GPS SNR prediction in urban environment

The signal quality along with satellite availability & geometric dilution of precision plays a major role in GPS positional accuracy. In this study an attempt is made to develop a SNR prediction model for the urban environment. The height attribute value for 3D shapefile representing different urban environments is acquired from Cartosat-1 DEM and Total Station (which gave better accuracy in prediction). The best fit regression model correlating GPS signal SNR and satellite elevation angle in open environment for a GPS antenna was derived. The derived regression model between satellite elevation angle and signal SNR along with reflection and diffraction coefficients of surrounding urban environment was used to predict the GPS signal SNR at a given time.