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ELECTROMAGNETIC INTERFERENCE (EMI) FROM RADIO WAVE SOURCES
Medical Power Wheelchairs (Hereinafter referred to as “Powerchair”) may be
susceptible to electromagnetic interference (EMI), which is a kind of interfering
electromagnetic energy (EM) emitted from sources such as radio stations, TV
stations, amateur radio (HAM) transmitters, two-way radio, and cellular phones. The
interference (from radio wave sources) can cause the Powerchair to release its brakes,
move by itself, or move in unintended directions. This can also permanently damage the
Powerchair’s control system.
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 taxis. These usually have the antenna mounted on
the outside of the vehicle.
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 problems to the Powerchair.
