[time-nuts] Leap second glitches on NTP using Z3801A

[Brooke Clarke]

Hi Eric:

The GPS time scale can not have any jumps or there would be corresponding 
position jumps.

Have Fun,

Brooke Clarke
http://www.prc68.com

Eric Garner wrote:
> Sorry for not forming my question better. I guess what I wanted to
> know is that given that the first leap second was in 1972 and that the
> first GPS satellite was launched in 1993. why was it decided to not
> incorporate leap seconds into how GPS "tells" time, but still alerts
> you to the fact that they are coming up? Or why was the decision made
> to have UTC-GPS different than UTC. My understanding is that they
> "tick" simultaneously but "tell" different times.(sorry for the
> overuse of quotes)  Is there some navigational reason? Is it actually
> intentional?
> 
> -eric
> 
> On Sun, Nov 16, 2008 at 8:08 PM, Brooke Clarke <brooke at pacific.net> wrote:
>> Hi Eric:
>>
>> So that you can figure out UTC.  But there's no DST bit on any of the
>> satellites so for that you need a local time broadcast.
>>
>>
>> Have Fun,
>>
>> Brooke Clarke
>> http://www.prc68.com
>>
>> Eric Garner wrote:
>>> Ascending from Lurk Mode, I have a (possibly stupid) question: according to
>>>
>>> http://tycho.usno.navy.mil/leapsec.html
>>>
>>> and Tony Jones's book "The Story of Atomic Time" GPS time does not
>>> account for leap seconds, So why does it alert you to them?
>>>
>>> -eric
>>>
>>> On Sun, Nov 16, 2008 at 7:21 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>>>> Is anybody running ntpd with their Z3801A?
>>>>
>>>> If so, please check your log files and tell me if you see a bogus leap second
>>>> at the end of the past several months.  I've seen them for Aug, Sep, and Oct.
>>>>  I think they are coming from my Z3801A, but it might be something else.
>>>>
>>>> The GPS satellites are now announcing a leap second that will happen at the
>>>> end of the year.   The refclock driver passes that to ntpd and ntpd passes it
>>>> to the kernel and magic happens.
>>>>
>>>> I think the refclock-ntpd interface assumes the leap second will happen at
>>>> the end of the current month.  NIST only announces leap seconds a month ahead
>>>> on WWVB and ACTS.
>>>>
>>>> The Oncore refclock driver has a filter to wait until the current month to
>>>> pass the info to ntpd.  I'm working on something similar for the HP driver.
>>>>
>>>> --
>>>> These are my opinions, not necessarily my employer's.  I hate spam.
>>>>
>>>>
>>>>
>>>>
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>>>
>>>
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> 
> 
>