[LEAPSECS] Local insertion of leap seconds

[Stephen Scott]

Subject: Local insertion of leap seconds

I am new to this group so please excuse if this subject has been 
previously covered.

As I understand the standard ITU-R TF.460-6 the leap second correction 
is instantiated globally as the last second of a UTCZ month.

However I have not been able to determine any practices for 
instantiating the leap second correction at other times to avoid such an 
interruption in the timescale at an inopportune time of day in different 
locations around the world.

In countries west of Greenwich the insertion happens before midnight 
making possible to delay the correction to a later and more appropriate 
time. However in countries east of Greenwich the correction could need 
to have sufficient advance notice.

Can you enlighten my understanding of what practices may exist?

Background for these concerns is compounded by a number of factors.

1.)Television broadcast automation requires precise timing to avoid 
programs and in particular commercials from being clipped or having gaps.

2.)Video in North America and some other parts of the world is generated 
on a timescale that is at a frequency of 30/1.001 Hz. This deviation 
from a SI second timescale means that a leap second insertion is 
equivalent to inserting 29.97002997... video frames.

3.)This rate implies in a non-integer number of video frames in a 24 
hour day and thus a varying phase alignment to a 24 hour clock.


Regards
Stephen

-- 

*Stephen Scott*

Skotel Corporation
Brossard, Québec

Canada

Mobile: +1 514-806-2340

Skype: SScott2645

Email: stephenscott at videotron.ca



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