The National Geodetic Survey (NGS) operates the Online Positioning User Service (OPUS) as means to provide the GPS users' with easier access to the National Spatial Reference System (NSRS). OPUS allows the users t...
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The National Geodetic Survey (NGS) operates the Online Positioning User Service (OPUS) as means to provide the GPS users' with easier access to the National Spatial Reference System (NSRS). OPUS allows the users to submit their GPS data files to NGS, where the data are processed to determine position coordinates using the NGS computers and software. OPUS is completely automatic, and the results are e-mailed back to the user, usually within a few minutes. OPUS is intended for the use in the conterminous U.S. and most territories. Currently, OPUS accepts a minimum of two hours of GPS data, with a recommendation of submitting at least four hours in order to obtain the best possible solution (http://***/OPUS/). To extend the number of OPUS users to those, who normally collect shorter data spans, the effort, sponsored by NGS, and performed in collaboration with the Satellite Positioning and Inertial Navigation (SPIN) group at The Ohio State University (OSU), resulted in the development of a rapidstatic module (OPUS-RS), as an extension of the currently used OPUS model. In this paper, the performance analysis of the OPUS-RS module, based on the stations of the CORS (Continuously Operating Reference Station) network is presented. Selected sub-network with ∼250-300 km station separation is used to produce the ionospheric and tropospheric corrections that are tested in the rover positioning solution in multi-baseline mode, simulating the expected reference network and user geometry. One of the CORS stations is considered a user receiver with known coordinates, providing the ground truth to our tests. The data processing is performed in the post-mission mode. Even though the OPUS-RS module is designed to estimate the ionospheric correction internally, additional tests of the positioning module accuracy and reliability were performed using the external ionospheric models. Four external ionospheric models were tested for their accuracy and applicability to support
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