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Single Frequency Multipath Mitigation Based On Wavelet Analysis

Published online by Cambridge University Press:  20 April 2007

Mohammad Aram ,
Ahmed El-Rabbany ,
Sri Krishnan  and
Alagan Anpalagan
Mohammad Aram
Affiliation:
(Ryerson University, Toronto) (Email: maram@ryerson.ca)
Ahmed El-Rabbany
Affiliation:
(Ryerson University, Toronto) (Email: maram@ryerson.ca)
Sri Krishnan
Affiliation:
(Ryerson University, Toronto) (Email: maram@ryerson.ca)
Alagan Anpalagan
Affiliation:
(Ryerson University, Toronto) (Email: maram@ryerson.ca)
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Abstract

Multipath is still one of the major error sources that degrades the accuracy of GPS positioning. The amount of multipath is highly dependent on the antenna's environment, which makes it difficult to isolate. Usually there is at least one in-view satellite which is more susceptible to multipath, particularly the one with the lowest elevation angle. To increase the positioning the best satellites must be selected (i.e. by least square or multipath mitigation) for computing a position. In this paper we propose an algorithm which picks up the best satellites (when there are more than four satellites in view) based on wavelet analysis for calculating a position. In this experiment, code and carrier measurements were collected in 15-minute segments by exploiting a single frequency (L1), stationary, navigation-grade receiver in a high-multipath environment. The magnitudes of these pseudoranges were often inflated by multipath error. We then post-processed the received data by applying wavelet filtering to the residuals (code minus carrier) to approximate the multipath values, and compute the receiver's position based on the selected satellites. Satellites were selected based on the residual values. To compare the results with the raw measurements, statistical elements were computed. The results showed significant improvement in variance of the estimated positions and, most importantly, a normalization of the data scatter-distribution was observed.

Keywords

MultipathWavelet analysisGPS

Information

Type
Research Article
Information
The Journal of Navigation , Volume 60 , Issue 2 , May 2007 , pp. 281 - 290
Copyright
Copyright © The Royal Institute of Navigation 2007

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References

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