Code-Carrier Divergence for Ground Based Augmentation System: A comparative analysis study

Carrier-Smoothed-Code (CSC) can effectively suppress the multipath effect and receiver noise in the code-based differential positioning, which is widely adopted by the Ground Based Augmentation System (GBAS). However, the accuracy of smoothed code can be degraded significantly by the Code-Carrier-Divergence (CCD) effect. The CCD monitoring technology of for BeiDou Satellite System (BDS) is still under developing. This paper analyzed and compared two methods of CCD monitoring in GPS and BDS, respectively. Based on the CCD monitoring results, it was found that the tow-order linear invariant filter is better for CCD in terms of detection time and estimation accuracy. With the given constant false alarm rate, CCD detection threshold can be obtained. Furthermore, the sigma-inflation method is used to compensate the non-perfect distribution of the constructed test statistics. The real-world experiment of GPS and BeiDou is implemented to make a comparative analysis. The experimental result shows that the two-order detection method is more applicable to BDS due to the better availability.