A pressure group campaigning for high-quality broadcasting has warned that 4G phone networks could knock out TV in one in ten UK homes - and by the time anyone notices it will be too late to fix.

The Voice of the Listener & Viewer, a membership and donation-funded lobbying body, wants guarantees that once next-gen mobile broadband is eventually rolled out, everyone will still be able to receive Freeview without having to spend money on special filters.

The group, otherwise known as VLV, had previously responded to Ofcom's consultation on the best way to stop 4G deployments at 800MHz from knocking out neighbouring telly transmissions. Not everyone agrees with VLV, however.

A couple of million households - roughly 10 per cent of the UK total - could receive degraded Freeview signals once the government gets around to flogging off an adjacent frequency band, left empty by the shift from analogue to digital television, to mobile operators.

The Ministry of Fun has allocated £180m from the 800MHz auction proceeds to pay for mitigation, but few of those responding to Ofcom's consultation on dispersing the cash seem to think that's enough and even fewer agree on the methodology.

Most interference can be addressed by putting a filter on the aerial wire; the problem is that the filter has to be on the aerial side of any installed booster. No one knows how many boosters are in use, but lots of them are in the loft beside the aerial which makes fitting more difficult than it might initially appear, especially if viewers aren't aware they even have a booster.

Ofcom, the communications regulator, hatched a plan to set up new company MitCo, which would send out filters with printed installation instructions. Anyone having problems could then ask for a fitter, with £20m ring fenced for the over-75s. If that didn't work then MitCo could install equipment to receive FreeSat or similar satellite services, which work on very different frequencies. But respondents to the consultation have been quick to point out the problems with this approach.

Multiple TVs means multiple headaches

The primary issue is that the majority of UK homes have more than one TV. Only 40 per cent are single-set houses, according to the Communications Consumer Panel, and that means a lot of people are going to have to shell out for their own filters. Freeview – the service jointly run by the BBC, ITV, Channel 4, BSkyB and transmitter biz Arqiva – reckons this isn't fair:

Consumers have bought into Freeview with enthusiasm and in good faith and through the process of switchover have made significant investment in Freeview equipment ... however, continuity of service is far from guaranteed. Many homes will be left with insufficient support to address interference problems and some will lose access to Freeview altogether.

Arqiva, which runs most of the UK's transmitter sites for cellular networks and broadcast TV, is equally damning of the proposals:

There is a real risk that either (a) filters will be incorrectly installed and therefore ineffective or (b) there is a significant consumer cost which could result in platform-switching behaviour. To avoid both of these real risks, Arqiva believes that MitCo should be accountable for the installation costs of filter in these cases.

Mobile operator Everything Everywhere has a slightly different take, pointing out that it could mitigate at the network level and thus significantly reduce the impact of 4G, but only if someone's gonna make it worth its while.

The existing proposal states that any surplus on the £180m gets split 50:50 between the 4G licence-holding network operators and the government, but that means, EE argues, that network mitigation, by reducing transmission power or repositioning phone masts, only makes sense where it can be done for less than half the cost of posting out more filters. That's also not allowing for the three-way split between then operators, so EE reckons it just won't happen.

Everything Everywhere does suggest it might find the cash for better transmission filters on the base stations, but to make that worthwhile the government will have to give up its 50 per cent share of any leftover money.

Meanwhile, rival operator Telefonica reckons the whole thing is a storm in a teacup created by commercial broadcasters trying to protect their revenue streams, and that we should just trust them not to cause undue interference.

"As DTT [digital terrestrial TV] users are also our customers, it is not in our interests to detract from their TV viewing experience," the operator explains, adding that "reputational and brand costs" will prevent it doing anything really awful. It accepts that MitCo may have to exist in some form.

The UK is quite unique in its devotion to broadcast television; most countries have a more diverse TV market, and have less to fear from 4G interference. Some respondents argue that by the time 4G coverage is extended into the rural areas where Freeview signals are weak, and where old people live, then the issue will disappear thanks to the magic of technology (such as better base-station filters).

The Voice of the Listener & Viewer is adamant that unless something is done then "well over two million homes ... may suddenly be facing blank screens". ®