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SHIELDED CABLE PERFORMANCE PARAMETERS

SHIELDED CABLE PERFORMANCE PARAMETERS. NETWORK CABLE SOLUTIONS MODULE 2-J. SCREEN TECHNOLOGY. Screening of UTP cables Shielded Screened or Foiled Known as ScTP in the Americas. Low usage Known as FTP in Europe 80 % of installed LAN’s Primarily in UK, France, Germany. SCREEN TECHNOLOGY.

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SHIELDED CABLE PERFORMANCE PARAMETERS

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  1. SHIELDED CABLE PERFORMANCEPARAMETERS NETWORK CABLE SOLUTIONSMODULE 2-J

  2. SCREEN TECHNOLOGY • Screening of UTP cables • Shielded Screened or Foiled • Known as ScTP in the Americas. • Low usage • Known as FTP in Europe • 80% of installed LAN’s • Primarily in UK, France, Germany

  3. SCREEN TECHNOLOGY • Advantages • Greater immunity from RFI/EMI interference. • Yields lower bit error rate. • Greater immunity from radiated signals. • Yields a more secure cabling solution. • Disadvantages • Higher installed cost • Material and Labor • Greater difficulty in installation • Shorter link lengths under certain conditions

  4. SCREENED TECHNOLOGY • Two basic construction • FTP (ScTP) • Four pair cable with an overall foil shield. • Drain Wire • S-FTP • Four pair cable with individually pairs. • Overall braided shield. • Drain Wire • Similar to the STP cables used in Token Ring applications.

  5. SCREENED TECHNOLOGY • 100 ohm Shielded cabling Design • Not 100 Ohm UTP with a shield. • Shielded 100 Ohm twisted pair is designed to provide certain system performance characteristics • It can have a large number of variations.

  6. STANDARDS • TIA/EIA 568-A • Has references to 4 pair, 100 ohm shielded cable • It is allowed if it meets the same performance specifications as UTP. • No description of cable construction. • No specifications on the connector shield interface. • No specifications on shielding performance. • No guideline on how to design or install a system in order to maintain shielding performance

  7. STANDARDS • TIA Task Group • Formed to fill the gaps and define specific. • Component Requirements. • Installation Requirements. • Task Group Definition • 4 pair to be used as a standard. • Overall foil shield and drain wire to be the basic construction. • Other shields and braids may be added as long as basic construction is maintained.

  8. STANDARDS • TIA Task Group • Task Group Definitions • Performance categories are the same as for UTP. • Color coding is the same. • 8 position jack is maintained. • Jack to plug shield has been standardized and a test has been developed to verify shielding performance of a mated pair. • Requirements for shield continuity and grounding have been determined.

  9. STANDARDS • ISO/IEC 11801 • More complete than TIA EIA 568A, but has gaps. • List tentative specifications on cable and connector shielding performance. • Provides basic installation guidelines on shield continuity and grounding. • Allows both 2 pair and 4 pair. • Allows 120 ohm impedance.

  10. STANDARDS • ISO/IEC 11801 • Allows both: • Overall shield construction • Individually Shielded Construction • EN 55022 • This directive defines the limits and methods of measurement of ratio frequency interference characteristics of information technology equipment. • Limits on what a LAN can emit. • Similar to limit imposed by the FCC in the U.S.

  11. STANDARDS • EMC & Cabling Systems • Unshielded or badly shielded cable cannot pass the European emissions directive at much more than 30 Mhz without encoding schemes or filter devices. • The FCC in the United States limits the transmission frequency at 30 Mhz • Through encoding schemes transmission at 31.25 Mhz is possible because it spreads the energy over a wider frequency.

  12. SHIELDING EFFECT • Emissions • Screens reduce the radiated signals by a minimum of 20 dB.

  13. STANDARDS • EN 55024 • Defines the degree of sensitivity of a system with regard to the following: • Electrostatic Discharge Immunity, Part 2 • Radiated Immunity, Part 3 • Fast Transient Immunity, Part 4 • Induced Interference, Part 6

  14. POSITION • Strong position in Europe. • In areas where shielded cabling is used. • Reflects concerns over more stringent regulatory controls on electromagnetic emissions. • Concerns regarding interference from electromagnetic noise. • European Community used the term electromagnetic compatibility (EMC) to encompass both concerns.

  15. EMC CONTROL • Shielding is not the only means of EMC control. • Well balanced Non shielded twisted pair cables are effective in limiting emissions and interference at current digital transmission frequencies. • Electronic techniques are used to limit transmission frequencies and maintain acceptable bit error rates in typical office environments.

  16. EMC CONTROL • UTP Cable • EMC control dependent on system balance. • Balance dependent on pair twist rate. • Pair twist rate is close to manufacturing minimum. • Crosstalk performance dependent on variation of twist length. • Ability to further improve crosstalk by twist is limited.

  17. APPLICATION • Emission • Emission standards, when tested, are for “typical” installations which is done in a controlled laboratory environment field installations may be different.. • Cannot cover all installations variables. • Immunity • Influenced by nearby machinery and equipment sources. • Influenced by nearby sources of RFI.

  18. ADVANTAGES OF SHIELDING • Advantages • Take over at point that pair twists leave off and provide electromagnetic interference control at higher frequencies. • Individually shielded cables can provided additional immunity to crosstalk that is not achievable by pair twisting.

  19. APPLICATION • Shielded cables are used to augment EMC characteristics of UTP type cables. • Provide additional control for critical networks. • Additional immunity over eletromechanically noisy environments. • Can be viewed as an additional insurance policy.

  20. LINK LENGTH • Due to the shield a thicker primary insulation is required. • To meet the same attenuation and impedance specifications as that of UTP. • It is impractical to make a 24 AWG patch cord so that it will fit modular jacks. In Europe a 26 AWG cord is allowed. • Attenuation in a 26 AWG cord can be as much as 1.5 times higher than a 24 AWG solid cable. • 24 AWG stranded is 1.2 times.

  21. CONNECTORS • The trend in the United States and most other areas is to standardize on the eight position jack. • Standardized interface to most LAN equipment. • Other connectors available that can utilize that of 24 AWG cable. • Non standard designs.

  22. GROUNDING • Two methods of grounding are currently in use. • Star where one end of the cable is grounded. • Mesh where both ends of the cable are grounded. • The mesh type system may cause ground loops if both grounding points are not at the same ground potential. • The star grounding configuration is recommended.

  23. GROUND LOOPS • Ground Loops if Mesh Grounding is used. • To assure that ground loops do not occur, measure the following between the shield and the green grounding conductor of the outlets servicing the work area. • Resistance should be less than 3.5 ohms. • Voltage should be less than 1 VRMS

  24. PERFORMANCE TESTING • Performance Testing Standards • Recently the ISO/IEC 11801 standardized the performance testing of shielded components in terms of Transfer Impedance. • The TIA TSB will also standardize on this method. • Prior to this manufacturers decided on the method to be used.

  25. SUMMARY • The benefits of a shielded cable system is that it will minimize the variability of installed twisted pair cabling balance and add signal to noise margin.

  26. SHIELDED CABLE PERFORMANCE PARAMETERS QUESTIONS?

  27. FTP CABLE INSTALLATION NETWORK CABLE SOLUTIONSMODULE 2-K

  28. FTP INSTALLATION • Scope • To provide the installer with the guidelines to properly handle high grade FTP cable during installation. • Proper handling assures optimum cable performance for intended present and future applications.

  29. FTP INSTALLATION • Construction • Pairs are twisted more tightly and built to specific design constraints in a Cat. 5 cable. • A precise twist is induced into the bundled 4-Pairs prior to jacketing. • Geometry becomes critical to maintain performance. • Damaging or changing the position of the pairs adversely affects the ability of the cable to carry high data rates.

  30. FTP INSTALLATION • Minimum Bend Radius • Cables exceeding the minimum bend radius will exhibit degraded performance. • Returning flawed section to a larger diameter will not correct the fault. • the cable will still exhibit the degraded transmission performance

  31. FTP INSTALLATION • Minimum Bend Radius • Review conduit bends • Exercise care in installing cable in trays • Do not bend cable over corners • Do not coil cable tightly and stuff into work box. • Store excess coiled in ceiling • Exercise care when dressing cables

  32. FTP INSTALLATION • Minimum Bend Radius • Sweep cables to avoid bends and kinks. • Kinking the cable changes the shape of the core, moves the pairs and changes the geometry • Damage is permanent • Service Loops • 1-3 feet loops at termination points • Leave service loops along the route of the cable

  33. FTP INSTALLATION • Maximum Tensile Loading • Exceeding the maximum tensile loading will adversely affect the performance of the cable. • Quality of the cable is a affected long before damage is visible • Physical stress must be guarded against during installation and in suspended cable runs. • Cables should be well supported. • Correcting cable tension will not reverse the effect of over-loading. • Maximum cable loading for an FTP four pair cable is 25 lb.

  34. FTP INSTALLATION • Over-Cinching • Over-cinching causes compression and distortion of the cable, degrading cable performance. • Cable ties must never distort the jacket. • Avoid using staples • Never crush the cable with staples.

  35. FTP INSTALLATION • Avoid using staples because they crush the cable • The wraps should not distort the jacket of the cable • A properly installed tie wrap can easily be moved up and down and twisted around the bundle

  36. FTP INSTALLATION • Over-Cinching • Select non-compression cable management accessories • Velcro tie wraps • “D” rings • Nail on cable clamps

  37. FTP INSTALLATION • Cable Bundles • Assure that weight of bundle in not compressing cable jacket. • Exert care when running a large cable bundle around a bend • In trays fiber cable should be placed on the top and FTP on the bottom.

  38. FTP INSTALLATION • Cable Lengths • Horizontal runs are limited to 90 meters or less. • Work area equipment cables are limited to 3 m or less. • Patch cords, jumpers, and cross connects are limited to 7 m or less in the telecommunications closet.

  39. FTP INSTALLATION • Other Installation Suggestions • Do not share bore holes with power wires. • Never install components of unknown or questionable manufacture or quality. • Keep wire away from heat sources, heat ducts and pipes. • Leave one to three foot service loops at outlets and connection points. • When existing a cable tray it is recommended that a service loop is left. • Use proper support methods when installing a cable in a dropped ceiling.

  40. FTP INSTALLATION • Cable Installation • Each horizontal run should be a continuous link to a single work area. • Bridging of horizontal runs is not acceptable. • Do not split pairs between multiple outlets. • All four pairs must be connected to a single jack or connector.

  41. FTP CABLE INSTALLATION QUESTIONS?

  42. FTP CABLE TERMINATION NETWORK CABLE SOLUTIONSMODULE 2-L

  43. FTP TERMINATION • Termination of FTP cable from UTP differs in that: • Shield continuity must be maintained throughout the system. • Shield must be grounded.

  44. FTP TERMINATION • Termination Procedures • Strip cable to expose conductors, drain wire and foil. • Cut foil even with outer jacket. • Slip cable over grounding tab. Be sure that the tab is on the inside of the foil shield. • Bend drain wire ground tabs against the cable. • Wrap the drain wire around the tabs and the cable. • Apply tie wrap to assure good contact of drain wire to grounding tab. • Punch pairs down. • Snap metal shield over connector.

  45. FTP CABLE TERMINATION QUESTIONS?

  46. LAN CABLING SYSTEMS OVERVIEW NETWORK CABLE SOLUTIONSMODULE 3-A

  47. LOCAL AREA NETWORK A Local Area Network or LAN is a system that interconnects data devices to share information at high speeds in a limited geographic area. Accomplished with a combination of hardware and software.

  48. LAN CABLING • LAN cabling provides a path to distribute data signals • The objective of the cabling systems is to be reliable and error free • Could be the most expensive component of a LAN. • May restrict technology. • Important element in high speed LAN’s

  49. NETWORK CABLING FACT • 70% of all LAN problems are directly related to the media. • 90% of all LAN problems are directly related to the media and physical hardware.

  50. CABLING FACTS Why you should assure only the best cabling system is installed in your facility.

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