Detecting radio interference?

Am I right in thinking that various electrical appliances eg motors etc can cause some form of frequency clash with adsl? I believe 612kHz is the critical frequency? If so, is it simply a matter of tuning an AM radio to that frequency to try to trace the offending equipment?
If this is correct, I was wondering about trying a Roberts Sports 995 radio http://www.robertsradio.co.uk/Products/Analogue_radi... as it has a digital frequency display/tuner. Would this be a reasonable approach to trying to track down interference or any other recommendations?

Hi

Am I right in thinking that various electrical appliances eg motors etc can cause some form of frequency clash with adsl? I believe 612kHz is the critical frequency? If so, is it simply a matter of tuning an AM radio to that frequency to try to trace the offending equipment?

Yes and no.

Most if not all electrical equipment will cause interference on AM radio when a radio is held close to it, usually this interference will drop away a few metres from the device causing it. Even if noise is present this in most cases will not mean the equipment is causing any problems with ADSL. Just hold the AM radio near the ADSL router and see how much noise that is dishing out itself.

It can help identify very strong sources of interference, for example if you can walk for many metres and still hear the same interference it can then help you pin point where that may be coming from, and as it is wide spread it may be strong enough to cause ADSL problems, then again it may be having no affect at all.

What problems are you having?

A good way of trying to identify interference is to see a the SNR and bit allocation graphs from something like DMT if this is supported by your ADSL modem, preferably at a time the problem wasn't present compared to when it is.

Regards

Phil

Edited by deleted (Wed 16-Sep-09 22:14:51)

You might be better with a cheapo like this one from Amazon

Digitally tuned radios use discrete steps and have a narrow bandwidth. Something that tunes without steps and a poor quality (ie wider) bandpass may be easier to use.

John.

Motors give out random noise which will affect all frequencies, but the range that they radiate is quite small. You can tell a lot from how the noise varies in a 24 hour period. If the noise gets worse at night (SNR margin drops), then the likely cause is MW radio pickup by wiring (long wires act as aerials), but if the noise is fairly constant, then it could be noise radiated by a wired burglar alarm or a switched mode power brick. Any old cheap MW radio will pick up noise if held close to the phone wiring - I'd avoid one with digital tuning - this will not sweep the frequency spectrum, but will go up and down in steps.