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Research Highlights
High Frequency
Submarine Sonar
The high frequency (HF) sonar systems
employed on US Navy attack class submarines were designed
in ATL. These sonar systems represent a significant capability
for the USN submarine force. The AN/BQS-15(A) is a standalone
system on the first flight SSN 688 class submarines. This
sonar was derived, in part, from the DS/OAS systems used
on special purpose submarines such as the USS Dolphin and
NR-1. Key elements of this sonar implementation include
a wide sector acoustic aperture, modular outboard pressure
tolerant electronic component configuration, outboard pressure
compensated oil filled cables, and single console inboard
processing and display. In addition, this sonar represents
the first fleet-wide use of color displays for detection
sonar systems.
The AN/BQS-15(A) sonar architecture supports wideband
coherent operation for high resolution; advanced, automated,
computer aided detection to assist the operator in target
classification; and first order monopulse processing for
precision height determination. A default system configuration
menu allows the operator to select the optimum system parameters
based on sonar position and environmental conditions. This
system has demonstrated exemplary active performance with
regard to the detection of targets both in the water column
and on the ocean bottom. Furthermore, the sonar provides
wide area single ping remote profiling of the ocean bottom
or an ice surface and allows discrimination for collision
avoidance.
The AN/BQQ-10 combat system employs a high frequency sonar
component that is an advanced version of the AN/BQS-15(A).
This sonar was developed under the ARCI/APB (Acoustic Rapid
COTS Insertion/Advanced Processing Build) build-test-build
process for implementation on the SSN 688I, SSN 21, and
Virginia class submarines. Key improvements of this sonar
implementation include a larger acoustic aperture with
precision matched acoustic channels, an expanded outboard
pressure tolerant electronic component configuration, and
the ability to pass element level data inboard.
The AN/BQQ-10 sonar
architecture allows expanded wideband coherent operation
for achieving improved high resolution and a wideband
computer aided detection implementation. The signal processing
provides an expanded second order monopulse implementation
in which both precision height finding and adaptive null
steering are supported. The system’s
detection performance is enhanced through the use of null
steered beams to reject reverberation.
High Frequency Ground Wave Antenna
The high frequency ground wave mode of communication is
an ideal mode for communicating over water for extended
line-of-sight distances. In the past, the primary barrier
to utilization of this mode has been the size of the antenna.
ARL:UT has developed a new type of small antenna called
the folded conical helix or FLEX antenna. FLEX antennas
may be packaged as either monopoles or dipoles allowing
the designer to evaluate trade-offs between the size and
the bandwidth of the antenna. Good efficiencies may be
maintained for antenna sizes as small as 0.02 wavelengths.
The efficiencies at these sizes are in the range of 50
to 80 percent, and all the antennas are self-resonant as
well as self-matched, with no external tuning or matching
elements required. These designs represent a significant
advancement over the state-of-the-art small monopole and
dipole antennas currently available, commercially or otherwise.
ATL Director, E-mail: atl_director@arlut.utexas.edu
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