GPS实施的是“到达时间差”（时延）的概念：利用每一颗GPS卫星的精确位置和连续发送的星上原子钟生成的导航信息获得从卫星至接收机的到达时间差-GPS implementation is the " time difference of arrival" (delay) concept: the use of each GPS satellite and the exact location of the satellite atomic clocks generated by