I worked on RFI and EMC problems associated with DSL, both CAP/RADSL and
DMT. The telco portion has mandatory immunity testing (under Telcordia
GR-1089 and telco addenda to that) so is pretty good. But the downstream,
Customer Provided Equipment (CPE) end, where signals may be only
microvolts, these have no immunity requirement. Conducted noise at
residential installations may be in the millivolts -- or even volts -- so
it's easy to see the problem.
I've seen a specification for *one* vendor's modem that required emissions
20 dB below Part 15, a good figure, I think. But immunity, especially to RF
noise in the power, was a particular problem in one modem I worked with. I
solved it, though I don't believe they changed the design -- and then we
changed from CAP/RADSL to DMT in the next iteration.
Cortland
> From: Richard Zalewski <w7zr@citlink.net>
> Subject: Re: [RFI] Speedstream WiFi network
>
> May not be 100% on topic but I have a SpeedStream DSL external modem that
> has LOTS of problems with HF RF and even low levels. AND the company has
> not interest in advising or fixing the problem.
>
> Dick W7ZR
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