TECHNICAL REFERENCE AND USER’S GUIDE
REV A
GSM GATEWAY
EXTERNAL ANTENNA CONNECTIONS
The external antennas that come with GT20 should be connected to the connection
points that have specially designed for them. The cable length of the external antennas
is 2 meters. The antennas that will be employed should be fixed as far away from each
other and GT20 as possible in order not to affect each other. Because of the similar
reasons, it is recommended that GT20 and the antennas should be installed away from
the exchange and telephones.
WARNING
THE ANTENNAS THAT ARE CLOSE TO EACH OTHER OR GT20 MAY CAUSE NOISE TO BE
HEARD DURING CONVERSATIONS.
While determining the locations for the external antennas and GT20 choosing locations
where GSM coverage is powerful is essential for the quality of conversations. In this regard,
it is recommended that the installation should be made to spots that are close to the outer
front of the buildings and the external antennas should be attached to the outer front walls.
The connections of the external antennas to GT20 are shown in Figure -11.
The metal holders for the external antennas are installed on the sites determined with
respect to the constaints explained above. If the site has a clean and smooth surface, the
paper at the back of the holder is removed and the holders are sticked on the surface. If
the surface is dusty and shaggy (rough plaster, wooden etc.) then the holders are fixed
with the screw pair given with the antennas.
After making all these connections, the front cover of the module is closed.
After that stage, some operations may be carried out in order to check the statuses of
installation of the GT20 GSM Gateway and GSM network signal level. For that reason,
primarily, while GT20 is operating, as will be explained in the next chapter, the PIN
codes must be entered to the SIM cards on GT20. Then the signal level should be
observed by the LEDs on the front cover according to the locations of the external
antennas. If the LEDs signifying the signal level are blinking fast, then this indicates
that the installation has been accomplished and the GT20 GSM Gateway is ready for
communication programming.
TELEPHONE OR EXCHANGE EXTERNAL LINE CONNECTION
There is a clip-type socket on GT20. The two-wire cable coming from telephones or the
external lines of the exchange is connected to the clip-type connectors with springs that
are on the GT20/GT10 card. That connection has been illustrated in the figure below.
GT20 can be connected over 0.5 mm copper cable at distances up to 2 kms from the
exchange or telephones.
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Figure-13
Figure-14