9
3 . E M I
This portion of the content will provide the user with basic information that describes the problems with
EMI, known sources of EMI, protective measures either to lessen the possibility or exposure or to
minimize the degree of exposure, and suggested action should unexpected or erratic movement occur.
Attention:
It is very important that you read this information regarding the possible effects of
electromagnetic interference on your
Mambo
power chair.
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ELECTROMAGNETIC INTERFERENCE (EMI) FROM RADIO WAVE
SOURCES
Powered power chair may be susceptible to electromagnetic interference (EMI), which is interfering
electromagnetic energy (EM) emitted from sources such as radio stations, TV stations, amateur radio
(HAM) transmitters, two-way radios, and cellular phones. The interference (from radio wave sources)
can cause the powered power chair to release its brakes, move by itself, or move in unintended
directions. It can also permanently damage the powered wheelchair’s control system. The intensity of
the interfering EM energy can be measured in volts per meter (V/m). Each powered power chair can
resist EMI up to a certain intensity. This is called its “immunity level”. The higher the immunity level,
the greater the protection. At this time, current technology is capable of achieving at least a 20 V/m
immunity level, which would provide useful protection from the more common sources of radiated EMI.
This powered power chair model as shipped, with no further modification, has an immunity level of 20
V/m without any accessories.
There are a number of sources of relatively intense electromagnetic fields in the everyday environment.
Some of these sources are obvious and easy to avoid. Others are not apparent and exposure is
unavoidable. However, we believe that by following the warning listed below, your risk to EMI will be
minimized.
The sources of radiated EMI can be broadly classified into three types:
1.
Hand-held portable transceivers ( transmitter-receivers with the antenna mounted directly on the
transmitting unit. Examples include: citizens band (CB) radios, “ talkie talkie”, security, fire, and
police transceivers, cellular telephones and other personal communication devices.
Attention:
Some cellular telephones and similar transmit signal while they are ON, even when not
being used.
2.
Medium-range mobile transceivers, such as those used in police cars, fire trucks, ambulances and
taxis. These usually have the antenna mounted on the outside of the power chair .
3.
Long-range transmitters and transceivers, such as commercial broadcast transmitter (radio and TV
broadcast antenna towers) and amateur (HAM) radios.
