On Fri, 25 May 2007 18:25:27 +0100, Steve Pardoe wrote:

I'm sure that's right for a lot of users, but surely a landline from
Teddington will be more reliable than MSF?

But you can't get a straight bit of copper from BT now only digital stuff
in one form or another with all the built in and variable latency etc. Not
to mention the cost, not only for installation but rental as well.

Indeed it is, but again I wonder how many bodies now use it ; and of
course a constant sinewave is much easier to lock to than
once-per-second modulation.

If one is interested in seriously accurate time you don't lock your clock
to an external source you just compare your tuned and accurate clock with
the standards over fairly long periods of time (hours to days). Think
about it, MSF is maintained to better than 2 x 10^-12 (2 millionths of a
millionth of 1s) your own clock will have similar accuracy. How long will
it take for any drift between the two to become measurable? These aren't
things you switch on then seconds later you have accurate time, they take
a long time to stabilse and then synchoronise. The on/off nature of the
60kHz MSF carrier is barely relevant.

While we're on the off-topic of time, it strikes me as perverse that the
BBC (and perhaps others) persist in broadcasting the pips on digital TV,
even though they are a couple of seconds late

Because they are part of the real analogue network and all these other new
fangled services are just hanging on the back of that. There was some
talk about running BH a set amount ahead of clock time and applying
various delays in the various feeds but when you really start looking at
the implications it rapidly becomes impractical.

--
Cheers
Dave. pam is missing e-mail