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Communication systems v5


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Communication systems v5

  1. 1. Communications Systems By Dr. Muhammad Saleem Awan
  2. 2. twisted-pair cable twisted-pair wire
  3. 3. UTP Categories • Cat 1 – Used for audio frequencies, speaker wire, etc. Not for networking. • Cat 2 – Up to 1.5Mhz, used for analog phones, not for networking • Cat 3 – EIA 568-A Spec from here on up – up to 16MHz – Voice grade found in most offices – Twist length of 7.5 cm to 10 cm • Cat 4 – up to 20 MHz – Not frequently used today, was used for Token Ring
  4. 4. UTP Categories Cont. • Cat 5 – up to 100MHz – Twist length 0.6 cm to 0.85 cm – Commonly pre-installed in new office buildings • Cat 5e “Enhanced” – Up to 100Mhz – Specifies minimum characteristics for NEXT (Near End Crosstalk) and ELFEXT (Equal level far end crosstalk) • Coupling of signal from one pair to another • Coupling takes place when transmit signal entering the link couples back to receiving pair, i.e. near transmitted signal is picked up by near receiving pair • Cat 6 – Proposed standard up to 250Mhz • Cat 7 – Proposed standard up to 600Mhz
  5. 5. plastic outer coating woven or braided metal insulating material copper wire
  6. 6. protective coating glass cladding optical fiber core Optical FiberOptical Fiber An optical fiber is a thin (2 to 125µm), flexible medium capable of guiding an optical ray. Preferable because of, • Large bandwidth, light weight, and small diameter • Nonconductivity (no EMI & RFI) • Longer distance signal transmission with lesser attenuation • Security & greater repeater spacing • Designed for future applications needs
  7. 7. Optical FiberOptical Fiber Five basic categories of application have become important for optical fiber: • Long-haul trunks • Metropolitan trunks • Rural exchange trunks • Subscriber loops • Local area networks
  8. 8. Basic fiber optic communication systemBasic fiber optic communication system
  9. 9. Transmission WindowsTransmission Windows • Optical fiber transmissions uses wavelengths in the near infrared portion of the spectrum • Both Lasers and LEDs are used to transmit light through fibers • Lasers are used for 1310 nm or 1550 nm single mode transmissions • LEDs are used for 850- or 1300 nm multimode applications
  10. 10. Fiber Optic Loss CalculationsFiber Optic Loss Calculations
  11. 11. Fiber Optic TypesFiber Optic Types • Step-index multimode fiberStep-index multimode fiber – the reflective walls of the fiber move the light pulses to the receiver • Graded-index multimode fiberGraded-index multimode fiber – acts to refract the light toward the center of the fiber by variations in the density • Single mode fiberSingle mode fiber – the light is guided down the center of an extremely narrow core Three basic types of optical fibers are used in communication systems
  12. 12. Optical Fiber Transmission CharacteristicsOptical Fiber Transmission Characteristics Optical Fiber Transmission Modes
  13. 13. Optical Fiber Transmission CharacteristicsOptical Fiber Transmission Characteristics
  14. 14. Components - Optical Fiber CableComponents - Optical Fiber Cable
  15. 15. Components - Optical Fiber CableComponents - Optical Fiber Cable
  16. 16. Indoor Optical Fiber CableIndoor Optical Fiber Cable
  17. 17. Outdoor Optical Fiber CableOutdoor Optical Fiber Cable
  18. 18. Next Lecture TopicsNext Lecture Topics Topics include, •Dispersion in optical fiber •Multiplexing •Fiber Optic Sources •Fiber Optic Detectors •Fiber Optic System Design Considerations