Development of a concatenated Reed-Solomon/Viterbi FEC combined modem and its field test via 14/11 GHz satellite

The development of a concatenated FEC (forward error correction) codec and its associating PSK (phase shift keying) modem aimed at low-bit-rate satellite communications use are discussed, and their performance in a field test at the 14-GHz/11-GHz band using an INTELSAT-V satellite is assessed. The FEC codec consists of a convolutional encoder with a Viterbi decoder for inner coding and a Reed-Solomon encoder with a Euclid decoder for outer coding. A coding gain of 7.5 dB was achieved at a bit error rate (BER) of 10^-6 relative to the uncoded performance, and virtually error-free transmission was achieved at a carrier/noise (C/N) ratio of 0 dB. Some tests were conducted to transmit a voice signal and G3- and G4-facsimile signals, which revealed that the qualities of both received facsimile signals were highly dependent on the event error probabilities rather than the BERs. It is concluded that the developed FEC combined modem is useful for reliable data transmission in the low C/N ratio environment