By: Derek Shalla, Precision & Equipment Sales
This spring was a challenge unlike most others due to unseasonably cold weather that lasted well into the beginning of May. To help further complicate fieldwork, some of you might have had GPS (WAAS) quality issues. This issue affected all manufacturers including most brands we handle (Raven, Ag Leader, TeeJet, Precision Planting, and Topcon). The issue was caused by the FAA decommissioning differential satellite PRN 138 on May 18, 2022. That satellite was important, because it was the most highly used (free/no cost subscription) source of correction in the agriculture industry.
How it works
WAAS is an accurate navigation system that was first developed for civil aviation. Our WAAS system is based off three main components: GPS satellites, differential satellites, and (38) base reference stations across the U.S. There are GPS satellites orbiting Earth all the time, but only a few of them are geostationary satellites (differential). Through computer algorithms, they are continuously triangulating between all three sources which give us accurate GPS coordinates.
What to do
If your GPS antenna is affected, you must either manually change your PRN or choose “automatic” to receive GPS corrections. Since FAA’s decommissioning of satellite PRN 138, they have broadcasted a new differential satellite, PRN 135. For our geographic location, this will be the best differential source to be used in the coming years. I highly advise everyone to take their equipment out and check these settings before fall usage. While most differential source changes can be made through your GPS display, there are older GPS antennas that need a computer program to make the change. I recommend checking those settings now to help eliminate any downtime during fall harvest and fieldwork. When it comes to the brands we carry (Raven, Ag Leader, TeeJet, Precision Planting, and Topcon) we can walk you through switching settings over the phone or if needed, we can make changes with our computer in Hills.