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Although bidding opened last week for Britain’s fifth terrestrial TV
channel, the Independent Television Commission is losing confidence in the
technical feasibility of setting up Channel 5 with existing technology.
Many television engineers believe that the whole thing should be delayed
until digital broadcasting techniques are perfected towards the end of the
decade.

The problem with Channel 5 is that the spare frequencies on offer for
the service are used by many domestic video recorders, satellite receivers
and video games to transmit their signals through cables to TV sets. When
Channel 5 begins broadcasting in 1994, its transmissions will create interference
on the screen when these devices are in use.

As many as 10 million pieces of equipment could be at risk, each requiring
a visit by an engineer for retuning. The winner of the Channel 5 franchise
will have to pay the full cost of retuning.

The head of the ITC, George Russell, recently admitted that he had not
previously understood the extent of the technical problems facing any company
that takes on Channel 5. ‘Reading papers about the retuning problem is one
thing, seeing it for yourself is another. It startled me when I first saw
the effect it has.’

Russell stresses that getting the retuning right, and paying for it,
is now part of the quality threshold of the franchise. ‘If applicants don’t
pass it, there will be no licence award. We are quite ready to say no to
people who haven’t solved this problem.’

The ITC’s only concession is that the operator can phase in Channel
5 transmissions, serving at least 30 per cent of Britain by the end of
the first year of broadcasting but allowing a further five years to reach
the full 74 per cent that can be covered by the service’s 33 transmitters.
This would allow the operator to spread the cost of retuning over six years.

However, engineers believe that all plans for Channel 5 should be shelved,
to give the electronics industry time to perfect digital TV technology.
Instead of transmitting the TV signal as an analogue wave, the signal will
be converted into digital code, compressed and transmitted at much lower
power than an analogue signal. There is then much less risk of interference.

Brian Evans, a consultant on digital TV, believes the two Channel 5
frequencies could carry five digital TV channels instead of the one analogue
channel. He also estimates that gaps between existing TV channels could
carry another 20 digital TV channels.

Engineers at National Transcommunications Limited, formerly the Independent
Broadcasting Authority’s own research laboratory, are already working under
contract from the ITC to develop digital TV systems. At least one applicant
for the Channel 5 licence plans to offer a digital service. But few engineers
believe the technology for digital television can be ready at an affordable
price by 1994.

‘Digital TV is on the way,’ says Russell. ‘In five to ten years’ time
digital transmission on the Channel 5 wavelengths would avoid the need for
retuning altogether.