High Rate Data Transmission System for Space Solar Telescope

The Space Solar Telescope (SST) is a very important astronomical satellite project in China. It will carry on five observing instruments and the main optical telescope with the aperture of 1m to observe simultaneously in different wave bands for the white light, UV light, hard X-ray, soft X-ray, Hα line and radio emission etc. The quantity of the scientific data collected by CCDs and other sensors of the five payloads every day will reach 50 Gbtes. The huge data will be then compressed to about 8 Gbtes by a data compression system and saved in a memory system.Hence it needs to transmit the scientific data down to the satellite ground station at a bit rate of 60Mbps within about 43minutes. In this paper, a high rate scientific data transmission system (DTS) is introduced as follows: Firstly, the DTS is designed and its characteristics are studied and analyzed comprehensively according to the requirements of the SST. Secondly, the Channel Encoding-Decoding unit of the DTS is designed and developed. The Channel Encoding unit will be used to translate the parallel data stored in the memory into two streams of serial formatted data, which are fit for QPSK radio modulation, and the Channel Decoding unit will be used to realize the reversed processes. Some new ideas of communication system are included in the design. And the protocol of this system is completely compatible with that of the existent satellite ground station. Thirdly, ground experiments on the base-band link system of the Channel Encoding-Decoding unit are made. As results, the specifications of the Channel Encoding-Decoding unit have perfectly fulfilled the requirements of the SST, among which no error exists in ideal no-noise situation and the data rate has reached 60Mbps-the highest data transmission rate at present in the satellite scientific data transmission systems in China. Fourthly,the software simulation is an important process to guarantee the scheme design. Several simulations on methods, principles and hardware design are given. At last, the principle, method and laboratory test results of developing the Channel Encoding-Decoding unit are also given in details in the paper.