Demodulation Study Of Base-band Process In Communication System Of Pico-satellite

With the development of new technology, micro/nanosat will play an important part in research, national defense, and some business fields in the near future. Micro/nanosat not only can achieve significant reductions of satellite size, power consumption, and cut down the development cycle, but also can construct satellite cluster, sharing resource and information with each other. All these advantages enable them to accomplish more complicated space scientific experiments. Lying on the leading edge of micro/nanosat technology, picosat will have wide prospects.The progress of Micro-electronics and MEMS technologies brings along some key advancement to microsat research and also brings some change to its design conception. Three characters come out in micro/nanosat design: integrated design, modularization and software. Soft of the equipment and later being intellectualized will certainly be a key aspect of airspace researches in the future.The paper is discussed under pico-sat item. After building up an open and simple hardware-cored digital base-band platform, we carried out our research on the demodulation system of instruction of pico-sat. By analyzing the whole set of digital base-band process content, we try to find the open-up method of on-satellite processing, to find the way of soft-sat, and ultimately to achieve the goal of using updatable, re-collocatable software to realize kinds of function.Main work and features of this thesis are as follows:1. After modeling on the whole system and analyzing the potential trouble in the realization of DPSK demodulation, systemic analysis of method application are carried out on four aspects. Finally, results of simulation and field-test are given.2. Describe the realization of the whole system, both on software and hardware. Because McBSP is frequently used in our system and it is difficult to the selection of the McBSP working-mode, I give a detail discussion to this problem. At last, the debugging result in CCS is given.3. To evaluate the capability of the demodulation system, I build up a BER test platform based on our specification. The procedure help us know the whole system better and it is also a description of system-building. The BER test system will be used in thewhole system test.4. Sum up all the result of above, I conduct synthetical test for the system, including function test and BER test for the single board; function and BER test for the system coherent test; reliability test for the whole system.According to the content discussed above, base-band demodulation system had been realized on a piece of circuit board by the large of 9*4.5cm. From the result of synthetical test, it had passed single board and coherent test. It can work under the certain SNR and fulfill realtime processing. The whole power consumption is below 0.4w and static program utility-rate is 14.3%. There are much room left both for the hardware and software. It is a solid foundation for the update and soft-satellite.