fcc_rf_electronics_regs

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From: g.haussmann@worldnet.att.net
Date: Tue, 6 Mar 2001 21:41:15 -0800
To: Ivan Passos <lists@cyclades.com>
Cc: svlug@svlug.org
Subject: Re: [svlug] 1U chassis entertainment & FCC

On Tue, Mar 06, 2001 at 06:03:16PM -0800, Ivan Passos wrote:
> Are you sure about that?? AFAIK, FCC Class-A is for home environments, and
> FCC Class-B is for work environments. And IIRC, Class-A is more
> restrictive / tough to pass than Class-B ...
> 
> Does anyone have more details on that, or can actually tell me whether
> this is right or not??


Class A is for commercial, industrial, or business environments, and class B is
for residential/home environments.  This applies to the US (FCC Part 15) and
Europe (the EMC directive, required for that 'CE' symbol on your computer's
label).  Other countries vary, but usually have something similar to the Class
A/B requirements.

Class B requirements are more stringent: a class B device must emit about 10dB
less (1/10 the power) of a Class A device.  Presumably this is since a business
is more willing and able to fix RF problems (moving equipment around, etc.).
Also note that the major consumer RF susceptible devices (that is, TV sets and
radios) are located in the home.

Supposedly you can drive around the valley with a spectrum analyzer and find
major server farms by their RF radiation alone, but I haven't actually tried
this myself...

In the interest of keeping this thread somewhat relevant to SVLUG, I should
point out that most SCSI and monitor cables are nasty RF radiators, which is
why most of these cables have a large ferrite suppresor on them.  Unterminated
ethernet cables on a LAN switch are also particularly nasty.  In fact, some of
the recent test equipment I ordered came with a clamp-on ferrite for the cable
you plug into the ethernet port.

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