N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 10 - CATV Systems and Technologies                                                                               Slide 1 of 45                                                                                                    ________________

Objectives:

This module provides an introduction to CATV communications, its underlying technological trends, and the associated standards. Communications systems for homes, schools and businesses historically have been designed with a specific application in mind. Telephone networks were built to provide telephone services whereas cable television networks were built to provide television service. Both systems used an analogue technique to transmit the information over the networks.

Early cable television in the U.S. was introduced in the 1950s. At that time the television industry provided broadcast signals only to the most economically viable metropolitan areas. For regions that had poor TV reception, either because of obstructions or because of being a long distance from signal transmitters, cable television provided a workable solution. The cable television operators constructed large antennae on high ground (hill tops) for improved TV reception, and used coaxial cable to carry TV signals from the antenna to the local community. That is where acronym CATV came from which means Community Antenna Television. The CATV systems were designed for broadcasting TV signals. Traditional CATV systems include: headend, trunks, feeder cables, drop cables and terminal equipment (TV).

Headend 
The headend is the center of CATV activity. It receives signals from satellite, microwave, and local TV station broadcasts. Locally produced and prerecorded programs are added for broadcasting. The headend is responsible to receive, process, combine, and assign a channel frequency to all signals destined for cable distribution.

Trunks 
A number of trunks carry the signals from the headend to a series of distribution points. Amplifiers are required to maintain the adequate strength of the TV signal over long distances.

Feeder Cables 

Drop Cables 

Terminal Equipment
Terminal equipment (TV, Set-top box, VCR, Splitters, Cable modem) is connected to the drop cable inside a home or business.

The late 1980s marked the time where it made good business sense to begin replacing the coaxial cable distribution plant with optical fiber cable. Fiber carried a larger bandwidth for longer distances with fewer amplifiers that translated into lower maintenance costs and better signal quality. Fiber optics also facilitated a larger broadcast spectrum and bi-directional communications. A current state-of-the-art cable architecture is a hybrid fiber/coax (HFC) combination. Trunk cables are upgraded to optical fiber without replacing feeder and drop cables. Next-generation cable infrastructure is envisioned to offer multi-media services (voice, data, audio and video) tailored to the individual neighbourhood.

Multiple Systems Operators (MSO) networks have evolved from a one-way distribution network to a two-way interactive network. The demand for multi-media services have evolved the next-generation networks to include optical capabilities. Optical transmission is more capable of supporting higher bandwidth rates with high reliability, reaching extended distances, and being immune to radio frequency interference. Most operator systems have a multitude of services carrying video, data and telephony.

ATM and SONET technologies were introduced into cable networks to support multi-media applications. Although SONET is very reliable, its inherent cost and the additional equipment required for protocol conversions make such a network very expensive and thus usage has been limited to the core of the network. SONET also presented scaling challenges in supporting the bandwidth growth of applications such as Video-On-Demand, Internet access, and PacketCable-based voice services. The solution to avoid complexity, scalability and economic challenges is Wave Division Multiplexing technology. WDM technology provides the capability to transport different services in their native format.

MSO networks are constantly evolving and the need for multi-service solutions is greater than ever.

This module will cover:

1.0   CATV systems concepts

2.0   CATV network architecture

3.0   CATV network components: Headend, Trunks, Feeder Cables, Drop Cables and Terminal equipment

4.0   CATV systems

5.0   Analogue and digital CATV systems architectures

6.0   Hybrid Fiber-Coax (HFC), Fiber-To-The-Curb (FTTC), Fiber-To-The-Home (FTTH) networks architectures 

7.0   Next-Generation CATV network architecture

8.0   CATV services

9.0  CableLab initiatives (High-speed data-over-cable, telephony over cable)

10.0  Cable Modem and Set-Top Box

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