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Old 06-02-2012, 10:32 AM
kruser kruser is offline
Join Date: Nov 2007
Location: St. Louis County, MO
Posts: 2,499

Originally Posted by NC4DX View Post
Do you have DSL?
DSL does not normally cause or emit noise but it sure can be affected by noise in the MW band as that is where it operates. Noise in that band can totally wipe out a DSL signal.
Now the switching type power supply wall warts that come with almost everything these days are another story. Those things can be very noisy no matter what they are powering (DSL modems, routers, radios etc.).
The OP's breaker test should find that instantly though.

If you do find that a DSL signal is radiating from a phone wire, I'd first look at the phone wire and make sure it is at least Cat3 UTP or better and not the old untwisted pair stuff that most older homes were wired with. Still, the signal levels from a typical DSL modem are very low and should go unheard after moving any receiver antenna just a few feet away from the phone cable. The original DSL operated from around 60 kHz (or maybe it is 30 kHz) up to 1104 kHz so it definitely falls in the AM broadcast range. Then the newer DSL such as vdsl which Uverse uses, runs even higher in frequency. I have three DSL lines here all fed from a CO building that is far away so my modems all run at the maximum power level allowed and I've never had any noise worth mentioning radiate off the phone lines.
I'm sure if I placed a sensitive receivers antenna right alongside my phone cables that I would hear or see the noise floor rise though being a dsl signal is pretty widebanded!
I have tested my phone wiring and the DSL signal riding on it before. I went down to the ground floor and unplugged my lines from the NID so the signal was not making it up to my 3rd floor apartment but I never found any noise that bothered my receivers.
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