Type Of Cable - Videotec TWM 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. 5 100 ohm (in the case of 4 pairs).
MAXIMUM DISTANCE 1 VIDEO PAIR
MAXIMUM DISTANCE 4 VIDEO PAIRS
Loss
(maximum)
21 dB/km @ 1 Mhz 62 dB/km @ 1 Mhz
43 dB/km @ 4 Mhz 53 dB/km @ 4 Mhz
65 dB/km @10 Mhz 47 dB/km @ 10 Mhz
N.E.X.T. Resistance (max.)
(minimum)
192 ohm/km
COLOUR
1500m
1000m
Pag. 6
Diameter Insulation
24 AWG** PE
B/W
2000m
1000m
TWM 2701