A stable data-adaptive method for matched-field array processing in acoustic waveguides

Abstract

Capon’s maximum likelihood (ML) method has been used with some success in matched field processing for source range and depth estimation. One reason for the interest in the ML is that it is data adaptive; that is, it adapts to the actual noise field present rather than requiring an a priori estimate of the noise component for prewhitening. When modal noise is present the ML can become sensitive to any deviations from the unperturbed case (i.e., from the model) as would be introduced by phase errors or model parameter errors. Using a dimensionality-reduction procedure a more stable data adaptive method, the ‘‘reduced’’ ML (RML), is obtained. The RML is compared here with the ML on simulated data from a 21-sensor array in a Pekeris waveguide supporting eight normal modes. Under modal noise conditions the RML provides a significant improvement over ML when phase errors occur. Although the deviation from the model considered here is that caused by phase errors, the nature of the perturbation is not important since the sensitivity of ML is not to any special type of perturbation.

Fault-Tolerant Matched-Field Processing in the Presence of Element Failures

“…Several algorithms for determining the reduced-rank approximation have been introduced to enhance beamforming performance when there are environmental mismatches. 10,11,20 The signal power threshold method selects the eigenvectors associated with eigenvalues containing a large fraction of total power given by…”

Matched field source detection and localization in high noise environments: A novel reduced-rank signal processing approach

“…Byrne et. ale applied Capon's maximum likelihood method (MLM) to estimate the range and depth of an acoustic source [24]. The MLM offers the capability to adapt to the actual noise rather than requiring an a priori estimate for prewhitening.…”

“…Lastly, we recommend further investigation in the GLRT maxima analysis area. We derive the three dimensional reduced wave equation for the cylindrically symmetric case given by equation (8) of reference [24]. This derivation is the mathematical basis for the PIE Solver algorithm used in this investigation.…”

“…which is equation 3of reference [24]. Next we define an operator Q as: and after additional manipulations for range independent environments equation (A.21) can be written as:…”