"Dave Plowman (News)" wrote

I was told the land line to Brookmans Park used for R2 (light prog) on
247? metres was originally installed for pre-war TV sound which was
'advertised' as being of better quality than radio. And had about double
the bandwidth of a normal circuit.
All that came from a BBC lines person in the '60s. FWIW. After I asked why
my Quad AM tuner sounded so much better on R2 than other AM stations.


Brookmans Park was used to transmit Baird 30-line TV from 1930 to 1935. And
that required about 13kHz to give equal vertical and horizontal definition.
It's possible that one of the lines to BP was specially upgraded for that
use.

The pre-war TV sound that was advertised as being of "better quality" (-3dB
at 10kHz) was that from the "high-definition" (405-line) station at
Alexandra Palace.

David.

In message , "Dave Plowman (News)"
writes
In article ,
David Looser wrote:
"Don Pearce" wrote

The GPO line that fed the main London medium wave Home Service
transmitter had a pretty dreadful rolloff, which the Beeb engineers
used to limit the frequency response offered to the transmitter. At
some point the line was changed to a better one and all of a sudden
the medium wave service was going out to about 12kHz. After a few
months this was noticed, and a lowpass filter was put in.

Can't remember the exact dates, I'm afraid, but it was while John Peel
had his Top Gear programme on Sunday afternoons.

Sounds like an urban legend to me. Do you have any evidence that this
extraordinary claim is true?

I was told the land line to Brookmans Park used for R2 (light prog) on
247? metres was originally installed for pre-war TV sound which was
'advertised' as being of better quality than radio. And had about double
the bandwidth of a normal circuit.
All that came from a BBC lines person in the '60s. FWIW. After I asked why
my Quad AM tuner sounded so much better on R2 than other AM stations.
There was also something else about the 247 wavelength which allowed the
BBC to broadcast a wider bandwidth than some of the other frequencies
allocated to them.

On lower frequencies, aerials have lower (absolute) bandwidth -
especially if they are loaded to resonate them. The same goes for tuned
circuits (in the transmitter, matching, diplexing etc). I might be
wrong, but I believe that the audio from the LW transmitter on 200 (now
198) kHz is affected (reduced) by the aerial RF bandwidth (as is the
audio phase response), and some pre-emphasis is needed. I'm not sure if
such effects are significant on the MW but, potentially, the 247m signal
(around 1.2MHz) could be wider than the 909kHz.
--
Ian

David Looser wrote:
"Andrew Haley" wrote in message
m...

Pure Oasis. Cracking piece of kit: showerproof, damn loud (important
in a shower)

I cannot for the life of me image why anyone needs a radio in a shower!

To listen to The Archers, of course! :-)

Nor can I see why anyone needs to use DAB for R3 or R4, esp if they
need to run it off batteries.

Interesting. I've always had terrible problems indoors with multipath
interference on FM: wherever I moved it'd make a horrible fizzing
sound. I would re-orientate the antenna, whereupon it'd make the
fizzing noise when I moved somewhere else. I've still got FM
portables, but I have no intention of using them as long as the DAB
keeps working.

Andrew.

tony sayer wrote:
In article , Andrew
Haley scribeth thus
Gordon MacPherson wrote:

Looking for a DAB radio to leave in the bathroom! Main problem is
reception - it seems to be a weak signal - so sensitivity is an
issue. Also must run on batteries so battery life is a
consideration. Does not need any fancy features - radios 3 and 4!

Pure Oasis. Cracking piece of kit: showerproof, damn loud (important
in a shower) and decent battery life. There's a new version, the
Oasis Flow, that has analogue radio too. I find the reception
execellent, but I'm in Cambridge which has middling DAB signal
strength.

Well Cambridge has according to Arqiva and the BBC excellent strength a
mix of Band 3 mitters from Madingley up to 5 kW !..

Aha, that explains why the reception is so good these days. My info
was well out of date. I stand corrected, thanks.

Andrew.

In article niN7o.36344$Pi3.12119@hurricane, Woody
wrote:
"Dave Plowman (News)" wrote in message
...
In article , David Looser
wrote:

The Light Programme was 1500m (200KHz) LW. Radio 1 started on 247m
(1217KHz) and the Home Service (R4) was on 330m (911KHz) and 433m
(695KHz). I seem to remember the Third Programme (R3) was on 495m
(603KHz) or something like that. Note these frequencies are those used
before the UK came into line with the rest of the 9KHz world and
'corrected' the frequencies to be integer multiples.

WRT to comments re the John Peel prog and that era, I'm trying to recall
when Radio 1 progs started being duplicated on Radio 2 for a time at the
weekends so as to get some 'pop' onto FM.

My memory may be playing tricks on me here. But I still have a recording of
Joni Mitchell 'In Concert' on Radio 1 from 1969 which I think was from FM.
IIRC correctly it was preceeded by John Drummond and John Peel. Must listen
to the recording again. :-)

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

In article , Don Pearce
wrote:
On Sun, 08 Aug 2010 16:54:22 +0100, Jim Lesurf
wrote:

Assuming peaks on R3 are '0dB' seems a little excessive to me. Being
the BBC I'd expect them to allow headroom. But fair enough for just
looking at spectra bandwidths/shapes.


No, the Radio 3 peaks are nowhere near 0dB. I left the gain where it was
after I maxed it on Radio2.

Sorry. Finger trouble. My brain (sic) intended to type "R2". But I guess my
fingers decided I must mean "R3" as I listen to that more of the time. :-)

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

In article niN7o.36344$Pi3.12119@hurricane,
Woody wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
David Looser wrote:
"Don Pearce" wrote

The GPO line that fed the main London medium wave Home
Service
transmitter had a pretty dreadful rolloff, which the Beeb
engineers
used to limit the frequency response offered to the
transmitter. At
some point the line was changed to a better one and all of a
sudden
the medium wave service was going out to about 12kHz. After
a few
months this was noticed, and a lowpass filter was put in.

Can't remember the exact dates, I'm afraid, but it was while
John Peel
had his Top Gear programme on Sunday afternoons.

Sounds like an urban legend to me. Do you have any evidence
that this
extraordinary claim is true?

I was told the land line to Brookmans Park used for R2 (light
prog) on
247? metres was originally installed for pre-war TV sound which
was
'advertised' as being of better quality than radio. And had
about double
the bandwidth of a normal circuit.
All that came from a BBC lines person in the '60s. FWIW. After
I asked why
my Quad AM tuner sounded so much better on R2 than other AM
stations.
There was also something else about the 247 wavelength which
allowed the
BBC to broadcast a wider bandwidth than some of the other
frequencies
allocated to them.

--


The Light Programme was 1500m (200KHz) LW. Radio 1 started on 247m
(1217KHz) and the Home Service (R4) was on 330m (911KHz) and 433m
(695KHz). I seem to remember the Third Programme (R3) was on 495m
(603KHz) or something like that. Note these frequencies are those used
before the UK came into line with the rest of the 9KHz world and
'corrected' the frequencies to be integer multiples.

It certainly wasn't long wave I was referring to. Could well have been R1
on medium wave - which carried some R2 progs at various times.

The line would have been to Droitwich (there was no MW London repeater
in those days - that came much later) and I would guess they might have
been able to get away with a wider bandwidth due to lack of proximity
of adjacent stations.

No - definitely BP. That bit I'm sure of.

Interestingly, a few years ago (OK, maybe the 80's) Atlantic 252
transmitted from the RoI used a form of vestigial sideband which gave a
subjectively 'cleaner' sound. I think in fact it was a lower sideband
and the actual carrier frewuency was 254KHz but I could be wrong.

--
*I used up all my sick days so I called in dead

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

In article ,
David Looser wrote:
"Dave Plowman (News)" wrote

I was told the land line to Brookmans Park used for R2 (light prog) on
247? metres was originally installed for pre-war TV sound which was
'advertised' as being of better quality than radio. And had about
double the bandwidth of a normal circuit. All that came from a BBC
lines person in the '60s. FWIW. After I asked why my Quad AM tuner
sounded so much better on R2 than other AM stations.


Brookmans Park was used to transmit Baird 30-line TV from 1930 to 1935.
And that required about 13kHz to give equal vertical and horizontal
definition. It's possible that one of the lines to BP was specially
upgraded for that use.

The pre-war TV sound that was advertised as being of "better quality"
(-3dB at 10kHz) was that from the "high-definition" (405-line) station
at Alexandra Palace.

It's quite possible the BP circuit was routed through AP.

--
*Many hamsters only blink one eye at a time *

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

"Dave Plowman (News)" wrote in message
...
In article ,
David Looser wrote:
"Dave Plowman (News)" wrote

I was told the land line to Brookmans Park used for R2 (light prog) on
247? metres was originally installed for pre-war TV sound which was
'advertised' as being of better quality than radio. And had about
double the bandwidth of a normal circuit. All that came from a BBC
lines person in the '60s. FWIW. After I asked why my Quad AM tuner
sounded so much better on R2 than other AM stations.


Brookmans Park was used to transmit Baird 30-line TV from 1930 to 1935.
And that required about 13kHz to give equal vertical and horizontal
definition. It's possible that one of the lines to BP was specially
upgraded for that use.

The pre-war TV sound that was advertised as being of "better quality"
(-3dB at 10kHz) was that from the "high-definition" (405-line) station
at Alexandra Palace.

It's quite possible the BP circuit was routed through AP.


Nope. BP came into service in 1930; whilst AP wasn't even chosen to be the
site for the "high-definition" service until 1935. I've never heard any
suggestion that cables to BP were re-routed to go via AP after 1935 and
there would have been absolutely no point in doing so. BP was a MW radio
transmitter whilst TV was broadcast only from AP. BP did not, could not,
broadcast TV sound. The pre-war TV service from AP was very largely
independant of BBC radio, but if they did need to link up with the world of
BBC sound radio they had direct lines to BH.

David.

In article ,
David Looser wrote:
It's quite possible the BP circuit was routed through AP.


Nope. BP came into service in 1930; whilst AP wasn't even chosen to be
the site for the "high-definition" service until 1935. I've never
heard any suggestion that cables to BP were re-routed to go via AP
after 1935 and there would have been absolutely no point in doing so.
BP was a MW radio transmitter whilst TV was broadcast only from AP. BP
did not, could not, broadcast TV sound. The pre-war TV service from AP
was very largely independant of BBC radio, but if they did need to link
up with the world of BBC sound radio they had direct lines to BH.

Should have put a question mark after my comment.

Lines were always a bit of a mystery to me - handled by someone on the end
of a phone. Can't ask my pal about it either - he's no longer with us.

--
He who laughs last, thinks slowest*

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