Reception Performance Of Single Frequency Network Of Terrestrial Digital TV Broadcasting Based On RF Sychronization

Currently, terrestrial digital TV single frequency network(SFN), which based on multi-carrier modulation, utilizes the baseband stream allocation to ensure the reliability of data reception, but modulation discrete between base stations and the multipath delay, which is longer than the guard interval of OFDM, easily cause self-interference. This paper proposes RFST technology, aiming at avoiding the differences in delay time, frequency and phase, which can cause self-interference, because of the baseband stream allocation that the way different RF signals transmit, and modifying multipath problems.First, according to the basic principle and key technologies of SFN system, the existing terrestrial DTV SFN commonly use baseband synchronous networking. This paper proposes RFST technology which allocates the only modulated RF signal to each base station, and transmits the RF signal on identical frequency after synchronization delay processing. Then analyses of theoretical basis and practical application show the guarantee of spectrum characteristic. Finally, a Matlab transimition model of terrestrial DTV signal in SFN uses a typical Gaussian, Rayleigh and Rice channel to analysis the system performance on the impact of modulation discrete. The results show the value of bit error rate(BER), which is 310?, needs 0.2dB improvement of modulation error ratio(MER). When MER degrades 0.1dB, BER will raises 0.1dB and the value of ?MER is bigger, the increase speed is higher.The results show that the use of RFST ensures consistent spectral characteristics of the RF signal and the reducation of BER. It avoids interferences in the same channel and improves the system performance. The advantages on self-interference, network construction cost, weaken dependence on GPS devices and so on, provides a better performance networking for the middle or small area coverage.