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Cedar Rapids, Iowa | Overall, OmniStar XP/HP did seem to be a bit more stable than SF2, but the amount was marginal, certainly not a factor of 3. They're close enough that I doubt most people could tell the difference in the dirt.
Receiver manufacturers are continually looking for ways to improve the accuracy of their systems. For example, NovAtel has developed an algorithm called GLIDE that does ionosphere modeling in the receiver to smooth the drift. It was originally developed for use in South America to achieve autonomous performance at a level similar to WAAS as they don't have anything like WAAS available for free in that region. However, here in North America, it can also be used with WAAS, which approximately cuts the drift in half.
The Trimble receivers that include the SBAS satellite in the solution (a good idea) means you get one extra satellite to get a distance from. This helps a bit when working around trees and stuff. The SBAS satellites only broadcast on the L1 frequency, which is all WAAS uses anyway, so it helps that solution. When you go up to a dual frequency solution (SF1/SF2, OmniStar XP/HP), then you really want all the satellites to provide both frequencies, thus making that L1-only SBAS signal not as useful.
We have a tillage tractor on WAAS this fall via a Trimble 750, and it has some days where it drifts all over the place. I think the level of solar activity has a greater effect on the performance than what the software improvements have been able to improve. Also, as Trimble now owns OmniStar, I wonder if there is a financial incentive to not improve performance on WAAS.
-Lance | |
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Accuracy of Deere's SF1 vs. Ag Leader using WASS
