Centre county Pennsylvania, USA | Ted, I didn't take your (or Don G's) comments as criticism, greatly appreciate both. You and Don G are right, elevation angle mask should not be applied to WAAS satellite, someday I will test both Trimble and Starfire antennas for that, it's on "to-do" list. WAAS satellite AOR-W is now at 11 degree elevation here and the new WAAS satellite (PRN 135) is at 17 degrees elevation but it's not in Trimble WAAS setup menu (yet). Hopefully we will get version 3.2 firmware upgrade, soon.
I think setting elevation mask angle is kind of a black art. If you set it too high then Dilution Of Precision (DOP) is high (lousy) because satellite numbers decrease and satellites are not "spread" enough to give good geometric coverage. If you set it too low then multipath and atmospheric distortions can significantly reduce GPS accuracy. I usually set elevation mask for about 12 degrees. When we run on hills (almost always) tractor tilt and pitch is often high so that would mean that WAAS satellite at 11 degree elevation would be seeing back side of GPS antenna when tractor was tilted or rolled more than 11 degrees. I'm not sure if WAAS signal can get in from back side of antenna ? |
Waas
