The Detection of PCM/FM

Abstract

The calculation of the error rate resulting from the detection of PCM/FM is described. Emphasis is placed on characterizing the effect of the FM demodulator (FMD). The works of Schilling(l), Salz(2), and Klapper(3), are summarized and extended to yield error rate expressions when using an FM discriminator, Phase Locked Loop, or Frequency Demodulator Using Feedback (FCF). The "Integrate-and-Dump" and the Filter Detector are compared. The results indicate that in certain regions the error rate is due primarily to "smooth noise", and the FM demodulator followed by a PCM detector yields an error rate comparable to that obtained with a Matched-Filter (MF) detector. In other regions the error rate is shown to be due primarily to the spikes present at the FM demodulator output. The use of "Spike Detection and Correction" is discussed. It is shown that this technique results in reduced error rate in the "spike regions".