Transmission Field - Siemens FDCW221 Technical Manual

Radio gateway, radio smoke detector, manual call point, radio base
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4.3 Transmission field

Building Technologies
Fire Safety
In the open, the field strength falls with a factor of 1/r², i.e. a doubling of distance in
the open equates to a 6 dB increase in damping. In buildings, the factor in a first
approximation is 1/r
, i.e. a doubling of distance means that damping increases by
5
around 6 to 17 dB.
The table below illustrates the relationship between distance and damping for the
line of sight in the building:
Distance [m]
40
Damping [dB]
90
Maximum values: Distance 40 m / damping 90 dB
Table for converting to linear values
Damping factor
1
Damping [dB]
0
The transmission field in the building is affected by walls and obstacles. These
constructions (walls, ceilings etc.) must be analyzed in detail to obtain a
statement on damping.
Radio damping when passing through obstacles
The approximate values listed in the table should be added together for
constructions encountered along the radio link in order to determine the actual
damping at the receiver location.
Construction
Room divider
Dry bricks
Dry concrete
Lime sand brick
Planar lime sand brick elements
Timber frame wall
Timber panel wall
30
25
20
83
79
74
4
10
50
6
10
17
Additional damping
<1 dB
around 6 dB
around 6 dB
around 8 dB
around 8 dB
around 8 dB
around 8 dB
Planning
4
Transmission field
15
10
5
67
57
40
100
1000
20
30
45 | 82
009865_m_en_--
2015-11-06

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