A digital sampling trigger delay accurate measurement and correction method

Abstract

The present invention discloses a digital sampling trigger delay accurate measurement method, which is used to solve the problem of high-precision vector measurement error caused by trigger delay. Trigger error evaluation can be completed by using only a high-precision signal source, eliminating the complex multi-device debugging, simplifying the evaluation process, and flexibly selecting the trigger edge mode to adapt to different measurement environments. At the same time, a pulse signal trigger delay correction method is also provided to overcome the problem of differences in sampling time delays under different trigger thresholds caused by sampling bandwidth and digital trigger mechanism.

Description

Technical Field

[0001] The invention belongs to the field of precise measurement of alternating current signals, and in particular relates to a method for precise measurement and correction of digital sampling trigger delay. Background Art

[0002] In high-precision measurement and control systems, trigger mechanisms are used to start signal acquisition at a specific time or event, such as hardware triggers and software triggers widely used in data acquisition, test measurement, and control systems. The trigger mechanism is one of the key technologies to achieve system synchronous operation. As the system operating frequency increases, the trigger mechanism has higher and higher requirements for accuracy and consistency. However, due to factors such as clock jitter, hardware delay, software response time, and signal noise, trigger delay errors are inevitable. These errors will directly reduce the stability of the system and the accuracy of the measurement. Therefore, accurately evaluating the size of the trigger error plays a key role in achieving high-precision measurement.

[0003] Vector measurement technology can simultaneously measure the amplitude and phase of a signal. It is widely used in power systems, communications, radio frequency technology and other fields to provide a more comprehensive signal feature analysis. Through vector measurement, the system can more accurately capture the frequency changes, phase jitter and noise of the signal, thereby improving measurement accuracy and system stability. In power systems, vector measurement technology is used in phasor measurement units to achieve synchronous acquisition of voltage and current phasors at different nodes. These data are crucial for grid state estimation, fault detection and stability analysis to ensure the stable operation of the grid.

[0004] Vector measurement technology greatly improves the accuracy and dynamic response capability of the system by comprehensively analyzing the amplitude and phase of the signal. However, the trigger delay error will affect the accuracy of the vector measurement and weaken the credibility of the measurement results. Therefore, evaluating the trigger delay error is crucial to ensure high-precision vector measurement and overall system performance. Summary of the invention

[0005] The purpose of the present invention is to provide a digital sampling trigger delay accurate measurement method for solving the problem of high-precision vector measurement error caused by trigger delay. At the same time, a pulse signal trigger delay correction method is also provided to overcome the problem of sampling time delay differences under different trigger thresholds caused by sampling bandwidth and digital trigger mechanism.

[0006] In a first aspect, the present invention provides a method for accurately measuring a digital sampling trigger delay, comprising the following steps:

[0007] 11) Use a high-precision signal source with an output frequency of f 0 , the amplitude is A 0 A high-frequency standard sine signal is input to the trigger port and the sampling port at the same time.

[0008] 12) Set the trigger edge mode (rising edge or falling edge) and trigger threshold v, as well as the sampling rate f s The sampling rate satisfies the Nyquist sampling theorem. The sinusoidal signal is sampled through the trigger mechanism to obtain the sampling sequence x(n);

[0009] 13) Perform Fourier transform on the sampling sequence x(n) and calculate the initial phase of the sinusoidal signal

[0010] 14) Calculate the ideal initial phase according to the trigger edge mode and trigger threshold v

[0011] 15) By comparing the actual initial phase and the ideal initial phase Get the phase difference

[0012] 16) According to the sinusoidal signal frequency f 0 , the phase difference Convert to time difference That is, the sampling rate is f s The trigger delay error is as follows.

[0013] The beneficial effects are: trigger error evaluation can be completed by using only a high-precision signal source, eliminating the need for complex multi-device debugging and simplifying the evaluation process. This method can accurately evaluate the trigger error and solve the impact of trigger delay on high-precision vector measurement, thereby improving the overall measurement accuracy of the system.

[0014] Furthermore, in step 11), the signal output by the signal source is transmitted to the trigger port and the sampling port using equal-length connecting lines, and the time error can be ignored.

[0015] The beneficial effect is that through this synchronous transmission mode, it is ensured that the trigger signal and the sampling signal come from the same signal source, and there is no delay difference between the trigger signal and the sampling signal, which effectively avoids measurement errors caused by signal asynchrony or inconsistency.

[0016] Furthermore, in step 12), the trigger edge mode can be selected as rising edge trigger or falling edge trigger, and the sampling frequency f s is the standard sinusoidal signal frequency f 0 An integer multiple of .

[0017] The beneficial effect is: flexible selection of trigger edge mode to adapt to different measurement environments. In the case of source meter synchronization, by selecting the standard sine signal frequency f 0 The sampling rate f is an integer multiple of s, which reduces the calculation error caused by non-integer cycle sampling and further improves the evaluation accuracy of trigger delay.

[0018] Further, in step 14), when the trigger edge is selected as the rising edge trigger, the ideal initial phase When the trigger edge is selected as the falling edge trigger, the ideal initial phase

[0019] In a second aspect, the present invention further provides a delay correction method based on pulse triggering, comprising the following steps:

[0020] 21) Set the pulse trigger edge mode (rising edge or falling edge) and the sampling amplitude to A 1 , the initial phase is The frequency is f 1 The sine signal is set to the sampling rate f s , this sampling rate satisfies the Nyquist sampling theorem.

[0021] 22) Select multiple trigger thresholds v(n), sample and measure the sinusoidal signal, and obtain the initial phase sequence of the sinusoidal signal corresponding to different trigger thresholds Calculate the difference between the initial phase measurement and the ideal value

[0022] 23) According to the sinusoidal signal frequency f 1 The initial phase difference sequence Convert to time series

[0023] 24) Subtract the trigger delay error Δt′ measured in step 16) from the time series 1 Get the time difference Δt between the sine signal and the trigger signal 1 (n) = t 1 (n)-Δt′ 1 .

[0024] 25) Change the sampling rate to f s2 Repeat steps 11) to 24) to obtain a sampling rate of f s2 The measured trigger delay error Δt′ 2 The time difference between the sine signal and the trigger signal Δt 2 (n). Comparison with Δt 1 (n) and Δt 2 (n), where Δt 1 (n) and Δt 2(n) is equal to the trigger threshold value corresponding to the actual trigger point. In the subsequent trigger measurement, the delay of the trigger point is the delay measured at the corresponding sampling rate in steps 11) to 16), which can be directly corrected. The delay errors corresponding to other trigger thresholds cannot be directly corrected.

[0025] Furthermore, in step 21), the sinusoidal signal output by the high-precision signal source is phase-locked with the trigger signal. The time difference between the sinusoidal signal output by the high-precision signal source and the trigger signal is a fixed value, and the change is negligible.

[0026] Furthermore, in step 22) and step 25), the trigger signal is a rising edge or falling edge trigger mode, and the rising edge or falling edge time is much smaller than the sampling interval time 1 / f s Due to the influence of sampling bandwidth and digital trigger sampling, the time difference corresponding to the initial phase obtained by different sampling thresholds may differ by several sampling intervals 1 / f s . BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the method for accurately measuring the delay of digital sampling triggering of the present invention;

[0028] Figure 2 A flow chart of a method for correcting pulse signal trigger delay of the present invention; Specific implementation plan

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] An embodiment of a digital sampling trigger delay accurate measurement method:

[0031] like Figure 1 As shown, this embodiment proposes a digital sampling trigger delay accurate measurement method, comprising the following steps:

[0032] Step 11: Use a high-precision signal source to output a high-frequency standard sine signal, and input the signal to the trigger port and the sampling port at the same time. The standard sine signal frequency is f 0 , the amplitude is A 0 .

[0033] Step 12: Set the trigger edge mode and trigger threshold v, as well as the sampling rate f s , the trigger edge mode is rising edge or falling edge. The sampling rate satisfies the Nyquist sampling theorem, and the sampling rate f s The standard sinusoidal signal frequency is f 0 The sinusoidal signal is sampled through the trigger mechanism to obtain the sampling sequence x(n);

[0034] Step 13: Perform Fourier transform on the sampling sequence x(n) and calculate the initial phase of the sinusoidal signal

[0035] Step 14: Calculate the ideal initial phase based on the trigger edge mode and trigger threshold v

[0036] Step 15: By comparing the actual initial phase and the ideal initial phase Get the phase difference When the trigger edge is selected as rising edge trigger, the ideal initial phase When the trigger edge is selected as the falling edge trigger, the ideal initial phase

[0037] Step 16: According to the standard sinusoidal signal frequency f 0 , the phase difference Convert to time difference That is, the sampling rate is f s The trigger delay error is as follows.

[0038] The embodiment of the present invention further provides a delay correction method based on pulse triggering, comprising the following steps:

[0039] Step 21: Select a signal source with a fixed time difference between the output sine signal and the trigger signal and negligible changes, and a trigger signal with a rising or falling edge time much smaller than the sampling time interval. Set the pulse trigger edge mode to rising edge or falling edge, and the sampling amplitude to A 1 , the initial phase is The frequency is f 1 The sine signal is set to the sampling rate f s , this sampling rate satisfies the Nyquist sampling theorem.

[0040] Step 22: Select multiple trigger thresholds v(n), sample and measure the sinusoidal signal, and obtain the initial phase sequence of the sinusoidal signal corresponding to different trigger thresholds. Calculate the difference between the initial phase measurement and the ideal value

[0041] Step 23: According to the frequency f of the sinusoidal signal 1 The initial phase difference sequence Convert to time series

[0042] Step 24: Subtract the trigger delay error Δt′ measured in step 16) from the time series 1 Get the time difference Δt between the sine signal and the trigger signal 1(n) = t 1 (n)-Δt′ 1 .

[0043] Step 25: Change the sampling rate to f s2 Repeat steps 11) to 24) to obtain a sampling rate of f s2 The measured trigger delay error Δt′ 2 The time difference between the sine signal and the trigger signal Δt 2 (n). Comparison with Δt 1 (n) and Δt 2 (n), where Δt 1 (n) and Δt 2 (n) is equal to the trigger threshold value corresponding to the actual trigger point. In the subsequent trigger measurement, the delay of the trigger point is the delay measured at the corresponding sampling rate in steps 11) to 16), which can be directly corrected. The delay errors corresponding to other trigger thresholds cannot be directly corrected.

[0044] The above embodiments further illustrate the features and advantages of the technical solution of the present invention. Those skilled in the art can design more specific implementations without departing from the scope of the technical solution of the present invention. However, these embodiments designed according to the present invention should all fall within the scope of protection of the claims of the present invention.

Claims

1. A digital sampling trigger delay accurate measurement method, characterized in that: The following steps are involved: 11) Use a high-precision signal source to output a high-frequency standard sine signal with a frequency of f0 and an amplitude of A0, and input the signal to the trigger port and the sampling port at the same time; 12) Set the trigger edge mode and trigger threshold v, as well as the sampling rate f s , the sampling rate satisfies the Nyquist sampling theorem, and the sinusoidal signal is sampled through the trigger mechanism to obtain the sampling sequence x(n); 13) Perform Fourier transform on the sampling sequence x(n) and calculate the initial phase of the sinusoidal signal 14) Calculate the ideal initial phase according to the trigger edge mode and trigger threshold v 15) By comparing the actual initial phase and the ideal initial phase Get the phase difference 16) According to the frequency f0 of the sinusoidal signal, the phase difference Convert to time difference That is, the sampling rate is f s The trigger delay error is as follows.

2. A digital sampling trigger delay accurate measurement method according to claim 1, wherein: The trigger edge mode includes rising edge trigger or falling edge trigger, and the sampling rate is f s It is an integer multiple of the standard sinusoidal signal frequency f0.

3. A digital sampling trigger delay accurate measurement method according to claim 2, wherein in step 14), when the trigger edge is selected as a rising edge trigger, the ideal initial phase When the trigger edge is selected as the falling edge trigger, the ideal initial phase 4. A method for correcting the delay measured by the digital sampling trigger delay accurate measurement method according to any one of claims 1 to 3 based on pulse triggering, characterized in that: The following steps are involved: 21) Set the pulse trigger edge mode, the sampling amplitude is A1, and the initial phase is A sine signal with a frequency of f1 and a sampling rate of f s , the sampling rate satisfies the Nyquist sampling theorem; 22) Select multiple trigger thresholds v(n), sample and measure the sinusoidal signal, and obtain the initial phase sequence of the sinusoidal signal corresponding to different trigger thresholds Calculate the difference between the initial phase measurement and the ideal value 23) According to the sinusoidal signal frequency f1, the initial phase difference sequence Convert to time series 24) Subtract the trigger delay error Δt′1 measured in step 16) from the time series to obtain the time difference between the sinusoidal signal and the trigger signal Δt1(n)=t1(n)-Δt′1; 25) Change the sampling rate to f s2 Repeat steps 11)-16) and steps 21)-24) to obtain the sampling rate f s2 The measured trigger delay error Δt′2 and the time difference Δt2(n) between the sinusoidal signal and the trigger signal are compared with Δt1(n) and Δt2(n). The trigger threshold corresponding to the equality of Δt1(n) and Δt2(n) is the actual trigger point. In the subsequent trigger measurement, the delay of the trigger point is the delay measured in steps 11) to 16) at the corresponding sampling rate, which can be directly corrected. The delay errors corresponding to other trigger thresholds cannot be directly corrected.

5. The method according to claim 4, wherein: The sinusoidal signal output by the high-precision signal source is phase-locked with the trigger signal, and the time difference between the sinusoidal signal output by the high-precision signal source and the trigger signal is a fixed value.

6. The method according to claim 4, wherein: The trigger signal is a rising edge or falling edge trigger mode, and the rising edge or falling edge time is much smaller than the sampling interval time 1 / f s .

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