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Transmission Media

Transmission Media. Engr. M Jamil Khan. Outline. Twisted Pair: Introduction to Telephone Wire Unshielded Twisted Pair (UTP) Shielded Twisted Pair (STP) Coaxial Cable Microwave Radio Satellite Radio Infrared Fiber Optics. Twisted Pair. Two Copper conductors.

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Transmission Media

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  1. Transmission Media Engr. M Jamil Khan

  2. Outline • Twisted Pair: Introduction to Telephone Wire • Unshielded Twisted Pair (UTP) • Shielded Twisted Pair (STP) • Coaxial Cable • Microwave Radio • Satellite Radio • Infrared • Fiber Optics

  3. Twisted Pair Two Copper conductors. Separately Insulated (avoid short circuit). Both conductors serve for signal transmission and reception. A Balanced medium.

  4. Twisted Process The separately insulated couple twisted 90 degree at routine, specified interval, hence the twisted pair. This process of improves the performance of medium by containing the electromagnetic energy within the pair. The more twists per foot, the better performance of wire.

  5. Types of Twisted Pair There are two types of twisted pair cables Unshielded Twisted Pair Shielded Twisted Pair

  6. Unshielded Twisted Pair The most common form of copper wire used in communications is Unshielded twisted Pair (UTP), which has no shield to protect the signal from outside sources of electromagnetic interferences.

  7. Unshielded Twisted Pair

  8. Gauge Gauge is measure of thickness of a conductor. The thicker the wire, the less the resistance, the stronger the signal over distance, and better the performance of the medium. Thicker wire also offer the advantage of break strength. The gauge numbers are retrogressive.

  9. Categories (UTP)

  10. Configuration (UTP) In single pair configuration, the pair of wires is enclosed in a jacket or sheath. Multiple pairs are bundled in a single sheath to minimize the deployment cost. Large number of pairs are bundles to serve departments such cables may contain 25, 50, 100 pair of wires.

  11. Bandwidth (UTP) • The effective capacity of twisted pair cable depends on • Gauge of conductor. • Length of circuit. • Spacing of amplifiers.

  12. Error Performance(UTP) Signal quality always important especial relative to data transmission. UTP is prone to the impacts of outside of interferences. Potential sources of Electromagnetic interference (EMI) and Radio frequency interferences (RFI) are electric motor, radio transmissions, and fluorescent light boxes.

  13. Distance (UTP) • UTP contains some distance limitations. • Analog voice transmissions require amplifiers spaced at least every 2-4 miles. As a result Local loops are generally 10000-18000 in length. • T-1 transmission requires repeater at the interval of 6000 ft.

  14. Security (UTP) UTP is an insecure transmission medium.

  15. Cost (UTP) The acquisition, deployment and rearragement costs of UTP are very low. In high capacity, long distance applications (e.g. interoffice trucking), the relative costs are very high.

  16. Applications (UTP) Short haul distribution systems Inside applications Local loop

  17. Shielded Twisted Pair Shielded twisted pair (STP) differs from (UTP) in that a metallic shields or screen surrounded the pairs which may or may not be twisted. The pairs can be individually shielded or a single shield surround by the cable containing multiple pairs or both techniques cab be employed in tandem.

  18. Shielded Twisted Pair

  19. Shielded Twisted Pair • Shielded twisted pair (STP) offers advantages of enhanced performances, for reason of • Reduced emission. • Reduction of electromagnetic interferences, the shield absorbs the energy and conducts it to ground.

  20. Applications (STP) • The additional cost of shielded copper limited its classic application to inside wire in high noise environment. • It also deploy • High frequency signals are transmitted. • Interference with adjacent pair presents.

  21. Coaxial Cable Coaxial cable is a very robust shielded copper wire. The center conductor is much thicker than a twisted pair conductor, and is surrounded by an outer shield/conductor that serves to greatly improve signal strength and integrity. A layer of foam or solid insulation generally separates the two conductors. The cable is then protected by a layer of dielectric material. The two conductors share a common axis, hence the term coaxial.

  22. Coaxial Cable

  23. Configuration

  24. Gauge Coaxial cable gauge is much thicker than twisted pair, as a result it increases the bandwidth and distance of transmission. It also increases the cost.

  25. Error Performance Coaxial cable offer excellent error performance due to the outer shield. However end to end integrity of shield is crucial, either physical damage or poor splicing will result in awful error performance. The shield also must be ground properly.

  26. Distance Coax have not same distance limitation as twisted pair. It can carry high frequencies on significant distances.

  27. Security More secure than UTP. It is not easy to tape coax.

  28. Cost The acquisition, deployment and rearrangement of coax are very high compared with UTP, due to increase bulk and weight, as well as requirement of ground for outer shield.

  29. Applications • Historically, coax was used in Telco interoffice trucking. • Coax extensively used in cable TV networks. • 330 MHz 40 channels • 750 MHz 116 Channels

  30. Microwave Radio Microwave radio, a form of radio transmission which uses ultra-high frequencies, developed out of experiments with radar during the period preceding World War ll. There are several frequency ranges assigned to microwave systems, all in the Gigahertz (GHz) range – in other words, billions of cycles per second. Wavelength in millimeter range.

  31. Configuration Microwave radio consists ofantennae centered within reflective dishes, which are attached to structures such as towers or buildings and generally take the shape of either a parabola (bowl) or horn (cornucopia). Hollow cables or tubes, known as waveguides, serve to guide the radio microwaves between the electronic transmit/receive equipment and antennae.

  32. Bandwidth • Microwave offers significant bandwidth, often in excess of 6Gbps. • T-1 (1.544 Mbps) is routine. • T-3 (45 Mbps) also used in private networks.

  33. Error Performance Microwave especially digital performs well in error performance – assuming proper design and deployment. Environmental interferences greatly effect especially frequencies above 8 GHz.

  34. Distance Microwave is distance limited

  35. Security Microwave radio is an insecure media. If microwave path is known, a radio antennae can capture the raw signals. Security must be imposed though encryption of signal.

  36. Cost The acquisition, deployment and rearrangement costs of microwave are very high. However it can be compared with cable systems.

  37. Regulations Microwave must be licensed case by case basis to avoid interferences among adjacent systems.

  38. Applications Microwave used for long haul voice and data communications.

  39. Satellite Radio Satellite radio is microwave transmission system utilizing non-terrestrial relay station positioned in space. Satellite have proved invaluable in extending the reach of voice, data and video communication around the globe and in the most remote region of the world.

  40. Satellite Radio

  41. Satellite Radio • Key term • Uplink • Downlink • Footprint (Coverage Area) • GEO (Geostationary Earth Orbit) • MEO (Medium Earth Orbit) • LEO (Low Earth Orbit)

  42. Satellite Radio

  43. Satellite Radio

  44. Configuration Antenna and Reflective dishes accompanied with waveguides to transceiver electronic equipment on earth stations. The space segment antenna mounted on satellite. Satellite have multiple transceiver antenna depending upon various frequencies to support various applications.

  45. Bandwidth

  46. Error Performance Satellite transmission is susceptible to environmental interference, particularly at frequencies above 20 GHz. Sunspots and other types of electromagnetic interference particularly impact satellite and microwave transmission. So satellite transmission requires rather extensive error detection and correction capabilities.

  47. Distance Satellite is not consider to be distance limited. Each signal travels approximatelly 22000 miles in each direction

  48. Security Satellite is an insecure medium. For secure transmission , encryption must be enforced.

  49. Cost The acquisition, deployment and rearrangement cost is quite high.

  50. Applications • Satellite Application are many, some are • GPS global positioning system • ATMS advance traffic management system • Direct Broadcast Satellite (DBS) TV • Mobile voice and date (LEO and MEO) • Internet access

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