一种基于GPS C/A码引导的P码捕获方法

针对GPS系统P码(Precision Code)信号多普勒频移大、码周期长和速率高的特点带来的捕获慢且资源消耗较多的问题,提出了一种新的基于GPS C/A(Coarse/Acquisition Code)码引导P码捕获的方法。系统首先完成C/A码捕获,然后向新型P码发生器置入引导信号zv_set,在接下来的第1个1.5s码周跳变沿对V1和V2置入计数初值;在码同步信号的驱动下,V1和V2进行循环计数,等到V2=0时,P码码值正确,返回引导完成标志。通过仿真分析,该方法资源占用率减少了50%。结果表明该方法可有效避免繁琐的运算,适用于星载GPS双频导航接收机设计。

A method of P code acquisition base on GPS C/A code

Because of the GPS P code's own features: longer Doppler shift,longer duration and higher speed,there is more resource and time consumption in the traditional GPS P code acquisition. A new P code acquisition method base on C/A code guide is proposed to resolve the problem. The system first finish the acquisition of C/A code,then en-able the zv_set guide signal in the new type P code generator, set the initial value of V1 and V2 counter until the first 1.5s code cycle's edge arrived. The V1 and V2 start cycle count under the code synchronization signal drive, the P code is generated and the guide end flag is enabled when the V2 reached to zero. Simulation result shows that the method reduced 50% resource consumption,suitable for satellite dual-frequency GPS navigation receivers.