GPS接收机硬件延迟时变特性分析

在全球定位系统(Global Positioning System，GPS)中，接收机硬件延迟引起的码偏差和相位偏差是影响精密授时、电离层建模以及非差模糊度解算的重要因素。利用GPS对电离层总电子含量进行估计和建模时，通常假定GPS接收机硬件延迟偏差是稳定不变的量，对其可能存在的波动及影响因素考虑不充分。因此，对GPS接收机硬件延迟偏差的时变特性进行分析，有助于提高电离层电子含量估值的准确性和可靠性。分析了GPS接收机差分码偏差(differential code bias，DCB)和差分相位偏差(differential phase bias，DPB)单历元及单天解的时间变化特性，并对温度变化与接收机DCB、DPB变化之间的相关性进行了实验探究。结果表明，接收机重启前后其DCB值会发生突变，重启之后接收机DCB和DPB大约需要25 min才能趋于稳定。接收机DCB和DPB并不能长期保持稳定，实验数据显示，在2~3 h内，DCB的变化量可以达到0.8 m左右，DPB的变化量可以达到4 mm左右，接收机DCB和DPB的波动与周围环境温度的变化具有较强相关性。

Analysis of Time-Varying Characteristic of GPS Receiver Hardware Delay

In the Global Positioning System (GPS), the receiver hardware-induced code and phase biases are important factors affecting precise timing, precise modeling of ionosphere and un-difference ambiguity resolution. In the estimation and modeling of ionospheric electron content, it is generally assumed that the GPS receiver hardware biases are constant amounts, without considering the possible fluctuations and influencing factors. Therefore, to analyze the time-varying characteristics of receiver hardware biases can help improve the accuracy and reliability of the ionospheric electron content estimation. In this paper, the time-varying characteristics of single-epoch and single-day solved GPS receiver differential code bias (DCB) and differential phase bias (DPB) are analyzed, and the correlation between the variation of receiver hardware delay and the change of ambient temperature is explored experimentally. The results indicate that receiver DCB will mutate after a restart. And after restarting, the receiver DCB and DPB have a changing process, which takes about 25 min, afterwards they keep stabilized. Also, it's worth noting that the receiver DCB and DPB cannot be stable for a long time. The experimental results show that the change of receiver DCB and DPB can reach about 0.8 m and 4 mm in 2-3 h. In addition, the fluctuation of receiver hardware delay has a strong correlation with the change of the vicinity temperature.