假设移动用户从距离基站1英里的地方开始以每小时40英里的恒定速度相基站移动，仿真移动用户在这2s时间间隔内所接收的信号（及其频谱）-Suppose mobile user from the base station a mile from the start where the constant speed of 40 miles per hour relative to the base station mobile, mobile users in the 2s simulation time interval the received signal (its spectrum)