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The
Labour government of Harold Wilson had made the decision that television should
be moved off from VHF and on to UHF. The benefits of UHF were many -
larger bandwidth available meant an increase in the line standard from 405 to
625; the UK allocation of spectrum was greater (the UK had asked for room for
only one VHF service in the 1930s, and had been granted two; it requested three
in the 1960s and was granted four) giving room for all three services (BBC-1 and
BBC Wales, BBC-2 and the ITA's broadcasts) on the same system with expansion
into either ITV2 (as the previous government had already announced in
Parliament) or BBC-3 (as the new government had hinted); the transmitters
belonging to the ITA and the BBC would be co-sited, so only one aerial would no
be required; and, of course, colour would be permitted on the new system.
UHF,
however, did have drawbacks. Firstly, people were to be asked not only to get a
new aerial only 15 years after investing in Band III reception, but now a new
set capable of 625-line reception. Secondly, from the point of view of the
engineers, a worse problem appeared - UHF signals simply did not travel as far
as VHF. Indeed, the results of UHF testing were very disappointing,
revealing that doubling the size of some masts would be required in order to
cover only half the previous population.
The
cautious ITA map above attempts to avoid telling the public what the ITA's
engineers already knew - that it may be years before UHF was available to many
of the people VHF already covered, and that some ITV contractors would suffer
huge losses of area.
This
fact is obscured in the map, but the simple facts can be seen by looking at (4)
Emley Moor. This transmitter's fringe reception under VHF reached from
Middlesbrough in the north to Leicester in the south and from Manchester in the
west all the way to the Lincolnshire coast in the east.
Under
UHF, the transmitter would barely cover the West Riding, while the UHF
transmitters assigned to Tyne Tees, (18) Bilsdale, would stretch almost to
Leeds, and the transmitter assigned to Anglia, (16) Belmont, would reach
practically to Sheffield.
This
was to present the ITA with a problem, as the new contractor in Leeds, Yorkshire
Television, could face becoming a large regional company, while Anglia could
suddenly (to the Norwich-based company's delight) replace YTV as one of the Big
Five.
This
problem would be put off for a while - the switch-off of VHF was not planned to
take place until the 1990s, while adoption of UHF colour sets by the public
might take until the mid-80s to become universal (in fact, switch-off was
achieved in 1985; there were no complaints, leading many to speculate that
everyone had, silently and without fanfare, gone out during the 70s and
purchased UHF and dual-standard sets, leaving nobody at all watching the VHF services by 1982. Colour licences overtook
monochrome in 1976-77, although the adoption of UHF colour, as compared to UHF
in black and white, is still not complete).
The
problems would be rectified at contract renewal in 1974; until them, the ITA
kept quiet about the impact UHF would have.
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