Abstract: System for analyzing a signal waveform includes a periodicity analyzer for detecting the time of occurrence of individual repetitions of a predetermined type within a periodic event in the signal waveform. The periodicity analyzer can provide, in response to this event being periodic, a periodicity signal corresponding to the period of the predetermined periodic event. Also included is a residue analyzer for providing upon the occurrence of a predetermined feature of the signal waveform, a normalized signal bearing a predetermined relation to the signal waveform. The apparatus also includes a utilization subsystem coupled to the periodicity analyzer and residue analyzer for providing an output signal based upon the contemporaneous values of the normalized signal and the periodicity signal.