Communications – electrical: acoustic wave systems and devices – Sonar counter-measures
Reexamination Certificate
2000-02-28
2001-07-03
Lobo, Ian J. (Department: 3662)
Communications, electrical: acoustic wave systems and devices
Sonar counter-measures
C367S118000, C367S129000
Reexamination Certificate
active
06256263
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates generally to acoustic signal detection and more particularly, to an acoustic sensing countermeasure device and a method of determining a threat direction.
(2) Description of the Prior Art
Countermeasures are commonly used to prevent a homing system from finding a submarine or other vessel. Countermeasures typically include acoustic devices deployed by the vessel to project either noise or an interference signal to mask or confuse a torpedo or other projectile or vehicle posing a threat to the vessel. Although existing countermeasures have been successful in countering threats and protecting vessels, the existing countermeasures do not have the capability of sensing and providing directional information of the threat being countered. Knowledge of the direction in which a threat projectile or vehicle is traveling can assist the submarine or vessel in evading the threat.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a countermeasure capable of sensing a threat direction.
Another object of the present invention is a countermeasure capable of providing directional information to a vessel.
Another object of the present invention is a method of determining threat direction information and transmitting the threat direction information.
The present invention features a threat direction sensing countermeasure device comprising a countermeasure housing having a generally cylindrical shape and an acoustic receive array mounted around the countermeasure housing. The acoustic receive array includes a plurality of acoustic sensors for sensing acoustic signals representing a threat. The acoustic sensors are grouped to form directional acoustic beams for indicating a threat direction relative to the countermeasure device. The acoustic sensors are preferably arranged as segmented, vertical staves around the countermeasure housing. The countermeasure housing preferably has a reduced outer diameter section in which the acoustic receive array is mounted.
In one embodiment, the countermeasure device further comprises a direction location device coupled to the countermeasure housing for locating a known reference direction. The known reference direction and the threat direction can be used to determine a bearing of the threat represented by the acoustic signals. In one example, the direction location device is a compass and a compass heading of North is the known reference direction.
The countermeasure device preferably comprises a bearing signal transmitter for transmitting a bearing signal representing the bearing of the threat. In one example, the bearing signal is a coded signal transmitted with countermeasure interference signals.
The present invention also features a method of determining a threat direction. The method comprises deploying one or more acoustic sensing devices having acoustic sensors grouped to form directional acoustic beams; locating a known reference direction; linking the reference direction to a reference directional acoustic beam; receiving threat acoustic signals on one or more of the acoustic sensors; determining a threat directional acoustic beam based upon the acoustic sensors receiving the threat acoustic signals; and transmitting bearing information including the reference directional acoustic beam and the threat directional acoustic beam. Where the acoustic sensing device is a countermeasure deployed from a vessel, the countermeasure transmits countermeasure signals and the bearing information is transmitted as a coded signal with the countermeasure signals.
According to one method, the reference direction is located using a compass coupled to the acoustic sensing device where the compass heading of North is linked to the reference directional acoustic beam.
According to another method, the step of locating the reference direction includes receiving reference acoustic signals on one or more acoustic sensors from a signal source having a known location; and determining the reference directional acoustic beam based upon the acoustic sensors receiving the reference acoustic signals. Where the acoustic sensing device is a countermeasure deployed from a vessel, the vessel can be the signal source having the known location.
According to a further method, first and second acoustic sensing devices are deployed and each of the first and second acoustic sensing devices determine the known reference direction with respect to each other. Each of the first and second acoustic sensing devices also receive the threat acoustic signals and determine the threat direction acoustic beam.
REFERENCES:
patent: 4215630 (1980-08-01), Hagelberg et al.
patent: 5339281 (1994-08-01), Narendra et al.
patent: 5457662 (1995-10-01), Forster
patent: 5615175 (1997-03-01), Carter et al.
Gauthier Robert W.
Lall Prithvi C.
Lobo Ian J.
McGowan Michael J.
The United States of America as represented by the Secretary of
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