Quantcast  Wire-line modems

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MIL-HDBK-232A
c.
What special treatment is required for that signal.
d.
What effects can degrade that signal.
e.
What effects can that signal cause.
5.4.1
Treatment of signal types.
5.4.1.1  Analog signals.  Analog signals in a facility can be grouped in six
categories.  (Including quasi-analog signaling as defined in FED-STD-1037.)
a.
Quasi-analog signals supporting wire-line modems.
b.
Analog signals originating in radios.
c.
Analog signals in administrative telephone systems.
d.
Quasi-analog signals in secure voice systems.
e.
Quasi-analog signals supporting video systems.
f.
Quasi-analog signals associated with broadband local area networks
(LANs).
5.4.1.1.1  Wire-line modems.  Quasi-analog signals from wire-line modems are
the most common such signals encountered in a facility.  The distribution of
these signals, which are typically BLACK, is the least complex.  Typical
routing is from the modem to an analog frame and patch bay, to a DF, to the
facility entrance plate.  Cabling between units typically uses twisted pairs
and may have each pair shielded.  All cables should be filtered at the
facility entrance plate.  All cabling should be contained in metallic wire
ways, ducts, or conduits.  Where analog signals are RED, separate
distribution and patching facilities are required in addition to physical
security measures.
5.4.1.1.2  Radio.  Radio transmitters should not be located within the LEA.
However, in specialized facilities, the exclusion of radios may not be
operationally possible.  Such radios may be used for voice or data
transmission.  Treatment of signal distribution for radios begins with proper
separation of the radio from all other equipment.  In applications involving
voice communications in Command and Control facilities, it is assumed that
microphones or radio telephone handsets will be located in an operations area
which may be an REA.  In such cases. the cables must be distributed from the
radio rack to the REA in dedicated conduit, with separation similar to that
for administrative telephones.  The cables should also he filtered at the
REA.  Microphones and handsets should be equipped with push-to-talk,
push-to-listen switches.  In applications involving data communications, it
is assumed that the circuit will be secure, and the input to the radio is
digital and probably encrypted.  In such cases, the input distribution is the
same as any digital circuit.  The output of the radio, regardless of its use
in an LEA, is treated to prevent RFI/EMI.  At the entrance plate, the cable
should be filtered with a bandpass filter appropriate for the frequency of
the radio.
5.4.1.1.3  Administrative telephones.  Administrative telephone signal
distribution in an LEA is separate from all other distribution.  All cables
enter at the facility entrance plate where filtering and EMP treatment is
applied. This applies to telephone for voice communications only not





 


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