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Radio Interference

What you can do about radio interference, TV interference, radio noise coming out of the music system, etc.

If you've got radio interference coming through, don't panic! There are various things you can do which might put a stop to it. Although radio signals are invisible and omnipresent and may seem to work in mysterious ways, science has the answers. So let's try and work out rationally what's going on.

The first thing to understand is that most radio interference is the result of faulty equipment and incompatibility, not the result of radio piracy or deliberate misuse. So if you've got a radio interference problem, try to avoid notions of it being "someone's fault" or thinking about someone being "to blame".

For example, if your new neighbour is a radio enthusiast and they've got scary abnormal aerials up, and since they moved in you've found to your dismay that you can hear them yackety-yacking through your music hi-fi centre and all kinds of strange alien beeping sounds, hold your peace! Strange as it may seem, even though it looks obvious it's the radio ham who's to blame, it could easily not be! Here is the correct procedure in such a situation:

1. Go along and visit the radio amateur and introduce yourself.
2. Explain politely that you can hear their transmissions through your domestic equipment.
3. The radio enthusiast now comes to visit you and inspects your hi-fi or whatever it is that's being played-up by the signals.
4. After a bit of technical debugging, during which you may be treated to hearing about all sorts of techie things which you probably won't understand, the character fits a special gizmo to your equipment, usually free of charge.
5. After that, no more interference.

This situation has happened many times, and there's no need to get irate about it. The problem is no-one's fault, but simply the poor quality of the interference rejection aspects of some domestic equipment. Situation solved, both electrically and diplomatically!

Another problem which has been observed, again with very little in terms of blame worth casting, is where one of your UK television channels (most commonly Channel 4) suddenly has diagonal lines across the picture, which weren't there before next-door put up a satellite dish. Chances are, it's a leaky piece of cable. This situation is explained in the page of good satellite cable to be used

Now we no longer have the Radiocommunications Agency to turn to for help, we may have to cope with some radio problems by helping each-other, with a few do-it-yourself methods. If you want to find a radio expert to call in for a consultation to try to help, you may find radio hams in your area are very helpful, knowledgeable, and have a deep interest in anything radio-related. Television repair shops may also be worth asking, but only if they are proper techno-enthusiast places (like proper computer shops). If you're really stuck you could ask Ofcom, but my own opinion is you'd be better off to drive around until you see a shack with a huge aerial on top and ask if the wizard within can help!

Another radio interference problem which can occur involves the sound of taxi drivers radios coming through your sound system. If this happens, listen carefully and try to find out which taxi company it is that's breaking through. Then look them up in the phone book and give them a call. The taxi company receptionist may be surprised to hear a phone call which starts with something other than "I'd like to book a taxi!", but when you explain (politely), that you can hear the taxi drivers over your sound system, you will almost certainly get a positive response. Taxi companies would prefer that you didn't hear them over the radio, and will generally look into the situation and take a responsible approach. They'll get a radio expert in, who will either point out that their radio is a cheap import and needs replacing with the proper gear, or they'll find the transmitter is ok and that it's your equipment that needs a gizmo adding as per the example of the neighbourly radio ham already mentioned on this page.

Another classic type of radio interference takes the form of a glitch which happens every so-many minutes. Most of the time there is clear reception, but then suddenly... splitch! A burst of radio noise, and then it's gone again. These were always a detective job to seek out, but one way or another they can be found and fixed. Thermostats are usually the problem, with their switch contacts eroded away causing a spark whenever they switch. Finding the source of the interference is made much easier if you gather the clues. To do this, get a notebook and a clock, and log the exact time of each glitch as accurately as possible. Do they occur at exact intervals? Do the observations correlate with temperature. Do the glitches occur only during the day or only the night or all of the time? Do they occur at weekends or only during business hours? All of these scientific clues will help to build up a picture of the interference source profile. Although this won't directly fix it, whoever you get to do the final homing-in on the interference source will be able to get to the bottom of it much quicker because of the data you have collected. It may seem like a lot of effort to pin down a tiny switch in someone's cupboard somewhere, but it's got to be done, or you'll just have to wait for the thing to have its little contacts fused together or to catch fire. Come to think of it, perhaps you'd better do an experiment by turning off your own electric water heater just to make sure it's not your own thermostat that's the problem!


I hope some of this info I have provided is some help to you, and if you've got radio interference I hope you get it cleared up. Please understand, though, that I am not the Radiocommunications Agency and I am not Ofcom and I can't sort out everyone's radio interference problems. But at least this page is a good start and the helpful hints may go some way to resolving the problem.

Also see PLT QRM at www.mds975.co.uk/Content/amateur_radio_BPL_interference.html ... yet another of Ofcom's failures.