Section 2—emi information – Invacare TDX SP User Manual
Page 20
SECTION 2—EMI INFORMATION
20
SECTION 2—EMI INFORMATION
ƽ WARNING
CAUTION: IT IS VERY IMPORTANT THAT YOU READ THIS INFORMATION
REGARDING THE POSSIBLE EFFECTS OF ELECTROMAGNETIC
INTERFERENCE ON YOUR POWERED WHEELCHAIR.
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 metre (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.
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 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.
NOTE: Other types of hand-held devices, such as cordless phones, laptop computers,
AM/FM radios, TV sets, CD players, cassette players, and small appliances, such as elec-
tric shavers and hair dryers, so far as we know, are not likely to cause EMI problems to
your powered wheelchair.