Communications – electrical: acoustic wave systems and devices – Distance or direction finding – With towing
Reexamination Certificate
2001-05-11
2003-02-25
Pihulic, Daniel T. (Department: 3662)
Communications, electrical: acoustic wave systems and devices
Distance or direction finding
With towing
C367S118000, C367S124000
Reexamination Certificate
active
06525994
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention generally relates to sonar systems and more specifically to sonar systems particularly adapted for identifying the location of an underwater object.
(2) Description of the Prior Art
Conventional passive sonar systems detect acoustic signals emanating from an underwater object; that is, any device that moves through the water while emitting acoustic signals that sonar can detect. Torpedoes and submarines are examples of such underwater objects.
As modern, very quiet submarine platforms become operational in large numbers, new methods of detecting very low level signals from these quiet submarine platforms are desired, especially in the presence of high noise levels from surface shipping, wind, biologics, and other sources of ambient noise. Currently, post processing narrowband beamformed data from sonar arrays is performed by spectrally flattening, or whitening a selected beam's data by use of a noise spectral equalization (nse) algorithm and displaying the resulting signal-to-noise (SNR) as several shades of gray on a LOFARGRAM display. There are several disadvantages to this type of algorithm and display. First, the beamformed data and threshold are discarded and eliminated from the detection process. Second, the beamformed data from one beam are not compared to adjacent spatial beams to compare relative levels, and therefore, beamformed data are thresholded independently for all beams. Third, beamformed data are assumed to contain energy of interest only in very narrow frequency bands (<0.1 Hz) or in very broadbands (>25 Hz), and energy of intermediate bandwidths (BWs) are not addressed by current post processing algorithms. Modern submarine platforms of interest radiate energy in all bandwidths and an algorithm is desired to be developed for the detection of energy in all bandwidths.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a system that detects and measures energy in all bandwidth emanating from an underwater object.
Another object of the present invention to improve detection of signals present in noisy backgrounds.
In addition, it is an object of the present invention to provide a system having improved detection of signals of interest emanating from submerged objects.
Accordingly, the current invention provides a method and apparatus for detecting, processing and tracking sonar signals to provide bearing, range and depth information that locates an object in three-dimensions underwater space. A Twenty Six Nearest Neighbor Peak Picker (TSNNPP) is disclosed that improves the detection of signals in noisy background by differentiating bandwidth (BW) characteristics of signals from BW characteristics of noise.
REFERENCES:
patent: 5481505 (1996-01-01), Donald et al.
Dr. James H. Wilson, Inverse Beamforming, 1997, www.neptunesci.com/ibf.htm.
Donald James B.
Wilson James H.
Kasischke James M.
Nasser Jean-Paul
Oglo Michael F.
Pihulic Daniel T.
The United States of America as represented by the Secretary of
LandOfFree
Tracking system and method of operation thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tracking system and method of operation thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tracking system and method of operation thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3180783