A new carrier recovery circuit for mobile satellite communications

Abstract

A reverse modulation carrier recovery circuit for coherent detection of QPSK signals in Rician fading channels is proposed. The scheme consists of two reverse modulation type carrier recovery circuits, one of which has a wideband filter and the other a narrowband filter. The forward error correction (FEC) decoded data is used to reverse-modulate the received signals for the carrier recovery circuit, with a wideband filter, to achieve a low carrier skipping rate and a good phase tracking performance. It is clarified by computer simulation that the P/sub e/ (bit error probability) performance of QPSK coherent detection using the proposed carrier recovery circuit show an E/sub s//N/sub 0/ improvement of 4.0 Db without interleaving, and 1.2 dB with interleaving (size 64*64) at P/sub e/=10/sup -4/ (C/M=10 dB; f/sub D/T=1.67*10/sup -2/) compared with conventional coherent detection employing the reverse modulation tank-limiter scheme.<>