Effect of Recorder Time-Base Error on an AM-Baseband Telemetry System

A model of the demodulation portion of a suppressedcarrier AM-baseband telemetry system, incorporating the effect of tape recorder flutter, is developed. The carriers necessary for demodulation are derived from a single pilot by translation to the appropriate frequencies. The analysis illustrates how flutter affects system performance and shows that the effect is similar for both SSB and DSB systems. Minimization of error in the demodulated signal requires that filters in the data channels and the pilot channel have linear phase characteristics with identical slopes. The Appendix outlines the mathematical description of flutter for both predetection and postdetection recording and illustrates that the model is appropriate for analyzing both cases if the peak flutter is small.