Comparison of time base nonlinearity measurement techniques

Distortions in the time bases of equivalent-time oscilloscopes and digitizers cause distortions of waveforms sampled by them. This paper reports on a comparison of two methods of characterizing time base distortion, using pure sine-wave 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 time base distortion, different sine-wave frequencies, number of different sine-wave 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 time base distortion. Each method does much better than the other for certain cases.