中文说明：采用延时相乘法实现GPS信号的捕获，模拟产生三颗卫星的信号，然后通过延时相乘并进行频谱分析来得到伪码和多普勒频移
English Description：
The acquisition of GPS signal is realized by delay multiplication, and the signals of three satellites are simulated, and then pseudo code and Doppler frequency shift are obtained by delay multiplication and spectrum analysis