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基于非相干积分的GNSS弱信号捕获

清华大学 辅仁网/2017-07-07

基于非相干积分的GNSS弱信号捕获
郑伦贵,尤政(),张高飞,赵书敏
Acquisition of weak GNSS signals based on non-coherent integration
Lungui ZHENG,Zheng YOU(),Gaofei ZHANG,Shumin ZHAO
Department of Precision Instruments, Tsinghua University, Beijing 100084, China

摘要:
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摘要当接收机天线被建筑物遮挡或信号被强噪声淹没时,接收机为正常捕获信号,需进行长时间相干积分和多次非相干积分以提取全球卫星导航(GNSS)弱信号,但长时间相干积分会因为导航数据位跳变导致积分后信号能量衰减影响捕获,且多次非相干积分会带来平方损耗限制了对弱信号的捕获能力。针对这一问题,该文在非相干积分基础上提出以最大能量为准则估计最优导航数据位方法,消除导航数据跳变对积分时间长度限制,从而提高弱信号的捕获能力。捕获仿真结果表明: 该方法能大幅提高增益,可捕获到20 dBHz的弱信号。

关键词 非相干积分,弱信号,最优导航数据位,捕获能力
Abstract:When antennae are blocked by buildings or the signals are drowned by strong noise, global navigation satellite system (GNSS) receivers require both long coherent integration times and a large number of non-coherent integration operations to acquire the signal. However, navigation data bit transition during the long coherent integration results in integrator signal energy attenuation and non-coherent integration will have squared losses that limit the ability to acquire weak signals. A signal acquisition algorithm is given here based on non-coherent integration that estimates the optimal combination of navigation data bits with the maximum energy criterion to eliminate the length limit and improve the ability to acquire weak signals. Tests demonstrate that these techniques greatly increase the gain such that low signal to noise ratio (SNR) signals as low as 20 dBHz can be successfully acquired.

Key wordsnon-coherent integrationweak signaloptimal navigation dataacquisition capability
收稿日期: 2013-09-09 出版日期: 2015-03-17
基金资助:国家“八六三”高技术项目(2013AA122601)
引用本文:
郑伦贵,尤政,张高飞,赵书敏. 基于非相干积分的GNSS弱信号捕获[J]. 清华大学学报(自然科学版), 2014, 54(6): 794-798.
Lungui ZHENG,Zheng YOU,Gaofei ZHANG,Shumin ZHAO. Acquisition of weak GNSS signals based on non-coherent integration. Journal of Tsinghua University(Science and Technology), 2014, 54(6): 794-798.
链接本文:
http://jst.tsinghuajournals.com/CN/ http://jst.tsinghuajournals.com/CN/Y2014/V54/I6/794


图表:
GNSS信号捕获原理图
方法1(相干积分10 ms, 非相干120次)的捕获结果
方法2(相干积分20 ms, 非相干积分60次)的捕获结果
方法3(相干积分40 ms, 非相干积分30次)的捕获结果
捕获方法 Doppler频移/Hz 码相位偏差/码片
1 捕获失败 捕获失败
2 220 960
3 220 960


3种方法捕获结果对比


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