Sources Of Emi - Quickie QM-7 Series Service Manual

Sources of EMI

1. Hand-Held Transceivers: Antenna is usually mounted directly on the unit.
These include:
•
Citizens band (CB) radios
•
"Walkie-talkies"
• Security, fi re and police radios
• Cellular phones
•
Lap top computers with phone or fax
•
Other personal communication devices
Note - These devices can transmit signals while they are on, even if not in use.
The wheelchair should be switched off when not in use.
2. Medium-Range Mobile Transceivers: include two-way radios used in police
cars, fi re engines, 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, amateur (HAM) radios, and alarm systems.
NOTE- The following are Not likely to cause EMI problems: Lap-top computers
(without phone or fax), cordless phones, TV sets or AM/FM radios, CD or tape
players.
EM energy rapidly becomes more intense as you get closer to the source. For
this reason, EMI from handheld devices is of special concern. A person using
one of these devices can bring high levels of EM energy very close to a power
chair without the user's knowledge.
Immunity level
The level of EM is measured in volts per metre (V/m). Every power wheelchair
can resist EMI up to a certain level. This is called its "immunity level". The higher
the immunity level, the less the risk of EMI. It is believed that a 20 V/m immunity
level will protect the power wheelchair user from the more common sources of
radio waves.
For the QM-710, the confi guration tested and found to be immune to at least 20
V/m is: a right-handed mounted joystick system, 18" seat width, 18" seat depth,
dual-post height-adjustable armrests, fi xed tapered legrests with one-piece solid
footplate and Gp 24 gel cell batteries.
The following dealer installed speciality input devices have an unknown effect on
the immunity level because they have not been tested with the Quickie control
systems:
•
Breath Control ("Sip n Puff")
•
Tri-Switch Head Array
• Proximity Head Array
• Proportional Mini-Joystick/Chin Control
•
Buddy Button
•
Wafer Board
PAGE 1.6
JANUARY 2012
Section 1
QM-7 SERIES SERVICE MANUAL
SUNRISE MEDICAL