Synchronization For Continuous Signals In Code Division Multiplexing Link

Ground Based Beamforming(GBBF) offers great advantages in terms of expansibility and flexibility compared with traditional Digital Beamforming(DBF). Hence, GBBF has been attracting increasing research attention in recent years. In the Code Division Multiplexing(CDM) feeder link of GBBF, the transmission signals are continuous signals, which require high-performance synchronization technology. Based on the situation, this paper researched the synchronization of CDM feeder link of GBBF.For the carrier synchronization, we firstly analyzed the requirement of the link and drawn a conclusion that method of carrier synchronization of the link must be a closed loop synchronous circuit with pilot-assisted, and the circuit needs Frequency Lock Loop(FLL) assist to improve accuracy of carrier synchronization. Then the paper compared prevalent pilot and closed-loop carrier synchronization methods, and drawn a conclusion that parallel pilot and Decision feedback loop(DFPLL) are the best for the link. Finally, the paper researched the structure of FLL aided DFPLL and demonstrate the performance superiority by simulation.For the timing synchronization, this paper offered two methods by analyzing feature of CDM feeder link of GBBF, either take the system to be a spread frequency system or not. The paper also provided two ways for timing synchronization for spread frequency system, but the performance of the two ways are unsatisfactory. Therefore, this paper take the system as a non-frequency system and put forward a new bit synchronization algorithm, which solve the key point of timing synchronization. We gave deduction and design of the algorithm in detail, and showed performance by simulation.For the FPGA design of synchronization algorithms, the paper researched the difficulty of the design and gave the solutions, and offered the hardware simulation and test scheme at the end.