Study And Implementation On Key Technology Of The Baseband Signal Processing System Of TDRSS

This dissertation studies the the Baseband signal Processing System of TDRSS,which is a submodule of the receiving system of the forward link of the TDRSS.As a novel space-based tracking, telemetering and command system, the Tracking and Data Relay Satellite System (TDRSS) represents a new direction in the international tracking telemetering and command field. The SNR of the Baseband signal Processing System of TDRSS is–20dB and the doppler shift is±100kHz ,in which UQPSK modulation and direct sequence spread spectrum(DS-SS) are employed. As a result,how to achieve fast acquisition of the PN code and the Baseband Compensation of the severe doppler shift become the key issue in the study.First of all,this dissertation analyzes the key issue of the system in detail, study the application of Digital Match Filter (DMF) in PN code synchronization against the disadvantage of slippage correlation acquisition.,and analyze how to achieve DMF on FPGA efficiently.For the severe doppler shift,discuss the frequency shift acquisition an tracking algorithm, present the application structure diagram,and use the DMF to assist the AFC loop to achieve the initial acquisition fast and accurately.The baseband system which is mentioned in this paper is based on FPGA, so the design and implementation of the system scheme on FPGA is also a key point.The algorithm is optimized according to the characteristic of FPGA.The system scheme which is mentioned in the dissertation is applied in an advanced development prototype successfully.It works well.And more details will be optimized and improved in practice.