Error reduction in GPS datum conversion using Kalman filter in diverse scenarios

The coordinates of a location obtained from a Global Positioning System (GPS) receiver depend on the type of environments. This paper discusses the errors in GPS coordinate conversion from the World Geodetic System 84 (WGS84) to the Universal Transverse Mercator (UTM) system, in different environments and their reduction using Kalman filter. 30 samples of positional coordinates, each for three different cases i.e open area, amidst tall buildings and area having heavy vehicular traffic, have been collected, with the time interval between two successive samples being 1 to 2 minutes. The samples were collected using a Garmin eTrex GPS receiver, which gives the coordinates of a location in both the WGS84 and UTM formats. The collected samples clearly indicated a greater variation in the coordinates for the location surrounded by tall buildings and the location which had a heavy flow of vehicular traffic as compared to the open area without any obstacles. The variation in coordinates can be attributed to multi path errors that occur due to the presence of tall buildings and moving vehicles. After applying a Kalman filter to the UTM values, a considerable improvement in their consistency has been observed.