Study On Group Delay Characteristics Of TDRSS Channel Based On Ground DBF

As a novel space-based tracking, telemetering and command system, Tracking and Data Relay Satellite System(TDRSS) represents a new direction in the international tracking, telemetering and command field. TDRSS plays an important role in increasing its coverage rate of the mediate/low orbit aircraft and decreasing the amount of ground telemetry stations in the satellite communication system. Therefore, it has a wide application prospect.TDRSS which consists of two geostationary satellites and one land terminal is a TT&C net, it covers several on-track aircrafts(satellite, spaceship, space station, etc.) and can deliver 300MBPS for the reverse link. As a lot of group delay distortion devices are on the reverse link, such as filters, mixers, power splitters, power amplifiers and so on which will make the high-speed data-transmission signal have group delay distortion and serious signal inter symbol interference, consequentially, the bit error rate increases. In this thesis, group delay distortion on the high-speed data signals is focused on, through fundamental research and simulation analysis, the degradation of system BER caused by linear and parabolic group delay are obtained, and adaptive equalization to compensate group delay distortion is proposed.The contents of this thesis include:1) Analyzed the Tracking and Data Relay Satellite System's reverse link scheme which is suitable for Chinese actual technical condition based on the American TDRSS design.2) Introduced the model of the reverse link, and analyzed the circuits which influence the performance of group delay, through theoretical analysis and simulation, it is proved that group delay distortion system satisfies band-pass equivalent theorem, that is, no matter where the group delay distortion is, impact of group delay distortion upon BER keep unaltered.3) Based on the band-pass equivalent theorem, some channel models of group delay distortion for simulation in MATLAB/SIMULINK are established. The BER performance and its connection with distortion system are shown in the result, which can provide references for project design and realization.4) Introduced solution for the distortion, then the probability of amending the distortion while using adaptive equalization are discussed before simulating some kinds of adaptive algorithms under group delay distortion channel. The results show that adaptive equalization can compensate group delay distortion effectively.Significant conclusions have been drawn for further study of TDRSS by analyzing the group delay distortion of TDRSS reverse link.