operational checks of equipment and antennas, and
consumable supply levels.
The Basic Operational Communications Doctrine
(U), NWP 4 (NWP 6-01), provides suggested
minimum check-off sheets, including a
predeployment check-off sheet and a preunderway
check-off sheet. The first sheet provides a timetable of
required checks and objectives. The second sheet is
tailored to individual ships and unique requirements.
LOW-FREQUENCY SYSTEMS
The low-frequency (LF) band (30-300 kHz) is used
for long-range direction finding, medium- and long-
range communications, aeronautical radio navigation,
and submarine communications.
A low-frequency transmitter, such as the AN/FRT-
72, is used to transmit a high-powered signal overlong
distances. Low-frequency transmitters are normally
used only at shore stations or for special applications.
The low-frequency receive system is designed to
receive low-frequency broadcast signals and to
reproduce the transmitted intelligence. A typical low-
frequency receive system is shown in figure 1-1. Refer
to the equipments in the figure as you study the next
section.
1.
2.
3.
4.
Antennas— The low-frequency signal is
received by the antennas, which are connected
to the receiver antenna patch panels and
multicouplers (AN/SRA-34, AN/SRA-57, or
AN/SRA-58). Multicouplers and patch panels
allow the operator to select different antennas
and connect them to different receivers. This
way, an operator can select the correct
combination suited for a particular system.
LF Receiver— The output of the receiver
(audio) is fed to the receiver transfer
switchboard.
Switchboard— The switchboard can connect
the receiver output to numerous pieces of
equipment. In figure 1-1, the receiver output is
connected to the AN/UCC-1 Teleprinter
Terminal (discussed later).
AN/UCC-1— The AN/UCC-1, as a converter
comparator, converts the received audio signal
Figure 1-1.—Low-frequency receive system.
1-2
