Signal frequency real-time measuring method based on low-frequency square signal frequency prediction

Abstract

A signal frequency real-time measuring method based on low-frequency square signal frequency prediction comprises the steps that (1) tested square signals are obtained; (2) the initial moment and the time width of the square signals are measured and recorded; (3) a linear fitting prediction method or a quadratic fitting prediction method is used, and a frequency linear fitting formula or a frequency quadratic fitting formula of tested signals is obtained; (4) prediction frequency is computed in real time and output; and (5) whether new signals are obtained is judged, if yes, the step (2) is carried out, and otherwise the step (4) is carried out. Prediction values are used for replacing measuring values to be used as output values, the prediction values can compensate the hysteresis errors existing in the measuring values, accordingly, the accuracy of real-time frequency measuring is improved, the measuring accuracy of steady state frequency is not lowered, an extra timer is not occupied, computing quantity is small, and meanwhile the hardware cost of frequency testing equipment cannot be increased.

Description

technical field [0001] The invention relates to the technical field of signal testing, in particular to a method for real-time measurement of signal frequency. Background technique [0002] In the frequency measurement equipment, the signal is measured by sensor sensing, conditioning circuit shaping, processor acquisition and calculation, etc., because each link takes time, so the measured value lags behind the actual value in time, when the actual frequency is constantly changing When , the measured value will produce a lag error due to the time lag. Current frequency measurement equipment such as frequency testers and tachometers use the measured value as the output value, so there is also a hysteresis error. [0003] The timer clock frequency of the current single-chip microcomputer and data acquisition card is usually tens of MHz. Except for the communication field, in most control systems, the measured signal is a square wave signal with a frequency lower than 100KHz. ...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to propose a more real-time and accurate method for measuring the frequency of low-frequency square wave signals, which can compensate for the hysteresis error existing in the existing cycle measurement method, and can be used for equipment with low-frequency signal frequency measurement functions such as frequency meters and tachometers.

Images