ATAC/DLC.— The air transportable communi-
cation (ATAC) and down-link communication (DLC)
buoys are intended for use as a means of communi-
cation between an aircraft and a submarine. The
ATAC buoy is commendable from the aircraft and
provides up-link and down-link communications by a
preselected code.
The DLC buoy is not com-
mandable and provides a down-link communications
only by a preselected code.
SONOBUOY RECEIVERS
Learning Objective: Recognize the operating
principles and components of a typical
sonobuoy receiver.
The sonobuoy receiver set that will be discussed
in this chapter is the AN/ARR-75. This set is used on
the H-60 LAMPS helicopter.
The radio receiving set (RRS) receives,
demodulates, and amplifies sonobuoy transmissions
in the VHF bands, It provides channels A, B, C, and
D acoustic data to the data link for transmission to the
ship via the communications system control group.
Channels E, F, G, and H acoustic data is provided
direct to the data link for transmission to the ship.
The acoustic data is also routed to the spectrum
analyzer group for processing and display on board
the aircraft. Simultaneous reception and demodu-
lation of standard sonobuoy RF channels is possible.
Any one of the received channels can be selected for
aural monitoring.
The RRS consists of two radio
receiver groups.
The radio receiver groups each consist of four
VHF radio receivers and a power supply. Each of the
four receivers can operate on a separate channel,
independent of the others. The RF signals received
by the sonobuoy antennas are applied to each of the
four receiver modules, where tuned filters select the
signals for each module. The signals then pass
through a series of amplifiers, filters, and mixers to
produce the output audio signals. The output signals
are supplied to the spectrum analyzer group and the
data link system. The spectrum analyzer processes
the signals to allow monitoring by the aircrew.
ACOUSTIC SYSTEM
Learning Objective: Recognize components
and operating principles of a typical acoustic
system.
The AN/UYS-1 single advanced signal processor
system (SASP) processes sonobuoy acoustic audio
and displays the resulting data in a format suitable for
operator evaluation in the P3-C Update III aircraft.
OPERATING PRINCIPLES
The SASP processes sonobuoy audio in active
and passive processing modes to provide long range
search, detection, localization, and identification of
submarines. The sonobuoys presently in use include
the LOFAR, DIFAR, CASS, DICASS, and BT. The
RF signals from the sonobuoys are received by the
sonobuoy receivers and sent to the SASP. After
processing, signals are sent to the displays and the
recorders for operator use. The SASP also generates
command tones for controlling the CASS and
DICASS sonobuoys.
COMPONENTS
The major components include the TS-4008/
UYS-1 spectrum analyzer (SA), PP-7467/UYS-1
power supply, and the C-11104/UYS-1 control-
indicator (SASP power control).
TS-4008/UYS-1 Spectrum Analyzer
The TS-4008/UYS-1 spectrum analyzer is a
high-speed signal processor designed to extract
acoustic target information from both active and
passive sonobuoy data. The SA determines
frequency, amplitude, bearing, Doppler, range, and
other characteristics for acoustic targets.
PP-7467/UYS-1 Power Supply
The PP-7467/UYS-1 power supply converts 115
volts ac into 120 volts dc operating voltages. The
120-volt dc power is then converted to low-level dc
voltages for operation of individual circuits. A power
interrupt unit protects the data against transient power
interruptions that normally occur during airborne
operations.
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