The Kauai Experiment: HighFrequency Channel Characterization

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The Kauai Experiment High-Frequency Channel
Characterization

• Michael Porter, Paul Hursky, Martin Siderius
• Ocean Sciences Division, Science Applications
  International
• William Hodgkiss
• Scripps Institution of Oceanography
• Dan Rouseff
• University of Washington, Applied Physics
  Laboratory
• Dan Kilfoyle
• Science Applications International, Woods Hole
• Larry Mayer, Christian de Moustier, Barbara Kraft
• University of New Hampshire
• Mohsen Badiey
• University of Delaware
• Keyko McDonald

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Experiment site
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Waypoints for equipment
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Experiment Objectives

• Characterize time-angle variation of HF (8-50
  kHz) ocean acoustic propagation (role of bottom,
  surface, bubble clouds, ocean thermal structure)
  as a function of range, frequency, and sea state
• Relate these properties of the channel to the
  performance of a variety of acoustic
  communications schemes

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Experiment Site
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Thermistor strings waverider buoy
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UDel Array
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MPL arrays
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UW array
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Telesonar testbeds
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Testbed Applications
Subsurface float

• Telesonar testbed applications
• SignalEx experiments
• acoustic model evaluation and verification
• directional transducer testing
• algorithm development and evaluation
• network protocol (design and testing)
• probe development
• platform for third party signal testing

4-channel (1.522 kHz) or 2-channel (1.550 kHz)
receiver array
816 kHz transmitter
2550 kHz transmitter
Modem (for remote control and mission status)
Record and transmit electronics
Burn-wire release
Anchor
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Added Capabilities

• Capabilities Added FY 02
• Remote control of testbeds
• High-accuracy clock added to each testbed
• One two-channel 1.550 kHz testbed receive array
• Two four-channel 1.522 kHz testbed receive
  arrays
• Projected Capabilities for FY 03
• Two new transmit bands 14-21, 2550 kHz
• Over-the-side four-channel 2550 kHz transmit
  array
• 32-bit floating point DSP added for real-time
  decoding

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Telesonar testbed deployment
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MPL Array (auton)
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UDel array
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SAIC/WHOI Source Deployment
R/V Revelle
Note Both arrays are not deployed simultaneously

Reference hydrophone
Tilt Meter/Compass/Pressure Sensor /Thermistor
String Unit
100 m
Array midpoint at 50 m 2 meter element spacing
HF source array frame Populated with 4 ITC-1032
sources 70 meter depth
6 MF AT-12ET sources
The sub-surface float deployment has successfully
been used by WHOI to provide substantial surface
wave isolation of vertical line arrays.
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APL Role in HFX
Send sequences designed both to test
communication algorithms and estimate the
channel impulse response. Deploy eight-element
vertical array at range 5 km, water depth 80
m. In each half-hour block, send five 10 second
long sequences. Record for 18 seconds bracketing
each sequence. Store data at array and download
samples via RF link to ship. Can operate 24/7
for two weeks with one battery pack change.
Goal Gather high quality data set with
detailed associated oceanographic
measurements.
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HFX Array Deployment Test February 11, 2003.
floats
array
Array is deployed top first with floats above
array.
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acoustic release
rail road wheel (anchor)
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anchor
Anchor ready for release. Anchor falls pulling
array into vertical.
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Attaching RF antenna and battery pack to array.
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battery pack
Array recovery. Battery pack visible near Zodiac.
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Waypoints