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CAUTION
IT IS VERY IMPORTANT THAT YOU READ THIS INFORMATION REGARDING THE POSSIBLE EF-
FECTS OF ELECTROMAGNETIC INTERFERENCE ON YOUR POWERED WHEELCHAIR.
Electromagnetic Interference (EMI) From Radio wave sources
Powered wheelchairs and motorized scooters (in this text, both will he referred to as powered wheel-
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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 cellular phones. The interference (from radio wave sources) can cause the powered
wheelchair 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 mea-
sured in volts per meter (V/m). Each powered wheelchair 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 wheelchair model as shipped, with no fur-
ther modification, has an immunity level of 20 V/m.
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 unavoid-
able. However, we believe that by following the warnings 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 (transmitters-receivers) with the antenna mounted directly on the
transmitting unit. Examples include: citizens band (CB) radios, "walkie talkie," security, fire, and police
transceivers, cellular telephones, and other personal communication devices. NOTE: some cellular
telephones and similar devices transmit signals 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 tax-
is. These usually have the antenna mounted on the outside of the vehicle; and
3) Long-range transmitters and transceivers, such as commercial broadcast transmitters (radio and TV
broadcast antenna towers) and amateur (HAM) radios.
NOTE: Other types of hand-held devices, such as cordless phones, laptop computers, AM/FM radios, TV
sets, CD players, and cassette players, and small appliances, such as electric shavers and hair dryers, so
far as we know, are not likely to cause EMI problems to your powered wheelchair.
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