Understanding Telecommunication Signals and Trends in Communication

Lecturer: Dr. Ebenezer Ankrah, Dept. of Information Studies Contact Information: eankrah@ug.edu.gh College of Education School of Continuing and Distance Education 2014/2015 2016/2017

Session Overview Telecommunications have become an essential part of our lives. The use of online systems has expanded rapidly. Today a large proportion of new systems have some portion that is online, such as data entry, update and/or inquiry. At the same time, there has been an expansion in the number of alternatives available for establishing communications among computer systems. One has a choice from dial-up phone services to private networks using satellite for transmission. This session provides insight into the types of signals, modes of transmission and telecommunication media used in telecommunications. Slide 2

Session Overview At the end of the session, the student will Understand and explain the difference between digital signals and analog signals. Be able to identify the types of transmission media. Be able to understand the modes of transmission. Be able to understand the current trends in telecommunication. Understand the difference between modulation and demodulation. Slide 3

Session Outline The key topics to be covered in the session are as follows: Types of signals Transmission Modes Types of Communication media Trends in Telecommunications Slide 4

Reading List http://ecomputernotes.com/computernetworkingnotes/com munication-networks/what-are-the-different-transmission- modes http://ccm.net/contents/ Williams, B. K., & Sawyer, S. C. (2014). Using Information Technology: A practical introduction to computers and communications (11th ed.). McGraw-Hill Education. (Chapter 7) Slide 5

Topic One TYPES OF SIGNALS Slide 6

Types of signals Telecommunication technology links different pieces of hardware and transfers data from one location to another. It involves both physical media and software that support communication by electronic means. It establishes an interface between sender and receiver. Telecommunication is the exchange of information in any form such as Voice and Data (text, image, audio and video). Slide 7

Types of signals There are two types of signals, namely; Analog signal and Digital signal. Analog Signal A continuous wave used for voice transmission. Most telephone lines used to rely on analog signals for transmission. Slide 8

Types of signals Digital Signal A discrete burst rather than continuous wave. Transmits electrical pulses. Most computers communicate with digital signal. Slide 9

Types of signals The process of converting digital signals into analog form is called Modulation. The process of converting analog signals back into digital form is called Demodulation. Modemis a device that is used for the translation process. A modem translates digital signals into analog form and vice versa. Slide 10

Types of signals A modem is a device that translates digital signals from a computer into analog form so that they can be transmitted over analog telephone lines. The modem also translates analog signals back into digital form for the receiving computer. Slide 11

Topic Two TRANSMISSION MODES Slide 12

Transmission Modes The term Transmission Mode defines the direction of the flow of information between two communication devices, that is it tells the direction of signal flow between the two devices. There are three ways or modes of data transmission: Simplex, Half duplex (HDX), Full duplex (FDX) Slide 13

Transmission Modes Simplex In Communication Networks, Communication can take place in one direction connected to such a circuit are either a send only or receive only device. There is no mechanism for information to be transmitted back to the sender. Communication is unidirectional. TV broadcasting is an example. Simplex transmission generally involves dedicated circuits. Simplex circuits are analogous to escalators, doorbells, fire alarms and security systems: Data can only flow in one direction. Slide 14

Transmission Modes Communication between a computer and a keyboard involves simplex transmission. A television broadcast is an example of simplex transmission. Another example of simplex transmission is loudspeaker system. An announcer speaks into a microphone and his/her voice is sent through an amplifier and then to all the speakers. 3. Many fire alarm systems work the same way. Slide 15

Transmission Modes Half-Duplex A half duplex system can transmit data in both directions, but only in one direction at a time that mean half duplex modes support two-way traffic but in only one direction at a time. The interactive transmission of data within a time sharing system may be best suited to half-duplex lines. Both the connected devices can transmit and receive but not simultaneously. When one device is sending the other can only receive and vice- versa. Data is transmitted in one direction at a time, for example. a walkie-talkie. Slide 16

Transmission Modes This is generally used for relatively low-speed transmission, usually involving two-wire, analog circuits. Due to switching of communication direction, data transmission in this mode requires more time and processes than under full duplex mode. Examples of half duplex application include line printers, polling of buffers, and modem communications. Slide 17

Transmission Modes A walkie-talkie operates in half duplex mode. It can only send or receive a transmission at any given time. It cannot do both at the same time. As shown, computer A sends information to computer B. At the end of transmission, computer B sends information to computer A. computer A cannot send any information to computer B, while computer B is transmitting data. Slide 18

Transmission Modes Full-Duplex A full duplex system can transmit data simultaneously in both directions on transmission path. Full-duplex method is used to transmit the data over a serial communication link. Two wires needed to send data over a serial communication link layer. Full- duplex transmission, the channel capacity is shared by both communicating devices at all times. Both the connected devices can transmit and receive at the same time. Therefore it represents truly bi-directional system. The link may contain two separate transmission paths one for sending and another for receiving. Slide 19

Transmission Modes Telephone networks operate in full duplex mode when two persons talk on telephone line, both can listen and speak simultaneously. Slide 20

Topic Three TYPES OF COMMUNICATION MEDIA Slide 21

Types of Communication Media The hardware used to transmit data across the network is called the media. The types are; twisted pair wire, coaxial cable, fiber optics, microwave systems, communication satellites and cellular systems. Twisted Pair Cables The wires are twisted to minimize crosstalk interference. It may be shielded Twisted Pair (STP) or unshielded twisted pair (UTP). Slide 22

Types of Communication Media Normally UTP contains 8 wires or 4 pair and 100 meters maximum length. 4-100 Mbps speed. Shielded twisted pair also has 100 meters maximum length, 16-155 Mbps speed and lower electrical interference than UTP. Twisted pair wire consists of strands of copper wire twisted in pairs and is an older type of transmission medium. It is used for both analog and digital communication. It is used in today s LANs (CAT 5). It is low in cost and relatively slow. Slide 23

Types of Communication Media Coaxial Cables Coaxial cable consists of thickly insulated copper wire, which can transmit a large volume of data than twisted pair wire. It is used for cable television. It does not support analog phone conversation. There are two types of coaxial cables; Thinnet and the Thicknet. Slide 24

Types of Communication Media Thinnet Thinnet uses a British Naval Connector (BNC) on each end. Thinnet is part of the RG-58 family of cable. Maximum cable length is 185 meters. Transmission speed is10Mbps. Thinnet cables should have 50 ohms impedance and its terminator has 50 ohms impedance. Thicknet Maximum cable length is 500 meters and the transmission speed is 10Mbps. Thicknet are expensive and is not commonly used. A vampire tap or piercing tap is used with a transceiver attached to connect computers to the cable. Slide 25

Types of Communication Media Fiber Optics Fiber optic consists of bound strands of clear glass fiber, each the thickness of a human hair. It is considerably faster, lighter, and more durable than wire media. It is more expensive and harder to install. It is used primarily for the high-speed network backbones but now telecommunications companies are starting to bring fiber lines into the home for new types of services, such as ultra high-speed Internet access and on demand video. Data are transformed into pulses of light, which are sent through the fiber-optic cable by a laser device at rates varying from 500Kb to several trillion bits per second. Slide 26

Types of Communication Media Wireless Transmission Media Wireless transmission is based on radio signals of various frequencies. Microwave Systems Transmit high-frequency radio signals through the atmosphere. It is widely used for high-volume, long distance, point-to-point communication. It follows a straight line and do not bend with the curvature of the earth. Slide 27

Types of Communication Media Communication Satellites It is typically used for transmission in large, geographically dispersed organizations that would be difficult to network using cabling media or terrestrial microwave. It can transmit data over longer distances without the problem of curvature of the earth. Cellular Systems It uses radio waves to communicate with radio antennas placed within adjacent geographic areas called cells. Communications transmitted from a cell phone to a local cell pass from antenna to antenna until they reach their final destination. Slide 28

Topic Four TRENDS IN TELECOMMUNICATIONS Slide 29

Trends in telecommunications Major trends occurring in the field of telecommunications have a significant impact on management decision in this area. The major trends are; Industry trend, Technology trend and Business Application trend. Industry Trends The telecommunications industry has changed from government-regulated monopolies to a deregulated market with fiercely competitive suppliers of telecommunications services. Slide 30

Trends in telecommunications Companies now offer businesses and consumers a choice of everything from local and global telephone service to communications satellite channels, mobile radio, cellular phone services and Internet access. The explosive growth of the internet and the web has spawned a host of new telecommunication products, services, and providers. Businesses have dramatically increased their use of the Internet and the Web for electronic commerce and collaboration. Slide 31

Trends in telecommunications Technology Trends Change from reliance on copper wire-based media and land-based microwave systems to fiber-optic lines, communication satellites and other wireless technologies. Increase in client/server networks. Moving from analog to digital network technologies. Slide 32

Trends in telecommunications Business Application Trends Cut cost. Shorten business lead times and response times. Support electronics commerce. Improve the collaboration of workgroups. Develop online operational processes. Develop new products and services. Slide 33

References French, C. S. (2001). Data processing and information technology (10th ed.). London, Continuum: Sage Publications Ltd. Hutchinson, S. E., & Sawyer, S. C. (2000). Computers, communication and information: A user s introduction (7th ed.). Boston: Irwin McGraw-Hill. O Leary, T. J. (2004). Computing today. Boston: McGraw Hill. O Leary, T. J., & O Leary, L. I. (2005). Computing Essentials. Boston: McGraw Hill. Thompson, R. L., & Cats-Bail, W. L. (2003). Information technology and management (2nd ed.). Boston: Irwin McGraw- Hill. Williams, et al (2003). Using information technology: a practical introduction of computers and communications. Boston: McGraw-Hill. Slide 34