Two of the most common home video cable types are coaxial and RCA, which may also be referred to as AV or component cables. Each can be used to connect cable boxes, DVD players and other devices to television sets.
Coaxial Cable Properties
The cable make-up is the unique feature of coaxial, or coax, cables. Inside the cable is a core wire, surrounded by a dielectric insulator, a shield made of woven copper wiring and finally an outer rubber or plastic insulator. This construction makes coaxial cabling resistant to external interference, which is why it is a popular way to connect satellite and cable television boxes to outside wiring. It can also be used to build physical computer networks. Coaxial cable can use a variety of connectors, but home video installations use almost exclusively use female threaded F-type connectors. Coaxial cabling used for television signals is rated at 75 ohms, while coax used for high power antennas, CCTV, computer networking and other installations may rate anywhere from 50 to 95 ohms.
RCA Cables Are Not Cables
People commonly refer to any cable that uses a phonograph connector as an RCA cable. Actually, there is no formal cable associated with the phonograph connector; it can use any two-wire cable. The RCA corporation introduced these connections at the time of World War II as an easy way to link phonographs to amplifiers. A simple, slip on connector that allows a ground and signal connection, it is well suited for both audio and video. RCA connectors are often colour coded to indicate their purpose. In a common AV cord yellow indicates video, red for right side audio, white for left side audio or mono. In a component analogue video cable, also called a YPbPr cable, a green connector indicates the luma, or Y signal. Blue is used for the difference between luma and blue, or Pb, and red for the difference between luma and red, or Pr. Typically, devices have female connectors and cables have male connectors.
It is extremely important to remember to turn off equipment, particularly audio devices, before connecting or disconnecting RCA cables.
RCA vs Coaxial Cable
Choosing which type of cable to use depends, of course, upon the application. If signal interference is a concern, coaxial cabling is probably the best option. When multiple signals are being used in a single application, such as in a home theatre surround sound system, RCA cables provide a cheap, reliable and easily installed option. An additional advantage of RCA connections is the standardised colour coding, which allows you to easily keep track of the purpose of each wire.