Which pips?

On Tue, 10 Sep 2013 19:47:02 +0100, Another John
wrote:

OP here - thanks chaps: a very interesting and informative discussion!

Of course, I don't _really_ need to know which pips are the more
accurate, I was just curious (given that we were brought up to believe
that the Pips are THE exact time). If I do ever need to know the
precise time (and which of us ever does?) then I have my Aldi weather
station, which tunes into one of them there atomic clocks.

Cheers
J.

All timekeeping assumes the duration of a second is constant. The
second may be redefined soon.

See http://www.bbc.co.uk/news/science-environment-23231206

Steve

--
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In article ,
Phil Cook wrote:
On 10/09/2013 18:41, Scott wrote:
On Mon, 09 Sep 2013 17:10:28 -0500, "Steve Thackery"
wrote:



To summarise: the FM pips. The DAB pips are delayed because your DAB
radio takes a certain time to decode the signal.

I understood the 'official' pips were on long wave and that FM was
delayed albeit nothing like as much as DAB.

Surely the propagation delays on FM would be the same as AM?

But the distribution delays could be longer.

--
From KT24

Using a RISC OS computer running v5.18

"Another John" wrote in message
...
I'm sure this has been asked many times before, but I haven't seen it
....

I had both my digital radio and my FM radio on this teatime, in
different rooms. At 6pm The Pips were broadcast. Given that digital is
always out of synch with FM -- which is the more accurate time signal?


Come to think of it I have another question, related, and equally dumb.
Given that digital is digital, and therefore completely under the
control of the broadcasters (as opposed to the 'organic' FM signal), why
in the name of all that's holy do "they" not synchronise the football
commentary over digital radio, so that it matches TV coverage of the
game? It's bloody annoying hearing about a goal several seconds before
(or sometimes after?) it happens!

John

The FM radio pips are accurate - I have a radio controlled watch (from
Rugby) programmed to bleep twice on the hour. The two bleeps go around the
six pip for the hour.

In article ,
R. Mark Clayton wrote:
The FM radio pips are accurate - I have a radio controlled watch (from
Rugby) programmed to bleep twice on the hour. The two bleeps go around
the six pip for the hour.

But given the slow speed of sound, wouldn't that depend on how close your
ears are to the radio and watch?

--
*How does Moses make his tea? Hebrews it.*

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Dave Plowman (News) wrote:

But given the slow speed of sound, wouldn't that depend on how close your
ears are to the radio and watch?

Somewhat to my surprise, the threshold of simultaneity for sound events
has been measured at 2ms[1]. At 300m/s, that's only 60cm.

[1] See for example http://www.jaimeoliver.pe/courses/ci...vitin-1999.pdf,
which references "A History of Experimental Psychology" by E. Boring.

-- Richard

Richard Tobin wrote:
In article ,
Dave Plowman (News) wrote:

But given the slow speed of sound, wouldn't that depend on how close
your ears are to the radio and watch?

Somewhat to my surprise, the threshold of simultaneity for sound
events
has been measured at 2ms[1]. At 300m/s, that's only 60cm.

[1] See for example
http://www.jaimeoliver.pe/courses/ci...vitin-1999.pdf, which
references "A History of Experimental Psychology" by E. Boring.

I saw an experiment performed on TV, possibly on the Royal Society's
Christmas lectures a few years ago but I can't remember precisely, that
involved a hollow hula hoop which had been cut, and the two open ends
placed in a person's ears. The person was blindfolded and the
experimenter then tapped on the hoop, starting at the centre and moving
gradually towards one ear or the other. He asked the person to indicate
whether he was tapping on the right or left side. It was remarkable how
little distance he had to go off centre (only about 10cm if I recall)
before the person could accurately say which side. From the result he
could calculate the threshold of simultaneity.

So could I if I could be bothered, but suffice it to say it was tiny.

On Wed, 11 Sep 2013 15:17:09 +0100, "Norman Wells"
wrote:

I saw an experiment performed on TV, possibly on the Royal Society's
Christmas lectures a few years ago but I can't remember precisely, that

pedant mode on

Those would have been the Royal Institution Christmas lectures.

The Royal Institution is not the Royal Society.

pedant mode off

--
Peter Duncanson
(in uk.tech.digital-tv)

In article , Scott
scribeth thus
On Tue, 10 Sep 2013 19:11:58 +0100, Phil Cook
wrote:

On 10/09/2013 18:41, Scott wrote:
On Mon, 09 Sep 2013 17:10:28 -0500, "Steve Thackery"
wrote:



To summarise: the FM pips. The DAB pips are delayed because your DAB
radio takes a certain time to decode the signal.

I understood the 'official' pips were on long wave and that FM was
delayed albeit nothing like as much as DAB.

Surely the propagation delays on FM would be the same as AM?

I believe the delay is in distribution to the network of FM
transmitters.

Yep, these days I don't think anyone is using analogue lines anymore.

Some stations, community ones, might be using Band 1 (52 MHz) for an STL
link but thats about all...
--
Tony Sayer

In article , Ian Jackson ianREMOVET
scribeth thus
In message , Scott
writes
On Mon, 09 Sep 2013 17:10:28 -0500, "Steve Thackery"
wrote:



To summarise: the FM pips. The DAB pips are delayed because your DAB
radio takes a certain time to decode the signal.

I understood the 'official' pips were on long wave

That could well be so. Although there are two fill-in transmitters in
Scotland, Droitwich LW is directly receivable over all of the rest of
the UK, so reception times will be almost simultaneous. However, the
delays on the audio feeds to all the other transmitters (LW and FM) will
vary (especially if carried on telephone lines, and less so on fibre),

Umm .. manly on fibre nowadays for a lot of the length and a short bit
of copper, if at all. Fibre is run into studio and dist centres and some
TX sites....

Plus codecs and coders and decoders etc .. all adds up..



so depending on their path lengths, the delays would vary quite a bit (a
few milliseconds?).

and that FM was
delayed albeit nothing like as much as DAB.




--
Tony Sayer

In article , Dave Plowman (News)
scribeth thus
In article ,
Ian Jackson wrote:
However, the
delays on the audio feeds to all the other transmitters (LW and FM) will
vary (especially if carried on telephone lines, and less so on fibre),
so depending on their path lengths, the delays would vary quite a bit (a
few milliseconds?).

The distribution system is digital and will invariably introduce delay.
Maybe not much but easily measurable.

Droitwich at one time had a direct DC analogue line as a backup. Dunno if
it still has.


What all the way to BH?..
--
Tony Sayer