Multiresolution Signal Cross-Correlation

Signal Correlation is a digital signal processing technique which has a wide variety of applications, ranging from geophysical exploration to acoustic signal enhancements, or beamforming. This dissertation will consider this technique in an underwater acoustics perspective, but the algorithms illustrated here can be readily applied to other areas. Although beamforming techniques have been studied for the past fifty years, modern beamforming systems still have difficulty in operating in noisy environments, especially in shallow water. Multiresolution Signal Decomposition is a technique for signal analysis and processing which emerged from the consolidation of similar ideas such as the Gabor Transform, the Wavelet Transform and Subband Filters. This dissertation will focus on the potential application of these techniques in underwater acoustic beamforming. The main objective of this research is to show that there is a significant improvement in the signal to noise ratio when the original signal is projected onto orthogonal spaces of adjacent bandwidths. This fact is proved experimentally in a simulation section, where the cross-correlation algorithm is applied separately to each projected sequence.