J G Miller wrote:

Depending on the municipality, the water in the US could have an awful
lot less chlorine (possibly none) than that supplied by one of the big
English water companies.

Not to mention that commie plot FLOURIDATION.

P O E! P O E! P O E!

:-) (does it really need one?)

Geoff.

--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(

On Monday, February 6th, 2012, at 16:19:04h +0000, Geoffrey S. Mendelson asked:

J G Miller wrote:

Carrying a PRI relay of BBC World Service is far cheaper than paying
for NPR programming, so many smaller public radio stations prefer this
option for obvious reasons.

Didn't the Bill and Melinda Gates Foundation help pay for it?

I could be wrong but I do not think that they specifically put any
money into BBC World Service on PRI affiliates. The partnership
between BBC World Service and PRI arose partly out of a joint news
program from Boston and WGBH "The World", and in response to
the BBC stopping their HF service to North America.

The Bill and Melinda Gates Foundation is active in funding a lot
of public radio and TV programming via the CPB for PBS programs
and directly with NPR, and with American Public Media (whose programs
are heard on both NPR affliates and PRI affliates).

On Monday, February 6th, 2012, at 11:50:27h -0500, Arny Krueger wrote:

Maybe you might want check out the meaning of the word consortium.

Yeah I was just plain wrong to say it was not a consortium --
I should have checked the "finer" details first.

In the case of PBS (television):

1) it is collectively owned by the affiliate stations

2) it produces no programs of its own, but these are supplied by
major stations (eg WETA, WGBH, WNET, KQED) for network viewing by
affliates who have paid the appropriate fee for the program

In the case of NPR (radio):

1) it is a corporation in its own right but stations pay to join as affiliates,
and each member station receives one vote at the annual NPR board meetings

2) NPR produces network programming to which individual stations
can subscribe

"J G Miller" wrote in message
...
On Monday, February 6th, 2012, at 11:50:27h -0500, Arny Krueger wrote:

Maybe you might want check out the meaning of the word consortium.

Yeah I was just plain wrong to say it was not a consortium --
I should have checked the "finer" details first.

In the case of PBS (television):

1) it is collectively owned by the affiliate stations

2) it produces no programs of its own, but these are supplied by
major stations (eg WETA, WGBH, WNET, KQED) for network viewing by
affliates who have paid the appropriate fee for the program

In the case of NPR (radio):

1) it is a corporation in its own right but stations pay to join as
affiliates,
and each member station receives one vote at the annual NPR board
meetings

2) NPR produces network programming to which individual stations
can subscribe

Agreement is a beautiful thing!

In message , David Looser
writes
Just on the offchance that you meant this seriously I'd ask just how many
people in the UK would actually want to watch French TV?
UHF only TV's could not receive it.
Many TVs sold in the UK had multiband tuners, and frequency converters were
easily obtainable. So of all the many factors that stopped the British
watching French TV that one was by far and away the easiest and cheapest to
solve.
Don't forget that French SECAM had positive going Video and (I think) AM
sound.
--
Clive

"Clive" wrote in message
news
In message , David Looser
writes
Just on the offchance that you meant this seriously I'd ask just how many
people in the UK would actually want to watch French TV?
UHF only TV's could not receive it.
Many TVs sold in the UK had multiband tuners, and frequency converters
were
easily obtainable. So of all the many factors that stopped the British
watching French TV that one was by far and away the easiest and cheapest
to
solve.

Don't forget that French SECAM had positive going Video and (I think) AM
sound.

True enough. But the original claim was that Britain failed re-use Bands 1 &
3 for TV as UHF only TVs couldn't receive French broadcasts. I was just
pointing that many UK TVs *could * receive VHF. You are quite correct that
French 625-line TV used +ve vision modulation and AM sound which would have
made receiving French TV on UK sets impossible even if we *had* used VHF for
625-line TV.

BTW AM sound was always used with +ve vision modulation. I'm not sure that
there was a killer reason why FM could not have been used with +ve vision
modulation, but intercarrier reception (the cheap'n'easy way to receive FM
sound with TV) wouldn't work with +ve vision modulation unless there was
significant carrier amplitude remaining at the sync tips. Normally with +ve
vision modulation the carrier amplitude at sync tips was nominally zero.

David.

BTW AM sound was always used with +ve vision modulation. I'm not sure
that
there was a killer reason why FM could not have been used with +ve vision
modulation, but intercarrier reception (the cheap'n'easy way to receive
FM
sound with TV) wouldn't work with +ve vision modulation unless there was
significant carrier amplitude remaining at the sync tips. Normally with
+ve
vision modulation the carrier amplitude at sync tips was nominally zero.

Early US TV sets used separate video and audio IFs -- intercarrier had not
been thought of at that point.

My understanding is that "inverted" polarity was used to minimize the
effects of noise bursts on the sync pulses.

In message , David Looser
writes
BTW AM sound was always used with +ve vision modulation. I'm not sure that
there was a killer reason why FM could not have been used with +ve vision
modulation, but intercarrier reception (the cheap'n'easy way to receive FM
sound with TV) wouldn't work with +ve vision modulation unless there was
significant carrier amplitude remaining at the sync tips. Normally with +ve
vision modulation the carrier amplitude at sync tips was nominally zero.
Many years ago I used to be in to TV and the thought at the time(often
expressed in "Television" magazine) was that the French were
deliberately different to keep manufacturing in France, hence the
positive luminance signal and AM sound. Another example of this was
what used to be called "Peritel" which was mandated for any TV sold in
France to keep out foreigners out. Who would have known at the time
that it would spread and be adopted as the now SCART socket
--
Clive

"William Sommerwerck" wrote in message
...
BTW AM sound was always used with +ve vision modulation. I'm not sure
that
there was a killer reason why FM could not have been used with +ve
vision
modulation, but intercarrier reception (the cheap'n'easy way to receive
FM
sound with TV) wouldn't work with +ve vision modulation unless there was
significant carrier amplitude remaining at the sync tips. Normally with
+ve
vision modulation the carrier amplitude at sync tips was nominally zero.

Early US TV sets used separate video and audio IFs -- intercarrier had not
been thought of at that point.

My understanding is that "inverted" polarity was used to minimize the
effects of noise bursts on the sync pulses.

That's a good part of it. The net purpose of inverted polarity was to
improve subjective dynamic range. White flecks on a grey background are far
less obvious than black ones.

In article ,
lid says...

On 2/6/12 1:16 PM, David Looser wrote:

The original plan, drawn up in the early '60s, was to re-engineer Bands 1
and 3 for 625-line operation once the 405-line service was switched off; but
it never happened. I guess that the powers that be thought that the spectrum
could be more usefully used for other purposes.

Of course it could, but harmonizing spectrum with the continent might
have been beneficial as well. Have these plans been published?


I don't see how we could harmonize system I channels with the French 919
line channels!

Other western European countries[1] used system B in a 7MHz channel
width and system G in an 8MHz channel at UHF.

To use the same channels we would have needed to devise a system X with
a truncated vestigial side-band to fit our 6MHz sound-vision spacing
into 7MHz - in reality, I don't think it would have fitted!

In practice, if we had decided to carry on using VHF for 625 line
broadcasting, I think we would have harmonised with the Irish 8MHz
channel plan - not least because of the proximity of NI transmitters to
those in the republic.

[1] Belgium also had its own variant of the French 819 line system
crammed into a standard 7MHz channel - it must have looked truly
appalling in comparison to 625!

--

Terry

"Arny Krueger" wrote in message
...

"William Sommerwerck" wrote in message
...
BTW AM sound was always used with +ve vision modulation. I'm not sure
that
there was a killer reason why FM could not have been used with +ve
vision
modulation, but intercarrier reception (the cheap'n'easy way to receive
FM
sound with TV) wouldn't work with +ve vision modulation unless there
was
significant carrier amplitude remaining at the sync tips. Normally with
+ve
vision modulation the carrier amplitude at sync tips was nominally
zero.

Early US TV sets used separate video and audio IFs -- intercarrier had
not
been thought of at that point.

My understanding is that "inverted" polarity was used to minimize the
effects of noise bursts on the sync pulses.

That's a good part of it. The net purpose of inverted polarity was to
improve subjective dynamic range. White flecks on a grey background are
far less obvious than black ones.
Umm..No. You've both got it the wrong way round. With -ve polarity sync
pulses are more affected by noise bursts than with +ve polarity. And white
flecks are far more obvious than black. Part of the reason is that impulse
interference could greatly exceed the 100% vision carrier level, saturating
the video amplifier and, with +ve modulation, the CRT.

This was why US TVs, where -ve modulation was used from the beginning,
employed flywheel sync very early on, whilst UK TVs didn't. On the other
hand UK TVs needed peak-white limiters to prevent the CRT defocusing on to
the "whiter-than-white" interference specs.

The real benefit of -ve modulation was AGC. With -ve modulation sync tips
correspond to 100% modulation and make an easy source for the AGC bias. With
+ve modulation sync tips are at zero carrier which obviously is useless for
AGC. Instead the back-porch has to be used and many different weird and
wonderful circuits were devised to "gate out" the signal voltage during the
back porch. Due to the need to keep costs down manufacturers increasingly
turned to "mean-level AGC" in which the video signal itself was simply
low-pass filtered to form the AGC bias. This lead to receiver gain being
varied by the video content, so the black on low-key scenes was boosted
whilst the whites in high-key scenes were reduced leading to a general
greyness to everything. To me it looked awful but as the Great British
Public kept buying these sets (and they were cheaper to build) mean-level
AGC became the norm for B&W UK domestic TV receivers. One great advantage of
colour was that mean-level AGC could not be used, to give correct colour
values colour sets *had* to display a picture with a stable black-level.

David.

David Looser wrote:

The real benefit of -ve modulation was AGC. With -ve modulation sync tips
correspond to 100% modulation and make an easy source for the AGC bias. With
+ve modulation sync tips are at zero carrier which obviously is useless for
AGC. Instead the back-porch has to be used and many different weird and
wonderful circuits were devised to "gate out" the signal voltage during the
back porch. Due to the need to keep costs down manufacturers increasingly
turned to "mean-level AGC" in which the video signal itself was simply
low-pass filtered to form the AGC bias. This lead to receiver gain being
varied by the video content, so the black on low-key scenes was boosted
whilst the whites in high-key scenes were reduced leading to a general
greyness to everything. To me it looked awful but as the Great British
Public kept buying these sets (and they were cheaper to build) mean-level
AGC became the norm for B&W UK domestic TV receivers. One great advantage of
colour was that mean-level AGC could not be used, to give correct colour
values colour sets *had* to display a picture with a stable black-level.

We have a PAL TV set that displays bright white as black. :-)

Geoff.

--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(

In message , David Looser
writes
"Arny Krueger" wrote in message
m...

"William Sommerwerck" wrote in message
...
BTW AM sound was always used with +ve vision modulation. I'm not sure
that
there was a killer reason why FM could not have been used with +ve
vision
modulation, but intercarrier reception (the cheap'n'easy way to receive
FM
sound with TV) wouldn't work with +ve vision modulation unless there
was
significant carrier amplitude remaining at the sync tips. Normally with
+ve
vision modulation the carrier amplitude at sync tips was nominally
zero.

Early US TV sets used separate video and audio IFs -- intercarrier had
not
been thought of at that point.

My understanding is that "inverted" polarity was used to minimize the
effects of noise bursts on the sync pulses.

That's a good part of it. The net purpose of inverted polarity was to
improve subjective dynamic range. White flecks on a grey background are
far less obvious than black ones.
Umm..No. You've both got it the wrong way round. With -ve polarity sync
pulses are more affected by noise bursts than with +ve polarity. And white
flecks are far more obvious than black. Part of the reason is that impulse
interference could greatly exceed the 100% vision carrier level, saturating
the video amplifier and, with +ve modulation, the CRT.

This was why US TVs, where -ve modulation was used from the beginning,
employed flywheel sync very early on, whilst UK TVs didn't. On the other
hand UK TVs needed peak-white limiters to prevent the CRT defocusing on to
the "whiter-than-white" interference specs.

The real benefit of -ve modulation was AGC. With -ve modulation sync tips
correspond to 100% modulation and make an easy source for the AGC bias. With
+ve modulation sync tips are at zero carrier which obviously is useless for
AGC. Instead the back-porch has to be used and many different weird and
wonderful circuits were devised to "gate out" the signal voltage during the
back porch. Due to the need to keep costs down manufacturers increasingly
turned to "mean-level AGC" in which the video signal itself was simply
low-pass filtered to form the AGC bias. This lead to receiver gain being
varied by the video content, so the black on low-key scenes was boosted
whilst the whites in high-key scenes were reduced leading to a general
greyness to everything. To me it looked awful but as the Great British
Public kept buying these sets (and they were cheaper to build) mean-level
AGC became the norm for B&W UK domestic TV receivers. One great advantage of
colour was that mean-level AGC could not be used, to give correct colour
values colour sets *had* to display a picture with a stable black-level.

Even with negative video modulation, it didn't seem to take the
Americans long to realise that they could cut costs by using AC coupling
in the video amplifier between the video detector and the CRT. [I've got
some old US monochrome TV circuits which definitely show AC coupling.]
As a result, the benefits of having an AGC line which didn't vary (much)
with video content would be essentially lost.

Regarding using the back porch as the signal reference, and deriving the
AGC from it, I recall a Wireless World article in around 1967,
describing a simple add-on circuit (which I made) which partly did this.
It worked both on 405 and 626-line signals. It wasn't intended to
improve the horrible mean-level AGC but, at the start of each video
line, it did clamp the video drive (to the cathode of the CRT) to the
black reference of the back porch. As a result, you still got the
contrast varying with video content (maybe not so much on 625), but at
least the black stayed (more-or-less) black.
--
Ian

In message ,
Terry Casey writes
In article ,
says...

On 2/6/12 1:16 PM, David Looser wrote:

The original plan, drawn up in the early '60s, was to re-engineer Bands 1
and 3 for 625-line operation once the 405-line service was switched
off; but
it never happened. I guess that the powers that be thought that the
spectrum
could be more usefully used for other purposes.

Of course it could, but harmonizing spectrum with the continent might
have been beneficial as well. Have these plans been published?


I don't see how we could harmonize system I channels with the French 919
line channels!

Other western European countries[1] used system B in a 7MHz channel
width and system G in an 8MHz channel at UHF.

To use the same channels we would have needed to devise a system X with
a truncated vestigial side-band to fit our 6MHz sound-vision spacing
into 7MHz - in reality, I don't think it would have fitted!

Of course, both the British and the Irish could have simply adopted the
European systems B and G (5.5MHz sound-vision - plus the horrendous
group delay pre-correction curve). If I remember correctly, the only
difference between systems B and G is the 7 vs 8 MHz channel spacing.
Even the VSBs are the same (0.75MHz).

In practice, if we had decided to carry on using VHF for 625 line
broadcasting, I think we would have harmonised with the Irish 8MHz
channel plan - not least because of the proximity of NI transmitters to
those in the republic.

Again, IIRC, the RoI VHF 625-line channels were the same frequencies as
the 'lettered' 625-line channels already used on many VHF cable TV
systems.

[1] Belgium also had its own variant of the French 819 line system
crammed into a standard 7MHz channel - it must have looked truly
appalling in comparison to 625!

I think that these had gone well before I got involved!
--
Ian

In message , Mike Tomlinson
writes:
In article , Arny Krueger
writes

http://hostedmedia.reimanpub.com/TFH.../FH01NOV_OUTLE
T_03.jpg

The ground wires in that picture appear to be in bare copper, borne out
by the person using a multimeter with a probe resting on the ground
wire. If so, that's pretty shoddy. What's to stop it coming into
contact with the exposed hot and neutral screws on the outlet body as
the outlet is pushed back into the box?

UK wiring regulations require earth (ground) wires to be sheathed in
green and yellow sleeving where it is exposed.

I have often been puzzled by this requirement. What is the reason - just
identification of the earth wire, or something else?
--
J. P. Gilliver. UMRA: 1960/1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf

Times are bad. Children no longer obey their parents, and everyone is writing a
book. -Marcus Tullius Cicero, statesman, orator and writer (106-43 BCE)

In message , Arny Krueger
writes:
[]
Oh good, we're going to argue about who can boil a kettle the fastest...
you couldn`t make it up!

No argument - the UK ring system seems to be vastly superior over our US 15
and 20 amp circuits when it comes to delivering more actual AC power to
appliances.


I think the voltage in use probably has about as much relevance as the
wiring system - at twice the voltage, the same power will require half
the current anyway. Doubling the wire as well obviously increases the
capacity too (or, allows the same capacity with thinner wire - though
I'm not as convinced by that argument as some).
--
J. P. Gilliver. UMRA: 1960/1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf

Times are bad. Children no longer obey their parents, and everyone is writing a
book. -Marcus Tullius Cicero, statesman, orator and writer (106-43 BCE)

In message , David Looser
writes:
[]
Well it might, but in practice there don't seem to have been many problems
caused by not harmonising spectrum use with the the continent. To be honest
I think the government made the right decision, the limited VHF spectrum
available in Bands 1 & 3 would only just have been enough for one extra
625-line TV channel.
[]
? - one on band I and at least one on band III, surely? I lived in
(West) Germany in the 1960s and '70s, and I'm sure we could get at least
two channels on band III (yes, I know B and G channels are narrower, but
not that much).
--
J. P. Gilliver. UMRA: 1960/1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf

Times are bad. Children no longer obey their parents, and everyone is writing a
book. -Marcus Tullius Cicero, statesman, orator and writer (106-43 BCE)

In article ,
Arny Krueger wrote:

The Hoover Dam in Nevada and the Grand Coulee dam in Washington state were
also built at about the same time. The Grand Coulee Dam provided massive
amounts of electric power to the Hanford plutonium refining facility.

Hanford consisted of running Uranium through carbon moderated water
cooled reactors, and then disolving the slugs in acid and chemically
seperating out the plutonium. (Buzzword: Purex). Not all that much
power demand, but tankloads of really radioactive crap that's still
there, 65 years later.

It was aluminum smelters. (The output of which got turned into heavy
bombers during WWII). There were, postwar, seven in Washington,
two in Oregon and one in western Montana, producing about a third of
the country's Aluminum. With the increasing population's power demand
soaking up the excess and raising power prices, and new competition
from Russia and Iceland, most, or all of them, have shut down now.

Eventually, in the last incarnation of the plutonium production facilites,
the N reactor, the cooling was used to generate electrical power.

(A new use for the power is Internet server farms. Microsoft has a big
one in Euphrata, near Grand Coulee, and Google has a one down in Oregon,
at The Dalles or Hood River).

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

In article ,
J. P. Gilliver (John) wrote:
UK wiring regulations require earth (ground) wires to be sheathed in
green and yellow sleeving where it is exposed.

I have often been puzzled by this requirement. What is the reason - just
identification of the earth wire, or something else?

It's just belt and braces - slightly less chance of a short if wires get
trapped by careless assembly.

--
*If horrific means to make horrible, does terrific mean to make terrible?

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

"J. P. Gilliver (John)" wrote in message
...
In message , David Looser
writes:
[]
Well it might, but in practice there don't seem to have been many problems
caused by not harmonising spectrum use with the the continent. To be
honest
I think the government made the right decision, the limited VHF spectrum
available in Bands 1 & 3 would only just have been enough for one extra
625-line TV channel.
[]
? - one on band I and at least one on band III, surely? I lived in (West)
Germany in the 1960s and '70s, and I'm sure we could get at least two
channels on band III (yes, I know B and G channels are narrower, but not
that much).
--

In the UK Band 1 was divided into 5 channels which, with care, could just
about support one national TV network. (a few low-power fill-in transmitters
for 405-line BBC1 had to operate in Band 3)

With 8MHz channels that would reduce to 3 which I suggest is not enough for
one national network.

Of course if you are only looking for local coverage you could run several
networks in the available spectrum. But the argument was that VHF gave
better national coverage than UHF. If that is the aim then, I suggest, you'd
need both Bands 1 and 3 to give truly national coverage of just one network.
Its probable that it would be possible to add a second network that only
covered the main population centres, as Analogue Channel 5 did on UHF.

David.

David Looser wrote:

Of course if you are only looking for local coverage you could run several
networks in the available spectrum. But the argument was that VHF gave
better national coverage than UHF. If that is the aim then, I suggest, you'd
need both Bands 1 and 3 to give truly national coverage of just one network.
Its probable that it would be possible to add a second network that only
covered the main population centres, as Analogue Channel 5 did on UHF.

I don't know how well UK sets worked in the 1960's, but US TV sets were
not capable of receiving adjcent channels at one time, so they were not
used. For example, channel 2 was used in New York City, while the nearest
channel 3 station was in Philadelphia, 90 miles away and too far to be
received without a large antenna.

I think the next one up was 5 in NYC and 6 in Philly.

When the US started UHF TV in the mid 1960's (all 1965 models had to
have VHF/UHF tuners), they spaced the channels far apart, Philadelphia
for example had three, 17,29 and 48.

Geoff.

--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(

In message , Geoffrey S.
Mendelson writes
David Looser wrote:

Of course if you are only looking for local coverage you could run several
networks in the available spectrum. But the argument was that VHF gave
better national coverage than UHF. If that is the aim then, I suggest, you'd
need both Bands 1 and 3 to give truly national coverage of just one network.
Its probable that it would be possible to add a second network that only
covered the main population centres, as Analogue Channel 5 did on UHF.

I don't know how well UK sets worked in the 1960's, but US TV sets were
not capable of receiving adjcent channels at one time, so they were not
used. For example, channel 2 was used in New York City, while the nearest
channel 3 station was in Philadelphia, 90 miles away and too far to be
received without a large antenna.

I think the next one up was 5 in NYC and 6 in Philly.

Generally, UK (and even European) TV sets had a hard time with adjacent
channels. Like the USA, the off-air broadcast channels were arranged so
that, within the normal service area, there would never be an adjacent
channel which was anything like as strong as the channel(s) intended for
that area.

The same was true of cable systems. As TV sets were incapable of
operating with adjacent channels, they carried only alternate channels.

However, things changed with the advent of cable set-top boxes. These
were specifically designed to be capable of receiving a level(ish)
spectrum of maybe 30+ channels. The tuned channel was converted to a
single output channel in Band 1 (selected to be a vacant off-air channel
in the area where the STB was to be used). Essentially, all the adjacent
channel filtering was done on output channel, so the TV set was
presented with only a single channel, thereby eliminating any problems
with poor adjacent channel selectivity.

Early STBs covered only non-off-air channels, eg 'midband' (between
Bands 2 and 3) and 'superband' (above Band 3 to around 300MHz). As a
result, large cable TV systems would carry alternate channels in Bands 1
and 3 (so that they could be received directly by the TV set), and
adjacent channels elsewhere (which could normally only be received via
the STB).

Later on, when multi-channel cable TV was recognised as 'the way to go'
by the TV set manufacturers, TV sets themselves started being equipped
with wideband tuners - typically providing virtually continuous coverage
from 50 to 300MHz and beyond, plus the UHF TV broadcast band. At the
same time, TV set adjacent channel selectivity was improved, as they had
to be capable of receiving the adjacent cable channels.

In the 1980s, SAW filters became widely available for use in domestic TV
sets, and these virtually eliminated the problems of interference from
adjacent channels. Of course, eventually, cable TV set-top boxes also
developed further, providing not only continuous wideband coverage of
from 50 to 870MHz, but they also became descramblers/decoders for pay-TV
services.

When the US started UHF TV in the mid 1960's (all 1965 models had to
have VHF/UHF tuners), they spaced the channels far apart, Philadelphia
for example had three, 17,29 and 48.

IIRC, at first, UHF was not very popular in the USA. Tuners were pretty
rudimentary - consisting of virtually nothing except a triode variable
frequency oscillator and a crystal diode mixer (techniques essentially
borrowed from WW2 radar technology), and this fed the input of the
existing VHF tuner. UHF transmitter powers were low, and as receiver
sensitivity was not much better than a crystal set, coverage was
minimal, so virtually no one bothered much with UHF TV. As a result, TV
sets continued to be manufactured fitted with only the traditional
12-channel lowband/highband VHF tuner.

Eventually, because of total congestion in the VHF TV bands, I believe
the FCC stepped in, and more or less forced TV manufactures to fit the
additional UHF tuner. I believe understand that they did this rather
indirectly - not by requiring TV manufacturers to fit UHF tuners per se,
but instead by making it illegal for them to ship TV sets across a state
border if they did not have a UHF tuner.
--
Ian

In article ,
says...

In message ,
Terry Casey writes
In article ,
says...


Other western European countries[1] used system B in a 7MHz channel
width and system G in an 8MHz channel at UHF.

To use the same channels we would have needed to devise a system X with
a truncated vestigial side-band to fit our 6MHz sound-vision spacing
into 7MHz - in reality, I don't think it would have fitted!

Of course, both the British and the Irish could have simply adopted the
European systems B and G (5.5MHz sound-vision - plus the horrendous
group delay pre-correction curve).

As the UHF bands had been engineered by international agreement for 8MHz
channels to accommodate all European 625 line systems (with the vision
frequency being common to all of them), it made sense to make better use
of the bandwidth available - in fact, as we were starting from scratch,
I've often wondered why we didn't adopt the eastern European OIRT
standard with its 6MHz vision bandwidth.

As for group delay, I suppose it made sense to pre-correct the
transmission to suit the average receiver group delay response. Were the
system I parameters, without group delay correction, determined in the
belief that UK manufacturers were so much better at designing IF strips
than their continental counterparts? ;-)

Group delay was something I never thought about - until a rude awakening
doing early experimental work on Teletext - but the introduction of SAW
filters resolved the problem ...

If I remember correctly, the only
difference between systems B and G is the 7 vs 8 MHz channel spacing.
Even the VSBs are the same (0.75MHz).


Yes, but don't forget the Belgian system H with 1.25MHz vsb ...

In practice, if we had decided to carry on using VHF for 625 line
broadcasting, I think we would have harmonised with the Irish 8MHz
channel plan - not least because of the proximity of NI transmitters to
those in the republic.

Again, IIRC, the RoI VHF 625-line channels were the same frequencies as
the 'lettered' 625-line channels already used on many VHF cable TV
systems.


Chicken and egg situation? RTE was broadcasting using VHF 625-line
channels at least two years before BBC2 came along. I think you meant:
many VHF cable TV systems used the 'lettered' 625-line channels already
used by RTE ...

Continental systems, of course, used the CCIR broadcast channels, as
well as filling up the gaps in between ...

--

Terry

In article ,
says...

In article ,
J. P. Gilliver (John) wrote:
UK wiring regulations require earth (ground) wires to be sheathed in
green and yellow sleeving where it is exposed.

I have often been puzzled by this requirement. What is the reason - just
identification of the earth wire, or something else?

It's just belt and braces - slightly less chance of a short if wires get
trapped by careless assembly.

It's also been changed twice!

Originally, earth wires were bare, then the requirement to cover them
with green sleeving was brought in.

Finally, the sleeving was changed from green to green/yellow ..

--

Terry

In article ,
says...

In message , David Looser
writes:
[]
Well it might, but in practice there don't seem to have been many problems
caused by not harmonising spectrum use with the the continent. To be honest
I think the government made the right decision, the limited VHF spectrum
available in Bands 1 & 3 would only just have been enough for one extra
625-line TV channel.
[]
? - one on band I and at least one on band III, surely? I lived in
(West) Germany in the 1960s and '70s, and I'm sure we could get at least
two channels on band III (yes, I know B and G channels are narrower, but
not that much).

Were both channels available nationwide or just in densely populated
areas?

Or is German topography more amenable to providing large area coverage
with fewer transmitters?

(I'm thinking here of the German plains that we were told for many years
provided ease of access for Soviet tanks ...)

--

Terry

In message , Ian Jackson
writes
IIRC, at first, UHF was not very popular in the USA. Tuners were pretty
rudimentary - consisting of virtually nothing except a triode variable
frequency oscillator and a crystal diode mixer (techniques essentially
borrowed from WW2 radar technology),
When I have a book about faults in American NTSC sets and was surprised
to see just how cut down they were. Instead of "I" subcarrier being
1.5MHz it was reduced in the sets to 1.0 MHz because that was the same
as the "Q" subcarrier and it made the sets cheaper to produce, with of
course the lower colour accuracy, but that came second to price.
--
Clive

In article ,
says...

In message , Geoffrey S.
Mendelson writes
David Looser wrote:

Of course if you are only looking for local coverage you could run several
networks in the available spectrum. But the argument was that VHF gave
better national coverage than UHF. If that is the aim then, I suggest, you'd
need both Bands 1 and 3 to give truly national coverage of just one network.
Its probable that it would be possible to add a second network that only
covered the main population centres, as Analogue Channel 5 did on UHF.

I don't know how well UK sets worked in the 1960's, but US TV sets were
not capable of receiving adjcent channels at one time, so they were not
used. For example, channel 2 was used in New York City, while the nearest
channel 3 station was in Philadelphia, 90 miles away and too far to be
received without a large antenna.

I think the next one up was 5 in NYC and 6 in Philly.

Generally, UK (and even European) TV sets had a hard time with adjacent
channels. Like the USA, the off-air broadcast channels were arranged so
that, within the normal service area, there would never be an adjacent
channel which was anything like as strong as the channel(s) intended for
that area.

The same was true of cable systems. As TV sets were incapable of
operating with adjacent channels, they carried only alternate channels.


SNIP

The UK UHF band plan specifically avoided the use of channels n, n + 5
and n + 9 in any transmitter group (n + 5 = n + IF; n + 9 = n + 2*IF) to
prevent interference.

I was quite surprised not to find any problems with a cable system I
started work on in 1969 which used 22 adjacent VHF channels (45 -
228MHz). As the system provided financial information only, there were
no sound carriers.

All the receivers used were modified domestic receivers using the ITT/KB
VC100 chassis. This chassis was effectively the old dual standard
chassis that had gone through at least five iterations that I can
remember - VC1, VC2, VC3, VC51, VC52 - in the previous four or five
years, with all the 405-line bits left out. Consequently it was really
quite an old design.

The GPO (which was just starting to transform itself into BT) were
responsible for the RF generation and trunk distribution and had chosen
a non-standard 8.3MHz channel spacing to ensure that the local
oscillator never clashed with a vision channel. This was possibly
inherited from the ILEA schools CCTV system they'd run because the
tuning errors they'd allowed for were a joke as our receiver tuning
always had to be spot-on because of the high frequency component of the
video - think CEEFAX in vision but with 48 character[1] lines.

Despite the adjacent channel traps in the receivers still being aligned
for 8MHz spacing(!) we never encountered any problems.

All later (broadcast) CATV and SMATV systems I've encountered, though,
have always used alternate channels, as described by Ian, for channels
intended for direct reception by a domestic receiver (i.e.: without
first being received by an STB).

[1] The worst characters in the special set used in these pre-decimal
days were 10 and 11 (for tenpence and elevenpence). Of these, ten was
the worst, producing a 10101 pixel sequence for most of its height -
tuning really had to be spot on for this!

--

Terry

On Wed, 08 Feb 2012 12:54:56 +0000, Terry Casey wrote:

Were both channels available nationwide or just in densely
populated areas?

Are you talking about channels or stations?

In the analog days of television in Bundesrepblik Germany, the three public networks
ARD Das Erste, ZDF, and die Dritten Fernsehprogramme (regional TV stations)
were available nationwide but as is the case in all countries (except Netherlands
and Vlaanderen), transmitter coverage was not 100%.

In the late 1980s, two commercial networks were allowed to start terrestrial
broadcasts -- RTL and Sat Eins, but these were low power and only available
in major urban markets.

With the switch off of analog TV, all TV transmissions in Germany are now
on UHF channels. In Western Europe, only Danmark and Letzebuerg have
transmitters with DVB-t on VHF Band III.

http://www.ukwtv.DE/sender-tabelle/

If you want to see which stations are available in the nation's capital
and surrounding region (Berlin-Brandenburg) then take a look at
the tables at

http://www.mabb.de/digitale-welt/dvb-t/programme.html

Note that in order to provide a good quality SD picture with rock solid
reception, the modulation is 16-QAM 8k FFT, and only four TV stations
per multiplex. Meanwhile SDN crams 12 video streams into 64-QAM 8k FFT
with reduced FEC because commercial dross trash and profits are more important
than picture quality and reception stability in a free-market light
touch regulatory broadcast framework.

In article ,
Terry Casey writes

Finally, the sleeving was changed from green to green/yellow ..

IIRC, it was to make it easier for colour-blind people to identify.

There's also been another change: the cores in T&E (=romex) used to be
red and black for phase and neutral, now it's been harmonised with
Europe to brown and blue.

Three-phase wiring has been harmonised from red, blue and yellow for the
phases and black neutral to brown, black, black and blue neutral. Yeah,
I know...

--
(\__/)
(='.'=)
(")_(")

"Mike Tomlinson" wrote in message
...
Three-phase wiring has been harmonised from red, blue and yellow for the
phases and black neutral to brown, black, black and blue neutral. Yeah,
I know...

You mean that two of the phases are the *same* colour? Surely not: how do
you know whether it's safe to connect two wires if they could be on
different phases? And if you connect brown, black and black to a three phase
motor and get the two blacks the wrong way round it will run backwards.

In message ,
Terry Casey writes
In article ,
says...

In message ,
Terry Casey writes
In article ,
says...


Other western European countries[1] used system B in a 7MHz channel
width and system G in an 8MHz channel at UHF.

To use the same channels we would have needed to devise a system X with
a truncated vestigial side-band to fit our 6MHz sound-vision spacing
into 7MHz - in reality, I don't think it would have fitted!

Of course, both the British and the Irish could have simply adopted the
European systems B and G (5.5MHz sound-vision - plus the horrendous
group delay pre-correction curve).

As the UHF bands had been engineered by international agreement for 8MHz
channels to accommodate all European 625 line systems (with the vision
frequency being common to all of them), it made sense to make better use
of the bandwidth available - in fact, as we were starting from scratch,
I've often wondered why we didn't adopt the eastern European OIRT
standard with its 6MHz vision bandwidth.

As for group delay, I suppose it made sense to pre-correct the
transmission to suit the average receiver group delay response. Were the
system I parameters, without group delay correction, determined in the
belief that UK manufacturers were so much better at designing IF strips
than their continental counterparts? ;-)

With System B , I think it's the closer proximity of the TV adjacent
sound traps that create the horrendous group delay curve. In System I,
they are 0.5MHz further away, and that seems to make all the difference.

Group delay was something I never thought about - until a rude awakening
doing early experimental work on Teletext - but the introduction of SAW
filters resolved the problem ...

So you've never had the ecstatic pleasure of tuning up the group delay
pre-distortion circuit in a System B/G modulator? ;o)))))

Of course, Norway realised the SAW filters for TV set IFs could be made
with a flat group delay response (rather than slavishly mimicking the
traditional L/C horrendous "-90, +140 microsecond" curve). For reasons
unknown to me, they decided to change the pre-distortion curve of their
transmitters to something like "flat to 4MHz, and -100us at 5MHz".
Heaven knows what your average Norwegian TV set made of this!


If I remember correctly, the only
difference between systems B and G is the 7 vs 8 MHz channel spacing.
Even the VSBs are the same (0.75MHz).


Yes, but don't forget the Belgian system H with 1.25MHz vsb ...

I've never actually come across it. Is it actually used? I guess it's
simply a relaxation of the unnecessarily-tight VSB roll-off of System G.
However, as the TV set IFs will all be B/G, they will hardly know the
difference.

In practice, if we had decided to carry on using VHF for 625 line
broadcasting, I think we would have harmonised with the Irish 8MHz
channel plan - not least because of the proximity of NI transmitters to
those in the republic.

Again, IIRC, the RoI VHF 625-line channels were the same frequencies as
the 'lettered' 625-line channels already used on many VHF cable TV
systems.


Chicken and egg situation? RTE was broadcasting using VHF 625-line
channels at least two years before BBC2 came along. I think you meant:
many VHF cable TV systems used the 'lettered' 625-line channels already
used by RTE ...

Ah! You could well be right. I only recently became aware that the Irish
launched their 625-line broadcasts in 1962, and of course, at the time,
the BBC were still only making experimental transmissions (albeit at
UHF). It's therefore unlikely that UK cable systems had any 625-line
programmes to put out until 1964 - and that would only have been BBC2.
It therefore makes sense that they adopted the Irish VHF TV frequency
plan, instead of vice versa!

Continental systems, of course, used the CCIR broadcast channels, as
well as filling up the gaps in between ...


--
Ian

In article , says...

On Wed, 08 Feb 2012 12:54:56 +0000, Terry Casey wrote:

Were both channels available nationwide or just in densely
populated areas?

Are you talking about channels or stations?

Stations (sorry - copied what the OP wrote ...)


In the analog days of television in Bundesrepblik Germany, the three public networks
ARD Das Erste, ZDF, and die Dritten Fernsehprogramme (regional TV stations)
were available nationwide but as is the case in all countries (except Netherlands
and Vlaanderen), transmitter coverage was not 100%.


The OP was referring to VHF transmissions in the 60s and 70s - are you
sure you are not wandering of into UHF territory here? That would make a
considerable difference to coverage ...

--

Terry

On 08/02/2012 14:18, Mortimer wrote:
"Mike Tomlinson" wrote in message
...
Three-phase wiring has been harmonised from red, blue and yellow for the
phases and black neutral to brown, black, black and blue neutral. Yeah,
I know...

You mean that two of the phases are the *same* colour? Surely not: how
do you know whether it's safe to connect two wires if they could be on
different phases? And if you connect brown, black and black to a three
phase motor and get the two blacks the wrong way round it will run
backwards.

It's brown, black. grey, blue. Still stupid and difficult for those with
colour blindness or working in low light.

Ron

"Mike Tomlinson" wrote in message
...
In article ,
Terry Casey writes

Finally, the sleeving was changed from green to green/yellow ..

IIRC, it was to make it easier for colour-blind people to identify.

There's also been another change: the cores in T&E (=romex) used to be
red and black for phase and neutral, now it's been harmonised with
Europe to brown and blue.

Three-phase wiring has been harmonised from red, blue and yellow for the
phases and black neutral to brown, black, black and blue neutral. Yeah,
I know...

BS7671 says that the colours are brown, black and grey, with blue for
neutral.

David.

In article , Mortimer
writes

You mean that two of the phases are the *same* colour?

Yes.

Surely not

Unbelievable but true. Foisted on us by the Eurocrats in Brussels.

: how do
you know whether it's safe to connect two wires if they could be on
different phases?

you don't

And if you connect brown, black and black to a three phase
motor and get the two blacks the wrong way round it will run backwards.

precisely.

I can see the benefit in changing from red+black to brown+blue in T&E as
those are the same colours used in flex, but to go from our previous
widely understood red/yellow/blue + black to the new scheme is less
convincing.

The idea, I think, was to continue the concept that the brown wire is
phase and blue neutral for consistency, but to use two black wires for
the second and third phases... words fail me.

See this:

http://jasper.org.uk/ingleses.jpg

this was an installation where a distribution board built in Britain was
shipped to a remote location in Europe. The Spanish electricians needed
a crib sheet to match up the colours correctly :-)

--
(\__/)
(='.'=)
(")_(")

In article , David Looser
writes

BS7671 says that the colours are brown, black and grey, with blue for
neutral.

Must have changed, then, 'cos I have seen several installations with
brown/black/black and blue. Also see the pic I posted earlier - look at
the Spanish names for the harmonised colours.

--
(\__/)
(='.'=)
(")_(")

"Mike Tomlinson" wrote in message
...
In article , David Looser
writes

BS7671 says that the colours are brown, black and grey, with blue for
neutral.

Must have changed, then, 'cos I have seen several installations with
brown/black/black and blue.

BS7671 permits the use of other colours as long as the ends of the wires are
clearly labelled "L1", "L2" etc. I guess the installers simply didn't have
any grey cable.

Also see the pic I posted earlier - look at
the Spanish names for the harmonised colours.

L1 is brown, yet your picture has "negro" against L1, so I'm not sure that
we can place any confidence in its veracity.

David.

In article , David Looser
writes

BS7671 permits the use of other colours as long as the ends of the wires are
clearly labelled "L1", "L2" etc. I guess the installers simply didn't have
any grey cable.

No, this is an armoured underground cable with cores in the colours
stated.

L1 is brown, yet your picture has "negro" against L1, so I'm not sure that
we can place any confidence in its veracity.

shrug I took the photo, and have seen the installation several times.
Here's another photo, since you seem to have trouble handling the truth:

http://jasper.org.uk/disboard.jpg

Let's not talk about the croc clips, shall we? :-)

--
(\__/)
(='.'=)
(")_(")

On Wednesday, February 8th, 2012, at 14:30:22 +0000, Ian Jackson wrote:

Yes, but don't forget the Belgian system H with 1.25MHz vsb ...

I've never actually come across it. Is it actually used?

Do you think there are still analog TV transmissions in Belgium, a
neighboring country whose capital is less distance (198 miles)
away from London than Edinburgh (332 miles)?

RTBF ceased the last analog TV transmissions on March 1st, 2010.

http://www.dvb.ORG/about_dvb/dvb_worldwide/belgium/index.xml

http://www.youtube.COM/watch?v=fY8rEjT7LeU

http://www.youtube.COM/watch?v=HoJYJUYtZGU

The VRT ceased analog TV transmissions on November 3rd, 2008.

Meanwhile analog TV transmissions continue in England and Northern Ireland ...

"Mike Tomlinson" wrote in message
...
In article , David Looser
writes

BS7671 permits the use of other colours as long as the ends of the wires
are
clearly labelled "L1", "L2" etc. I guess the installers simply didn't have
any grey cable.

No, this is an armoured underground cable with cores in the colours
stated.

Then it doesn't conform to EU harmonised colours.

L1 is brown, yet your picture has "negro" against L1, so I'm not sure that
we can place any confidence in its veracity.

shrug I took the photo, and have seen the installation several times.
Here's another photo, since you seem to have trouble handling the truth:

The "truth" is that the harmonised colours for three-phase are brown, black
and grey. If anyone is having problems handling the the truth then its you
I'm afraid. The photos only tell us about the one installation, who says it
conforms to the harmonised colours?

Its quite possible that the colours written-in are old pre-harmonisation
Spanish colours.

David.