RF headends are electronic control centers, generally located at the antenna site of a system, which include the antenna, preamplifiers, frequency converters, demodulators and other related equipment. A cable access television (CATV) network or community access television (CATV) system allows cable TV to be distributed to a wide network of viewers. RF headends are considered the control centers for CATV networks. RF headends accept incoming video signals from RF carriers and amplify, convert, and process the individual signals before distributing a combined single to each cable television viewer. In RF headends, a large number of wires connect the various components of the complete RF head end system. RF headends are generally located in the same place as the cable modem termination system (CMTS). The CMTS connects thousands of cable modems over a network that can stretch to over 100 km with potential data rates up to 50 Mbits/sec. The CMTS also connects to the Internet and other media sources, sending and receiving user packets.
RF headends receive signals from satellites and other sources. Upon receipt, frequency division multiplexing is used to combine signals from broadcast processors, satellites, and local systems channels into a single feed. The combining process simply connects the different signals and unifies them into one output that contains all input signals. After combining, the RF headends then transmit the new, unified signal from the RF headend distribution center to local nodes over fiber optic cable. Most CATV networks now use a hybrid fiber coaxial (HFC) cable for distribution. From this point, the signal is again converted to a coaxial cable, which will transmit the signal to individual cable subscribers.
Suppliers of RF headends are located across the United States and around the world. They meet a variety of regulatory requirements and quality standards. In the United States, the Federal Communications Commission (FCC) is the governing regulatory agency. In Europe, RF head end products that meet European Union (EU) directives bear the CE Mark.