Analysis of variations of GPS multipath sidereal day-to-day repeatability based on CVVF method

The property that the site-dependent errors repeat themselves every sidereal day due to the largely repeating satellite-reflector-antenna geometry has been used extensively to reduce the effects of GPS multipath. To better understand the variations in the sidereal day-to-day repeatability of GPS multipath signals, we analyze about two-week GPS carrier phase observations collected on a static baseline over a time period of about three months. The Cross-Validation Vondrak Filter (CVVF) proposed earlier by the authors is used to filter the noise in the series of GPS carrier-phase residuals and the calculated point coordinates. A multipath model is also derived with the CVVF method and used to remove the multipath errors in the GPS observations of the subsequent days. The results indicate that the day-to-day repeatability of GPS multipath signals decreases quickly with time and when the time interval is over about 10 days, the property can no longer be used to mitigate effectively GPS multipath errors. Comparison and correlation analysis between the time series of different days are then made to identify abnormal variations in the time series and to relate the variations to possible causes.