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