Hi Chuck,

Thanks for the comprehensive list. Very nice work. This bug in many versions of 
the HP SmartClock-series has shown up before (but not always in the 90's, see 
below). What's going is yet another problem with how developers write code for 
leap seconds. It's really hard to get right.

There is a distinction between when leap seconds are *announced*, usually 2 to 
6 months in advance (somewhat variable, almost random) and the month in which a 
leap second actually *occurs* (a very specific instant).

Unfortunately, the word "pending" is ambiguous since it does not distinguish 
between the casual advising that a leap second will occur many months in the 
future and the actual month in which the leap second occurs. This leads to both 
human and technical confusion.

In addition, there is confusion about when a leap second *can* occur. The UTC 
specification implies a leap second may occur at the end of any month, although 
it is most likely the 6th or 12th month, and if not that, the 3rd and 9th 
month. Some vendors have misinterpreted this to mean, for example, that if a 
leap second is announced in January it will therefore occur in March (rather 
than June). Oops.

These are difficult bugs to fix. For most of the 70's, 80's and 90's leap 
seconds were announced only a few months ahead of time. But in the past decade, 
IERS had been able to predict leap seconds almost 6 months in advance -- and 
this exposes bugs in software that used to work just fine.

/tvb
  ----- Original Message ----- 
  From: Charles Zabilski 
  To: Tom Van Baak 
  Sent: Saturday, January 24, 2015 9:47 AM
  Subject: 2015 Leap Second


  Tom:


  Unfortunately I no longer receiver emails from time nuts due to my @yahoo.com 
email address.  In response to your desire to pull together a list of GPS 
receivers' handling of the upcoming leap second, please see the following:


  Receiver        1st Reported date        Reported Leap Sec Date
  Z3801A               22 Jan 2015                    31 Mar 2015
  Z3811A               22 Jan 2015                    31 Mar 2015
  Z3816A               22 Jan 2015                    31 Mar 2015
  58503A               22 Jan 2015                    31 Mar 2015
  58503B               22 Jan 2015                    31 Mar 2015
  59551A               22 Jan 2015                    31 Mar 2015


  Z3805A               No Leap Second Indication
  Z3815A               No Leap Second Indication


  Please note that I usually only check for the leap second notifications in 
the mornings.  In all probability the notifications occurred some hours 
earlier.  Also, I am communicating with the GPS receivers through the external 
Com port using my GPS Control Program and not examining the internal GPS module 
data stream.


  I hope this is of some assistance.


  Chuck Zabilski
  BD Systems, Inc.
  Evergreen, CO
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