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About Cables for CCTV Systems
Coaxial cable has proper electrical features to transmit the video signals from the camera to the monitor. Among various coaxial cables, RG59/U is most common with a 75-ohm impedance and can be installed up to 450ft distance without loosing the video quality. This cable is usually connected by BNC connectors at both ends.
Fiber-Optic Cable is not affected by electrical interference and has no problem even in contact with high-voltage power. It transmits video signals with extremely high efficiency and can run up to miles. The problem is that it is expensive and difficult to handle.
RCA cable is not standard in the industry but is used a lot, specially for short distances up to 250ft. Twisted wire from 14 to 24 AWG (American Wire Gauge) with RCA connections at both ends will work as RCA cable. Even though its transmission quality is not as good as Coaxial Cable or Fiber-Optic, RCA cable is widely used because it is very easy to handle and has no problem of loosing video signal up to 250ft distance.
Most observation systems which are pre-assembled at the factory have DIN cables with DIN connectors at both ends. DIN cables have 5 or 6 wires inside the configuration of which is, for example; wire 1 is for video, wire 2 is for audio, wire 3 is for power(12VDC, positive), wire 4 and 5 are for speaker(positive and negative), wire 6 is for ground. Mini DIN cable, which is used for mini camera package, comes with 4 wires inside. DIN cable, large or mini, can run up to 250 ft distance without loosing the video quality.
Because the transmission of video signals is directly related to the spacing between the inner wires or conductor and shield, any changes in the distance between the wires or conductor and shield will degrade the picture quality. This change may be caused by tight bends, kinking, indentations, stapling or others. That's why you need to use suitable cable tie which are sold at any hardware or electrical parts shops when working with Coaxial Cable or DIN cable.
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