Carlon Structured Cable Management Systems Handbook - Low Res - Manual (Page 38)

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cellular phones, food processors, and rotary saws
each have their own noise signatures. Become
familiar with these and the culprit will be easier to
track down.
• Does the EMI happen continuously, at regular intervals
or at random? Answering this question helps you to
narrow down your search for the source of the EMI
to devices that match the time pattern of the noise.
• An easy way to check if you have identified the
source correctly is by turning the suspect piece of
equipment off and confirming that the EMI stops
and that the EMI starts again when the suspect goes
back on.
• Devices that are nearby are much more likely to have
an impact than those that are farther away. Conduct
your search for the source of the EMI starting from
the place where you have noticed the problem. Pay
special attention to powered devices that are physi-
cally close to the equipment that is experiencing the
problem or close to the cables leading up to that
equipment.
• If the EMI problem has developed over time, or has
occurred suddenly in a setup that had been perform-
ing acceptably in the past, look for what has
changed since the original installation. Has new
equipment been added? Have environmental condi-
tions, such as humidity or temperature, changed?
Has anything deteriorated as a result of weather or
sunlight exposure? Have animals gnawed through
the insulation somewhere?
EMI “VICTIMS”
The simpler the piece of equipment involved the less
likely it is to be disturbed by EMI. EMI can’t do much
to an electric clock, but a clock radio can be sensitive.
The higher the power of the input signal that a piece of
equipment uses, the less likely it is to be disturbed by
EMI. The same television will display less “snow” if it
is getting a strong signal from a set-top cable box than
a weak signal from a rabbit ear antenna.
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