Correlation match filter for passive signal detection
First Claim
1. A passive target detector employing a correlation match filter comprising:
- beam forming means for forming two passive phase offset beams and dynamically sweeping said beats across a target to generate first and second phase offset received signals;
complex correlation means connected to said beam forming means for generating a complex cross-correlation coefficient of said first and second phase offset signals, said coefficient having real and imaginary parts;
replica function generating means for generating a replica signal in the form of complementary functions of a relative angle between a sensor line-of-sight and a source of signal to be detected;
four quadrant multiplier means for multiplying said real and imaginary parts of said coefficient by said complementary functions to generate a plurality of partial products;
summing and integrating means for accumulating over time the partial products from said four quadrant multiplier means to provide real and imaginary filter outputs; and
output means connected to said summing and integrating means for generating a detection output if a target has been detected.
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Abstract
A passive detection technique is based on correlation characteristics of split beam inputs with given relative rates between a detection sensor platform and a target source. The correlation coefficient (10, 12) between two phase offset beams is first computed and, at the same time, the relative angular position between the sensor line-of-sight and the target source are estimated (14) to establish the pattern matching function. The correlation operations are carried out for both real and imaginary channels with a four quadrant multiplier (20, 22, 24, and 26). The outputs of the multiplier are summed (28, 30) to obtain real and imaginary channel outputs which are smoothed over a period of time in integrators (32, 34) to eliminate undesirable correlation patterns. The outputs of the integrators are independently thresholded (36, 40) and square summed (38, 42 and 44) and then threshold (46) to provide an indication of target detection.
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Citations
6 Claims
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1. A passive target detector employing a correlation match filter comprising:
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beam forming means for forming two passive phase offset beams and dynamically sweeping said beats across a target to generate first and second phase offset received signals; complex correlation means connected to said beam forming means for generating a complex cross-correlation coefficient of said first and second phase offset signals, said coefficient having real and imaginary parts; replica function generating means for generating a replica signal in the form of complementary functions of a relative angle between a sensor line-of-sight and a source of signal to be detected; four quadrant multiplier means for multiplying said real and imaginary parts of said coefficient by said complementary functions to generate a plurality of partial products; summing and integrating means for accumulating over time the partial products from said four quadrant multiplier means to provide real and imaginary filter outputs; and output means connected to said summing and integrating means for generating a detection output if a target has been detected. - View Dependent Claims (2, 3)
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4. A method for detecting an acoustic source in a correlated or uncorrelated noise background comprising the steps of:
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forming two passive phase offset beams which are dynamically swept across a target to generate first and second received signals; continuously cross-correlating said first and second signals to produce a complex correlation coefficient having real and imaginary parts; generating complementary functions of a relative angle between a sensor line-of-sight and a source of signal to be detected; multiplying real and imaginary parts of said complex correlation coefficient by said complementary functions to produce real and imaginary product signals; and accumulating over time said real and imaginary product signals to produce first and second accumulated signals to determine if a target has been detected. - View Dependent Claims (5, 6)
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Specification