Performance of GPS sidereal filters during a satellite outage

Abstract

Sidereal filtering is the name of a technique used to reduce the effect of multipath interference on a GPS position time series associated with a static or quasi-static antenna. This article assesses the impact of a GPS satellite outage on the performance of a sidereal filter. Two different types of sidereal filter are tested: a position-domain sidereal filter (PDSF) and an observation-domain sidereal filter (ODSF). A satellite outage is simulated at two static receivers with contrasting antenna types and multipath environments. At both stations, the ODSF is more effective than a PDSF at removing multipath error over averaging intervals under around 200 seconds in length whether there is an outage or not. However, difference in the performance of the two types of sidereal filter was much more significant at the station more prone to multipath interference. The results are particularly relevant for applications where high-rate precise point positioning (PPP) is used for monitoring: If a PDSF is applied, then errors due to highfrequency multipath interference may still alias into the resulting position time series if a satellite outage occurs and possibly increasing the false alarm rate. In contrast, an ODSF is likely to perform better in such circumstances.

Keywords

• allan deviation
• carrier phase
• global positioning system
• high-rate
• multipath
• precise point positioning
• satellite outage
• sidereal filtering