On Friday, March 09, 2007 1:33 AM [GMT+1=CET], Iain Street <[EMAIL PROTECTED]> wrote:
> ----- Original Message ----- > From: "Tony Brooks" <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Thursday, March 08, 2007 12:33 PM > Subject: [canals-list] Re: Boat trouble with GPS positioning > > > (snip) >> God help anyone who flys! >> >> My GPS has the Leicester arm sumit going up and down by about 100ft - >> could maake intersting landings :-) >> > > I find the height to be the most inaccurate part of GPS on the ground. > However, height derivation requires at least 4 satellites, preferably > as far apart as possible, and all the signals will be affected to > some extent by reflections from nearby objects, including the ground. > I would expect a much better performance when clear of all obstacles, > and a 360 x >180 degree horizon.
