16
Projecting the DECT network
Material characteristics and interference factors
There are a number of interference factors that influence the range and quality of the
transmission in particular. The types of interference factors include:
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Interference as a result of obstacles that diminish the signal transmission, creating
radio shadows
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Interference through reflection that restricts the call quality (e.g., crackling or back-
ground noise)
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Interference through other radio signals that can lead to errors in transmission
Interference through obstacles
Possible obstacles are:
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Building constructions and installations such as reinforced concrete ceilings and walls,
stairwells, long corridors with fire doors, uptakes and cable channels.
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Metal-clad rooms and objects such as cold stores, computer rooms, metallised glass
areas (reflections), firewalls, tank systems, refrigerators, electrical boilers etc.
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Movable metal objects such as lifts, cranes, carts, escalators, shutters
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Room furnishings such as metal shelves, filing cabinets
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Electronic devices.
It is often difficult to locate the exact source of the interference; particularly if the recep-
tion power of the local DECT signals fluctuates strongly within a few centimetres. In these
cases, the interference can be reduced or corrected by small changes to the position.
Loss of range through building materials in comparison to a free wireless
field:
Please note
Wireless coverage in lifts is normally poor or not available at all (
Glass, wood, untreated
Approx. 10%
Wood, treated
Approx. 25%
Plasterboard
Approx. 27 – 41%
Brick wall, 10 to 12 cm
Approx. 44%
Brick wall, 24 cm
Approx. 60%
Aerated concrete wall
Approx. 78%
Wired glass wall
Approx. 84%
Reinforced concrete ceiling
Approx. 75 – 87%
Metal-coated glass
Approx. 100%
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