Research And Implementation Of CCSDS Adaptive Transmission System Based On FPGA

The aerospace industry of China has developed rapidly.The CCSDS standard is gradually adopted by China in the deep space exploration field.To transmit information with fixed rate under the environment of deep space communication,the communication quality and system efficiency will be affected.When the channel quality changes during the communication,adjusting the transmission parameters of the communication system in real time can improve the efficiency of communication system.According to the proximity-1 space communication protocols released by CCSDS,the establishment of an adaptive transmission wireless digital communication system is discussed in this paper,and it combined the characteristics of communication link transmission environment.This paper introduces the proximity-1 space communication protocols first.The performance index and the overall scheme and process of the system of the adaptive transmission protocol transceiver unit is researched and designed.Secondly,to realize the digital baseband signal processing and up conversion,the transmitter communication unit is designed.The realization scheme of PCM/PM modulation unit is verified by simulation analysis,and the pulse forming and matching filter for multi rate switching is also designed.Then,the realization scheme of digital intermediate frequency receiver is analyzed.On the basis of the analysis of the principle of orthogonal coherent demodulation,to introduce the Costas loop carrier synchronization algorithm.The carrier synchronization is realized with the FFT frequency offset estimation.The Gardner loop symbol synchronization algorithm gets the timing information by calculating the deviation of the best sampling point to achieve symbol synchronization.A kind of SNV and DF piecewise estimation method suitable for symbol rate adaptive transmission is proposed,by using SNR of the channel estimation as a standard for measuring the quality of the channel.Finally,the hardware circuit of the transmitter and receiver communication unit of the adaptive transmission system is designed and implemented.Through the test results of the system,it is proved that the adaptive transmission system designed in this paper is completed and reliable.