3 ms·
Yes, lasers. Even with the higher accuracy and more expensive real time dGPS systems the vertical accuracy isn't as good as horizontal. When you're looking for
by mutagen 11y ago
Yes, lasers. Even with the higher accuracy and more expensive real time dGPS systems the vertical accuracy isn't as good as horizontal. When you're looking for a very shallow gradient in a field for irrigation GPS just isn't as good as a laser level.
Much of the problem is geometry, while you're likely to have a good spread of satellites around your receiver horizontally they're all on one side of the vertical solution your receiver is calculating.
- trimble-alum 11y ago3 sats are needed for a two point fix, 4 for a one point fix, and 5+ help with accuracy if they're not clumped near each other (the constellation's always moving). At higher altitudes such as in a plane at FL 350 with sats below the receiver, vertical accuracy increases some compared to ground, which makes these obvious: http://www.gps.gov/applications/space/ http://www.gps.gov/applications/space/