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在卫星导航接收机的设计和实现过程中,信号捕获是卫星信号同步的关键步骤。只有捕获到了正确的相位和多普勒信息,才能初始化跟踪环路,进而完成信号的同步。针对高动态接收机在大频偏条件下实现信号捕获需要进行多次频域搜索,计算量成倍增加的问题,该文以GPS系统为例,分析了多普勒频偏对相关峰的影响,利用频域叠加技术设计了在多普勒频移过大条件下的信号捕获方案。分析结果表明,该捕获方案可以完成大频偏下的信号捕获,降低了多次频域搜索带来的计算量,并且具有较好的捕获性能。
In the design and implementation of satellite navigation receiver, signal acquisition is the key step of satellite signal synchronization. Only capture the correct phase and Doppler information, to initialize the tracking loop, and then complete the signal synchronization. In order to realize signal acquisition under high frequency offset conditions, high-dynamic receiver needs to search many times in the frequency domain and the computational complexity is doubled. Taking GPS system as an example, the influence of Doppler shift on correlation peak is analyzed , The signal acquisition scheme under the condition of excessive Doppler shift is designed by using the frequency domain superposition technique. The analysis results show that this acquisition scheme can accomplish the signal acquisition under large frequency offset, reduce the computational load caused by multiple frequency search, and has good acquisition performance.