基于硬件信号模拟器的电离层TEC监测仪 差分码偏差长期变化

利用硬件信号模拟器可以标定电离层TEC监测仪的差分码偏差.通过对相同接收机时隔近41.5月进行的两次差分码偏差标定实验，以GPS系统为例分析了硬件标定法得到的差分码偏差随时间的长期变化情况.结果表明:接收机差分码偏差均值从第一次实验的16.122ns增加至第二次实验的16.749ns，在约41.5月的时间内增加约0.627ns，月增量为0.0151ns，增加比较缓慢；第二次实验的差分码偏差标准差也有所增加，但增量也不大（均值分别为0.05ns和0.07ns）.此外，两次标定实验的TEC测量精度（均方根误差）均达到约0.3TECU，对应的差分码偏差误差约0.1ns，这说明该接收机差分码偏差变化的一致性较好.若不加以再次标定，第二次实验时TEC测量误差将增加至约1.8TECU，月增量约为0.0434TECU. 

Long-term Variation of Differential Code Biases of Ionospheric TEC Monitor Based on Hardward Signal Simulator

Hardware signal simulator can be used to calibrate the hardware delay of the ionospheric TEC monitor. In this paper, the long-term change of DCB derived by hardware calibration method is analyzed, by two independent calibration experiments (with a time interval of nearly 41.5 months) on the same receiver (for GPS signals). The results show that the mean DCB value of the receiver increases from 16.122ns in the first experiment to 16.749ns in the second experiment. It increases 0.627ns in about 41.5 months. The monthly increment of DCB is about 0.0151ns. The standard deviation of DCB increases slightly from 0.05ns to 0.07ns between the two experiments. In addition, the TEC calibration accuracy (Root Mean Square Error) of both two experiments reach about 0.3TECU, and the corresponding DCB errors reach about 0.1ns. It indicates that the DCB variation between different channels is quite consistent. In the second experiment, the TEC measurement error will increase to about 1.8TECU if using the DCB value obtained in the first experiment. The monthly increment of TEC error is about 0.0434TECU.