基于小波的GPS接收机P码频域直接捕获技术研究

Research on Direct Acquisition Search Technique for P Code in Frequency Domain Based on the Wavelet for GPS Receiver

GPS接收机实现的关键技术包括伪随机码(PN)如C/A码、P码的生成和捕获、定位算法的实现等。C/A码短、易于直接捕获、用于粗测距,P码特长、难于直接捕获、用于精测距。P码直接捕获分为时域法和频域法,频域法比时域法效率高。P码频域的直接捕获法分为扩展复制重叠法XFAST、均值法和直接法。本文深入地研究了这些捕获法特点,提出了采用小波法提高P码频域的捕获效率,并对结果进行了分析。

The key technology to realize the GPS receiver includes generating and capturing PN code（such as C/A code and P code） and realizing some location algorithm.The precise time measurement of C/A code or P code is the key to measure distance precisely and get navigation text.C/A code which is short can be searched directly and is used to measure distance coarsely.Whereas P code which is too long can not be searched directly and is used to measure distance precisely.The direct acquisition search technique for P code is divided into time domain method and frequency domain method.The latter is efficient compared to the former.The frequency domain method includes the XFAST（Extended replica folding acquisition search technique） method,mean value method and direct method.The characteristics of the above methods are studied carefully in the paper.The direct acquisition search technique for P code based on the wavelet algorithm is put forward in the paper.Some results are discussed in the paper.