"Clive D.W. Feather" wrote on 2005-08-05 07:48 UTC:
> At the other end of the scale, BBC radio transmits the "Greenwich Time
> Signal" on many channels on many hours, so the public expects it to be
> correct.
Oh, those good old analog broadcast days are soon gone.
With the move to MPEG audio compression on many radio and TV broadcast
channels, both the transmission latency and its variance have risen to
several seconds. Unfortunately, the standards committees defining the
DAB and DVB digital audio and video broadcasting standards neglected to
define the exact phase offsets to be maintained between the transmitter
and the receiver clock. As a result, the BBC beeps can be several
seconds off these days and it is not easily possible for the broadcaster
to compensate for the transmission delay. I'd expect them to sooner or
later give up and remove sub-minute accuracy clock displays (such as the
famous beeps) from these broadcasts.
Markus
--
Markus Kuhn, Computer Laboratory, University of Cambridge
http://www.cl.cam.ac.uk/~mgk25/ || CB3 0FD, Great Britain
Received on Fri Aug 05 2005 - 04:56:16 PDT