Digital terrestrial television transmission over OFDM/FM using satellite communications system

The new digital terrestrial television transmission signals use the OFDM system. This system has the fundamental problem that the peak power to average power ratio (PAPR) of the signal is significant. In this paper, a satellite communication system is proposed as a supplemental network for digital terrestrial broadcasting. It is shown that effective use of the satellite power becomes possible at a large PAPR by using the FM system with a constant signal envelope as the secondary modulation, so that the problem can be resolved. It is shown analytically that a larger FM gain can be obtained by limiting the peak voltage of the OFDM signal by clipping. The degradation of the BER caused by clipping is derived by simulation and the system is optimized with regard to the degree of clipping. Taking the size and operational cost of the receiving station into account, channel design is performed assuming a real satellite channel. The overall transmission characteristics such as the transmission capacity of the satellite repeater and the channel quality are discussed