Sonar bearing estimation of extended targets
First Claim
1. A sonar system for determining the bearing of a signal source providing a segmented signal comprising:
- a sonar array providing a pair of offset-phase centered beams, said pair of beams being characterized as right and left phase displaced beams with respect to an axis through a phase center of said sonar array;
said right and left beams providing a right and a left phase displaced signal, respectively, from said signal source;
means providing a plurality of correlation products corresponding to the segments of said segmented signal of each of the right and left phase displaced sonar array output signals;
said correlation products each containing a pair of a real and an imaginary part; and
means determining a bearing with respect to said axis of a source of said output signals from an argument derived from at least some of said pairs of correlation products.
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Abstract
An improved bearing estimation sonar system provides high resolution imaging of extended multi-highlight targets at long ranges. The complex outputs of a pair of offset-phase centered beams are first processed by segmented replica correlators to achieve pulse compression, followed by cross-correlation to provide high fidelity bearing estimates for target imaging. The technique exploits space-time coherence properties of the target receive signal to extract high resolution target information. The processing employed in the system also includes data editing schemes resulting in enhanced discernability of submarine-like targets which is essential for target classification. Substantial processing gains are realizable by the system of this invention.
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Citations
11 Claims
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1. A sonar system for determining the bearing of a signal source providing a segmented signal comprising:
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a sonar array providing a pair of offset-phase centered beams, said pair of beams being characterized as right and left phase displaced beams with respect to an axis through a phase center of said sonar array; said right and left beams providing a right and a left phase displaced signal, respectively, from said signal source; means providing a plurality of correlation products corresponding to the segments of said segmented signal of each of the right and left phase displaced sonar array output signals; said correlation products each containing a pair of a real and an imaginary part; and means determining a bearing with respect to said axis of a source of said output signals from an argument derived from at least some of said pairs of correlation products. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A sonar system comprising:
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means providing a plurality of phase-center separated beams; means providing a transmitted waveform having a time-bandwidth product; means segmenting said transmitted waveform; segmented replica correlator means each connected to one of said means providing said beams for receiving signals by said beams; each said segmented replica correlator providing a plurality of outputs each corresponding to a segment; multiplier means having inputs connected to corresponding outputs of each of said segmented replica correlators; each said multiplier means providing a complex output signal having a real and imaginary part; first means summing said real parts of said multiplier means output signals to provide a first output signal; second means summing said imaginary parts of said multiplier means output signals to provide a second output signal; means obtaining an argument of the first and second output signals; and means converting said argument into a bearing angle of said beam providing means. - View Dependent Claims (8, 9, 10)
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11. A sonar system for determining the bearing of a signal source providing a segmented signal comprising:
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an array of transducers providing a beam axis along which said signals from said signal source has zero phase difference in an output of each of a first and second array of transducers; said first and second array providing offset-phase centered first and second beams which provide output signals with a relative phase difference for a signal source off said beam axis; means providing a plurality of correlation products of the segmented signal from the first and second phase displaced sonar array output signals; said correlation product containing a real and an imaginary part; means providing an argument for each of said real and imaginary parts; and means determining a bearing of said source of said output signals from the argument derived from at least some of said pairs of correlation products.
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Specification