A Suitable Combination of Modulation and FEC Schemes for Satellite Digital Video Communication Networks

Shuji KUBOTA  Masahiro MORIKURA  Kiyoshi ENOMOTO  Shuzo KATO  

IEICE TRANSACTIONS on Communications   Vol.E76-B    No.5    pp.497-507
Publication Date: 1993/05/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Satellite Communications Networking and Applications)
satellite communication,  modulation,  FEC,  digital video communication,  

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This paper proposes a suitable combination of the digital modulation schemes and the coding-rate of forward error correction (FEC) schemes for satellite digital video communication networks. The comparative study is carried out by computer simulation considering non-linearly amplified, narrow bandwidth satellite channels with adjacent channel interference signals. The proposed system employs an offset QPSK modulation scheme supported by the coding-rate of 7/8 convolutional encoding and Viterbi decoding to realize high-quality and compact spectrum characteristics in non-linear channels. By employing a 32Mbps DPCM video codec, the developed prototype system achieves a post demodulated S/N ratio of higher than 52dB. Moreover, it achieves high protection ratio against co-channel interference than conventional analog FM systems. The optimized digital video transmission system makes it possible to transmit high-quality NTSC video signals over non-linearly amplified narrow bandwidth satellite channels, for example 27MHz or 36MHz bandwidth transponders, with high-security digital encryption.