, The formula for calculating the voltage value of the inverse steady-state response signal is: ,in, This indicates the test excitation signal received by the first analog-to-digital conversion channel. This indicates the response signal received by the second analog-to-digital conversion channel. Indicates the reference voltage of the AD module. Indicates the resolution of the AD module. Indicates circuit gain. This indicates the voltage value of the input signal to the controlled object (3). The voltage value of the output signal of the controlled object (3); the actual frequency value The formula for calculation is: ,in, This represents the index of the frequency point with the largest amplitude in the steady-state response signal after processing by the Fast Fourier Transform. Indicates the sampling rate. Indicates the number of sampling points.

6. The electronic terminal transmission function testing system based on analog-to-digital conversion according to claim 5, characterized in that, The sinusoidal model is specifically as follows: ,in, Represents the steady-state response signal angular frequency, through calculate, The time series representing the steady-state response signal. The bias represents the steady-state response signal; the observation matrix is ​​specifically: The method of solving the observation matrix using linear least squares specifically involves: constructing the coefficient matrix to be solved. ;according to 、 Construct an error function using the steady-state response signal voltage value: ,in, Represents the steady-state response signal voltage value, including and ;right Find the derivative and set it to zero to solve the problem. 、 and ;according to 、 and Solution 、 and ： ； ； 。 7. The electronic terminal transmission function testing system based on analog-to-digital conversion according to claim 6, characterized in that, Specifically for and By executing steps S53 to S55, the amplitude input by the controlled object (3) can be obtained. The phase input of the controlled object (3) The amplitude of the output of the controlled object (3) and the phase output of the controlled object (3) ； 、 、 and The amplitude of the steady-state response signal With phase 。 8. The electronic terminal transmission function testing system based on analog-to-digital conversion according to claim 7, characterized in that, The amplitude-frequency response curve is specifically as follows: The phase frequency response curve is specifically as follows: 。 9. The electronic terminal transmission function testing system based on analog-to-digital conversion according to claim 8, characterized in that, The steady-state screening specifically involves selecting the sampling signal from the second half of the total sampling period as the steady-state response signal.

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