...Chapter 1: INTRODUCTION Almost all machines in industries are operated using electrical motors. Among them most of the motors are DC motors. DC series motor is specially used for traction, electric locomotive, trolley systems, crane and conveyer belt. All these works require frequent speed control for the preparation of job. We could gear the motor for the proper speed, but this is usually beyond scope of what we can accomplish in the basement workshop or we could measure the current that the motor draws and determine a series resistor value according to ohms law to insert to “drop” the motor supply voltage and slow the motor down. The problem with this approach is that if load on the motor increases, the motors operating current also increases, creating a larger voltage drop across that series resistor and supplying less voltage to the motor terminals when it is needed the most. This “vicious circle” usually results in the motor stalling at high load conditions. So what we need is a controller that will give the motor a kick of supply voltage for a variable amount of time to achieve the proper speed without the series dropping effect. A PWM (Pulse width modulation) wave can be used to control the speed of the motor. CHAPTER 2 WIRELESS COMMUNICATIONS Wireless communication is the transfer of information over distance without the use of electrical conductors or “wire”. The distances involved maybe short (a few meters as in television remote control) or long (thousands or...
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...his time and schedule just to make sure that the best is been brought out from this group and also to the group leader who consistently made every effort and spent sleepless night ensuring that the seminar topic research was a worthwhile and fulfilling one, also to us been the group members who contributed to the success of the research topic. We also want to thank the head of engineering 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...
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...If A and B are two bits arriving at the relay node, with the use of network coding the relay node can add the bits together e.g. mixing A and B here and transmitting A + B to achieve the multicast capacity of 2 bits per second because here transmission of 2 bits (A+B) is taking place Network coding offers definitely an improvement over traditional routing in which the link transmits either A or B instead both bits together. The major difference between communication performed with and without network coding in a wireless system is shown in Figure 1.7. More specifically, Figures 7(a) and 7(b) depict the transmission of packet b1 from A to B and packet b2 from B to A using relay C- when the range of and A and B is r. Figure 7(c) demonstrates that the relay C needs only one extra step to broadcast the linear combination of packets b1 and b2 as opposed to a conventional system which would require two extra steps, i.e, one step to transmit b1 and one step to send b2. Figure 1.7 Wireless communication without network coding (b) and with network coding (c) To conclude, we see that network coding in the previous example requires 3 time slots. Physical network coding allows A and B to transmit simultaneously reducing the total number of time slots to 2. This is a great idea to increase data transfer rates by minimizing the time...
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...Australia • Brazil • Japan • Korea • Mexico • Singapore • Spain • United Kingdom • United States SEVENTH EDITION Data Communications and Computer Networks A Business User’s Approach Curt M. White DePaul University Australia • Brazil • Japan • Korea • Mexico • Singapore • Spain • United Kingdom • United States Data Communications and Computer Networks: A Business User’s Approach, Seventh Edition Curt M. White Editor-In-Chief: Joe Sabatino Senior Acquisitions Editor: Charles McCormick, Jr. Senior Product Manager: Kate Mason Editorial Assistant: Courtney Bavaro Marketing Director: Keri Witman Marketing Manager: Adam Marsh Senior Marketing Communications Manager: Libby Shipp Marketing Coordinator: Suellen Ruttkay Media Editor: Chris Valentine Art and Cover Direction, Production Management, and Composition: PreMediaGlobal Cover Credit: © Masterfile Royalty Free Manufacturing Coordinator: Julio Esperas © 2013 Course Technology, Cengage Learning ALL RIGHTS RESERVED. No part of this work covered by the copyright herein may be reproduced, transmitted, stored or used in any form or by any means—graphic, electronic, or mechanical, including but not limited to photocopying, recording, scanning, digitizing, taping, Web distribution, information networks, or information storage and retrieval systems, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act—without the prior written permission of the publisher. For product information and technology assistance...
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...represented in binary as 1111010100. Upon right shifting this value we get 11110101 which makes 245 in decimal. On the receiving end, upon multiplying by 4, we get 980 which gets plotted. This technique produces a maximum error of +/-3 which is negligible. The ADC module converts the incoming values into a digital value and saves it in a dedicated register ADC10MEM. The value of this register is first copied into UCA0TXBUF (After being converted into 8-bit) in order to transmit it to the PC. It is kept in mind to clear the UCA0TXBUF and the Interrupt flag register each time after transmitting the value in order to ensure proper transmission of data. 6.4.2 TALKING TO PC 6.4.2.1 COM PORT A COM port, also...
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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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...1. What does the data link layer do? The data link layer accepts messages from the network layer and controls the hardware that actually transmits them. It is responsible for getting a message from one computer to another without having an errors. It also accepts streams of bits from the physical layer and organizes them into messages that it passes to the network layer (Fitzgerald, 2009). 10. Describe four types of noise. Which is likely to pose the greatest problem to network managers? Line noise, which is all known as distortion, can cause data communication errors. Noise affects the line by things such as equipment or natural disturbances and it lowers the performance of the communication circuit. White noise is similar to background static on a radio or telephone which is caused by the thermal agitation of electrons and therefore is inescapable. Even if the equipment is was perfect and the wires were perfectly insulated from any and all external interference there you will still hear white noise. White noise doesn’t become a problem unless the noise is so strong that it affects the transmission (Fitzgerald, 2009). Impulse noise is the primary source of errors in data communications. Some of the sources of impulse noise are voltage changes in adjacent lines, lightning flashes during a thunderstorm, fluorescent lights, and poor connections within the circuits (Fitzgerald, 2009). Intermodulation noise is a special type of cross-talk and occurs when the...
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...Constance Smith Chapter 4: Fiber- Optic Cable NT1110, Friday Class 17 of January Exercise: 4.1.2 The light in an SMF cable travels down the center of the fiber parallel to the direction of the fiber in a single path. Can this type of cable be used to transmit and receive bits simultaneously, or does it require one fiber for transmitting and one for receiving? Justify your answer using your textbook and internet research. Answer: If you've run any cabling at all, you know that the typical distance limitation for UTP cabling with typical Ethernet -- up to 1 Gbps anyway -- is 100 meters. However, if you're running cabling for some other purposes, such as 10 Gbps or 40 Gbps, be mindful of the distance limitations associated with the type of cabling you intend to use. For example, if you intend to run 10 Gbps for up to 100 meters over twisted pair cabling, you need to use Category 6A or better cabling. Exercise: 4.2.3 MMF distance can still far exceed copper cable, but MMF cannot match the distance available from the more expensive SMF. What is the reason for the distance limitation with the use of MMF? Answer: Multi-mode fiber (MMF) uses a much bigger core and usually uses a longer wavelength of light. Because of this, the optics used in MMF has a higher capability to gather light from the laser. Single-mode fiber (SMF) has much tighter tolerances for optics used. The core is smaller and the laser wavelength is narrower. This means that SMF has the capability for...
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...5. Standards 1.6. Further Reading 1.7. Summary 1.8. Exercises 2. The Physical Layer 2.1. Equipment 2.1.1. Equipment Types 2.1.2. Connection Types 2.2. Transmission 2.2.1. Signal Types 2.2.2. Modulation 2.2.3. Digitization 2.2.4. Synchronization 2.2.5. Transmission Media 2.3. Multiplexing 2.3.1. Space Division Multiplexing (SDM) vi Communication Networks 6 10 1 2 2 4 7 7 8 9 9 10 10 11 11 12 12 13 14 15 16 18 19 19 19 20 20 21 22 23 24 27 28 Copyright © 2005 PragSoft 2.3.2. Frequency Division Multiplexing (FDM) 2.3.3. Time Division Multiplexing (TDM) 2.3.4. Concentration 2.4. Physical Layer Standards 2.4.1. RS-232 2.4.2. CCITT X.21 2.5. Further Reading 2.6. Summary 2.7. Exercises 3. The Data Link Layer 3.1 Link Protocol Types 3.1.1. Synchronous Protocols 3.1.2. Asynchronous Protocols 3.1.3. Master-Slave Protocols 3.1.4. Peer-to-Peer Protocols 3.2. Link Protocol Functions 3.2.1. Acknowledgments 3.2.2. Timers 3.2.3. Error Checking 3.2.4. Retransmission 3.2.5. Flow Control 3.3. Sliding Window Protocol 3.4. Data Link Layer Standards 3.4.1. BSC 3.4.2. HDLC 3.5. Further Reading 3.6. Summary 3.7. Exercises 4. The Network Layer 4.1. Network Services 4.2. Switching Methods 4.2.1. Circuit Switching 4.2.2. Packet Switching 4.3. Packet Handling 4.3.1. Packet Structure 4.3.2. Routing 4.3.3. Congestion Control 4.3.4. Error Handling 4.4. Internetworking 4.4.1. Network Sublayers...
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...Pam Duschek NT1210 8-18-2015 Chapter 2 Review Activities 1) D 2) B 3) B and E 4) C and E 5) A 6) D 7) C 8) C 9) A, C and D 10) C and D 11) A 12) C and D 13) B 14) C 15) A and D 16) D 17) D 18) D 19) A 20) B Define Key Terms Computer Networking: A group of computers sharing data. Computer Network: A LAN (local area network) that connects computers in a house, at school or at work. Application: A software program that runs on any computer / device that enables the user to perform specific tasks. Email: A system for sending and receiving messages. Voice call: A telephone call. Video Frame: A video frame is a rectangle of individual points of light of the video image, as frozen in time. Web Server: Stores information (text, graphics, video, and audio) that the user wants to see and hear, collecting that information into web pages. Web Browser: Software that allows a user to get and display a copy of a web page from a web server. Web Address: Identifies the specific web page that the user wants to display. Web Page: Identified by the name after the / in the URL. Protocol: A set of standards (rules) that defines how software on different devices communicate. HTTP: A standard used by web servers and browsers to define the format of web addresses. Enterprise Network: A network owned and operated by a...
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...William Wragg Mr. Thomas Fortenberry IST 113471 17 October 2014 Chapter 7 Exercises 1. What is the definition of a local area network? a. A communication network that interconnects a variety of data communicating devices within a small geographic area and broadcasts data at high data transfer rates with very low error rates. 2. List the primary activities and application areas of local area network. b. File server, print server, connections to other networks. 3. List the advantages and disadvantages of local area networks. c. The advantages are sharing of files and devices, and intercommunication. d. The disadvantages are maintenance, complexity, and costs. 4. What are the basic layouts of local area networks? List two advantages that each layout has over the others. e. Buses advantages are the use of low-noise coaxial cable, and inexpensive taps. f. Star-wired buses are simple to interconnect, have easy to add components, and are most popular. g. Star-wired rings are simple to interconnect and have easy to add components. 5. What is meant by a passive device? h. A signal that enters is neither amplified nor regenerated. The signal is simply passed on. 6. What is meant by a bidirectional signal? i. A signal that propagates in either direction on a medium. 7. What are the primary differences between baseband technology and broadband technology? j. Baseband is a digital...
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...Chapter 7 The Data Link Layer It is the role of the OSI Data Link layer to prepare Network layer packets for transmission and to control access to the physical media. Frame. A PDU at the Data Link layer is called a frame. Node. A node is a device n a network. Media. The media are the physical means used to carry data signals. Network. A network is two or more devices connected to a common medium. The Data Link later performs two basic services: * Allows the upper layers to access the media using techniques such as framing * Controls how data is places onto the media and is received from the media using techniques such as media access control and error detection Data link layer protocols Different protocols may be govern how to format a in use for different media. frame for use on different media. At each hop along the path, an intermediary device accepts frames from one medium, decapsulates the frame and then forwards the packets in anew frame. The headers of each frame are formatted for the specific medium that it will cross. Upper Layer Access to Media The Data Link layer effectively insulates the communication processes at the higher layers from the media transitions that may occur end-to-end. It is responsible for controlling the transfer of frames across the media. Layer 2 protocols specify the encapsulation of a packet into a frame and the techniques for getting the encapsulated packet on...
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...Michael S Murphy | NET 125 Chapter 7: OSI Data Link Layer Vocabulary Exercise: Matching Term | Definition | a. Frame | a. Two or more devices connected to a common medium | b. Node | d. A layer of the Open Systems Interconnection (OSI) model that frames upper-layer data and controls how data is placed on a medium | c. Media | b. A device on a network | d. Network | e. The physical means used to carry data signals | e. Data Link | c. The protocol data unit (PDU) used in Layer 2 of the OSI model | Concept Questions 1. What are the two main jobs of the data link layer? * Allows the upper layers to access the media using techniques such as framing. * Controls how data is placed onto the media and is received from the media using techniques such as media access control (MAC) and error detection. 2. What is the difference between a logical network and a physical network? * Logical network refers a group of devices that associated by the arrangement of a hierarchical addressing scheme. * Physical network refers the connection of devices on a common media. 3. If the data link layer didn’t exist, what changes would be required of a network layer protocol such as Internet Protocol (IP)? Without the data link layer, a network layer protocol, like IP, would require provisions for connecting to every type of media that could exist along a delivery path. Vocabulary Exercise: Completion 1. The technique for getting a frame on and off a medium is called...
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...4/7/2012 Learning Objectives Chapter FOUR S y s t e m U n i t Reference: Shelly Cashman, Discovering Computers 2011, Living In Digital World, International Thompson Publishing, •Identify and describes components of system unit. •Describes the function of ALU and control unit. •Describes the machine cycle. •Describes types of RAM, Ports, Connectors of computer system. The System Unit The System Unit What is System Unit? Processor chips The hardware unit that houses a computer’s processor, memory chips, ports, and add-in boards Microprocessor- the smallest type of processor, with all of the processing capabilities of the Control Unit and ALU located on a single chip Processor chips Memory chips Ports Add-in boards The System Unit The System Unit Ports Memory chips SIMM (Single in-line memory module) – A multiple-chip memory card inserted as a unit into a Pre-designed slot on a computer’s system board. A connector through which peripheral devices can be plugged into the computer 1 4/7/2012 The System Unit Inside the System Unit Add-in boards A board that can be added to a computer to customize its features and capabilities. The Motherboard Type of Chips Single Edge Contact (SEC) – connects to the motherboard on one of its edges. Dual Inline Package (DIP) – consists of two parallel rows of downward pointing thin metal feet (pins). Type of Chips The Machine Cycle Memory Fetch I-Cycle Store ...
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...THEORY The correct answer(s): D What is the default IPX Ethernet encapsulation? A.) SNAP B.) Arpa C.) 802.2 D.) Novell-Ether E.) SAP Novell-ether is the default LAN encapsulation. Novell-ether is 802.3. The correct answer(s): A What must be true for two Routers running IGRP to communicate their routes? A.) Same autonomous system number B.) Connected using Ethernet only C.) Use composite metric D.) Configured for PPP For two routers to exchange IGRP routes they must be configured with the same autonomous system number. The correct answer(s): C The following is partial output from a routing table, identify the 2 numbers in the square brackets; '192.168.10.0 [100/1300] via 10.1.0.1, 00:00:23, Ethernet1' A.) 100 = metric, 1300 = administrative distance B.) 100 = administrative distance, 1300 = hop count C.) 100 = administrative distance, 1300 = metric D.) 100 = hop count, 1300 = metric The first number is the Administrative distance and the seconds number is the metric. In this case it is an IGRP metric. The correct answer(s): A B C Identify 3 methods used to prevent routing loops? A.) Split horizon B.) Holddown timers C.) Poison reverse D.) SPF algorithm E.) LSP's Routing loops can be prevented by split horizon, poison reverse and holddown times. The other two choices relate to Link State. The correct answer(s): A Which statement is true regarding full duplex? A.) Allows for transmission and receiving...
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