ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

5aUW12. Estimation of bottom scattering characteristics from acoustic reverberation special research program bistatic data.

Joseph E. Bondaryk

Ira Dyer

Eugene Dorfman

Dept. of Ocean Eng., Rm. 5-435, MIT, 77 Massachusetts Ave., Cambridge, MA 02139

For many years, sonar practitioners have used Lambert's law on a flat bottom to describe clutter due to bottom reverberation. This examination of a subset of the bistatic data from the B[sup '] site of the ARSRP natural laboratory examines the validity of this approximation. Eight pings transmitted by the Cory Chouest and received by the Alliance were chosen to cover the bistatic angular range of -90 to +90 deg with respect to B'. Transmission loss and area corrections to a flat bottom of representative depth were calculated using the ARTIST ray-tracing program. These corrections were applied to the data to compute scattering strength in each beam-time bin. This scattering strength was averaged over areas with similar grazing angle to transmitter, grazing angle to receiver and bistatic angle. Again, these are angles to a flat bottom scenario. The scattering strength plotted versus these three angles shows that neither Lambert's law nor the generalized version by Nayar et al. describe bistatic scattering. [Research supported by ONR.]