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Transmission Media II (06.523)

Transmission Media II (06.523)

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Transmission Media II (06.523)

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  1. Transmission Media II (06.523) Types and properties of physical transmission media II

  2. Characteristics and limitations • Memorise table from workbook :-(

  3. Electrical signalling • Analogue signals on analogue networks • Digital signals on digital networks • Digital signals on analogue networks • Analogue signals on digital networks

  4. Connection standards • ITU-TSS (International Telegraph Union - Telecommunications Standardisation Sector) • V. series (DTE to PSTN) • X. series (DTE to Public Digital Data Network) • I. Series (DTE to Integrated Service Digital Network)

  5. Control lines • Purpose • Typical lines

  6. Example: RS232-C 25 pin • 1. Shield • 2. Transmitted Data (TXD) • 3. Received Data (RXD) • 4. Request to Send (RTS) • 5. Clear to Send (CTS) • 6. DCE Ready (Data cable enable?) • 7. Signal ground • …

  7. Example: RS232-C 9 pin • 1. Carrier Detect (CD) • 2. Receive Data (RXD) • 3. Transmit Data (XD) • 4 Data Terminal Ready (DTR) • 5. Signal Ground (SG) • 6. Data Set Ready (=DCE) • 7. Request To Send (RTS) • 8. Clear To Send (CTS) • 9. Ring Indicator (RI)

  8. Signal attenuation • What is it • Why is it important • Types of errors • extra bits • missing bits • flipped • set to zero/one

  9. Common causes • White noise (unavoidable) • Impulse noise or spikes • Cross talk from multiplexing • Intermodulation noise from interference • Echoes from inadequate termination • Attenuation from too long cables • Delay distortion (Sync. Freq. timings) • Jitter (Imperfect digital -> analogue) • Line outage

  10. Error prevention • Shielding • Moving cables • Changing multiplexing (cross talk) • Improving connection quality • Amplifiers • Equaliser (syncs freq. timings) • Conditioning (certified)