Ofcom has outlined its plans for digital terrestrial television during and after the analogue switch-off.

In a statement, the regulator said that it was essential that steps be taken to ensure that BBC One, BBC Two, ITV1 and Channel 4 continue to reach the same number of households on digital as they do on analogue. Currently, those four channels reach 98.5% of households in the UK.

Capacity concerns were addressed in the Ofcom statement, with the regulator supporting the use of 64QAM mode by the three multiplexes broadcasting public service channels. 64QAM mode allows a greater number of channels to broadcast per multiplex at the expense of signal robustness; back in 2002, the ITV Digital-replacement service Freeview switched to 16QAM, which provides a more robust signal at the expense of capacity. To compensate for the less robust signal, more transmitters will be brought into operation and areas configured to be single frequency networks.

In these areas, potentially controversially, the 8k transmission mode will supplant the current 2k mode. This could affect viewers with DTT boxes and integrated DTT television sets that only support 2k mode. Ofcom has indicated that the Meridian and Anglia ITV regions will switch to 8k mode immediately after analogue switchoff, with the rest of the country following by the final switchover date of 2012. Ofcom did note, however, that 8k mode could be adopted earlier if "it can be shown to Ofcom’s satisfaction that the impact of an earlier adoption would have minimal impact on viewers with 2k equipment."