Invacare TRx Power Positioning System manual Electro-Magnetic Interference

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11.0 Electro-Magnetic Interference

Electromagnetic Interference Warning

!WARNING! It is very important that you read this information regarding the possible effects of electromagnetic interference on your TRx power positioning system.

In addition, operation of power positioning systems can create electro-magnetic interfer- ence, the effect of which cannot be determined. Please make sure to read the associated warnings in the owner's manual for your power base.

Electromagnetic Interference (EMI) From Radio Wave Sources

Power positioning systems 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 power positioning system to function by itself, or activate in unintended directions. It can also permanently damage the control system.

The intensity of the interfering EM energy can be measured in volts per meter (V/m). Each power posi- tioning system 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 radiat- ed 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.

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 trans- mitting unit) - examples include: cellular telephones, citizen band (CB) radios,"walkie-talkies", security, fire and police transceivers and other personal communication devices. NOTE: Some cellular telephones and similar devices transmit signals while they are "ON", even when they are not being used.

2.Medium range mobile transceivers, such as those used in police cars, fire trucks, ambulances, and taxis. These usually have the antennae mounted on the outside of the vehicle.

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 electric shavers and hair dryers, so far as we know, are not likely to cause EMI problems to your power wheelchair.

TRD0000, TRx Owner’s Manual- Rev. 5.0, January 20, 2005