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C. SOURCES OF EMI
The sources of EMI fall into three broad types:
1. Hand-Held Transceivers:
The antenna is usually mounted directly on the unit. These include:
•Citizens band (CB) radios
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•Security, fire and police radios
•Cellular phones
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•Other personal communication devices
NOTE– These devices can transmit signals while they are on, even if not in use.
2. Medium-Range Mobile Transceivers:
These include
3. Long-Range Transceivers:
These include commercial radio and TV broadcast antenna towers and
amateur (HAM) radios. NOTE– The following are not likely to cause EMI problems: Lap- top computers (without phone or fax), Cordless phones, TV sets or AM/FM radios, CD or tape players.
D. DISTANCE FROM THE SOURCE
EM energy rapidly becomes more intense as you get closer to the source. For this rea- son, EMI from
E.IMMUNITY LEVEL
1.The level of EM is measured in volts per meter (V/m). Every power wheelchair can resist EMI up to a certain level. This is called its “immunity level”.
2.The higher the immunity level, the less the risk of EMI. It is believed that a
20 V/m immunity level will protect the power wheelchair user from the more common sources of radio waves.
3.The configuration tested and found to be immune to at least 20 V/m is:
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4.The following specialty input devices have an unknown effect on the immunity level because they have not been tested with the
•Breath Control | • Proportional Head Control |
• Proportional | |
•Heavy Duty Switched Joystick | • Buddy Button |
•Treadle Switch | • Micro Light |
•Ribbon Switch | • Star Board |
•Proximity Head Array | • Wafer Board |
•Zero Touch Switch | • Penta Switch |
• Plate Switch | |
• Soft Switch | |
•Disc Switch | • Grasp Switch |
•Wobble Switch |
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Individuals with physical limitations requiring the use of a specialty control input device known not to be immune to 20V/m, or not known, should exer- cise extra care around known sources of EMI.
There is no way to know the effect on EMI if you add accessories or modify this chair. Any change to your chair may increase the risk of EMI. Parts not specifically tested or parts from other suppliers have unknown EMI properties.
F. REPORT ALL SUSPECTED EMI INCIDENTS
You should promptly report any unintended movement or brake release. Be sure to indicate whether there was a radio wave source near your chair at the time. Contact:
Sunrise Medical, Customer Service Department at (800)
G. EMI FROM CHAIR
The chair itself can disturb the performance of electromagnetic fields such as emitted by alarm systems of shops.
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