采用微弱信号进行定位是当今研究的一个热点,这一技术的实现基于对弱信号的成功捕获。加长相干积分时间和非相干累加次数是实现微弱信号捕获的基本原理。针对北斗MEO/IGSO卫星因存在NH码二次调制而导致使用GPS捕获方法捕获灵敏度降低的...采用微弱信号进行定位是当今研究的一个热点,这一技术的实现基于对弱信号的成功捕获。加长相干积分时间和非相干累加次数是实现微弱信号捕获的基本原理。针对北斗MEO/IGSO卫星因存在NH码二次调制而导致使用GPS捕获方法捕获灵敏度降低的问题,提出了串行剥离NH码加半比特积分方法。基于FPGA+DSP实现对北斗微弱信号进行捕获的方法,在保证捕获灵敏度的同时,控制捕获时间。测试结果表明,该算法可实现-142 d Bm信噪比条件下的北斗弱信号捕获,并可进一步提高卫星导航接收机灵敏度。展开更多
According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the ...According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the phase of Pseudo-Noise-code(PN-code),Doppler frequency and its rate-of-change is presented to achieve high sensitivity in sensing high-frequency dynamics. By eliminating the correlation peak loss caused by ultrahigh Doppler frequency and its rate-of-change offset,the proposed method improves the acquisition sensitivity by increasing the non-coherent accumulation time. The validity of the algorithm is proved by theoretical analysis and simulation results. It is shown that signals with a carrier- to-noise ratio as low as 39 dBHz can be captured with high performance when the Doppler frequency is up to ±1 MHz and its rate-of-change is up to ±200 kHz/s.展开更多
文摘采用微弱信号进行定位是当今研究的一个热点,这一技术的实现基于对弱信号的成功捕获。加长相干积分时间和非相干累加次数是实现微弱信号捕获的基本原理。针对北斗MEO/IGSO卫星因存在NH码二次调制而导致使用GPS捕获方法捕获灵敏度降低的问题,提出了串行剥离NH码加半比特积分方法。基于FPGA+DSP实现对北斗微弱信号进行捕获的方法,在保证捕获灵敏度的同时,控制捕获时间。测试结果表明,该算法可实现-142 d Bm信噪比条件下的北斗弱信号捕获,并可进一步提高卫星导航接收机灵敏度。
基金supported by the Youth Science Fund,National Natural Science Foundation of China under Grant No.61102130
文摘According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the phase of Pseudo-Noise-code(PN-code),Doppler frequency and its rate-of-change is presented to achieve high sensitivity in sensing high-frequency dynamics. By eliminating the correlation peak loss caused by ultrahigh Doppler frequency and its rate-of-change offset,the proposed method improves the acquisition sensitivity by increasing the non-coherent accumulation time. The validity of the algorithm is proved by theoretical analysis and simulation results. It is shown that signals with a carrier- to-noise ratio as low as 39 dBHz can be captured with high performance when the Doppler frequency is up to ±1 MHz and its rate-of-change is up to ±200 kHz/s.
