1 Tangible Media (Cables) Coaxial –Thinwire –Thickwire Twisted Pair (UTP and STP) Fiber Optic Cable

2 Intangible Media Wireless –Create temporary connections into wired networks –Establish back-up (contingency) for wired –For roaming mobile users –Frequencies Radio 10Khz – 1Ghz Microwave 1Ghz – 500 Ghz Infrared 500Ghz – 1 Thz

3 Cable Characteristics Maximum transmission rate using Shannon law Maximum segment length –How far can a signal travel before it weakens (attenuation) Maximum number of segments –Amount of time for a signal to travel from one end of cable to another Maximum number of devices on a segment –Insertion loss causes attenuation Interference –Electrical motors (other signals)

4 Comparison of different media Max Cable Length Typical Transmission Speed InterferenceCost Coax Thinwire 186m- 607’ 10MbpsGoodCheap Coax Thickwire 500m- 1640’ 10MbpsBetterModerate UTP100m – 328’ 100MbpsBadCheapest Fiber2-100 km 6562’- 62mi 1GbpsNoneExpensiv e

5 Baseband vs Broadband See page 93 of text Broadband –A type of data transmission in which a single medium (wire) can carry several channels at once. Cable TV, for example, uses broadband transmission. In contrast, baseband transmission allows only one signal at a time. mediumchannelsbaseband transmission –Most communications between computers, including the majority of local-area networks, use baseband communications.communicationscomputerslocal-area networks

6 Baseband vs Broadband Baseband –A type of digital data transmission in which each medium (wire) carries only one signal, or channel, at a time. In contrast, broadband transmission enables a single wire to carry multiple signals simultaneously.digitaldatamedium channelbroadband transmission –Most communications involving computers uses baseband transmission. This includes communications from the computer to devices (printers, monitors, and so on), communications via modems, and the majority of networkscommunicationscomputersdevicesprintersmonitorsmodemsnetworks

7 Two Uses for Term “Broadband” Broadband – channel band width is wide –More bandwidth means higher speeds by Shannons Law –Many companies now call high speed access Broadband ( although it may be only 1 channel using baseband) –Call multi channels broadband