Winradio G315, Руководство пользователя

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WiNRADiO G315 VHF/UHF Receiver
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Appendix C – 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, fax machines, 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 - and the video monitor in particular. Since the WiNRADiO
G315 receiver requires a personal computer to operate, this creates a
potential paradox. The WiNRADiO receiver itself is designed to be
substantially immune to PC 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 PC 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 worst culprits are usually video monitors, which radiate radio
frequencies at multiples of horizontal deflection frequencies. These
frequencies range from about 30 to 100 kHz, and you can sometimes hear
their harmonics right across the entire shortwave band. If you find strong
signals sounding somewhat like a tractor engine, spaced between
approximately 30 and 100 kHz apart (on modern hi-resolution monitors, the
typical frequency is around 94 kHz), your monitor is most likely the cause.