----- Original Message ----- From: "James Maynard" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Friday, January 20, 2006 9:33 PM Subject: Re: [LEAPSECS] Risks of change to UTC
> M. Warner Losh wrote: > > In message: <[EMAIL PROTECTED]> > > James Maynard <[EMAIL PROTECTED]> writes: > > : M. Warner Losh wrote: > > : > In message: <[EMAIL PROTECTED]> > > : > James Maynard <[EMAIL PROTECTED]> 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
