Real Time Processing of GPS Data Using DSP Techniques

Abstract

The Navstar Global positioning system is all weather, space based navigation system developed by the department of defense to satisfy the requirements for the military forces for accurately determining their position, velocity and time in common reference system, anywhere on or near earth on continuous basis. It is used in various applications such as agriculture, navigation, Mapping and Surveying, Military. The major problems in GPS measurements may be due to tall buildings, high mountains, and overhead foliage. The positioning data provided directly by the satellites are subject to variety of error sources such as thermal noise, tropospheric delays, multipath error, ephemeris errors, satellite clock errors and ionospheric delays before they are processed into position and time solution in the GPS receiver. The work is based on case studies. An experimental set up is made using two standard handheld GPS receivers. The effect of weather and altitude of particular location is also considered.DSP techniques such as Bad Data identification and modification and Kalman filter are used to enhance the accuracy of GPS measurements. In the work the combination of DSP technique Kalman filter after Bad Data identification and modification technique significantly reduced the errors in GPS measurements.