This paper analyzes the quality of the double differenced measurements in the presence of multipath. In order to improve the quality of the measurement, this paper designs a carrier smoothing filter and a shaping filter using the properties of the double differenced measurements. The carrier smoothing method is applied to reduce the code measurements covariance and the shaping filter is designed using the first order Markov process.

Keywords: multipath, CDGPS, shaping filter, carriersSmooth, code measurement