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14 www.pridemobility.com Jet 2/Rev F/Feb03
III. EMI/RFI
EMI/RFI WARNINGS
Laboratory tests performed by the Food and Drug Administration (FDA) have shown that radio waves can cause
unintended motion of electric mobility vehicles. Radio waves are a form of electromagnetic energy (EM). When
this energy unintentionally affects the operation of an electronic device, it is called Electromagnetic Interference
(EMI) or Radio Frequency Interference (RFI).
WARNING! Radio waves may interfere with the control of power chairs.
FREQUENTLY ASKED QUESTIONS (FAQS)
The following FAQs summarize what you should know about EMI/RFI. Use this information to minimize the risk
that EMI/RFI may affect your power chair.
Where do radio waves come from?
Radio waves are emitted from the antennas of cellular phones, mobile two-way radios, walkie-talkies, radio
stations, TV stations, amateur radio (HAM) transmitters, wireless computer links, microwave sources, and paging
transmitters. Radio waves are a form of electromagnetic energy (EM). EM is more intense closer to transmitting
antennas, which are sources of emission. The greater the transmission strength, the greater the concern to electric
mobility vehicle users.
If my power chair is affected by EMI/RFI, what kind of motion should I expect?
This is hard to predict. The effect may depend on a number of factors including:
n Strength of the radio waves
n Construction of the electric mobility vehicle
n Position of the power chair (whether it is on level ground or on a slope)
n Whether or not the electric mobility vehicle is in motion
Electric mobility vehicle motion caused by EMI/RFI can be erratic. The vehicle may move by itself or come to a
sudden stop. Furthermore, it is possible for EMI/RFI to unexpectedly release the brakes on an electric mobility
vehicle. Some intense sources of EMI/RFI can even damage the control system of an electric mobility vehicle.
Is there any way to know for sure whether radio waves are responsible for the unintended motion
of my power chair?
Unfortunately, interference from radio wave sources may be difficult to recognize, because the signals from these
sources are invisible and may be intermittent. However, the FDA recommends that you report all incidents of
unintended motion or brake release to the electric mobility vehicle manufacturer and, if possible, note whether
there was a radio wave source nearby at the time of the incident.
Has anyone been hurt from erratic, unintended motion of electric mobility vehicles?
The FDA has reports of injuries that may have resulted from the uncontrolled motion of electric mobility vehicles.
However, it is unclear how many of these incidents were actually caused by radio wave interference.