[0019] Hereinafter, the present invention will be further described in detail through specific embodiments in conjunction with the drawings.
[0020] The method, device and system of the present application are applicable to waveform generators. In the embodiments of the present application, arbitrary waveform generators are taken as an example for description. In other embodiments, they are also applicable to other specific waveform generators, such as sine waves and sawtooth waves. Generator etc.
[0021] Please refer to figure 2 , This embodiment discloses a structural schematic diagram of a waveform generator frequency response characteristic calibration system. The system includes: a power meter 3 and a frequency response characteristic calibration device 1, wherein the power meter 3 is used to communicate with the waveform generator 2 to be calibrated. Connected, the power meter 3 detects the designated frequency point f of the waveform generator to be calibrated 2 n The actual output amplitude of the frequency response The frequency response characteristic calibration device 1 is connected to the signal of the power meter 3, and the power meter 3 will detect the actual output amplitude of the frequency response Output to frequency response characteristic calibration device 1, which is based on the actual output amplitude of the acquired frequency response Proceed accordingly. In a specific embodiment, the frequency response characteristic calibration device 1 according to the actual output amplitude After processing, get the designated frequency point f n And write the calibration data into the waveform generator 2 to be calibrated, so as to specify the frequency point f for the waveform generator 2 n Calibration.
[0022] Please refer to Figure 3a , Is a schematic diagram of the output signal of the frequency response characteristic of a waveform generator, Figure 3a Among them, the dashed line represents the ideal frequency response curve, and the solid line is the actual frequency response characteristic curve of the waveform generator. Generally, the output signal of the waveform generator is in a nominal fixed frequency band at each designated frequency point f in the corresponding frequency band. 1 , F 2 , F 3 ……F n-2 , F n-1 , F n When calibrating, use standard test equipment to measure the actual amplitude data of each designated frequency point, and then calculate the actual gain value corresponding to each designated frequency point according to the input and output relationship, that is, the frequency response error data of each designated frequency point: Δd 1 , Δd 2 , Δd 3 ,..., Δd n-2 , Δd n-1 , Δd n , Use the response error as calibration data to configure the multiplier, so as to achieve calibration compensation for each designated frequency point, where f n Indicates the nth designated frequency point in the frequency band, Δd n Indicates the frequency response error of the nth designated frequency point in the frequency band. Theoretically, after configuring these frequency response error data as calibration data to the multiplier of the signal channel, good signal flatness can be obtained. However, in fact, when using standard test equipment to test the output of the signal channel after the frequency response calibration data is configured, it is found that the frequency response curve of the signal channel after calibration and compensation is still lower than the ideal frequency response curve, which is larger than the expected response curve. Deviation, such as Figure 3b As shown, Figure 3b The dotted line is the frequency response curve of the signal channel after calibration and compensation. There are two reasons for this phenomenon: First, because the specific operation of frequency response data calibration compensation is to adjust and increase the gain of the multiplier according to the frequency response compensation data to compensate for the actual signal channel frequency response curve to the ideal frequency response curve Because the bandwidth of the multiplier will decrease with the increase of its gain, the frequency response curve will also steeply drop with the increase of the output signal amplitude. Second, after the frequency response compensation, the multiplication The amplitude of the signal output from the amplifier to the amplitude control circuit increases, resulting in an increase in the output signal amplitude of the operational amplifier in the amplitude control circuit, and the operational amplifier also has the basic characteristics of increasing the frequency response curve as the signal output amplitude increases. . Based on the above two reasons, the generator cannot get good amplitude flatness.
[0023] For this reason, the embodiment of the present application improves the frequency response characteristic calibration device 1 to improve the flatness of the amplitude of the frequency response characteristic of the waveform generator. Please refer to Figure 4 , This embodiment discloses a schematic structural diagram of a calibration device for frequency response characteristics of a waveform generator. The calibration device includes: an ideal amplitude acquisition module 11, an actual amplitude acquisition module 12, a frequency response error calculation module 13, a judgment module 14, The calibration data determination module 15 and the compensation module 16, wherein,
[0024] The ideal amplitude acquisition module 11 is used to acquire the designated frequency point f of the waveform generator to be calibrated n Ideal output amplitude of frequency response The actual amplitude acquisition module 12 is used to acquire the designated frequency point f n The actual output amplitude of the frequency response at the current moment The frequency response error calculation module 13 is used to calculate according to the specified frequency point f n Actual output amplitude at current moment And ideal output amplitude Calculate the designated frequency point f n Frequency response error at current moment among them, Indicates the nth designated frequency point f n The actual output amplitude at the i-th moment; the judgment module 14 is used to judge the frequency response error at the current moment Is it less than or equal to the preset threshold, where, Indicates the nth designated frequency point f n The frequency response error at the i-th moment; the calibration data determining module 15 is used to determine the specified frequency point f when the judgment module judges yes n Provided calibration data Δd n Is the sum of the frequency response error at the current time and the previous time; the compensation module 16 is used to send the designated frequency point f when the judgment module judges no n Provide the sum of the frequency response errors at the current time and the previous time as the compensation data at the next time for the specified frequency point f n Make compensation.
[0025] In a specific embodiment, the device for calibrating the frequency response characteristics of the waveform generator further includes: a designated frequency selection module 17, and the designated frequency selection module 17 is used to select the required frequency band of the waveform generator to be calibrated according to a preset rule Multiple designated frequency points f n.
[0026] In a specific embodiment, the waveform generator frequency response characteristic calibration device further includes: a non-designated frequency point calibration module 18, and the non-designated frequency point calibration module 18 is used to calibrate each designated frequency point adjacent to the non-designated frequency point. f n The calibration data of the non-specified frequency point is obtained by fitting the calibration data.
[0027] In a specific embodiment, the device for calibrating the frequency response characteristics of the waveform generator further includes: a calibration data output module 19, and the calibration data output module 19 is used to output a specified frequency point f to the waveform generator to be calibrated. n Calibration data Δd n.
[0028] Based on the above-mentioned waveform generator frequency response characteristic calibration device, this embodiment also discloses a waveform generator frequency response characteristic calibration method, please refer to Figure 5 , Is the flow chart of the calibration method, which includes the following steps:
[0029] Step S100, an ideal amplitude obtaining step. Get the specified frequency point f of the waveform generator to be calibrated n Ideal output amplitude of frequency response In a specific embodiment, the ideal output amplitude Can be preset by the system. In the calibration of the waveform generator, the frequency response characteristic curve usually adopts a sine wave signal. In other embodiments, other signals may be decomposed into sine wave signals, or not decomposed. Those skilled in the art should understand that, in specific embodiments, no matter what signal is used for calibration, different designated frequency points f n Corresponding ideal output amplitude Should be the same.
[0030] Step S200, the actual amplitude obtaining step. Get the specified frequency point f n The actual output amplitude of the frequency response at the current moment After the user selects an appropriate amplitude and triggers the waveform generator, the signal channel of the waveform generator will output an actual frequency response signal. At this time, the specified frequency point f can be detected and acquired. n The actual output amplitude of the frequency response at the current moment
[0031] The execution sequence of step S100 and step S200 is not limited. It should be noted that in the frequency response characteristics of non-step response, the ideal output amplitude And actual output amplitude There should be a corresponding relationship, that is, the nth designated frequency point f n Ideal output amplitude And the nth designated frequency point f n Actual output amplitude There is a one-to-one correspondence.
[0032] Step S300, frequency response error calculation step. According to the specified frequency point f n Actual output amplitude at current moment And ideal output amplitude Calculate the designated frequency point f n Frequency response error at current moment among them, Is the amplitude of the frequency response characteristic output by the waveform generator at the current moment (such as the i-th moment), Is the frequency response characteristic error output by the waveform generator at the current moment (such as the i-th moment). In a specific embodiment, the frequency response error at the current moment You can use the difference calculation: Of course, in other embodiments, it can also be obtained in other alternative ways, such as the actual output amplitude And ideal output amplitude Take the absolute value for the difference.
[0033] Step S400, a judgment step. Determine the frequency response error at the current moment Whether it is less than or equal to the preset threshold W, if the judgment is yes, then step S510 is executed; if the judgment is no, then step S520 is executed. In a specific embodiment, the preset threshold W may be set in the system based on experience or accuracy requirements. The smaller the preset threshold W, the higher the accuracy.
[0034] Step S510, calibration data determination step. Determine to the designated frequency point f n Provided calibration data Δd n It is the sum of the frequency response errors at the current time and the previous time. specifically, which is Δ d n = Δ d n 1 + Δ d n 2 + Δ d n 3 + . . . + Δ d n i , among them, Is the frequency response error at the time before the current time (the i-th time).
[0035] Step S520, a compensation step. To the designated frequency point f n Provide the sum of the frequency response errors at the current time and the previous time as the compensation data at the next time for the specified frequency point f n Make compensation. The waveform generator will continue to output the frequency response signal after compensation. At this time, repeat steps S200, S300 and S400: get the actual output amplitude of the frequency response after compensation at the next time, calculate the frequency response error at the next time, and judge Whether the frequency response error at the next moment is less than the preset threshold, perform the corresponding operation according to the judgment result.
[0036] It should be noted that the frequency response error is determined in step S400 When it is greater than the preset threshold W, the error at the current time and the error at the previous time are superimposed and compensated to the specified frequency point f n , Until the frequency response error of the waveform generator is less than or equal to the preset threshold W, it is determined that the sum of the error at this time and the previous error is the designated frequency f n Calibration data.
[0037] The output signal of the waveform generator is in a nominal frequency band. There are many different frequency points distributed in this frequency band. Under normal circumstances, it is not necessary to perform the above-mentioned calibration for each frequency point in the frequency band. Therefore, you can select an appropriate In a preferred embodiment, before performing step S200, it may further include:
[0038] Step S600, a step of selecting a designated frequency point. Please refer to Image 6 , Can select multiple designated frequency points f on the required frequency band of the waveform generator to be calibrated according to preset rules 1 , F 2 , F 3 ……F n-2 , F n-1 , F n. Then select each designated frequency point f n Calibrate separately. In a specific embodiment, the selection of multiple designated frequency points may be equal or unequal selection. The selected number of designated frequency points can be set as required. The more designated frequency points, the higher the accuracy.
[0039] In a specific embodiment, after the calibration data of each designated frequency point in the frequency band is obtained, other non-designated frequency points in the frequency band may be calibrated according to the calibration data of each designated frequency point in the frequency band. Specifically, it may include:
[0040] Step S700, a non-designated frequency point calibration step. According to the designated frequency points adjacent to the non-designated frequency point f n The calibration data of the non-specified frequency point is obtained by fitting the calibration data. In a specific embodiment, calibration can be performed based on the calibration data of the designated frequency point closest to the non-designated frequency point. In another embodiment, the calibration can also be performed based on the calibration data of all designated frequency points in the frequency band. calibration. Among them, the fitting method can adopt existing methods such as linear interpolation to obtain the calibration data of the non-specified frequency point. It should be noted that the more dense the selection of designated frequency points in the frequency band, the higher the fitting accuracy.
[0041] In a specific embodiment, after the calibration data of the specified frequency point is obtained, the calibration data may be sent to the waveform generator for the waveform generator to provide calibration data to the multiplier. Specifically, it may further include:
[0042] Step S800, calibration data output step. Output the specified frequency point f to the waveform generator to be calibrated n Calibration data Δd n. In one embodiment, the calibration data of each designated frequency point can be output to the waveform generator after the calibration data of all designated frequency points are obtained; in another embodiment, it can also be calculated every time a designated frequency point f n Calibration data Δd n , Then the designated frequency f n Calibration data Δd n Output to the waveform generator. In other embodiments, the calibration data of non-designated frequency points may also be output to the waveform generator.
[0043] Usually, the waveform generator will be equipped with a memory to store calibration data. When a certain waveform in the waveform generator is triggered, the CPU in the waveform generator will call the corresponding calibration data to the multiplier, thereby realizing the output signal Calibration.
[0044] The waveform generator calibration method disclosed in this embodiment obtains the calibration data of the signal channel of the waveform generator by adopting a successive approximation calibration method, so that the difference between the calibrated signal channel gain characteristic and the ideal frequency response curve converges to the desired Within the accuracy, the calibration accuracy is improved, and then the flatness of the amplitude of the frequency response characteristic of the waveform generator is improved.
[0045] Those skilled in the art can understand that all or part of the steps of the various methods in the above-mentioned embodiments can be completed by a program instructing relevant hardware. The program can be stored in a computer-readable storage medium. The storage medium can include: read-only memory, Random access memory, magnetic disk or CD, etc.
[0046] The above uses specific examples to illustrate the present invention, which are only used to help understand the present invention and not to limit the present invention. For those skilled in the art to which the present invention belongs, based on the idea of the present invention, several simple deductions, modifications or substitutions can also be made.
