Management Information Systems

WELCOME TO THE SESSION ON MIS CH-6: TELECOMMUNICATIONS AND NETWORKS Dr. Engr. Jnan Ranjan Sil, PHF BSc.Engg(civil), MBA(HRM), Doctor of Business Administration, PhD in Civil Engg.

TELECOMMUNICATIONS AND NETWORKS: Objectives : • At many points in your career, you will need to make decisions about how to use telecommunications technology and services in your business. In this chapter you will be able to know the following: -• What technologies are used in telecommunication systems?

• What telecommunications transmission media should our organization use?

• How should our organization design its networks?

• What telecommunication applications can be used for ebusiness and e-commerce?

6.1 Components and Functions of a Telecommunications System: • Telecommunication is the communication of information by electronic means, usually over some distance.

• Previously, telecommunication meant voice transmission over telephone lines.

• Today, a great deal of telecommunications transmission is digital data transmission, using computers to transmit data from one location to another.

Telecommunication system: A telecommunication system is a collection of compatible hardware and software arranged to communicate information from one location to another. communication channels

Host computer

Mid-range computer Terminals

Front-end computer multiplexer

Modem Modems

Fig: Components of a Telecommunication system

Terminals

multiplexer

Q. What are the Components of a Telecommunications system?

1. Computers to process information 2. Terminals or any input/output devices that send or receive data 3. Communications channels, the link by which data or voice are transmitted between sending and receiving devices in a network. Communications channels use various communications media, such as telephone line, coaxial cable, fiber-optic cable, and wireless transmission.

4. Communications processers, such as modems, multiplexers, controllers, and front-end processors, which provide support functions for data transmission and reception 5. Communications software, which controls input and output activities and manages other functions of the communication network.

Q. What are the functions of telecommunications systems?

• In order to send and receive information from one place to another, a telecommunications system must perform a number of separate functions.

• The system transmits information, • Establishes the interface between the sender and receiver, • Routes messages along the most efficient paths, • Performs elementary processing of the information to ensure that the right message gets to the right receiver, • Performs editorial tasks on the data( such as checking for transmission errors and rearranging the format),and • Converts messages from one speed into the speed of a communications line or from one format to another, • Finally, the telecommunications system controls the flow of information.

TYPES OF SIGNALS: • Information travels through a telecommunications system in the form of electromagnetic signals.

• Signals are represented in two ways: analog and digital signals.

• A analog signal is represented by a continuous wave form that passes through a communications medium. Analog signals are used to handle voice communications and to reflect variations in pitch.

• A digital signal is a discrete, rather than a continuous, wave form. It transmit data coded into two discrete states: 1-bits and 0-bits, which are represented as on – off electrical pulses. Most computers communicate with digital signals, as do many local telephone companies and some larger network.

Q. What do you meant by modem? What function does modem do?

• Modem: A device for translating digital signals into analog signals and vice versa.

• Modem is an abbreviation for MOdulation/DEModulation • A modem translates a computer’s digital signals into analog form for transmission over telephone lines, or it translates analog signals back into digital form for reception by a computer. digital analog digital 1 1 Computer

1

0

1

0

Modem

Figure: Functions of the Modem

Modem

0

0

Computer

COMMUNICATIONS CHANNELS: Communications channels are the means by which data are transmitted from one device in a network to another.

• A channel can use different kinds of telecommunications transmission media: • Twisted wire • Coaxial cable • Fiber optics, • Terrestrial microwave • Satellite, and • Other wireless transmission.

• Fiber-optic cable: A fast, light, and durable transmission medium consisting of thin strands of clear glass fiber bound into cables.

Data are transmitted as light pulses, which are sent through the fiber-optic cable by a laser device at a rate from 500 kilobits to several trillion bits per second. • Protocol: A set of rules and procedures that govern transmission between the components in a network. • Satellite: The transmission of data using orbiting satellites that serve as relay stations for transmitting microwave signals over very long distances.

• Paging system: A wireless transmission technology in which the pager beeps when the user receives a message; used to transmit short alphanumeric messages.

• Cellular telephone(Cellphone): A device that transmits voice or data, using radio waves to communicate with radio antennas placed within adjacent geographic areas called cells.

• Smart phone: wireless phone with voice, text, and internet capabilities.

• PDA( Personal Digital Assistants): Small, pen-based, handheld computers with built-in wireless telecommunications capable of entirely digital communications transmission.

• Baud: A change in signal from positive to negative or vice versa that is used as a measure of transmission speed.

• Bandwidth: The capacity of a communications channel as measured by the difference between the highest and lowest frequencies that can be transmitted by that channel.

• Multiplexer: A device that enables a single communications channel to carry data transmissions from multiple sources simultaneously.

• Bluetooth: Standard for wireless personal are networks that can transmit up to 720 kbps within a 10 meter area.

• WAN(Wide Area Network): Telecommunications

network that spans a large geographical distance. May consists of a variety of cable, satellite, and microwave technologies.

• Broadband: High-speed transmission technology.

Also designates a single communications medium that can carry multiple channels of data simultaneously.

• Voice mail: A system for digitizing a spoken message and transmitting it over a network.

• Facsimile(fax): A machine that digitizes and transmits documents with both text and graphics over telephone lines.

• Teleconferencing: The ability to confer with a group pf people simultaneously using the telephone or electronic-mail group communication software.

• Data conferencing: Teleconferencing in which two or more users are able to edit and modify data files simultaneously.

• Videoconferencing: Teleconferencing in which participants see each other over video screens.

• EDI(Electronic Data Interchange): The direct computer – to – computer exchange between two organizations of standard business transaction documents.

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