Lesson 3/Learning Event 1
a. Interconnecting VF Circuits. Provisions are made for converting 2W
to 4W circuits, and vice versa.
Amplifiers raise signal levels where
necessary, and attenuators reduce their levels.
There is not provision
for equalizing since the primary function of the AN/MSQ-73 is connecting,
not terminating.
Instruments permit testing of most signal parameters
important to transmission over VF circuits.
b. Interconnecting
DC
Circuits.
Provisions
are
made
for
interconnecting telegraph circuits through the use of isolation relays.
Regenerative repeaters are not used, so the equipment in the van neither
discriminates nor accommodates differences in speed of transmission;
outgoing signal speed is identical with incoming signal speed. Strategic
communication systems use single-wire ground return for telegraph
communication, while tactical communication systems use metallic pairs.
However, the values of current may be different in the two systems. These
problems are overcome by using isolation relays.
The speed of
transmission through the van is limited by the speed capability of the
When the speed of transmission exceeds the capability of the
relays (as for data signals), circuits will have to be engineered so that
connections can be made without relays.
c. Wideband Circuits.
There is no provision in the AN/MSQ-73 to
connect wideband communication channels--channels which exceed the
bandwidth of a normal voice charnel.
There are no spiral-four cable
connectors nor coaxial cable connectors in the van.
The AN/MSQ-73 is
therefore limited to interconnecting voice loop sides of telephone carrier
terminals; it cannot connect the lines between terminals.
d. Compatibility Factors. Three principal characteristics enter into
the problems of connecting tactical and strategic communication systems
through the AN/MSQ-73.
These three characteristics include the tactical
communication facility, the strategic communication facility, and the
interface within the AN/MSQ-73.
Since the AN/MSQ-73 has no terminating
facilities, system terminals must be located in the vicinity of the
shelter.
Voice loops form these terminals interface on the AN/MSQ-73
patch boards, and DC or VF telegraph loops interface on appropriate DC or
VF patch boards.
(1) Levels. Each telephone carrier terminal uses specified levels. If
these levels are similar, the problem of interconnecting the tactical and
strategic communication terminals is simple to solve.
The major problem
remaining is to adjust the
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