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
