The future of UTC
Hi:
There's been talk of a 19 second offset, but it may be 34 seconds, see:
http://hpiers.obspm.fr/eoppc/bul/bulc/UTC-TAI.history
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.End2PartyGovernment.com/
At 02:40 PM 8/10/2011, Brooke Clarke wrote...
There's been talk of a 19 second offset, but it may be 34 seconds,
see:
http://hpiers.obspm.fr/eoppc/bul/bulc/UTC-TAI.history
The mention of "19 seconds" was in relation to GPS time, which is
probably the most widely used source, from which others are obtained
via offset.
GPS - UTC = 15
TAI - GPS = 19
TAI - UTC = 34
On Wed, 10 Aug 2011 16:35:11 +0200
cook michael michael.cook@sfr.fr wrote:
If TAI is a paper clock, what else should be used if a strictly monotone
time scale is needed?
Do you have any specific application in mind?
If you need an SI seconds rated scale, then you need something based on
TAI. GPS time has a TAI second rate and is monotonic. But of course you
would need a GPS receiver to access it.
I don't have a specific application in mind. Just a general question
on what should be used. But lets say i want to have a monotonic clock
for a computer system to timestamp events precisely and unambigously.
Yes, using GPS time (with or without going back to TAI) would be
a probable solution.
Are there any other time scales available that would fit that need?
Attila Kinali
--
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin
Le 11/08/2011 08:57, Attila Kinali a écrit :
On Wed, 10 Aug 2011 16:35:11 +0200
cook michaelmichael.cook@sfr.fr wrote:
If TAI is a paper clock, what else should be used if a strictly monotone
time scale is needed?
Do you have any specific application in mind?
If you need an SI seconds rated scale, then you need something based on
TAI. GPS time has a TAI second rate and is monotonic. But of course you
would need a GPS receiver to access it.
I don't have a specific application in mind. Just a general question
on what should be used. But lets say i want to have a monotonic clock
for a computer system to timestamp events precisely and unambigously.
Yes, using GPS time (with or without going back to TAI) would be
a probable solution.
Are there any other time scales available that would fit that need?
Attila Kinali
Well, there is :
TT, Terrestrial Time, which is uniform (interval SI second), monotonic ;
with an epoc of
00h 00m 00s 1 Jan 1977 TAI with a constant offset such that [TT] = [TAI]
- 32.184s .
Or more exotic:
ET, Ephemeris Time, which is uniform and monotonic with a non SI second
of 1/31566925,9747 of the tropical year of 1900.
Julien Date is another , using SI second, but a numeric day label with
an epoc of initial epoc defined as (UT) at midday on Monday Jan 1 4713
BC in the Julian calendar. It is measured in days and fractions with
precision of about a millisecond and being numeric is so is easy to do
calculations on.
MJD , Modified Julien Date is the above -2400000,5 to keep the numbers
down. This was recognised as a time scale by the IUT. I think it is now
deprecated but is in common use.
There are probably others.
MJD , Modified Julien Date is the above -2400000,5 to keep the numbers
down. This was recognised as a time scale by the IUT. I think it is
now deprecated but is in common use.
There are probably others.
Oops, typo.. It should be UIT or ITU and not IUT and I forgot the cavet.
In general any exotic scale would have to be either created from scratch
or calculated from the available TAI based scales as none are
transmitted. Many web pages of course will give nice clock animations. I
recommend tvb's.
The clock animations at http://www.leapsecond.com/java/gpsclock.htm are
great, but one has to pay attention to the note at top, saying they are all
based on your PC's clock, not actual time. If your pc is off 5 seconds, so
will be all of those clocks.
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of mike cook
Sent: Thursday, August 11, 2011 1:02 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Why not TAI?
MJD , Modified Julien Date is the above -2400000,5 to keep the numbers
down. This was recognised as a time scale by the IUT. I think it is
now deprecated but is in common use.
There are probably others.
Oops, typo.. It should be UIT or ITU and not IUT and I forgot the cavet.
In general any exotic scale would have to be either created from scratch
or calculated from the available TAI based scales as none are
transmitted. Many web pages of course will give nice clock animations. I
recommend tvb's.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Le 11/08/2011 16:25, Jose Camara a écrit :
The clock animations at http://www.leapsecond.com/java/gpsclock.htm are
great, but one has to pay attention to the note at top, saying they are all
based on your PC's clock, not actual time. If your pc is off 5 seconds, so
will be all of those clocks.
Yes indeed. It was on looking at them yesterday that I discovered that
my PC clock was 7 sec adrift. I had not restarted ntp after maintenance
some weeks back and :(
Tony:
I followed your suggestion and got both "Seize the Daylight" and
"Spring Forward" from my local library.
Seize the daylight : the curious and contentious story of daylight
saving time / David Prerau / ISBN 1560256559
Spring forward : the annual madness of daylight saving / Michael
Downing / ISBN 1582434956
Both have very interesting facts about the history of DST, but IMO
"Seize the Daylight" is a much more enjoyable reading, following a script
that better describes the events around each change (and has illustrations,
too...). Things that some of us late 20th century creatures don't realize,
like major city times, that would be off 35 minutes and only became a
problem when trains started to connect them. Farmer's point of view,
crusades for DST, war, etc.
After reading them, I'm cured - no more posts defending, criticizing
or suggesting amendments to DST. I just belong to the a certain DST
'religion' that would prefer we didn't have a 1hr step change twice a year,
period. No desire to evangelize anyone in the other DST denominations, which
is Quixotean task just as futile. It is too late now.
Now if they propose changing the thermometer scales, to show 10
degrees higher in winter, 10 degrees lower in summer, to do similar mass
hypnosis to save heating and a/c energy, I'll write my congresswoman. :-)
Thanks for the book recommendation.
Jose
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Tony Finch
Sent: Monday, July 18, 2011 5:24 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] The future of UTC
Jose Camara camaraq1@quantacorp.com wrote:
I think before adding to the fire of UTC1, UTC7 etc. why not just abolish
this silliness called Daylight Savings Time? If there is any benefit to
it,
just change business operating hours instead.
If you want to know why your suggestion doesn't work, David Prerau has
collected many many examples. http://www.seizethedaylight.com/
Tony.
f.anthony.n.finch dot@dotat.at http://dotat.at/
Fair Isle: Northerly or northeasterly 4 or 5 increasing 5 or 6, but 6 or 7
in
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Jose Camara camaraq1@quantacorp.com wrote:
Thanks for the book recommendation.
I'm enormously pleased you enjoyed it. Sounds like you had the same
unexpected reaction that I did!
Tony.
f.anthony.n.finch dot@dotat.at http://dotat.at/
Northwest FitzRoy, Sole, Lundy, Fastnet: Westerly or southwesterly 4 or 5.
Moderate or rough. Occasional rain. Good, occasionally poor.