Wavelet Transform for GPS Carrier Phase Multipath Mitigation

In order to mitigate multipath disturbance in Global Positioning System (GPS) high-accuracy carrier phase positioning, a data processing technique, based on residual analysis and wavelet transform, is investigated for reducing the double difference carrier phase multipath. As for short baseline, errors resulting from ionosphere, troposphere and satellite orbits are assumed to be insignificant and are safely ignored. Therefore, the double difference carrier phase residuals mainly consist of multipath and observation noise. The wavelet transform is employed to decompose the double difference residuals into a high-frequency noise term and a low-frequency multipath term, and then the extracted multipath term is applied directly to GPS observations to correct for the multipath effects. Experiments have shown that 47-62% improvement can be achieved in GPS positioning accuracy after multipath corrections are applied. The method can be used to successfully mitigate multipath from GPS observations.