PERFORMANCE OF TONE CALIBRATION WITH FREQUENCY OFFSET AND IMPERFECT PILOT FILTER

Recent years have seen a renewal of interest in the pilot tone as a way to obtain a phase reference for demodulation on rapidly fading channels. The principal virtue of tone calibrated transmission (TCT) is that it suppresses the irreducible error rate, or error floor, encountered in coherent and differentially coherent detection. This paper presents a relatively complete analytical treatment of TCT error rate. It includes the effects of Rice and Rayleigh fading, frequency offsets, and a selection of nonidealities in the receiver's pilot tone filter. Such nonidealities are shown to result in the reappearance of an error floor, which we quantify and show to be insignificant except for extreme fading rates. Comparison with differentially detected PSK shows that TCT provides a lower BER in the noise limited region, and a much lower (by orders of magnitude) error floor in the random FM limited region.