What can cause interference to my television reception?

There are a large number of possible sources for television interference, but usually the problem is either linked to a nearby radio transmitter or more commonly that the television antenna and related devices (such as mast-head amplifiers, line splitters etc.) are of poor quality or old. Interference can also be caused by abnormal atmospheric and weather conditions; in cases such as this the interference will only last while the conditions persist.

Can anything else cause interference to my television reception?

Yes, some household appliances can produce what is referred to as ‘electrical noise’. This is usually caused by a device with a motor or thermostat, such as electric drills, can-openers and immersions. It is possible to find these items by noting whether the interference coincides with a particular appliance being in use.

Can I identify the source of the interference from the TV screen or sound?

Yes, this is possible and some examples of the more common types of interference are shown below, and a brief explanation given:

Interference

Example 1: The picture on the right is an example of good television reception. Note that the picture is clear and that no distortion is present
Example 2: This picture is an example of a weak signal, there is no interference to this signal and any distortion to the picture would indicate the reception installation is inadequate. Weak signals are more susceptible to interference due to abnormal atmospheric or weather conditions.
Example 3: This is an example of interference caused by the reception of two television signals at the same time. This can also appear as the picture from more than one program on the screen. Such cases of interference are common during periods of abnormal atmospheric conditions. In many cases it can be solved by modification to the reception installation.
Example 4: This picture shows an example of ‘ghosting’, where two pictures appear on the screen, usually out of synchronization. It is generally eliminated by modification of the reception antenna.
Example 5: The interference being caused in this image is being caused by an electrical device, usually devices with motors and devices with thermostats are sources of such interference.
Example 6: Radio transmitters often cause interference such as that depicted on the right. Such interference is usually intermittent and in very bad cases a radio operator’s voice may be heard over the television.

As mentioned above, it is sometimes possible that the interference can be heard on the television, the picture may or may not effected, and carries the content of the interfering signal. Try and distinguish what the interference sounds like, it is music or talk? If so can you identify the station? Can you hear radio operators? If so, can you identify any radio users in your area? Is it a buzzing or static sound? In theses case the interference is almost always related to an electrical appliance as mentioned earlier. These are all important in identifying possible sources of the problem.

Unfortunately in examples one, two and three, ComReg can do nothing to alleviate the interference being experienced as they are due to either a faulty or inadequate reception installation, or due to natural phenomena.

What should I do if I’m experiencing interference?

The first thing that should be done is to confirm whether to interference is being caused by an external source or if the problem is within you own system. In a lot of cases the problems are rectified by adjustments being made to the complainants own reception system. As such we would recommend that the complainant have their installation inspected by a reputable installer and have them pay particular attention to the mast-head amplifier, this is a small plastic box strapped to the pole just beneath the television antenna. A poor quality or faulty mast-head amplifier can be very susceptible to interference from external sources and can reduce picture quality.

In cases where the interference may be caused by an electrical device, which often appears on the screen as white dots or lines of white dots and is more often than not accompanied by a buzzing noise or ‘static’, the device responsible for the interference is in the complainants own home in many cases. Such devices can often be found by tuning an AM radio to a position where no radio station is received and bringing it around the area of the effected television. The buzzing noise will increase as the radio gets closer to the device which is causing the interference, by cutting the power to the device and noting whether the interference on the television disappears can confirm whether or not the device is causing the interference.

In cases where you believe that the interference is being caused by a radio transmitter, noting any conversations that may be audible, and taking note of nearby radio users can help in bringing about a resolution to the problem.

In all cases you should check with your neighbours and see if they are experiencing the same difficulties or is it unique to your reception, in cases where the problem is unique to your own reception it can be a good indicator that the problem is due to a fault within you reception system.

Will ComReg investigate my complaint?

Within ComReg it is the Spectrum Compliance Team that investigate matters of interference to the radio spectrum, and as such we endeavour to investigate all complaints of interference made to us. By following the advice above and being able to supply as much useful information as possible when making your complaint it may speed up the resolution time of such complaints. It should be noted that all complaints made to the Spectrum Compliance Team are prioritised and dealt with accordingly, complaints from emergency services and complaints involving safety of life issues always take priority and as such your complaint may not be dealt with immediately, although every effort will be made to deal with complaints in a timely manner.

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A note on mast-head amplifiers:

Mast-head amplifiers are generally used in the reception of signals over considerable distances, in Ireland most mast-head amplifiers are used for the reception of signals that do not originate in Ireland. The reception of Irish terrestrial stations should be possible without the use of such devices.

If you are going to use such a device you should ensure that it is of high quality and that it is screened and filtered. Amplifiers that are not screened or filtered are generally referred to as ‘wideband amplifiers’ and can cause problems for television reception by amplifying nearby signals that are not otherwise causing problems, in such cases the ‘interference’ is due to the amplifier and is not considered to be a case of external interference, the only remedy in most cases is either the use of a high quality mast-head amplifier, or not using the amplifier at all.

Poor quality and old amplifiers can cause problems for your, and you neighbours television reception by emitting radio signals, and in some cases can result in damage to television sets. Such devices can also cause interference to other services through such emissions.