1. An apparatus for analyzing time variable electrical signals comprising: (a) first means for generating a time variable electrical analog signal, (b) second means for receiving and analyzing said analog signal, (c) said second means including means for separating those portions of the analog signal having characteristics varying beyond a predetermined minimum value and for selectively gating said separate signal portions to said receiving and analyzing means, (d) said analyzing means including means responsive to variations in said separated signal portions for digitizing same, and (e) said digitizing means including means for generating a plurality of digital code signals which are indicative of the value of the variations in said electrical analog signal.