The effects of bandpass limiters on nphase tracking systems
Abstract
The combination of a bandpass limiter and an n(th) power tracking loop is considered. It is shown that the performance of the combination does not depend on the form of the nonlinear function used to create the n(th) harmonic signal so long as some energy in that zone is produced. Furthermore, the order in which the limiter and n(th) power nonlinearity occur is unimportant so that the results apply equally well to the nphase Costas type of implementation of the n(th) power loops. Closed form expressions for the signal suppression factors are obtained and it is shown that the coherent and noncoherent SNR's out of the n(th) powerlimiter combination can be expressed in terms of two of these suppression factors. This later point enables one to estimate the loop SNR of an n(th) powerlimiter phase locked loop by simply calculating the suppression factors for n(th) and 2n(th) power loops. Finally, n(th) power phase locked loops without limiters are compared with similar loops with limiters where it is shown that the presence of the limiter can actually enhance the output SNR at moderate to large values of input SNR.
 Publication:

International Conference on Communications, Volume 2
 Pub Date:
 1977
 Bibcode:
 1977icc.....2...21B
 Keywords:

 Bandpass Filters;
 Limiter Circuits;
 Phase Locked Systems;
 Signal To Noise Ratios;
 Tracking Filters;
 Feedback Control;
 Performance Prediction;
 Signal Transmission;
 Transmission Efficiency;
 Electronics and Electrical Engineering