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 MIL-HDBK-1012/3
Change 1, 30 November 1996
not recommended for operations above 10 MHZ because of their
susceptibility to wide variations in attenuation as a result of
variations in temperature. To support rapidly rising data rates over
a 10-year period, the use of CAT 3 cable should be restricted to
voice or alarm systems. CAT 5 cable may also be employed for voice
circuits where specified by the military department (MILDEP) or to
avoid excessive levels of cross talk. UTP is not specified as the
transmission media for data circuits which exceed a transmission rate
of 100 MHZ. However, UTP cables are being researched for use at data
rates in excess of 100 MHZ for applications such as the transmission
of asynchronous transfer mode (ATM).
Additionally, the National
Electrical Manufacturers' Association (NEMA) is developing a
specification, WC-66, for a high frequency low loss, extended
frequency 100 ohm screened or shielded cable for operations up to 300
MHZ.
1.3.2.2
Fiber Optic Cable. Fiber optic media must comply with
EIA/TIA 568, EIA TSB-72, Centralized Optical Fiber Cabling
Guidelines, and Article 770 of NFPA 70. Fiber optic media in
vertical pathways must conform to UL 1666, Flame Propagation Height
of Electrical and Optical Fiber Cables Installed Vertically in
Shafts. Fiber optic media in air handling plenums must pass NFPA
262, Fire and Smoke Characteristics of Wires and Cables. Multimode,
62.5/125 micron, tight buffered, tight tube, fiber distributed
digital interface (FDDI) grade fiber optic cable should be installed
in the vertical backbone to support data systems and may be
substituted for the CAT 5 horizontal data cable when required by user
terminal equipment. Installation and termination of fiber optic
cable is comparable to that of CAT 5 in cost and level of effort;
however, the cost of the electronics necessary for electro-optic
conversion results in a somewhat higher total cost for the fiber
optic installation. This cost is decreasing. When employed, the
fiber optic jack will be a duplex device housing two unidirectional
fiber optic terminations. The duplex 568SC connector specified in
EIA/TIA 568 is shown in Figure 6. Activities currently employing ST
connectors may continue to do so.
Single-mode fiber may be required for inter-building
backbone applications and may be specified by the major claimant for
vertical backbone support of high data rates.
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