| 摘要: |
| 在现阶段，“北斗”B1I信号在D1导航电文中引入现代化GPS和Galileo系统常用的二次编码调制，使得比特跳变周期变短，降低了系统的捕获灵敏度。为解决上述问题，提出了一种基于码元排布顺序的改进相干累积捕获算法，通过分组来遍历并统计一个数据段的累加和相关值，并且采用一种改进的判决方法进行双重判决，最终确定其中最大相关值并完成捕获。此方法有效延长了积分长度，克服了因Neumann-Hoffman（NH）码造成的相干累积时间过短的缺陷，能改善在低信噪比环境下的信号捕获能力。在高斯白噪声模型下对各个捕获算法进行的仿真对比结果表明，所提算法在低信噪比（-36~-34 dB）情况下，与补零算法相比，信号捕获灵敏度有约1.7 dB的提升。 |
| 关键词: “北斗”信号 弱信号捕获 NH码 相干累积 判决算法 |
| DOI： |
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| 基金项目:国家自然科学基金资助项目(61563004) |
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| A Beidou weak signal acquisition algorithm to avoid influence of secondary coding |
| LI Mengheng,LAO Yuanji,WANG Zhonghao,QIN Tuanfa |
| (a.School of Computer and Electronic Information;b.Guangxi Key Laboratory of Multimedia Communications and Network Technology,Guangxi University,Nanning 530004,China) |
| Abstract: |
| The commonly used twice-coded modulation in modern GPS and Galileo system is introduced in D1 navigation message of Beidou B1I signal，which will reduce the navigation data transition period and the acquisition sensitivity of the system. To solve above problems,an improved coherent accumulation acquisition algorithm based on symbol arrangement order is proposed. The grouping method is used to traverse and count the accumulation and correlation values of data segments,and an improved decision method is used for double decision,and the maximum correlation value is finally determined and captured. The proposed algorithm extends the integral accumulation length and overcomes the defect of low coherent accumulation time caused by the influence of Neumann-Hoffman(NH) code. The simulation results of different acquisition algorithms under the Gaussian white noise model show that in the case of low signal-to-noise ratio(-36~-34 dB),the signal acquisition sensitivity of the proposed algorithm is about 1.7 dB higher than that of the zero-padding algorithm. |
| Key words: Beidou signal weak signal acquisition NH code coherent accumulation decision algorithm |
