一种基于ARMA模型的GPS校频系统频率保持方法

A Method for Frequency Maintaining of GPS Calibration System Based on ARMA Model

GPS信号校准晶振信号频率源可输出高准确度时频信号。但当GPS接收机受到某些因素影响而无法接收GPS信号时,系统只能通过晶振自身保持一定的频率标准输出。晶振由于老化等因素,其输出频率会产生漂移。针对短期GPS信号丢失后晶振输出的频率漂移问题,提出一种基于ARMA模型的频率保持方法。利用GPS信号丢失前的系统历史校准数据,建立晶振性能退化模型,进而完成对系统输出频率的补偿,使其保持相对稳定的高准确度频率输出。将该方法应用到某GPS信号校准晶振信号频率源系统中,结果表明在短期GPS信号丢失后,预测的系统频率准确度平均相对误差可达1.80%。

The GPS signal calibrating crystal oscillator frequency source can output time frequency signal with high accuracy. However, when the GPS signals can not be received due to some factors, the system can only rely on the crystal oscillator to keep a standard output at a certain frequency. Influenced by aging and other factors, drift may arise in the output frequency of crystal oscillator. To correct and compensate for the output frequency drift at the time when losing the GPS signal, an algorithm is proposed based on ARMA model for maintaining the frequency source accurate. Through analyzing the historical calibrating data, the crystal oscillator performance degradation model is established, thus to implement the compensation for the system output frequency, and keep a relatively stable and highly accurate output frequency. The proposed method is applied to a GPS signal calibrating crystal oscillator frequency source, and the result shows that the average relative error of the system output frequency can remain at 1.80% after the GPS signal lost shortly.