iGMAS GNSS钟差产品综合与评估

高精度卫星导航定位离不开精密钟差改正信息,钟差产品综合与评估是产品综合与服务中心(ISC)的重要任务之一。本文首先介绍了ISC钟差产品综合策略和抗差估计方法,重点阐述了非线性系统误差处理、钟差参考基准统一及残余线性偏差补偿;然后,对比逐历元对准方法和"三步"校准法两种不同综合产品的精度和稳定性,并对iGMAS近两年的钟差产品进行了评估和详细分析;最后,为验证综合产品的精度和一致性,采用5个测站的静态数据进行了PPP测试。计算结果表明:综合钟差的RMS最优且稳定,可作为评估分析中心产品精度的参考解。此外,综合产品北斗单系统静态PPP的结果优于多数分析中心,位置精度在4cm以内。

Combination and Assessment of GNSS Clock Products from iGMAS Analysis Centers

The precise clock corrections are a prerequisite for applications of the GNSS positioning, navigation and timing (PNT) service.Therefore the combination and assessment for clock products is one of the important tasks of product integration and service center (ISC).First of all, it is introduced that the improved strategy and robust estimation of clock combination.The issues including nonlinear systematic error processing, alignment of clock reference and compensation of linear systematic error are highlighted.Furthermore, two combined products using epoch-wise clock alignment and the "three-step" alignment respectively are compared, and the clock products of recent two years from iGMAS are analyzed and evaluated in detail.Finally, in order to verify the accuracy and consistency of the combined products, PPP tests are implemented using static data from 5 IGS stations.The results show that the clock RMS of combined solutions is the best, which can be used as reference to assess the clock quality of analysis centers (ACs).The results of BDS only static PPP using the final combined products is within 4cm, which is better than that of most ACs.