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4.3 INSTALACIONES DE VÍDEO: INTRODUCCIÓN.
VIDEO INSTALLATIONS: INTRODUCTION.
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The connection of audio/data between the main internal and
external accesses is made with the cables connected to terminal
block 3P of each street panel. The cables joining the different
terminal blocks 1P , 2P and 3P constitute the external bus of the
street panels.
In each block of dwellings, the main internal access is connected
to the dwellings and to the secondary accesses by means of
an internal dwelling bus. Each internal bus is formed by the
cables leaving from terminal blocks 1M, 2M and 3M of the main
internal street panel audio control group, which connect to
terminal blocks 1M, 2M and 3M of the secondary accesses and
the telephones in the dwellings.
The video signal can be distributed both by means of 75 ohm
coaxial cable and with a category 5 twisted pair cable (100
ohms). Although the installations are similar for both cables
there are some differences that must be taken into account:
• The resistance at the end of the line has a different value:
75 ohms for coaxial cable and 100 ohms for twisted pair.
By default, monitors are configured by means of a bridge
with the resistance corresponding to coaxial cable (75
ohms).
• The default configuration of cameras is also for coaxial cable
(75 ohms). Point 4.4 shows how to configure the camera
bridges according to the type of cable installed.
• The video distributors are different depending on whether
coaxial or twisted pair cable is installed.
IMPORTANT: The connection of the video cable between
the external bus and the internal buses is performed by
means of distributors. The number of distributors will
depend on the characteristics of the installation; it is not
necessary to use one distributor per main internal street
panel. In blocks with secondary accesses, the video cable
starts at main internal street panel and, in order, runs
along the secondary access street panels, going up to
the dwellings from the last of these accesses. See the
example in point 4.7.
The distributors receive the power supply in a different manner,
according to the type of cable used and their position in the
installation:
•From monitors in installations with coaxial cable: by means
of a cable from the power supply output for distributors
(terminal block 14) of each of the monitors connected to
the derivating outputs of the distributor.
•From the main internal street panel in installations with coaxial
cable: by means of a cable from the power supply output
for distributors (terminal block 14) of the street panel
connected to the distributor.
•From monitors in installations with twisted pair: apart from
the cable indicated in the first point, cable number 2 (2P or
2M) of the digital bus will also be connected to the distributor.
•From the street panel in installations with twisted pair: apart
from the cable indicated in the first point, cable number 2
(2P or 2M) of the digital bus, or a cable from terminal block
15 of the street panel audio group, will also be connected
to the distributor.
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