Freeview viewers in parts of west Wales will need to retune their TV equipment today (Wednesday) as local airwaves are cleared for the roll-out of faster mobile broadband.

Technical changes at the Preseli and Blaenplwyf transmitter groups will free up frequencies for the future introduction of fourth-generation mobile services.

Between now and the end of 2013, similar upgrades will be made at a number of transmitters across the UK to prepare for 4G.

TV services will be subject to disruption as channels including BBC One, ITV1, Channel 4, S4C, Channel 5, Film4, Yesterday and HD channels are moved to new frequencies.

Work at the main Preseli transmitter is expected to be completed by 6am and viewers receiving their TV from there can retune at any point after this.

Other local transmitters may be off-air until later in the afternoon. Once services resume, anyone missing channels should retune their TV or digital box to get them back.

Detailed advice on retuning is also available from Digital UK’s website (digitaluk.co.uk/retuning) and advice line on 08456 50 50 50.