Coaxial Cable Selection for CCTV
RG-59/U is a designator for 75-ohm impedance coaxial cable which is mostly use in surveillance system ir CCTV installations there are several varieties of CCTV cables,
each having some different characteristics, such as RG-6/U (18 AWG) and RG-11/U (16 AWG). These have larger gauge center conductors and are for use where longer cable runs are needed to install security camera at a long distance.Two important known characteristics of coaxial cable are the gauge, or diameter, of the center conductor, and the type of shield surrounding the center conductor. A larger diameter center conductor will have less signal loss for a given distance.
Typical gauges available for CCTV and surveillance system install are RG-59 cables in 20 AWG (American Wire Gauge), 22 AWG, and 23
The second vary important characteristic is the shielding. Cable for CCTV and security camera use should have a 95% coverage copper braided shield. The shield must be effective by conducting any externally induced voltages to ground. A good shield and a good electrical connection to the connector are of prime concern to produce high quality security system picture, especially at long distance camera install.
Cable Types available to you:CATV cable typically has a copper-coated, solid steel center conductor and the shield is typically aluminum foil with a 40% aluminum braid. It does not make good connections with BNC-style connectors, and for that reason not recommended for CCTV and security camera install in particular, the twist-on style. The jacket of the cable is usually marked CATV indicating that this cable is designed for Community Antenna Television systems. Another marking you can see on cables are , MATV Master Antenna Television is also sometimes seen. Either marking indicates a cable construction designed for significantly higher frequency ranges than found in CCTV or any security DVR or security Camera application. CATV or MATV cable should never be used for CCTV systems.
The Cables that are mostly design for CCTV systems should have a good 95% coverage, braided-copper shield and a center conductor of 20 or 22 AWG copper fro Example the RG59 and Siamese, which include power and RG59 in one. The use of copper conductors is important in the frequency ranges used for base-band CCTV signals.
This type of RG59 cables is available in both stranded and solid center conductors. Stranded conductor would perform better where flexibility is a requirement, such as a camera mounted on a pan & tilt scanner assembly or in making connections to a chassis that is mounted on slides within a rack.
Twisted-pair cable, is another option for sending an Video signal to long distances CAT 5 cable is most commonly use for digital network communication, but when use with a proper Baluns, you can use this cable for security camera and CCTV application. The CAT 5 is more economical. But its impedance and signal characteristics differ from those of coax. You can’t just attach it directly to video inputs and outputs.
It is vary important to know cable picture quality performance on long run so we can are installation and avoid un necessary cost
Cable Distance Limitations