Research Of Long Code Synchronous Technology In TDRSS

Tracking and Data Relay Satellite System(TDRSS), is a communication signal relay system which provides tracking and data acquisition services between low earth-orbiting spacecraft and ground control or data processing facilities.TDRSS represents a new direction in the international tracking telemetering and command field, and is an important symbol of the developing level of the spatial science in a country. The main tasks in this thesis focus on acquisition and tracking of pseudo random code for TDRSS, which is a part of digital receiver of TDRSS.A method based on short code leading long code is adopted in this paper, which makes use of the corresponding of phases of short code and long code .The short code is captured firstly, and then lead the long code through the captured short code. The simulation results show that this method reduces the search space and the acquisition time of the long code. Compared with traditional acquisition systems, the fast acquisition method adopted in this paper can get similar perfect performance with acceptable hardware spending.The thesis firstly introduces the form and development of TDRSS, gives the application of CDMA technique in TDRSS and summarizes the signal format in forward and backward link. And the theory of spread spectrum communication system and properties of m sequence and Gold sequence are offered. After that, we introduce some prevailing acquisition schemes such as the sliding correlation method and digital matched filter method, and compare the performance of the sliding correlation method with digital matched filter method. Lastly, the thesis offers the method and implement project by FPGA.