1

Physical Layer

Computer Networks

2

Where are we?

3

Numbering Systems

BinaryHexadecimalDecimal

4

Transmission of Information

From PhysicsEnergyElectromagnetic wave propogation

From MathematicsCoding Theory

5

Analog and Digital Signaling

6

Amplitude Modulation

7

Frequency Modulation

8

Baseband and Broadband

9

Phase Modulation

10

Modems

11

Digital Encoding

12

CSU/DSU

13

Undesirable Effects and Limitations

Propagation DelayBandwidthNoiseInterferenceDistortionAttenuation

14

Sampling and Nyquist’s Theorem

15

Shannon’s Limit

Corrects for SNR

Encoding more bits per cycle time helps, but you cannot overcome the fundamental physical limits of a real transmission system.

16

Timing

Asynchronousbit level

Synchronouscharacter level

Isochronoustiming coordination must be successful

17

Transmission Media

18

Connectors

19

Media Test and Measurement

Hands-on Demo

20

Repeaters

Signal RegenerationClean upAmpliflyDistance Extension

21

Hubs

Repeater functionality, plus...Concentration PointSignal Distribution DeviceManagement Functions

22

Throughput versus Bandwidth

Usable capacityDetermined by

engineering

Electrical PropertyDetermined by

physics