Using Information Technology Chapter 7 Networks & Communications. - презентация

1 Using Information Technology Chapter 7 Networks & Communications

2 Telecommunications 2 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Networks & Communications--The New Story in Computing 7.1From the Analog to the Digital Age 7.2The Practical Uses of Communications 7.3Communications Media and Transfer Rates 7.4Transmitting Data: Behind-the-Scenes Details

3 Telecommunications 3 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Networks & Communications--The New Story in Computing 7.5Networks 7.6The Future of Communications 7.7Cyberethics: Controversial Material and Censorship

4 Telecommunications 4 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. 7.1 From the Analog to the Digital Age Analog - continuously varying in strength and/or quality Digital - communications signals or information represented in a two-state (binary) way using electronic or electromagnetic signals

5 Telecommunications 5 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Purpose of the Modem - Converting Digital Signals to Analog Signals & Back Modem - short for modulate/demodulate Sending modem - modulates digital signals into analog signals for transmission over phone lines Receiving modem - demodulates the analog signals back into digital signals

6 Telecommunications 6 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. 7.2 The Practical Uses of Communications Videoconferencing & Videophones Videoconferencing - the use of television video and sound technology as well as computer to enable people in different locations to see, hear, and talk with one another

7 Telecommunications 7 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Workgroup Computing & Groupware Workgroup computing also called collaborative computing – teams of co-workers (often at different sites) use networks of microcomputers to share information and to cooperate on projects Made possible by networks, microcomputers, & groupware

8 Telecommunications 8 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Telecommuting Telecommuting - working at home while in telecommunication with the office

9 Telecommunications 9 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Virtual Offices Virtual office - an often nonpermanent and mobile office run with computer and communications technology

10 Telecommunications 10 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Smart Television Digital television (DTV) - uses a digital signal, or series of 0s and 1s High-definition television (HDTV) – works with digital broadcasting signals and has higher-resolution than standard television Standard-definition television (SDTV) - allows broadcasters to transmit more information within the HDTV bandwidth

11 Telecommunications 11 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. 7.3 Communications Media and Transfer Rates Communications media – carries signals over a communications path, the route between two or more communications media services

12 Telecommunications 12 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Wired Communications Media - Wires and Cables Twisted-pair wire - two strands of insulated copper wire, twisted around each other

13 Telecommunications 13 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Wired Communications Channels Coaxial cable - insulated copper wire wrapped in a solid or braided metal shield, then in an external cover

14 Telecommunications 14 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Wired Communications Channels Fiber-optic cable - dozens or hundreds of thin strands of glass or plastic that transmit pulsating beams of light rather than electricity Fiber-optic cableFiber-optic strand

15 Telecommunications 15 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. The Electromagnetic Spectrum, the Radio Spectrum, & Bandwidth Radio frequency spectrum

16 Telecommunications 16 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Wireless Communications Channels Infrared transmission - the transmission of data signals using infrared-light waves

17 Telecommunications 17 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Wireless Communications Channels Broadcast radio - a wireless transmission medium that sends data over long distances-- between regions, states, or countries Microwave radio - transmits voice & data through the atmosphere as super-high-frequency radio waves called microwaves

18 Telecommunications 18 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Wireless Communications Channels Communications satellites - microwave relay stations in orbit around the earth

19 Telecommunications 19 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Long-Distance Wireless Communications Global Positioning System (GPS) - 27 earth-orbiting satellites continuously transmitting timed radio signals that can be used to identify earth locationsGPS Car with GPS unit to guide users

20 Telecommunications 20 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Long-Distance Wireless Communications Pagers - simple radio receivers that receive data (but not voice messages) sent from a special radio transmitter

21 Telecommunications 21 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Long-Distance Wireless Communications Analog cellphones (known as 1G- first generation) - designed primarily for communicating by voice through a system of ground-area cells

22 Telecommunications 22 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Long-Distance Wireless Communications Digital wireless services (2G) - support digital cellphones & personal digital assistants by using a network of cell towers to send voice communications & data over the airwaves in digital form Broadband wireless digital services (3G) - always on technology which can quickly transmit video, still pictures, and music Cellphone tower

23 Telecommunications 23 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Short-Range Wireless Communications Bluetooth - a short-range wireless digital standard aimed at linking cellphones, PDAs, computers, & peripherals up to distances of 30 feet WiFi (wireless fidelity)- a short- range wireless digital standard aimed at helping portable computers and handheld wireless devices to communicate at high speeds and share internet connections at distances up to 300 feet

24 Telecommunications 24 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Compression & Decompression - Putting More Data in Less Space Compression - a method of removing repetitive elements from a file so that the file requires less storage space and therefore less time to transmit Lossless vs. lossy compression Compression standards

25 Telecommunications 25 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. 7.4 Transmitting Data - Behind-the-Scenes Details Line configurations Point-to-point line - directly connects the sending & receiving devices Multipoint line - a single line that interconnects several communications devices to one computer Factors Affecting Data Transmission

26 Telecommunications 26 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting Data Transmission Serial vs. parallel transmission Serial data transmission - bits are transmitted sequentially, one after the other Serial Data Transmission

27 Telecommunications 27 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting How Data Is Transmitted Serial vs. parallel transmission Parallel data transmission - bits are transmitted through separate lines simultaneously

28 Telecommunications 28 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting How Data Is Transmitted Direction of transmission - simplex, half-duplex, and full- duplex Simplex transmission - data can travel in only one direction

29 Telecommunications 29 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting How Data Is Transmitted Direction of transmission - simplex, half-duplex, and full- duplex Half-duplex transmission - data travels in both directions but only in one direction at a time

30 Telecommunications 30 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting How Data Is Transmitted Direction of transmission - simplex, half-duplex, and full- duplex Full-duplex transmission - data is transmitted back and forth at the same time

31 Telecommunications 31 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting How Data Is Transmitted Transmission mode - asynchronous vs. synchronous Asynchronous transmission - data is sent one byte at a time, with each string of bits making up the byte and bracketed with special control bits

32 Telecommunications 32 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting How Data Is Transmitted Transmission mode - asynchronous vs. synchronous Synchronous transmission - data is sent in blocks, with start and stop bit patterns (synch bytes) at the beginning and end of the blocks

33 Telecommunications 33 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting How Data Is Transmitted Circuit switching - transmitter has full use of the circuit until all the data has been transmitted and the circuit is terminated Packet switching - electronic messages are divided into packets for transmission over a wide area network to their destination, through the most expedient route

34 Telecommunications 34 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting How Data Is Transmitted Multiplexers Concentrators Front-end processors Multiplexing - transmission of multiple signals over a single communications channel

35 Telecommunications 35 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors Affecting How Data Is Transmitted Protocol - a set of conventions governing the exchange of data between hardware and/or software components in a communications network

36 Telecommunications 36 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. 7.5 Networks Benefits of networks - Sharing of peripheral devices Sharing of programs and data Better communications Security of information Access to databases

37 Telecommunications 37 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Types of Networks Wide area network (WAN) - a communications network that covers a wide geographical area, such as a country or the world

38 Telecommunications 38 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Types of Networks Metropolitan area network (MAN) - a communications network covering a city or a suburb Local area network (LAN) - connects computers and devices in a limited geographical area

39 Telecommunications 39 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Types of Networks Host computer - a mainframe or midsize central computer that controls the network Node - any device that is attached to a network Backbone - a high-speed network that connects LANs and MANs to the internet

40 Telecommunications 40 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Types of LANs Client/server LAN - Clients - microcomputers that request data Server - a powerful microcomputer that supplies data and manages shared devices

41 Telecommunications 41 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Types of LANs Peer-to-peer LAN - all microcomputers on the network communicate directly with one another without relying on a server

42 Telecommunications 42 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Components of LANs Connection or cabling system Microcomputers with network interface cards Network OS Other shared devices Routers, bridges, and gateways Hub

43 Telecommunications 43 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Topology of LANs Bus network – all nodes are connected to a single wire or cable, the bus, which has two endpoints Each communication device on the network transmits electronic messages to other devices.

44 Telecommunications 44 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Topology of LANs Ring network - all microcomputers and other communications devices are connected in a continuous loop

45 Telecommunications 45 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Topology of LANs Star network - all microcomputers and other communications devices are connected to a central server

46 Telecommunications 46 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Intranets, Extranets, & Firewalls IntranetIntranet - an organizations internal private network that uses the infrastructure and standards of the internet and the web Extranets - private intranets that connect not only internal personnel but also selected suppliers and other strategic parties Firewalls - a system of hardware and software that blocks unauthorized users inside and outside the organization from entering the intranet Virtual private network – are private networks that use a public network (usually the internet) to connect remote sites.

47 Telecommunications 47 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. 7.6 The Future of Communications Satellite-based systems - categorized into four types TV direct-broadcast system GPS system Satellite transmission to handle cellphone and paging services Global high-speed low-orbital satellite networks

48 Telecommunications 48 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Future of Communications Beyond 3G to 4G Photonics - optical technologies at warp speed Utilities become communications companies Software-defined radio The grid

49 Telecommunications 49 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. 7.7 Cyberethics Controversial material and censorship - Blocking software Browsers with ratings The V-Chip

50 Telecommunications 50 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What kind of signal varies continuously in strength and/or quality? Analog signal

51 Telecommunications 51 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. What is a general term for very high-speed connections? Broadband Concept Check

52 Telecommunications 52 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What type of cable consists of insulated copper wire wrapped in a solid or braided metal shield, then in an external cover? Coaxial (co-ax) cable

53 Telecommunications 53 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What are the three zones in space which satellite systems may occupy? GEO, MEO, and LEO

54 Telecommunications 54 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What system consists of a series of earth-orbiting satellites continuously transmitting timed radio signals that can be used to identify earth locations? Global Positioning System (GPS)

55 Telecommunications 55 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check Which modem modulates digital signals into analog signals for transmission over phone lines--a sending or receiving modem? Sending modem

56 Telecommunications 56 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What is the term for working at home while in telecommunication with the office? Telecommuting

57 Telecommunications 57 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What is the term for an often nonpermanent and mobile office run with computer and communications technology? Virtual office

58 Telecommunications 58 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What type of compression loses a certain amount of accuracy in exchange for a high degree of compression? Lossy compression

59 Telecommunications 59 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What is the leading compression standard for still images? JPEG

60 Telecommunications 60 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What type of transmission involves data traveling in both directions but only in one direction at a time? Half-duplex

61 Telecommunications 61 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What is the term for the transmission of multiple signals over a single communications channel? Multiplexing

62 Telecommunications 62 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What is the term for a set of conventions governing the exchange of data between hardware and/or software components in a communications network? Protocol

63 Telecommunications 63 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check Which type of LAN involves all microcomputers on the network communicating directly with one another without relying on a server? Peer-to-peer LAN

64 Telecommunications 64 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check Which LAN topology connects all microcomputers and other communications devices in a continuous loop? Ring network

65 Telecommunications 65 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What is an organizations internal private network that uses the infrastructure and standards of the internet and the web called? Intranet

66 Telecommunications 66 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What are Bluetooth, WiFi, and HomeRF examples of? Short-range wireless communications

67 Telecommunications 67 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What is the term for teams of co-workers using networks of microcomputers to share information and to cooperate on projects? Workgroup computing (collaborative computing)

68 Telecommunications 68 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What type of data transmission transmits bits sequentially, one after the other? Serial data transmission

69 Telecommunications 69 Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Concept Check What is a system of hardware and software that blocks unauthorized users inside and outside the organization from entering the intranet? Firewall