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3. EMI
This section provides the user with basic information that describes the problems with
electromagnetic interference (EMI), known sources of EMI, protective measures to either
lessen the possibility of 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
Attention
Some mobile telephones and similar transmit signal while they are ON, even
when not being used.
Electromagnetic Interference (EMI) from radio wave sources
Power chairs 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 mobile phones.
The interference (from radio wave sources) can cause the 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 power chair can resist EMI up
to 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 power chair model has an immunity level of 20 V/m
without any accessories.
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 guidelines listed below your risk to EMI will be minimized.
1. Hand-held portable transceivers (transmitter-receivers with the antenna mounted
directly on the transmitting unit. Examples include: citizens band (CB) radios, “walkie
communication devices.
2.
trucks, ambulances and taxis. These usually have the antenna mounted on
the outside of the power chair.
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