Timebase distortion measurements using multiphase sinewaves

Distortions in the timebases of equivalent-time oscilloscopes and digitizers cause nonlinear distortions of waveforms sampled by them. This paper reports on a comparison of two methods of characterizing timebase distortion, using pure sinewave inputs of known frequency: the "sinefit" and the "analytic signal" methods. Simulations are used to compare the performance of the two methods versus different types of timebase distortion, different sinewave frequencies, number of different sinewave phases, levels of random noise, and levels of random jitter. The performance of the two methods varies considerably, dependent upon the input signal frequency and type of timebase distortion. Each method does much better than the other for certain cases.