光栅信号微机细分的分辨率和精度分析

本文介绍了利用正、余弦信号的正交性进行光栅信号微机细分的原理,给出了采样点的相角计算公式,提出并设计了一种用于光栅信号峰、谷值采样的峰、谷值保持电路,避免了通常在利用正、余弦信号的正交性进行峰、谷值采样时因正交性差而带来的误差。此外,还介绍了在软件上校正正、余弦信号正交性对测量精度影响的方法。分析表明:采用八位模数转换器时该方法的分辨率和精度分别可达光栅周期的0.2%和0.5%.

ANALYSIS OF DISTINGUISHABILITY AND ACCURACY OF SUBDIVIDING GRATING SIGNAL BASED ON MICROCOMPUTER

The paper introduces the principle of subdividing grating signal based on microcomputer by means of the orthogonality between sine and cosine signal,and gives the formulae for calculating the phase of sample points. In the paper,a new kind of peak/valley holder circuit is put forward and designed to eliminate the errors of gathered peak and valley value caused by the orthogonality errors in the ordinary way.The method of rectifying the influence of the orthogonality on measurement by software is provided, too. The results have proved that the distinguishability of 0.002T(T refers to the period of the grating.)and the accuracy of 0.005T can be achieved by using the method discussed and a 8-bit ADC.