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Tipton, KS | Technical Sidebar
One network station in Australia (1), when examining XYZ coordinates (2), their coordinates vary
X: 21mm
Y: 21 mm
Z: 45 mm
when using a Trimble antenna (3). Trimble's graphs show mm differences as a function of a satellite's elevation. When doing an OPUS evaluation, these differences are used to account for tracking offsets (phase center offsets).
In the GNSS antenna calibration database (4), the offset information has been certified, for instance, a different antenna listed as Harxon CGX611A (5), and the manufacturer has to pay to have this done. For antennas listed in this database, retail prices range from modest to very high prices.
Upshot - A GPS antenna for better/precise coordinates must be listed in this database when using a decent/excellent receiver. Otherwise, phase center offsets can not be accounted for when doing an OPUS evaluation.
1. https://www.spatial.nsw.gov.au/surveying/corsnet-nsw/network_informa...
2. https://www.spatial.nsw.gov.au/__data/assets/pdf_file/0007/197818/IR...
3, https://trimbletools.com/Antenna_Info/IGS14/TRM55971.00_____NONE.htm...
4. https://www.ngs.noaa.gov/ANTCAL/#
5. https://www.terrisgps.com/wp-content/uploads/2021/08/harxon-cgx611a-... | |
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AG25: OPUS How To
