Magic Extreme X8 Owner's Manual - page 47
Form 07D –Frontier V4 Owner’s Manual ENGLISH.docx
Revision No.2
© Magic Mobility
Page 47 of 48
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.