New range domain carrier-smoothed code filtering with dual-frequency BDS data

In global navigation satellite system (GNSS) applications, the carrier-smoothed code is a widely used technique to combine code pseudo-range and carrier phase measurements. Unlike conventional methods, a method using dual-frequency GNSS data to improve smoothing accuracy by eliminating ionosphere delay is described in this paper. In the recursive least-squares theory for colored measurement errors framework, a global one-step carrier-smoothed code filter in range domain is proposed to overcome the limitations of traditional approaches. The correlations of the time-differenced carrier phase measurements are considered. This approach avoids overly optimistically evaluating the estimate and improves the transient accuracy of the estimate. Compared with stepwise strategy, the one-step method is superior and globally optimal. Experiments are conducted using real BDS data, and the performance of the proposed method is demonstrated.