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介绍了一种GPS软件接收机的设计方法.该设计采用软件无线电设计理念,主要包括前端模块、捕获模块、跟踪模块、同步模块、导航解算模块以及其他辅助模块.捕获模块采用基于圆周相关的捕获算法,通过FFT(快速傅立叶变换)分别作用于输入信号和本地码信号将运算变换到频域内处理.该算法可得到C/A码起始相位和分辨率为1kHz的载波频率信号,但此载波频率精细度差,不能直接用于跟踪环路.为提高载波频率分辨率,采用基于相位关系计算的精频估计算法.实验表明应用精频捕获算法得到的载波精频估计误差在几赫兹以内,可直接用于后续跟踪环路.
This paper introduces a design method of GPS software receiver, which adopts the concept of software radio design, including front-end module, capture module, tracking module, synchronization module, navigation solution module and other auxiliary modules. The acquisition module uses a circle- Capture algorithm that transforms the operation into the frequency domain by applying FFT (Fast Fourier Transform) to the input signal and the local code signal, respectively, which can obtain the initial phase of the C / A code and the carrier frequency signal with a resolution of 1 kHz, Carrier frequency precision can not be directly used in tracking loop.In order to improve the carrier frequency resolution, the phase estimation algorithm based on the fine frequency estimation algorithm experiments show that the use of precision frequency acquisition algorithm to obtain the carrier frequency estimation error within a few Hertz , Can be used directly for follow-up loop.