Cable TV System Basics

This page provides a tutorial covering the basics of a Cable TV system. It explains the different modules within the system, including the cable station, multiplexer, amplifier, cable, feeders, and the cable TV box. Cable TV is a system where TV signals are delivered to users using coaxial cable, rather than relying on radio waves.

A cable TV company gathers various TV signals and combines them through a process called multiplexing. This multiplexed signal is then distributed to subscribers. A channel decoder box, located at the subscriber’s home, selects the desired channel and sends it to the TV set.

Cable TV system basics

The complete cable TV system is shown in the figure above. CATV companies provide cable TV service. Let’s break down the entire process step-by-step:

• Signal Collection: Cable TV companies collect broadcast TV signals using high-gain TV antennas. This location is often referred to as the “headend.” The received TV signal programming is then re-distributed.

• Multiplexing and Amplification: The collected signals, which are at different frequencies, are multiplexed (combined) and amplified to strengthen the signal.

• Distribution: This amplified signal is distributed to subscriber homes via coaxial or fiber optic cables. The coaxial cable is typically a 75 Ohm RG-59/U cable.

• Cable Box and Channel Selection: The signal connects to a cable box inside the subscriber’s home. This cable box contains a local oscillator or synthesizer. Based on the user’s channel selection, the corresponding channel is selected and sent to the TV set. The cable box also performs special signal processing, such as amplification and impedance matching, to ensure optimal signal quality for the TV.

• Satellite TV Signals: If the cable company receives satellite TV signals, they perform frequency translation to convert the signal to a format compatible with the cable system before transmitting it.