PPT On The Physical Layer

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The Physical Layer Presentation Transcript: 
1.The Physical Layer

2.The Theoretical Basis for Data Communication
Fourier Analysis
Bandwidth-Limited Signals
Maximum Data Rate of a Channel

3.Bandwidth-Limited Signals

4.Guided Transmission Data
Magnetic Media
Twisted Pair
Coaxial Cable
Fiber Optics

5.Twisted Pair

6.Fiber Optics
Three examples of a light ray from inside a silica fiber impinging on the air/silica boundary at different angles.
(b) Light trapped by total internal reflection.

7.Transmission of Light through Fiber

8.Fiber Cables
(a) Side view of a single fiber.
(b) End view of a sheath with three fibers.

9.Wireless Transmission
The Electromagnetic Spectrum
Radio Transmission
Microwave Transmission
Infrared and Millimeter Waves
Lightwave Transmission

10.The Electromagnetic Spectrum

11.Radio Transmission
(a) In the VLF, LF, and MF bands, radio waves follow the curvature of the earth.
(b) In the HF band, they bounce off the ionosphere.

12.Politics of the Electromagnetic Spectrum

13.Lightwave Transmission
Convection currents can interfere with laser communication systems. 
A bidirectional system with two lasers is pictured here.

14.Communication Satellites
Geostationary Satellites
Medium-Earth Orbit Satellites
Low-Earth Orbit Satellites
Satellites versus Fiber

15.Communication Satellites
Communication satellites and some of their properties, including altitude above the earth, round-trip delay time and number of satellites needed for global coverage.