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Third 4G interference test to start end of April - 28,000 households in parts of London to get free filter

4G filter ...picture credit: DMSL
Example of a 4G filter, available in various shapes and sizes
4G interference mitigation company at800 is to start a third test to investigate the extent to which 4G mobile services in the frequency band next to Freeview services will affect reception. In conjunction with the test, at800 will start its first major distribution of free filters in parts of London, ahead of a nationwide help scheme launching later in the year.

Approximately 28,000 households in Brentford and Isleworth will be sent a free at800 filter ahead of the test, which begins on 29 April. The at800 filter is designed to block 4G signals transmitted in the problematic 800 MHz frequency band, previously used for TV services and situated next to frequencies required by Freeview. Most people will be able to fit the filter themselves, though support is available for eligible viewers.

Reaction to the test and how many people require extra help will feed into at800's plans to help households across the UK when 4G in the 800 MHz band begins to be rolled out later this year. Simon Beresford-Wylie, chief executive of at800, said, "This test will help us assess any problems viewers may have with fitting filters and whether receiving one in advance improves awareness and understanding of the potential issue. We will have professional testing units and aerial installers in the area to help get Freeview services back to normal if they are affected by our test."

According to at800, the filter is "smaller than a pack of cards." It will not require a power source and is to be fitter between the existing aerial cable and TV or Freeview box. Where a booster or amplifier has been fitted, the filter will have to be connected between the TV aerial and the amplifier.

If viewers have difficulty fitting the filter, they should visit or call the at800 contact centre on 0333 31 31 800. For residents in buildings with a communal aerial system - where the antenna or aerial is not their responsibility - at800 will provide the building landlord or property manager with a free communal filter on request.

  • at800 has advised that if you’ve not been contacted directly through the post any interference to your Freeview service is unlikely to be due to the 4G test. TVs connected to a cable or satellite service are not affected.
  • The test in Brentford and Isleworth follows tests in South East London and the Black Country.


  1. i'm in london on the crystal palace transmitter
    should be interesting what 4G interference will
    do in my area, i'm also sharing a communal aerial


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