How Cable TV Works

Early cable TV systems operated on the principle of tree and branch. It consisted of an antenna for receiving over the air broadcast programs, a building called a headend for combining the programs received and a trunk distribution system of booster amplifiers and coaxial cables for delivery of the programs to customers.

In the 1970s, the antenna was replaced with a satellite earth station and the trunk system with microwave links to what are called hub sites. With the introduction of commercially practical fiber optic cables in the late 1980s, a significant advancement in improving the quality and reliability of the cable network became possible.

Today, Cox Communications engineers have designed a Hybrid Fiber Coax (HFC) network with a unique configuration called "ring-in-ring." A primary fiber optic ring covers a large geographical area, such as your city or community, and carries signals in a circular path around the ring. Connecting to the primary ring are groups of secondary rings serving smaller areas. Finally, grouped around each secondary ring are fiber optic "nodes." The nodes function to convert the optical signals back into a standard broadcast form for distribution to the consumer.

The purpose of these optical rings is to insure uninterrupted service to you, the customer. For example, in the event of a loss of signal flow from one direction around the primary ring, a sensor located at each secondary ring will detect this loss, automatically switch to an alternative route and then send a high priority maintenance signal back to the system office. The result is a network that provides a reliability of 99.99 percent.