生成GPS中频数字信号，卫星数2，为1和11号卫星，信噪比，采样率可调，目前采样率5M，请在linux下运行，先阅读readme，按照步骤进行-IF digital signal to generate GPS satellite number 2, for 1 and 11 satellites, signal to noise ratio, adjustable sample rate, the current sampling rate 5M, please run under linux