针对微弱信号环境卫星导航定位系统信号捕获概率低的问题,提出多个码元累积提高信噪比的捕获算法.该算法以部分匹配滤波器结合快速傅里叶变换相干累积(Partial Matched Filtering based on Fast Fourier Transform,PMF-FFT)单元为基础,...针对微弱信号环境卫星导航定位系统信号捕获概率低的问题,提出多个码元累积提高信噪比的捕获算法.该算法以部分匹配滤波器结合快速傅里叶变换相干累积(Partial Matched Filtering based on Fast Fourier Transform,PMF-FFT)单元为基础,通过复用实现多码元相干累积和非相干累积,获得了更长的码相干时间和更大的非相干累积增益,提高了捕获灵敏度,缩短了捕获时间,提高了抗干扰能力.仿真结果表明,该算法能明显提高系统捕获性能,在相同信噪比条件下,较普通PMF-FFT算法在捕获概率上提高约4dB,可应用于我国北斗二代卫星导航系统.展开更多
As the raised cosine shaping filter is often employed in practical satellite communication system,the envelope fluctuation at the symbol transition point is decreased which leads to the failure of the common wavelet a...As the raised cosine shaping filter is often employed in practical satellite communication system,the envelope fluctuation at the symbol transition point is decreased which leads to the failure of the common wavelet algorithm under low SNR.Accordingly,a method of blind symbol rate estimation using signal preprocessing and Haar wavelet is proposed in this paper.Firstly,the effect of filter shaping can be reduced by the signal preprocessing.Then,the optimal scale factor is searched and the signal is processed and analyzed by the Haar wavelet transform.Finally,the symbol rate line is extracted and a nonlinear filter method is inducted for improving the estimation performance.Theoretical analysis and computer simulation show the efficiency of the proposed algorithm under low SNR and small roll-off factor.展开更多
文摘针对微弱信号环境卫星导航定位系统信号捕获概率低的问题,提出多个码元累积提高信噪比的捕获算法.该算法以部分匹配滤波器结合快速傅里叶变换相干累积(Partial Matched Filtering based on Fast Fourier Transform,PMF-FFT)单元为基础,通过复用实现多码元相干累积和非相干累积,获得了更长的码相干时间和更大的非相干累积增益,提高了捕获灵敏度,缩短了捕获时间,提高了抗干扰能力.仿真结果表明,该算法能明显提高系统捕获性能,在相同信噪比条件下,较普通PMF-FFT算法在捕获概率上提高约4dB,可应用于我国北斗二代卫星导航系统.
基金Supported by the National Natural Science Foundation of China (No. 60972061,60972062,and 61032004)the National High Technology Research and Development Program of China ("863" Program) (No. 2008AA12A204)the Natural Science Foundation of Jiangsu Province(No. BK2009060)
文摘As the raised cosine shaping filter is often employed in practical satellite communication system,the envelope fluctuation at the symbol transition point is decreased which leads to the failure of the common wavelet algorithm under low SNR.Accordingly,a method of blind symbol rate estimation using signal preprocessing and Haar wavelet is proposed in this paper.Firstly,the effect of filter shaping can be reduced by the signal preprocessing.Then,the optimal scale factor is searched and the signal is processed and analyzed by the Haar wavelet transform.Finally,the symbol rate line is extracted and a nonlinear filter method is inducted for improving the estimation performance.Theoretical analysis and computer simulation show the efficiency of the proposed algorithm under low SNR and small roll-off factor.
