engleski

Constellation switch influence on position accuracy of low-cost GPS receiver

Influence of the satellite constellation change on position accuracy of a stationary stand-alone GPS receiver has been studied. The Lassen LP GPS receiver by Trimble has been used for testing. Measured values of the receiver’ s position have been logged from multiple locations using different receiver parameters: different Kalman’ s filter configurations (2D, 3D, static filter), and different satellite masks (signal strength and elevation angle). The Matlab program was developed for statistical analysis of the position error, for 3D presentation of the results and for development of an expert system for validation of measurement results and low quality data rejection. High repeatability of the position measurement results has been noticed whenever the receiver synchronized with the same satellite constellation. The mean time between satellite constellation changes and the difference in position produced by constellation changing have been measured in order to specify the averaging time required for a given accuracy improvement. We concluded that the least spreading of results is obtained by placing the antenna in a clear sky view position with a low multipath, reducing GPS coverage time by rejecting low-quality results, and by averaging measurement results in the period of at least several hours.

low-cost GPS receiver; constellation switch; multipath; position drift

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