Threat to Freeview from 4G

Mobile Internet users will be pleased to know that from 2013, they may be able to enjoy mobile downloads with speeds of up to 100Mbps, using the new 4G mobile data services.

Faster mobile Internet comes as a price though, and recent reports show that three quarters of a million Freeview viewers might start to experience a loss of Freeview channels when the first 4G services start to roll out?

Why is this?

At the moment, analogue TV uses the UHF TV channels 21 to 68. Once the Digital Switchover is completed in 2012, a part of that band, UHF channels 61 to 68 (791 to 862 MHz), will be freed up. The Government will be auctioning that part of the band off to companies keen to cash in on the next generation of mobile broadband.

The risk

Here’s an extract from the OfCom report regarding possible interference from 4G:

“Existing DTT receivers and aerials were designed to receive signals across UHF Bands IV and V (470-862 MHz), including the whole of the 800 MHz band. This means that, in addition to receiving the wanted DTT signal, they may also pick up unwanted signals from new mobile base stations that could result in interference and degraded DTT reception”

The upshot, is that for those with TV aerials likely to pull in signals from the upper part of the analogue TV band, their Freeview receiver may get a bunch of unwanted interference from local 4G base stations. The unwanted signal, if powerful enough, will overload the tuner, resulting in a loss of service.

Those with masthead TV amplifiers may be the worst affected, and it will be hard for a filter to be applied to stop the unwanted, boosted noise from getting into the Freeview receiver. Particularly at risk will be those who get their Freeview signal via a communal TV aerial, as these systems typically employ an amplifier.

What’s the plan?

There are things that can be done to stop interference from 4G getting to your TV. The quickest and cheapest fix would be to use a bandpass filter, that only allows signals of between  477 to 790MHz to get through. A filter like this should cost around £10, and in many cases, will remove the unwanted signals when connected between the aerial and the Freeview receiver. It seems that the regulator Ofcom will be making sure that winning 4G bidders foot the bill for consumers looking to get filters to keep 4G out to anyone who’s hit by 4G interference.

It seems that an estimated 30,000 viewers won’t be able to use a filter to successfully screen out the interference though, and for them, satellite TV or Cable TV could be the only answer, and again, the bill for those viewers to switch to Sky or Virgin or cable may be handed to the 4G companies.

More details:

• For the OfCom report, and information about the consultation (which closes on 11 August 2011), visit the Stakeholders section of the OfCom Website