基于Kalman滤波的GPS跟踪环路晶振闪烁噪声建模方法

摘要

Frequency drift caused by oscillator will pollute carrier phase and Doppler frequency in GPS receiver. Therefore, it is necessary to model the oscillator error in the tracking system. The flicker noise error of oscillator can not be exactly modeled in Kalman system, which causes errors in the model of traditional Kalman-based tracking loop. To solve these problems, the frequency domain model and noise covariance of oscillator were analyzed, and a method of exactly modelling the flicker noise in the Kalman-based tracking loop was proposed. Real GPS satellite data was processed by using the new oscillator model to verify the validity.%由于晶振频率漂移对GPS接收机的载波相位和频率跟踪带来了误差,在载波跟踪系统中需要对晶振误差进行建模.传统基于Kalman滤波的跟踪方法无法对非白的闪烁晶振误差进行准确建模,导致跟踪环路建模产生一定的误差.针对上述问题,文章重点分析了晶振的频域模型建模过程和噪声协方差求解问题,提出了Kalman滤波中晶振闪烁噪声的近似建模方法,并用实际卫星数据验证了建模的正确性.