BAIT1003 Chapter 8


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  • An example of a communication system. Some devices that serve as sending devices and receiving devices are mainframe computers, servers, desktop computers, notebook computers, smart phones, Internet-enabled portable media players, handheld game consoles, and GPS receivers. The communication channel consists of telephone and power lines, cable television and other underground lines, microwave stations, and satellites.
  • BAIT1003 Chapter 8

    1. 1. BAIT1003 IT Fundamentals Chapter 8 Telecommunications
    2. 2. Objectives Discuss the purpose of the components required for successful communications and identify various sending and receiving devices Describe various types of lines for communications over the telephone network Describe commonly used communications devices Describe various physical and wireless transmission media
    3. 3. Introduction to Communications System Server Desktop computer Mainframe GPS receiver Smart phone Handheld game consoles Notebook Internet-enabled portable media players
    4. 4. Introduction to Communications System • Computer communications describes a process in which two or more computers or devices transfer data, instructions, and information. • For successful communication, you need the following: Sending device Communications channel Receiving device
    5. 5. Introduction to Communications System • A sending device initiates an instruction to transmit data, instructions, or information. • A communication channel is the medium on which the data, instructions, or information travel. • A communication device connects the sending or receiving device to a communication channel. • A receiving device accepts the transmission of data, instructions, or information.
    6. 6. Introduction to Communications System transmit data, instruction s, or information Communication channel or transmission media :telephone line, cable, airwave Sending device: computer, fax machine medium on which the data, instructions, or information travel modem connects the sending or receiving device to a communication channel Communication device: modem accepts the transmission of data, instructi ons, or information Receiving device : computer, fax machine
    7. 7. Servers • Sometimes called the host computer • Support from two to several thousands connected computers at the same time.
    8. 8. Purpose of Servers • The purpose of server is to control access to the hardware, software, and other resources on the network . • Provides a centralized storage area for programs, data, and information.
    9. 9. Types of Servers • Some servers, called dedicated servers, perform a specific task. • Examples: 1. File server stores and manages files. 2. Print server manages printers and documents being printed. 3. Network server manage network traffic (activity). 4. Web server delivers requested Web pages to your computer.
    10. 10. Types of Servers (Examples)
    11. 11. Types of Servers (Examples)
    12. 12. Communication Devices • A communications device is any type of hardware capable of transmitting data, instructions, and information between a sending device and a receiving device • Examples: 1. 2. 3. 4. 5. Modem Network cards Wireless access point Routers Hubs and switches
    13. 13. Communication Devices
    14. 14. Communication Devices - Modem • One type of communication device that connects a communications channel to a sending or receiving device is a MODEM. • The function of MODEM is to convert digital signals to analog signal and analog signal to digital, so that data can travel along an analog telephone line. • Types of MODEMs: 1. Dial up modems 2. Digital modem 3. Wireless modem
    15. 15. Communication Devices - Modem • A dial-up modem converts signals between analog and digital, so that data can travel along an analog telephone line. Usually is in the form of adapter card.
    16. 16. Communication Devices - Modem • A digital modem sends and receives data and information to and from a digital line. – Three types of digital modems are: 1. ISDN (Integrated Services Digital Network) modem – use ISDN line 2. DSL (Digital Subscriber Line) – use DSL line 3. Cable modem – called broadband modem, over the cable television network.
    17. 17. Communication Devices - Modem
    18. 18. Communication Devices - Modem • A wireless modem uses the cell phone network to connect to the Internet wirelessly from a notebook computer, a smart phone, or other mobile device • Wireless modem have an external or build-in antenna, are available as USB flash drive.
    19. 19. Communication Devices - Network Cards • A network card enables a computer or device that does not have build in networking capability to access a network. • Available in a variety of styles: – Desktop computer: is an adapter card that has a port to which a cable connects. – Mobile computer: USB network adapter, ExpressCard module, or PC Card.
    20. 20. Communication Devices - Wireless Access Points • A wireless access point is a central communications device that allows computers and devices to transfer data wirelessly among themselves or to a wired network. • It has high quality antennas for optimal signals and suggest positioning at the highest possible location.
    21. 21. Communication Devices - Routers • A router connects multiple computers or other routers together and transmits data to its correct destination on a network. – Example: – Home network – router allows multiple computers to share a single high speed Internet connection such as through a cable modem/DSL modem. • To prevent unauthorized users from accessing files and computer, many are protected by a build-in firewall.
    22. 22. Communication Devices - Hubs & Switches • A hub/ switch is a device that provides a central point for cables in a network. • Larger networks typically use a hub, while smaller networks use a switch. • Some hubs/switches include routers. That is, the hub/ switch receives data from many directions and then forward it to one or more destinations.
    23. 23. Communication Over Telephone Network • The public switched telephone network (PSTN) is the worldwide telephone system that handles voice oriented telephone calls. • The telephone network is an integral part of computer communication. • Data, instructions, and information are transmitted over the telephone network using dial up lines or dedicated lines.
    24. 24. Communication Over Telephone Network
    25. 25. Communication Over Telephone Network • Various types of lines that use the telephone • network for data communications. Dial-up lines Dedicated line FTTP ISDN line T-carrier line ATM DSL
    26. 26. Dial-up Lines vs. Dedicated Lines • A dial-up line is a temporary connection that uses analog telephone lines for communications. • A dedicated line is a type of always-on connection that uses analog or digital lines. • A dedicated line are better than dial up because dedicated lines provide a constant connection. • Five types of digital dedicated lines are ISDN lines, DSL, FTTP, T-carrier lines, and ATM.
    27. 27. ISDN vs. DSL • ISDN (Integrated Services Digital Network) lines is a set of standards for digital transmission of data over standard telephone lines. • DSL (Digital Subscriber Line) transmit at fast speeds on standard telephone lines with both voice and data communications.
    28. 28. ADSL • ADSL (Asymmetric DSL) is a type of DSL that supports faster transfer rates when receiving data (download) than when sending data (upload). • ADSL connections transmit data downstream at a much faster rate than upstream
    29. 29. SDSL • SDSL (Symmetric DSL) is a type of DSL that offers symmetric bandwidth upstream and downstream • SDSL connections transmit data only and does not support analog calls.
    30. 30. FTTP • FTTP (Fiber to the Premises) uses fiberoptic cable to provide extremely high-speed Internet access.
    31. 31. FTTP
    32. 32. T-Carrier Lines vs. ATM • T-carrier line is a long-distance digital telephone line that carry multiple signals over a single communications line. • ATM (Asynchronous Transfer Mode) is a service that carries voice, data, video, and multimedia at very high speeds.
    33. 33. Various Internet Connections
    34. 34. Communication Channel • It is the transmission media on which data, instructions travel in a communications system. • Common terms: – The amount of data that can travel over a communications channel sometimes is called the bandwidth – Latency is the time it takes a signal to travel from one location to another on a network – Transmission media consists of materials capable of carrying one or more signals – Broadband media transmit multiple signals simultaneously
    35. 35. Communication Channel
    36. 36. Communication Channel • Transmission media are one of two types: 1. Physical transmission media • Use wire, cable, and other tangible materials to send communication signal. • Examples: 1. 2. 3. Twisted pair cable Coaxial cable Fiber optic cable 2. Wireless transmission media • Send communications signals through the air or space using radio, microwave, and infrared signal.
    37. 37. Physical Transmission Media
    38. 38. Physical Transmission Media -Twisted-Pair Cable • Widely used in network cabling and telephone systems. • Twisted-pair cable consists of one or more twistedpair wires bundled together. • Each twisted pair wire consists of two separate insulated copper wires that are twisted together. • The wires are twisted together to reduce noise. Noise is an electrical disturbance that can degrade communications. • Commonly used for telephone lines • Speed: 1 – 128 Mbps
    39. 39. Physical Transmission Media -Twisted-Pair Cable Twisted-pair cable
    40. 40. Physical Transmission Media -Coaxial Cable • Coaxial cable consists of a single copper wire surrounded by three layers: - insulating material - woven or braided metal - plastic outer coating. • Commonly used for cable television network wiring • Speed: Up to 200 Mbps Coaxial cable
    41. 41. Physical Transmission Media -Fiber-Optic Cable • Fiber-optic cable consists of strands of glass (called optical fibers) that use light to transmit signals. • Speed:100 Mbps to 2 Gbps Fiber-optic cable
    42. 42. Physical Transmission Media -Fiber-Optic Cable • Advantages: – Carry more signals than wire cables – Faster data transmission – Less susceptible to noise, hence better security – Smaller size • Disadvantages: – Costs more than twisted-pair and coaxial cable – Difficult to install and modify
    43. 43. Wireless Transmission Media
    44. 44. Wireless Transmission Media -Infrared & Broadcast Radio • Infrared (IR) is a wireless transmission medium that sends signals using infrared light waves. – Communicate over short distance. – Use in mouse, printers, digital cameras, and hand phone. • Broadcast radio is a wireless transmission medium that distributes radio signals through the air over a long distances. – Example: Bluetooth
    45. 45. Wireless Transmission Media -Cellular Radio • Cellular radio is a form of broadcast radio that is used widely for mobile communications. specifically wireless modems and cell phones. – Several categories of cellular transmission: • • • • 1G transmit analog data 2G transmit digital data at speeds from 9.6kbps to 19.2kbps 3G transmit digital data at speeds from 144kbps to 2.4Mbps 4G transmit digital data at speeds up to 15Mbps
    46. 46. Wireless Transmission Media -Cellular Radio
    47. 47. Wireless Transmission Media -Microwaves Line-of-sight transmission- must transmit in straight line with no obstructions • Microwaves are radio waves that provide a high-speed signal transmission. • Often called fixed wireless, involves sending signals from one Microwave microwave station to station / another. earth-based station Microwave stations need to be placed within 25-30 miles of each other
    48. 48. Wireless Transmission Media -Communication Satellite • A communications satellite is a space station that receives microwave signals from an earth-based station, amplifies it, and broadcasts the signal over a wide area Applications such as air navigating, television and radio broadcast, weather forecasting, video conferencing, paging, global positioning systems, and Internet connections use communications satellite.
    49. 49. Summary Overview of communications terminology and applications Various communications devices, media, and procedures