Skin Satellite Monitoring Answering Machine Phase-locked Loop Nested Structure

The Pico-satellite is an important research area in modern aerospace technologies. The development period, expense of micro-satellite is usually much lower than conventional satellites. The Pico-satellites can construct satellite cluster, sharing resource and information with each other. They can be used in three-dimensional imaging, distributed aerospace measuring, scientific experimentation at lower cost. The Pico-satellite will play ever more important role in military affairs, science research and commercial application with these advantages.The research on MEMS Pico-satellite in our research group began four years ago. Before my research, the satellite has realized initial communicating function with carrier wave. My major contribution to the satellite during my master period includes two parts. On the one hand, I optimized the TT&C transponder's performance and achieved the integration of the whole Pico-satellite system. On the other hand, the model of the nested-loop PLL, which is the most important component in the TT&C transponder, is established based on the modern charge-pump PLL. The lock time and phase noise characteristics are simulated, and the results are similar with the test results of real circuit. After analyzing the results of the simulation, the TT&C transponder's performance has been optimized.Main features of this paper are as follows:1. After analyzing the modern charge-pump PLL thoroughly, I simulate the lock time, phase noise and RMS phase error characteristics by matlab. The results of simulation are consistent with the results tested by actual circuit.2. I establish the model of the nested-loop PLL based on modern charge-pump PLL. The lock time and phase noise characteristics are simulated, and the results are similar with the test results by actual circuit. I improved the actual circuits by the results of the simulation, and improved TT&C transponder's performance.3. A method to design a single PLL circuit is introduced. I simplified the method and improved its accuracy by numerical calculation method. Then I can design thenested-loop PLL combined with the method to analyze the nested-loop PLL.4. The LNA and AGC are two important modules in the TT&C transponder circuit. I bring forward a method to minimize the noise figure of the whole transponder with the help of ADS. I also obtained the AGC expression by fitting the test curves in order to deepen my understanding of the AGC module.5. All test items about TT&C transponder have met the design spec. The Pico-satellite passed the reliability experiments including temperature circulation experiment, vibration experiment and particle radialization experiment. The whole Pico-satellite system realized all functions in the wireless transmission test. Based on research and experiments, the performance of the S-band TT&Ctransponder of satellite is improved in the following dimensions: has sensitivity up to -92dBm; dynamic range wider than 55dB; capture bandwidth of the receiver wider than 500KHz; capture time reduced to 5.4ms. The Pico-satellite has passed the reliability experiments, too. In the wireless transmission test, the satellite can collect the information from CMOS camera and the sensors according the corresponding commands. After receiving the signal from satellite, the earth station can demodulate it and recover the image and sensor curve. All these results indicate that the S-band TT&C transponder we developed reach the design specification and even outperform it and basically meet engineering requirements.