7
CAUTION:
IT IS VERY IMPORTANT THAT YOU READ THIS
INFORMATION REGARDING THE POSSIBLE EFFECTS OF
ELECTROMAGNETIC INTERFERENCE ON YOUR POWERED
SCOOTER.
Electromagnetic Interference (EMI) From Radio Wave Sources
Powered wheelchairs and motorized scooters (in this text, both will
be referred to as 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
certain intensity. This is called its “immunity lever.” The higher the
immunity level is, 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. The immunity level of this powered scooter as shipped, with no
further modification, is not known.
There are ample 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 minimized.
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, ambulances, 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.
