Multipath level evaluation in the GPS relative positioning and its atenuation through multiresolution analysis

Abstract

The multipath effect affects the differential and relative positioning, even that
one involving short baselines. So it is necessary to detect this effect, check the
caused error level, and mainly, its removal. This paper aims at analysing and
comparing some useful components in the detection of this effect. These
components are the Signal to Noise Ratio (SNR), the values of MP1 and MP2
obtained from the TEQC software that indicates the multipath level in the
carriers L1 and L2, the multipath repeatability in consecutive days and the
elevation angle and the azimuth of the satellites. For this purpose, an experiment
is carried out, comparing such components in the presence and the absence of
reflector objects that cause the multipath. Not only there is clear multipath
repeatability in the residuals, but it also appears in the measures SNR, MP1 and
MP2, reaching up 99% of correlation. For reduction, at least, of the high
frequency multipath effect, the Multi-Resolution Analysis using wavelets is
applied in the double differences (DD) measures. Some statistical tests were
accomplished, which indicate results improvement, and mainly, larger reliability
in the solution of the ambiguities, reaching up 49% of improvement concerning
the Ratio test without applying the proposed method.