engleski

Estimation of MOPS/EGNOS Tropospheric Delay Model Accuracy at northern and southern Latitudes

Some fundamental limitations on positioning accuracy using satellite navigation technique require serious consideration and mitigation. GPS signals change the propagation speed and direction as they pass through the earth's atmosphere on their path from the satellites to the receiver. Troposphere affects electromagnetic signal propagation causing signal path bending and the alteration of the electromagnetic wave velocity. Tropospheric delay can introduce considerable error in satellite positioning, if it is not properly estimated. Two basic types of delay prediction models exist. The tropospheric models of the first type use surface meteorological parameters to estimate the magnitude of the tropospheric delay. The other so called "navigation-type" models do not require real-time meteorological input and use average and seasonal variation data. To verify the accuracy of tropospheric delay models, we compared representatives of both types within a period of 12 month, comprising all seasons. We noticed that the seasonal variation of the tropospheric delay over the one-year period using modelling with meteorological parameters shows much better conformance with the MOPS (Minimum Operational Performance Standards for GPS)/EGNOS model at northern latitudes than at southern part of the earth. This motivated us to further analyse the MOPS/EGNOS model, which presumes the symmetry of the tropospheric delay values on northern and southern part of the earth at similar latitudes and suggest some modifications of it.

Tropospheric delay; Saastamoinen model; MOPS/EGNOS model

nije evidentirano