Ionosphere-corrected range estimation in dual frequency global navigation satellite systems receivers

In global navigation satellite systems (GNSSs), the measurement of the satellite-receiver pseudorange requires the estimation of signal´s delay. Because the accuracy of the latter affects significantly the accuracy of the final position, it is essential to consider the effect of various error sources. Ionosphere is commonly regarded as one of the most influential sources because of the fact that it can significantly delay the signal; therefore it is of paramount importance to mitigate its effects. In theory, a dual-frequency receiver can virtually eliminate the ionospheric effects if higher order effects are ignored. Although such an advantage has been widely recognised in the literature, the effect of the tracking error in the ionospheric correction and inherently on the range estimation is yet to be studied. In this study, the authors investigate the effect of tracking error on the ionosphere-corrected range in dual-frequency receivers and compare the performance of the traditional approach with least square (LS) and constrained LS methods, as well as with a new method for range estimation, proposed by the authors. The results showed that the traditional and LS methods perform well only under the restriction of zero tracking error, whereas the authors´ method has the best average performance.