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Part 1: Site Survey and Overview of DECT Systems
Positioning Base Stations
The coverage area for a Base Station within a building varies from 50 to 150 metres.
The radiation graph from a Base Station is almost circular, horizontally, when working
in "free" areas. If a Base Station is placed in the corner of a building, part of the cov-
erage area is outside the building (Figure 1.1). This means that a Base Station
should not be placed in the corner of a building if the required coverage area is within
the building. The shaded area in Figure 1.1 is the "unexploited" area. In practice the
radiation graph will not be as neat as in Figure 1.1, but it is a good starting position
for planning the installation during the site survey phase.
Figure 1.1
A Base Station should be placed at a minimum height of two metres. If the Base Sta-
tion is any lower, people moving around the building could affect the radio signal from
the Base Station. If the Base Station is placed too high, especially in buildings with a
steel roof, steel girders and/or large air shafts in the ceiling, there is a risk of gaps in
the coverage area. This is party due to "shadows" and/or reflections. The design of
the building, and especially equipment made of metal (shelving, racking, machinery
etc) may effect the radio signals a great deal. For example, in a warehouse where
goods are moving in and out constantly the quality of radio signals can vary from day
to day. Refer to section 1 for more information.
Using the Demonstration Base Station
To find the correct place to locate a Base Station, the Deployment Base Station in-
cluded in the DECT Demonstration and Installation Kit can be used. Refer to the ex-
ample in Figure 1.2. In practice, this method will not result in a symmetric solution as
shown in Figure 1.2, but it does ensure optimum placing of the Base Stations.
A survey and demonstration Base Station is placed in the corner of the building (posi-
tion 1 or 2). The broken circle indicates the coverage area to be measured for the
Base Station. The coverage of the area is defined by the fact that an RSSI value of
85dBm can be measured along the broken line.
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