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.

More likely they thought that getting the free TV from France was too
much competition.

UHF only TV's could not receive it.

Geoff.


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

"Geoffrey S. Mendelson" wrote in message
...
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.

More likely they thought that getting the free TV from France was too
much competition.

You forgot to add the smiley!

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.

David.

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.

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

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.

"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.

Geoffrey S. Mendelson wrote:
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.

More likely they thought that getting the free TV from France was too
much competition.

UHF only TV's could not receive it.

Geoff.


Do many people on the south coast actually bother with French
transmissions? I didn't see many south-facing aerials when I ventured
into that neck of the woods.

Bill

In article , Bill Wright
wrote:
Geoffrey S. Mendelson wrote:
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.

More likely they thought that getting the free TV from France was too
much competition.

UHF only TV's could not receive it.

Geoff.


Do many people on the south coast actually bother with French
transmissions? I didn't see many south-facing aerials when I ventured
into that neck of the woods.

they only "bothered" with them when they casued interference to UK
channels, although a firm in Parkstone, Dorset, used to sell suitable
aerials and SECAM receivers.

--
From KT24

Using a RISC OS computer running v5.16

In message , Bill Wright
writes
Geoffrey S. Mendelson wrote:
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.
More likely they thought that getting the free TV from France was
too
much competition. UHF only TV's could not receive it. Geoff.

Do many people on the south coast actually bother with French
transmissions? I didn't see many south-facing aerials when I ventured
into that neck of the woods.

I'm pretty sure that 'normal' UK sets could never really receive French
signals.

On 405-lines, we could certainly get the French positive mod 819-line,
14MHz wide signals - but these were displayed as two stretched, tall
images, side-by-side. And, of course, there was no sound, as the sound
(AM) was 11.15MHz HF or LF (depending on the channel number). Under
conditions of strong sporadic-E propagation, Band 1 French signals were
receivable in the UK at considerable distances and, in fringe areas,
could totally swamp the wanted signal.

On 625-line PAL, UK-standard sets can't really make anything at all of
the French positive mod, AM sound 625-line signals (SECAM if colour).
--
Ian