| A BOC(Binary Offset Carrier) modulation signal generator for regional satellite navigation system is studied and implemented in this paper, which generates BOC modulated signals and spreading signals including C/A code and P code, modulates them separately by BPSK with variable gain, and compounds them into a new signal as an output. With development of PLD, SOPC technology based on FPGA appeared. And for its parallel features and programmability, FPGA is selected as an ideal platform for implementing signal generation.Based on theory analysis, modeling and simulation, introducing FPGA development technology, a scheme to implement the system in a single FPGA chip is proposed, including generating the signals, BPSK modulating and compounding these signals. As working frequency is exact multiples of a certain frequency, a method to make all generated signals synchronous is introduced in detail for this multi-rate system, by using synchronization circuits with a global clock whose frequency is a common multiple of the overall working frequency.The scheme is realized on DSP Development KIT Stratix II EP2S60 and tested by SignalTap II and spectrum analyzer, which verifies the validity of the scheme. |
