South-east London test of 4G interference with TV

Shooters Hill Fire Station Mast from Eaglesfield Road

Shooters Hill Fire Station Mast from Eaglesfield Road

Will the new 4G mobile phone system interfere with our Freeview TV reception? We may find out next week when a test is being run in south-east London, including parts of Greenwich. A company called at800, a brand name for Digital Mobile Spectrum Limited (DMSL), is running the tests. Their press release said:

A test to help understand the extent to which 4G at 800 MHz may disrupt Freeview is being run in south east London. at800 is asking viewers in the area to report problems with television reception from Monday 15 April. at800 is the organisation tasked with ensuring viewers continue to receive Freeview when 4G mobile services at 800 MHz are launched later this year.

Approximately 170,000 household and business addresses in parts of Greenwich, Lewisham, Southwark and Tower Hamlets are being contacted directly to alert them to the test. This larger-scale testing follows an initial small-scale test in the West Midlands.

Households that at800 think will be affected will be sent a postcard like the one below in the next few days.

at800 specimen postcard

at800 specimen postcard

The new 4G mobile broadband will use the 800MHz frequency band that used to be used for analogue TV. This is close to the 700MHz that Freeview uses. An article by Barry Fox in April’s edition of Everyday Practical Electronics explained:

The 800MHz 4G band is very close to the 700MHz band frequencies used by Freeview. Co-channel interference is inevitable, especially for homes close to a 4G base station and where aerial amplifiers are used. Interference may well be variable and intermittent, making it harder to tie cause to effect.

It was estimated by Ofcom that that the problem could affect up to 2.3million homes, but in an initial pilot study covering 22,000 homes in the Midlands only 15 homes suffered interference.

If you suffer TV  interference next week, at800 have a number for you to call:

If you live in the south east London area and notice problems with your Freeview service from 15 April, please contact at800 by calling 0333 31 31 800. You will be asked for your postcode, the type of interference and the time it occurred. This will allow at800 to restore your service as soon as possible. Freeview is the television that viewers receive through their aerial.

Most cases of interference can be solved by fitting a filter between the TV and aerial, and at800 will provide one filter to each affected household. The at800 website has details of what needs to be done in different situations, and of the support that will be provided. In the worst case, where a filter doesn’t solve the problem then at800 will provide an alternative such as Freesat or cable at a cost of up to £10,000.

Cable and Satellite TV will not be affected by the 4G signal, only over the air, digital terrestrial television, to aerials.