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930756 Rev. A
V. EMI (ELECTROMAGNETIC INTERFERENCE)
Heed all w
arnings to reduce the risk of unintended brake release or chair movement:
1. Beware of the danger from hand-held transceivers. Never turn on or use a
hand-held transceiver while power to your chair is on. Use extra care if you
belie
ve that such a device may be in use near your chair.
2. Be aware of nearby radio or TV stations, and avoid coming close to them.
3. If unintended movement occurs, turn your chair off as soon as it is safe to
do so.
A. WHAT IS EMI?
1. EMI means: electromagnetic (EM) interference (I). EMI comes from radio wave sources
su
ch as radio transmitters and transceivers. (A “transceiver” is a device that both
sends and receives radio wave signals).
2. There are a number of sources of intense EMI in your daily environment.
Some of these are obvious and easy to avoid. Others are not, and you may not be
able to avoid them.
3. Powered wheelchairs may be susceptible to electromagnetic interference (EMI) emit-
ted from sources such as radio stations, TV stations, amateur radio (HAM) transmit-
ters, two way radios, and cellular phones.
4. EMI can also be produced by conducted sources or electro-static discharge (ESD).
B. WHAT EFFECT CAN EMI HAVE?
1. EMI can cause your chair, without warning, to:
• Release its brakes
• Move by itself
• Move in unintended directions
If any of these occurs, it could result in severe injury to you or others.
2. EMI can damage the control system of your chair. This could create a safety hazard,
and lead to costly repairs.
C. SOURCES OF EMI
The sources of EMI fall into three broad types:
1. Hand-Held Transceivers:
The antenna is usually mounted directly on the unit. These include:
• Citizens band (CB) radios
• “Walkie-talkies”
• Security, fire and police radios
• Cellular phones
• Lap-top computers with phone or fax
• Other personal communication devices
NO
TE–
Th
ese d
evices can transmit signals while they are on, even if not in use.
2. Medium-Range Mobile Transceivers:
These include two-way radios used in police cars, fire trucks, ambulances and taxi cabs. The
antenna is usually mounted on the outside of the vehicle.
3. Long-Range Transceivers:
These include commercial radio and TV broadcast antenna towers and amateur (HAM) radios.
N
ote: Th
e following are not likely to cause EMI problems: Lap-top computers (without
ph
on
e or f
ax), Cor
dless ph
on
es, TV sets or AM/FM radios, CD or tape players.
V. EMI (Electromagnetic Interference)
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English