Posted 5/22/2006 01:21 (#13905 - in reply to #13741) Subject: RE: USCG DGPS service accuracy ?
The accuracy advantage of beacon (this changes with the distance to the beacon) over waas is not the reason I will not buy a guidance system without beacon correction. I have come to the conclusion that I am one of the few end users on this site that has experienced the problems caused by extended high solar activity. Our first guidance unit, a 132 Trimble was purchased in Dec 1998, had repeated and unpredictable accuracy problems that started while the unit was still under warranty. One time the off-track error moved 18 ft in about 5 min with the spreader stopped. This was with OmniStar correction. OmniStar said nothing was wrong, and Trimble was evasive. Repeated calls to both got no answers untill I tried to make Trimble take the unit back. I was instructed to switch to beacon correction. Problems solved. Solar flares, sunspots, etc created radiation surges that gps and OmniStar could not handle. The beacon was shielded by the atmosphere and its close location allowed good correction. Waas did not exist then, but someone I trust at Trimble recently told me that the problem has not been solved and waas will have similar, but slightly lesser problems than OmniStar. I think the solar activity peaked in 2001 and has a cycle of 11 years. Right now is about as good as it will ever get, the problem will start back up in a few years and peak in 2012. Since I intend to be using guidance systems then, a beacon capable receiver is a requirement.