| 摘要 |
The present invention concerns a method and an apparatus for differentially coherent reception in Offset Differential QPSK (ODQPSK) signaling and some Continuous Phase Modulation (CPM) signaling schemes. The method is operative in a receiver structure which is essentially characterised by one of two alternative types of differentially coherent demodulator followed by a two-input recursive computation means responsible for the simultaneous soft differential decoding and channel equalisation. One demodulator type involves correlation of the received intermediate frequency signal with two delayed versions of it, wherein the delay times differ by a half transmission bit period and low pass filtering. The second demodulator type involves successive down-conversion of the received intermediate frequency signal by using a free running local oscillator; matched filtering, phase extraction, phase differentiation and differential phase delaying by a half transmission bit period. The invention more particularly applies to wireless local loop, to satellite links, and to mobile radio communications. |
