Gps Measurement Precision Of The Study And Application

The application of velocity measurement, just like position measurement, is very extensive area. Traditional method of velocity measurement is mainly used by Doppler frequency shift and laser. But now the Global Positioning System (GPS) becomes a crucial tool of measuring velocity. GPS, because of all-weather and global, continuous, highly accurate, and other characteristics, rapidly becomes a mainstream means of the positioning and navigation tool. GPS not only determine the real-time the 3D position in real-time, but also provides the instantaneous velocity vector. Unfortunately, the velocity measurement with GPS is not popular as that of position measurement.This paper firstly summarizes the development of Global Navigation Satellite System (GNSS) and the research status in the velocity measurement with GPS. Then the methods and mathematical models of determining velocity with GPS are detailedly introduced. Thirdly, the velocity measurements from DGPS, RTK-GPS and single point positioning, both in static and dynamic status, are analyzed and discussed. Fourthly, the several GPS error sources affected velocity measurement are discussed, and the two methods limited the random noise are suggested. Finally ADCP current meter detection application is introduced.The velocity measurement contains a lot of random noise. In order to minimize the noise impact, the Chebyshev polynomials is suggested to smooth the static speed data, as well as the Uscented Kalman Filtering is proposed to filter the dynamic velocity measurements. The results show that the accuracy of GPS velocity measurement is obviously improved after smoothing and filtering.