On the Threshold Effect in FM Data Systems
Mark Malone · IRE Transactions on Communications Systems · 1966
The threshold noise performance of a limiter-discriminator, with input signal uniformly distributed over the full scale frequency deviation range, is analyzed in terms of an evaluation criterion which specifies the system resolution(\pm R)and the probability (P) with which output noise exceeds that resolution. This criterion, meaningful above and below threshold, forms a basis for a precise definition of threshold, the location of which is determined equally precisely and found to lie between 6 dB and 10 dB input signal-to-noise ratio (SNR) for the range of (R, P) values considered. The channel efficiency of FM relative to Shannon's law is also determined approximately in light of this criterion, from which the ultimate FM threshold follows.