I have a signal made of a perturbed square wave, sampled so that there are at least six samples per period, for a total of 15 to 50 periods. The sampling frequency and the signal frequency are unrelated.
The perturbations are of several types:
jitter in the period (say 10%),
variable amplitude of the squares (say from 1 to 3),
additional arbitrary signal with an amplitude below 1, often localized.
I am looking for a simple, fast but robust computational procedure to estimate the average period (preferaby without a DFT or autocorrelation).