[time-nuts] June 30 2015 leap second

d0ct0r time at patoka.org
Tue Jan 6 16:01:25 EST 2015


As I am in the process of creation of my own Nixie clocks. And it 
probably good time frame to clarify one thing about leap seconds. In my 
project I am using GPS module as an option to have current UTC time and 
also to have 1PPS signal to do auto-adjustment for external RTC module. 
The question is how usually GPS modules handle leap seconds ? Is it 
satelates who send UTC time to GPS module or GPS module has firmware 
with leap second information hard-coded ?
The same question is for UNIX epoch time. How computers knows if it is 
necessary to add leap seconds ? Lets say I am using very simple script 
to calculate UNIX time for specified date:


use Time::Local;
my ($d, $m, $y);
my $time;

@myYears = ('01/06/2000', '01/06/2015', '01/06/2038', '01/06/3000');

foreach (@myYears) {
         ($d, $m, $y) = split '/', $_;
         $time = timelocal(0,0,0,$d,$m-1,$y);
         printf "%ld\n\r", $time;


It will produce the following output:


I am not sure if its take leap second consideration. Most likely not. 
And that means its only accurate for the present and pas time. Right ? 
For my clock I already implement the function for the leap second and I 
am able to add/remove number of seconds from the time I receiving from 
GPS or any other source. But it will be more inetersting if clock could 
do it "automagically" and shows me that famous "60" number without human 
interaction. Any advise for this ? Thanks !



On , Tom Van Baak wrote:
> Just announced: there will be a positive leap second at the end of
> June 30 2015 UTC (that's Wednesday July 1st for most of the world).
> As usual we time nuts will have a leap second party -- where we
> capture and share the magic hh:59:60 display on as many different
> clocks and instruments as possible.
> /tvb
> More info:
> ftp://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat
> http://hpiers.obspm.fr/eop-pc/
> And for those of you who want to know how long each day really is:
> ftp://hpiers.obspm.fr/iers/bul/bulb_new/bulletinb.dat
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