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Vertical array receptions of the Heard Island transmissions

Technical Report ·
OSTI ID:6709936
 [1];  [2]; ;  [3];  [4];  [5]
  1. Massachusetts Inst. of Tech., Cambridge, MA (United States)
  2. Monterey Bay Aquarium Research Inst., Pacific Grove, CA (United States)
  3. Naval Postgraduate School, Monterey, CA (United States)
  4. Science Applications International Corp., Golden, CO (United States)
  5. Woods Hole Oceanographic Institution
+ Show Author Affiliations

The Heard Island Feasibility Test (HIFT) demonstrated that coded acoustic signals could be detected at ranges up to 18,000 km with currently available source technology. This paper describes one component of the HIFT where a large aperture vertical line array was deployed to record the signals transmitted from Heard Island. We have performed four analysis Of the VLA receptions, of the Heard Island signals. All four suggest the presence of higher order modes. The frequency- vertical wavenumber analysis and the modal beamforming indicate that mode 3 has the highest amplitude while the modal fitting suggests that made 5--6 are largest. It is difficult to resolve the differences since the SNR at the VLA, nearly 18,000 km with a transmission loss of around 145 dB, is quite low. Individual arrivals could not be distinguished because of the long integration time necessitated by the low SNR.

Research Organization:
Woods Hole Oceanographic Institution, MA (United States)
Sponsoring Organization:
DOE; USDOE, Washington, DC (United States)
DOE Contract Number:
FG02-91ER61100
OSTI ID:
6709936
Report Number(s):
DOE/ER/61100-1; ON: DE94013784
Country of Publication:
United States
Language:
English

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Related Subjects

440800 -- Miscellaneous Instrumentation-- (1990-)
47 OTHER INSTRUMENTATION
54 ENVIRONMENTAL SCIENCES
540110*
661300 -- Other Aspects of Physical Science-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACOUSTIC DETECTION
ACOUSTIC MEASUREMENTS
ACOUSTIC TESTING
BERMUDA
CHARGED PARTICLE DETECTION
CLIMATIC CHANGE
DETECTION
DEVELOPED COUNTRIES
EUROPE
FEASIBILITY STUDIES
GLOBAL ASPECTS
HAMILTONIANS
INDIAN OCEAN
ISLANDS
MATERIALS TESTING
MATHEMATICAL OPERATORS
NONDESTRUCTIVE TESTING
QUANTUM OPERATORS
RADIATION DETECTION
SEAS
SURFACE WATERS
TESTING
UNITED KINGDOM
WESTERN EUROPE