Data into a computer (via a keyboard) is encoded by the electronics within the keyboard into an equivalent binary-coded pattern using standard coding schemes:
Two most common schemes:
EBCDIC (Extended Binary Coded Decimal Interchange Code): 8-bit code
ASCII ((American Standards Committee for Information Interchange): 7-bit code
Data Link Layer. Learning Objectives
Upon completion of this chapter, you will be able to:
Explain the role of Data Link layer protocols in data transmission.
Describe how the Data Link layer prepares data for transmission on network media.
Describe the different types of media access control methods.
Identify several common logical network topologies and describe how the logical topology determines the media access control method for that network.
Explain the purpose of encapsulating packets into frames to facilitate media access. ...
Data communications and networking are changing the way we do business and the way
we live. Business decisions have to be made ever more quickly, and the decision makers
require immediate access to accurate information. Why wait a week for that report
from Germany to arrive by mail when it could appear almost instantaneously through
computer networks? Businesses today rely on computer networks and internetworks.
In this module, students will learn how to determine threats and analyze risks to
data transmission in an organization. Students will also learn how to design
security for different types of data transmission, including traffic on local area
networks (LANs), wide area networks (WANs), virtual private networks
(VPNs), wireless networks, and the Internet.
In a communication system, data are propagated from one point to another by means of
electromagnetic signals. A signal is a series of analogue or digital data. That is a varying voltage
(either continuous or discrete) with time in an electronic communication system.
Definitions of Data and Signals:
Analog Data - Data represented by a continuous physical quantity whose magnitude is proportion
a suitable function of the data (information). It can have more than two discrete values in
contrast to digital data. ...
Telephone networks use circuit switching. The telephone network had its beginnings in the late 1800s. The entire network, which is referred to as the plain old telephone system (POTS), was originally an analog system using analog signals to transmit voice.
Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài:
Research Article Secure and Efﬁcient Data Transmission over Body Sensor and Wireless Networks
All signal elements have same sign
One logic state represented by positive voltage the other by negative voltage
Rate of data transmission in bits per second
Duration or length of a bit
Time taken for transmitter to emit the bit
Congestion occurs when the number of packets being transmitted through the network approaches the packet handling capacity of the network
Congestion control aims to keep number of packets below level at which performance falls off dramatically
Data network is a network of queues
Generally 80% utilization is critical
Finite queues mean data may be lost
Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài:Link Adaptation for Framed Multimedia Data Transmission over a DS-CDMA Communication System
Upon completion of this chapter, you will be able to: Explain the role of Data Link layer protocols in data transmission, describe how the Data Link layer prepares data for transmission on network media, describe the different types of media access control methods,... Inviting you to refer.
The content in chapter 5 explain basic data transmission concepts, including full duplexing, attenuation, latency, and noise; describe the physical characteristics of coaxial cable, STP, UTP, and fiber-optic media; compare the benefits and limitations of different networking media;...
In this chapter, you learned to: Explain the role of Data Link layer protocols in data transmission, describe how the Data Link layer prepares data for transmission on network media, describe the different types of media access control methods,... Inviting you to refer.
Chapter 9 - Using telephoneand cable networks for data transmission. This chapter shows how the issues discussed in the previous chapters can be used in actual networks. In this chapter, we first discuss the telephone network as designed to carry voice. We then show how it can be used to carry data. Second, we discuss the cable network as a television network. We then show how it can also be used to carry data.
Chapter 6 - Physical layer. In this chapter, we study the duties of the physical layer, first as a converter that converts data to signals, then as a manager that controls the medium. After reading this chapter, the reader should be able to: Distinguish between analog and digital data, distinguish between analog and digital signals, understand the concept of bandwidth and the relationship between bandwidth and data transmission speed,...
There are many occasions when data need to be transmitted over a voice communication network.
Many people use a computer to connect to their Internet Service Provider via the telephone lines to
transmit and receive data, check their email, surf the Web, etc.
Telephone networks were originally built for human speech, not for computer data and is unsuitable for
digital communication in its raw form.