Measuring device and method for measuring relative phase shifts of digital signals

摘要

M periods of the test signal and of the reference signal are received. The periods of the test signal and of the reference signal are in each case T_sig long. The test signal is sampled with N sampled values at a sampling frequency f_s=1/T_s. Also, N*T_s=M*T_sig, where N>M. The sampled values are numbered progressively by n, for which 0<=n <=N-1. The sampled values have a defined relative phase shift with respect to the reference signal. The phase shift T_phi is calculated by $\sum _{i=0}^{M-1}\mathrm{Idx}\left(i\right)+K,$ K being a constant and Idx(i) corresponding to the number n which is either the first sampled value after a test signal zero crossing during the reference signal's i^th period or the last sampled value before a test signal zero crossing during the reference signal's i^th period. Either only rising or only falling zero crossings are taken into account.