[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 


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