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 15, 11:25 -0700
From: Lu Abel
Date: 2009 Sep 15, 11:25 -0700
Antoine: If aircraft cockpit displays are showing the wrong time, I would suspect it's due to the same problem (delay in processing and updating time information) that started this discussion rather than their displaying GPS time instead of UTC. As Richard pointed out, the GPS to UTC correction factor is broadcast by the satellites, so there's no reason that a GPS receiver can not accurately display UTC (with the possible exception of a period of time after a cold start, as Richard points out). Lu antoine.m.couette@club-internet.fr wrote: > Dear Richard and Lu, > > > True, you did pick it right, I should have written UTC also ! > > Thank you for your interesting insight on all the data displayed in the GPS message ! > > Since in civilian A/C, the cockpit watches are often directly fed by the on-board GPS receiver (uncorrected to UTC to the best of my knowledge : at least this is what I have noticed on the DC10-30's and B757/767's I have flown while watching increasing differences between GPS time and UT over the elapsing years) I was not aware of all the nice features which are part of the GPS messages, including advance notice about the upcoming leap seconds. > > Thank you again, and hello to the Navlist Forum > > > Antoine > > > Antoine M. Couette > > > > > --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---