Transcript PPT

Part I
Signals, Media, And
Data Transmission
CSI 4118
Fall 2002
1
Transmission of Information


Well-understood basics
From physics



Energy
Electromagnetic wave propagation
From mathematics

CSI 4118
Coding theory
Fall 2002
2
Transmission Media

Copper wire



Optical fiber



Need two wires
Possibilities
 Twisted pair
 Coaxial cable
Flexible
Light “stays in”
Air / space

CSI 4118
Used for electromagnetic transmission
Fall 2002
3
Forms of Energy Used
To Transmit Data



Electric current
Audible sounds
Omni-directional electromagnetic waves


CSI 4118
Radio Frequency (RF)
Infrared
Fall 2002
4
Forms of Energy Used to
Transmit Data (continued)

Directional electromagnetic waves




CSI 4118
Point-to-point satellite channel
Limited broadcast (spot beam)
Microwave
Laser beam
Fall 2002
5
Types of Satellites


Geosynchronous Earth Orbit (GEO)
Low Earth Orbit (LEO)

CSI 4118
Array needed
Fall 2002
6
Two Important Physical Limits
Of a Transmission System

Propagation delay



Time required for signal to travel across media
Example: electromagnetic radiation travels
through space at the speed of light (c = 3*108
meters per second)
Bandwidth

CSI 4118
Maximum times per second the signal can change
Fall 2002
7