How do I know if the 4G broadband will overload my Freeview TV?

Following tests conducted across the country, at800, the organisation responsible for protecting Freeview when 4G at 800 MHz is rolled out across the UK, has provided a new estimate of the likely scale of the impact.*  If national rollout reflects the results seen during its tests, at800 expects no more than 90,000 households, with Freeview as their primary TV service, to experience disruption caused by 4G at 800 MHz.**  Whatever the level of disruption, at800 is ready to restore Freeview to viewers.

at800 has now sent postcards to households in London and the surrounding areas in preparation for the activation of 4G at 800 MHz masts over the coming weeks and months. at800 is also sending postcards to other areas of the UK ahead of masts switching on.  at800’s mailing does not mean that 4G services will be available to consumers.  For information about the availability of 4G services, people should contact their mobile operators.

In London, in particular, Freeview received from the Crystal Palace transmitter is unlikely to be affected by mast activation because of the strong terrestrial television signal and its relatively large frequency separation from 4G at 800 MHz. However, at800 is sending postcards and running a publicity campaign to ensure anyone who does experience new disruption to their Freeview service knows how to get in touch.

More information for households receiving a postcard from at800 can be found here.

Only new 4G services at 800 MHz could cause problems with Freeview; existing 4G services from EE operate at 1800 MHz and do not disrupt television reception.

Download a PDF copy of this release – at800 updates estimate of likely impact of 4G at 800 MHz on Freeview

About at800

at800 is the consumer brand of Digital Mobile Spectrum Limited (DMSL), the organisation responsible for ensuring people continue to receive free-to-air television when 4G mobile services operating at 800 MHz are launched. The organisation is funded by the UK mobile operators with 800 MHz spectrum allocations to provide 4G services – EE, Telefónica UK (O2), Three and Vodafone.

Notes

*4G enables mobile devices such as smartphones, laptops and tablet PCs to access the internet at super-fast speeds and is expected to bring innovations in business, entertainment, education and public services. 4G mobile services at 800 MHz and digital TV operate in adjacent parts of the radio spectrum. Equipment that receives television signals, such as aerials, amplifiers and digital tuners, can fail to block 4G at 800 MHz. This can cause loss of sound, blocky images or loss of some or all Freeview channels. Freeview is the television that viewers receive through their aerial. BT Vision, YouView, TalkTalk and Top Up TV also provide Freeview services. Satellite and cable TV services are unlikely to be affected by 4G at 800 MHz.

at800 will contact those households it predicts may be affected by this issue before 4G at 800 MHz is switched on in their area. It will also contact businesses, social housing departments, care homes, hospitals, schools and colleges to advise what actions need to be taken.

** This figure also corresponds to less than 1% of households with Freeview as their primary TV service, according to the latest viewer figures from Freeview: http://www.freeview.co.uk/articles/about-us/press-releases/freeview-homes-surpass-11-million-as-bbc-two-hd-launches-on-freeviews-hd-service-today.html

During 2013, some of the frequencies that were used for television before the Digital Switchover will be auctioned off and used to provide 4th generation (4G) mobile broadband. Many homes will need to fit a filter, and a small few will have to switch (for free) to Freesat. Knowing in advance where these homes are is a complicated matter.

During 2013, some of the frequencies that were used for televis

 

The television digital switchover has been finished and 4th generation (4G) mobile broadband  also known as Long Term Evoluition LTE,  have launched all over the world, including a service from Everything Everywhere (EE) in the UK.

To understand why and how these 4G broadband services will cause problems during 2013, you need to take into consideration a number of technical factors.

Understanding the radio spectrum

The Radio spectrum is the name given to the frequencies of the electromagnetic spectrum that can be usefully used to transmit radio, television and data services.

The top bar on the diagram below  shows a selection of the services used in the UK, with old-fashioned long-wave radio, then medium-wave radio, though FM radio, the digital DAB radio services up to those used for television broadcasting.

Radio Spectrum for TV, radio, DAB and mobile phones

The highest frequencies on the diagram, the “ultra high frequencies” (or UHF) band is shown enlarged as the lower purple bar. In this range we can see TV “Channels 21-68(blue), second- and third- generation mobile phones ( orange, 3G pink) and the location for the 4G services.

It is important to note that some of the 2G capacity in the “1800MHz” range has already been converted to 4G operation by Everything Everywhere (EE). The other two yellow boxes show the 800 MHZ (to the left) “2.6GHz” (on the right).

For the purpose of Freeview  only the  800 MHZ range need be considered. The other two ranges will not cause Freeview problems.

Protecting Freeview receivers against overload

  Freeview boxes are designed to protect themselves against signal overloads. When they do this they close down and people often incorrectly diagnosethe problem as being no signal when there is too much.

The problem that has to be solved as the 4G services launch, is that the new mobile broadband signals can cause overloads onto the frequencies that are being used for Freeview.

Too much signal One particular problem is that a very common type of Freeview signal decoder, as Freeview  receivers are sensitive to signals being present nine channels (72MHz) away.

In addition to overloads, 4G may also cause Signal-inteference Noise Ratio degradation, where reception breaks down because the receiver can no longer decode the digital information in the transmission.

Knowing who will win the 4G auction

Too much signalUntil the  4G auction takes place, no one will know which company has the right to use the 800MHz channels for mobile devices. The following companies have qualified to bid:

  • Everything Everywhere Limited (UK)
  • HKT (UK) Company Limited (a subsidiary of PCCW Limited)
  • Hutchison 3G UK Limited
  • MLL Telecom Ltd
  • Niche Spectrum Ventures Limited (a subsidiary of BT Group plc)
  • Telefonica UK Limited
  • Vodafone Limited

Viewing high power television and using low power mobiles

Using the www.sitefinder.ofcom.org.uk link icon ‘Sitefinder’ Mobile Phone Base Station Database you can compare the locations of existing mobile phone “masts” with those used for  Freeview transmitters. Here is an example from Brighton and Hove, where a medium-sized single mast can cover a whole city, but where hundreds of mobile phone base-stations cover a many smaller-by-comparison areas.

Example of different coverage areas between 4G and Freeview

This illustrates two points. Firstly, that Freeview broadcasts are high powered and one-to-many – mobile devices are low power and peer-to-peer. The mast your TV signal comes from may be miles, sometimes tens or miles away, for your mobile perhaps only meters away.

The second point is that if an existing 2G/3G mobile supplier wins a 800MHz 4G slot, they will wish to use their existing “phone mast” locations (especially the 900MHz ones) as this would be most economical for them. Until the action winners emerge, and then plan their network only speculation about possible interference can be made.

Using the TV frequencies for 4G masts and phones

Research  shows that a 4G mast in relative close proximity, or a mobile 4G handset closer than a meter to an unfiltered Freeview box will cause overloading on many tested devices. The following diagram shows the relationship between the 4G use and the old TV channel designations.

Usage by 4G of old TV transmission channels

Those Transmitters that use channels above 52 are most likely to have receivers that get overloaded by the use of 4G signals in the 800MHz area. FDD is  

– Interpreting the aerial and mast locations

Once the proposed mast locations for 4G services are known, it will then be possible to predict which homes will need to fit the special filters in areas where Freeview uses the higher channel numbers (the C52 to C60 range).

The TV aerial on your rooftop, 4G mast, Freeview transmitter

If you then have a rooftop TV aerial without a signal amp to get an overload you will need the 4G mast to be in the line-of-sight between your Freeview transmitter and the aerial, or possibly “directly behind” the aerial.

If you then have a rooftop aerial and an amplifier, or perhaps have lower-grade cables, you are likely to need to protect from a 4G overload if the phone mast is close to your rooftop aerial.

Protecting Freeview boxes and sets, cables, amplifiers from 4G devices

Again in areas where Freeview uses the higher channel numbers (C52 and above) you may have to protect your Freeview devices from signals from a 4G handset (such as mobile phone, tablet, or USB “dongle”).

Your set-top box or Freeview TV, Your aerial cables, 4G mobile device

This may, once again, require the fitting of a special filter, or the upgrading of the “fly leads” used to connect your aerial to the set top box or TV. This may be a particular problem if you have used an indoor aerial or signal amplifier.