EMI Warning
Electromagnetic Interface (EMI) From Radio Wave Sources
Powered motorized Powerchairs 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 a powered Powerchair to release its brakes, move by itself or move in
unintended directions. It also can permanently damage the powered
Powerchair's control system.
The sources of radiated EMI can be classified broadly into three types:
1.
Hand-held portable transceivers
(transmitters-receivers) with an antenna
mounted directly on the transmitting unit. Examples include: citizens band
(CB) radios, "walkie-talkies", 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 antenna towers) and amateur (HAM) radios.
**NOTE: So far as we know, other types of hand-held devices, such as
cordless phones, laptop computers, AM/FM radios, TV sets, CD players,
cassette players and small appliances, such as electric shavers and hair
dryers, are not likely to cause problems to your powered Powerchair.
Powered Powerchair Electromagnetic Interference (EMI)
Because EM energy rapidly becomes more intense as one moves closer to the
transmitting antenna (source), the EM fields from hand-held radio sources
(transceivers) are of special concern. It is possible, unintentionally, to bring high
levels of EM energy very close to the powered Powerchair's control system while
using these devices. This can affect powered Powerchair movement and braking.
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