Automatic calibration system and calibration method for amplitude-frequency characteristic curve of data acquisition system

Abstract

The invention discloses an automatic calibration system and a calibration method for an amplitude-frequency characteristic curve of a data acquisition system, which are mainly used for solving the technical problems that the existing method for manually measuring the amplitude-frequency characteristic curve of the data acquisition system is time-consuming and labor-consuming in operation and slow in data processing, the number of measured frequency value points is limited, and the change rule at details cannot be accurately captured. The invention provides an automatic calibration system for an amplitude-frequency characteristic curve of a data acquisition system. The automatic calibration system comprises a signal source, a cable connector, a background data acquisition system and a control terminal, when background signals are measured, the signal source is connected with the background data acquisition system through the cable connector, and the control terminal is connected with the signal source and the background data acquisition system. When a combined signal is measured, a signal source is connected with a data acquisition system DUT to be measured through a cable connector; and the control terminal is connected with the signal source and the to-be-tested data acquisition system DUT and is used for setting parameters, realizing automatic calibration and effectively improving the data processing efficiency.

Description

Technical Field

[0001] The present invention relates to a method for calibrating an amplitude-frequency characteristic curve, and particularly to an automatic calibration system and method for the amplitude-frequency characteristic curve of a data acquisition system. Background Art

[0002] Data acquisition systems are widely used in electronic measuring instruments. Whether in scientific research, engineering applications, or social life, medical and health fields, etc., high-speed, medium-speed, or low-speed data acquisition is involved. The analog input bandwidth (also called analog bandwidth, 3dB bandwidth, -3dB bandwidth, bandwidth, etc.) is a core performance parameter of a data acquisition system. To determine the analog input bandwidth of a data acquisition system, it is necessary to measure the amplitude-frequency characteristic curve (also called amplitude-frequency response characteristic curve, amplitude-frequency curve, Bode plot, baud plot, etc.) of the data acquisition system. The amplitude-frequency characteristic curve describes the response of the data acquisition system to signals of different frequencies, usually represented by a curve of the amplitude of the output signal varying with frequency. In the amplitude-frequency characteristic curve, the -3dB point marks the boundary of the effective frequency range of the data acquisition system, and the frequency value corresponding to the -3dB amplitude is the analog input bandwidth of the data acquisition system, which reflects the highest frequency signal that the data acquisition system can effectively process.

[0003] When a data acquisition system leaves the factory, it will give a nominal bandwidth. Before users use it, they generally need to check whether the nominal bandwidth is accurate. To verify the nominal bandwidth, users need to measure the amplitude-frequency characteristic curve of the data acquisition system to obtain the measured bandwidth. In the prior art, an artificial measurement method is usually adopted, where the signal source is operated to output sine wave signals with set frequencies and set amplitudes one by one, the output of the signal source is connected to the input end of the data acquisition system, the measured amplitude of the output signal of the data acquisition system is measured manually, and logarithmic processing and normalization processing are performed according to the set frequency, set amplitude, and measured amplitude to obtain the amplitude-frequency characteristic curve.

[0004] This artificial measurement method is time-consuming and laborious in operation, slow in data processing, and the number of measured frequency value points is limited. The limited frequency points can only reflect the overall change trend of the amplitude-frequency characteristic curve and cannot accurately capture the change law in details. Summary of the Invention

[0005] The purpose of the present invention is to solve the technical problems that the existing method for manually measuring the amplitude-frequency characteristic curve of a data acquisition system is time-consuming and laborious in operation, slow in data processing, and the number of measured frequency value points is limited, and it is impossible to accurately capture the change law in details, and to propose an automatic calibration system and method for the amplitude-frequency characteristic curve of a data acquisition system.

[0006] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0007] An automatic calibration system for the amplitude-frequency characteristic curve of a data acquisition system, characterized in that it includes a signal source, a cable connector, a background data acquisition system and a control terminal;

[0008] The output end of the signal source is connected to the input end of the cable connector through a transmission cable, and is used to output a standard sine wave;

[0009] The output end of the cable connector is connected to the input end of the background data acquisition system when measuring the background signal, and is used to be connected to the input end of the data acquisition system under test (DUT) when measuring the combined signal;

[0010] The control terminal is connected to the input end of the signal source and is used to adjust the frequency and amplitude parameters of the sine wave; the control terminal is bidirectionally connected to the background data acquisition system when measuring the background signal, and is used to control the sampling frequency of the background data acquisition system and obtain the measured background amplitude of the sampling data output by the background data acquisition system, so as to obtain the background amplitude-frequency characteristic curve of the signal source and the cable connector; the control terminal is used to be bidirectionally connected to the data acquisition system under test (DUT) when measuring the combined signal, control the sampling frequency of the data acquisition system under test (DUT), and obtain the measured combined amplitude of the sampling data output by the data acquisition system under test (DUT), so as to obtain the combined amplitude-frequency characteristic curve of the signal source, the cable connector and the data acquisition system under test (DUT); the control terminal is also used to subtract the background amplitude-frequency characteristic curve from the combined amplitude-frequency characteristic curve to obtain the amplitude-frequency characteristic curve of the data acquisition system, realizing the automatic calibration of the amplitude-frequency characteristic curve of the data acquisition system.

[0011] Further, the transmission cable is a radio frequency cable or a radio frequency phase-stable cable, and the transmission bandwidth of the transmission cable is higher than the sine wave frequency.

[0012] Further, the analog input bandwidth of the background data acquisition system is higher than the analog input bandwidth of the data acquisition system under test (DUT).

[0013] Further, the control terminal is based on the TekVisa tool library and adopts the SCPI instruction set.

[0014] The present invention also provides an automatic calibration method for the amplitude-frequency characteristic curve of a data acquisition system. Based on the above-mentioned automatic calibration system for the amplitude-frequency characteristic curve of a data acquisition system, it is characterized in that it includes the following steps:

[0015] S1. Connect the output end of the cable connector to the input end of the background data acquisition system, and measure the background amplitude-frequency characteristic curve of the signal source and the cable connector;

[0016] S1.1. Set the signal source to output N sine waves through the control terminal. The frequencies of the N sine waves are F1, F2... FN respectively; the amplitudes of the N sine waves are all A; the N sine waves reach the background data acquisition system through the cable connector.

[0017] S1.2. The background data acquisition system samples the sine waves with frequencies F1, F2... FN respectively and outputs N background sampling data.

[0018] S1.3. The control terminal collects the N background sampling data and performs digital processing on them to obtain N measured background amplitudes.

[0019] S1.4. Perform logarithmic processing and normalization processing on the corresponding N frequencies, measured background amplitudes, and amplitude A to obtain the background amplitude-frequency characteristic curve of the signal source and the cable connector.

[0020] S2. Connect the output end of the cable connector to the input end of the data acquisition system under test (DUT), and measure the combined amplitude-frequency characteristic curve of the signal source, the cable connector, and the data acquisition system under test (DUT).

[0021] S2.1. Set the signal source to output N sine waves through the control terminal. The frequencies of the N sine waves are F1, F2... FN respectively; the amplitudes of the N sine waves are all A; the N sine waves are input into the data acquisition system under test (DUT) through the cable connector.

[0022] S2.2. The data acquisition system under test (DUT) samples the sine waves and outputs N combined sampling data.

[0023] S2.3. The control terminal collects the N combined sampling data and performs digital processing on them to obtain the combined measured amplitudes.

[0024] S2.4. Perform logarithmic processing and normalization processing on the corresponding N frequencies, combined measured amplitudes, and amplitude A to obtain the combined amplitude-frequency characteristic curve of the signal source, the cable connector, and the data acquisition system under test (DUT).

[0025] S3. Subtract the background amplitude-frequency characteristic curve from the combined amplitude-frequency characteristic curve to obtain the amplitude-frequency characteristic curve of the data acquisition system.

[0026] S4. Perform normalization processing on the amplitude-frequency characteristic curve, and obtain the analog input bandwidth of the data acquisition system according to the first -3dB point of the amplitude-frequency characteristic curve after normalization processing, thereby completing the automatic calibration of the amplitude-frequency characteristic curve of the data acquisition system.

[0027] Further, in step S1.1, the amplitude A is on the order of 100mV.

[0028] Further, in step S1.1, the amplitude A is 1 / 10 to 1 / 5 of the full-scale input of the background data acquisition system or the data acquisition system under test DUT.

[0029] Further, in step S1.2 and step S2.2, coherent sampling is performed on the sine wave.

[0030] Further, in step S1.3 and step S2.3, the sampled data is digitally processed for peak detection or amplitude detection.

[0031] Further, for the normalization processing in steps S1.4 and S2.4, the reference point is the point where the frequency value is less than 20 MHz.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The present invention provides an automatic calibration system for the amplitude-frequency characteristic curve of a data acquisition system, including a signal source, a cable connector, a background data acquisition system, and a control terminal; when measuring the background signal, the signal source is connected to the background data acquisition system through the cable connector, and the control terminal is connected to the signal source and the background data acquisition system; when measuring the combined signal, the signal source is connected to the data acquisition system under test DUT through the cable connector; the control terminal is connected to the signal source and the data acquisition system under test DUT, and is used to set parameters to achieve automatic calibration, effectively improving the data processing efficiency.

[0034] 2. The present invention provides an automatic calibration method for the amplitude-frequency characteristic curve of a data acquisition system. By connecting the signal source to the background data acquisition system, the background amplitude-frequency characteristic curve is measured; by connecting the signal source to the data acquisition system under test, the combined amplitude-frequency characteristic curve is measured; the amplitude-frequency characteristic curve of the data acquisition system is obtained by the method of subtracting the background. The method of subtracting the background can effectively eliminate the measurement error introduced by external electronic components and increase the accuracy of the measurement data.

[0035] 3. The present invention provides an automatic calibration method for the amplitude-frequency characteristic curve of a data acquisition system. By setting a sufficient number of frequency points through the control terminal, the calibration accuracy is provided, and more details of the amplitude-frequency characteristic curve are obtained. At the same time, it effectively reduces the problems of time-consuming and laborious manual calibration and few frequency points. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flowchart of an embodiment of the automatic calibration method for the amplitude-frequency characteristic curve of the data acquisition system of the present invention;

[0037] Figure 2 It is a schematic structural diagram of the connection between the cable connector and the background data acquisition system in an embodiment of the automatic calibration system for the amplitude-frequency characteristic curve of the data acquisition system of the present invention;

[0038] Figure 3 This is a schematic diagram of the connection between the cable connector and the data acquisition system under test (DUT) in the embodiment of the automatic calibration system for the amplitude-frequency characteristic curve of the data acquisition system of the present invention;

[0039] Figure 4 This is a schematic diagram of the background amplitude-frequency characteristic curve, the combined amplitude-frequency characteristic curve, and the amplitude-frequency characteristic curve in the embodiment of the automatic calibration method for the amplitude-frequency characteristic curve of the data acquisition system of the present invention;

[0040] Figure 5 This is a comparison chart of the calibration results of the automatic calibration method for the amplitude-frequency characteristic curve of the data acquisition system of the present invention and the manual calibration method. Detailed implementation manners

[0041] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0042] The present invention provides an automatic calibration system for the amplitude-frequency characteristic curve of a data acquisition system, which is characterized in that it includes a signal source, a cable connector, a background data acquisition system, and a control terminal;

[0043] The output end of the signal source is connected to the input end of the cable connector through a transmission cable. The signal source is used to output a standard sine wave. In this embodiment, the signal source uses a sine wave generator SMA100B, and the frequency and amplitude of the output sine wave are stable and reliable. The transmission cable is a radio frequency cable or a radio frequency phase-stable cable, and the transmission bandwidth of the transmission cable is higher than the sine wave frequency.

[0044] The output end of the cable connector is connected to the input end of the background data acquisition system, or is used to be connected to the input end of the data acquisition system under test (DUT); the cable connector needs to have the characteristics of high bandwidth and low loss. The data acquisition system under test (DUT) can be an oscilloscope, a data acquisition board, or a data acquisition device. The analog input bandwidth of the background data acquisition system is higher than that of the data acquisition system under test (DUT) to ensure measurement accuracy.

[0045] As Figure 2 shown, the control terminal is connected to the input end of the signal source and is used to adjust the frequency and amplitude parameters of the sine wave; the control terminal is bidirectionally connected to the background data acquisition system and is used to control the sampling frequency of the background data acquisition system and obtain the measured amplitude of the sampling data output by the background data acquisition system; as Figure 3As shown, the control terminal is also used to be bidirectionally connected to the data acquisition system under test (DUT), to control the sampling frequency of the DUT, and to obtain the measured amplitude of the sampling data output by the DUT. The control terminal writes a program based on the TekVisa tool library and using the SCPI instruction set. In this embodiment, the control terminal uses the C# language to write the control program. In other embodiments, programming languages such as Python and C++ can also be used to realize the separate control of the signal source, the background data acquisition system, and the DUT, and the synchronous control of the three, so as to realize automatic calibration.

[0046] The present invention also provides a method for automatically calibrating the amplitude-frequency characteristic curve of a data acquisition system. Based on the above-mentioned automatic calibration system for the amplitude-frequency characteristic curve of a data acquisition system, as Figure 1 shown, it specifically includes the following steps:

[0047] S1. As Figure 2 shown, connect the output end of the cable connector to the input end of the background data acquisition system, and measure the background amplitude-frequency characteristic curve of the signal source and the cable connector;

[0048] The background amplitude-frequency characteristic curve refers to the amplitude response characteristic of the signal source or the cable connector at different frequencies. By measuring this curve, the signal attenuation or distortion of the signal source or the cable connector at different frequencies can be understood. The analog input bandwidth of the background data acquisition system is much higher than that of the DUT, which can ensure accurate capture of high-frequency signals, so as to more accurately measure the characteristics of the signal source or the cable connector.

[0049] S1.1. Set the signal source to output N sine waves through the control terminal. The frequencies of the N sine waves are F1, F2... FN respectively; the amplitudes of the N sine waves are all A; the N sine waves reach the background data acquisition system through the cable connector; where the amplitude A is in the order of 100 mV, or the amplitude A is 1 / 10 to 1 / 5 of the full-scale input of the background data acquisition system or the DUT, mainly used to measure the amplitude-frequency characteristic curve in the case of a small sine wave amplitude, to avoid data acquisition system overload or noise interference;

[0050] S1.2. The control terminal controls the background data acquisition system to perform coherent sampling on the sine waves with frequencies of F1, F2... FN respectively, and outputs N background sampling data, so that the sampling data is equivalently evenly distributed on the waveform of the sine wave;

[0051] S1.3. The control terminal collects the N background sampling data and performs peak detection or amplitude detection on them to obtain N measured background amplitudes;

[0052] S1.4. Logarithmically process and normalize the N corresponding frequencies, the measured background amplitudes, and the amplitude A one by one to obtain the background amplitude-frequency characteristic curve of the signal source and the cable connector.

[0053] S2. As Figure 3 shown, connect the output end of the cable connector to the input end of the data acquisition system under test (DUT), and measure the combined amplitude-frequency characteristic curve of the signal source, the cable connector, and the data acquisition system.

[0054] S2.1. Set the signal source to output N sine waves through the control terminal. The frequencies of the N sine waves are F1, F2... FN respectively; the amplitudes of the N sine waves are all A; the N sine waves are input to the data acquisition system under test (DUT) through the cable connector.

[0055] S2.2. The data acquisition system under test (DUT) performs coherent sampling on the sine waves and outputs N combined sampling data.

[0056] S2.3. The control terminal collects the N combined sampling data and performs peak detection or amplitude detection on them to obtain the combined measured amplitudes.

[0057] S2.4. Logarithmically process and normalize the N corresponding frequencies, the combined measured amplitudes, and the amplitude A one by one. The reference point in the normalization process is the point where the frequency value is less than 20 MHz to obtain the combined amplitude-frequency characteristic curve of the signal source, the cable connector, and the data acquisition system under test (DUT); if the sampling frequency of the data acquisition system under test (DUT) is relatively low, the frequency value point near direct current can be directly selected as the reference point.

[0058] S3. As Figure 4 shown, subtract the background amplitude-frequency characteristic curve from the combined amplitude-frequency characteristic curve to obtain the amplitude-frequency characteristic curve of the data acquisition system after background subtraction.

[0059] S4. Normalize the amplitude-frequency characteristic curve, and obtain the analog input bandwidth of the data acquisition system according to the first -3dB point of the amplitude-frequency characteristic curve after normalization, completing the automatic calibration of the amplitude-frequency characteristic curve of the data acquisition system.

[0060] As Figure 5 shown, automatic calibration has the advantages of a large number of calibration points, high efficiency, high accuracy, etc. Compared with the manual calibration method, the advantages are significant. The manual calibration method only obtains the general shape of the amplitude-frequency characteristic curve, while the automatic calibration method obtains more details of the amplitude-frequency characteristic curve.

Claims

1. An automatic calibration system for amplitude-frequency characteristic curve of a data acquisition system, characterized by: Including signal source, cable connector, background data acquisition system and control terminal; The output end of the signal source is connected to the input end of the cable connector through a transmission cable, and is used to output a standard sine wave; The output end of the cable connector is connected to the input end of the background data acquisition system when measuring the background signal, and is used to connect to the input end of the data acquisition system DUT to be tested when measuring the combined signal; The control terminal is connected to the input end of the signal source and is used to adjust the frequency and amplitude parameters of the sine wave; when measuring the background signal, the control terminal is bidirectionally connected to the background data acquisition system and is used to control the sampling frequency of the background data acquisition system and obtain the background measured amplitude of the sampling data output by the background data acquisition system, thereby obtaining the background amplitude-frequency characteristic curve of the signal source and the cable connector; when measuring the combined signal, the control terminal is used to bidirectionally connect to the data acquisition system DUT to be tested and control the sampling frequency of the data acquisition system DUT to be tested and obtain the combined measured amplitude of the sampling data output by the data acquisition system DUT to be tested, thereby obtaining the combined amplitude-frequency characteristic curve of the signal source, the cable connector and the data acquisition system DUT to be tested; the control terminal is also used to use the combined amplitude-frequency characteristic curve to subtract the background amplitude-frequency characteristic curve to obtain the amplitude-frequency characteristic curve of the data acquisition system, thereby realizing the automatic calibration of the amplitude-frequency characteristic curve of the data acquisition system.

2. The data acquisition system amplitude-frequency characteristic curve automatic calibration system according to claim 1, characterized in that: The transmission cable is a radio frequency cable or a radio frequency phase-stable cable, and the transmission bandwidth of the transmission cable is higher than the sine wave frequency.

3. The data acquisition system amplitude-frequency characteristic curve automatic calibration system according to claim 2, characterized in that: The analog input bandwidth of the background data acquisition system is higher than the analog input bandwidth of the data acquisition system under test (DUT).

4. The data acquisition system amplitude-frequency characteristic curve automatic calibration system according to claim 3, characterized in that: The control terminal is based on the TekVisa tool library and adopts the SCPI instruction set.

5. A method for automatically calibrating the amplitude-frequency characteristic curve of a data acquisition system, based on the automatic calibration system for the amplitude-frequency characteristic curve of a data acquisition system according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Connect the output end of the cable connector to the input end of the background data acquisition system, and measure the background amplitude-frequency characteristic curve of the signal source and the cable connector; S1.

1. Set the signal source to output N sine waves through the control terminal. The frequencies of the N sine waves are F1, F2...FN respectively. The amplitudes of the N sine waves are all A. The N sine waves reach the background data acquisition system through the cable connector. S1.2, the background data acquisition system samples the sine waves with frequencies F1, F2...FN respectively, and outputs N background sampling data; S1.3, the control terminal collects N background sampling data, and performs digital processing on the data to obtain N background measured amplitudes; S1.

4. Perform logarithmic processing and normalization processing on the one-to-one corresponding N frequencies and the background measured amplitudes, as well as the amplitude A, to obtain the background amplitude-frequency characteristic curve of the signal source and the cable connector; S2, connecting the output end of the cable connector to the input end of the data acquisition system DUT to be tested, and measuring the combined amplitude-frequency characteristic curve of the signal source, the cable connector and the data acquisition system DUT to be tested; S2.

1. Set the signal source to output N sine waves through the control terminal. The frequencies of the N sine waves are F1, F2...FN respectively. The amplitudes of the N sine waves are all A. The N sine waves are input to the data acquisition system DUT to be tested through the cable connector. S2.2, the data acquisition system DUT samples the sine wave and outputs N combined sampling data; S2.3, the control terminal collects N combined sampling data, and performs digital processing on them to obtain the combined measured amplitude; S2.4, logarithmically processing and normalizing the one-to-one corresponding N frequencies and combined measured amplitudes, as well as the amplitude A, to obtain a combined amplitude-frequency characteristic curve of the signal source, the cable connector, and the data acquisition system DUT to be tested; S3, using the combined amplitude-frequency characteristic curve to subtract the background amplitude-frequency characteristic curve to obtain the amplitude-frequency characteristic curve of the data acquisition system; S4. Normalize the amplitude-frequency characteristic curve, obtain the analog input bandwidth of the data acquisition system according to the first -3dB point of the amplitude-frequency characteristic curve after normalization, and complete the automatic calibration of the amplitude-frequency characteristic curve of the data acquisition system.

6. The method for automatically calibrating the amplitude-frequency characteristic curve of a data acquisition system according to claim 5, characterized in that: In step S1.1, the amplitude A is on the order of 100 mV.

7. The method for automatically calibrating the amplitude-frequency characteristic curve of a data acquisition system according to claim 5, characterized in that: In step S1.1, the amplitude A is 1 / 10 to 1 / 5 of the full-scale input of the background data acquisition system or the data acquisition system under test DUT.

8. The method for automatically calibrating the amplitude-frequency characteristic curve of a data acquisition system according to any one of claims 5 to 7, characterized in that: In step S1.2 and step S2.2, the sine wave is coherently sampled.

9. The method for automatically calibrating the amplitude-frequency characteristic curve of a data acquisition system according to claim 8, characterized in that: In step S1.3 and step S2.3, the sampled data is digitized for peak detection or amplitude detection.

10. The method for automatically calibrating the amplitude-frequency characteristic curve of a data acquisition system according to claim 9, characterized in that: In the normalization process in steps S1.4 and S2.4, the reference point is a point where the frequency value is less than 20 MHz.

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