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CCTV SYSTEMS. CCTV cables. CCTV SYSTEMS. Cable selection is a very important consideration in the performance of a CCTV system, especially where long distances need to be addressed.

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Cctv systems
CCTV SYSTEMS

CCTV cables


Cctv systems1
CCTV SYSTEMS

  • Cable selection is a very important consideration in the performance of a CCTV system, especially where long distances need to be addressed.

  • We will start with the low quality choices that are typically part of an out of the box solution and move through the cable hierarchy.


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CCTV SYSTEMS

  • As mentioned in an earlier lecture composite cables are usually bundled with low cost systems.

  • In the world of video composite cables consist of a red, white and yellow lead with RCA ends.

The red and white cables are your right and left audio cables, respectively. The yellow is a composite video cable.


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CCTV SYSTEMS

  • For CCTV applications the red lead is power, the yellow lead provides the video feed and the white lead is for audio if applicable.

  • Because these cables are

    premade it is important to

    make sure the red male lead

    is installed at the camera

    end.


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CCTV SYSTEMS

  • Composite cables are thin gauge and generally only good for 100 to 200 feet.

  • These cables are also easily susceptible to damage if not installed carefully and they do not provide much protection from EMI (electro magnetic interference) or RFI (radio frequency interference).


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CCTV SYSTEMS

  • Two sets of pre terminated composite cables can be connected together with barrel connectors.

  • If the RCA ends break off you will have to solder on new ones which is a time consuming process.


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CCTV SYSTEMS

  • Coax has historically been the cable of choice for CCTV systems, RG-59U being the most commonly used type of coax.

  • Its important to understand the construction of coax cable, almost all coax types are constructed in a similar fashion with very few exceptions.


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CCTV SYSTEMS

  • Here are the 4 parts of a coax cable, the foil shield and braid are considered to be the same and they serve the same function.


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CCTV SYSTEMS

  • What do you think is the primary function of the braid/shield of a coax cable is for?

  • The braid is grounded at the equipment (technical ground) and serves to discharge any induced EMI.

To control EMI and RFI


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CCTV SYSTEMS

  • RG-59U is what the majority of CCTV installations utilize and can be ordered with two 18 gauge conductors for power.

  • These are called siamese cables the two 18AWG are bonded to the jacket of the RG-59 cable.

ONE OF THE SPECIFICATIONS FOR CCTV IS A COPPER BRAID


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CCTV SYSTEMS

  • RG-59U is terminated with BNC (bayonet Neil Councelman) connectors which are a twist and lock style connector with a separate bayonet that covers the center conductor of the coax cable.

COMPRESSION

CRIMP

TWIST ON


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CCTV SYSTEMS

  • Today compression fittings are the most popular and commonly used types of connectors in the industry.

  • It is important to not allow any strand of the braid to come in contact with the center conductor when terminating fittings onto coax.

BNC COMPRESSION FITTING

COMPRESSION TOOL


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CCTV SYSTEMS

  • RG-59 is usually specified for 750 to 1000’ feet, beyond this limit the video resolution will start to degrade especially in color systems that operate at higher frequencies.

  • To overcome this distance limitation we would step up to the next higher grade and gauge coax which is RG-6U sometimes referred to as “series 6”.


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CCTV SYSTEMS

  • When specifying BNC connectors it is important to get connectors for specific cable types, RG-59 BNCs will not work on RG-6 cable and vice versa.

  • RG-6 can be installed upwards to 1500 feet before we would need to move up to the next grade of cable.


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CCTV SYSTEMS

  • We can increase the length of the RG-59 and RG-6 cables by installing video amplifiers, these devices can double the length of the cable runs.


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CCTV SYSTEMS

  • RG-11 would be the next logical choice since it is a thicker coax cable essentially providing lower loss over longer distances.

  • RG-11 is rarely used, instead video amplifiers would be installed, for distances of several miles RG-11 still would not be applicable.

  • Any idea what cable would be used where distances are measured in miles?


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CCTV SYSTEMS

  • Optical fiber would be used for very long distances.

  • A fiber to coax transceiver (media converter) would be required to convert the video signal to be accept by the camera and DVR.

  • The DOT cameras are all connected by fiber optics.


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CCTV SYSTEMS

  • Many of the newer CCTV systems are designed for UTP (unshielded twisted pair) which means that the existing infrastructure of network cabling can be utilized.

  • Cameras can be ordered with RJ-45 ports to accept twisted pair cabling.


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CCTV SYSTEMS

  • When using UTP (CAT 5e/6) for camera installs, what is the distance limitations?

  • These types of cameras will generally be plugged into a PoE (power over Ethernet) switch that can provide remote power to the camera.

328 feet or 100 meters which is the full channel length.


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CCTV SYSTEMS

  • So the bottom line is that RG-59U is the cable that is most likely to be used for the CCTV install.

  • The impedance of RG-59, RG-6 and RG-11 is 75Ω.

  • There are some basic cabling standards associated with installing any type of coax cable.


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CCTV SYSTEMS

  • The pulling force for coax is 35 foot pounds.

  • The bend radius for coax is 10 times the diameter.

  • The cable quality is dependent on the precision and uniformity of the center core, dielectric and the braid/shield.


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CCTV SYSTEMS

  • Sharp bends and tight loops affect the cable uniformity and consequently the impedance which results in high frequency losses and image reflections.


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CCTV SYSTEMS

  • When using siamese coax cable the two 18 gauge conductors will be terminated with spade style electrical connectors since these will terminate onto screw terminals.


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