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Thought of the Day

Thought of the Day.

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Thought of the Day

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  1. Thought of the Day [The mother] of a young piano student, wishing to encourage him, bought tickets for a performance of the great Polish pianist, Paderewski. The night of the concert arrived and the mother and son found their seats near the front of the concert hall. While the mother visited with friends, the boy slipped quietly away. Suddenly, it was time for the performance to begin and a single spotlight cut through the darkness of the concert hall to illuminate the grand piano on stage. Only then did the audience notice the little boy on the bench, innocently picking out “Twinkle, Twinkle, Little Star”. His mother gasped, but before she could move, Paderewski appeared on stage and quickly moved to the keyboard. He whispered to the boy, “Don’t quit. Keep playing.” And then, leaning over, the master reached down with his left hand and began filling in the bass part. Soon his right arm reached around the other side, encircling the child, to add a running obbligato. Together, the old master and the young novice held the crowd mesmerized. IT 327 - Schweber Chap 18

  2. Thought of theDay, cont’d In our lives, unpolished though we may be, it is the Master who surrounds us and whispers in our ear, time and time again, “Don’t quit. Keep playing.” And as we do, He augments and supplements until a work of amazing beauty is created. He is right there with all of us, telling us over and over, “Keep playing.” Pres. James E. Faust 2nd Counselor, First Presidency Nov 1999 Ensign, p. 101 IT 327 - Schweber Chap 18

  3. Schweber, Chap 18: Local and Wide Area Networks; Special-Purpose Links IT 327 - Schweber Chap 18

  4. Networking: Topologies One-to-All Star Bus Ring IT 327 - Schweber Chap 18

  5. Networking: Topologies, cont’d IT 327 - Schweber Chap 18

  6. Networking: Protocols IT 327 - Schweber Chap 18

  7. Networking: Protocols IT 327 - Schweber Chap 18

  8. Networking: Tolkien Ring IT 327 - Schweber Chap 18

  9. Networking: AdvancedProtocols IT 327 - Schweber Chap 18

  10. Networking: ThexANs IT 327 - Schweber Chap 18

  11. Ethernet: High-SpeedStuff IT 327 - Schweber Chap 18

  12. Networking: TheStack (Layers) IT 327 - Schweber Chap 18

  13. Networking: TheStack (Layers) IT 327 - Schweber Chap 18

  14. Networking: AdvancedProtocols IT 327 - Schweber Chap 18

  15. Special Networks • Small Computers System Interface (SCSI) • 50 Mbps, 1984; Ultra-5: 640 Mbps (2003) • iSCSI: Ethernet/network dependent • Universal Serial Bus (USB) • v. 1.0: 12 Mpbs; 1994; v. 2.0: 480 Mbps; 2000; v. 3.0: 4.8 Gbps (2009) • Firewire (IEEE 1394; AppleTalk) • 400 Mbps; 1996; 800 Mbps (2006); declining • Thunderbolt • 10 Gbps; 4 lanes, differential, 5.4 Gbps/lane; 15 ft (5m) with copper; 100 m with MMF; Both PCI-e and DisplayPort • ATA (Advanced Technology Attachment • 1064 Mbps over 16 parallel differential lines (40 conductors) • SATA (Serial ATA) • 1.o = 1.5 Gbps over 2 paris; 2.0 = 3 Gbps; 3.0 = 6 Gbps (same cable) IT 327 - Schweber Chap 18

  16. Networking: QoS IT 327 - Schweber Chap 18

  17. Networking: QoE IT 327 - Schweber Chap 18

  18. Spread-SpectrumSystems Frequency-Hopping Spread Spectrum (FHSS) IT 327 - Schweber Chap 18

  19. Spread-SpectrumSystems Direct-Sequence Spread Spectrum (DSSS) IT 327 - Schweber Chap 18

  20. Spread-SpectrumSystems Advantages Looks like noise Cannot be received without key (PRBS pattern) Extremely difficult to jam Can accommodate n orthogonal signals & n*p non-orthogonal signals, where p = degree of non-orthogonality (from >1 to 10 or more) Disadvantages Very complicated circuitry IT 327 - Schweber Chap 18

  21. Power Line Communications Primer • Developed over 40 years ago • Major problems with attenuation • 10-30 dB/km on LV lines • 100 dB/km on MV, HV lines • Transformers even worse • Massive amounts of noise, both online and emitted • X10 uses ASK, 20 bps • Modern systems use OFDM • HPAV (Home Plug AV) capable of 200 Mbps gross, 150 Mbps net; 500 Mbps and 1 Gbps expected • Turbo convolutional FEC • MIMO (both “hot” and “neutral”) IT 327 - Schweber Chap 18

  22. Power Line Communications Primer, p. 2 • Apps in line metering, Smart Grid control, HANs • Other high-speed standards: • HomePNA • MoCA • UPA (Spanish) • G.hn (ITU standard) • IEEE P1905 (interoper-ability between Wi-Fi, Ethernet, MoCA) • Many NB (low speed) standards • IEC 61334 • IEEE 1901.2 • HomePlug Green PHY • G3 • PRIME • G.hnem • Common approaches: • OFDM, 8PSK, DQPSK, RS FEC, CRC IT 327 - Schweber Chap 18

  23. Shannon’sLaw, Revisited A ───→Noise=275 µW; Attenuation=46dB (wattage) ───→ B Tx power = 50 dBmFind: 1. Rx power (mW) Tx channel = 964-972 MHz 2. Rx SNR (dB) 3. Capacity (Mbps) IT 327 - Schweber Chap 18

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