iGage iG9 User Manual
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These stations and all the others like them are unsuitable for any processing use. It is your
responsibility to exclude them from your solutions.
#8 GPS Suitable Locations
The NGS recommends that you submit GPS occupations collected in GPS suitable locations.
Ho
wever, very little NGS guidance is provided for what is ‘GPS suitable’ in the context of OPUS
submissions. Let’s compare good and bad locations.
Best Case Scenario
The best possible site would have a totally clear view of the sky above 10° at all azimuths where
there is a possibility of a GPS satellite being in the sky:
Obstructions to the North not important in North America
Note: OPUS will process observations down to 10° elevation so you should set your receiver to start
tracking a few degrees below 10°, or just allow it to track all the way to the horizon (0 degrees
Elevation Mask.)
Attributes of a great GPS location for collection OPUS ready occupations:
No overhead power lines
No trees: leaves on or leaves off
No power poles (wood or metal)
