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The BBC, PCM and NICAM for radio
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Jim Lesurf
Nov 24, 2011, 12:13:56 PM11/24/11
to
Hi,
I've just put up a new page that people may find an interesting read, It
outlines the history of the use of PCM and NICAM by the BBC to distribute
their radio networks. You can find the page at
http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
My thanks to the many excellent ex-BBC engineers who have helped and
advised.
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/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html
I've just put up a new page that people may find an interesting read, It
outlines the history of the use of PCM and NICAM by the BBC to distribute
their radio networks. You can find the page at
http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
My thanks to the many excellent ex-BBC engineers who have helped and
advised.
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/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html
charles
Nov 24, 2011, 12:29:06 PM11/24/11
to
In article <5237419...@audiomisc.co.uk>,
worry about.
--
From KT24
Using a RISC OS computer running v5.16
Jim Lesurf <no...@audiomisc.co.uk> wrote:
> Hi,
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
an excellent document. I've possibly got the odd quibble, but nothing to
> Hi,
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
worry about.
--
From KT24
Using a RISC OS computer running v5.16
Dave Plowman (News)
Nov 24, 2011, 1:18:47 PM11/24/11
to
> Hi,
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
Excellent article, Jim. Just as I (no longer) remember it. ;-)
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
Would you check the end of the second paragraph from the top?
--
*I'll try being nicer if you'll try being smarter
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
Jim Lesurf
Nov 24, 2011, 1:18:01 PM11/24/11
to
In article <523742f8...@charleshope.demon.co.uk>, charles
During the production process (a better description that saying I 'wrote'
it) I decided that the best I could hope for was to get a sort of 'least
squares fit minimum value' from all the comments from about a dozen
engineers who had various quibbles. :-)
I do plan that various subtopics will be dealt with in future by other
pages that go into more depth and expose some of the details that I had to
gloss over and simplify to get such a short description and have it
readable by non-engineers. The detailed pages will also let those involved
give more direct comments and their POV, etc.
I regard the page I've done as a sort of potted overview that reminds
people of a number of historic/significant/fascinating events, etc. But
also as a central point around which more could be built.
For now, though, I'm going on to 'something completely different' for a
while and let my head clear of things like EDI and equipment code numbers,
and details of the bits! There is still a lot to find out.
it) I decided that the best I could hope for was to get a sort of 'least
squares fit minimum value' from all the comments from about a dozen
engineers who had various quibbles. :-)
I do plan that various subtopics will be dealt with in future by other
pages that go into more depth and expose some of the details that I had to
gloss over and simplify to get such a short description and have it
readable by non-engineers. The detailed pages will also let those involved
give more direct comments and their POV, etc.
I regard the page I've done as a sort of potted overview that reminds
people of a number of historic/significant/fascinating events, etc. But
also as a central point around which more could be built.
For now, though, I'm going on to 'something completely different' for a
while and let my head clear of things like EDI and equipment code numbers,
and details of the bits! There is still a lot to find out.
Mark Carver
Nov 24, 2011, 5:31:37 PM11/24/11
to
On 24/11/2011 17:13, Jim Lesurf wrote:
> Hi,
>
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
>
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
>
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
Nice stuff Jim, copied to uk.tech.broadcast
> Hi,
>
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
>
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
>
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
--
Mark
Please replace invalid and invalid with gmx and net to reply.
www.paras.org.uk
Don Pearce
Nov 24, 2011, 5:57:31 PM11/24/11
to
On Thu, 24 Nov 2011 22:31:37 +0000, Mark Carver
<mark....@invalid.invalid> wrote:
>On 24/11/2011 17:13, Jim Lesurf wrote:
>> Hi,
>>
>> I've just put up a new page that people may find an interesting read, It
>> outlines the history of the use of PCM and NICAM by the BBC to distribute
>> their radio networks. You can find the page at
>>
>> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
>>
>> My thanks to the many excellent ex-BBC engineers who have helped and
>> advised.
>
>Nice stuff Jim, copied to uk.tech.broadcast
You look like you could answer this:
<mark....@invalid.invalid> wrote:
>On 24/11/2011 17:13, Jim Lesurf wrote:
>> Hi,
>>
>> I've just put up a new page that people may find an interesting read, It
>> outlines the history of the use of PCM and NICAM by the BBC to distribute
>> their radio networks. You can find the page at
>>
>> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
>>
>> My thanks to the many excellent ex-BBC engineers who have helped and
>> advised.
>
>Nice stuff Jim, copied to uk.tech.broadcast
In a communal antenna system what optimum signal level would you
target for digital terrestrial TV? And is there an industry standard
for minimum acceptable level?
d
David Looser
Nov 24, 2011, 6:12:13 PM11/24/11
to
"Jim Lesurf" <no...@audiomisc.co.uk> wrote in message
news:5237419...@audiomisc.co.uk...
the poor quality of long-distance analogue music circuits. But it's worth
pointing out that the GPO was trying to phase out analogue music circuits at
that time because they were a nuisance to the GPO which was then in the
process of converting its junction and trunk network from baseband audio and
FDM to PCM. So the parallel conversion of BBC circuits to PCM dovetailed in
nicely with what the GPO/BT was doing. Of course telephone PCM was of rather
lower quality than the BBC's. It used an 8kHz sampling rate and non-linear
quantisation steps (known as A-law) to give 12-bit resolution for low levels
signals but increasingly lower resolution at higher signal levels; overall
bit rate being 64kb/s. 30 such circuits (plus 2 signalling channels, giving
an overall bit rate of 2048kb/s) formed the basic level multiplex and were
used to replace baseband audio on twisted-pair junction circuits giving a
15-fold increase in traffic capacity for a much lower cost than having to
install additional line-plant. Several of these basic-level multiplexes
would then be multiplexed together to form higher level multiplexes
replacing FDM on long-distance trunk co-ax cable routes. My understanding is
that the BBC designed their equipment so that their digital bit-streams
could directly replace that from an integral number of 2048kb/s telephone
systems on such trunk circuits.
David.
news:5237419...@audiomisc.co.uk...
> Hi,
>
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
>
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
>
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
>
Interesting stuff. You mentioned that much of the reason for using PCM was
>
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
>
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
>
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
>
the poor quality of long-distance analogue music circuits. But it's worth
pointing out that the GPO was trying to phase out analogue music circuits at
that time because they were a nuisance to the GPO which was then in the
process of converting its junction and trunk network from baseband audio and
FDM to PCM. So the parallel conversion of BBC circuits to PCM dovetailed in
nicely with what the GPO/BT was doing. Of course telephone PCM was of rather
lower quality than the BBC's. It used an 8kHz sampling rate and non-linear
quantisation steps (known as A-law) to give 12-bit resolution for low levels
signals but increasingly lower resolution at higher signal levels; overall
bit rate being 64kb/s. 30 such circuits (plus 2 signalling channels, giving
an overall bit rate of 2048kb/s) formed the basic level multiplex and were
used to replace baseband audio on twisted-pair junction circuits giving a
15-fold increase in traffic capacity for a much lower cost than having to
install additional line-plant. Several of these basic-level multiplexes
would then be multiplexed together to form higher level multiplexes
replacing FDM on long-distance trunk co-ax cable routes. My understanding is
that the BBC designed their equipment so that their digital bit-streams
could directly replace that from an integral number of 2048kb/s telephone
systems on such trunk circuits.
David.
dave
Nov 24, 2011, 6:51:20 PM11/24/11
to
On 24/11/2011 23:12, David Looser wrote:
>> advised.
>>
> Interesting stuff. You mentioned that much of the reason for using PCM was
> the poor quality of long-distance analogue music circuits. But it's worth
> pointing out that the GPO was trying to phase out analogue music circuits at
> that time because they were a nuisance to the GPO which was then in the
> process of converting its junction and trunk network from baseband audio and
> FDM to PCM. So the parallel conversion of BBC circuits to PCM dovetailed in
> nicely with what the GPO/BT was doing. Of course telephone PCM was of rather
> lower quality than the BBC's. It used an 8kHz sampling rate and non-linear
> quantisation steps (known as A-law) to give 12-bit resolution for low levels
> signals but increasingly lower resolution at higher signal levels; overall
> bit rate being 64kb/s. 30 such circuits (plus 2 signalling channels, giving
> an overall bit rate of 2048kb/s) formed the basic level multiplex and were
> used to replace baseband audio on twisted-pair junction circuits giving a
> 15-fold increase in traffic capacity for a much lower cost than having to
> install additional line-plant. Several of these basic-level multiplexes
> would then be multiplexed together to form higher level multiplexes
> replacing FDM on long-distance trunk co-ax cable routes. My understanding is
> that the BBC designed their equipment so that their digital bit-streams
> could directly replace that from an integral number of 2048kb/s telephone
> systems on such trunk circuits.
>
Dave's been cutting and pasting from google searches again.
>> advised.
>>
> Interesting stuff. You mentioned that much of the reason for using PCM was
> the poor quality of long-distance analogue music circuits. But it's worth
> pointing out that the GPO was trying to phase out analogue music circuits at
> that time because they were a nuisance to the GPO which was then in the
> process of converting its junction and trunk network from baseband audio and
> FDM to PCM. So the parallel conversion of BBC circuits to PCM dovetailed in
> nicely with what the GPO/BT was doing. Of course telephone PCM was of rather
> lower quality than the BBC's. It used an 8kHz sampling rate and non-linear
> quantisation steps (known as A-law) to give 12-bit resolution for low levels
> signals but increasingly lower resolution at higher signal levels; overall
> bit rate being 64kb/s. 30 such circuits (plus 2 signalling channels, giving
> an overall bit rate of 2048kb/s) formed the basic level multiplex and were
> used to replace baseband audio on twisted-pair junction circuits giving a
> 15-fold increase in traffic capacity for a much lower cost than having to
> install additional line-plant. Several of these basic-level multiplexes
> would then be multiplexed together to form higher level multiplexes
> replacing FDM on long-distance trunk co-ax cable routes. My understanding is
> that the BBC designed their equipment so that their digital bit-streams
> could directly replace that from an integral number of 2048kb/s telephone
> systems on such trunk circuits.
>
--
UnsteadyKen
Nov 24, 2011, 8:32:28 PM11/24/11
to
Jim Lesurf wrote...
> It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
>
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
>
I like your writing style, engaging and authoritative but not overly
formal .
--
Ken O'Meara
http://www.btinternet.com/~unsteadyken/
David Looser
Nov 25, 2011, 2:09:23 AM11/25/11
to
"dave" <da...@hytre.net> wrote in message
news:166dnVuwhcnlRVPT...@brightview.co.uk...
David.
news:166dnVuwhcnlRVPT...@brightview.co.uk...
> On 24/11/2011 23:12, David Looser wrote:
>
>>> advised.
>>>
>>
>
>>> advised.
>>>
>>
> Dave's been cutting and pasting from google searches again.
> --
Who's "Dave"? you?
> --
David.
Jim Lesurf
Nov 25, 2011, 3:40:09 AM11/25/11
to
In article <5237478...@davenoise.co.uk>, Dave Plowman (News)
*to* what we"
OK. I've also had a number of other tweaks suggested, so I'll make some of
the later today when I get a chance.
I've been having a dozen people 'proof' drafts for a couple of weeks
looking for quibbles and typos. But Sod's Law ensures some will end up in
the published result! :-)
<da...@davenoise.co.uk> wrote:
> In article <5237419...@audiomisc.co.uk>, Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
> > Hi,
> > I've just put up a new page that people may find an interesting read,
> > It outlines the history of the use of PCM and NICAM by the BBC to
> > distribute their radio networks. You can find the page at
> > http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
> > My thanks to the many excellent ex-BBC engineers who have helped and
> > advised.
> Excellent article, Jim. Just as I (no longer) remember it. ;-)
> Would you check the end of the second paragraph from the top?
Ah. You mean it should read more like "sound quality was quite inferior
> In article <5237419...@audiomisc.co.uk>, Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
> > Hi,
> > I've just put up a new page that people may find an interesting read,
> > It outlines the history of the use of PCM and NICAM by the BBC to
> > distribute their radio networks. You can find the page at
> > http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
> > My thanks to the many excellent ex-BBC engineers who have helped and
> > advised.
> Excellent article, Jim. Just as I (no longer) remember it. ;-)
> Would you check the end of the second paragraph from the top?
*to* what we"
OK. I've also had a number of other tweaks suggested, so I'll make some of
the later today when I get a chance.
I've been having a dozen people 'proof' drafts for a couple of weeks
looking for quibbles and typos. But Sod's Law ensures some will end up in
the published result! :-)
Jim Lesurf
Nov 25, 2011, 3:48:07 AM11/25/11
to
In article <9j81ad...@mid.individual.net>, David Looser
> Interesting stuff. You mentioned that much of the reason for using PCM
> was the poor quality of long-distance analogue music circuits. But it's
> worth pointing out that...
Yes. There is a lot more to that, and to various other issues. I'm still
slowly collecting details and trying to resolve apparent disagreements.
Also getting my sorted out in my head a lot of the details which were quite
surprising - and sometimes confusing at first!
> Of course telephone PCM was of rather lower quality than the BBC's. It
> used an 8kHz sampling rate and non-linear quantisation steps (known as
> A-law) to give 12-bit resolution for low levels signals but increasingly
> lower resolution at higher signal levels; overall bit rate being 64kb/s.
Yes, the BBC people did consider this. But in the end decided the 'all
digital' NICAM made more sense for them.
One detail I've not yet covered is the remarkable design of the original
13-bit ADCs for PCM. They used a method I'd not encountered before.
> My understanding is that the BBC designed their equipment so that their
> digital bit-streams could directly replace that from an integral number
> of 2048kb/s telephone systems on such trunk circuits.
The initial PCM was based on a mux of about 6Megs/sec, but various 8M
system started to come in, so they changed to make use of that for the
'hybrid' and full-NICAM. However there were many 'special cases' all over
the shop over the years. So sorting out and explaining this in detail is
hard. As is the actual various channel waveform methods, etc.
I did actually have go at explaining NRZ codings at one point. But removed
that and was happy to use Graham Sawdy's photos of Sandale kit. Thought
that was more in keeping with the rest of the article and an excellent
thing to include.
So for now, I've just avoided the complex bits. :-)
<david....@btinternet.com> wrote:
> "Jim Lesurf" <no...@audiomisc.co.uk> wrote in message
> news:5237419...@audiomisc.co.uk...
> >
> > http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
> "Jim Lesurf" <no...@audiomisc.co.uk> wrote in message
> news:5237419...@audiomisc.co.uk...
> >
> Interesting stuff. You mentioned that much of the reason for using PCM
> was the poor quality of long-distance analogue music circuits. But it's
Yes. There is a lot more to that, and to various other issues. I'm still
slowly collecting details and trying to resolve apparent disagreements.
Also getting my sorted out in my head a lot of the details which were quite
surprising - and sometimes confusing at first!
> Of course telephone PCM was of rather lower quality than the BBC's. It
> used an 8kHz sampling rate and non-linear quantisation steps (known as
> A-law) to give 12-bit resolution for low levels signals but increasingly
> lower resolution at higher signal levels; overall bit rate being 64kb/s.
digital' NICAM made more sense for them.
One detail I've not yet covered is the remarkable design of the original
13-bit ADCs for PCM. They used a method I'd not encountered before.
> My understanding is that the BBC designed their equipment so that their
> digital bit-streams could directly replace that from an integral number
> of 2048kb/s telephone systems on such trunk circuits.
system started to come in, so they changed to make use of that for the
'hybrid' and full-NICAM. However there were many 'special cases' all over
the shop over the years. So sorting out and explaining this in detail is
hard. As is the actual various channel waveform methods, etc.
I did actually have go at explaining NRZ codings at one point. But removed
that and was happy to use Graham Sawdy's photos of Sandale kit. Thought
that was more in keeping with the rest of the article and an excellent
thing to include.
So for now, I've just avoided the complex bits. :-)
Jim Lesurf
Nov 25, 2011, 3:53:45 AM11/25/11
to
In article <MPG.293900804...@news.btinternet.com>,
UnsteadyKen
The difficulty is to steer between it being readable by those who are
innocent of (BBC) engineering, and being acceptable to those who know far
more and can see all the simplifications and bits that are glossed over.
The main intent was twofold.
To raise the profile of the work involved. I think we owe those involved a
lot of thanks for producing such an excellent radio network via pioneering
engineering.
To make clear just how much BBC FM has for decades depended on 'hidden
digits'. Even more remarkably, just 14/10 bits/sample, yet still well
regarded in the age of CD and 96/24 'high rez'.
My real regret is that the BBC itself seems to take little interest in its
own engineering history and achievement - particularly in radio.
UnsteadyKen
<unste...@gmail.com> wrote:
> Jim Lesurf wrote...
> > It outlines the history of the use of PCM and NICAM by the BBC to
> > distribute their radio networks. You can find the page at
> >
> > http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
> >
> An excellent and illuminating article Jim. I like your writing style,
> engaging and authoritative but not overly formal .
I'm tempted to say, "Don't clap! Throw money!" :-)
> Jim Lesurf wrote...
> > It outlines the history of the use of PCM and NICAM by the BBC to
> > distribute their radio networks. You can find the page at
> >
> > http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
> >
> An excellent and illuminating article Jim. I like your writing style,
> engaging and authoritative but not overly formal .
The difficulty is to steer between it being readable by those who are
innocent of (BBC) engineering, and being acceptable to those who know far
more and can see all the simplifications and bits that are glossed over.
The main intent was twofold.
To raise the profile of the work involved. I think we owe those involved a
lot of thanks for producing such an excellent radio network via pioneering
engineering.
To make clear just how much BBC FM has for decades depended on 'hidden
digits'. Even more remarkably, just 14/10 bits/sample, yet still well
regarded in the age of CD and 96/24 'high rez'.
My real regret is that the BBC itself seems to take little interest in its
own engineering history and achievement - particularly in radio.
Dave Plowman (News)
Nov 25, 2011, 5:33:23 AM11/25/11
to
In article <5237966...@audiomisc.co.uk>,
> OK. I've also had a number of other tweaks suggested, so I'll make some
> of the later today when I get a chance.
> I've been having a dozen people 'proof' drafts for a couple of weeks
> looking for quibbles and typos. But Sod's Law ensures some will end up in
> the published result! :-)
Of course. I've often found the most stupid mistakes in something I've
written long afterwards - despite having checked it many times. Hence I
think the reasons for a proof reader - who doesn't need to understand the
subject, just look for obvious things.
--
*I thought I wanted a career. Turns out I just wanted paychecks.
Jim Lesurf <no...@audiomisc.co.uk> wrote:
> > Would you check the end of the second paragraph from the top?
> Ah. You mean it should read more like "sound quality was quite inferior
> *to* what we"
Yup.
> > Would you check the end of the second paragraph from the top?
> Ah. You mean it should read more like "sound quality was quite inferior
> *to* what we"
> OK. I've also had a number of other tweaks suggested, so I'll make some
> of the later today when I get a chance.
> I've been having a dozen people 'proof' drafts for a couple of weeks
> looking for quibbles and typos. But Sod's Law ensures some will end up in
> the published result! :-)
written long afterwards - despite having checked it many times. Hence I
think the reasons for a proof reader - who doesn't need to understand the
subject, just look for obvious things.
--
*I thought I wanted a career. Turns out I just wanted paychecks.
Dave Plowman (News)
Nov 25, 2011, 5:38:44 AM11/25/11
to
In article <523797a...@audiomisc.co.uk>,
reverse, it seems. Just what they can get away with.
It's perhaps more understandable in a commercial operation where the only
motivation is profit, but not with the BBC.
--
*Real men don't waste their hormones growing hair
Jim Lesurf <no...@audiomisc.co.uk> wrote:
> My real regret is that the BBC itself seems to take little interest in
> its own engineering history and achievement - particularly in radio.
Engineering excellence simply isn't of interest to the suits. Quite the
> My real regret is that the BBC itself seems to take little interest in
> its own engineering history and achievement - particularly in radio.
reverse, it seems. Just what they can get away with.
It's perhaps more understandable in a commercial operation where the only
motivation is profit, but not with the BBC.
--
*Real men don't waste their hormones growing hair
tony sayer
Nov 25, 2011, 7:11:11 AM11/25/11
to
In article <4ececb63...@news.eternal-september.org>, Don Pearce
<sp...@spam.com> scribeth thus
I would imagine Bill Wright, Mr TV aerial for Yorkshire would be best
placed to answer this .. are you around Bill?.....
--
Tony Sayer
<sp...@spam.com> scribeth thus
placed to answer this .. are you around Bill?.....
--
Tony Sayer
Bill Wright
Nov 25, 2011, 7:53:56 AM11/25/11
to
tony sayer wrote:
>> In a communal antenna system what optimum signal level would you
>> target for digital terrestrial TV? And is there an industry standard
>> for minimum acceptable level?
>
>> In a communal antenna system what optimum signal level would you
>> target for digital terrestrial TV? And is there an industry standard
>> for minimum acceptable level?
>
> I would imagine Bill Wright, Mr TV aerial for Yorkshire would be best
> placed to answer this .. are you around Bill?.....
Yes, I'm around.
> placed to answer this .. are you around Bill?.....
Leaving aside the 'official' figures, which you can look up, the answer
isn't all that straightforward.
The reason is that to state a minimum figure at the wallplate is really
just an expression of the expected noise figure of the receiver, plus
the necessary s/n ratio, plus a bit for luck. Receivers vary widely, as
do receiver environments (RF from other items) and the quality of the
screening of the feeder and the wallplate.
The other main complication is that the s/n ratio of the signals carried
on the feeder will not be infinite, so there is a variable noise
contribution there.
However, if you present a good receiver with a signal that is
accompanied by negligible noise (straight from an aerial that is
receiving a strong signal with no CCI or other interference) and make
sure the feeder is well screened so there's no pick up of local RF, it's
surprising what you can get away with. I have a twenty quid Currys
Essentials box on my bench that is working on 26dBuV. There are
occasional glitches. The box has a duckfit if I turn the light on.
However, that's under perfect circumstances, and the real world, and as
all of us older than a day know to our cost, the real world isn't perfect.
So, although 40dBuV will generally work, I don't like to leave outlets
with less that 50dBuV.
As for an upper limit, well, 65 or 70 is reasonable. There are never
problems at that level.
Bill
Ian Jackson
Nov 25, 2011, 8:26:10 AM11/25/11
to
In message <jao35b$5f0$1...@speranza.aioe.org>, Bill Wright
<bi...@invalid.com> writes
I haven't checked, but I'm pretty sure that the analogue level spec on
large multi-channel cable TV systems was 63 to 75dBuV at the wall socket
(and less than 3dB between adjacent channels). However, these high
levels were based on the fact that the set-top boxes had relatively poor
noise figures (typically 7 to 10dB). TV sets themselves are (and were)
much lower. Also, the minimum analogue carrier-to-noise spec at the
outlet was 46dB - which is a lot worse then you might expect to get from
a relatively small MATV system (which might consist of maybe just a
low-noise preamp cascaded with one more distribution amplifier on any
one leg of the system).
--
Ian
<bi...@invalid.com> writes
large multi-channel cable TV systems was 63 to 75dBuV at the wall socket
(and less than 3dB between adjacent channels). However, these high
levels were based on the fact that the set-top boxes had relatively poor
noise figures (typically 7 to 10dB). TV sets themselves are (and were)
much lower. Also, the minimum analogue carrier-to-noise spec at the
outlet was 46dB - which is a lot worse then you might expect to get from
a relatively small MATV system (which might consist of maybe just a
low-noise preamp cascaded with one more distribution amplifier on any
one leg of the system).
--
Ian
Don Pearce
Nov 25, 2011, 8:28:00 AM11/25/11
to
On Fri, 25 Nov 2011 12:53:56 +0000, Bill Wright <bi...@invalid.com>
wrote:
The reason I ask is that a friend's house has just had CATV installed
in place of an external antenna I fitted years ago. The difference I
notice is that on her new Sony TV's HD channels, my antenna signal is
comfortably in the green for strength, and 100% for quality, whereas
the CATV signal is just hovering at the top of the red for both. I
suspect the noise figure of the CATV signal is good because a decent
size Yagi has line of sight to Crystal Palace about 10 miles away. But
I think the system is new enough that she can reasonably ask for the
wick to be turned up a bit. I haven't measured her signal levels, but
what you say here gives me some idea of what they should be aiming
for.
d
wrote:
in place of an external antenna I fitted years ago. The difference I
notice is that on her new Sony TV's HD channels, my antenna signal is
comfortably in the green for strength, and 100% for quality, whereas
the CATV signal is just hovering at the top of the red for both. I
suspect the noise figure of the CATV signal is good because a decent
size Yagi has line of sight to Crystal Palace about 10 miles away. But
I think the system is new enough that she can reasonably ask for the
wick to be turned up a bit. I haven't measured her signal levels, but
what you say here gives me some idea of what they should be aiming
for.
d
Jim Lesurf
Nov 25, 2011, 9:18:30 AM11/25/11
to
In article <5237a0c...@davenoise.co.uk>, Dave Plowman (News)
engineers'. :-)
<da...@davenoise.co.uk> wrote:
> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
> > > Would you check the end of the second paragraph from the top?
> > Ah. You mean it should read more like "sound quality was quite
> > inferior *to* what we"
> Yup.
Now fixed that and some other typos and late corrections from 'the
> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
> > > Would you check the end of the second paragraph from the top?
> > Ah. You mean it should read more like "sound quality was quite
> > inferior *to* what we"
> Yup.
engineers'. :-)
Don Pearce
Nov 25, 2011, 9:48:33 AM11/25/11
to
On Fri, 25 Nov 2011 14:18:30 +0000 (GMT), Jim Lesurf
<no...@audiomisc.co.uk> wrote:
>In article <5237a0c...@davenoise.co.uk>, Dave Plowman (News)
><da...@davenoise.co.uk> wrote:
>> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
>> <no...@audiomisc.co.uk> wrote:
>> > > Would you check the end of the second paragraph from the top?
>
>> > Ah. You mean it should read more like "sound quality was quite
>> > inferior *to* what we"
>
>> Yup.
>
>Now fixed that and some other typos and late corrections from 'the
>engineers'. :-)
>
>Slainte,
>
>Jim
Still doesn't look right - missing the "what". Or isn't it uploaded
<no...@audiomisc.co.uk> wrote:
>In article <5237a0c...@davenoise.co.uk>, Dave Plowman (News)
><da...@davenoise.co.uk> wrote:
>> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
>> <no...@audiomisc.co.uk> wrote:
>> > > Would you check the end of the second paragraph from the top?
>
>> > Ah. You mean it should read more like "sound quality was quite
>> > inferior *to* what we"
>
>> Yup.
>
>Now fixed that and some other typos and late corrections from 'the
>engineers'. :-)
>
>Slainte,
>
>Jim
yet?
d
J G Miller
Nov 25, 2011, 10:56:01 AM11/25/11
to
On Friday, November 25th, 2011, at 12:53:56h +0000, Bill Wright wrote:
> I have a twenty quid Currys Essentials box on my bench that is
> working on 26dBuV. There are occasional glitches. The box has a
> duckfit if I turn the light on.
Sorry if this seems like an impertinent and irrelevant question,
> I have a twenty quid Currys Essentials box on my bench that is
> working on 26dBuV. There are occasional glitches. The box has a
> duckfit if I turn the light on.
but does it matter if the light is incandescent, fluorescent,
CFL, or LED?
Or is it the switch its-self?
Mark Carver
Nov 25, 2011, 11:23:36 AM11/25/11
to
On 25/11/2011 08:53, Jim Lesurf wrote:
> The main intent was twofold.
>
> To raise the profile of the work involved. I think we owe those involved a
> lot of thanks for producing such an excellent radio network via pioneering
> engineering.
I wonder how other European national broadcasters, (some with
> The main intent was twofold.
>
> To raise the profile of the work involved. I think we owe those involved a
> lot of thanks for producing such an excellent radio network via pioneering
> engineering.
geographical spreads that dwarf ours) dealt with the challenge in the
1970s ?
Jim Lesurf
Nov 25, 2011, 10:18:58 AM11/25/11
to
In article <4ecfaa64...@news.eternal-september.org>, Don Pearce
of argument between me and 'higher management' (my wife) over the
alternative "that which" phrasing, but I prefer "what".
<sp...@spam.com> wrote:
> On Fri, 25 Nov 2011 14:18:30 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
> >In article <5237a0c...@davenoise.co.uk>, Dave Plowman (News)
> ><da...@davenoise.co.uk> wrote:
> >> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
> >> <no...@audiomisc.co.uk> wrote:
> >> > > Would you check the end of the second paragraph from the top?
> >
> >> > Ah. You mean it should read more like "sound quality was quite
> >> > inferior *to* what we"
> >
> >> Yup.
> >
> >Now fixed that and some other typos and late corrections from 'the
> >engineers'. :-)
> On Fri, 25 Nov 2011 14:18:30 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
> >In article <5237a0c...@davenoise.co.uk>, Dave Plowman (News)
> ><da...@davenoise.co.uk> wrote:
> >> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
> >> <no...@audiomisc.co.uk> wrote:
> >> > > Would you check the end of the second paragraph from the top?
> >
> >> > Ah. You mean it should read more like "sound quality was quite
> >> > inferior *to* what we"
> >
> >> Yup.
> >
> >Now fixed that and some other typos and late corrections from 'the
> >engineers'. :-)
> Still doesn't look right - missing the "what". Or isn't it uploaded yet?
Boooger. I'll fix that. Your pointing this out also prompted a flurry
of argument between me and 'higher management' (my wife) over the
alternative "that which" phrasing, but I prefer "what".
Steve Thackery
Nov 25, 2011, 11:51:29 AM11/25/11
to
Jim Lesurf wrote:
> The initial PCM was based on a mux of about 6Megs/sec
Would that have been based on the American PCM hierarchy? They used 24
> The initial PCM was based on a mux of about 6Megs/sec
channel, 1536kb/s PCM links, rather than the 32 channel, 2048kb/s
systems used in Europe.
It was common to bind four together to produce 6M/8M pipes.
I did wonder if the initial kit was brought in from the US.
--
SteveT
Steve Thackery
Nov 25, 2011, 11:52:54 AM11/25/11
to
Jim Lesurf wrote:
> the
> alternative "that which" phrasing, but I prefer "what".
You uncouth heathen! :-)
> the
> alternative "that which" phrasing, but I prefer "what".
--
SteveT
Jim Lesurf
Nov 25, 2011, 11:55:01 AM11/25/11
to
In article <9j9to8...@mid.individual.net>, Mark Carver
seems very much a system that had to be invented and devised at the BBC to
get the required performance. Indeed, the more details I learned about that
system, the more impressed I became by the ingenuity of the BBC engineers.
We take so much for granted these days that wasn't available then.
Later on, I understand that NICAM was used abroad. But what I've seen on
that mainly talks about TV, not radio distribution. Although I wonder if
some countries may have 'solved' such problems by simply having regional
broadcasting, thus avoiding the need to send good stereo audio over long
distance distribution! :-)
<mark....@invalid.invalid> wrote:
> On 25/11/2011 08:53, Jim Lesurf wrote:
> > The main intent was twofold.
> >
> > To raise the profile of the work involved. I think we owe those
> > involved a lot of thanks for producing such an excellent radio network
> > via pioneering engineering.
> I wonder how other European national broadcasters, (some with
> geographical spreads that dwarf ours) dealt with the challenge in the
> 1970s ?
I'm also curious about that, but have no idea of the answer(s). The BBC PCM
> On 25/11/2011 08:53, Jim Lesurf wrote:
> > The main intent was twofold.
> >
> > To raise the profile of the work involved. I think we owe those
> > involved a lot of thanks for producing such an excellent radio network
> > via pioneering engineering.
> I wonder how other European national broadcasters, (some with
> geographical spreads that dwarf ours) dealt with the challenge in the
> 1970s ?
seems very much a system that had to be invented and devised at the BBC to
get the required performance. Indeed, the more details I learned about that
system, the more impressed I became by the ingenuity of the BBC engineers.
We take so much for granted these days that wasn't available then.
Later on, I understand that NICAM was used abroad. But what I've seen on
that mainly talks about TV, not radio distribution. Although I wonder if
some countries may have 'solved' such problems by simply having regional
broadcasting, thus avoiding the need to send good stereo audio over long
distance distribution! :-)
Don Pearce
Nov 25, 2011, 12:18:27 PM11/25/11
to
On Fri, 25 Nov 2011 15:18:58 +0000 (GMT), Jim Lesurf
for the fluent read every time.
d
<no...@audiomisc.co.uk> wrote:
>In article <4ecfaa64...@news.eternal-september.org>, Don Pearce
><sp...@spam.com> wrote:
>> On Fri, 25 Nov 2011 14:18:30 +0000 (GMT), Jim Lesurf
>> <no...@audiomisc.co.uk> wrote:
>
>> >In article <5237a0c...@davenoise.co.uk>, Dave Plowman (News)
>> ><da...@davenoise.co.uk> wrote:
>> >> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
>> >> <no...@audiomisc.co.uk> wrote:
>> >> > > Would you check the end of the second paragraph from the top?
>> >
>> >> > Ah. You mean it should read more like "sound quality was quite
>> >> > inferior *to* what we"
>> >
>> >> Yup.
>> >
>> >Now fixed that and some other typos and late corrections from 'the
>> >engineers'. :-)
>
>
>> Still doesn't look right - missing the "what". Or isn't it uploaded yet?
>
>Boooger. I'll fix that. Your pointing this out also prompted a flurry
>of argument between me and 'higher management' (my wife) over the
>alternative "that which" phrasing, but I prefer "what".
>
>Jim
Maybe technically correct, but "that which" is awfully clumsy. I'd go
>In article <4ecfaa64...@news.eternal-september.org>, Don Pearce
><sp...@spam.com> wrote:
>> On Fri, 25 Nov 2011 14:18:30 +0000 (GMT), Jim Lesurf
>> <no...@audiomisc.co.uk> wrote:
>
>> >In article <5237a0c...@davenoise.co.uk>, Dave Plowman (News)
>> ><da...@davenoise.co.uk> wrote:
>> >> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
>> >> <no...@audiomisc.co.uk> wrote:
>> >> > > Would you check the end of the second paragraph from the top?
>> >
>> >> > Ah. You mean it should read more like "sound quality was quite
>> >> > inferior *to* what we"
>> >
>> >> Yup.
>> >
>> >Now fixed that and some other typos and late corrections from 'the
>> >engineers'. :-)
>
>
>> Still doesn't look right - missing the "what". Or isn't it uploaded yet?
>
>Boooger. I'll fix that. Your pointing this out also prompted a flurry
>of argument between me and 'higher management' (my wife) over the
>alternative "that which" phrasing, but I prefer "what".
>
>Jim
for the fluent read every time.
d
Mark Carver
Nov 25, 2011, 12:20:35 PM11/25/11
to
On 25/11/2011 16:55, Jim Lesurf wrote:
>> I wonder how other European national broadcasters, (some with
>> geographical spreads that dwarf ours) dealt with the challenge in the
>> 1970s ?
>
> I'm also curious about that, but have no idea of the answer(s). The BBC PCM
> seems very much a system that had to be invented and devised at the BBC to
> get the required performance. Indeed, the more details I learned about that
> system, the more impressed I became by the ingenuity of the BBC engineers.
> We take so much for granted these days that wasn't available then.
>
> Later on, I understand that NICAM was used abroad. But what I've seen on
> that mainly talks about TV, not radio distribution. Although I wonder if
> some countries may have 'solved' such problems by simply having regional
> broadcasting, thus avoiding the need to send good stereo audio over long
> distance distribution! :-)
I often visit foreign national broadcasters, I must start asking them
>> I wonder how other European national broadcasters, (some with
>> geographical spreads that dwarf ours) dealt with the challenge in the
>> 1970s ?
>
> I'm also curious about that, but have no idea of the answer(s). The BBC PCM
> seems very much a system that had to be invented and devised at the BBC to
> get the required performance. Indeed, the more details I learned about that
> system, the more impressed I became by the ingenuity of the BBC engineers.
> We take so much for granted these days that wasn't available then.
>
> Later on, I understand that NICAM was used abroad. But what I've seen on
> that mainly talks about TV, not radio distribution. Although I wonder if
> some countries may have 'solved' such problems by simply having regional
> broadcasting, thus avoiding the need to send good stereo audio over long
> distance distribution! :-)
these questions ! The Nordic broadcasters do maintain high technical
standards for radio and TV, been eroded in recent years, just as ours
have, but I suspect similar, and probably, to an extent, proprietary
solutions were applied by them too in the 70s.
Bill Wright
Nov 25, 2011, 12:37:28 PM11/25/11
to
Ian Jackson wrote:
> I haven't checked, but I'm pretty sure that the analogue level spec on
> large multi-channel cable TV systems was 63 to 75dBuV at the wall socket
> (and less than 3dB between adjacent channels).
Yes that's right, but analogue needed a s/n ratio roughly 20dB better
> I haven't checked, but I'm pretty sure that the analogue level spec on
> large multi-channel cable TV systems was 63 to 75dBuV at the wall socket
> (and less than 3dB between adjacent channels).
than DTT, so in crude terms the delivered levels needed to be 20dB higher.
The old BBC advice was 1mV for BIV and 1.5mV for BV.
> However, these high
> levels were based on the fact that the set-top boxes had relatively poor
> noise figures (typically 7 to 10dB). TV sets themselves are (and were)
> much lower.
>Also, the minimum analogue carrier-to-noise spec at the
> outlet was 46dB - which is a lot worse then you might expect to get from
> a relatively small MATV system (which might consist of maybe just a
> low-noise preamp cascaded with one more distribution amplifier on any
> one leg of the system).
45dB of amplification end-to-end the system noise would be almost
negligible if the signal levels were correct, and assuming the levels at
the outlets were reasonable.
Bill
Bill Wright
Nov 25, 2011, 12:44:53 PM11/25/11
to
Don Pearce wrote:
> The reason I ask is that a friend's house has just had CATV installed
> in place of an external antenna I fitted years ago. The difference I
> notice is that on her new Sony TV's HD channels, my antenna signal is
> comfortably in the green for strength, and 100% for quality, whereas
> the CATV signal is just hovering at the top of the red for both.
You need to attenuate the signals by 6dB temporarily. If that affects
> The reason I ask is that a friend's house has just had CATV installed
> in place of an external antenna I fitted years ago. The difference I
> notice is that on her new Sony TV's HD channels, my antenna signal is
> comfortably in the green for strength, and 100% for quality, whereas
> the CATV signal is just hovering at the top of the red for both.
reception (I don't mean readings I mean reception) the levels are FAR
too low. Even a 10dB atten should have no effect.
> I
> suspect the noise figure of the CATV signal is good because a decent
> size Yagi has line of sight to Crystal Palace about 10 miles away.
aerial is OK. It only needs the levels to drop too far before
re-amplification, and after that you're amplifying a dirty old mess.
But
> I think the system is new enough that she can reasonably ask for the
> wick to be turned up a bit. I haven't measured her signal levels, but
> what you say here gives me some idea of what they should be aiming
> for.
reading but will only help the 'quality' reading if the poor quality is
caused by a poor signal to receiver noise ratio, as opposed to a poor
signal to system noise ratio.
That assumes that that the adjustment in the streetbox is be after any
amplification.
Bill
charles
Nov 25, 2011, 12:46:59 PM11/25/11
to
In article <jaojou$mik$1...@speranza.aioe.org>, Bill Wright <bi...@invalid.com>
wrote:
became less sensitive with newer models.
--
From KT24
Using a RISC OS computer running v5.16
wrote:
> Ian Jackson wrote:
> > I haven't checked, but I'm pretty sure that the analogue level spec on
> > large multi-channel cable TV systems was 63 to 75dBuV at the wall
> > socket (and less than 3dB between adjacent channels).
> Yes that's right, but analogue needed a s/n ratio roughly 20dB better
> than DTT, so in crude terms the delivered levels needed to be 20dB higher.
> The old BBC advice was 1mV for BIV and 1.5mV for BV.
which was arrived at after testing a number of sets. Interestingly, tuner
> > I haven't checked, but I'm pretty sure that the analogue level spec on
> > large multi-channel cable TV systems was 63 to 75dBuV at the wall
> > socket (and less than 3dB between adjacent channels).
> Yes that's right, but analogue needed a s/n ratio roughly 20dB better
> than DTT, so in crude terms the delivered levels needed to be 20dB higher.
> The old BBC advice was 1mV for BIV and 1.5mV for BV.
became less sensitive with newer models.
--
From KT24
Using a RISC OS computer running v5.16
Don Pearce
Nov 25, 2011, 12:57:24 PM11/25/11
to
On Fri, 25 Nov 2011 17:44:53 +0000, Bill Wright <bi...@invalid.com>
wrote:
Thanks, yes I understand all this (I'm currently working for Global
Invacom designing their Ka band transceiver for rural broadband) - it
is just the street-level implementation details I was hazy on. I
suspect the installation is good - it is certainly very tidily done,
and the longest cable run is about 50 yards.
Your point with the attenuator is well made, and I didn't think of
trying that. I can bring home a switched one and see how many dBs I
can dial in before the errors start appearing.
d
wrote:
Invacom designing their Ka band transceiver for rural broadband) - it
is just the street-level implementation details I was hazy on. I
suspect the installation is good - it is certainly very tidily done,
and the longest cable run is about 50 yards.
Your point with the attenuator is well made, and I didn't think of
trying that. I can bring home a switched one and see how many dBs I
can dial in before the errors start appearing.
d
Graham.
Nov 25, 2011, 1:14:33 PM11/25/11
to
and it mattered not whether it was LED, GLS, CFL, gas or oil.
This isn't a joke, I'll see if you can solve the puzzle though.
--
Graham.
%Profound_observation%
J G Miller
Nov 25, 2011, 1:42:47 PM11/25/11
to
On Friday, November 25th, 2011 at 18:14:33h +0000, Graham. wrote:
> I had a VHS tape that would stop playing if a light was turned on
A particular VHS cassette, or do you mean a particular VHS cassette player?
> I had a VHS tape that would stop playing if a light was turned on
Something to do with the infra red control on the machine?
Mark Carver
Nov 25, 2011, 1:49:42 PM11/25/11
to
leaking into the machine, and triggering the tape transport to stop ?
Dave Plowman (News)
Nov 25, 2011, 1:59:34 PM11/25/11
to
In article <jaolu2$qsn$1...@profound-observation.eternal-september.org>,
--
*My dog can lick anyone
Graham. <m...@privacy.net> wrote:
> I had a VHS tape that would stop playing if a light was turned on,
> and it mattered not whether it was LED, GLS, CFL, gas or oil.
> This isn't a joke, I'll see if you can solve the puzzle though.
Optical tape present sensor.
> I had a VHS tape that would stop playing if a light was turned on,
> and it mattered not whether it was LED, GLS, CFL, gas or oil.
> This isn't a joke, I'll see if you can solve the puzzle though.
--
*My dog can lick anyone
phil
Nov 25, 2011, 2:42:30 PM11/25/11
to
On 24/11/2011 17:13, Jim Lesurf wrote:
> Hi,
>
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
>
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
>
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
>
> Slainte,
> Hi,
>
> I've just put up a new page that people may find an interesting read, It
> outlines the history of the use of PCM and NICAM by the BBC to distribute
> their radio networks. You can find the page at
>
> http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
>
> My thanks to the many excellent ex-BBC engineers who have helped and
> advised.
>
>
> Jim
>
Brings back memories. My first job when starting at Kingswood was
making and testing the pcb for, I think, the synchronising frame
generator for the prototype PCM equipment. It used a mix of ttl and
MECL logic chips, which caused problems, as ttl was +5v and mecl was -5.2v.
Phil
tony sayer
Nov 25, 2011, 4:21:14 PM11/25/11
to
In article <4ed1d5eb...@news.eternal-september.org>, Don Pearce
<sp...@spam.com> scribeth thus
Rural at that sort of frequency?..
What sort of ranges do they expect before the trees and other clutter
screw it up?..
--
Tony Sayer
<sp...@spam.com> scribeth thus
What sort of ranges do they expect before the trees and other clutter
screw it up?..
--
Tony Sayer
David Looser
Nov 25, 2011, 4:53:19 PM11/25/11
to
"tony sayer" <to...@bancom.co.uk> wrote in message
news:gc47JRIK...@bancom.co.uk...
the "pole-line route". This was going to work at around 40GHz, the idea
being that repeaters would be mounted on the top of motorway lighting poles.
But once the implication of rain attenuation calculations came to be
appreciated the project was quietly dropped.
David.
news:gc47JRIK...@bancom.co.uk...
>>
>>Thanks, yes I understand all this (I'm currently working for Global
>>Invacom designing their Ka band transceiver for rural broadband)
>
> Rural at that sort of frequency?..
>
> What sort of ranges do they expect before the trees and other clutter
> screw it up?..
Several decades ago I was briefly part of a group working on what was called
>>Thanks, yes I understand all this (I'm currently working for Global
>>Invacom designing their Ka band transceiver for rural broadband)
>
> Rural at that sort of frequency?..
>
> What sort of ranges do they expect before the trees and other clutter
> screw it up?..
the "pole-line route". This was going to work at around 40GHz, the idea
being that repeaters would be mounted on the top of motorway lighting poles.
But once the implication of rain attenuation calculations came to be
appreciated the project was quietly dropped.
David.
SpamTrapSeeSig
Nov 25, 2011, 5:18:14 PM11/25/11
to
In article <jaolu2$qsn$1...@profound-observation.eternal-september.org>,
Graham. <m...@privacy.net> writes
Did it have a transparent plastic case, by any chance?
19 questions left...
--
SimonM
Graham. <m...@privacy.net> writes
19 questions left...
--
SimonM
Phil Allison
Nov 25, 2011, 7:27:25 PM11/25/11
to
"Mark Carver"
>
> I wonder how other European national broadcasters, (some with geographical
> spreads that dwarf ours) dealt with the challenge in the 1970s ?
** Here in Australia, the ABC ( government financed) operated a national FM
> I wonder how other European national broadcasters, (some with geographical
> spreads that dwarf ours) dealt with the challenge in the 1970s ?
network from about 1974 onwards.
Programs originated in Adelaide and were sent thousands of miles to the
other capitols via dozens of microwave links. The multiplexed L&R signal was
used to modulate the many carriers involved.
On occasion ( ie with a live concert at the Sydney Opera House) the signal
was broadcast direct in Sydney, where I live. The improvement in sound
quality was large and very obvious.
The ABC claimed this analogue FM network was done to "international
standards" which may be true but was still appalling.
One broadcaster here in Sydney ( a not for profit music society 2MBS FM) has
a studio space large enough to accommodate a small group of musicians. The
signal from this studio was sent a few miles via a match pair of rented
lines to the transmitter on the top of a tall building in the centre of
Sydney.
Live, Saturday afternoon broadcasts from them had the same sound quality (
in 1977 ) that we get from the best CDs now.
BTW I was listening with Quad ESL57s.
... Phil
Bill Wright
Nov 25, 2011, 8:10:47 PM11/25/11
to
charles wrote:
> In article <jaojou$mik$1...@speranza.aioe.org>, Bill Wright <bi...@invalid.com>
> wrote:
>> Ian Jackson wrote:
>
>>> I haven't checked, but I'm pretty sure that the analogue level spec on
>>> large multi-channel cable TV systems was 63 to 75dBuV at the wall
>>> socket (and less than 3dB between adjacent channels).
>> Yes that's right, but analogue needed a s/n ratio roughly 20dB better
>> than DTT, so in crude terms the delivered levels needed to be 20dB higher.
>
>> The old BBC advice was 1mV for BIV and 1.5mV for BV.
>
> which was arrived at after testing a number of sets.
Phew! Glad I remembered it right! Forgot you were here Charles!
> In article <jaojou$mik$1...@speranza.aioe.org>, Bill Wright <bi...@invalid.com>
> wrote:
>> Ian Jackson wrote:
>
>>> I haven't checked, but I'm pretty sure that the analogue level spec on
>>> large multi-channel cable TV systems was 63 to 75dBuV at the wall
>>> socket (and less than 3dB between adjacent channels).
>> Yes that's right, but analogue needed a s/n ratio roughly 20dB better
>> than DTT, so in crude terms the delivered levels needed to be 20dB higher.
>
>> The old BBC advice was 1mV for BIV and 1.5mV for BV.
>
> which was arrived at after testing a number of sets.
>Interestingly, tuner
> became less sensitive with newer models.
amp if the aerial signals were below 66dBuV.
Bill
Bill Wright
Nov 25, 2011, 8:12:17 PM11/25/11
to
Don Pearce wrote:
> Your point with the attenuator is well made, and I didn't think of
> trying that. I can bring home a switched one and see how many dBs I
> can dial in before the errors start appearing.
Use a 75ohm one!
> Your point with the attenuator is well made, and I didn't think of
> trying that. I can bring home a switched one and see how many dBs I
> can dial in before the errors start appearing.
Bill
Don Pearce
Nov 26, 2011, 2:51:56 AM11/26/11
to
On Fri, 25 Nov 2011 21:21:14 +0000, tony sayer <to...@bancom.co.uk>
wrote:
Should have mentioned - satellite-based.
d
wrote:
d
Don Pearce
Nov 26, 2011, 2:52:52 AM11/26/11
to
On Sat, 26 Nov 2011 01:12:17 +0000, Bill Wright <bi...@invalid.com>
wrote:
I have plenty of low loss 75 to 50 ohm matches.
d
wrote:
d
Ian Jackson
Nov 26, 2011, 3:11:48 AM11/26/11
to
In message <japeb1$tqf$1...@speranza.aioe.org>, Bill Wright
<bi...@invalid.com> writes
Engineering Building, in Hayes, Middlesex, the lab Sony 1310UB used to
get 19 nineteen channels without an aerial (and I think that was before
we had Channel 4).
--
Ian
<bi...@invalid.com> writes
>charles wrote:
>> In article <jaojou$mik$1...@speranza.aioe.org>, Bill Wright <bi...@invalid.com>
>> wrote:
>>> Ian Jackson wrote:
>>
>>>> I haven't checked, but I'm pretty sure that the analogue level spec
>>>>
>> In article <jaojou$mik$1...@speranza.aioe.org>, Bill Wright <bi...@invalid.com>
>> wrote:
>>> Ian Jackson wrote:
>>
>>>> I haven't checked, but I'm pretty sure that the analogue level spec
>>>>
>>>> large multi-channel cable TV systems was 63 to 75dBuV at the wall
>>>> socket (and less than 3dB between adjacent channels).
>>> Yes that's right, but analogue needed a s/n ratio roughly 20dB
>>>better
>>> than DTT, so in crude terms the delivered levels needed to be 20dB higher.
>>
>>> The old BBC advice was 1mV for BIV and 1.5mV for BV.
>> which was arrived at after testing a number of sets.
>
>Phew! Glad I remembered it right! Forgot you were here Charles!
>
> >Interestingly, tuner
>> became less sensitive with newer models.
>Specially a certain run of Sonys in the 1980s which needed a masthead
>amp if the aerial signals were below 66dBuV.
>
Yet in the 1970s, I remember that on the fifth floor of the EMI
>>>> socket (and less than 3dB between adjacent channels).
>>> Yes that's right, but analogue needed a s/n ratio roughly 20dB
>>>better
>>> than DTT, so in crude terms the delivered levels needed to be 20dB higher.
>>
>>> The old BBC advice was 1mV for BIV and 1.5mV for BV.
>> which was arrived at after testing a number of sets.
>
>Phew! Glad I remembered it right! Forgot you were here Charles!
>
> >Interestingly, tuner
>> became less sensitive with newer models.
>Specially a certain run of Sonys in the 1980s which needed a masthead
>amp if the aerial signals were below 66dBuV.
>
Engineering Building, in Hayes, Middlesex, the lab Sony 1310UB used to
get 19 nineteen channels without an aerial (and I think that was before
we had Channel 4).
--
Ian
Steve Thackery
Nov 26, 2011, 4:59:21 AM11/26/11
to
J G Miller wrote:
> Sorry if this seems like an impertinent and irrelevant question,
> but does it matter if the light is incandescent, fluorescent,
> CFL, or LED?
I've got a few light fittings that use low voltage halogens, and thus
> Sorry if this seems like an impertinent and irrelevant question,
> but does it matter if the light is incandescent, fluorescent,
> CFL, or LED?
have switched mode power supplies. They do seem a bit "dirty" at times
- the one in the kitchen drives several halogens, and when two or three
of the bulbs have failed (so the power supply is running at part load)
it generates enough squeal to wipe out my X10 home control system
(mains-borne signals).
Having said that, X10 works at pretty low frequencies compared to what*
we're talking about, so this contribution is probably not very helpful.
:-)
SteveT
*"that which", I should say, if I want to keep Mrs Lesurf happy. :-)
--
SteveT
Jim Lesurf
Nov 26, 2011, 4:34:24 AM11/26/11
to
In article <9ja133...@mid.individual.net>, Mark Carver
is that a great deal of our 'technical and engineering' history tends to
evaporate as people retire or move on and systems are changed.
That was what prompted me some years ago to start writing about the history
of UK audio long before 'vintage' became popular in magazines. But the same
applies in other areas. Hence my feeling that the PCM/NICAM behind BBC
radio would be forgotten. I certainly didn't know a lot of what now is in
the page I've done, and lots more in the material I've been given.
FWIW I will also be giving a copy of the 'archive' of info to the Science
Museum London, and the National Museums Scotland as their curators also
have an interest in documentation for engineering. The SM do have the
original BH PCM coders. But I don't know if any museum has a decoder! And
they often lack the detailed info that simply was never in the basic
documents.
I did try a few times to locate someone in the BBC who was a curator or
archivist for 'engineering'. But there seems to be 'no such animal' these
days. :-/
<mark....@invalid.invalid> wrote:
> On 25/11/2011 16:55, Jim Lesurf wrote:
> >> I wonder how other European national broadcasters, (some with
> >> geographical spreads that dwarf ours) dealt with the challenge in the
> >> 1970s ?
> >
> > I'm also curious about that, but have no idea of the answer(s).
> On 25/11/2011 16:55, Jim Lesurf wrote:
> >> I wonder how other European national broadcasters, (some with
> >> geographical spreads that dwarf ours) dealt with the challenge in the
> >> 1970s ?
> >
> > I'm also curious about that, but have no idea of the answer(s).
> I often visit foreign national broadcasters, I must start asking them
> these questions !
I would encourage you and others to do things like that. My general concern
> these questions !
is that a great deal of our 'technical and engineering' history tends to
evaporate as people retire or move on and systems are changed.
That was what prompted me some years ago to start writing about the history
of UK audio long before 'vintage' became popular in magazines. But the same
applies in other areas. Hence my feeling that the PCM/NICAM behind BBC
radio would be forgotten. I certainly didn't know a lot of what now is in
the page I've done, and lots more in the material I've been given.
FWIW I will also be giving a copy of the 'archive' of info to the Science
Museum London, and the National Museums Scotland as their curators also
have an interest in documentation for engineering. The SM do have the
original BH PCM coders. But I don't know if any museum has a decoder! And
they often lack the detailed info that simply was never in the basic
documents.
I did try a few times to locate someone in the BBC who was a curator or
archivist for 'engineering'. But there seems to be 'no such animal' these
days. :-/
tony sayer
Nov 26, 2011, 5:10:55 AM11/26/11
to
In article <4ed09a8...@news.eternal-september.org>, Don Pearce
Ah!... FWIW we have been using 5.8 Ghz extensively in recent times but
that will do the distance, we have one link 18 miles but clear LOS and
a thruput of in excess of 10 M/Bits but put ONE Leylandii in the way of
one some Hundreds of meters and .....
... Zilch .....
--
Tony Sayer
that will do the distance, we have one link 18 miles but clear LOS and
a thruput of in excess of 10 M/Bits but put ONE Leylandii in the way of
one some Hundreds of meters and .....
... Zilch .....
--
Tony Sayer
tony sayer
Nov 26, 2011, 5:12:39 AM11/26/11
to
In article <9jah2f...@mid.individual.net>, David Looser
<david....@btinternet.com> scribeth thus
The cellphone boys use that sort of frequency for short "ish" hops that
seem to work rather well....
--
Tony Sayer
<david....@btinternet.com> scribeth thus
seem to work rather well....
--
Tony Sayer
tony sayer
Nov 26, 2011, 5:21:45 AM11/26/11
to
In article <52381f3...@audiomisc.co.uk>, Jim Lesurf
<no...@audiomisc.co.uk> scribeth thus
a dual BB link. Nothing quite like a working exhibit....
If they can find a decoder of course;)..
>I did try a few times to locate someone in the BBC who was a curator or
>archivist for 'engineering'. But there seems to be 'no such animal' these
>days. :-/
>
If there ever was one that is..
>Slainte,
>
>Jim
>
--
Tony Sayer
<no...@audiomisc.co.uk> scribeth thus
>In article <9ja133...@mid.individual.net>, Mark Carver
><mark....@invalid.invalid> wrote:
>> On 25/11/2011 16:55, Jim Lesurf wrote:
>> >> I wonder how other European national broadcasters, (some with
>> >> geographical spreads that dwarf ours) dealt with the challenge in the
>> >> 1970s ?
>> >
>> > I'm also curious about that, but have no idea of the answer(s).
>
>> I often visit foreign national broadcasters, I must start asking them
>> these questions !
>
>I would encourage you and others to do things like that. My general concern
>is that a great deal of our 'technical and engineering' history tends to
>evaporate as people retire or move on and systems are changed.
>
>That was what prompted me some years ago to start writing about the history
>of UK audio long before 'vintage' became popular in magazines. But the same
>applies in other areas. Hence my feeling that the PCM/NICAM behind BBC
>radio would be forgotten. I certainly didn't know a lot of what now is in
>the page I've done, and lots more in the material I've been given.
>
>FWIW I will also be giving a copy of the 'archive' of info to the Science
>Museum London, and the National Museums Scotland as their curators also
>have an interest in documentation for engineering. The SM do have the
>original BH PCM coders. But I don't know if any museum has a decoder! And
>they often lack the detailed info that simply was never in the basic
>documents.
>
Umm ... One coder in Scotland and One decoder in London and run it over
><mark....@invalid.invalid> wrote:
>> On 25/11/2011 16:55, Jim Lesurf wrote:
>> >> I wonder how other European national broadcasters, (some with
>> >> geographical spreads that dwarf ours) dealt with the challenge in the
>> >> 1970s ?
>> >
>> > I'm also curious about that, but have no idea of the answer(s).
>
>> I often visit foreign national broadcasters, I must start asking them
>> these questions !
>
>I would encourage you and others to do things like that. My general concern
>is that a great deal of our 'technical and engineering' history tends to
>evaporate as people retire or move on and systems are changed.
>
>That was what prompted me some years ago to start writing about the history
>of UK audio long before 'vintage' became popular in magazines. But the same
>applies in other areas. Hence my feeling that the PCM/NICAM behind BBC
>radio would be forgotten. I certainly didn't know a lot of what now is in
>the page I've done, and lots more in the material I've been given.
>
>FWIW I will also be giving a copy of the 'archive' of info to the Science
>Museum London, and the National Museums Scotland as their curators also
>have an interest in documentation for engineering. The SM do have the
>original BH PCM coders. But I don't know if any museum has a decoder! And
>they often lack the detailed info that simply was never in the basic
>documents.
>
a dual BB link. Nothing quite like a working exhibit....
If they can find a decoder of course;)..
>I did try a few times to locate someone in the BBC who was a curator or
>archivist for 'engineering'. But there seems to be 'no such animal' these
>days. :-/
>
>Slainte,
>
>Jim
>
--
Tony Sayer
tony sayer
Nov 26, 2011, 5:31:41 AM11/26/11
to
In article <9jaq3h...@mid.individual.net>, Phil Allison
<phi...@tpg.com.au> scribeth thus
Back in the Summer the local community station Cambridge 105 fM was
covering a local Rock/Folk fest just outside Cambridge.
The main stage PA mixing left shall we say a lot to be desired but there
were some "off the main stage and later on in the evening impromptu
sessions of small folk bands.
They were broadcast with just a very simple mic arrangement not much
more than a crossed pair or similar. The signal was linked back to base
by a 5.8 G microwave link running full CD rate PCM. There it went
straight to another link to the TX and prolly the only station to have
one in the country, into the Harris digit FM TX on its AES input.
The processor was set to classical limit and the sound was simply
stunning, here with an Audiolab T8000 tuner and listened to on the
little ole LS3/5A's
Yep I'm sure it would have been that bit better on the ESL63's but it
was fine on those, in fact better then fine, just as near as it might
get to being there!...
>
>
>
>
--
Tony Sayer
<phi...@tpg.com.au> scribeth thus
covering a local Rock/Folk fest just outside Cambridge.
The main stage PA mixing left shall we say a lot to be desired but there
were some "off the main stage and later on in the evening impromptu
sessions of small folk bands.
They were broadcast with just a very simple mic arrangement not much
more than a crossed pair or similar. The signal was linked back to base
by a 5.8 G microwave link running full CD rate PCM. There it went
straight to another link to the TX and prolly the only station to have
one in the country, into the Harris digit FM TX on its AES input.
The processor was set to classical limit and the sound was simply
stunning, here with an Audiolab T8000 tuner and listened to on the
little ole LS3/5A's
Yep I'm sure it would have been that bit better on the ESL63's but it
was fine on those, in fact better then fine, just as near as it might
get to being there!...
>
>
>
>
--
Tony Sayer
Don Pearce
Nov 26, 2011, 5:41:10 AM11/26/11
to
On Sat, 26 Nov 2011 10:10:55 +0000, tony sayer <to...@bancom.co.uk>
Don't I know it. I was involved in wireless local loop at 3.5GHz in
the 1980s. Never worked properly. But just before last Christmas I
took a prototype Ka unit down to Goonhilly for trials. The satellite
wasn't yet in its proper orbital slot - right on the horizon, so the
guys thought we might not even find it. On the contrary, half an hour
later we had a solid 50Mbits/sec video stream running.
d
the 1980s. Never worked properly. But just before last Christmas I
took a prototype Ka unit down to Goonhilly for trials. The satellite
wasn't yet in its proper orbital slot - right on the horizon, so the
guys thought we might not even find it. On the contrary, half an hour
later we had a solid 50Mbits/sec video stream running.
d
Bill Wright
Nov 26, 2011, 7:04:54 AM11/26/11
to
Bill
Bill Wright
Nov 26, 2011, 7:06:07 AM11/26/11
to
Bill
Don Pearce
Nov 26, 2011, 7:17:58 AM11/26/11
to
On Sat, 26 Nov 2011 12:04:54 +0000, Bill Wright <bi...@invalid.com>
d
wrote:
>Don Pearce wrote:
>> On Sat, 26 Nov 2011 01:12:17 +0000, Bill Wright <bi...@invalid.com>
>> wrote:
>>
>>> Don Pearce wrote:
>>>
>>>> Your point with the attenuator is well made, and I didn't think of
>>>> trying that. I can bring home a switched one and see how many dBs I
>>>> can dial in before the errors start appearing.
>>> Use a 75ohm one!
>>>
>>> Bill
>>
>> I have plenty of low loss 75 to 50 ohm matches.
>
>Or if they fail you could try rubbing two sticks together...
>
TaDa!
>Don Pearce wrote:
>> On Sat, 26 Nov 2011 01:12:17 +0000, Bill Wright <bi...@invalid.com>
>> wrote:
>>
>>> Don Pearce wrote:
>>>
>>>> Your point with the attenuator is well made, and I didn't think of
>>>> trying that. I can bring home a switched one and see how many dBs I
>>>> can dial in before the errors start appearing.
>>> Use a 75ohm one!
>>>
>>> Bill
>>
>> I have plenty of low loss 75 to 50 ohm matches.
>
>Or if they fail you could try rubbing two sticks together...
>
d
Jim Lesurf
Nov 26, 2011, 6:09:49 AM11/26/11
to
In article <XaOdnRl-YosIWlLT...@bt.com>, Steve Thackery
<nob...@nowhere.com> wrote:
> Jim Lesurf wrote:
> > The initial PCM was based on a mux of about 6Megs/sec
> Would that have been based on the American PCM hierarchy? They used 24
> channel, 1536kb/s PCM links, rather than the 32 channel, 2048kb/s
> systems used in Europe.
The PCM system used 6336 kb/sec for the transmitted multiplex. I'd need to
check with my sources (both written and the people) to be sure. I think
this was based on a GPO standard or something similar. But even if so, that
may be based on a USA standard for all I know or recall!
> It was common to bind four together to produce 6M/8M pipes.
> I did wonder if the initial kit was brought in from the US.
Depends what you cover with your "kit".
The BBC PCM coders/decoders and the associated mux/demux systems, etc,
were BBC designed/built. But the signals were then fed out to a combination
of GPO and BBC links for actual bearing. I don't know where the GPO
equipment came from.
I can't say more at present, but when I get a chance I'll see if I can find
out. I do have a lot of info on details - but it comes to well over 100
pages worth, and growing. It is also often conversational and so splits up
info. (And in some cases disagrees!)
When were the USA systems you refer to designed and brought into use?
<nob...@nowhere.com> wrote:
> Jim Lesurf wrote:
> > The initial PCM was based on a mux of about 6Megs/sec
> Would that have been based on the American PCM hierarchy? They used 24
> channel, 1536kb/s PCM links, rather than the 32 channel, 2048kb/s
> systems used in Europe.
The PCM system used 6336 kb/sec for the transmitted multiplex. I'd need to
check with my sources (both written and the people) to be sure. I think
this was based on a GPO standard or something similar. But even if so, that
may be based on a USA standard for all I know or recall!
> It was common to bind four together to produce 6M/8M pipes.
> I did wonder if the initial kit was brought in from the US.
Depends what you cover with your "kit".
The BBC PCM coders/decoders and the associated mux/demux systems, etc,
were BBC designed/built. But the signals were then fed out to a combination
of GPO and BBC links for actual bearing. I don't know where the GPO
equipment came from.
I can't say more at present, but when I get a chance I'll see if I can find
out. I do have a lot of info on details - but it comes to well over 100
pages worth, and growing. It is also often conversational and so splits up
info. (And in some cases disagrees!)
When were the USA systems you refer to designed and brought into use?
Jim Lesurf
Nov 26, 2011, 6:14:06 AM11/26/11
to
In article <cH$E$0IXuL...@bancom.co.uk>, tony sayer
<to...@bancom.co.uk>
wrote:
> The cellphone boys use that sort of frequency for short "ish" hops that
> seem to work rather well....
FWIW one of the last 'professional' projects I did was a series of
measurements on the signal propagation details at c36GHz to assess its
reliability and required power levels, etc, for links between mobile phone
base stations and network links. It can actually work well over long
distance *provided* you can maintain a clear line of sight. But 'serious'
weather can cause quite a marked loss.
You also have to be careful not to have too much antenna gain as the
effects of refractive index variations in the air is also noticable.
<to...@bancom.co.uk>
wrote:
> The cellphone boys use that sort of frequency for short "ish" hops that
> seem to work rather well....
measurements on the signal propagation details at c36GHz to assess its
reliability and required power levels, etc, for links between mobile phone
base stations and network links. It can actually work well over long
distance *provided* you can maintain a clear line of sight. But 'serious'
weather can cause quite a marked loss.
You also have to be careful not to have too much antenna gain as the
effects of refractive index variations in the air is also noticable.
Jim Lesurf
Nov 26, 2011, 6:16:52 AM11/26/11
to
In article <anUFHOJ5...@bancom.co.uk>, tony sayer
<to...@bancom.co.uk>
wrote:
So for a demo you could use that. But not the same as sending the mux and
then getting output from it.
But it would be nice if we had something like a coder and decoder at
mueseums in London and Edinburgh and could send between them. :-)
<to...@bancom.co.uk>
wrote:
> >FWIW I will also be giving a copy of the 'archive' of info to the
> >Science Museum London, and the National Museums Scotland as their
> >curators also have an interest in documentation for engineering. The SM
> >do have the original BH PCM coders. But I don't know if any museum has
> >a decoder! And they often lack the detailed info that simply was never
> >in the basic documents.
> >
> Umm ... One coder in Scotland and One decoder in London and run it over
> a dual BB link. Nothing quite like a working exhibit....
> If they can find a decoder of course;)..
IIRC the coder does have just *one* decoder included for monitor purposes.
> >Science Museum London, and the National Museums Scotland as their
> >curators also have an interest in documentation for engineering. The SM
> >do have the original BH PCM coders. But I don't know if any museum has
> >a decoder! And they often lack the detailed info that simply was never
> >in the basic documents.
> >
> Umm ... One coder in Scotland and One decoder in London and run it over
> a dual BB link. Nothing quite like a working exhibit....
> If they can find a decoder of course;)..
So for a demo you could use that. But not the same as sending the mux and
then getting output from it.
But it would be nice if we had something like a coder and decoder at
mueseums in London and Edinburgh and could send between them. :-)
Don Pearce
Nov 26, 2011, 7:37:47 AM11/26/11
to
On Sat, 26 Nov 2011 11:14:06 +0000 (GMT), Jim Lesurf
<no...@audiomisc.co.uk> wrote:
>In article <cH$E$0IXuL...@bancom.co.uk>, tony sayer
><to...@bancom.co.uk>
>wrote:
>
>
>> The cellphone boys use that sort of frequency for short "ish" hops that
>> seem to work rather well....
>
>FWIW one of the last 'professional' projects I did was a series of
>measurements on the signal propagation details at c36GHz to assess its
>reliability and required power levels, etc, for links between mobile phone
>base stations and network links. It can actually work well over long
>distance *provided* you can maintain a clear line of sight. But 'serious'
>weather can cause quite a marked loss.
>
>You also have to be careful not to have too much antenna gain as the
>effects of refractive index variations in the air is also noticable.
>
>Slainte,
>
>Jim
I used to teach a course on microwave link design. It covered earth
<no...@audiomisc.co.uk> wrote:
>In article <cH$E$0IXuL...@bancom.co.uk>, tony sayer
><to...@bancom.co.uk>
>wrote:
>
>
>> The cellphone boys use that sort of frequency for short "ish" hops that
>> seem to work rather well....
>
>FWIW one of the last 'professional' projects I did was a series of
>measurements on the signal propagation details at c36GHz to assess its
>reliability and required power levels, etc, for links between mobile phone
>base stations and network links. It can actually work well over long
>distance *provided* you can maintain a clear line of sight. But 'serious'
>weather can cause quite a marked loss.
>
>You also have to be careful not to have too much antenna gain as the
>effects of refractive index variations in the air is also noticable.
>
>Slainte,
>
>Jim
diffraction, knife edge diffraction, Fresnel Zone clearance, rain
fade, flat fade, tropospheric scatter etc. During the course the
students would slowly build a spreadsheet that would be a tool they
could use later for link specification. It took a week to complete.
The problem now is that everybody just uses a computer programme and
understands none of the mechanisms they are dealing with. When things
turn out bad, they have no idea why.
d
charles
Nov 26, 2011, 8:30:49 AM11/26/11
to
In article <52381f3...@audiomisc.co.uk>, Jim Lesurf
who were going to create a broadcasting section. It was stored, for
safekeeping, in the old tram depot. Then it was decided to "improve" the
road system in the city and the tram depot had to be demolished. The BBC
took one large van to Bristol to collect what was deemed worth keeping. I
do remember a Disc Recorder that went on the Normandy Landings, but
everything else is a blur. This stuff was taken to Crowsley Park (the
annex of BBC Caversham). I'm guessing early 80s. I've no idea what happened
to it after that. Some other old kit ended up at Wood Norton.
As you can tell, I can remember a lot of useless facts
--
From KT24
Using a RISC OS computer running v5.16
tony sayer
Nov 26, 2011, 8:19:11 AM11/26/11
to
>
>IIRC the coder does have just *one* decoder included for monitor purposes.
>So for a demo you could use that. But not the same as sending the mux and
>then getting output from it.
>
>But it would be nice if we had something like a coder and decoder at
>mueseums in London and Edinburgh and could send between them. :-)
>
>Slainte,
Wasn't that that where the original demo's were done from, or was it to
>IIRC the coder does have just *one* decoder included for monitor purposes.
>So for a demo you could use that. But not the same as sending the mux and
>then getting output from it.
>
>But it would be nice if we had something like a coder and decoder at
>mueseums in London and Edinburgh and could send between them. :-)
>
>Slainte,
Glasgow?..
>
>Jim
>
--
Tony Sayer
tony sayer
Nov 26, 2011, 8:20:30 AM11/26/11
to
In article <4ed0dcb7...@news.eternal-september.org>, Don Pearce
<sp...@spam.com> scribeth thus
Still no substitute for having a butchers at the link, to see what's in
the way and what's likely to grow in the way;!...
--
Tony Sayer
<sp...@spam.com> scribeth thus
the way and what's likely to grow in the way;!...
--
Tony Sayer
Don Pearce
Nov 26, 2011, 8:50:06 AM11/26/11
to
On Sat, 26 Nov 2011 13:20:30 +0000, tony sayer <to...@bancom.co.uk>
wrote:
My hardest -to-design links have all been in the middle East. The
worst was half over desert and half over the sea. A dual nightmare for
two different reasons. The desert is really nasty at dawn and dusk
when the air stratifies badly and causes severe dips in signal level.
The sea does something similar but in response to tides.
Stuff getting in the way has never really been an issue.
d
wrote:
worst was half over desert and half over the sea. A dual nightmare for
two different reasons. The desert is really nasty at dawn and dusk
when the air stratifies badly and causes severe dips in signal level.
The sea does something similar but in response to tides.
Stuff getting in the way has never really been an issue.
d
Bill Wright
Nov 26, 2011, 9:29:42 AM11/26/11
to
Steve Thackery wrote:
> *"that which", I should say, if I want to keep Mrs Lesurf happy. :-)
>
"...the thing of which we speak..."?
> *"that which", I should say, if I want to keep Mrs Lesurf happy. :-)
>
Bill
Bill Wright
Nov 26, 2011, 9:40:04 AM11/26/11
to
Jim Lesurf wrote:
> FWIW one of the last 'professional' projects I did was a series of
> measurements on the signal propagation details at c36GHz
I think I need new glasses. I read that as 336GHz. I thought, "Surely
> FWIW one of the last 'professional' projects I did was a series of
> measurements on the signal propagation details at c36GHz
even Jim cannot ascend to such heights!"
Bill
Bill Wright
Nov 26, 2011, 9:42:25 AM11/26/11
to
Don Pearce wrote:
> The problem now is that everybody just uses a computer programme and
> understands none of the mechanisms they are dealing with. When things
> turn out bad, they have no idea why.
Well at least provides a training for life.
> The problem now is that everybody just uses a computer programme and
> understands none of the mechanisms they are dealing with. When things
> turn out bad, they have no idea why.
Bill
Bill Wright
Nov 26, 2011, 9:44:00 AM11/26/11
to
charles wrote:
> As you can tell, I can remember a lot of useless facts
But where the hell did you leave your glasses?
> As you can tell, I can remember a lot of useless facts
Bill
charles
Nov 26, 2011, 9:51:11 AM11/26/11
to
In article <jaqtvo$bek$3...@speranza.aioe.org>,
That's easy. I don't take them off, except when in bed, or having a bath.
Jim Lesurf
Nov 26, 2011, 11:14:28 AM11/26/11
to
In article <jaqtoc$bek$1...@speranza.aioe.org>, Bill Wright
Not for OfCom (actually for the old Radcom Agency). :-)
<ahem> Although it depends what your "heights" refers to...
If you mean frequency...
A lot of my work has involved frequencies up to and above 336GHz.
Even c1980 I was working on systems that worked at about 345GHz. This was
because there was a lot of interest in mapping intersteller clouds at the
time and one of the best ways was to detect the carbon monoxide lines at
115 / 230 / 345 GHz.
Mind you, we couldn't use diode mixers for 300-500 GHz back then. We had to
use liquid-Helium cooled Indium Antimonide.
If you mean altitude, the the Mauna Kea observatory is at about 14,000 ft.
So still enough air to breath if you take care. However, the first
research work I did was at about 60,000 ft.
http://jcgl.orpheusweb.co.uk/history/concorde/ChaseTheSun.html
That was fun. :-)
<ahem> Although it depends what your "heights" refers to...
If you mean frequency...
A lot of my work has involved frequencies up to and above 336GHz.
Even c1980 I was working on systems that worked at about 345GHz. This was
because there was a lot of interest in mapping intersteller clouds at the
time and one of the best ways was to detect the carbon monoxide lines at
115 / 230 / 345 GHz.
Mind you, we couldn't use diode mixers for 300-500 GHz back then. We had to
use liquid-Helium cooled Indium Antimonide.
If you mean altitude, the the Mauna Kea observatory is at about 14,000 ft.
So still enough air to breath if you take care. However, the first
research work I did was at about 60,000 ft.
http://jcgl.orpheusweb.co.uk/history/concorde/ChaseTheSun.html
That was fun. :-)
Bill Wright
Nov 26, 2011, 12:58:58 PM11/26/11
to
charles wrote:
> In article <jaqtvo$bek$3...@speranza.aioe.org>,
> Bill Wright <bi...@invalid.com> wrote:
>> charles wrote:
>
>>> As you can tell, I can remember a lot of useless facts
>
>> But where the hell did you leave your glasses?
>
> That's easy. I don't take them off, except when in bed, or having a bath.
>
Many years ago I was keen on a girl, and in the early stages of chatting
> In article <jaqtvo$bek$3...@speranza.aioe.org>,
> Bill Wright <bi...@invalid.com> wrote:
>> charles wrote:
>
>>> As you can tell, I can remember a lot of useless facts
>
>> But where the hell did you leave your glasses?
>
> That's easy. I don't take them off, except when in bed, or having a bath.
>
her up. She suddenly said, "Could you tell me something about yourself?
Something a bit personal?"
Of course you can't really say no, can you? So she went on, "Do you take
your glasses off when you have sex?"
I knew that there's be a right and a wrong answer. But I hedged my bets
and replied, "Which do you prefer?"
"Well you tell me whether or not you take them off and then I'll tell
you my preferences."
I answered, "If you want to find out it could be arranged."
I'll draw a veil at that point.
Bill
Bill Wright
Nov 26, 2011, 1:04:56 PM11/26/11
to
Jim Lesurf wrote:
> However, the first
> research work I did was at about 60,000 ft.
What a marvellous adventure!
> However, the first
> research work I did was at about 60,000 ft.
(file name for jpg is a bit rude about that bloke's nose though!)
Bill
Graham.
Nov 26, 2011, 3:34:05 PM11/26/11
to
On 25/11/2011 22:18, SpamTrapSeeSig wrote:
> In article <jaolu2$qsn$1...@profound-observation.eternal-september.org>,
> Graham. <m...@privacy.net> writes
>> On 25/11/2011 15:56, J G Miller wrote:
>>> On Friday, November 25th, 2011, at 12:53:56h +0000, Bill Wright wrote:
>>>
>>>> I have a twenty quid Currys Essentials box on my bench that is
>>>> working on 26dBuV. There are occasional glitches. The box has a
>>>> duckfit if I turn the light on.
>>>
>>> Sorry if this seems like an impertinent and irrelevant question,
>>> but does it matter if the light is incandescent, fluorescent,
>>> CFL, or LED?
>>>
>>> Or is it the switch its-self?
>>
>> I had a VHS tape that would stop playing if a light was turned on,
>> and it mattered not whether it was LED, GLS, CFL, gas or oil.
>> This isn't a joke, I'll see if you can solve the puzzle though.
>
> Did it have a transparent plastic case, by any chance?
>
> 19 questions left...
Translucent yellow IIRC.
--
Graham.
%Profound_observation%
> In article <jaolu2$qsn$1...@profound-observation.eternal-september.org>,
> Graham. <m...@privacy.net> writes
>> On 25/11/2011 15:56, J G Miller wrote:
>>> On Friday, November 25th, 2011, at 12:53:56h +0000, Bill Wright wrote:
>>>
>>>> I have a twenty quid Currys Essentials box on my bench that is
>>>> working on 26dBuV. There are occasional glitches. The box has a
>>>> duckfit if I turn the light on.
>>>
>>> Sorry if this seems like an impertinent and irrelevant question,
>>> but does it matter if the light is incandescent, fluorescent,
>>> CFL, or LED?
>>>
>>> Or is it the switch its-self?
>>
>> I had a VHS tape that would stop playing if a light was turned on,
>> and it mattered not whether it was LED, GLS, CFL, gas or oil.
>> This isn't a joke, I'll see if you can solve the puzzle though.
>
> Did it have a transparent plastic case, by any chance?
>
> 19 questions left...
Translucent yellow IIRC.
--
Graham.
%Profound_observation%
Graham.
Nov 26, 2011, 3:41:54 PM11/26/11
to
On 25/11/2011 18:49, Mark Carver wrote:
> On 25/11/2011 18:42, J G Miller wrote:
>> player?
>>
>> Something to do with the infra red control on the machine?
>
> Assuming a particular deck, Optical sensor for the tape end ? Light was
> leaking into the machine, and triggering the tape transport to stop ?
Precisely that.
The machine was a Hitachi top loader and the tape was a pre recorded one
in a yellow translucent cassette of cartoons belonging to my daughter.
--
Graham.
%Profound_observation%
> On 25/11/2011 18:42, J G Miller wrote:
>> On Friday, November 25th, 2011 at 18:14:33h +0000, Graham. wrote:
>>
>>> I had a VHS tape that would stop playing if a light was turned on
>>
>> A particular VHS cassette, or do you mean a particular VHS cassette
>>
>>> I had a VHS tape that would stop playing if a light was turned on
>>
>> player?
>>
>> Something to do with the infra red control on the machine?
>
> Assuming a particular deck, Optical sensor for the tape end ? Light was
> leaking into the machine, and triggering the tape transport to stop ?
Precisely that.
The machine was a Hitachi top loader and the tape was a pre recorded one
in a yellow translucent cassette of cartoons belonging to my daughter.
--
Graham.
%Profound_observation%
Message has been deleted
tony sayer
Nov 26, 2011, 5:46:43 PM11/26/11
to
In article <4ed0ee10...@news.eternal-september.org>, Don Pearce
Lucky You!. Not the same in urban areas or worse still the leafy
suburbs. I know that one outfit was going to start a wireless broadband
service in this area using I believe either 4 or 6 odd Ghz but it fell
through because of the attenuation of "urban clutter" ...
>
>d
--
Tony Sayer
suburbs. I know that one outfit was going to start a wireless broadband
service in this area using I believe either 4 or 6 odd Ghz but it fell
through because of the attenuation of "urban clutter" ...
>
>d
--
Tony Sayer
Brian Gregory [UK]
Nov 26, 2011, 7:42:21 PM11/26/11
to
"Don Pearce" <sp...@spam.com> wrote in message
news:4ed0cdad...@news.eternal-september.org...
> On Fri, 25 Nov 2011 15:18:58 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
>
>>In article <4ecfaa64...@news.eternal-september.org>, Don Pearce
>><sp...@spam.com> wrote:
>>> On Fri, 25 Nov 2011 14:18:30 +0000 (GMT), Jim Lesurf
>>> <no...@audiomisc.co.uk> wrote:
>>
>>> >In article <5237a0c...@davenoise.co.uk>, Dave Plowman (News)
>>> ><da...@davenoise.co.uk> wrote:
>>> >> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
>>> >> <no...@audiomisc.co.uk> wrote:
>>> >> > > Would you check the end of the second paragraph from the top?
>>> >
>>> >> > Ah. You mean it should read more like "sound quality was quite
>>> >> > inferior *to* what we"
>>> >
>>> >> Yup.
>>> >
>>> >Now fixed that and some other typos and late corrections from 'the
>>> >engineers'. :-)
>>
>>
>>> Still doesn't look right - missing the "what". Or isn't it uploaded yet?
>>
>>Boooger. I'll fix that. Your pointing this out also prompted a flurry
>>of argument between me and 'higher management' (my wife) over the
>>alternative "that which" phrasing, but I prefer "what".
>>
>>Jim
>
> Maybe technically correct, but "that which" is awfully clumsy. I'd go
> for the fluent read every time.
... the sound quality was quite inferior to what's expected today.
Sound most fluent and correct to me.
--
Brian Gregory. (In the UK)
n...@bgdsv.co.uk
To email me remove the letter vee.
news:4ed0cdad...@news.eternal-september.org...
> On Fri, 25 Nov 2011 15:18:58 +0000 (GMT), Jim Lesurf
> <no...@audiomisc.co.uk> wrote:
>
>>In article <4ecfaa64...@news.eternal-september.org>, Don Pearce
>><sp...@spam.com> wrote:
>>> On Fri, 25 Nov 2011 14:18:30 +0000 (GMT), Jim Lesurf
>>> <no...@audiomisc.co.uk> wrote:
>>
>>> >In article <5237a0c...@davenoise.co.uk>, Dave Plowman (News)
>>> ><da...@davenoise.co.uk> wrote:
>>> >> In article <5237966...@audiomisc.co.uk>, Jim Lesurf
>>> >> <no...@audiomisc.co.uk> wrote:
>>> >> > > Would you check the end of the second paragraph from the top?
>>> >
>>> >> > Ah. You mean it should read more like "sound quality was quite
>>> >> > inferior *to* what we"
>>> >
>>> >> Yup.
>>> >
>>> >Now fixed that and some other typos and late corrections from 'the
>>> >engineers'. :-)
>>
>>
>>> Still doesn't look right - missing the "what". Or isn't it uploaded yet?
>>
>>Boooger. I'll fix that. Your pointing this out also prompted a flurry
>>of argument between me and 'higher management' (my wife) over the
>>alternative "that which" phrasing, but I prefer "what".
>>
>>Jim
>
> Maybe technically correct, but "that which" is awfully clumsy. I'd go
> for the fluent read every time.
... the sound quality was quite inferior to what's expected today.
Sound most fluent and correct to me.
--
Brian Gregory. (In the UK)
n...@bgdsv.co.uk
To email me remove the letter vee.
Dave Plowman (News)
Nov 26, 2011, 7:46:40 PM11/26/11
to
In article <og68q8-...@wschwanke.de>,
Wolfgang Schwanke <s...@sig.nature> wrote:
> FM in Germany was introduced as early as the late 1940s and was
> gradually upgraded to stereo in the 1960s and 70s. All stations had
> their own FM transmitter chain very much from the start, which is why
> AM listening became unpopular a long time earlier than in the UK.
I understood there were no MW (or very few) frequencies allowed in Germany
after WW2 hastening the development of FM?
--
*Sleep with a photographer and watch things develop
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
Wolfgang Schwanke <s...@sig.nature> wrote:
> FM in Germany was introduced as early as the late 1940s and was
> gradually upgraded to stereo in the 1960s and 70s. All stations had
> their own FM transmitter chain very much from the start, which is why
> AM listening became unpopular a long time earlier than in the UK.
I understood there were no MW (or very few) frequencies allowed in Germany
after WW2 hastening the development of FM?
--
*Sleep with a photographer and watch things develop
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
charles
Nov 26, 2011, 7:53:42 PM11/26/11
to
> Jim Lesurf <no...@audiomisc.co.uk> wrote in
> news:5237c3b...@audiomisc.co.uk:
> > In article <9j9to8...@mid.individual.net>, Mark Carver
> microwave links between the transmitter towers carrying an analogue
> signal. I'm not aware of audible degradation in remote transmitters. If
> a station was in stereo, it was so in all of its coverage area from the
> start. The fact that there was (and is) no nationwide FM network, but
> only regional stations covering one state each may be of help as it
> keeps distances shorter. The links are most likely all digital now and
> may use satellite instead of terrestrial (you see I'm no expert ...),
> but digital was certainly not used 1970s.
> FM in Germany was introduced as early as the late 1940s and was
> gradually upgraded to stereo in the 1960s and 70s. All stations had
> their own FM transmitter chain very much from the start, which is why
> AM listening became unpopular a long time earlier than in the UK.
As I understood it, Germany was not allocated any medium wave frequencies
at the post-war conference, so had to use Band II.
> news:5237c3b...@audiomisc.co.uk:
> > In article <9j9to8...@mid.individual.net>, Mark Carver
> ><mark....@invalid.invalid> wrote:
> >> I wonder how other European national broadcasters, (some with
> >> geographical spreads that dwarf ours) dealt with the challenge in the
> >> 1970s ?
> >
> > I'm also curious about that, but have no idea of the answer(s).
> I'm no expert, but I think the West and East German broadcasters used
> >> I wonder how other European national broadcasters, (some with
> >> geographical spreads that dwarf ours) dealt with the challenge in the
> >> 1970s ?
> >
> > I'm also curious about that, but have no idea of the answer(s).
> microwave links between the transmitter towers carrying an analogue
> signal. I'm not aware of audible degradation in remote transmitters. If
> a station was in stereo, it was so in all of its coverage area from the
> start. The fact that there was (and is) no nationwide FM network, but
> only regional stations covering one state each may be of help as it
> keeps distances shorter. The links are most likely all digital now and
> may use satellite instead of terrestrial (you see I'm no expert ...),
> but digital was certainly not used 1970s.
> FM in Germany was introduced as early as the late 1940s and was
> gradually upgraded to stereo in the 1960s and 70s. All stations had
> their own FM transmitter chain very much from the start, which is why
> AM listening became unpopular a long time earlier than in the UK.
at the post-war conference, so had to use Band II.
Don Pearce
Nov 27, 2011, 2:56:41 AM11/27/11
to
On Sat, 26 Nov 2011 22:46:43 +0000, tony sayer <to...@bancom.co.uk>
wrote:
>Lucky You!. Not the same in urban areas or worse still the leafy
>suburbs. I know that one outfit was going to start a wireless broadband
>service in this area using I believe either 4 or 6 odd Ghz but it fell
>through because of the attenuation of "urban clutter" ...
>>
>>d
Well, yes I had exactly this problem with wireless local loop, but
that wasn't a case of designed links, just area coverage. In link
design, stuff that gets in the way is obvious and either avoided or
allowed for. It is never a problem in the sense that an apparently
good link design fails to work.
d
wrote:
>Lucky You!. Not the same in urban areas or worse still the leafy
>suburbs. I know that one outfit was going to start a wireless broadband
>service in this area using I believe either 4 or 6 odd Ghz but it fell
>through because of the attenuation of "urban clutter" ...
>>
>>d
that wasn't a case of designed links, just area coverage. In link
design, stuff that gets in the way is obvious and either avoided or
allowed for. It is never a problem in the sense that an apparently
good link design fails to work.
d
David Looser
Nov 27, 2011, 4:38:27 AM11/27/11
to
"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
news:523872b...@davenoise.co.uk...
be an early European adopter of FM because the Allies had deprived it of the
number of MW channels needed for both national and regional broadcasting.
David.
news:523872b...@davenoise.co.uk...
> In article <og68q8-...@wschwanke.de>,
> Wolfgang Schwanke <s...@sig.nature> wrote:
>> FM in Germany was introduced as early as the late 1940s and was
>> gradually upgraded to stereo in the 1960s and 70s. All stations had
>> their own FM transmitter chain very much from the start, which is why
>> AM listening became unpopular a long time earlier than in the UK.
>
> I understood there were no MW (or very few) frequencies allowed in Germany
> after WW2 hastening the development of FM?
>
Indeed, that's very much my understanding too. Germany more or less had to
> Wolfgang Schwanke <s...@sig.nature> wrote:
>> FM in Germany was introduced as early as the late 1940s and was
>> gradually upgraded to stereo in the 1960s and 70s. All stations had
>> their own FM transmitter chain very much from the start, which is why
>> AM listening became unpopular a long time earlier than in the UK.
>
> I understood there were no MW (or very few) frequencies allowed in Germany
> after WW2 hastening the development of FM?
>
be an early European adopter of FM because the Allies had deprived it of the
number of MW channels needed for both national and regional broadcasting.
David.
David Looser
Nov 27, 2011, 4:40:06 AM11/27/11
to
"charles" <cha...@charleshope.demon.co.uk> wrote in message
news:52387359...@charleshope.demon.co.uk...
>
> As I understood it, Germany was not allocated any medium wave frequencies
> at the post-war conference, so had to use Band II.
>
It was allocated some, just not enough.
David.
news:52387359...@charleshope.demon.co.uk...
>
> As I understood it, Germany was not allocated any medium wave frequencies
> at the post-war conference, so had to use Band II.
>
David.
Roderick Stewart
Nov 27, 2011, 4:58:30 AM11/27/11
to
Rod.
--
Virtual Access V6.3 free usenet/email software from
http://sourceforge.net/projects/virtual-access/
Jim Lesurf
Nov 27, 2011, 5:14:32 AM11/27/11
to
> Jim Lesurf <no...@audiomisc.co.uk> wrote in
> news:5237c3b...@audiomisc.co.uk:
> > In article <9j9to8...@mid.individual.net>, Mark Carver
> ><mark....@invalid.invalid> wrote:
> >> I wonder how other European national broadcasters, (some with
> >> geographical spreads that dwarf ours) dealt with the challenge in the
> >> 1970s ?
> >
> > I'm also curious about that, but have no idea of the answer(s).
> I'm no expert, but I think the West and East German broadcasters used
> microwave links between the transmitter towers carrying an analogue
> signal. I'm not aware of audible degradation in remote transmitters. If
> a station was in stereo, it was so in all of its coverage area from the
> start. The fact that there was (and is) no nationwide FM network, but
> only regional stations covering one state each may be of help as it
> keeps distances shorter. The links are most likely all digital now and
> may use satellite instead of terrestrial (you see I'm no expert ...),
> but digital was certainly not used 1970s.
Thanks for the above. I must confess it was Germany I had in mind when I
> news:5237c3b...@audiomisc.co.uk:
> > In article <9j9to8...@mid.individual.net>, Mark Carver
> ><mark....@invalid.invalid> wrote:
> >> I wonder how other European national broadcasters, (some with
> >> geographical spreads that dwarf ours) dealt with the challenge in the
> >> 1970s ?
> >
> > I'm also curious about that, but have no idea of the answer(s).
> I'm no expert, but I think the West and East German broadcasters used
> microwave links between the transmitter towers carrying an analogue
> signal. I'm not aware of audible degradation in remote transmitters. If
> a station was in stereo, it was so in all of its coverage area from the
> start. The fact that there was (and is) no nationwide FM network, but
> only regional stations covering one state each may be of help as it
> keeps distances shorter. The links are most likely all digital now and
> may use satellite instead of terrestrial (you see I'm no expert ...),
> but digital was certainly not used 1970s.
wrote...
> > Although I wonder if some countries may have 'solved' such problems by
> > simply having regional broadcasting, thus avoiding the need to send
> > good stereo audio over long distance distribution! :-)
:-) ...but I wasn't sure I was correct, or which other places may have
based FM on a 'regional' approach.
These days, of course, the BBC tend to inject their NICAM into an
'outsourced' bearer system, so don't necessarily even know the routes
involved. But provided the bearer systems work OK that becomes irrelevant
from the POV of sound quality.
In some ways the irony is that the closest we get to a 'direct' feed is the
iPlayer, despite the enthusiasm many audio fans continue to have for FM.
For something like a Prom on R3 they feed 48k/24bit back to Broadcasting
House. That is then converted into the required formats. Although FM gets
NICAM (32k sample rate and 14/10 bits/sample, with optimod) the iPlayer
gets 320kbps AAC+ at 44.1k/16bit (no optimod). IIUC they hope sometime to
change that 48k/16, so avoiding the rate conversion.
Fingers crossed that one day we'll get 48k/24bit FLAC from the iPlayer.
Until then the main limit tends to be that not everyone in the UK has an
adequate braodband link.
Slainte,
Dave Plowman (News)
Nov 27, 2011, 6:21:51 AM11/27/11
to
In article <df2dnehfSIvkGkzT...@giganews.com>,
Perhaps 'is possible'? ;-)
Plenty seem pretty happy with much poorer quality than should be the norm.
--
*Indian Driver - Smoke signals only*
Brian Gregory [UK] <n...@bgdsv.co.uk> wrote:
> > Maybe technically correct, but "that which" is awfully clumsy. I'd go
> > for the fluent read every time.
> ... the sound quality was quite inferior to what's expected today.
^^^^^^^^
> > Maybe technically correct, but "that which" is awfully clumsy. I'd go
> > for the fluent read every time.
> ... the sound quality was quite inferior to what's expected today.
Perhaps 'is possible'? ;-)
Plenty seem pretty happy with much poorer quality than should be the norm.
--
*Indian Driver - Smoke signals only*
Jim Lesurf
Nov 27, 2011, 8:31:37 AM11/27/11
to
In article <5238acd...@davenoise.co.uk>, Dave Plowman (News)
enough to readers who don't pause to try and pick apart the phrasing. As
they read the rest of the article it should be clear enough. However one of
the questions we discussed 'at home' was who was expecting what. But my
point was that people nowdays tend to take for granted that something like
'BBC FM' should/will sound the same (i.e. good) around the UK once you have
a decent tuner and are located where you can pick up a good VHF signal.
(Admittedly, two fairly demanding caveats given how many simply use a cheap
portable, etc. But I did write the article for those who have a serious
interest in audio and radio.)
Whereas, pre-PCM, many may not have realised if they lived well away from
London and Wrotham that the FM sound quality available to them in their
area was lower than in the SE of England. The situation with stereo did
bring this, literally, home to them... So public (and retail trade)
awareness that at the time stereo was so geographically limited acted as a
spur to finding a solution like PCM, and then NICAM.
Odd contrast to these days when the BBC Trust think it is fine to do things
like remove sound radio from a platform in Scotland without doing so at the
same time in England, etc! Poll Tax comes to mind... :-)
<da...@davenoise.co.uk> wrote:
> In article <df2dnehfSIvkGkzT...@giganews.com>, Brian
> Gregory [UK] <n...@bgdsv.co.uk> wrote:
> > > Maybe technically correct, but "that which" is awfully clumsy. I'd
> > > go for the fluent read every time.
> > ... the sound quality was quite inferior to what's expected today.
> ^^^^^^^^
> Perhaps 'is possible'? ;-)
> Plenty seem pretty happy with much poorer quality than should be the
> norm.
I'm currently happy with the wording as I think it makes my meaning clear
> In article <df2dnehfSIvkGkzT...@giganews.com>, Brian
> Gregory [UK] <n...@bgdsv.co.uk> wrote:
> > > Maybe technically correct, but "that which" is awfully clumsy. I'd
> > > go for the fluent read every time.
> > ... the sound quality was quite inferior to what's expected today.
> ^^^^^^^^
> Perhaps 'is possible'? ;-)
> Plenty seem pretty happy with much poorer quality than should be the
> norm.
enough to readers who don't pause to try and pick apart the phrasing. As
they read the rest of the article it should be clear enough. However one of
the questions we discussed 'at home' was who was expecting what. But my
point was that people nowdays tend to take for granted that something like
'BBC FM' should/will sound the same (i.e. good) around the UK once you have
a decent tuner and are located where you can pick up a good VHF signal.
(Admittedly, two fairly demanding caveats given how many simply use a cheap
portable, etc. But I did write the article for those who have a serious
interest in audio and radio.)
Whereas, pre-PCM, many may not have realised if they lived well away from
London and Wrotham that the FM sound quality available to them in their
area was lower than in the SE of England. The situation with stereo did
bring this, literally, home to them... So public (and retail trade)
awareness that at the time stereo was so geographically limited acted as a
spur to finding a solution like PCM, and then NICAM.
Odd contrast to these days when the BBC Trust think it is fine to do things
like remove sound radio from a platform in Scotland without doing so at the
same time in England, etc! Poll Tax comes to mind... :-)
tony sayer
Nov 27, 2011, 11:58:54 AM11/27/11
to
> :-) ...but I wasn't sure I was correct, or which other places may have
>based FM on a 'regional' approach.
>
>These days, of course, the BBC tend to inject their NICAM into an
>'outsourced' bearer system, so don't necessarily even know the routes
>involved. But provided the bearer systems work OK that becomes irrelevant
>from the POV of sound quality.
>
>In some ways the irony is that the closest we get to a 'direct' feed is the
>iPlayer, despite the enthusiasm many audio fans continue to have for FM.
Well can't you hear that metallic sheen on the DAB service?. Course the
>based FM on a 'regional' approach.
>
>These days, of course, the BBC tend to inject their NICAM into an
>'outsourced' bearer system, so don't necessarily even know the routes
>involved. But provided the bearer systems work OK that becomes irrelevant
>from the POV of sound quality.
>
>In some ways the irony is that the closest we get to a 'direct' feed is the
>iPlayer, despite the enthusiasm many audio fans continue to have for FM.
direct feed could be classed as a landline feed and if you have a very
very quiet PC to decode that and feed it to your speakers then fine
provided your as Jim sez on a good broadband feed;!..
>
>For something like a Prom on R3 they feed 48k/24bit back to Broadcasting
>House. That is then converted into the required formats. Although FM gets
>NICAM (32k sample rate and 14/10 bits/sample, with optimod) the iPlayer
>gets 320kbps AAC+ at 44.1k/16bit (no optimod). IIUC they hope sometime to
>change that 48k/16, so avoiding the rate conversion.
>
>Fingers crossed that one day we'll get 48k/24bit FLAC from the iPlayer.
>Until then the main limit tends to be that not everyone in the UK has an
>adequate braodband link.
FLAC and very neat it is too;)..
>
>Slainte,
>
>Jim
>
--
Tony Sayer
Dave Plowman (News)
Nov 27, 2011, 2:28:39 PM11/27/11
to
In article <5238b8b...@audiomisc.co.uk>,
On national broadcasts, it sounded little different from our Truvox radio
'jack' - a crystal set. Until the odd occasion there was a local opt out.
Then, an extra octave or so appeared as if by magic.
--
*The problem with the world is that everyone is a few drinks behind *
Jim Lesurf <no...@audiomisc.co.uk> wrote:
> Whereas, pre-PCM, many may not have realised if they lived well away from
> London and Wrotham that the FM sound quality available to them in their
> area was lower than in the SE of England. The situation with stereo did
> bring this, literally, home to them... So public (and retail trade)
> awareness that at the time stereo was so geographically limited acted as a
> spur to finding a solution like PCM, and then NICAM.
I well remember our first FM tuner in Aberdeen - late '50s or early '60s.
> Whereas, pre-PCM, many may not have realised if they lived well away from
> London and Wrotham that the FM sound quality available to them in their
> area was lower than in the SE of England. The situation with stereo did
> bring this, literally, home to them... So public (and retail trade)
> awareness that at the time stereo was so geographically limited acted as a
> spur to finding a solution like PCM, and then NICAM.
On national broadcasts, it sounded little different from our Truvox radio
'jack' - a crystal set. Until the odd occasion there was a local opt out.
Then, an extra octave or so appeared as if by magic.
--
*The problem with the world is that everyone is a few drinks behind *
Andy Champ
Nov 27, 2011, 2:48:42 PM11/27/11
to
On 26/11/2011 16:14, Jim Lesurf wrote:
>
> Not for OfCom (actually for the old Radcom Agency). :-)
>
> <ahem> Although it depends what your "heights" refers to...
>
> If you mean frequency...
>
> A lot of my work has involved frequencies up to and above 336GHz.
>
> Even c1980 I was working on systems that worked at about 345GHz. This was
> because there was a lot of interest in mapping intersteller clouds at the
> time and one of the best ways was to detect the carbon monoxide lines at
> 115 / 230 / 345 GHz.
>
> Mind you, we couldn't use diode mixers for 300-500 GHz back then. We had to
> use liquid-Helium cooled Indium Antimonide.
>
> If you mean altitude, the the Mauna Kea observatory is at about 14,000 ft.
> So still enough air to breath if you take care. However, the first
> research work I did was at about 60,000 ft.
>
> http://jcgl.orpheusweb.co.uk/history/concorde/ChaseTheSun.html
>
> That was fun. :-)
>
> Jim
>
Fascinating. And I'm jealous - I only ever went on Concorde once, and I
>
> Not for OfCom (actually for the old Radcom Agency). :-)
>
> <ahem> Although it depends what your "heights" refers to...
>
> If you mean frequency...
>
> A lot of my work has involved frequencies up to and above 336GHz.
>
> Even c1980 I was working on systems that worked at about 345GHz. This was
> because there was a lot of interest in mapping intersteller clouds at the
> time and one of the best ways was to detect the carbon monoxide lines at
> 115 / 230 / 345 GHz.
>
> Mind you, we couldn't use diode mixers for 300-500 GHz back then. We had to
> use liquid-Helium cooled Indium Antimonide.
>
> If you mean altitude, the the Mauna Kea observatory is at about 14,000 ft.
> So still enough air to breath if you take care. However, the first
> research work I did was at about 60,000 ft.
>
> http://jcgl.orpheusweb.co.uk/history/concorde/ChaseTheSun.html
>
> That was fun. :-)
>
> Jim
>
had to pay for it!
Minor point - "a dewer of 100 litres of Liquid Helium" - that's Dewar.
Andy
J. P. Gilliver (John)
Nov 27, 2011, 5:26:02 PM11/27/11
to
In message <9jeeol...@mid.individual.net>, David Looser
Why? Just because they could, or they wanted it for the American Forces
Network, or what? (Certainly not BFBS - that was FM only.)
>
>
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf
Does God believe in people?
Network, or what? (Certainly not BFBS - that was FM only.)
>
>
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf
Does God believe in people?
Message has been deleted
David Looser
Nov 28, 2011, 3:05:42 AM11/28/11
to
"Wolfgang Schwanke" <s...@sig.nature> wrote in message
news:1lkbq8-...@wschwanke.de...
> "J. P. Gilliver (John)" <G6...@soft255.demon.co.uk> wrote in
> news:EMlROSb6...@soft255.demon.co.uk:
> Well, because Germany lost the war. :) And because the nazis had hogged
> so many frequencies for their propaganda broadcasts. It must have been
> somewhat like Soviet broadcasts during the cold war, if not worse.
>
> AFN used only one or two AM frequencies actually, they had FM
> transmitters as well.
>
The medium wave band had become pretty chaotic in Europe in the 1930s, with
transmitters powers increasing dramatically during the decade so that
co-channel interference, particularly after dark, had become a real problem.
As Wolfgang says the Nazis were no respecters of international band-planning
agreements and had simply used whichever frequencies they wanted at whatever
power they could.
So in 1949 there was a real need to put European MW allocations back onto a
rational basis. Germany lost out in this process at least in part because it
had just lost a catastrophic war for which it was held responsible. In the
end, though, it could be argued that this did Germany a favour as it forced
it to become an early adopter of FM broadcasting.
David.
news:1lkbq8-...@wschwanke.de...
> "J. P. Gilliver (John)" <G6...@soft255.demon.co.uk> wrote in
> news:EMlROSb6...@soft255.demon.co.uk:
> so many frequencies for their propaganda broadcasts. It must have been
> somewhat like Soviet broadcasts during the cold war, if not worse.
>
> AFN used only one or two AM frequencies actually, they had FM
> transmitters as well.
>
The medium wave band had become pretty chaotic in Europe in the 1930s, with
transmitters powers increasing dramatically during the decade so that
co-channel interference, particularly after dark, had become a real problem.
As Wolfgang says the Nazis were no respecters of international band-planning
agreements and had simply used whichever frequencies they wanted at whatever
power they could.
So in 1949 there was a real need to put European MW allocations back onto a
rational basis. Germany lost out in this process at least in part because it
had just lost a catastrophic war for which it was held responsible. In the
end, though, it could be argued that this did Germany a favour as it forced
it to become an early adopter of FM broadcasting.
David.
J. P. Gilliver (John)
Nov 28, 2011, 3:47:44 AM11/28/11
to
In message <9jgtmn...@mid.individual.net>, David Looser
>end, though, it could be argued that this did Germany a favour as it forced
>it to become an early adopter of FM broadcasting.
Certainly I (vaguely) remember (I was brought up in Germany in the
1960s/'70s) there being more FM-only sets (and hifis and so on) than
here.
>
>David.
<david....@btinternet.com> writes:
>"Wolfgang Schwanke" <s...@sig.nature> wrote in message
>news:1lkbq8-...@wschwanke.de...
>> "J. P. Gilliver (John)" <G6...@soft255.demon.co.uk> wrote in
>> news:EMlROSb6...@soft255.demon.co.uk:
>>
>>> In message <9jeeol...@mid.individual.net>, David Looser
>>><david....@btinternet.com> writes:
>>>>"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
>>>>news:523872b...@davenoise.co.uk...
>>>>> In article <og68q8-...@wschwanke.de>,
>>>>> Wolfgang Schwanke <s...@sig.nature> wrote:
>>>>>> FM in Germany was introduced as early as the late 1940s and was
>>>>>> gradually upgraded to stereo in the 1960s and 70s. All stations had
>>>>>> their own FM transmitter chain very much from the start, which is
>>>>>> why AM listening became unpopular a long time earlier than in the
>>>>>> UK.
>>>>>
>>>>> I understood there were no MW (or very few) frequencies allowed in
>>>>> Germany after WW2 hastening the development of FM?
>>>>>
>>>>
>>>>Indeed, that's very much my understanding too. Germany more or less
>>>>had to be an early European adopter of FM because the Allies had
>>>>deprived it of the number of MW channels needed for both national and
>>>>regional broadcasting.
>>>>
>>>>David.
>>>>
>>>>
>>> Why? Just because they could, or they wanted it for the American
^^^^^^^^^^^^^^^^^^^^^^^
>"Wolfgang Schwanke" <s...@sig.nature> wrote in message
>news:1lkbq8-...@wschwanke.de...
>> "J. P. Gilliver (John)" <G6...@soft255.demon.co.uk> wrote in
>> news:EMlROSb6...@soft255.demon.co.uk:
>>
>>> In message <9jeeol...@mid.individual.net>, David Looser
>>><david....@btinternet.com> writes:
>>>>"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
>>>>news:523872b...@davenoise.co.uk...
>>>>> In article <og68q8-...@wschwanke.de>,
>>>>> Wolfgang Schwanke <s...@sig.nature> wrote:
>>>>>> FM in Germany was introduced as early as the late 1940s and was
>>>>>> gradually upgraded to stereo in the 1960s and 70s. All stations had
>>>>>> their own FM transmitter chain very much from the start, which is
>>>>>> why AM listening became unpopular a long time earlier than in the
>>>>>> UK.
>>>>>
>>>>> I understood there were no MW (or very few) frequencies allowed in
>>>>> Germany after WW2 hastening the development of FM?
>>>>>
>>>>
>>>>Indeed, that's very much my understanding too. Germany more or less
>>>>had to be an early European adopter of FM because the Allies had
>>>>deprived it of the number of MW channels needed for both national and
>>>>regional broadcasting.
>>>>
>>>>David.
>>>>
>>>>
>>> Why? Just because they could, or they wanted it for the American
>>> Forces Network, or what? (Certainly not BFBS - that was FM only.)
>>
>> Well, because Germany lost the war. :) And because the nazis had hogged
>> so many frequencies for their propaganda broadcasts. It must have been
>> somewhat like Soviet broadcasts during the cold war, if not worse.
>>
>> AFN used only one or two AM frequencies actually, they had FM
>> transmitters as well.
>>
>
>The medium wave band had become pretty chaotic in Europe in the 1930s, with
>transmitters powers increasing dramatically during the decade so that
>co-channel interference, particularly after dark, had become a real problem.
>As Wolfgang says the Nazis were no respecters of international band-planning
>agreements and had simply used whichever frequencies they wanted at whatever
>power they could.
>
>So in 1949 there was a real need to put European MW allocations back onto a
>rational basis. Germany lost out in this process at least in part because it
>had just lost a catastrophic war for which it was held responsible. In the
Ah, so it _was_ vindictiveness to at least some extent.
>>
>> Well, because Germany lost the war. :) And because the nazis had hogged
>> so many frequencies for their propaganda broadcasts. It must have been
>> somewhat like Soviet broadcasts during the cold war, if not worse.
>>
>> AFN used only one or two AM frequencies actually, they had FM
>> transmitters as well.
>>
>
>The medium wave band had become pretty chaotic in Europe in the 1930s, with
>transmitters powers increasing dramatically during the decade so that
>co-channel interference, particularly after dark, had become a real problem.
>As Wolfgang says the Nazis were no respecters of international band-planning
>agreements and had simply used whichever frequencies they wanted at whatever
>power they could.
>
>So in 1949 there was a real need to put European MW allocations back onto a
>rational basis. Germany lost out in this process at least in part because it
>had just lost a catastrophic war for which it was held responsible. In the
>end, though, it could be argued that this did Germany a favour as it forced
>it to become an early adopter of FM broadcasting.
1960s/'70s) there being more FM-only sets (and hifis and so on) than
here.
>
>David.
Jim Lesurf
Nov 28, 2011, 4:16:03 AM11/28/11
to
In article <j_WdnUDlwqiHCU_T...@eclipse.net.uk>, Andy
Champ
<no....@nospam.invalid> wrote:
[snip]
> Minor point - "a dewer of 100 litres of Liquid Helium" - that's Dewar.
Noted.
Slainte,
Champ
<no....@nospam.invalid> wrote:
[snip]
> Fascinating. And I'm jealous - I only ever went on Concorde once, and I
> had to pay for it!
I never went on a Concorde with normal seating and cabin service! :-)
> had to pay for it!
> Minor point - "a dewer of 100 litres of Liquid Helium" - that's Dewar.
Slainte,
Terry Casey
Nov 28, 2011, 5:08:09 AM11/28/11
to
In article <1lkbq8-...@wschwanke.de>, s...@sig.nature says...
received in the UK in the 60s.
Plus, at closedown, a very long list of relay transmitters would be read
out, all with AM frequencies.
[1] Frankfurt, Munich and Stuttgart spring to mind ...
--
Terry
>
> AFN used only one or two AM frequencies actually, they had FM
> transmitters as well.
Three[1] (or, possibly, four) with high power transmitters easily
> AFN used only one or two AM frequencies actually, they had FM
> transmitters as well.
received in the UK in the 60s.
Plus, at closedown, a very long list of relay transmitters would be read
out, all with AM frequencies.
[1] Frankfurt, Munich and Stuttgart spring to mind ...
--
Terry
Paul Ratcliffe
Nov 28, 2011, 5:59:36 AM11/28/11
to
On Mon, 28 Nov 2011 09:16:03 +0000 (GMT), Jim Lesurf <no...@audiomisc.co.uk>
wrote:
>> Fascinating. And I'm jealous - I only ever went on Concorde once, and I
>> had to pay for it!
>
> I never went on a Concorde with normal seating and cabin service! :-)
I did, but sadly only in the hangar at Filton a couple of hours after
it touched down after the final flight anywhere in the world ever.
Got a picture with me and the Chief Pilot sitting in the driving seats
as well!
wrote:
>> Fascinating. And I'm jealous - I only ever went on Concorde once, and I
>> had to pay for it!
>
> I never went on a Concorde with normal seating and cabin service! :-)
it touched down after the final flight anywhere in the world ever.
Got a picture with me and the Chief Pilot sitting in the driving seats
as well!
André Coutanche
Nov 28, 2011, 6:19:12 AM11/28/11
to
Terry Casey wrote:
> Plus, at closedown, a very long list of relay transmitters would be
> read out, all with AM frequencies.
" ... Fulda and Wertheim on 1304, ..."
> Plus, at closedown, a very long list of relay transmitters would be
> read out, all with AM frequencies.
Shades of the Shipping Forecast ...
Lots of good stuff at http://northernstar.no/gamle_sider/afrs.htm .
André Coutanche
Bill Wright
Nov 28, 2011, 7:43:36 AM11/28/11
to
J. P. Gilliver (John) wrote:
> Certainly I (vaguely) remember (I was brought up in Germany in the
> 1960s/'70s) there being more FM-only sets (and hifis and so on) than
> here.
And many were exported to the UK.
> Certainly I (vaguely) remember (I was brought up in Germany in the
> 1960s/'70s) there being more FM-only sets (and hifis and so on) than
> here.
Bill
Bill Wright
Nov 28, 2011, 7:52:05 AM11/28/11
to
Bill
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