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  1. Communications Theory Parallel vs. serial transmission Transmission Capacity (Shannon) Error detection and correction Communications Media Optical fibers Coaxial cables Twisted pairs Wireless Contents

  2. sin 1 sin 2 n2 n1 = Snell’s Law 2 n2 n2 n2  n1 n1 n1 c >c 1 n2 < n1

  3. Optical Fibers(step index) n2 < n1 n2 n1 Protective coating

  4. Multimode Fiber Diameter : > 50  Step index fiber Graded index fiber Low cost but limited bandwidth * distance due to multimode dispersion

  5. Multimode Dispersion t t Step index fiber : < 50 MHz.Km Graded Index Fiber : < 1000 MHz.Km (1990) < 5000 MHz.Km (2000)

  6. Monomode Fiber Diameter : < 5  Only one propagation mode possible Higher cost due to end equipment but enormous bandwidth*distance product 10 Gb/s over 500 Km optical sections (1995)

  7. Wave Domain Multiplexing Each color can carry an independent data flow. In 2000 40 colors carrying each 10 Gb/s or 80 colors carrying each 2.5 Gb/s were commercially available

  8. Optical amplifiers Pump laser Erbium doped fiber Erbium atoms are pumped into a higher energy state by the light of the pump laser, they fall back in synchronism with the incoming light, amplifying it.

  9. Optical Switching From IEEE Com.Mag.V39,N1, Jan 2001.

  10. Communications Theory Parallel vs. serial transmission Transmission Capacity (Shannon) Error detection and correction Communications Media Optical fibers Coaxial cables Twisted pairs Wireless Contents

  11. Coaxial Cables Insulator Conductor Conductor Protective coating Monomode propagation for all data applications Transmission rates up to some Gb/s Distance limited by electrical attenuation

  12. Communications Theory Parallel vs. serial transmission Transmission Capacity (Shannon) Error detection and correction Communications Media Optical fibers Coaxial cables Twisted pairs Wireless Contents

  13. Twisted Pairs Performance highly dependant on cable quality Transmission speed up to several 100 Mb/s for distances of up to 100 m. with better cables (class 5 or 6)