Centre county Pennsylvania, USA | Attached position error plots are from data logged during on-farm tests of EZGuide-500/WAAS static scatter on Jul 14 and Jul 15 2008. Tractor was parked at different locations for each test, locations were separated by several thousand feet. EzGuide-500 was configured to use SBAS (WAAS) satellites 135 and 138 in position solutions and OnPath filter was set for "some trees and buildings". Tests started after moving tractor to test location and EZ-Guide-500 began reporting use of WAAS iono model. Number of satellites tracked was 10 or greater, and HDOP was below 1.3 during all tests.
The test graphics for both days show that it takes 15 to 20 minutes for static position errors to "converge" to the low (steady state) range that is quoted for EZ_Guide/WAAS position accuracy. That's in addition to the time it takes to get WAAS iono model. I'm not sure if those test results mean anything, but we here will assume the tests mean that we should allow EZ-Guide 500 an additional 15 to 20 minutes, after it reports use of WAAS iono model, to "converge" before we engage EZ Steer.
 (EZ500 static position error, test Jul 14 08.JPG)
 (EZ500 static position error test Jul 15 08.JPG)
Attachments
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 EZ500 static position error, test Jul 14 08.JPG (42KB - 136 downloads)
EZ500 static position error test Jul 15 08.JPG (49KB - 144 downloads)
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EZGuide 500/WAAS static convergence behavior
