Interference is any unwanted signal which
precludes reception of the best possible signal
from the source that you want to receive.
Interference may prevent reception altogether, may
cause only a temporary loss of the desired signal,
or may affect the quality of the sound or picture
produced by your equipment.Interference to home
electronic equipment is a frustrating problem;
but, fortunately, there are several ways to deal
with it.
- Colin's
Interference Handbook - Interference to
home electronic equipment is a frustrating
problem; but, fortunately, there are several
ways to deal with it. This handbook provides a
step-by-step process for eliminating the
interference
- Computer
EMI
- Dealing
with Computer generated RFI/EMI - One of
the most frustrating problems about using
computers with radios, whether it be for
controlling purposes or for decoding, is the
amount of RFI generated by these machines.
Most of the time, the RFI generated is enough
to render certain bands useless and on other
bands, it may drown out any weak signals and
distort or interfere with signals that you
want. The bad news is that, there is no way
that I know of to completely remove the
computer generated RFI in most situations. The
good news is that there are definite steps
that we can take to reduce the RFI to a very
acceptable level and in some cases, it will
almost disappear altogether. This document is
a compilation of suggestions from various
persons and some of the things I have tried
with my own system when dealing with this
problem. Many of the documents I have seen
relate to situations involving transmitters
and how not to generate them (RFI). This
document is written from a receiving point of
view.
- EMI
from RF-Driven Lamps
- General
Information about EMI/RFI
- How
to avoid radio interference to audio equipment
and telephone - written in Finnish
- QST
October 1992 Lab Notes on Telephone EMI -
amateur radio telephone interference
- Radio
Frequency Interference (RFI) Information Page
- Radio
Frequency Interference To/From Touch Lamps and
Dimmers
- The
ARRL Technical Information Service - lots
of documents on radio interference
- Using
ferrites for interference suppression -
One of the most used yet least understood
techniques for reducing both incoming and
outgoing RF interference is the application of
ferrite sleeves to cables and at interfaces.
This tutorial is meant to shed some light on
the use of ferrites, and also presents some
comparative frequency domain measurements both
to illustrate some of the points, and to give
designers an idea of what they might expect in
using and specifying a ferrite
component.
If you want that certain radio signal does
not get to a certain place you have generally
two options: shielding and jamming.There is no
device that can simply "block" an RF
transmission,other than by transmitting another
RF transmission on the samefrequency that is
overwhelmingly strong compared to the onebeing
"blocked". This is called
"jamming", and it is in generalillegal
worldwide, because intentionally interfering
with legitimate radiocommunications is illegal
in virtually all countries. There are a couple
of companies that manufacture cell phone
blockers, but the use of those is very much
limited to only few countries where use of them
is allowed. The only other option is to shield
the receiving device(s) from the transmission. A
grounded electrically sealed metal box will keep
the radio signal not from getting into it. In
some cases not completely shielded or wire mesh
box can attenuate the radio signals quite much
(the shielding effects of such not completely
closed structure depends very much on the signal
frequency).For instance, cell phones in a
theater could be rendered inoperative by making
the theater a completed closed conductive
chamber; i.e., asealed (electrically) metal box.
|
