Re: [LEAPSECS] Risks of change to UTC

From: Brian Garrett <mgy1912_at_cox.net>
Date: Fri, 20 Jan 2006 22:53:34 -0800

----- Original Message -----
From: "James Maynard" <james.h.maynard_at_USA.NET>
To: <LEAPSECS_at_ROM.USNO.NAVY.MIL>
Sent: Friday, January 20, 2006 9:33 PM
Subject: Re: [LEAPSECS] Risks of change to UTC


> M. Warner Losh wrote:
> > In message: <43D1650B.1000301_at_usa.net>
> > James Maynard <james.h.maynard_at_USA.NET> writes:
> > : M. Warner Losh wrote:
> > : > In message: <43D15F4C.5_at_usa.net>
> > : > James Maynard <james.h.maynard_at_USA.NET> writes:
> > : > : ones position using sight reduction tables. Today a mechanical
watch or
> > : > : chronometer, or a battery-powered wristwatch, can be set to UTC
using
> > : > : radio time signals. Then when power fails, the sailor still has a
> > : > : reasonably accurate spprodximation to UT1 available.
> > : >
> > : > If DUT1 is broadcast, then one can set the time keeping device to
UT1
> > : > by a means similar to setting it to UTC, even if DUT1 exceeds 0.9s
> > : > with a similar accuacy (or better). There's nothing that says a
watch
> > : > has to display UTC to be set correctly.
> > : >
> > : > Warner
> > : >
> > : > .
> > : >
> > : And how is DUT1 to be broadcast in a language-independent manner?
That
> > : protocol needs to be established well in advance.
> >
> > It already is being broadcast in, eg, WWV.
> >
> > Warner
> >
> >
> >
> But the protocol for broadcasting DUT1 in, e.g., WWV, does not provide
> for DUT1 values of more than plus or minus 0.9 s. The value of DUT1
> could be announced by voice message -- but that would not be
> language-independent. If I travel to asia in my boat, I will not be
> able to benefit from DUT1 announcemnts in Japanese from JJY or in
> Chinese from BPM (or whatever their standard time and frequency station
> is). An longwave broadcasts such as those from WWVB do not have voice
> modulation at all!
>
WWVB broadcasts the DUT1 correction in binary-coded decimal form, and is
capable of representing DUT1 values up to +/- 1.5 seconds with their current
format. I would think other longwave stations do the same, but not knowing
their particular BCD format I couldn't say what DUT1 values they are capable
of representing.

Brian Garrett
Received on Fri Jan 20 2006 - 22:53:57 PST