[time-nuts] Garmin GPS18 Leap Second Observation

Tom Van Baak tvb at LeapSecond.com
Wed Dec 31 19:26:27 EST 2008

Yes, I think if you dig out the Garmin documentation they
say that's the way they chose to handle leap seconds. It
may be not be "officially" correct; but it's one of several
work-around solutions. If I had to guess, in the NMEA world,
omitting one or repeating a time stamp twice is not as bad
as having a time stamp showing a 61st second. If someone
from Garmin is on the list, please tell us the real reason.


----- Original Message ----- 
From: "Ralph Smith" <ralph at ralphsmith.org>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Wednesday, December 31, 2008 4:06 PM
Subject: [time-nuts] Garmin GPS18 Leap Second Observation

>I was watching the leap second on the NMEA output of my Garmin GPS18,  
> displaying the RNC and GGA sentences.  The GGA sentences repeated  
> 235959, but the RMC sentence repeated 000000.
> $GPRMC,235958,A,3855.4967,N,07723.0144,W,000.0,013.3,311208,010.5,W*7D
> $GPGGA,235958,3855.4967,N,07723.0144,W,1,07,1.9,119.9,M,-33.9,M,,*7C
> $GPRMC,235959,A,3855.4967,N,07723.0144,W,000.0,013.3,311208,010.5,W*7C
> $GPGGA,235959,3855.4967,N,07723.0144,W,1,07,1.9,120.1,M,-33.9,M,,*7F
> $GPRMC,000000,A,3855.4967,N,07723.0144,W,000.0,013.3,311208,010.5,W*7D
> $GPGGA,235959,3855.4967,N,07723.0144,W,1,07,1.9,120.2,M,-33.9,M,,*7C
> $GPRMC,000000,A,3855.4967,N,07723.0144,W,000.0,013.3,010109,010.5,W*7D
> $GPGGA,000000,3855.4967,N,07723.0144,W,1,07,1.9,120.3,M,-33.9,M,,*7C
> $GPRMC,000001,A,3855.4967,N,07723.0144,W,000.0,013.3,010109,010.5,W*7C
> $GPGGA,000001,3855.4967,N,07723.0144,W,1,07,1.9,120.4,M,-33.9,M,,*7A
> Odd.
> Ralph
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