DigiPoints Volume 2. Student Workbook. Module 1 Components of a Digital System

Transcription

1 Components of a Digital System Page 1.1 DigiPoints Volume 2 Module 1 Components of a Digital System Summary The content in this module includes an overview of the functional architecture of a digital cable system, the hardware components of the system, and organizations that recommend digital standards pertaining to digital cable systems. Module Objectives Upon successful completion of this module, the student will be able to: Compare analog cable systems to digital cable systems. Identify the two main areas to which digital technology is applied in cable systems. Identify the signal sources for media-related and services-related applications. Name the types and formats of signals digital cable systems carry, and how they are carried over different media. Name the three primary categories of hardware components. For a typical cable system, select hardware components required for digital video and high-speed data over cable applications and show where they would be installed. Name the components associated with telephony-based digital cable applications. Name some of the new skills required of employees in a digital cable system. Identify seven organizations responsible for setting digital standards applicable to the cable industry, and the digital standards for which each organization is responsible. Prerequisites Read, Chapter 1. As you complete this module, you should be filling in answers and definitions for the items found on the following pages.

2 Components of a Digital System Page 1.2 Exercise #1 This exercise will help you recall knowledge you gained in the first 12 learning modules of Digipoints, Volume 1. It is also intended to help you begin to place this knowledge in the context of your working world that is, the job tasks you are or will be performing in migrating from analog cable services to digital cable technology. Participate in this 20-minute exercise with your classmates by reviewing the functions performed in an analog cable system, and recalling digital technology that may be required for performing these functions in a digital cable system. 1. What are the main functions performed in an analog cable system? 2. What are the hardware components that perform these functions? 3. What digital technology can you recall that might appear in a digital cable system? 4. What signal sources can you think of that could be inputs to a digital system?

3 Components of a Digital System Page 1.3 Functional Architecture Take notes on these two pages as your instructor covers the topics in the Functional Architecture section of Module 1. Constructing meaningful notes helps you learn the information and can serve as a useful future reference. Two functional areas Media-related: Transport Access

4 Components of a Digital System Page 1.4 Services-related: Services processed from other sources include: Digital Video Telephony Data Services originating at the headend include: Interactive Video Insertion Services Government-mandated Services Operational Support Systems

5 Components of a Digital System Page 1.5 Hardware Components Sources of signals to a Digitization Center or a Digital Turnaround System include: Off-air feeds, terrestrial feeds, and local programming. Two functions of a Digitization Center: Signal digitization Access control

6 Components of a Digital System Page 1.6 The Headend performs as a service node in a digital network. Hardware components in the headend include: Broadband Switch Higher-layer protocol interfaces to external components Customer-side access physical interfaces

7 Components of a Digital System Page 1.7 Transport-side physical interfaces Network management system Services-related Components: Emergency Alert System (EAS)

8 Components of a Digital System Page 1.8 Telephony-related Components: Telephony Switch Host Digital Terminal Digital Cross-connect System (DCS) Digital Multiplexer

9 Components of a Digital System Page 1.9 Video-related Components: Integrated Receiver/Transcoder Frequency Upconverter Digital Multiplexer Digital Modulator

10 Components of a Digital System Page 1.10 Data-related Components: Cable Modem Termination System Router Dial Access Server Security Management Interface Operations Support System Interface

11 Components of a Digital System Page 1.11 Two applications of Data over Cable: Institutional Networks (I-NET) High Speed Data Service via Cable Modem Operations, Maintenance and Administration System Billing Systems and Interfaces

12 Components of a Digital System Page 1.12 Take a 10-minute break! Take this time to stand up and stretch, take some deep breaths, and freshen yourself with a beverage or a chat with your fellow DigiPoints students. Near the end of your break time, you may want to spend some time reviewing the notes you took in the previous pages. Make sure your notes are complete and that you will be able to understand them when you refer to them a month or a year from now. Also, reviewing the previous pages will help you perform better in Exercise #2, scheduled shortly after your break time.

13 Components of a Digital System Page 1.13 Production Facility: Video Server Digital Mixers Signal Routing and Distribution Systems Video Editors Ad Insertion Equipment

14 Components of a Digital System Page 1.14 Exercise #2 In Exercise #2, your instructor will divide your class into two Small Groups and assign a leader to each one. Your Small Group Leader is responsible for keeping the group on task, assuring participation from all members of the group, recording the information generated by the Small Group, and for presenting the information to the other Small Group at the end of the Exercise. (However, your Small Group Leader has the choice of assigning this final task to another member of your Small Group.) Try to complete the exercise without looking at your notes. This will help you retain the information that you heard in the first half of the module. Group 1: Based on the information just presented, construct a digital cable system that provides its customers with data over cable applications. Identify all of the hardware components necessary to provide data over cable to customers. Show the physical locations in which the hardware components are located. As your group completed this exercise, what information presented in this module so far was confusing to members?

15 Components of a Digital System Page 1.15 Group 2: Based on the information just presented, construct a digital cable system that provides its customers with video applications. Identify all of the hardware components necessary to provide digital video to customers. Show the physical locations in which the hardware components are located. As your group completed this exercise, what information presented in this module so far was confusing to members?

16 Components of a Digital System Page 1.16 Hardware Components Fiber Node Customer Premises Network Interface Unit (NIU) Information Appliances Set-top Boxes Digital TV Computer Cable Modem

17 Components of a Digital System Page 1.17 Telephony Modem Alarm Systems, Meter Reading, and Control Telephone Station Sets Trunk Plant Feeder Plant (also known as Distribution Systems) Drop System Network Administration

18 Components of a Digital System Page 1.18 Standards Organizations Digital Grand Alliance Digital Audio-Visual Council (DAVIC) Multimedia Cable Network Systems (MCNS) Society of Cable Telecommunications Engineers (SCTE) American National Standards Institute (ANSI) Institute of Electrical and Electronics Engineers (IEEE)

19 Components of a Digital System Page 1.19 Testing Your Knowledge Your Instructor has the answers to these questions in the Appendix to Module 1 of the DigiPoints, Volume1, Leader Guide. 1. What are the two sides to media-related digital functions, and to what do they pertain? 2. What is a reason an operator might use a centralized digitization system? What might be a disadvantage of using this type of system for digitization of program content? 3. What are two functions of the digitization center? 4. What are the three functions of a local telephony switch? 5. What is contained in the out-of-band control data stream in a downlinked satellite video signal that originates in a digitization center?

20 Components of a Digital System Page What is the advantage of terrestrial transport over satellite distribution from a digitization center? 7. What are the major functions of a Network Operations Center (NOC)? 8. What is the name of the MCNS standards document?

21 Components of a Digital System Page 1.21 Glossary AC-3 Dolby - Digital audio standard Access Requirements - Attributes a receiver must have to process a signal Access Rights - The set of access requirements possessed by a receiver ATSC - Advanced Television Systems Committee; a United States digital television standards body Baseband - The audio and video signals in the form they are created by the source device BORSCHT - Acronym for the functions a telephony switch must provide for a line. It stands for Battery, Overvoltage protection, Ringing, Supervision, Codec, Hybrid, and Test. Class 5 Telephony Switch - Another name for a telephony switch that provides local telephone service Digital Turnaround System - System that digitizes signals at a central location and distributes them to remote headends DVB - Digital Video Broadcasting group; a European video standards organization GR Bellcore standard that specifies the interface between a digital telephony switch and a Host Digital Terminal HITS - Comcast's implementation of a digitization center using satellite distribution for transport of the digitized signal I-NET - Institutional Network Information Appliance - Generic name for digital equipment at a customer premise location

22 Components of a Digital System Page 1.22 NIU - Network Interface Unit; the demarcation point between customer-maintained communications equipment and wiring and service provider-maintained equipment and wiring; also a name for the card where the input signal terminates at the digital set-top box NOC - Network Operations Center; centralized monitoring and maintenance location for a telecommunications network Smart Card - Removable card with electronic circuitry that stores information TAC - Technical Assistance Center TR Bellcore specification for less functional interfaces between local telephony switches and a Host Digital Terminal than those specified by GR-303 TR Previous designation for GR-303 Upconverter - Equipment that converts IF signals to RF signals without changing the information content