Fixed-lag demodulation of discrete noisy measurements of FM signals

This paper considers an application of some recent results of fixed-lag smoothing algorithms to the demodulation of discrete noisy measurements of FM signals. The problem is attacked by first modelling the communications system in terms of a finite dimensional nonlinear stochastic system and relating the resulting model to an estimation problem for which approximate solutions can be obtained. Performance results are presented, using the modified truncated second order filtering algorithm. The results illustrate that if delay is allowed in arriving at an ''on-line'' optimum estimate, significant improvement can be obtained by even a very moderate fixed-lag.