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TETRA and television interference


Television is the bit of TETRA interference you are most likely to see, but in many ways it is the least worrying. Everyone in charge of this Airwave contract knew about TETRA and interference, not least from the commercial use of Dolphin TETRA at higher power levels over a period of years. So if you’re interested, to find out more about all the other safety-critical interference it causes, see our Will it work? page.

tetra interference from Woodside RoadIf you use terrestrial television the chances are that you will also experience TV interference, from mild ‘jazziness’ to a total loss of signal. This can be accompanied by complete loss of sound, replaced by loud, deep buzzing.

Depending on your area, your Channel 60 may get interference. In Worthing, ITV is therefore severely interfered (see picture). The effect is directly related to how high the TETRA transmitter is powered. When the antennae were added to an existing mast at Arundel station, West Sussex, Arundel Park Hotel lost all its television reception, on all channels, and had to pay out to restore their own service to their guests. Do you agree that O2 should pay instead? If you visit our Links page you can read up on the causes etc.

What does Ofcom think about this? Well, they seem not to grasp the seriousness at all. Compare this with our picture above:

TETRA interference

How can I recognise the interference?
‘The picture on the left shows the type of interference that can be caused to analogue TV reception, compared to a normal picture.’ (Source: Ofcom)

What can you do?

This is what O2 Airwave says:

‘I am sorry you have been experiencing television interference and understand this has been investigated by Ofcom. You will therefore have been made aware that the Airwave site at Worthing Football Club has been investigated and has been proved to be operating correctly and at the frequencies allocated to us by Ofcom. This indicates that the Airwave transmitter is not at fault. We cannot accept liability for something we are not legally liable for.

‘02 Airwave are obliged to comply with Ofcom regulations which state that resolving deficiencies within the viewer’s television installation is outside 02 Airwave’s responsibility and the RA’s statutory responsibility for regulating the radio spectrum.’

So there you have it we all have defective television installations! The same sentiment has been echoed by ministers in Parliament.

The remedy for our defective equipment is an £80 filter! One local supplier is estimating £220 to install. Ever wanted to be in the TV aerial filter business? Can’t think of a better time.

September 2005 update. Mast firm foots bill to cure TV reception. Airwave admits TV interference?! This is the second time Airwave has given in and restored viewing to communities that fought long enough. I hope their filters work better than mine.

  The Electromagnetic Compatibility Regulations 1992. What do you think a common-sense interpretation is?

Now read about TETRA: ‘How It Works’ from O2 Airwave, where it says:

‘The modulation method used is p/4-DQPSK (Differential Quaternary Phase Shift Keying). Though this linear modulation method is extremely spectrum-efficient, it requires very linear and therefore expensive transmitter final stages in order to minimise undesirable out-of-band transmissions.’

Quick survey

We called local aerial suppliers through the yellow pages three weeks after the Worthing masts had been switched on. The Littlehampton mast had been on for about eight weeks. 546 calls for filters had been received at an average cost of £58.

Shout! You must contact Ofcom (Tel. 020 8645 2200) and they will post you an interference report form. Unless everyone reports the interference, it officially remains an individual problem. Make sure they know the size of the problem.

Why complain? Maybe you’re on Cable TV, but many elderly or less well-off residents of the UK are not! Do it for them. Do it on principle. But do it.

TETRA, Worthing FC
TETRA, Worthing FC. Exceeds planning terms, erected without any consultation and affecting many surrounding residents’ health and well-being.

And now, below, with no further planning application, this mast is GSM, UMTS and TETRA. Three out of eight masts now at this site surrounded by dense housing.
TETRA, Worthing FC

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