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Chapter 3
3–2
Site Survey with Office DECT 8000
! Take into account radio interference caused by objects such as trees, walls and glass. Try to
install in an open environment where masking by objects is minimised. Refer to Table 2 for
details.
When installing cables for DBSs, keep them away from high-speed LAN cables and power ca-
!
bles which can cause electrical interference. Maintain at least 1m distance.
Avoid installing a DBS near windows since radio interference between floors of a building
!
might be more active due to diffraction of radio waves.
It is recommended that a DBS should be installed at a distance of 2m from the floor and
!
30cm from the ceiling, and cables should come from the ceiling rather than the floor.
The distance between each DBS should be at least 3m.
!
Take into account interference from adjacent cells when the DECT system is installed in a
!
multi-storey building.
For overlapped and multi-cell systems, the distance between DBSs should ideally be about 30
!
– 50m for indoor use, and about 300m for open outdoor areas. However, these values are
rarely achieved in practice due to the variable environmental characteristics of sites. The dis-
tance should be measured carefully site by site.
Take into account the following characteristics of radio waves.
!
Body effect:
- - - -
The RSSI value may differ depending on the location of the handset on the human body.
Speed of moving handset:
- - - -
The RSSI value may fluctuate if a handset moves at speed.
Line of sight:
- - - -
Much more consideration is required when a DBS is to be installed in a wide-open area.
Multi-storey deployment:
- - - -
Characteristics of cells in each storey may differ due to the structure and materials of the
building.
Table 2: Radio Interference by Materials
Material
Glass
Glass, metal reinforced grid
Glass, metal-clad sunguard
Wall, indoor, wood
Wall, brick, 10cm
Wall concrete, 15cm
Wall concrete, 20cm, large win-
dows
Wall concrete, 40cm
Concrete
Concrete, metal clad
Concrete, window
Venetian blinds open
Venetian blinds closed
Soft partitioning
Approximate Loss in dB
2
10
10
2
3.5
9
6
17
15
30
8–9
10
20
3–4
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