WiNRADiO G65DDC User’s Guide
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Appendix D – Dealing with Interference
Electromagnetic Interference (EMI)
is what prevents us from receiving a
clear signal, even when the receiver should be sensitive enough to receive it.
There are many types of interference you can experience with radio receivers,
emanating from both natural and man-made sources.
Natural interference is produced by atmospheric phenomena such as storms
and sun activity.
Not so surprisingly, man-made interference is often worse. Sources include
electric motors, power lines, passing cars, electrical welding equipment,
fluorescent lights, domestic appliances, computer networks, etc. Receiving
antennas should always be as far away from sources of electromagnetic
interference as possible.
One significant source of man-made electromagnetic interference is the
personal computer. Since the
WiNRADiO Excalibur Sigma
receiver requires a
personal computer to operate, this creates a potential paradox. The receiver
itself is designed to be substantially immune to computer-generated
interference. However, any receiver needs to be connected to an antenna, and
antennas can’t discriminate between useful signals and interference. The
interference from your computer can either radiate directly to the antenna, or it
can be conducted to it along the outer conductor of the lead-in cable. Even in
professional radio receiving stations, a lot of care and effort is always needed,
if this type of self-interference is to be avoided.
Some computers are worse than others in terms of generated electromagnetic
interference. The specifics of a computer-based software-defined receiver
require a careful consideration with respect to computer-generated noise. Over
the past decade or so, computers have become considerably quieter in terms
of radiated radio frequency interference (RFI). Replacing CRT monitors with
modern LCD types has substantially contributed to this, as have strict FCC
and CE requirements with respect to allowable levels of RFI for consumer
products.
To check this, tune to some of the interfering signals, then switch off the
monitor and see if the signal disappears. If it does then you could continue
using the WiNRADiO receiver, and live with the fact that some useful
frequencies will be obscured by your monitor’s interference, or you can replace
