Estimating Accuracy of GPS Doppler Speed Measurement using Speed Dilution of Precision (SDOP) parameter

This article presents a method for estimating the accuracy of GPS-Doppler speed measurement using Speed Dilution of Precision (SDOP) parameters newly introduced by SiRF. Direct measurements of GPS-Doppler speed errors are confronted with theoretical SDOP predictions. Comparison reveals that SDOP is a very useful and practical parameter for determining accuracy of GPS-Doppler speed measurement. It is demonstrated that 10-second average speed can be measured with accuracy better than 5 cm/s and confidence better than 99.9% using GT31 logger equipped with SiRF3 chipset.