The process of clearing the frequency currently used to deliver digital terrestrial TV (DTT) services will begin next month as the first stage of a major engineering programme gets under way.

The upcoming clearance follows the 2014 decision by Ofcom to approve European Commission plans to hand the 700MHz band to mobile phone operators, which are keen to use the spectrum for data services.

Ofcom initially wanted broadcasters to move to an alternative frequency by 2022 but in March stated that it wants the 700MHz band to be “nationally available for mobile data to a target of no later than Q2 2020”.

Digital UK, the not-for-profit organisation formed by broadcasters to assist consumers in the conversion to digital TV, the BBC, ITV, Channel 4 and Arqiva, which owns and operates the transmitter network, is co-ordinating the technical planning of the changes at TV transmitters across the UK, which will take place region by region.

According to Digital UK, around 90% of main transmitters will require some re-engineering for clearance, as will almost all of the 1,000 smaller relays in the network.

DTT platform Freeview said the updating of the Selkirk transmitter in south-east Scotland in March will enable the firm to test its processes ahead of the full rollout, which will begin in the summer.

The Selkirk transmitter serves about 18,000 homes. Some Freeview channels will move to new airwaves, which means that Freeview viewers in the south of Scotland will need to retune their TV equipment on 1 March to continue watching BBC channels.

Ofcom said that “for the vast majority, the move will require only a simple retune”.

It estimates that in total 100,000 households might need to change their roof-top aerial, and that a “small number” of viewers might need to fit a filter to their TV to prevent mobile phone signals from interfering with TV reception.

The regulator estimates the cost of the change to be £660m. But it has also priced the potential value of mobile operators using the spectrum in the region of £900m to £1.3bn, in part because signals transmitted in the 700MHz band reach further.

Senior broadcast figures have warned that the wider plans to move broadcasters from the 700MHz band will cause disruption to services and could mean broadcasters will have less frequency with which to launch new services.