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CROSS-CORRELATION LOSS CAUSED BY BOTTOM REFLECTION,
NAVY UNDERWATER SOUND LAB NEW LONDON CONN
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The cross-correlation between an incident direct and a bottom-reflected pulse is analyzed, and the physical models of the reflection process are briefly reviewed. A three-layer model is assumed for the analysis performed in this report. The bottom is considered to act as a linear filter, and the transfer function, which includes the general case of attenuation and phase shift, is given for the filter. A random function with a flat spectrum and finite bandwidth is transmitted, and the cross-correlation between the direct and the bottom-reflected versions of this random function is obtained. For the special case of no attenuation, there is negligible change in the correlation peak when Q or 1.5, where Q is the center frequency divided by the bandwidth. The cross-correlation peak is evaluated as a function of the bandwidth in Hz and the attenuation in nepersHz. Author
APPROVED FOR PUBLIC RELEASE