[ntp:questions] Re: List of time synchronization hardware and software

John Ackermann N8UR jra at febo.com
Tue Jan 17 18:57:54 UTC 2006


David L. Mills wrote:
> Rob,
> 
> I can confirm that the Spectracom GPS and WWVB receivers, Arbiter GPS 
> receiver, TrueTime NTS-200 GPS/NTP server, WWV/H audio driver and those 
> systems with the NIST leapsecond file, either via ftp or Autokey, 
> handled the lurch correctly. On the other hand, the EndRun CDMA/NTP 
> server took about five minutes to lurch.
> 
> Dave

My Spectracom 8170 did *not* handle the leapsecond correctly, and a 
reading of the manual after the fact indicates that it wasn't meant to:

"Once the Time Sync light is on the clock will keep UTC time. The 
display will be changed when 3 consecutive good compares are received 
that do not agree with the display data. This will happen when the leap 
second is inserted."


It updated by holding for a second at 00:03:59.

The algorithm apparently ignores the leapsecond flag in the timecode, 
and works as follows: at 00:01:00, WWVB tells the clock that it is a 
second fast.  At 00:02:00 and 00:03:00 that is confirmed.  The display 
updates at 00:03:59.

I'm not sure why it waited until the end of the third minute, rather 
than the beginning, to make the change, but that's what happened. 
(timestamp extract at the bottom of 
http://www.febo.com/time-freq/leapsecond-2005/index.html).

John



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