Type Of Cable; Switching On And Off - Videotec TWRB Manuel D'instructions

Type of cable

A UTP (Unshielded Twisted Pair) Cat. 5 cable type should be used (as defined in the TIA/EIA 568A and
ISO/IEC 11801 standards). Using this cable it is possible to cover long distances and run more than one video signal
(max.4) or telemetry signal along the same cable.
It is also possible to increase the distances using pairs of intermediate TWR/TWRB and TWT; in this case we
recommend keeping below 1500m for a single distance and using at most one intermediate pair so as not to impair the
video signal quality too much (in any case reasonable results can be obtained by adding another pair both in b/w and in
colour).
The following table shows the main properties of a Cat. 5 cable at 20 °C
Impedance
(1 - 100 MHz)
100 ohm ± 15 ohm *
* The most frequently used cables are 100 ohm
** Commonest diameter
Meaning of terms used:
Loss: Expressed in dB, depending on the frequency, it represents the amplitude decrease of a signal along the
conductor. Normally, the lower is the loss, the greater is the distance reachable.
N.E.X.T.: Near-End Crosstalk (sometimes called simply crosstalk ); expressed in dB, depends on the frequency;
indicates how much a signal interferes with another signal. Normally, the higher is the value, the less is the interference
of one signal with another.
AWG: American Wire Gauge, American system for measuring cable diameters.
e.g. 24 AWG corresponds to approx. 0.5 mm diameter
The following table shows the maximum distances reachable individually or with more than one pair for video signals in
colour or in black and white with a UTP cable 4x2x24AWG Cat. 5 100ohm (in the case of 4 pairs).
MAXIMUM DISTANCE 1 VIDEO PAIR
MAXIMUM DISTANCE 4 VIDEO PAIRS

Switching on and off

Before connecting the appliance:
• check that the material supplied corresponds to the specifications indicated on the data plate, following the chapter
Identification data
• check that TWRB/TWRR receiver and the other components of the installation are closed in order to avoid direct
contact with energized parts.
• make sure that all the parts are fixed in a solid and reliable way
• check that the electrical capacity and the connection cables will support the system power consumption
SWITCHING ON: the receiver has no switch : connect the unit.
SWITCHING OFF: disconnect the unit
Loss
(maximum)
21 dB/km @ 1 Mhz
43 dB/km @ 4 Mhz
65 dB/km @10 Mhz 47 dB/km @ 10 Mhz
N.E.X.T.
(minimum)
62 dB/km @ 1 Mhz
53 dB/km @ 4 Mhz
COLOUR
1500m
1000m
Pag. 7
Resistance Diameter
(max.)
192 ohm/km 24 AWG**
B/W
2000m
1000m
Insulation
PE
TWRB/TWRR 2701