[time-nuts] June 30 2015 leap second

Chuck Harris cfharris at erols.com
Sun Jan 11 15:02:15 EST 2015

I don't know for sure which category the Ball/Efratom MGPS
(as found in the MFS-XXX Modular Frequency Standard frames) is
in yet.... But the MGPS has a screen labeled "Current Leap Second",
that according to the manual:

"The display indicates the date and time of the current leap second.
  Leap second data are hourly updated by GPS satellite transmission

  A leap second can also be programed by the operator.  To program a
  leap second date and time, it is first necessary to select the
  Edit menu by pressing the pushbutton "E"...."

I had to remove the lithium cell from my unit when I was servicing
it, so it is now displaying some hard reset default value:

Date 17 05 27  Time 23:59:00

If the "Current Leap Second" is indeed updated hourly, and my
display persists in showing a nonsense value, I am wondering if it
might be that it thinks it is in a manually programmed leap second

Perhaps I should manually program it to: 00 00 00 00:00:00,
and, hope it will get the clue that it is supposed to automagically
update the Current Leap Second from the GPS packets?

I would hate for my MGPS to miss the leap second party because the
manual was unclear.

-Chuck Harris

Tom Van Baak wrote:
>>> I haven't looked at the raw data, but using the windows apps: a Trimble
>>> Resolution SMT is showing the leap pending a Motorola UT+ is not. lady heather
>>> is not
>> Interesting.  I don't see any leap-pending from a Z3801A.  (or a KS-24361)
> Hi Hal,
> It's not that simple. There are many different levels of leap second
> notification.
> 1) IERS updates their ftp site (for bots) and sends email (for humans) indicating
> when the next leap second will occur. Days or weeks (and sometimes months) later,
> 2) GPS ground control uploads almanac information to the satellites with updated
> UTC parameters. Four values in page 18 of subframe 4 give the current UTC leap
> second delta and also an optional future UTC delta, with a GPS week (LS_f) and day
> number (DN) when that future delta will be current. By definition the leap second
> will occur at the end of a UTC (not GPS) day.

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