...A digital signal is a physical signal that is a representation of a sequence of discrete values (a quantified discrete-time signal), for example of an arbitrary bit stream, or of a digitized (sampled and analog-to-digital converted) analog signal. The term digital signal can refer to either of the following: any continuous-time waveform signal used in digital communication, representing a bit stream or other sequence of discrete values a pulse train signal that switches between a discrete number of voltage levels or levels of light intensity, also known as a line coded signal or baseband transmission, for example a signal found in digital electronics or in serial communications, or a pulse code modulation (PCM) representation of a digitized analog signal. A signal that is generated by means of a digital modulation method (digital passband transmission), to be transferred between modems, is in the first case considered as a digital signal, and in the second case as converted to an analog signal. ======================== An analog or analogue signal is any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. For example, in an analog audio signal, the instantaneous voltage of the signal varies continuously with the pressure of the sound waves. It differs from a digital signal, in which a continuous quantity is represented by a discrete function which...
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...Part-A End-of-Chapter-4 Questions (match questions, overlook number mismatch) 1. How does analog data differ from digital data? Computers produce digital data that are binary, either on or off. In contrast, telephones produce analog data whose electrical signals are shaped like the sound waves they transfer. Analog data are signals that vary continuously within a range of values (e.g., temperature is analog). 1. Clearly explain the differences between analog data, analog transmission, digital data, and digital transmission. Data can be transmitted through a circuit in the same form they are produced. Most computers, for example, transmit their data through digital circuits to printers and other attached devices. Likewise, analog voice data can be transmitted through telephone networks in analog form. In general, networks designed primarily to transmit digital computer data tend to use digital transmission, and networks designed primarily to transmit analog voice data tend to use analog transmission (at least for some parts of the transmission). 4. How does baseband differ from broadband? Baseband is the digital transmission of binary electrical pulses. Broadband is the analog waveform used for transmission. 4. What is coding? Coding is the representation of one set of symbols by another set of symbols. In data communications, this coding is a specific arrangement of binary 0s and 1s used to represent letters, numbers, and other symbols that...
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...TELECOMMUNICATIONS Telecommunication is communication at a distance by technological means, particularly through electrical signals or electromagnetic waves. Due to the many different technologies involved, the word is often used in a plural form, as telecommunications. Early telecommunication technologies included visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs. Other examples of pre-modern telecommunications include audio messages such as coded drumbeats, lung-blown horns, and loud whistles. Electrical and electromagnetic telecommunication technologies include telegraph, telephone, and teleprinter, networks, radio, microwave transmission, fiber optics, communications satellites and the Internet. A revolution in wireless telecommunications began in the 1900s with pioneering developments in radio communications by Guglielmo Marconi. Marconi won the Nobel Prize in Physics in 1909 for his efforts. Other highly notable pioneering inventors and developers in the field of electrical and electronic telecommunications include Charles Wheatstone and Samuel Morse (telegraph), Alexander Graham Bell (telephone), Edwin Armstrong, and Lee de Forest (radio), as well as John Logie Baird and Philo Farnsworth (television). The world's effective capacity to exchange information through two-way telecommunication networks grew from 281 petabytes of (optimally compressed) information in 1986, to 471 petabytes in 1993, to 2.2 (optimally...
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...department(HOD) who also contributed in his own way and also to school for bringing out the seminar format which guided us well and made our work easier. And to our most beloved parents, guardians which God used in providing the financial resources for us. We say a very big thank you to them all and pray that God bless us all. THANKS CHAPTER ONE INTRODUCTION DEFINITIONS OF SOME TERMS A DIGITAL SYSTEM is a data technology that uses discrete (discontinuous) values. By contrast, non-digital (or analog) systems represent information using a continuous function. Although digital representations are discrete, the information represented can be either discrete, such as numbers and letters or continuous, such as sounds, images, and other measurements. The word digital comes from the same source as the words digit and digitus (the Latin word for finger), as fingers are used for discrete counting. It is most commonly used in computing and electronics, especially where real-world information is converted to binary numeric form as in digital audio and digital photography. DIGITAL TRANSMISSION SYSTEM is a transmission system in which (a)...
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...Telephone and Data Networks The corporate main office is in Ohio. The office at this location uses Avaya Digital Phone System and is connected to a Cisco 10 MB Hub. All equipments in this location get access to the Avaya Digital Phone System through the 10 MB Hub. The plant at the Ohio location has set up different workstations; each workstation has a wireless bar code, scanner, shipper, and telephone. The office in California is currently using Private Branch eXchange System PBX system as communication system, routing incoming calls to the appropriate extension in the office. The California office uses The Plain Old Telephone Service POTS, with and intercom. The current POTS does not have caller ID nor does Voice Mail. All the connection phones in California’s office are connected to the PBX. The plant in California uses a different phone system than the California office. The California Plant uses the Nortel Digital Phone System. The phone system is Voice-over-IP, which is VOIP; basically this phone system is connected to an Ethernet connection. The office in Missouri is currently using Avaya Digital Phone System; this system is connected to a Cisco 10MB Hub. The Avaya Digital Phone System connects all the phones and faxes in the location. The plant at the Missouri location has set up different workstations. Each workstation has a wireless bar code scanner, printer, shipper, and a telephone. All the workstations are connected to the Cisco 10 MB Hub. The office at...
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...Annual Report 2005 - 2006 BANGLADESH TELEGRAPH & TELEPHONE BOARD Chairman's Message Advances in telecommunication & information technology (ICT) have done more than anything else to drive the last decade's economic boom and the integration of markets around the planet. Since telecommunications play an important role in the development of ICT as well as socio-economic condition of a country, development of telecommunication is essential. Bangladesh T & T Board (BTTB), the only public sector telephone service provider, is doing the best with its limited resources to provide most advanced telecommunication services to its valuable subscribers. BTTB has a firm policy to digitalize the complete network as soon as possible. Digitalization of BTTB network started back in the year 1983 and over the past few years, the installation of digital equipment has increased considerably. In the mean time, all the district headquarters & 377 upazilla's have been equipped with digital exchanges. Remaining upazillas will have digital exchange very soon. In the age of information technology (IT), a robust and efficient national transmission system is required to support telecommunication and data communications, as well as the IT activities of a country. With this end in view BTT B is gradually installing and expanding Optical Fiber network and SDH microwave links throughout the country. Initiative...
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...Chapter 8 Telecommunications and Networks Teaching Objectives Students should be able to answer the following questions: 1. What technologies are used in telecommunications systems? 2. What telecommunications transmission media should our organization use? 3. How should our organization design its networks? 4. What alternative network services are available to our organization? 5. What telecommunications applications can be used for electronic business and electronic commerce? Key Terms The following alphabetical list identifies the key terms discussed in this chapter. The page number for each key term is provided. |802.11b (Wi-Fi), 269 |Microwave, 263 | |Analog signal, 261 |Mobile data networks, 264 | |Asynchronous transfer mode (ATM), 271 |Modem, 261 | |Backbone, 262 |Multiplexer, 266 | |Bandwidth, 265 |Network interface card (NIC), 269 | |Baud, 265 |Network operating system (NOS), 269 | |Bluetooth, 270...
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...NT1310:Week 1 Telecommunications By: Kenneth Martin You are an IT Network Specialist and are required to develop the design of the company’s telephone system for its new building which will begin construction in a few months. In order to get a background which will help when developing the new system, your supervisor asked you to research the current Plain Old Telephone Service (POTS) currently used by the company. You must research the system components and report back to your supervisor , the Telecommunications Manager, within a week. 1. Describe a local land line phone system based on the following Landline Telephone Components: a. Local Loop a local loop is the wired connection from a telephone company's central office in a locality to its customers' telephones at homes and businesses. This connection is usually on a pair of copper wires called twisted pair. The system was originally designed for voice transmission only using analog transmission technology on a single voice channel. Today, your computer's modem makes the conversion between analog signals and digital signals. With Integrated Services Digital Network (ISDN) or Digital Subscriber Line (DSL), the local loop can carry digital signals directly and at a much higher bandwidth than they do for voice only. b. Central Office In telephone communication in the United States, a central office (CO) is an office in a locality to which subscriber home and business lines are connected on what is called a local...
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...Protocol (VoIP). If I had to put this in plain terms, this technology allows voice traffic to be transmitted over the Internet. VoIP is a new application of Internet Protocols (IP) that enables the conversion of voice communications into data packets and then these packets are transmitted via an IP network such as the Internet. “VoIP services convert your voice into a digital signal that travels over the Internet”. (fcc.gov) Similar to using your analog phone system and going through a Public Switched Telephone Network (PSTN), now you will be using a digital phone and going through the Internet. All you need to get the ball rolling and to be part of this new trend is a decent Internet connection at home and you could say goodbye to that plain old analog telephone line forever. Most cable companies are offering service bundles that include cable television, Internet access and telephone services. These companies are transitioning from the telephone analog system to the VoIP systems. A lot of costumers are switching over to VoIP for the simple reason of saving money. VoIP services usually offer better rates for local and international calls compare to the traditional telephone company rates. VoIP is the technology that makes it possible to have a telephone conversation over the Internet or a dedicated Internet Protocol network instead of dedicated voice transmission lines. This allows the elimination of circuit switching and the associated...
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...1.2 SYSTEMS Systems and some of the subsystems that Telematics provides are as follows. 1.2.1 INFORMATION & COMMUNICATION TECHNOLOGY SYSTEMS Information & Communication Technology (ICT) refers to all technologies used to handle and provide access to information through telecommunications. It mainly focuses on communication technologies. This includes the Internet, wireless networks, cell phones, and other communication mediums. 1.2.1.1 STRUCTURED CABLING SYSTEMS A structured cabling is the wiring network of a building or group of building’s telecommunications cabling infrastructure that carries all the data, voice, security, Voice over Internet Protocol, Power over Ethernet, and even wireless connections. It includes cabling, connecting...
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...(WANs) Objectives By the end of this lesson, you will be able to: Describe the characteristics and functions of wide area networks (WANs). Define basic signaling and transmission terminology, including analog and digital signals, Digital Signal Level Zero (DS0), broadband, baseband, multiplexing, and Digital Signal Hierarchy (DSH). Distinguish between circuit switching and packet switching, and identify various circuit-switching and packet-switching technologies. Describe the characteristics and performance of dial-up connections, including POTS and Integrated Services Digital Network (ISDN). Describe the characteristics and performance of direct connections, including leased T-carrier and E-carrier lines, cable Internet, Digital Subscriber Line (DSL), LAN connections, and fiber to the x (FTTx). Describe the characteristics and functions of Synchronous Optical Network (SONET). Describe the characteristics and functions of Asynchronous Transfer Mode (ATM). 2-2 Local Area Networks (LANs) Pre-Assessment Questions 1. Which of the following is faster than T1? a. b. c. d. 2. E1 ISDN BRI DS0 DS1 Which type of transmission uses a single channel? a. b. c. d. Broadband Digital Subscriber Line (DSL) Baseband Cable modem 3. How are digital signals measured? © 2012 CertPRESS, a division of Certification Partners, LLC — All Rights Reserved. Version 7.0 Lesson 2: Wide Area Networks (WANs) 2-3 Introduction to Wide Area Networks (WANs) wide...
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...PART ONE Requirements P art One defines the needs for information communications in the business environment. It discusses the ways in which various forms of information are used and the need for interconnection and networking facilities. ROAD MAP FOR PART ONE Chapter 2 Business Information The requirements for data communications and networking facilities in an organization are driven by the nature and volume of information that is handled. Chapter 2 provides an overview of the four basic categories of information used in any organization: audio, data, image, and video. The chapter discusses some of the salient characteristics of each type and looks at their networking implications. Chapter 3 Distributed Data Processing Chapter 3 describes the nature and role of distributed data processing (DDP) in an organization. Virtually all business information systems organizations are distributed, and the networking and communications requirements are driven by the way in which data and applications are distributed. ISBN 0-558-69515-9 31 Business Data Communications, Sixth Edition, by William Stallings. Published by Prentice Hall. Copyright © 2009 by Pearson Education, Inc. CHAPTER BUSINESS INFORMATION 2.1 2.2 2.3 Audio Networking Implications Data Networking Implications Image Image Representation Image and Document Formats Networking Implications Video Digital Video Networking Implications Performance Measures Response Time Throughput Summary Recommended...
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...the same circuit. This means that each must share the circuit with the others, much like a party line in telephone communication. The disadvantage is that only one computer can use the circuit at a time. When computer is sending or receiving data, all others must wait. The advantage of multipoint circuits is that they reduce the amount of cable required and typically use the available communication circuit more efficiently. Multipoint configurations are cheaper than point-to-point configurations. Point-to-point configuration is so named because it goes from one point to another (e.g., one computer to another). These are also called as dedicated circuits because they are dedicated to the use of these two computers. This type of configuration is used when the computers generate enough data to fill the capacity of the communication circuit. This can get very expensive, particularly if there is some distance between the computers. 3. Describe Three types of guided media. Guided media are those in which the message flows through a physical media such as a twisted pair wire, coaxial cable, or fiber-optic cable. a. Twisted pair wire is most commonly used. It is a pair of wires used in standard telephone wiring. They are twisted to reduce interference caused by the other twisted pairs in the same cable bundle. Twisted-pair wires go from homes and offices to the telephone company end office. b. Coaxial cable is a type of guided media that is quickly disappearing. It is an...
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...IIIrd yr. CONTENTS 1. Introduction 2. Broadband Technologies I. Multilinking Modems II. ISDN III. T-1/DS1 IV. Wired Ethernet V. Rural Broadband VI. Satellite Internet VII. Mobile Broadband VIII. Power line Communication IX. DSL X. Wireless ISP 3. Broadband Services I. In Telecommunication System II. In Data Communication 4. Bibliography 5. Appendix Introduction Broadband Internet access, often shortened to just broadband, is a high data rate Internet access—typically contrasted with dial-up access using a 56k modem. Dial-up modems are limited to a bitrate of less than 56 kbit/s (kilobits per second) and require the full use of a telephone line—whereas broadband technologies supply more than double this rate and generally without disrupting telephone use. Although various minimum bandwidths have been used in definitions of broadband, ranging up from 64 kbit/s up to 2.0 Mbit/s, the 2006 OECD report is typical by defining broadband as having download data transfer rates equal to or faster than 256 kbit/s, while the United States (US) Federal Communications Commission (FCC) as of 2009, defines "Basic Broadband" as data transmission speeds exceeding 768 kilobits per second (Kbps), or 768,000 bits per second, in at least one direction: downstream (from the Internet to the user’s computer) or upstream (from the user’s computer to the Internet). The trend...
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...Chapter 3: Physical Layer Chapter Outline INTRODUCTION CIRCUITS Circuit Configuration Data Flow Communication Media Multiplexing How DSL Transmits Data COMMUNICATION MEDIA Guided Media Wireless Media Media Selection DIGITAL TRANSMISSION OF DIGITAL DATA Coding Transmission Modes Digital Transmission How Ethernet Transmits Data ANALOG TRANSMISSION OF DIGITAL DATA Modulation Capacity of a Voice Circuit How Modems Transmit Data DIGITAL TRANSMISSION OF ANALOG DATA Translating from Analog to Digital How Telephones Transmit Voice Data How Instant Messenger Transmits Voice Data VoIP IMPLICATIONS FOR MANAGEMENT SUMMARY Teaching Notes Generally preconceptions about what analog and digital transmission are vary greatly among undergraduate students. For this reason it is necessary to spend at least about 3-4 hours covering this chapter. Make sure at first that the students understand the dual characteristic state of what constitutes a circuit- the concepts of logical and physical. Circuits are probably the most important aspect of comprehending the physical layer. A circuit can be viewed and generally is viewed as a wire or a cable. This is the physical aspect of the circuit. There is also a logical aspect of a circuit. It is not just how long, wide or what type of cable; it is also what it is that propagates through the cable. When I discuss circuits and media, I try to remember to hand around twisted pair...
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