北斗导航卫星相位中心修正

Antenna Phase Center Correction for BeiDou Navigation Satellite

  • 摘要: 北斗卫星导航系统(BeiDou navigation satellite system,BDS)发播电文时利用卫星钟差a0参数修正了B3频点相位中心与质心差异的大部分偏差,利用卫星群延时间参数(timing group delay,Tgd)修正不同频点相位中心的差异部分。该方法实质是利用各向同性的卫星钟差修正具有各向异性的天线相位中心偏差,改正精度有限。为进一步提高广播星历精度,提出了先对卫星位置进行相位中心改正,再对相位中心的轨迹进行广播星历拟合的处理方法,分别比较了两种改正方法对用户距离误差(user range error,URE)以及精密单点定位精度的影响。分析表明,两种方法都能使URE和定位精度得到提高,且新方法比利用卫星钟差a0参数的修正精度提高了约76%,定位精度提高了约12.5%,同时新方法的改正精度不受时空因素影响。利用广播星历拟合修正天线相位中心与不进行天线相位中心比较,定位精度提高约38.1%。最后分析了Tgd参数修正各频点天线相位中心不一致的残差,影响在毫米级,可以用于修正相位中心的频间差异。

     

    Abstract: Presently, much of the errors caused by the B3 frequency, antenna phase center offset is corrected by the satellite clock a0 parameter. Errors caused by the variance of different frequencies are corrected by timing group delay(Tgd) parameter for BeiDou navigation satellite system(BDS) through navigation messaging. In order to improve the broadcast ephemeris, we put forward a satellite antenna phase center offset correction and fitting broadcast ephemeris methods. The two approaches are compared in two ways, including the influence on user ranging error and precise point positioning. The results show that the two methods can correct most errors caused by antenna phase center offset. The correction accuracy of the new method was improved by 76% compared with the method using satellite clock a0 parameter, and the positioning accuracy was improved by 12.5%. Accuracy is not affected by time-space factor. The positioning accuracy when correcting the satellite position before ephemeris fitting is about 38.1% higher than when satellite antenna, phase center offset is not corrected. The correction Tgd residuals of the variance of different frequencies of the antenna phase center are analyzed. The results show that the influence is at the mm order, so we can correct the variance by Tgd parameter.

     

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