Common Sources Of Rf Interference; Rf Sources - SABINE SW71-NDR User Manual

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 operat-
ing 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 comput-
ers, 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 broad-
casts, but also high enough to escape interference problems occurring at the
strong first harmonic of even the highest digital television broadcast. The band
is approved worldwide for a variety of uses, including such diverse transmit-
ters as baby monitors, garage door openers, wireless LANs, amateur satel-
lite, cordless telephones, etc. Compared to RF broadcast sources like televi-
sion and radio stations, these low power devices produce very localized, short
range interference; 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 func-
tion in the SWM7000 Remote Control Software. See Section 13.4.2.5 RF
Scan for a complete discussion of the benefits of scanning, which will reveal
any potential 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 70 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 SWM7000 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 prox-
imity within the same room as the wireless receiver (or reception an-
tenna). See caution below.
Commercial quality microwave ovens present a bigger potential prob-
lem. They sweep over a wider band of frequencies than the limited
band affected 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 70 different RF chan-
nels to choose from, makes serious interference problems arising from
microwave ovens avoidable and unlikely. See caution below.
Antenna Placement Caution
As a general precaution, keep 2.4 GHz cordless telephones, microwave ovens,
WLAN antennas and 2.4 GHz wireless video camera transmitters twice the distance
from your Sabine wireless microphone system antennas as that of your Sabine 2.4
GHz transmitters.
Tips & Troubleshooting
47
Sabine 2.4 GHz Smart Spectrum
®
Wireless
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