GPS 接收机伪码捕获自适应判决门限估计算法

刘娣; 薄煜明; 邹卫军

光电工程, 2009, 36 (4): 113, 网络出版: 2009-10-09

GPS 接收机伪码捕获自适应判决门限估计算法

Adaptive Threshold Estimation Algorithm for PN Code Acquisition in GPS Receivers

论文大纲

刘娣 ^*薄煜明邹卫军

作者单位

南京理工大学自动化学院，南京 210094

伪码捕获自适应门限平均捕获时间恒虚警概率 GPS GPS PN code acquisition adaptive threshold average acquisition time constant false alarm rate

摘要

GPS 接收机输入信号的功率随时间而变化，如果采用固定门限判决是否完成捕获会出现检测概率降低或虚警概率提高的问题。鉴于此，提出了采用自适应捕获门限判决策略完成信号捕获。采用最大似然估计原理，根据判决统计量的样本值得到了噪声方差的最大似然估计，进而求得恒虚警率下的自适应捕获门限。同时，信号的平均捕获时间是GPS 接收机性能的重要指标之一，研究了载波频率与伪码相位均为不确定值时的平均捕获时间的计算方法，推导了平均捕获时间与信噪比及门限值之间的约束关系。分析结果表明，自适应门限捕获方法能减小平均捕获时间，实现信号的快速捕获。

Abstract

Input signal power of GPS receivers changes with time. If fixed threshold is used to determine completion of the acquisition stage, two problems will arise, namely, decreasing in detection probability or increasing in false alarm probability. Therefore, it is proposed to apply a decision method for adaptive acquisition threshold in signal acquisition. Specifically, maximum likelihood estimation method is used on the sample data for decision statistic to obtain the maximum likelihood estimation value for noise variance. Afterwards, adaptive acquisition threshold can be obtained based on the Constant False Alarm Rate (CFAR). As the average acquisition time is one of the most important indexes of GPS receivers, calculation methods for the average acquisition time are analyzed for the case when both carrier frequency and PN code phase are uncertain. Furthermore, constraint relationship among acquisition time, Signal-to-noise Ratio (SNR) and threshold are derived. Analysis results show that adaptive acquisition threshold method can reduce acquisition time effectively, thus accomplish faster acquisition.

参考文献

[1] LIN David M，Tsui James Bao-Yen. Acquisition schemes for software GPS receiver [C]// Proceeding of the 11th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GPS-98, Nashville, Tennessee, USA, September 15-18, 1998. Alexandria：The Institute of Navigation，1998：317-325.

[2] Jari H J Iinatti. On the threshold setting principles in code acquisition of DS-SS signals [J]. IEEE Journal on Selected Areas in Communications(S0733-8716)，2000，18(1)：62-72.

[3] 巴晓辉，李金海，陈杰. 一种GPS 软件接收机自适应门限快速捕获算法[J]. 信息与控制，2007，36(1)：97-101.

BA Xiao-hui，LI Jin-hai，CHEN Jie. An adaptive threshold algorithm of fast acquisition for software GPS receivers [J]. Information and Control，2007，36(1)：97-101.

[4] Jiancheng Li，Tao Xu，Zhaowen Zhuang. The analysis of a novel adaptive PN-code acquisition for GPS DSSS receivers [C]//International Conference on Information and Automation, Changsha, China, June 20-23, 2008. New York, USA：IEEE，2008：889-893.

[5] 赵树杰，赵建勋. 信号检测与估计理论[M]. 北京：清华大学出版社，2005.

ZHAO Shu-jie，ZHAO Jian-xun. Signal Detect and Estimate Theory [M]. Beijing：Tsinghua University Publishing House，2005.

[6] 帅涛，任前义，刘会杰，等. 低轨卫星扩频系统中的PN 码混合并行捕获技术研究[J]. 通信学报，2007，28(10)：79-84.

SHUAI Tao，REN Qian-yi，LIU Hui-jie，et al. Hybrid parallel PN code acquisition technique for LEO satellite spread spectrum communication [J]. Journal on Communications，2007，28(10)：79-84.

[7] 薛巍，向敬成，周治中. 一种PN 码捕获的门限自适应估计方法[J]. 电子学报，2003，31(12)：1870-1873.

XUE Wei，XIANG Jing-cheng，ZHOU Zhi-zhong. An adaptive threshold estimation method for PN code acquisition[J]. Acta Electronica Sinica，2003，31(12)：1870-1873.

[8] Peterson Roger L，Ziemer Rodger E，Borth David E. 扩频通信导论[M]. 沈丽丽，侯永宏，马兰，译. 北京：电子工业出版社，2006.

Peterson Roger L，Ziemer Rodger E，Borth David E. Introduction to Spread Spectrum Communications [M]. SHEN Li-li，HOU Yong-hong，MA Lan. Beijing：Publishing House of Electronics Industry，2006

刘娣, 薄煜明, 邹卫军. GPS 接收机伪码捕获自适应判决门限估计算法[J]. 光电工程, 2009, 36(4): 113. LIU Di, BO Yu-ming, ZOU Wei-jun. Adaptive Threshold Estimation Algorithm for PN Code Acquisition in GPS Receivers[J]. Opto-Electronic Engineering, 2009, 36(4): 113.

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