Signal frequency measuring method based on period tracking method and mobile integer period method

Abstract

The invention discloses a signal frequency measuring method based on a period tracking method and a mobile integer period method. The signal frequency measuring method comprises the specific steps that first, the timer frequency f[clk] and an allowed measuring error epsilon are set; second, if the upper limit f[max] of a measured signal frequency f is unknown, the mobile integer period method is used for measuring the signal frequency, and if the upper limit f[max] of a measured signal frequency f is known, whether the f[max], the f[clk] and the epsilon meet the relational expression that f[max] is smaller than f[clk]*epsilon is judged, if yes, the period tracking method is used for measuring the signal frequency, and if not, the mobile integer period method is used for measuring the signal frequency. The period tracking method can update the measuring result in time when detecting the situation that the signal period is prolonged, and the mobile integer period method achieves the effect that the measuring result is updated at least one time in each signal period. The period tracking method and the mobile integer period method can track the changing process of the signal frequency faster, the hysteresis error is reduced, the requested number of timers is not increased, the calculation amount is small, only a small amount of memory variable needs to be added, and therefore the hardware cost of a frequency testing device 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 test and control system, the frequency signal input to the microcontroller or data acquisition card is a conditioned square wave signal. Commonly used frequency measurement methods include cycle measurement method, integer cycle method and frequency measurement method. These measurement methods suffer from hysteresis errors when the signal frequency changes, and the faster the signal frequency changes, the greater the error. In practical applications, since the timer frequency of the current single-chip microcomputer and data acquisition card is usually tens of MHz, except for the communication signal, the signal frequency of most test and control systems is lower than 100KHz, which is far lower than the timer frequency. Measured by week method and integer period method. [0003...

AI Technical Summary

Problems solved by technology

Example: timer frequency f clk is 10MHz, if the square wave signal frequency f is 120kHz, But since i is a count value, it can only be an integer, so in the actual test, i may be 83 or 84

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