Multiresolution real-time (MRRT) code-smoothing technique

Abstract

Global Navigation Satellite System (GNSS) receivers provide diverse measurements, namely the code and carrier phase measurements. The measurements' rates between successive epochs are similar in both observables, but the change in carrier phase can be determined on one order of magnitude higher than the change in code. This diversity of measurements is used in the measurements domain to improve position accuracy. The code measurements are contaminated with diverse errors that fall in different frequency bands (i.e., multipath error, falls in a high to medium frequency band 0.1 to 0.003 Hz, whereas the ionospheric error is in the lower frequency band 0 to 1.2e4 Hz). As these errors have different frequency components, the methodology is presented whereby the multipath error can be mitigated through frequency domain processing. In this article, an innovative codesmoothing technique is used, namely multiresolution real-time (MRRT) code-smoothing technique. This technique is used in real-time scenarios to mitigate multipath error (medium to high frequency) and noise (high frequency) and to retain the ionospheric error (low frequency) untouched in the mitigation procedure. The proposed MRRT technique is superior to those in the literature in the way that it can effectively remove the multipath and noise in real-time scenario and retain the smoothed code unbiased with low variance.