Research On The Key Technologies Of Baseband Processing In Time Synchronization Between Satellite And Ground

The technology of time synchronization between satellite and ground is to realize time offset measurement and time synchronization between satellite clock and time on ground station by some kind of technical system, and this time synchronization between satellite and ground can adopt physical signal or model information to achieve synchronization. The technology of time synchronization between satellite and ground has a broad application value in established constellation time of satellite navigation system, precision time synchronization of space station, precision observe and control of satellite, missile's precision control, precise orbit determination and positioning of space vehicle and other fields.This thesis topic from West Light of The Chinese Academy of Sciences Project named “research on the methods of time synchronization between satellite and ground based on Ka link”. According to the research task of this topic, my subject mainly studies the methods and the implementation of baseband processing of the signal in time synchronization between satellite and the ground. First, this thesis introduces the development and importance of time synchronization between satellite and ground; second, it summarizes the principle and the merits and demerits of the several methods that current most commonly used to achieve time synchronization between satellite and ground; finally, it has worked on the production of ranging signal, research on the methods of acquisition and tracking, it also includes the design and implementation of acquisition and tracking based on FPGA and DSP. Specific studies as follows:1. To design the rate-compatible of pseudo-code and carrier, and to define the frame format of data. Realizing the generation of pseudo-code, carrier, data and ranging signal based on FPGA;2. To implement two methods of capture, including gliding correlation and folded matched filter, and achieve capture processing of received ranging signal;3. Studied the tracking method of ranging signal, realized the DLL code tracking loop and two order FLL assisted three order PLL of carrier tracking loop, completed the precision track of received ranging signal;4. To extract the pseudo-range, and calculated the real range and clock error.This thesis uses Altera EP2S180 FPGA and TI 6416 DSP to build the hardware platform, and achieves baseband digital signal process in time synchronization between satellite and the ground. In FPGA, it implements the of generation of ranging signal on the transmitter, signal acquisition, tracking, the bit synchronization and the frame synchronization on receiver, it also achieves the loop filter about code tracking loop and carrier tracking loop, range measurement, the calculated of real range and clock error in DSP. The test results show that the closed loop of baseband achieves the ranging accuracy of 0.8354 ns and the resolution of 7.4579 ps.