Data Communications Transmission System: Structure and Function
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Data Communication and Computer Network Unit 1
Department of Collegiate Education GOVERNMENT FIRST GRADE COLLEGE RAIBAG-591317 Department of Computer Science Lecture Notes SUBJECT : DATA COMMUNICATIONS AND COMPUTER NETWORKS SUBJECT CODE : 17BScCST61 CLASS : BSC VI Sem Paper-1 Subject In charge Smt Bhagirathi Halalli Assistant Professor 2019-20 Data Communication and Computer Network Unit 1 Unit 1: Introduction Content: 1.1. Data communications, 1.2. Networks, 1.3. The internet, 1.4. Protocols and standards, 1.5. Network models – OSI model, 1.6. TCP/IP protocol suite, 1.7. Addressing. 1.1.Data Communications, Data refers to the raw facts that are collected while information refers to processed data that enables us to take decisions. Ex. When result of a particular test is declared it contains data of all students, when you find the marks you have scored you have the information that lets you know whether you have passed or failed. The word data refers to any information which is presented in a form that is agreed and accepted upon by is creators and users. Data Communication Data Communication is a process of exchanging data or information In case of computer networks this exchange is done between two devices over a transmission medium. This process involves a communication system which is made up of hardware and software. The hardware part involves the sender and receiver devices and the intermediate devices through which the data passes. The software part involves certain rules which specify what is to be communicated, how it is to be communicated and when. It is also called as a Protocol. The following sections describe the fundamental characteristics that are important for the effective working of data communication process and are followed by the components that make up a data communications system. -
The OSI Model
Data Encapsulation & OSI & TCP/IP Models Week 2 Lecturer: Lucy White [email protected] Office : 324 1 Network Protocols • A protocol is a formal description of a set of rules and conventions that govern a particular aspect of how devices on a network communicate. Protocols determine the format, timing, sequencing, flow control and error control in data communication. Without protocols, the computer cannot make or rebuild the stream of incoming bits from another computer into the original format. • Protocols control all aspects of data communication, which include the following: - How the physical network is built - How computers connect to the network - How the data is formatted for transmission - The setting up and termination of data transfer sessions - How that data is sent - How to deal with errors 2 Protocol Suites & Industry Standard • Many of the protocols that comprise a protocol suite reference other widely utilized protocols or industry standards • Institute of Electrical and Electronics Engineers (IEEE) or the Internet Engineering Task Force (IETF) • The use of standards in developing and implementing protocols ensures that products from different manufacturers can work together for efficient communications 3 Function of Protocol in Network Communication A standard is a process or protocol that has been endorsed by the networking industry and ratified by a standards organization 4 Protocol Suites TCP/IP Protocol Suite and Communication Function of Protocol in Network Communication 6 Function of Protocol in Network Communication • Technology independent Protocols -Many diverse types of devices can communicate using the same sets of protocols. This is because protocols specify network functionality, not the underlying technology to support this functionality. -
Discrete Cosine Transform Based Image Fusion Techniques VPS Naidu MSDF Lab, FMCD, National Aerospace Laboratories, Bangalore, INDIA E.Mail: [email protected]
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by NAL-IR Journal of Communication, Navigation and Signal Processing (January 2012) Vol. 1, No. 1, pp. 35-45 Discrete Cosine Transform based Image Fusion Techniques VPS Naidu MSDF Lab, FMCD, National Aerospace Laboratories, Bangalore, INDIA E.mail: [email protected] Abstract: Six different types of image fusion algorithms based on 1 discrete cosine transform (DCT) were developed and their , k 1 0 performance was evaluated. Fusion performance is not good while N Where (k ) 1 and using the algorithms with block size less than 8x8 and also the block 1 2 size equivalent to the image size itself. DCTe and DCTmx based , 1 k 1 N 1 1 image fusion algorithms performed well. These algorithms are very N 1 simple and might be suitable for real time applications. 1 , k 0 Keywords: DCT, Contrast measure, Image fusion 2 N 2 (k 1 ) I. INTRODUCTION 2 , 1 k 2 N 2 1 Off late, different image fusion algorithms have been developed N 2 to merge the multiple images into a single image that contain all useful information. Pixel averaging of the source images k 1 & k 2 discrete frequency variables (n1 , n 2 ) pixel index (the images to be fused) is the simplest image fusion technique and it often produces undesirable side effects in the fused image Similarly, the 2D inverse discrete cosine transform is defined including reduced contrast. To overcome this side effects many as: researchers have developed multi resolution [1-3], multi scale [4,5] and statistical signal processing [6,7] based image fusion x(n1 , n 2 ) (k 1 ) (k 2 ) N 1 N 1 techniques. -
Logical Link Control and Channel Scheduling for Multichannel Underwater Sensor Networks
ICST Transactions on Mobile Communications and Applications Research Article Logical Link Control and Channel Scheduling for Multichannel Underwater Sensor Networks Jun Li ∗, Mylene` Toulgoat, Yifeng Zhou, and Louise Lamont Communications Research Centre Canada, 3701 Carling Avenue, Ottawa, ON. K2H 8S2 Canada Abstract With recent developments in terrestrial wireless networks and advances in acoustic communications, multichannel technologies have been proposed to be used in underwater networks to increase data transmission rate over bandwidth-limited underwater channels. Due to high bit error rates in underwater networks, an efficient error control technique is critical in the logical link control (LLC) sublayer to establish reliable data communications over intrinsically unreliable underwater channels. In this paper, we propose a novel protocol stack architecture featuring cross-layer design of LLC sublayer and more efficient packet- to-channel scheduling for multichannel underwater sensor networks. In the proposed stack architecture, a selective-repeat automatic repeat request (SR-ARQ) based error control protocol is combined with a dynamic channel scheduling policy at the LLC sublayer. The dynamic channel scheduling policy uses the channel state information provided via cross-layer design. It is demonstrated that the proposed protocol stack architecture leads to more efficient transmission of multiple packets over parallel channels. Simulation studies are conducted to evaluate the packet delay performance of the proposed cross-layer protocol stack architecture with two different scheduling policies: the proposed dynamic channel scheduling and a static channel scheduling. Simulation results show that the dynamic channel scheduling used in the cross-layer protocol stack outperforms the static channel scheduling. It is observed that, when the dynamic channel scheduling is used, the number of parallel channels has only an insignificant impact on the average packet delay. -
Digital Signals
Technical Information Digital Signals 1 1 bit t Part 1 Fundamentals Technical Information Part 1: Fundamentals Part 2: Self-operated Regulators Part 3: Control Valves Part 4: Communication Part 5: Building Automation Part 6: Process Automation Should you have any further questions or suggestions, please do not hesitate to contact us: SAMSON AG Phone (+49 69) 4 00 94 67 V74 / Schulung Telefax (+49 69) 4 00 97 16 Weismüllerstraße 3 E-Mail: [email protected] D-60314 Frankfurt Internet: http://www.samson.de Part 1 ⋅ L150EN Digital Signals Range of values and discretization . 5 Bits and bytes in hexadecimal notation. 7 Digital encoding of information. 8 Advantages of digital signal processing . 10 High interference immunity. 10 Short-time and permanent storage . 11 Flexible processing . 11 Various transmission options . 11 Transmission of digital signals . 12 Bit-parallel transmission. 12 Bit-serial transmission . 12 Appendix A1: Additional Literature. 14 99/12 ⋅ SAMSON AG CONTENTS 3 Fundamentals ⋅ Digital Signals V74/ DKE ⋅ SAMSON AG 4 Part 1 ⋅ L150EN Digital Signals In electronic signal and information processing and transmission, digital technology is increasingly being used because, in various applications, digi- tal signal transmission has many advantages over analog signal transmis- sion. Numerous and very successful applications of digital technology include the continuously growing number of PCs, the communication net- work ISDN as well as the increasing use of digital control stations (Direct Di- gital Control: DDC). Unlike analog technology which uses continuous signals, digital technology continuous or encodes the information into discrete signal states (Fig. 1). When only two discrete signals states are assigned per digital signal, these signals are termed binary si- gnals. -
Data Networks
Second Ed ition Data Networks DIMITRI BERTSEKAS Massachusetts Institute of Technology ROBERT GALLAGER Massachusetts Institute ofTechnology PRENTICE HALL, Englewood Cliffs, New Jersey 07632 2 Node A Node B Time at B --------- Packet 0 Point-to-Point Protocols and Links 2.1 INTRODUCTION This chapter first provides an introduction to the physical communication links that constitute the building blocks of data networks. The major focus of the chapter is then data link control (i.e., the point-to-point protocols needed to control the passage of data over a communication link). Finally, a number of point-to-point protocols at the network, transport, and physical layers are discussed. There are many similarities between the point-to-point protocols at these different layers, and it is desirable to discuss them together before addressing the more complex network-wide protocols for routing, flow control, and multiaccess control. The treatment of physical links in Section 2.2 is a brief introduction to a very large topic. The reason for the brevity is not that the subject lacks importance or inherent interest, but rather, that a thorough understanding requires a background in linear system theory, random processes, and modem communication theory. In this section we pro vide a sufficient overview for those lacking this background and provide a review and perspective for those with more background. 37 38 Point-to-Point Protocols and Links Chap. 2 In dealing with the physical layer in Section 2.2, we discuss both the actual com munication channels used by the network and whatever interface modules are required at the ends of the channels to transmit and receive digital data (see Fig 2.1). -
How I Came up with the Discrete Cosine Transform Nasir Ahmed Electrical and Computer Engineering Department, University of New Mexico, Albuquerque, New Mexico 87131
mxT*L. BImL4L. PRocEsSlNG 1,4-5 (1991) How I Came Up with the Discrete Cosine Transform Nasir Ahmed Electrical and Computer Engineering Department, University of New Mexico, Albuquerque, New Mexico 87131 During the late sixties and early seventies, there to study a “cosine transform” using Chebyshev poly- was a great deal of research activity related to digital nomials of the form orthogonal transforms and their use for image data compression. As such, there were a large number of T,(m) = (l/N)‘/“, m = 1, 2, . , N transforms being introduced with claims of better per- formance relative to others transforms. Such compari- em- lh) h = 1 2 N T,(m) = (2/N)‘%os 2N t ,...) . sons were typically made on a qualitative basis, by viewing a set of “standard” images that had been sub- jected to data compression using transform coding The motivation for looking into such “cosine func- techniques. At the same time, a number of researchers tions” was that they closely resembled KLT basis were doing some excellent work on making compari- functions for a range of values of the correlation coef- sons on a quantitative basis. In particular, researchers ficient p (in the covariance matrix). Further, this at the University of Southern California’s Image Pro- range of values for p was relevant to image data per- cessing Institute (Bill Pratt, Harry Andrews, Ali Ha- taining to a variety of applications. bibi, and others) and the University of California at Much to my disappointment, NSF did not fund the Los Angeles (Judea Pearl) played a key role. -
MC14SM5567 PCM Codec-Filter
Product Preview Freescale Semiconductor, Inc. MC14SM5567/D Rev. 0, 4/2002 MC14SM5567 PCM Codec-Filter The MC14SM5567 is a per channel PCM Codec-Filter, designed to operate in both synchronous and asynchronous applications. This device 20 performs the voice digitization and reconstruction as well as the band 1 limiting and smoothing required for (A-Law) PCM systems. DW SUFFIX This device has an input operational amplifier whose output is the input SOG PACKAGE CASE 751D to the encoder section. The encoder section immediately low-pass filters the analog signal with an RC filter to eliminate very-high-frequency noise from being modulated down to the pass band by the switched capacitor filter. From the active R-C filter, the analog signal is converted to a differential signal. From this point, all analog signal processing is done differentially. This allows processing of an analog signal that is twice the amplitude allowed by a single-ended design, which reduces the significance of noise to both the inverted and non-inverted signal paths. Another advantage of this differential design is that noise injected via the power supplies is a common mode signal that is cancelled when the inverted and non-inverted signals are recombined. This dramatically improves the power supply rejection ratio. After the differential converter, a differential switched capacitor filter band passes the analog signal from 200 Hz to 3400 Hz before the signal is digitized by the differential compressing A/D converter. The decoder accepts PCM data and expands it using a differential D/A converter. The output of the D/A is low-pass filtered at 3400 Hz and sinX/X compensated by a differential switched capacitor filter. -
Telecommunications Technology Transfers Contents
CHAPTER 6 Telecommunications Technology Transfers Contents Page INTRODUCTION . 185 TELECOMMUNICATIONS IN THE MIDDLE EAST . 186 Telecommunications Systems . 186 Manpower Requirements . 190 Telecommunications Systems in the Middle East. ........: . 191 Perspectives of Recipient Countries and Firms . 211 Perspectives of Supplier Countries and Firms . 227 IMPLICATIONS FOR U.S. POLICY . 236 CONCLUSIONS . 237 APPENDIX 6A. – TELECOMMUNICATIONS PROJECT PROFILES IN SELECTED MIDDLE EASTERN COUNTRIES. 238 Saudi Arabian Project Descriptions . 238 Egyptian Project Descriptions . 240 Algerian Project Description . 242 Iranian Project Description . 242 Tables Table No. Page 51. Market Shares of Telecommunications Equipment Exports to Saudi Arabia From OECD Countries, 1971, 1975-80 . 194 52. Selected Telecommunications Contracts in Saudi Arabia . 194 53. Market Shares of Telecommunications Equipment Exports to Kuwait From OECD Countries, 1971,1975-80 . 198 54. Selected Telecommunications Contracts in Kuwait . 198 55. Market Shares of Telecommunications Equipment Exports From OECD Countries, 1971, 1975-80 . 202 56. Market Shares of Telecommunications Equipment Exports to Algeria From OECD Countries, 1971,1975-80 . 204 57. Market Shares of Telecommunications Equipment Exports to Iraq From OECD Countries, 1971, 1975-80 . 206 58. Selected Telecommunications Contracts in Iraq . 206 59. Market Shares of Telecommunications Equipment Exports to Iran From OECD Countries, 1971, 1975-80 . 208 60. Saudi Arabian Telecommunications Budgets As Compared to Total Budgets . 212 61. U.S. Competitive Position in Telecommunications Markets in the Middle East Between 1974 and 1982 . 233 Figures Page l0. Apparent Telecommunications Sector Breakdowns-Saudi Arabia, 1974-82 . 195 11. Apparent Market Share, Saudi Arabia, 1974-82 . 196 12. Apparent Sector Breakdowns-Kuwait, 1974-82 . 197 13. Apparent Market Share-Kuwait, 1974-82 . -
Reception Performance Improvement of AM/FM Tuner by Digital Signal Processing Technology
Reception performance improvement of AM/FM tuner by digital signal processing technology Akira Hatakeyama Osamu Keishima Kiyotaka Nakagawa Yoshiaki Inoue Takehiro Sakai Hirokazu Matsunaga Abstract With developments in digital technology, CDs, MDs, DVDs, HDDs and digital media have become the mainstream of car AV products. In terms of broadcasting media, various types of digital broadcasting have begun in countries all over the world. Thus, there is a demand for smaller and thinner products, in order to enhance radio performance and to achieve consolidation with the above-mentioned digital media in limited space. Due to these circumstances, we are attaining such performance enhancement through digital signal processing for AM/FM IF and beyond, and both tuner miniaturization and lighter products have been realized. The digital signal processing tuner which we will introduce was developed with Freescale Semiconductor, Inc. for the 2005 line model. In this paper, we explain regarding the function outline, characteristics, and main tech- nology involved. 22 Reception performance improvement of AM/FM tuner by digital signal processing technology Introduction1. Introduction from IF signals, interference and noise prevention perfor- 1 mance have surpassed those of analog systems. In recent years, CDs, MDs, DVDs, and digital media have become the mainstream in the car AV market. 2.2 Goals of digitalization In terms of broadcast media, with terrestrial digital The following items were the goals in the develop- TV and audio broadcasting, and satellite broadcasting ment of this digital processing platform for radio: having begun in Japan, while overseas DAB (digital audio ①Improvements in performance (differentiation with broadcasting) is used mainly in Europe and SDARS (satel- other companies through software algorithms) lite digital audio radio service) and IBOC (in band on ・Reduction in noise (improvements in AM/FM noise channel) are used in the United States, digital broadcast- reduction performance, and FM multi-pass perfor- ing is expected to increase in the future. -
Chapter 1 Computers and Digital Basics Computer Concepts 2014 1 Your Assignment…
Chapter 1 Computers and Digital Basics Computer Concepts 2014 1 Your assignment… Prepare an answer for your assigned question. Use Chapter 1 in the book and this PowerPoint to procure information. Prepare a PowerPoint presentation to: 1. Show your answer and additional information/facts – make sure you understand and can explain your answer. Provide as must information and detail as possible. Add graphics to enhance. 2. Where in the book did you find your information? Include the page number. 3. What more do you need to find out to help you better understand this question? Be prepared to share your information with the class. Chapter 1: Computers and Digital Basics 2 1 The Digital Revolution The digital revolution is an ongoing process of social, political, and economic change brought about by digital technology, such as computers and the Internet The technology driving the digital revolution is based on digital electronics and the idea that electrical signals can represent data, such as numbers, words, pictures, and music Chapter 1: Computers and Digital Basics 6 1 The Digital Revolution Digitization is the process of converting text, numbers, sound, photos, and video into data that can be processed by digital devices The digital revolution has evolved through four phases, beginning with big, expensive, standalone computers, and progressing to today’s digital world in which small, inexpensive digital devices are everywhere Chapter 1: Computers and Digital Basics 7 1 The Digital Revolution Chapter 1: Computers and Digital Basics -
UNIT: 3 Digital and Analog Transmission
UNIT: 3 Digital and Analog Transmission DIGITAL-TO-ANALOG CONVERSION Digital-to-analog conversion is the process of changing one of the characteristics of an analog signal based on the information in digital data. Figure 5.1 shows the relationship between the digital information, the digital-to-analog modulating process, and the resultant analog signal. A sine wave is defined by three characteristics: amplitude, frequency, and phase. When we vary anyone of these characteristics, we create a different version of that wave. So, by changing one characteristic of a simple electric signal, we can use it to represent digital data. Before we discuss specific methods of digital-to-analog modulation, two basic issues must be reviewed: bit and baud rates and the carrier signal. Aspects of Digital-to-Analog Conversion Before we discuss specific methods of digital-to-analog modulation, two basic issues must be reviewed: bit and baud rates and the carrier signal. Data Element Versus Signal Element Data element is the smallest piece of information to be exchanged, the bit. We also defined a signal element as the smallest unit of a signal that is constant. Data Rate Versus Signal Rate We can define the data rate (bit rate) and the signal rate (baud rate). The relationship between them is S= N/r baud where N is the data rate (bps) and r is the number of data elements carried in one signal element. The value of r in analog transmission is r =log2 L, where L is the type of signal element, not the level. Carrier Signal In analog transmission, the sending device produces a high-frequency signal that acts as a base for the information signal.