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Physical Layer. Computer Networks. Where are we?. Numbering Systems. Binary Hexadecimal Decimal. Transmission of Information. From Physics Energy Electromagnetic wave propogation From Mathematics Coding Theory. Analog and Digital Signaling. Amplitude Modulation. Frequency Modulation.
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Physical Layer Computer Networks
Numbering Systems • Binary • Hexadecimal • Decimal
Transmission of Information • From Physics • Energy • Electromagnetic wave propogation • From Mathematics • Coding Theory
Undesirable Effects and Limitations • Propagation Delay • Bandwidth • Noise • Interference • Distortion • Attenuation
Shannons Limit • Corrects for SNR • Encoding more bits per cycle time helps, but you cannot overcome the fundamental physical limits of a real transmission system.
Timing • Asynchronous • bit level • Synchronous • character level • Isochronous • timing coordination must be successful
Media Test and Measurement • Hands-on Demo
Repeaters • Signal Regeneration • Clean up • Amplifly • Distance Extension
Hubs • Repeater functionality, plus... • Concentration Point • Signal Distribution Device • Management Functions
Electrical Property Determined by physics Throughput versus Bandwidth • Usable capacity • Determined by engineering