time delays on dab vs analogue
 

"Ray Pearce" wrote in message
...
"Max Demian" wrote in message
...
because they haven't "been sent from Herstmonseaux" for at least 20
years.
The 'pips' come from a generator in BH. I'm sure it could be adjusted
to
be a few seconds early - or even 14 minutes and 53 seconds late.

If that's true, perhaps you should update Wikipedia:
http://en.wikipedia.org/wiki/Greenwich_Time_Signal


Umm, that page says:
The pips for national radio stations and some local radio stations are
timed relative to UTC, from an atomic clock in the basement of
Broadcasting House

Did someone already update it?

No, I missed the bit in the Accuracy section. I would have expected it to be
in the History section as well, saying when the current arrangement started.

--
Max Demian

time delays on dab vs analogue
 

In article ,
says...

I have a Braun alarm clock

http://cgi.ebay.co.UK/BRAUN-LUBS-DB-12-fsl-ALARM-CLOCK--DIETER-RAMS-ERA_W0QQitemZ140351519969QQcmdZViewItemQQimsxq2009 1018?IMSfp=TL091018139001r10699

which displays a circle outline on its LCD when it is trying to synchronize,
and this only appears about 7 seconds before the hour ...

.... so, presumably, reads data transmitted during the first minute of
each hour. Does it remember the presence/absence of the Summertime
announcement from the previous hour and act on it correctly? (I assume
that it receives DCF77 rather than MSF.)

It would make more sense to receive minute 59 so that it could also
correctly respond to the leap second marker.

From memory, AFAIK there is no advance warning of summertime on MSF so
an MSF clock would *have* to read data during minute 59 (which is, of
course, the data relating to the following minute 00, to respond
correctly).

--

Terry

time delays on dab vs analogue
 

In article ,
says...

"Terry Casey" wrote

I think most of these master clocks were based Hipp, rather than
Synchronome, movements. (Invented by Mathias Hipp around 1830.)


I guess that the constant amplitude feature must have compensated for the
extra complication involved in the toggle mechanism.


Someone has published comparative graphs to demonstrate the difference

http://www.bmumford.com/mset/symposium/page19.html

--

Terry

time delays on dab vs analogue
 

On Wed, 21 Oct 2009 17:42:21 +0100, Terry Casey wrote:

In article ,
says...

I have a Braun alarm clock

http://cgi.ebay.co.UK/BRAUN-LUBS-DB-12-fsl-ALARM-CLOCK--DIETER-RAMS-ERA_W0QQitemZ140351519969QQcmdZViewItemQQimsxq2009 1018?IMSfp=TL091018139001r10699

which displays a circle outline on its LCD when it is trying to
synchronize, and this only appears about 7 seconds before the hour ...

... so, presumably, reads data transmitted during the first minute of
each hour.

Apologies -- my memory was in error and what I thought was happening is
not the case. Careful observation reveals that the synchronization
process (for this hour anyways) began at :58:33 in plenty of time for
any adjustment needed around the end of the 59th minute.

Does it remember the presence/absence of the Summertime
announcement from the previous hour and act on it correctly?

When I check the time on it after the night that the hour springs forwards/
falls back, it does show the correct time. ;)

In fact I seem to recall observing the change correctly occuring at the
specified hour when I was up late once, with the display jumping from
01:59h to 03:00h.

(I assume that it receives DCF77 rather than MSF.)

Yes it receives DFC77 only. There are but a very few clocks which have
a DCF77/MSF switch.

It would make more sense to receive minute 59 so that it could also
correctly respond to the leap second marker.

You are correct and that is undoubtedly what is in fact happening.

Details of the contents of the DCF77 time signal (with diagram) can
be found at

http://www.captain.AT/howto-dcf77-time-code.php

Concerning summertime changes

QUOTE

The announcement bit A1 (No. 16) indicates an imminent change-over of
the time system. Before the transition from CET to CEST or back takes
place, A1 is emitted for one hour in state one: before change-over
from CET to CEST (CEST to CET) from 01:00:16 h CET (02:00:16 h CEST)
until 01:59:16 h CET (02:59:16 h CEST).

UNQUOTE

And for leap seconds

QUOTE

Announcement bit A2 (No. 19) adverts the imminent introduction of a
leap second. A2 is also emitted for one hour in state one before a
leap second is inserted. Before a leap second is inserted on the 1st
of January (1st of July), A2 is therefore emitted sixty times from
00:00:19 h CET (01:00:19 h CEST) until 00:59:19 h CET (01:59:19 h CEST)
in state one.

UNQUOTE

time delays on dab vs analogue
 

In article ,
says...

On Wed, 21 Oct 2009 17:42:21 +0100, Terry Casey wrote:

In article ,
says...

I have a Braun alarm clock

http://cgi.ebay.co.UK/BRAUN-LUBS-DB-12-fsl-ALARM-CLOCK--DIETER-RAMS-ERA_W0QQitemZ140351519969QQcmdZViewItemQQimsxq2009 1018?IMSfp=TL091018139001r10699


The e-bay entry says that it cannot be adjusted to display UTC and is,
therefore, always an hour fast! Is this correct?

And, if so, does that mean that you are also content with a very
innaccurate/accurate clock or that you reside outside of the British
Isles and Portugal but within the DCF77 transmission area?

Details of the contents of the DCF77 time signal (with diagram) can
be found at

http://www.captain.AT/howto-dcf77-time-code.php


The 'clock dial' diagram is a very useful way of displaying how the code
is distributed throughout each minute. I used to have one for MSF in a
Mullard (so it must be a very old!) application note which I no longer
have ...

The closest I can find to it is he

http://www.c-maxgroup.com/tech/msf.php

which, unfortunately omits the coding for the first 16 seconds of each
minute, which is rather a pity, as I think it is this bit that really
differentiates the MSF & DCF77 transmissions (rather than transmission
differences).

As explained here (but not as clearly):

http://en.wikipedia.org/wiki/Time_from_NPL#Protocol

these bits are used to show the difference between our very accurate
atomic digital time and astronomical time, which is the 'real time' of
our analogue world - and of considerable importance to astronomers.

It is this difference, if it exceeds 700mS, which triggers a leap
second, if required, at the end of each six month period. Should the
difference be negative, we would lose a second (a leap-back second?)
but that hasn't happened - yet!


--

Terry

time delays on dab vs analogue
 

On Wed, 21 Oct 2009 22:38:54 +0100, Terry Casey wrote:

The e-bay entry says that it cannot be adjusted to display UTC and is,
therefore, always an hour fast! Is this correct?

Yes, it cannot be adjusted to UTC, and is therefore either UTC+1 or UTC+2.

And, if so, does that mean that you are also content with a very
innaccurate/accurate clock or that you reside outside of the British
Isles and Portugal but within the DCF77 transmission area?

Yes to both questions ;)

It is this difference, if it exceeds 700mS, which triggers a leap
second, if required, at the end of each six month period. Should the
difference be negative, we would lose a second (a leap-back second?)
but that hasn't happened - yet!

Well according to

http://tycho.usno.navy.MIL/leapsec.html

QUOTE

The Earth is constantly undergoing a deceleration caused by the braking
action of the tides.

UNQUOTE

Thus it would appear that it is unlikely a backwards leap second will
be required under normal operating conditions.

time delays on dab vs analogue
 

In article en.co.uk,
Roderick Stewart wrote:
In article , Mark Carver wrote:
Remind me again, what does the 'I' in NICAM stand for ?


but the N stands for "Near"

Yes, well, Near enough :-)

I did conduct an experiment once when Holme Moss became receivable in
Hampshire during a lift. I tuned one radio to Rowridge, the other to
Holme Moss. I could not hear any time delay.

I suspect that most of the delays associated with digital processing
actually result from the extreme bit-rate reduction that many of them
now use, rather than the process of converting the signal from analogue
to digital in the first place.

Perhaps also from the data then being spread across symbol time slots to
help distribute bit losses from Ignition Interference.

Although what interests me about this is the evident differences in delays
between different models, etc, of RX even when dealing with the same
signal. Has anyone compared the outputs to see how similar they are in
other ways?

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

time delays on dab vs analogue
 

On Wed, 21 Oct 2009 22:38:54 +0100, Terry Casey wrote:

The 'clock dial' diagram is a very useful way of displaying how the code
is distributed throughout each minute. I used to have one for MSF in a
Mullard (so it must be a very old!) application note which I no longer
have ...

The closest I can find to it is he

http://www.c-maxgroup.com/tech/msf.php

which, unfortunately omits the coding for the first 16 seconds of each
minute, which is rather a pity, as I think it is this bit that really
differentiates the MSF & DCF77 transmissions (rather than transmission
differences).

Description of DUT-1 data is he
http://www.npl.co.uk/upload/pdf/MSF_Time_Date_Code.pdf

The link to it on the site you quoted is outdated.

time delays on dab vs analogue
 

On Wed, 21 Oct 2009 00:31:34 +0000 (UTC), J G Miller
wrote:

On Tue, 20 Oct 2009 23:31:30 +0100, Mark Carver wrote:

Depends how far away you are from Droitwich

Does that also affect the thousands of people listening in these areas?

Aberdeen ...... 1449 kHz
Bromley ........ 720 kHz
Carlisle ...... 1495 kHz
Derry .......... 720 kHz
Enniskillen .... 774 kHz
Glasgow ........ 720 kHz
Plymouth ....... 774 kHz
Redruth ........ 756 kHz
Tyneside ....... 603 kHz

Radio 4 UK, not just on LF, but MF too.

Are your sure about this? I don't see any mention of Aberdeen being
1449 kHz. Surely they will receive the long wave signal from
Burghead? Likewise are you sure about Bromley? I don't see any
mention of it. Carlisle is 1485 not 1495. I am sure there is no
local 720 kHz transmitter in Glasgow as the signal is very weak. ( I
assume it comes from Northern Ireland.)

time delays on dab vs analogue
 

"Scott" wrote in message
...
On Wed, 21 Oct 2009 00:31:34 +0000 (UTC), J G Miller
wrote:

On Tue, 20 Oct 2009 23:31:30 +0100, Mark Carver wrote:

snip
Likewise are you sure about Bromley? I don't see any
mention of it. Carlisle is 1485 not 1495. I am sure there is no
local 720 kHz transmitter in Glasgow as the signal is very weak. ( I
assume it comes from Northern Ireland.)


http://en.wikipedia.org/wiki/Crystal...itting_station

Steve Terry