The Influence of Malaysian Troposphere on the Performance of Satellite-Based Positioning System

Abstract- GPS is the only fully-operational satellite-based positioning system currently available to all-inclusive users at no direct charge. Triggered by the value-added functionality and the innovative field operation interoperability brought by satellite positioning and navigation systems, GPS has been widely used by professionals and practitioners to address diverse applications such as navigation, surveying, mapping and engineering purposes. GPS utilizes the time-of-arrival (TOA) ranging concept based on the satellite-to-receiver signal transmission to determine one position. Apparently, the key limitations currently facing this multi-satellites system is the latency of signal arrival caused by the effect of troposphere where most of the world's weather takes place. The effect is much more pronounced in Malaysia as it is located at the equatorial region where the troposphere extends the most above the earth surface in comparison to any other region. High humidity climate caused by the spatial and temporal variability of water vapour content within the troposphere exaggerates the signal propagation effect even further thus affecting the accuracy of GPS derived positions. Result shows that by neglecting the use of tropospheric a priori model, maximum residuals in Easting, Northing and Height components due to tropospheric effect are 68.880 cm, 68.970 cm and 119.100 cm respectively. Similarly, reaching to the minimum and maximum RMS value of 16.8 and 29.2 respectively, GPS Height component is by far the most affected component compared to the Horizontal components. In most cases, the result also reveals that tropospheric error is a distance dependant error that increases with the increases in the baseline length between two stations. I