应用频率误差修正的高灵敏度GPS信号捕获技术  

A highly sensitive GPS signal acquisition technique using frequency error correction

作　　者：丁继成[1] 赵琳[1] 余小辉[1] 

机构地区：[1]哈尔滨工程大学自动化学院,黑龙江哈尔滨150001

出　　处：《哈尔滨工程大学学报》2009年第8期887-892,共6页Journal of Harbin Engineering University

基　　金：国家自然科学基金资助项目(60474046)

摘　　要：为提高弱信号环境下GPS捕获的灵敏度和频率精度,分析了差分相干捕获的输出特性,并对捕获频率误差的分布性进行理论推导.在此基础上提出在捕获过程中将频率误差修正值通过反馈环路实时引入本地振荡器,使修正后的sinc项趋近于1.理论分析与性能评估结果表明,差分相干输出近似服从高斯分布,提出的方案在处理低信噪比的GPS信号时,灵敏度优于非相干法2 dB、标准差分法0.5 dB;在给定的积分时间下,捕获得到的多普勒频率均值与实际值的误差小于5 Hz,标准差小于20 Hz,而且具有捕获频率精度随积分时间增加而提高的优点,能够满足后续弱信号跟踪要求.To enhance GPS signal acquisition sensitivity and frequency precision in a weak signal environment, a differential coherent signal acquisition technique was evolved. Distribution of frequency errors caused by signal acquisition was analyzed in detail. On this basis, a frequency error correction acquisition method was put forward. This method makes local carrier and code oscillator frequency corrections through a frequency error feedback loop. It is theoretically able to make converge to one. The analysis and testing results validated that when processing GPS signals with low SNR, the modified differential acquisition scheme enhances sensitivity 2dB more than non-coherent techniques and 0.5dB more than the differential coherent method. Given the time of the integral, the mean error of the Doppler frequency is less than 5Hz, and standard error is less than 20Hz. Most important, the acquisition frequency precision increases with prolongation of the integral time, satisfying requirements of the next step in tracking weak GPS signals. These results are ideal for tracking weak GPS signals.

关 键 词：GPS 灵敏度 差分相干捕获 频率误差修正 

分 类 号：TP391.9[自动化与计算机技术—计算机应用技术]