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ELECTROMAGNETIC INTERFERENCE
CAUTION: IT IS VERY IMPORTANT THAT YOU READ THIS INFORMATION REGARDING
THE POSSIBLE EFFECTS OF ELECTROMAGNETIC INTERFERENCE ON YOUR POW-
ERED WHEELCHAIR.
Electromagnetic Interference (EMI) From Radio Wave Sources
Powered wheelchairs and motorized scooters (in this text, both will be referred to as powered wheelchairs)
may be susceptible to electromagnetic interference (EMI), which is interfering to 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 measured in volts
per meter (v/m). Each powered wheelchair can resist EMI up to a certain intensity. This is called its "im-
munity 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.
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 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," sec-
urity, 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 while 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 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.
EFFECTIVE DECEMBER 2, 1994 THE FEDERAL GOVERNMENT REQUIRES THIS STATEMENT TO BE INCLUDED.
