Magic Extreme X8 Owner's Manual - page 45
Page 45
Appendix B – Electromagnetic Interference (EMI)
Electromagnetic Interference (EMI) From Radio Wave Sources
Powered Wheelchairs 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 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 “immunity 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. This powered wheelchair model as shipped, with no further modification,
has an unknown immunity. 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 minimised.
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, ambulance, 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 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.
Powered Wheelchair 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 wave sources (transceivers) are of special concern. It is
possible to unintentionally bring high levels of EM energy very close to the powered wheelchair’s
control system while using these devices. This can affect powered wheelchair movement and
braking. Therefore, the warnings listed below are recommended to prevent possible interference
with the control system of the powered wheelchair
.
WARNINGS
Electromagnetic interference (EMI) from sources such as radio and TV stations, amateur radio
(HAM) transmitters, two way radios and cellular phones can affect powered wheelchairs.
Following the warnings listed below should reduce the chance of unintended brake release or
powered wheelchair movement which could result in serious injury.
Do not operate hand held transceivers (transmitter-receivers), such as citizens band (CB) radios, or
turn ON personal communication devices, such as cellular phones, while the powered wheelchair is