MEASURING GEOCENTRIC RADIAL COORDINATES WITH A NON-FIDUCIAL GPS NETWORK

In this paper we address the problem of estimating the short term prec ision of the geocentric radial coordinate of a GPS receiver placed on the Earth crust using a non-fiducial approach. The network used in our analysis contains 35 receivers distributed globally. We have analyzed the data with two different strategies: global and regional. In the g lobal strategy the results obtained, which are compatible with those o f Heflin et al. (1992) and Blewitt et al, (1992), provide a weighted r oot mean square of the residuals (wrms) one order of magnitude larger than the formal errors of the individual estimates. Our regional strat egy is based on the assumption that errors in the orbit determination induce errors in the receiver positions, correlated up to large scales . This approach allows us to obtain a significant agreement between th e wrms and the formal errors.