NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Da Lurk
From: Jared Sherman
Date: 2003 Feb 10, 13:55 -0500
From: Jared Sherman
Date: 2003 Feb 10, 13:55 -0500
Fred-I suspect that "point" will really be a zone, determined by the EPE accuracy that your GPS is seeing at any time. For instance, when the civilian signal was/is being degraded, you could see your speed and course whipping around all over while you were bolted to concrete. There will always be some "noise" like that behind any GPS operation. If you are moving at 1fps and the system noise is 10fps, your GPS won't be worth reading. But if the reading you get is CONSISTANT then you probably are not looking at noise, you are looking at something real. How real, how valid? That's the naviguesser's job to say "The circle of uncertainty is t h i s b i g today." Since the operation of any computer, including a GPS, is also dependent on how the manufacturer has programmed it, you can't even begin to speculate on this until you refine it to one model of GPS with one set of firmware and find out from the manufacturer what that set will do in those conditions.