DS/FH信号跟踪的频率相位修正技术

直序/跳频(direct sequence/frequency hopping, DS/FH)扩频信号的跟踪受到多普勒效应和电离层效应的严重影响,使其难以应用于卫星导航的抗干扰领域。为了解决该问题,提出将递归最小二乘滤波修正的方法应用在DS/FH信号跟踪上。将处于不同通道中心频率的多普勒频率估计转化到DS/FH信号的整体中心频率进行并滤波,在频率捷变时对载波数控振荡器进行修正。根据对频率跳变前后载波相位和码相位突变的观察,实时估计电离层的电子密度,在频率捷变时修正载波相位和码相位。仿真实验证明,所提方法能够有效地消除DS/FH信号跟踪中的频率相位不连续问题,其跟踪精度与直序扩频信号度基本是相同量级。

Frequency and phase revision technique of DS/FH signal tracking

Tracking procedure of DS/FH (direct sequence/frequency hopping) spread spectrum signal is effected by Doppler effect and ionospheric effect seriously, which makes it hard to be used for the anti-interference field of satellite navigation. To solve this issue, a recursive least square based filtering was proposed to improve this stability of DS/FH signal tracking. The carrier Doppler estimation with variable center frequency in different channel was converted to the estimation with the center frequency of the DS/FH signal and filtered, and the numerically controlled oscillator of carrier was revised according to the predicted Doppler frequency as the frequency hops. The total electron content was estimated in real time by observing the carrier phase and code phase mutations, and the carrier phase and code phase was revised as the frequency hops. Simulation experiments demonstrate the proposed method is effective to eliminate the frequency and phase discontinuity of the DS/FH signal tracking, whose tracking accuracy can be the same level as DS signal.