CCTV and Security DVR system consists of many components and each one of them is critical to the quality of the video picture. Many Security camera installers specify very specific criteria for the security cameras and security DVR type they are using; however, when it comes to the transmission media, very few of them know the and understand the subject.
 

Selecting the correct cable/ media for security camera application (CCTV) is one of the most important aspects of designing and implementing a quality security DVR system and yet it is the least understood subject. You can purchase the highest quality security camera or DVR, but if the video signal is not transmitted by the proper media/ cable, the result will affect the entire solution. Most of the common video signal problems with picture quality can be fixed by selecting the proper cable in advance and following proper installation techniques and procedures.
 

Coaxial Cable Types
Most Security camera video signals are transmitted using coaxial cable. Coaxial cable is designed to transmit the complete video frequency range with minimum distortion or attenuation, making it an excellent choice for CCTV application. However, there are number of coaxial cable to choose from, and choosing the incorrect coaxial cable can degrade the overall signal transmission quality.

There are various types for coaxial cable. Understanding the various type of coaxial cable and selecting the right cable for a security camera, CCTV system will eliminate video quality problems, money, and aggravation. A security camera video signal is comprised of both low frequency and high frequency components. Selecting the right cable for the job will eliminate distortion or attenuation.

Coaxial Cable Parameters
Coaxial Cable specification varies depending on the type of coax cable type. All type of Coaxial cables has impedance. The impedance of security camera/CCTV equipment is 75 ohms; therefore in order to have minimum losses, it is important to choose a cable with a matching impedance of 75 ohms. If cable that have lower or higher impedances used (50 ohm or 93 ohm) , then you will experience signal loss and reflection resulting in short distance transmission and poor picture quality. Coaxial cables are identified by the RG type. RG stands for Radio Guide. 75 ohm coaxial cable has number sizes. The most common type are RG 59, RG 6, and RG 11. An RG 59 cable is the most commonly used for security camera application, because it’s a thinner in diameter and easy to work with. The RG 11 cable is the thickest and harder to work with. The RG 6 size is between the two. The difference between the RG types is not just size, but also the attenuation, which will affect the transmission distance. Coax cable transmission limitations for CCTV will be as follows:
RG-59:   750-1000 ft.
RG 6  :   1000 – 1500 ft
RG-11:   1500 – 2500 ft

CAT5 Cabling for CCTV  Cat 5 cabling is widely use today for CCTV security camera application. Cat 5 and balun ( see picture below) allow traditional 75 ohm coax cable to be replaced by Category 5 (or better) twisted pair in the CCTV security and surveillance environment, thereby allowing CCTV camera and monitoring equipment to be deployed by UTP cable (unshielded Twisted Pair ) or cat 5 cable provides a low cost means of sending video for distances of up to 1,000 feet black & white and 600 feet color.