Ask A Scientist© Computer Science Archive

Index Key:   COM033
Author:      doug moe
Subject:     Computers and radio reception.
I was wondering what effect the newer type of computers, such as Pentium's
and so forth will have on radio's, since FM uses from 88 mhz to 108 mhz; and
these computers are running at 60 - 90 mhz.  It is certain that they will
get even faster, too.

Response #:  1 of 1
Author:      gregory r bradburn
Good question!  I would never have thought about it.  But you can be sure
that the designers of the computers have.  All telecommunications equipment
(as well as computers) fall under the scrutiny of the Federal Communications
Commission ((FCC).  Before a new product can be sold it has to be proven
that it will not interfere with normal radio/communications broadcasts (the
full band of communications).  You may find that if you place a receiver
very close to your Pentium you pick up a little additional noise -- I am not
sure what the exact FCC requirements are.  Remember that the 88 (to 108) MHz
specified for broadcast frequencies are the CARRIER frequencies.   Any
signal you pick up on your receiver would be at a frequency that is the
difference in your computer's clock rate and the carrier frequency.  Since
we are unable to hear sounds at frequencies more than (about) 20,000 Hz
there  would only be one (narrow) band on your radio where you would pick up
signal -- assuming your computer has a stable clock.  With TV the signal
bandwidth is nearly 5 MHz, but again you should only impact one station (if
at all).  The interference would probably show up as vertical, moving, lines
on your TV screen.
Let me re-iterate.  The FCC requires certification of new computer products
to avoid any major problems.  You SHOULD see no effect.