stream. DAMA was designed to interface the Navy
UHF SATCOM baseband subsystem and the AN/WSC-
5 and AN/WSC-3 transceivers.
The TD-1271/U Multiplexer includes a modem
integral to the transceiver. The baseband equipment
input or output data rate with DAMA equipment can be
75, 300, 600, 1,200, 2,400, 4,800, or 16,000 bits per
second (bps). The DAMA transmission rate on the
satellite link (referred to as “burst rate”) can be 2,400,
9,600, 19,200, or 32,000 symbols per second.
Circuit Restoral/Coordination
When a termination is lost in either or both
directions, communications personnel must observe
special guidelines. During marginal or poor periods of
communications, the supervisors should assign a
dedicated operator to the circuit if possible.
When normal circuit restoration procedures are
unsuccessful and/or a complete loss of communications
exists, an IMMEDIATE precedence COMMSPOT
message should be transmitted (discussed earlier).
Every means available must be used to re-establish the
circuit, including messages, support from other ships or
NAVCOMTELSTAs, or coordination via DAMA if
available.
The guidelines established in NTP 4, CIBs, and
local SOPs are not intended to suppress individual
initiative in re-establishing lost communications.
Circuit restoral is dependent upon timely action, quick
decisions, and the ability of personnel to use any means
available to restore communications in the shortest
possible time.
SPECIAL CIRCUITS
During certain communications operations, you
may be required to activate and operate special circuits.
Some of the most common special circuits are discussed
next.
UHF AUTOCAT/SATCAT/MIDDLEMAN
RELAY CIRCUITS
Shipboard HERO conditions and emission control
(EMCON) restrictions often prohibit transmission of
RF below 30 MHz.
To provide an uninterrupted flow of essential
communications without violating HERO and EMCON
restrictions, AUTOCAT, SATCAT, and MIDDLEMAN
were developed. With these techniques, the range of
tactical UHF circuits (voice or teleprinter) can be
extended by relay of AM UHF transmissions via HF or
satellite. AUTOCAT accomplishes this using a ship;
whereas SATCAT uses an airborne platform for
automatically relaying UHF transmissions.
MIDDLEMAN requires an operator to copy the
messages with subsequent manual retransmission.
The three techniques just discussed use three
different types of circuit for reception and relay of UHF
transmissions. These circuits are as follows:
A voice circuit where some units send and
receive on one frequency, and other units send
and receive on any other frequency;
A voice circuit where all units transmit on one
frequency and receive on another frequency; and
A RATT circuit where all units transmit on one
frequency and receive on another frequency.
FLEET FLASH NET
The Fleet Flash Net (FFN) is composed of senior
operational staffs and other designated subscribers. The
purpose of the FFN is to distribute high-precedence or
highly sensitive traffic among subscribers. A receipt on
the net constitutes firm delivery, and the message need
not be retransmitted over other circuits to receipting
stations. The FFN is explained in more detail in Mission
Communications, NTP 11.
ANTENNA SYSTEMS
Operation of communication equipment over the
entire range of the RF spectrum requires many types of
atennnas. You will need to know the basic type of
antennas available to you operationally, their
characteristics, and their uses, Very often, you, the
operator, can mean the difference between efficient and
inefficient communications. You will have a choice of
many antennas and must select the one most suitable for
the task at hand. Your operational training will acquaint
you with the knowledge necessary to properly use the
antennas at your disposal, However, your operational
training WILL NOT acquaint you with the WHY of
antennas, in other words, basic antenna theory. The
following topics are intended to familiarize you with
basic antenna terminology, definitions, and
characteristics.
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