中频数据卫星捕获算法研究

Satellite acquisition algorithm based on FFT data

软件无线电技术在卫星导航接收机中的应用在很大程度上改变了基带信号的处理方法。本文详细论述了基于FFT的频域快速捕获技术,通过对实测中频数据实验分析,指出仅利用门限方法无法准确在频域判决可视卫星,必须依靠其他信息进行辅助判决。在分析通过实测数据获得的可视卫星在连续扩频码周期内多普勒和伪码相位变化规律的基础上,给出了采用多普勒和伪码相位变化信息进行辅助门限捕获和完全采用多普勒和伪码相位变化信息进行捕获的两种算法。通过大量实验对两种算法进行验证,结果表明给出的算法在一定程度上降低了虚警概率,并具有较好的可靠性。

The application of software defined radio technology in satellite navigation receiver field has greatly changed the way of processing baseband signal. Based on the detailed discussion on fast acquisition technology in frequency domain using FFT, the paper pointed out that it can＇ t correctly find out all the visible satellites just only by means of a valve from the analysis of raw data, and it must need other information to assist to nmke it. Based on the analysis of the change rule of the visible satellites ＇ Doppler shift and code phase in the continuous code ＇ s period with the raw data, two acquisition algorithms were shown in the paper. The first algorithm used a valve to acquisition satellites with the help of the information of the Doppler shift and code phase, and the second only used the above discussed information of Doppler shift and code phase. At the end of the paper, the two algorithms were verified by lots of tests, and the test results showed that the above two algorithms could reduce false alarm probability to a certain extent and also have good reliability.