Telecommunications and Networks Chapter 8 Types of Signals

Telecommunications and Networks Chapter 8

Types of Signals Analog – a continuous waveform that passes through a communications medium n Digital signal is a discrete waveform. It transmits data coded into two discrete states: 1 -bits and 0 -bits. n

Modem n Translate a computer’s digital signals into analog form for transmission over ordinary telephone lines, or it translate analog signals back into digital form for reception by a computer

Transmission media Twisted wire n Coaxial cable n Fiber optics n Terrestrial microwave n Satellite n Wireless transmission n

Transmission speed Bit per seconds – total amount of information that can be transmitted through any telecommunications channel n 56 Kilo bit per second for current modem n

Bandwidth The difference between the highest and lowest frequencies that can be accommodated on a single channel n The greater the range of frequencies, the greater the bandwidth and the greater the channel’s transmission capacity n

LAN Local Area Network n Encompasses a limited distance, usually one building or several buildings in close proximity n Used to connect PCs in an office to shared printers and other resources n

Servers May be powerful PCs with large hard -disk capacity, workstations, midrange computer, or mainframe n Some specialized computers are used for network connections n

Gateway Generally a communication processor that can connect dissimilar networks by translating from one set of protocols to another. n The network gateway connects the LAN to public networks, such as the internet n

Router n Is used to route packets of data through several connected LANs or a wide area network

WAN Wide area network n Span broad geographical distances, ranging from several miles to entire continents n

DSL Digital Subscriber line n Operate over existing copper telephone lines to carry voice, data, and video, but they have higher transmission capacities n

Cable modems Modems designed to operate over cable TV lines n Provide high speed access to the Web or corporate intranets of up to 4 megabits per second n

T 1 line A dedicated telephone connection comprising 24 channels that can support a data transmission rate of 1. 544 megabit per second n Are used for high-capacity internet connections n

TCP/IP Transmission Control Protocol / Internet Protocol n Developed by US department of Defense in 1972 n Become Internet standard n OSI (Open Systems Interconnect) is another transmission model n

Management Issues New Way of life n Managing the changes n Planning for connectivity, bandwidth, and reliability n Security and privacy n