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  CommServ > Infrastructure > Standards > History > TSB-36 Additional Specifications

The EIA/TIA-568 standard applies to cables designated as Category 3 for characteristics of cables intended for speeds up to 16 MHz. The TSB-36 bulletin provides "requirements on the transmission characteristics of high performance unshielded pair cables (UTP)."

The categories of UTP cables are defined below:

  • Category 1 and 2: These voice and low-speed data cables are not covered by this bulletin, nor are they recognized by the EIA/TIA 568 standard.
  • Category 3: This designation applies to cables currently specified in the EIA/TIA 568 standard. The characteristics of these cables are specified up to 16 MHz.
  • Category 4: The characteristics of these cables are specified up to 20 MHz. The IEEE 802.5 16 Mbps UTP standard currently in development will address these characteristics.
  • Category 5: The characteristics of these cables are specified up to 100 MHz. The IEEE 802.5 16 Mbps UTP standard and ANSI X3T9.5 100 Mbps TPDDI study group will address these characteristics.

"The two new categories of unshielded twisted pair cables, currently on the market, are referred to as Enhanced Unshielded Twisted Pair (EUTP) cables. These cables provide improved Signal-to-Crosstalk noise margins that are required to unsure reliable operation for certain LAN systems operating at 16 Mbps and higher over cable distances up to 100 meters between the hub and station."

Transmission Characteristics

Mutual Capacitance

The mutual capacitance of any pair at 1 kHz and measured at or corrected at a temperature of 20C, shall not exceed 17 nF per 305 m (1000 ft) for category 4 and category 5 cables.

Characteristic Impedance

Both category 4 and category 5 cables shall have a characteristics impedance of 100 Ohms +/- 15% in the frequency range from 1 MHz up to the highest referenced frequency.

NOTE: The method of measuring "characteristic impedance" is currently under study by the industry. As a result of structural non-uniformities, the measured input impedance for an electrically long length of cable will fluctuate as a function of frequency. This fluctuation is related to the Structural Return Loss (SRL) for a cable that is terminated in its own characteristic. Generally, the Enhanced Unshielded Twisted Pair (EUTP) cables in categories 4 and 5 provide improved SRL performance.

Attenuation

The maximum attenuation of any pair shall be less than the values given in the following table in the frequency range for 0.772 MHz to the highest referenced frequency.

Maximum Attenuation dB per 1000 ft @ 20C

FrequencyMHz   Category 3   Category 4   Category 5

  0.064             2.8           2.3            2.2
  0.256             4.0           3.4            3.2
  0.512             5.6           4.6            4.5
  0.772             6.8           5.7            5.5
  1.0               7.8           6.5            6.3
  4.0               17           13             13
  8.0               26           19             18
 10.0               30           22             20
 16.0               40           27             25
 20.0                -           31             28
 25.0                -            -             32
 31.25               -            -             36
 62.5                -            -             52
100                  -            -             67

Near-End Crosstalk (NEXT)

The NEXT value at 0.772 MHz shall be 43 dB for category 3 cable, 58 dB for category 4 cable and 64 dB for category 5 cable.

The following table gives values of worst pair NEXT Loss at specific frequencies in the band of interest.

FrequencyMHz   Category 3   Category 4   Category 5

  0.150             54             68           74
  0.772             43             58           64
  1.0               41             56           62
  4.0               32             47           53
  8.0               28             42           48
 10.0               26             41           47
 16.0               23             38           44
 20.0                -             36           42
 25.0                -              -           41
 31.25               -              -           40
 62.5                -              -           35
100                  -              -           32

NOTES: The NEXT Loss of patch cable shall be equivalent to the NEXT loss of equal length of horizontal cable over the range of frequencies specified for any given cable category.

The NEXT Loss for connectors should be better than the NEXT values for any given cable category specified above.

DCC

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Last modified: 10/19/2007