GPS信号的多普勒频移和时移分析推算

Analysis and Calculation on Doppler Frequency-shift and Time-shift of GPS Signals

对GPS信号总是采用相干接收和处理，本地信号需要时刻保持与卫星信号之间频率和码相位的严格对准。GPS卫星和用户的运动将使接收信号的频率发生改变，同时也将使信号中的码速率发生改变，从而影响对信号的捕获、跟踪和对伪距的测量，这成为GPS接收机设计者和对抗者关注的焦点之一。文章仔细分析推算了多普勒频移和时移及其变化率，取得了重要数据，并简要分析了对环路的影响。

The methods of coherent receiving and processing are always adopted to process GPS signals. The local signals should be aimed at the satellite signals strictly in frequency and code phase. The frequency of received signals will change because of the movement of the GPS satellite and the users, and the code rate of the signals will also change, and it will affect the capture and track to signals, and also will affect the measurement to pseudo range. Such problem has become one of the important points to the designers and counters of GPS receivers. The Doppler frequency-shift and time-shift and their changing rate are analyzed and calculated carefully in this paper, and the useful data is achieved. And the effect to the loop is also analyzed in brief.