A Simulation Study on Triple Frequency Ambiguity Resolution for Reference Stations Using Different Strategy Regarding Elevation angles

This paper proposes an ambiguity resolution method using triple frequency for reference stations. Using the reference coordinate information, geometry based ambiguity resolution performance is analysed. Although orbit errors and tropospheric model errors still remain, wide lane ambiguity could be fixed in several epochs. However, the narrow lane wave length of about 10cm is too short to overcome error sources by simply combining the measurement. Therefore, we have divided the elevation angle into 5 degree intervals and investigated the measurement errors and the time to fix of each section. For high elevation satellites, it is possible to determine in several epochs by integer rounding. On the other hand, if the elevation is lower than 30 degrees, the tropospheric zenith delay must be estimated with ambiguities. The proposed algorithm estimates ambiguities and tropospheric zenith delay simultaneously utilizing ambiguity free observations of high elevation satellites. Ambiguities for high elevation satellites are resolved by integer rounding in several epochs. The algorithm has been verified by generating the simulated observation data for the ‘Cheon-an’ and ‘Boen’ reference stations in the Korea.

Analysis of Regional Distribution and Change of Tropospheric Delay

In this article, data of stations distributed over China was used to calculate tropospheric delay. The result was compared with the tropospheric zenith delay calculated from model. The rules and Characteristic of tropospheric delay over China was analyzed from the aspect of altitude, climate, and change. The results showed that the tropospheric zenith total delay decreased from the coast to the central and western regions, the Tibetan plateau is minimum. Zenith wet delays computed from the models also show an absolute bias of over 20 mm with respect to that of sounding data. The standard deviation is more than 30 mm in the tropical monsoon zone.