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Frequency measuring method of alternating current signal

A frequency measurement and electrical signal technology, applied in the field of frequency measurement of AC signals, can solve the problems of inaccurate frequency measurement accuracy of AC signals and large amount of calculation, etc., achieve clear physical concepts, improve anti-interference ability, and reduce random errors Effect

Inactive Publication Date: 2013-04-10
NANJING UNIV OF POSTS & TELECOMM
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Problems solved by technology

[0003] The technical problem solved by the present invention is to propose a method for measuring the frequency of an AC signal, which can also be used for fixed Frequency measurement of low-frequency sinusoidal signals with little or no frequency variation

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  • Frequency measuring method of alternating current signal
  • Frequency measuring method of alternating current signal
  • Frequency measuring method of alternating current signal

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Embodiment Construction

[0033] The technical scheme of the present invention is described in detail below in conjunction with accompanying drawing:

[0034] The essence of the present invention is to select several sampling points near the zero point, calculate the average value M and the average sampling occurrence time T of several sampling points, and then obtain T' according to the characteristics of the current signal and the average value M look-up table, by T+T ' to represent the zero-crossing point of the signal, so as to calculate the frequency or period of the signal. The selected sampling points should not be too many, if more sampling points are selected, the computational complexity will be higher; the selection of sampling points should not be too small, if the selected sampling points are less, it will be easily affected by interference. Therefore, users can select a reasonable combination and number of sampling points for calculation according to their needs.

[0035] In order to obt...

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Abstract

The invention provides a frequency measuring method of an alternating current signal. The method comprises the following steps of: sampling a tested electric signal; selecting a plurality of sampling points nearby a signal zero point according to a sampling value and calculating the average value of the sampling values of the plurality of sampling points and average sampling occurrence time; acquiring time by checking a table according to the characteristic of the current signal so as to represent the zero crossing point of the signal; and calculating the period or frequency of the tested signal according to the zero crossing point. By the method, the alternating current signal is not required to be converted into a square wave; the method is particularly suitable for measuring the frequency of a low-frequency sinusoidal signal at a fixed frequency, is convenient for system detection and has low hardware cost; a system has a certain anti-jamming capability; and the method is easy and reasonable to implement and correct and reliable data is obtained.

Description

technical field [0001] The invention relates to a method for measuring the frequency of an alternating current signal, which can also be used for frequency measurement of a low-frequency sinusoidal signal with a fixed frequency or little frequency change. Background technique [0002] In daily life and production process, it is often necessary to monitor the frequency of the signal. In the existing frequency measurement methods for low-frequency signals, the low-frequency signal is first formed into a square wave through a shaping circuit, and the time interval T between two adjacent rising or falling edges of the square wave is detected, and the frequency is obtained by calculating the reciprocal, but this The anti-interference ability of this method is poor. In addition, there are some methods for measuring frequency by software, such as: zero-crossing method, analytical method, error minimization principle algorithm, DFT algorithm, quadrature demodulation method, etc. S...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R23/02
Inventor 戴尔晗
Owner NANJING UNIV OF POSTS & TELECOMM
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