PMF-FFT方法在P码捕获中的改进及参数设计

部分匹配滤波器与FFT相结合的捕获模型使用在高动态环境下导航信号的捕获中,由于它对多普勒频率误差有较高的容忍度,因此可以直接进行频域的并行搜索,大大降低了平均搜索时间,并使整个系统依然具有较高的检测概率. 文中通过建立数学模型,对PMF FFT捕获算法的原理及特性及其在捕获流程中的各部分损耗进行了详细的分析,并针对P码的非周期特性,使用重叠保留法对PMF FFT算法进行了改进,使用基于FFT的并行码相位搜索的方法,在频域内实现了时域相关运算,进一步减少了捕获时间. 最后依据“达到等效判决信噪比时总运算时间最少”原则,对算法中各项参数的设计提出了指导意见,具有一定的参考价值。 

Parameter Design of an Improved PMF-FFT Algorithm in P-code Acquisition

The acquisition model of partial matched filter combined with FFT is used in the acquisition of navigation signals in high dynamic environment. Because of its high tolerance to the Doppler frequency error, it can do parallel search in frequency domain, which reduces the acquisition time and enables the whole system to have a high detection probability. This paper analyses the principle of the PMF FFT acquisition algorithm and the loss of each part in the acquisition process in detail by establishing the mathematic model, and then comes up with an improved acquisition method according to the aperiodic characteristics of the P code. The overlap and save method is applied to achieve time domain parallel search in the frequency domain. Through this method, the acquisition time can be further reduced. Finally, according to the principle of the minimum total operation time when reaching the equivalent signal to noise ratio, some guidance to the optimum design of the parameters in the algorithm is given, which has a certain reference.