| As a new generation of micro-satellite based on micro-electro-mechanic system (MEMS), Pico-satellite, in virtue of its low weight (1kg or lighter), is unburdened from high-cost large sending sets. Thereby research of Pico-satellite can be progressed with much lower cost without huge experimental establishments and wide-span workshops so that institutions, mostly universities, became the main researching force. Besides reduced expenses, another advantage of research in university laboratories is the potential high privacy.Limited by its small volume and power consumption, Pico-satellite can only be sole-functional. But it could still meet different flight missions if a standard platform were developed for various effective loads coupled with Pico-satellite's specialty of satellite cluster sending with single rocket. Therefore, to develop a standard Pico-satellite central system and applied platform has been a prerequisite to put Pico-satellite into full use in scientific and commercial affairs.Before my research, it has been three years that research on MEMS Pico-satellite is carried about in our research center. Since Pico-satellite could already basically communicate with carrier wave, my major approach is to optimize the communicator's performance, to process the follow-up connect and charactization after data modulation, to present primary reliability design and simulation so as for the whole system to satisfy engineering needs. Main features of my paper are as follows:1.Taking advantage of (Advance Design System)ADS, one of the most powerful radio-frequency simulation tools, we mean to simulate and design lower-noise-amplifier(LNA) for lowest noise coefficient and maximum gain as preparation for systematic simulation.2.As for the intermediate frequency part in integrated circuits (IC's), we introduce feedback automatic gain control(AGC) loop in view of its fargoing dynamicrange and convenient precision adjustment, hence stable power of fore-demodulator signal and maximum systematic gain are ensured.3.With comprehensive improvement of transponder including structural adjustment to LNA; optimization of (phase locked loop)PLL filter; structural adjustment to the transmitter and phase error adjustment to the intermediate frequency demodulation circuit, we have successfully enhanced sensitivity, expanded dynamic range , increased transmitting power and improved the spectrum purity; decreased capture time for PLL; improved the signal quality after demodulation; reduced its volume and power consumption.4. Besides TT&C transponder, the power support for Pico-satellite also covers CMOS camera, data processing unit and energy subsystem, by connecting and charactization which, full course from modulation and demodulation of instruction data to feedback of image data, wireless long-range transmission and the feedback of sidetone signal could be achieved.5. We present reliability design specially electromagnetic compatibility design, and related theories for the system as foundation for further reliability experiments.Based on research and experiments, we effectively improved the S-band TT&C transponder for satellite in such dimensions: with sensitivity up to -92dBm; dynamic range wider than 55dB; capture bandwidth of the receiver wider than 500KHz; capture time reduced to 22ms. Other success involves better image reproduction on computer of the pictures taken by satellite-loaded CMOS camera and this is achieved by wireless transmission with S-Band TT&C transponder and reception with our self-made earth station. All these results indicate that the S-band TT&C transponder we developed reach the design expectation or even outdo and can basically satisfy engineering requirements.
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