NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: GPS as a time authority
From: Lu Abel
Date: 2009 Sep 14, 20:45 -0700
From: Lu Abel
Date: 2009 Sep 14, 20:45 -0700
The problem with the accuracy of GPS time displays is usually due to the time it takes for them to internally process the data and display it. This can take several seconds (although I've never heard of >5 seconds), especially on older GPS units with non-multichannel receivers and slow microprocessors. All this leads to the GPS display being slow. If anyone on this list has experience with a GPS display being fast, that would be worth noting. JKP@obec.com wrote: > I think this has been dicussed before, but I'd like to be refreshed on the list's opinion: > > While assisting the Race Committee at a regatta this weekend, I heard the timekeepers say that they were using "GPS time." I noted that my $79 wristwatch, which I check monthly against the US Bureau of Standards atomic clock (ph: 303-499-7111) and which doesn't lose a second per month, was 8 seconds ahead of the Committee's time. > > I later checked the time shown on my hand-held Gartmin GPS receiver, and it agreed with my watch. The watch was also still in sync with the Bureau's atomic clock. > > Question: Is the time displayed by GPS receivers considered a reliable and spot-on source, up to the requirements of accurate celnav? I would think that it would be, since the GPS network depends on accurate tracking of the satellites' position at a given time, yet there was that 8-second discrepancy. Perhaps the Race Committee were simply careless about setting theior clockby GPS. > > Any thoughts, List Members? > > -John Parsons > > > > > --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
