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Method for Real Time Matched Field Processing

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Patent application, Filed 30 Jan 2007

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This patent application discloses a method for computing real-time matched field responses. The method utilizes a matched-field processing algorithm and requires two data inputs. The first data input is measured acoustic data from a sonar set of hydrophones. The second data input is a predicted data set, or replica data set, against which the measured data are compared. Multiple replicas are compared to the measured data and the closest match is retained. The closest match of the replica is presumed to characterize the data in some important way e.g., a source location. More specifically, the output of a sensor of the towed array is translated to the frequency domain by applying a discrete Fourier transform DFT or a Fast Fourier transform FFT to a set of contiguous time samples. A replica vector is the frequency domain N x 1 vector representing the predicted or expected values at each sensor of the sensor array for a specific frequency. The corresponding output of the method is an ambiguity surface. The ambiguity surface is a set of numbers ranging between zero and one with each number corresponding to a specific location in the ocean. The highest values on the ambiguity surface indicate the most likely position of an acoustic source. The matched-field response is generalized by averaging the response over multiple frequencies. A response for an array may be computed by forming beams and then combining them by multiplying each by an eigenray factor before summing. The computation of the response may be further defined by Voxel interpolation.

Subject Categories:

  • Numerical Mathematics
  • Acoustic Detection and Detectors
  • Target Direction, Range and Position Finding
  • Radiofrequency Wave Propagation

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