SYSTEMS AND METHODS FOR DETECTION AND ANALYSIS OF AMPLITUDE MODULATION OF UNDERWATER SOUND
First Claim
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1. A method of processing sound, comprising:
- receiving the sound with one or more sound sensors;
converting the received sound to first and second electrical signals;
correlating the first and second electrical signals to provide a correlation signal;
identifying a peak in the correlation signal;
identifying a time delay associated with the peak in the correlation signal;
applying the time delay to the first electrical signal to provide a first time-delayed electrical signal;
multiplying portions of the second electrical signal by respective portions of the first time-delayed electrical signal to provide respective pluralities of product values;
calculating respective sums of each one of the pluralities of product values to provide a plurality of summed-product values; and
converting the plurality of summed-product values to a frequency domain signal.
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Abstract
Systems and methods for detection and analysis of amplitude modulation of underwater sound employ a product of a time delayed first electrical signal with a second electrical signal to generate a summed-product signal. The time delayed first electrical signal and the second electrical signal have an amplitude modulation indicative of characteristics of a vessel propeller. The summed-product signal is analyzed to detect a vessel and to determine the characteristics of the vessel propeller. In some arrangements a plurality of summed-product signals are analyzed to also determine a depth of the detected vessel.
23 Citations
24 Claims
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1. A method of processing sound, comprising:
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receiving the sound with one or more sound sensors; converting the received sound to first and second electrical signals; correlating the first and second electrical signals to provide a correlation signal; identifying a peak in the correlation signal; identifying a time delay associated with the peak in the correlation signal; applying the time delay to the first electrical signal to provide a first time-delayed electrical signal; multiplying portions of the second electrical signal by respective portions of the first time-delayed electrical signal to provide respective pluralities of product values; calculating respective sums of each one of the pluralities of product values to provide a plurality of summed-product values; and converting the plurality of summed-product values to a frequency domain signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for processing sound, comprising:
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one or more sound sensors adapted to receive the sound signal; a converter coupled to the one or more sound sensors and adapted to convert the received sound to first and second electrical signals; a correlator adapted to correlate the first and second electrical signals to provide a correlation signal; a correlation peak detector adapted to identify a first peak and a first time delay associated with the first peak in the correlation signal; at least one time delay module adapted to apply the first time delay to the first electrical signal to provide a first time-delayed electrical signal; at least one multiplication/summing module adapted to multiply portions of the second electrical signal by respective portions of the first time-delayed electrical signal to provide respective pluralities of product values and adapted to calculate respective sums of each one of the pluralities of product values to provide a plurality of summed-product values; and at least one spectrum analyzer adapted to convert the plurality of summed-product values to a frequency domain signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification