A MODEM FOR A DATA COMMUNICATION APPARATUS AND A DATA COMMUNICATION APPARATUS INCORPORATING SAID MODEM

摘要

PCT No. PCT/AU87/00280 Sec. 371 Date Apr. 21, 1989 Sec. 102(e) Date Apr. 21, 1989 PCT Filed Aug. 20, 1987 PCT Pub. No. WO88/01458 PCT Pub. Date Feb. 25, 1988.A modem (18) and data communication system (10) particularly for operation in high frequency (HF) media. The modem (18) comprises an audio period timer (52) to detect cycles of data from a received signal, a bandwidth window (62) to flag undefined cycles UD so as to prevent such cycles UD from further influencing decoding decisions, a bit rate timer (57) to predict ends of bits of byte formed from a plurality of said cycles, a bit rate synchronizer (76) to establish bit-wise synchronisation of the modem (18) with the received signal, a byte synchronizer to establish byte-wise synchronisation.