L4LongDist6 - Part 1 Data Transmission Part 1 Data...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Part 1 – Data Transmission Long-Distance Communication - Carriers and Modems Gail Hopkins Part 1 – Data Transmission Introduction ± Sending signals over long distances ± Modems ± Leased serial data circuits ± Optical, radio and dialup modems ± Multiplexing ± DSL and Cable modems Part 1 – Data Transmission Signalling Across Long Distances ± Resistance in wires => signal loss => current cannot be propagated over long distances ± A continuous oscillating signal will propagate further than other signals Part 1 – Data Transmission Modulation ± Send an oscillating carrier wave and then modulate it in some way ± Technique originated with radio and TV (stations use different carrier frequencies) ± Transmitter generates carrier and modulates according to data, receiver discards carrier ± Two approaches from radio are frequency modulation (FM) and amplitude modulation (AM) Part 1 – Data Transmission Amplitude Modulation (AM) ± Change amplitude of the carrier according to the data Part 1 – Data Transmission Frequency Modulation (FM) ± Slightly change frequency of the carrier according to the data
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Part 1 – Data Transmission Phase Shift Keying (PSK) ± FM and AM require at least one wave cycle to send a bit ± Phase shift changes the timing of the carrier and can send several bits per cycle Part 1 – Data Transmission
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/14/2011 for the course ELECTRONIC G52CCN taught by Professor Professorgail during the Spring '09 term at Uni. Nottingham.

Page1 / 4

L4LongDist6 - Part 1 Data Transmission Part 1 Data...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online