一种全球定位系统卫星C/A信号通道绝对时延标定算法

A Delay Measurement Algorithm of C/A Signal Transmission Channel for GPS Satellite

为了精密测量全球定位系统(GPS)卫星C/A(Coarse/Acquisition)信号发射通道时延,提出了一种采用数字信号处理技术的标定算法.对GPS卫星输出的C/A导航信号和时间保持系统的Z计数脉冲进行双通道同步采样,在数字域完成C/A信号预处理后,进行多速率数字信号处理,获取C/A信号中伪随机码起始点;结合Z计数脉冲信号样本数据的处理结果,计算得到C/A信号发射通道的绝对时延.采样率为10GHz时算法标定结果的不确定度低于0.2ns.

The delay measurement accuracy of the transmission channel directly affects GPS users＇ positio ning precision and time transfer accuracy of GPS. To measure delay of C/A （Coarse/Acquisition）signal transmission channel high accurately, a delay measurement algorithm based on DSP （Digital Signal Pro cessing） was introduced. The C/A signal and the pulse of Z counter of time keeping system on GPS satel lite are sampling in synchronization. After C/A signal data pre processed, multi rate digital processing is made to decide the start point of PRN （Pseudorandom noise） code of C/A signal. With the processing re sults of Z pulse signal data, the delay of C/A signal channel is calculated out. The measurement uncertain ty with the proposed algorithm is less than 0.2 ns when the sampling frequency is 10 Gsa/s.