[time-nuts] June 30 2015 leap second

Martin Burnicki martin.burnicki at burnicki.net
Tue Jan 13 03:46:53 EST 2015


d0ct0r wrote:
> Today, I did the check the settings for my BC637 card. I was surprised
> that its overwrite my manual setting for the Leap Event by following
> information:
>
> Time Settings:
>
>   Mode                           : GPS
>   Time Format                    : Binary
>   Year                           : 1995
>   Local Offset                   : 0.0
>   Propagation Delay              : 0
>   Current Leap Seconds           : 16
>   Scheduled Leap Event Time      : 876614400
>   Scheduled Leap Event Flag      : Insertion
>   GPS Time Format                : UTC Format
>   IEEE Daylight Savings Flag     : Enable
>

Why are you wondering? This should be the expected result if your card 
receives and decodes the data from the GPS satellites.

> "Sun, 12 Oct 1997 00:00:00 GMT". Its weird. I am going to re-insert it
> and will check it again later.
>
> New Time Settings are:
>
>   Mode                           : GPS
>   Time Format                    : Binary
>   Year                           : 2015
>   Local Offset                   : 0.0
>   Propagation Delay              : 0
>   Current Leap Seconds           : 16
>   Scheduled Leap Event Time      : 1435708799
>   Scheduled Leap Event Flag      : Insertion
>   GPS Time Format                : UTC Format
>   IEEE Daylight Savings Flag     : Enable

I'd expect these will be overwritten again during GPS reception.

However, as far as I can see the UTC parameters currently sent by the 
satellites still haven't been updated to reflect the upcoming leap 
second, so the date derived from the old week number in this parameter 
set is ambiguous. Also the event flag (insertion vs. deletion) can't be 
determined from the curent parameters. I'd expect that this is just an 
interpreting problem in the user interface.

> Also, my NTP, which rely on that card,  didn't get the value for leap
> second event yet:
>
> # ntpq -c rv
>
> associd=0 status=0028 leap_none, sync_unspec, 2 events, no_sys_peer,
> version="ntpd 4.2.6p5 at 1.2349 Mon Sep 22 20:41:39 UTC 2014 (14)",
> processor="x86_64", system="Linux/3.2.0-74-generic", leap=00, stratum=1,
> precision=-23, rootdelay=0.000, rootdisp=8248.907, refid=BTFP,
> reftime=d85e7526.957a1b17  Mon, Jan 12 2015 11:30:30.583,
> clock=d85ec544.e1effe31  Mon, Jan 12 2015 17:12:20.882, peer=0, tc=4,
> mintc=3, offset=3.757, frequency=-243.698, sys_jitter=0.000,
> clk_jitter=1.328, clk_wander=15.616

What would you expect to see? Ntpd accepts and forwards leap second 
announcements only one day before the leap second event.

If ntpd would accept a leap second warning right now and set the "leap" 
variable accordingly then all its NTP clients would try to insert a leap 
second at the end of January. I don't think this is what you want.

By the way, are you sure the driver /127.127.x.0) you are using to let 
ntpd get the time from your PCI card supports passing on the leap second 
warning to ntpd?

Martin



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