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Sabine Smart Spectrum
®
Wireless
LIT-SWM6-7000-OG-EN-110203.indd
© 2011 Sabine
, Inc.
14.3. Common Sources of RF Interference
The typical sources of interference for conventional wireless mics can be high-
powered broadcasters such as radio stations and TV transmitters, or other short-
range wireless devices, including multiple radio microphones operating at the
same location (either by design, or by coincidence), that operate in proximate
(or harmonically related) bands. Less commonly, interference may arise from
spurious outputs emitted by electronic equipment (notably computers, printers,
or similar devices with digital clocks), faulty electrical equipment, neon signs,
dimmers and lighting controllers, and so forth.
Many UHF and VHF mics are especially vulnerable because they share the RF
spectrum with the very high-powered transmitters for television. The coming
conversion to digital and high-definition broadcast will increase the problems
for UHF and VHF.
The 2.4 to 2.4835 GHz frequency band is not only well above the fundamental
(nominal) transmission frequencies of such strong analog and digital broadcasts,
but also high enough to escape interference problems occurring at the strong
first harmonic of even the highest digital television broadcast. The band is ap-
proved worldwide for a variety of uses, including such diverse transmitters as
baby monitors, garage door openers, wireless LANs, amateur satellite, cordless
telephones, etc. Compared to RF broadcast sources like television and radio
stations, these low power devices produce very localized, short range interfer-
ence; furthermore, many of the devices working in the 2.4 GHz range use spread
spectrum transmission and reception. Both of these facts mean such uses of the
RF spectrum are less likely to cause interference with, or suffer from interference
from the use of, Sabine’s systems.
14.3.1 RF Sources
Your first step in checking for interference should be utilizing the Scan function
in the SWM Remote Control Software. See
Section 13.4.2.5 RF Scan
for a
complete discussion of the benefits of scanning, which will reveal any poten-
tial RF sources in your location and allow you to make an informed choice of
channels to use. The scanner can scan for long periods of time and will give
you a report of RF activity over time for each of the channels available on your
Smart Spectrum system.
1. Microwave ovens
In the vast majority of situations, interference from microwave ovens will
not affect performance of your SWM series microphone systems. Since
barriers such as walls work to block interference, a microwave oven will
likely present a problem only when located in fairly close proximity within
the same room as the wireless receiver (or reception antenna). See cau-
tion below.
Commercial quality microwave ovens present a bigger potential problem.
They sweep over a wider band of frequencies than the limited band af-
fected by consumer units, and use two magnetron tubes which alternate
to avoid inactivity during a power cycle. Fortunately, Sabine systems
are only affected by such ovens in close proximity to receiver antennas.
That protection, plus the availability of multiple RF channels to choose
from, makes serious interference problems arising from microwave ovens
avoidable and unlikely. See caution below.
Tips & Troubleshooting
As a general precaution, keep 2.4 GHz and 915 MHz cordless telephones, microwave
ovens, WLAN antennas and wireless video camera transmitters twice the distance
from your Sabine wireless microphone system antennas as that of your Sabine
transmitters.
Antenna Placement Caution
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