Re: [amsat-bb] Leap Second caution

Rick Walter (
Sat, 2 Jan 1999 19:42:28 -0500 (EST)

Hi Jim.  I have the Radio Shack "Atomic Clock" and it has been right on
since they first started selling them.  I watched my clock on New Year's
Eve, and it updated correctly with the leap second added.  It has been
right on ever since.  The Radio Shack clock updates at 9:00 PM local time.
Since the extra second was added at 6:59:59 PM, local time (Eastern
Standard) on December 31, I watched at 9:00 PM local and the leap second
was added correctly.

I went outside to watch my GPS receiver's time and it already had the leap
second added before 6:59:59 PM local (0 hours UTC).  I'm not sure when
that change occurred.  I have the Garman 45XL. Maybe the clock on the GPS
receiver does not really come from the satellite's atomic clock?

Did you notice most of the television shows counting down to the new year
did not have the correct time due to the leap second?  They were all a
second too fast! Also, I know many "accurate time" TV and radio stations
are usually off a few seconds.  I've seen the weather channel be off by as
much as 15 seconds.  That time may be generated locally, with the local
forecast clock?

Rick, WB3CSY

On Sat, 2 Jan 1999, Jim S wrote:

> A word of caution from personal experience for those of you using the new 
> "atomic" clocks to obtain accurate time for your satellite listening 
> and/or viewing pleasure.
> These clocks receive radio transmissions from WWVB to initially set and 
> periodically update themselves, applying an error correction to adjust or 
> fine-tune the internal time-base.
> The addition of a "leap-second" on January first confuses the clock into 
> adjusting for the apparent one-second error by making an unwanted 
> adjustment of the time-base rate.  If left alone, this should 
> automatically re-adjust itself back to a correct value over an extended 
> period of time.  In the interim, clock accuracy suffers.  If in doubt, 
> the clock should have a "reset" button hidden away somewhere which will 
> force the processor to return to default and start over.
> I was impatient and forced a reset so I cannot guess as to how long an 
> automatic resync would take.  I can say that the effects of the 
> leap-second adjustment were quickly apparent when compared to another 
> clock with only manual adjustment.
> Happy New Year!     ;)
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