Time reference for measurements of arbitrarily shaped pulses

This paper addresses measurements of relative timing of irregularly and differently shaped pulses (by which we mean signals that are zero beyond a finite interval). For such pulses the usual time reference points become useless: rising edges may change their slopes and shapes, and maxima might split. We propose a definition of the time reference applicable to smooth but otherwise arbitrary pulses. It is applicable to signal scaling, simplifies the covariance matrix (of parameters´ error estimates) and yields an effective analytic estimate of timing error.