A New Doppler-Smoothed Code Approach for Enhanced Accuracy in Low-Cost SDR-Based Multi-Constellation GNSS Receivers

For single-frequency GNSS receivers, high accuracy is achieved by utilizing carrier phase measurements along with pseudorange code measurements using Carrier-Smoothed Code (CSC) approach. However, under difficult conditions like urban areas or high dynamics, the signal tracking can be lost. This causes cycle slips and introduces errors in positioning. To fix the problem, Doppler-Smoothed Code (DSC) as an alternative was looked at. Measurements of Doppler are resistant to cycle slips but noisier than carrier phase measurements. In this paper, we introduce a new DSC approach based on averaging Doppler measurements from the tracking loops in a SDR receiver architecture. The results show that the proposed DSC approach is proved to remain immune to cycle slips, similar to current DSC algorithms, at the same time the positioning error is 31% lower. The introduced positioning error is only 0.05% higher compared to CSC algorithm. This promote using DSC as a primary smoothing approach.