Feasibility of easy-to-implement methods to analyze systematic errors of multipath, differential code bias, and inter-system bias for low-cost receivers

The low-cost receiver with multi-frequency and multi-constellation Global Navigation Satellite System (GNSS) observations is becoming the mainstream in positioning and navigation. It is crucial to estimate systematic errors, including the multipath, differential code bias (DCB), and inter-system bias (ISB) for such receivers. The traditional analysis strategies are based on the geometry-free and ionospheric-free method, or the geometry-based and ionospheric-corrected method, whereas they cannot work all the time. Several easy-to-implement methods are discussed and analyzed, including the geometry-fixed and ionospheric-corrected method, the geometry-free and ionospheric-corrected method for multipath, the geometry-free and ionospheric-corrected method for DCB, and the geometry-fixed and ionospheric-corrected method for ISB. To mainly assess the performance of the above methods, dual-frequency and single-frequency low-cost receivers are both used. The results indicate that for the multipath, all different assessment methods have their applicable conditions, and pros and cons. The easy-to-implement methods can still work regardless of the numbers of satellites and frequencies in most cases. According to the results of the DCB and ISB, by using the traditional and convenient methods, the behaviors are highly similar, thus certifying the feasibility of the easy-to-implement methods. It can also be concluded that the multipath cannot be ignored easily in low-cost receivers due to its large magnitude, and the DCB and ISB are relatively stable over 5 days.