Digital Head
cable head-end
Millions of people watch cable TV but no one knows what exactly it is. How it reaches to your home it is not just a cable which gives you the complete data or you can say the programs that you are watching. Behind this, a technology is used which is called as cable head-end. Before discussion you have to know what head-end is. Cable head-end is the master distribution centre of a CATV system by which incoming television signals from video sources are received, selected, amplified and re-modulated on to TV channels for transmission down the CATV system. Space-tech provides you the complete head-end solution for your cable TV.
.PROCEDURE
Ø The incoming signals for head-end system include satellite receivers, off-air receivers and other types of transmission links. In order to minimize losses in coaxial cable that carry dish antenna signal to control room, the signals are first translated to a lower frequency range. This is done by LNB (low noise block converter). The signal from the LNB is delivered to a signal splitter that divides the signals. The signal splitter commonly called a “POWER DIVIDER” which splits the signal into number of signals you needed. The signals are received and then processed by decoders. In head-end integrated receiver decoder (IRD) is used to pick up the radio-frequency (RF) signals and convert digital information in it.
Ø So, that the signals can be stored in the CATV network. After the signals stored, the signals are modulated for every channel one modulator is used every modulator has different frequency, but in case of digital head-end system QAM modulator is used, after modulation the signals are fed to combiner the combiner converts multiple input signals into one output signal. When combining of signals is done the weak signals are amplified by using an RF amplifier.
Ø After that the signals can be sent to distribution system through cable. In homes set-top-box is used to receive the signals in case of digital head-end, the STB is connected to your TV set through which you can watch the signals in form of channels or you can say programs on your TV screen.
Ø For digital cable TV a CAS (conditional access system) system is also used for protection of the data
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