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الموضوع: Cable categories

  1. #1
    Junior Engineer
    تاريخ التسجيل
    Sep 2006
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    makkah
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    Cable categories

    السلام عليكم ورحمة الله وبركاته

    Cable categories
    The "quality" of the cabling systems to carry high frequency signals is expressed with the folloging marking (those are in use in USA):
    • Cat 1: Cabling that meets the minimum requirements for analog voice or Plain Old Telephone Service (POTS). Also known with name Grade 1. Commonly called inside wire by the Telco community. (Informal designation)
    • Cat 2: This is a 100 ohm UTP system capable of operating 1 Mbps Token Ring and similar networks. This is also known as IBM Type 3 cabling system. Also known with name Grade 2. (Informal designation)
    • Cat 3: This cable type is characterized to 16 MHz and supports applications up to 10 Mbps. Applications may range from voice to 10BASE-T. This is a low performance cable rating which is dissapearing. This is nowadays the minimal requirement for good quality structured telephone cabling system. This is also known as ISO/IEC 11801 Class C cabling. This was the standard for UTP performance as late as 1988. The FCC recently changed the requirement for telephone inside wiring to minimum of Cat 3 due to crosstalk problems with nontwisted quad-four. CAT 3 is no longer recognized by TIA.
    • Cat 4: This cable type is characterized to 20 MHz and supports applications up to 16 Mbps. Applications may range from voice to 10BASE-T and 16 Mbps Token Ring. This cable type is not much used nowadays.
    • Cat 5: The traditional rating of cables for high speed data installation. Rated frequency is 100 MHz. This cable works well from voice to 100BASE-T Ethetnet and 155Mbps ATM. This cable type is also known as ISO/IEC 11801 Class D cabling. Today Cat 5 copper communications wiring is the recognized minimum for broadband services. The standard for thie wiring are ISO/IEC-11801 and TIA/EIA-568-A-5. CAT5 performance is only possible when cable, connector modules, patch cords, and all electronics carry the same CAT5 rating.
    • Cat 5e: New rating developed in USA. Rated frequency is 100 MHz. Cat 5E is becoming the new standard for premises wiring, because it is recommended as the minimum for all future installations by TIA/EIA, IEEE and many equipment manufacturers. Enhanced Category 5, was ratified in 1999.
    • Cat 6: A new rating just developed in US, ISO/IEC and CENELEC. Rated frequency is 200 MHz with some requirements specified for 250 MHz. Category 6 is being specified concurrently by both ISO in the 11801-2001 ******** and the TIA in its Category 6 addendum to TIA 568B (ANSI/TIA/EIA-568-B.2-1 ratified by the TIA/EIA in June 2002). This presents the best performance possible with the current T568A and T568B wiring configurations on an 8 position 8 conductor modular connector (RJ-45). In Europe this is known as ISO/IEC 11801 Class E cabing.
    • Cat 7: A rating for individual pair screened cables derived from the german DIN 44312-2 standard requirements. Rated frequency is 600 MHz. The work is on progress. This is also known as ISO/IEC 11801 Class E. This cable is fully shielded and uses non-standard RJ-45 interface (Alcatel hybrid RJ-45 connector).This cabling is primarily for European market place. Other alternative connector style is IBM Mini-C connector. In Europe this is known as Class F cabling.
    Generally the specification for different groups is determined by Attenuation/Cross Talk Ratio, the gap between attenuation and NEXT. Practically a minimum gap of 10 dB is required for a data signal to be readable. CAT-3 UTP cable rated at 16 MHz with 10 dB of headroom at 16 MHz. CAT-4 UTP cable rated at 20 MHz with 10 dB of headroom at 20 MHz. CAT-5 UTP cable rated at 100 MHz with 10 dB of headroom at 100 MHz.
    For installation to meet specific Category requirements all components must meet or exceed the designated Category. Using a Cat 3 receptacle (or patch cord) on Cat 6 reduces performance to Cat 3.
    Some naming for differetn cable types:
    • UTP = Unshielded Twisted (Balanced) 4-Pair Cable, 100 Ohms
    • STP = Overall foil/braid Shielded 2-pair Cable w/ Individually shielded, 150 Ohm
    • FTP = Overall foil shielded 4-pair Cable, 100 Ohm
    • ScTP = Overall foil/braid Shielded Cable, 100 or 120 Ohm
    Recommendations: Installing cable with less performance (including Category 5 and 3) than Category 5e cable risks costly re-wiring in the near future. Cat 5 is now considered obsolete except for maybe household use. Cat 5E or Cat 6 is the standard now. Telephone, data, computer network and video cabling should be "home runs" from each phone, workstation, TV, etc. to a central location typically near the incoming service of the telephone company and cable provider. Two Category 5e home run cables (each with 4 pairs) are recommended for every wall opening. One UTP cable is for computer network and the other UTP cable is for telephone, modem and fax.
    Generally it is a good idea to install an UTP cable system, unless you have a very good reason why you shoudl use STP cable system. STP cabling systems are more expensive and harder to install and maintain than UTP cabling systems, but are not necessarily any better in normal home / office environment.
    When installing cable, remeber that there are different cable types. In-wall wiring is designed to be done with solid core cable (usually CMR cable). This is the rightr cable type to use. Stranded wire patch cables are often specified for cable segments running from a wall jack to a PC and for patch panels. They are more flexible than solid core wire. If you hard used the solid core cable for this, the constant flexing of patch cables may wear-out solid core cable. Another reason is that solid core cable does not terminate reliably to a normal RJ-45 connector used in patch cables (solid core terminates very niceky only to RJ-45 wall plugs and patch panel connectors). Stranded cable does have also it's weaknesses. Stranded cable is susceptible to degradation from moisture infiltration, may use an alternate color code, and should not be used for long cables because of usually poorer specifications than same category solid core cable designed for in-wall wiring. TIA/EIA 568A specification specify a one network link to have up to 90 meters of in-wall wiring (thicker solid core cable) and in addition to this up to 10 meters of patch cable (thinner stranded wire).

  2. #2
    Junior Engineer
    تاريخ التسجيل
    Mar 2007
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    palestine
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    رد: Cable categories

    السلام عليكم ورحمة الله وبركاتهشكراً لك اخي الكريم

  3. #3
    دكتور مهندس الصورة الرمزية د/ عماد محمد
    تاريخ التسجيل
    Nov 2006
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    السعودية
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    رد: Cable categories

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    د.عماد

  4. #4
    عضو فى رابطة مهندسى الكهرباء العرب الصورة الرمزية احمد حماد
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    Aug 2006
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    Benha-Egypt
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    رد: Cable categories

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    السلام عليكم ورحمة الله وبركاته
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  5. #5
    عضو فى رابطة مهندسى الكهرباء العرب الصورة الرمزية وائل أحمد أحمد
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    Jun 2007
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    رد: Cable categories

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    شكراً لك اخي الكريم

  6. #6
    V.I.P Member الصورة الرمزية Abdul chanbour
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    Abu Dhabi
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    رد: Cable categories

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