User's Manual

DMR repeater 18/02/2011 Versione 1.3
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of tolerance), it is possible to calculate the minimum distance of people from the antenna by using the
following equation for RF power decay in free space (far field):
S = ( P x G / 4 x π r2 )
where:
S = maximum power density
P = maximum transmitted RF power
G = antenna gain
R = distance from antenna.
This gives:
r =
√ ( P x G / S x 4 x π )
For VHF (150-174MHz) equipments the minimum safety distance is r = 2,75 m.
For UHF (407-470MHz) equipments the minimum safety distance is r = 2,36 m.
5.3.6 AF INTERFACE
If a 2/4W telephone line is connected to the equipment, external primary discharges are recommended to
prevent damages due to eventual atmospheric discharges on the line. The internal AF interface is protected
only by secondary dischargers.
5.3.7 MANUAL SETTINGS
The equipments of RA-xxx series are designed to minimize the set of needed hardware settings. Before
installing the equipments the following manual settings must be verified if digital I/O and AF interface are used
respectively:
∞ voltage polarity, used to supply the optically isolated digital input contacts: inside PSU module, a 4
poles dip-switch allows to set the polarity, according the following table:
1 ON
2 ON
3 OFF
4 OFF
+12V
1 OFF
2 OFF
3 ON
4 ON
-12V
∞ AF line interface characteristics: inside I/O module, a 2 pole dip-switch allows to set the line type (2W
or 4W) and the input impedance of eventual 4W line (600 ohm or high), according the following table:
1 ON
Zin (4W) = 600 ohm