Interference from amateur and other hobby radio to domestic broadcast reception:investigation procedure

The Radiocommunications Agency (RA) is an executive agency of the Department of Trade and Industry, and is responsible for regulating the use of radio. We investigate complaints of interference to television or radio reception, if the interference appears to be caused by a radio or electromagnetic source. Interference happens when unwanted signals (which can come from many different sources) are picked up by a radio or television set or aerial, disturbing the reception.

RA often receives reports of interference allegedly caused by amateur radio and Citizens' Band (CB) installations, although we have found that most incidences of interference are not the fault of the amateur or CB enthusiast. We will only investigate a complaint if the information we receive shows us that the interference is likely to be caused by a radio or electromagnetic source. If you want RA to investigate an interference problem, please complete form RA 179, available on the RA website at www.radio.gov.uk or from the RA Library (telephone 020 7211 0502/0505).

New televisions and radios brought onto the market since 1 January 1996 must meet minimum standards of protection against interference, and they have a CE mark to show that they do so. However, we still receive many reports of interference where the problem is caused by lack of immunity in televisions and radios to unwanted signals. Even if the interference is only present when a nearby transmitter is being used, this does not necessarily mean that the transmitter is at fault – there may be nothing wrong with the transmitter or the way it is being operated.

Most interference problems concerning a radio amateur are quite easy to put right. Usually, amateurs are only too pleased to help a neighbour who has an interference problem; many cases of interference are resolved in a friendly way and are never reported to us. We do, however, investigate a small number of difficult complaints each year. These involve more in-depth investigation by our mobile teams – which are accredited by the United Kingdom Accreditation Service (UKAS) – using specialised equipment. They visit and take calibrated measurements to determine whether the amateur’s transmitter is generating an excessive received field strength at the affected equipment.

Measurement Technique

There is no specific standard for domestic radio/television installation. Whenever RA engineers are asked to judge whether a problem is caused by a radio/television receiver’s lack of immunity or by excessive emissions from a radio amateur or CB user, they use the laboratory standard for the immunity of a radio/television receiver. This standard requires the equipment to operate with "not more than a defined degree of degradation in a field strength of 125 dBuV/m (1.78 V/m) modulated 80%" (a radio measurement that can determine whether the transmitted signal level is unreasonable).

Measurements are made using a CISPR detector (a device with a known performance).

Our engineers usually take measurements from a point as close as possible to the boundary of the complainant’s property with the radio enthusiasts property. They make allowances for the reduction in signal strength due to walls or other obstructions.

We have produced a range of information leaflets on the use of the radio spectrum. These publications are all available on the RA website or can be obtained free of charge from:

Library and Information Service
Radiocommunications Agency
Wyndham House
189 Marsh Wall
London E14 9SX

Tel: 020 7211 0502/0505