Spectral segmentation and multiple frequency-band tomographic backward propagation technique for high-resolution sonar imaging

This paper describes the multiple frequency-band tomographic backward propagation technique for sonar imaging. This technique models the received array time data as the complex superposition of plane waves of different wavelengths. The received plane waves are individually backward propagated to the image space to form single frequency holographic reconstructions. The individual holograms are coherently superimposed to form a final tomographic reconstruction of the image with superior resolution over the single-frequency holographic images. This paper outlines the backward propagation technique for sonar imaging, derives a quantitative description of performance under wide bandwidth conditions, and highlights the similarities of this technique with the popular phase-shift beamforming algorithm