Physical Aspects of Data Communication: Media

Main Objectives To describe different media To compare data comm media To select media appropriateness To describe signals, explain modem functions and; –Channel service unit (CSU) –Data Service Unit (DSU)

Major Classes of Data Comm Media Also referred to as transmission Conducted Radiated

Conducted Media Wires –Advantages –Disadvantages Private versus Public Lines Transmission Speed and Frequency Range Cables –Cost, gauge, and types

Switched Connections versus Leased Lines Definitions –Switched –Leased –Conditioning Telephone example

Twisted Pair AWG rating- measure of thickness of copper in cable –The higher the number the _____ the diameter? UTP versus STP –What do they mean and which is better? CAT 1, CAT 2, CAT 3, CAT 4, CAT 5 RJ-45 Connector Costs, CrossTalk, and Attenuation See Table 2-2, Figure 2-5

Coaxial Cable Used over short distances (about 10 miexcept for ???) Broadband transmission –guardband Baseband Transmission Advantages and Disadvantages

Fiber Optic Cable Comes in three technologies –Multimode step-index fiber Oldest technology where reflective walls of fiber move light pulse to the receiver –Multimode graded-index fiber Fiber if REFRACTED towards center by variations in density of the core –Single-mode transmission Fastest fiber optic technique, where light is guided down the center of an extremely narrow core Advantages/Disadvantages The new question whether fiber or coaxial cable?

Radiated Media Broadcast Radio –AM/FM radio Mobile computing Microwave Radio Satellite Advantages/Disadvantages Geosynchronous Orbit