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LTE/4G and TV interference – A summary

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 The end of analogue TV and the completed switch to digital has freed frequency spectrum that can be used for other services now that TV services make more economical use of what was purely TV transmission bandwidth.  Our broadcast TV can be fitted in less space which has made room for ‘Fourth Generation’ (4G) mobile services related to fast, mobile broadband. During 2013 the government auctioned the available space to mobile operators.

4G will involve much higher power base stations and mobile devices.  The mobile device could be a smart phone, tablet or a plug-in dongle.  The first roll-out is planned to cover Britain’s major conurbation areas so there is not likely to be rural benefit in early stages.

Transmissions started in July 2013, however one company, Everything Everywhere (EE, who own Orange and T – Mobile) already operate 4G services and this has caused confusion with the public.  EE have been granted the use of old 2G frequencies around 1800 MHz for a version of 4G.  This will not cause problems with terrestrial digital television but, due to the higher powers being used, may create issues with certain satellite programmes, especially if systems are not installed to CAI standards.

The base station signals required for the new services have the potential to interfere with some existing TV reception.  TV aerials were traditionally manufactured just to cover a certain part of the TV spectrum related to local transmitters.  However to enable a smooth switchover most of the aerials installed in recent times cover the whole of the spectrum and therefore capable of receiving LTE, giving rise to potential interference. The CAI has introduced a new aerial benchmark that certifies aerials designed to operate over less bandwidth therefore minimising LTE ingress. The following link will detail the new standards.

http://www.cai.org.uk/information/benchmarking-scheme/benchmarking-scheme

Ofcom believes that the fitting a filter will solve many of the problems and a company, Digital Mobile Services Limited – publicly known as ‘at800’, has been set up by the mobile phone operators to deal with these issues. Initially supply a simple in-line filter to the consumer if they complain of interference or pre-empt the problem if tests in an area show interference could occur.  Many householders will be able to fit the filter themselves, however this filter will need to be fitted in front of any amplification and if necessary, may need to be installed by a professional engineer (the cost of doing this will being covered by a voucher redemption scheme).  Where a filter does not solve the issue then funding will extend to paying for aerial upgrading or a change of platform (e,g. satellite or cable delivery).  There is also a fund to assist the aged and vulnerable. The scheme only deals with problems on the main TV in the property with any further sets being the responsibility of the householder.

Where a communal signal distribution system is in place such as in blocks of flats or commercial buildings the problems could be more complex requiring trained, competent engineers. In these cases the owner of the system will have to cure the problem at their own expense where work goes beyond the provision of a free filter.