EVALUATION OF THE EFFECT OF VARYING GLOBAL POSITIONING SYSTEM (GPS) SIGNAL POWER LEVELS ON GPS ACCURACY.

In this study, Global Positioning System (GPS) simulation is used to evaluate the effect of varying GPS signal power levels on the accuracy of two handheld GPS receivers; Garmin GPSmap 60CSx (evaluated GPS receiver) and Garmin GPSmap 60CS (reference GPS receiver). Both receivers employ the GPS L1 coarse acquisition (C/A) signal. With decreasing GPS signal power level, probable error values increase due to decreasing carrier-to-noise density (C/N₀ levels for GPS satellites tracked by the receiver. Varying probable error patterns are observed for readings taken at different locations and times. This is due to the GPS satellite constellation being dynamic, causing varying GPS satellite geometry over location and time, resulting in GPS accuracy being location / time dependent. For all the readings taken, the evaluated GPS receiver recorded lower probable error values as compared to the reference GPS receiver. This occurred as the evaluated GPS receiver has higher receiver sensitivity, and hence, is able to obtain lower position dilution of precision (PDOP) values. In addition, it has lower receiver noise, reducing the value of its user equivalent ranging error (UERE). [ABSTRACT FROM AUTHOR]