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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
GPS Time
From: Dan Allen
Date: 1999 Mar 15, 14:38 EST
From: Dan Allen
Date: 1999 Mar 15, 14:38 EST
With my old Garmin GPS 40 I noticed that occasionally the displayed time on my GPS was up to 1.5 seconds off of WWV. More recent Garmin receivers seem to be better. One other potential "gotcha" with GPS receivers: until the satellites are locked on, the displayed time may be WAY off. The built-in clock is terrible. I guess Garmin assumes you will always have the satellites around, but before lock on I have seen the displayed time off as much as a MINUTE or more (especially if the GPS has been sitting unused for a few months). Once the 3rd satellite appears, then the time jumps to the "real" time. We need more accurate clocks available. A few watch manufacturers in the 1980s made "Twin-Quartz" watches (Seiko Lasalle and Omega) which were thermally compensated and would not be off a single second in a year. If they were off from WWV, it was usually because a leap-second had been inserted! Alas, I do not own either watch (a friend has had these), but I wish somebody would make a twin-quartz chronometer again with ultra accurate time. Dan -----Original Message----- From: Richard Langley [mailto:lang@XXX.XXX] Sent: Monday, March 15, 1999 5:34 AM To: Rick Emerson Cc: navigation@XXX.XXX Subject: Re: FW: [Nml] 249 v 229 , Starpath, time tick P.S. The time indicated by a GPS receiver on its screen may be a fraction of a second delayed due to receiver microcomputer task scheduling. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-= =-= TO UNSUBSCRIBE, send this message to majordomo@XXX.XXX: =-= =-= navigation =-= =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=