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How Do Fiber Optics and Cable Television Work?

by:TBT     2020-08-19
Fiber Optic cable and the old common (coaxial or RF) cable are two different cable system technologies that can be used to distribute various services to end users--homes. In general, they differ only in technical (electrical/communication) point of view. This is mainly important for the network operators because end users or viewers don't care about the technology, they are interested in services and TV channels.
There are few different ways that can be used to distribute common services like television channels via cable networks. Each has some advantages and disadvantages and needs different topology or network infrastructure.
Analog Television The first cable television networks were simply an extension of the broadcasts in the air. This was implemented by deploying ordinary antenna cable (but with lower losses) from the cable system headend to the homes. Because of the distances there were also many amplifiers at specific points to ensure required signal levels. The communication was exclusively one-way, but later most such cable networks were extended to allow bidirectional communication needed for access to the internet by using systems like DocSys.
This approach can be used with RF (coaxial) and fiber cables. Fiber optic cables are also used in some cases to distribute the old analog cable television. The advantage of optical network is because it can use available fibers in existing fiber optic cables and the cable losses are very low.
Digital Television Digital television in cable networks can be divided into two totally different ways of distribution. The first one is an equivalent to digital broadcasting and the other way mainly used in fiber optic networks is IP television.
Digital Cable Broadcasting This is equivalent to analog distribution over (RF) cable but with digital signal. The same technology (modulation) can be used as for terrestrial broadcasting but usually, there are more efficient systems that take into account specific properties of cable systems. One typical example is DVB-T system which is used in Europe for digital terrestrial video broadcasting but cables use similar DVB-C system.
IP Television This is the most popular digital television distribution used with fiber optic cable systems. It means distributing TV channels with the IP protocol which is the backbone of internet communications. Each TV channels is encoded with either MPEG-2 or MPEG-4 system and then distributed over fiber optical cable network to the homes. The advantages are enormous. The capacity for the number of channels is pretty high, all the channels can be encoded and distributed with very high quality, it is very easy to distribute HD channels, access to the internet is very simple because of the IP protocol and native technology.
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