Master Station Position

When loading a master station, the coordinates that appear in the master coordinate dialog may come from two different sources.

If loading data converted from RINEX, as is the case when obtaining base station data through the Download Service Data Utility, the coordinates that appear initially are scanned from the RINEX header. The coordinates provided in the RINEX header may be precise or approximate, this will depend on the individual RINEX data provider. The RINEX header does not provide any information regarding the datum of the coordinates. As such, the user is required to specify the coordinate datum of each base station loaded.

If loading base station data converted from any other source, the coordinates that appear initially are likely averaged from the unprocessed position records decoded in the raw GNSS data file. The accuracy of this position is typically no better than approximately 2 m horizontal and 5 m vertical. If you select the OK button using averaged coordinates, a warning dialog appears to ensure you are aware the coordinates may not be accurate.

Regardless of the source of your base station data, it is important that accurate coordinates are loaded. In differential processing, a vector is solved between the base station antenna and the remote antenna. Any error in the base station position is directly transmitted to the remote position.

To assist in loading precise coordinates, it is recommended that coordinates be selected from the favorites list through the Select from Favorites option, which appears under the Coord. options pull-down. Coordinates for select base station networks, such as CORS and IGN, are regularly maintained and accessible through Favorites.

The Compute from PPP option, which also appears under the Coord. options pull-down, can be used to easily check or survey base station data using the Precise Point Processor. When using this option, the differences between the loaded and computed coordinates are displayed. If the master station has a NovAtel receiver and the user has an NRT subscription, PPP-AR will be used. Note that PPP accuracy is largely dependent on the length of the survey and the quality of the data.