John Rumm wrote:

The quick solution to this is to stick in a freeview box - not affected
by these problems.

It's only unaffected up to the point at which it falls over completely
(digital cliff effect)! DTT can cope with co-channel analogue TV up to
about the same signal level as the wanted DTT signal (0 dB protection
ratio). It doesn't fare so well with co-channel digital interference
from another TX - which it sees as noise. The failure point there will
depend on the received C/N ratio without the CCI present and will
typically be 20 - 30 dB below the wanted signal.

The transmission spectrum planners aim to protect DTT against such
failure due to 'abnormal' propagation for at least 99% of the time
(averaged over a year or more) as opposed to the 95% of the time figure
used for analogue TV.

Of course with analogue you can see what's going on. CCI is easy to
recognise - but with digital you're unaware of the 'lift' until the
screen goes blank for no apparent reason...

--
Andy