论文部分内容阅读
在城市、峡谷等复杂环境下,卫星导航信号衰减严重,接收机导航定位性能变差,甚至不能工作,给国民生产生活带来诸多不便。提高接收机弱信号的跟踪能力,研究高性能的卫星导航接收机具有重要的意义和价值。在研究分析GPS、北斗D1导航电文的调制方式和相干积分方法的基础上,构建了一种改进直方图的位同步方法,该方法借鉴直方图的思想,通过设定比特跳变的统计门限上限和多组门限下限找到比特跳变边沿。在此基础上设计实现了一种长时间相干积分方法,该方法兼容GPS电文和北斗D1导航电文,可以有效地消除导航电文跳变或者NH码跳变带来的比特翻转。最后,在FPGA平台验证了该方法可以有效提高信号信噪比,以及接收机在弱信号环境下的跟踪能力。
In the complex environments such as cities and gorges, satellite navigation signals are seriously attenuated, and the navigation and positioning performance of receivers deteriorates or even fails to work, which brings inconvenience to national production and living. It is of great significance and value to study the tracking capability of weak receiver signals and research on high performance satellite navigation receivers. On the basis of studying and analyzing the modulation method and coherent integration method of GPS and BeiDou D1 navigation message, a bit synchronization method of improved histogram is constructed. By using the idea of histogram, the method sets the upper limit of statistical threshold of bit transition And multiple sets of thresholds to find the bit transition edge. On this basis, a long time coherent integration method is designed and implemented. This method is compatible with GPS message and Beidou D1 navigation message, which can effectively eliminate bit reversal caused by navigation message hopping or NH code hopping. Finally, the FPGA platform verifies that the proposed method can effectively improve the signal-to-noise ratio of the signal and the tracking ability of the receiver in the weak signal environment.