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14 www.pridemobility.com Jazzy 1100/RevJ/Feb03
III. EMI/RFI
Laboratory tests performed by the Food and Drug Administration (FDA) have shown that radio waves can
cause unintended motion of powered wheelchairs. Radio waves are a form of electromagnetic energy (EM).
When this energy adversely 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 powered wheelchairs.
EMI/RFIFREQUENTLY ASKED QUESTIONS (FAQS)
The following FAQs summarize what you should know about EMI/RFI. Use this information to minimize
the risk that EMI/RFI will affect your powered wheelchair.
Where do radio waves come from?
Radio waves are emitted from the antennas of cellular phones, mobile two-way radios (such as walkie-
talkies), radio stations, TV stations, amateur radio (HAM) transmitters, wireless computer links, micro-
wave sources, and paging transmitters. Radio waves are a form of EM. Because electromagnetic energy is
more intense closer to the transmitting antenna (source of emission), the EM fields from two-way radios
are of special concern to powered wheelchair users.
If my powered wheelchair is affected by EMI/RFI, what kind of motion should I expect?
This is hard to predict. It would depend on a number of factors:
n Strength of the radio waves
n Construction of the powered wheelchair
n Position of the powered wheelchair (whether it is on level ground or on an incline)
n Whether or not the powered wheelchair is in motion
An affected wheelchairs movement can be erratic. It may move by itself or come to a sudden stop. Further-
more, it is possible for EMI/RFI to unexpectedly release the brakes on a powered wheelchair. Some intense
sources of EMI/RFI can even damage the control system of your Jazzy.
Is there any way to know for sure whether radio waves are responsible for the unintended motion
of my powered wheelchair?
Unfortunately, interference from radio wave sources may be difficult to recognize, since 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 powered wheelchair 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 powered wheelchairs?
The FDA has reports of injuries that resulted from the apparent uncontrolled motion of powered wheel-
chairs. However, it is unclear how many of these incidents were actually caused by radio wave interference.