High-accuracy sinusoidal signal measuring method for removing frequency spectrum leakage

Abstract

The invention discloses a high-accuracy sinusoidal signal measuring device for removing frequency spectrum leakage, comprising an analog signal pre-processing unit, a data acquisition unit, a digital signal processing unit, a measuring result display unit, and a communication interface unit, wherein the analog signal pre-processing unit is connected with the data acquisition unit through multipath signal wires, and the digital signal processing unit is connected with the data acquisition unit, the measuring result display unit and the communication interface unit respectively through an SPI (Serial Peripheral Interface) bus. The measuring method comprises the steps of: 1, continuously sampling a signal to be measured to obtain sequences S1 and S2; 2, carrying out fast Fourier transform onthe S1, extracting a peak frequency spectrum and obtaining the peak frequency spectrum of the S2 through recursion; 3, calculating the frequency of the signal to be measured by applying the peak frequency spectrums of the S1 and the S2; 4, calculating the phase of the signal to be measured according to the phase angle information of the peak frequency spectrums of the S1 and S2; 5, solving an equation set relevant to positive and negative frequency spectrum amplitudes to obtain the measured value of the amplitude of the signal to be measured; and 6, removing the influence of the frequency spectrum leakage to obtain the accurate measured valve of a direct-current component.

Description

1. Technical field [0001] The invention relates to a high-accuracy sinusoidal signal measurement method and device for eliminating spectrum leakage, and belongs to the technical field of signal measurement. 2. Background technology [0002] In industrial fields such as electrical measurement, power grid monitoring, vibration and noise measurement, audio processing and radar signal processing, it is often necessary to perform high-precision measurement of various parameters of sinusoidal signals. For example, precision electric energy metering needs to accurately measure the amplitude of the sinusoidal signal, monitoring the frequency fluctuation of the power grid needs to accurately measure the frequency of the sinusoidal wave in real time, and using a Coriolis flowmeter to detect the flow of liquid and accurate distance measurement by radar requires accurate measurement of the phase difference of the sinusoidal signal , calculating the DC loss of the transformer requires me...

AI Technical Summary

Problems solved by technology

[0007] (2) The traditional measurement device is highly dependent on the hardware, and hardware characteristics such as clock stability and device-to-signal delay seriously restrict the measurement accuracy of the traditional measurement device

[0008] (3) The traditional measurement device has a low degree of automation and poor adaptability to the input signal amplitude, and cannot automatically adjust the gain coefficient of the signal amplifier according to the size of the signal to be measured

The above method has the following disadvantages: First, the iterative process needs to repeatedly reconstruct the negative frequency spectrum, which requires a large amount of calculation

Second, three spectral lines are required for measurement, so it is impossible to distinguish the signal at the frequency between the first and third spectral lines, which reduces the frequency resolution of the algorithm

However, this method has the following disadvantages: First, three spectral lines are required for measurement, so it is impossible to distinguish the signal at the frequency between the frequency points corresponding to the first and third spectral lines, which reduces the frequency resolution of the algorithm

Second, this method is an approximate algorithm, which is only applicable to the case where the number of sampling points is large. When the number of sampling points is small, the algorithm error is large

Second, the above-mentioned patented method uses the two spectral lines with the largest and second largest amplitudes in the spectrum, so it is impossible to distinguish the frequency signal between the frequency points corresponding to the two spectral lines, which reduces the frequency resolution of the algorithm

Third, when using the above-mentioned patented method to measure low-frequency signals, when the number of sampling points is low, there will be singularity, resulting in data overflow, and it is impossible to measure the parameters of the signal. However, this method does not have such a singularity and can still maintain high accuracy. As shown in Table 2a, Table 2b and Table 2c

Fourth, the above-mentioned patent method does not provide the measurement method of the DC component, and the high-accuracy measurement values ​​of all four parameters of the sinusoidal signal can be obtained by using the method of the present invention

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