If you read the OFCOM consultation document on digital swithcover, there are five possible scenarios relating to coverage.
All scenarios assume that all 1184 transmitters will be switched to digital. About 200 main transmitters would transmit 6 multiplexes, the remainder would only transmit 3 (Mxs 1, 2 and B)
1. Transmit all channels at 16 QAM giving good quality signal, but reduced coverage. Some transmitters would get a power increase. This option will IMPROVE coverage over analogue, but would reduce channels available on Mx 2.
2. Transmit Mx 1 and B at 16 QAM and Mx 2 and 64 QAM giving reduced coverage for Mx 2 (but increased number of channels). Mx 2 would operate at a higher power than 1 and B to compensate for the reduced coverage of 64 QAM transmission. A few extra transmitters would be built to maintain coverage equivalent to analogue (though some viewers might lose Mx 2).
3. Transmit all Mxs at 64 QAM at higher power rate with new transmitters as in 2. This means more channels on Mx 1 and B to present, but some viewers on the fringes of reception would receive no DTT.
4. As in option 2, but with no new transmitters built. This would result in 100,000 homes losing terrestrial television (and no doubt these homes are not in areas covered by cable).
5. As in option 2 but no increased power for Mx 2 and no new trasmitters. This results in 350,000 homes losing terrestrail TV.
I feel very strongly that as many people as possible should submit responses to OFCOMs consultation. I for one am in a position where I need option 1, and no others. I receive poor DTT at present, so I need to power boost due at my transmitter (Mendip). Cable is not available to me and I cannot have a satellite dish at my home.
For the full text of the consultation document see:
http://www.ofcom.org.uk/consult/condocs/pods/pods.pdf