PI - 32.15a
Product Documentation of the LSN Radio Fire Detection System
Seite 8 von 32
601-F.01U.002.708
A3.en / 28.12.2004
ST-FIR/ PRM1 / deh
3.1. Planning a radio cell
The range that can be achieved by a radio system in a building is
generally dependent on the reflection and absorption responses of
the materials used and on the design of the ceilings and walls!
.
There is no need for a visual line between the radio components!
Limiting value when planning a transmission path
Total attenuation of a transmission path < 90dB.
Relationship between distance and attenuation with a visual line
.
In buildings, doubling the distance between the RF expansion module and the RF
detector results in an attenuation increase of 16 to 17dB.
Distance
40m
30m
25m
20m
15m
10m
5m
Attenuation
90dB
83dB
79dB
74dB
67dB
57dB
40dB
Walls and ceilings in buildings cause additional attenuation of the radio signal.
D
The attenuation values of the construction elements in question (walls, ceilings)
must also be added to determine the actual attenuation at the mounting location in
the case of attenuation owing to the distance.
Attenuation values for constructions frequently used in buildings
Construction
Additional attenuation
Partition
Very low
1dB
Dry brick wall or concrete wall/ceiling
Low
6dB
Lime sand brick
Moderate
6dB
Sand lime brick planning elements
Moderate
10dB
Wood skeleton wall/wood panel wall
Moderate
10dB
Damp brick wall
Moderate
10dB
Coated gypsum plasterboard (double wall)
High
15dB
Reinforced concrete
High
30dB
Thick, damp brick wall
Very high
40dB