## 4pUW13. A numerical study of time-domain backscattering from one-dimensional, rigid, random surfaces.

### Session: Thursday Afternoon, December 5

### Time: 4:27

**Author: Vincent Lupien**

**Location: Dept. of Ocean Eng., MIT, Cambridge, MA 02139**

**Abstract:**

In certain high-resolution target detection systems, impulsive scatter from
ocean boundaries gives rise to sonar clutter. In this work, the main objective
was to identify the stochastic characteristics of rigid, one-dimensional rough
surfaces which create backscatter containing spikes in the time domain. The
interarrival time and amplitude statistics of impulsive events were determined
numerically through Monte Carlo realizations of different surface types. For
each surface the far-field impulse response in backscatter was determined using
an exact integral equation method adapted from E. I. Thorsos [J. Acoust. Soc.
Am. 83, 78 (1988)]. The impulse responses were convolved with the source
spectrum to generate exact backscattered waveforms. Three sets of surfaces were
investigated. In the first set, surfaces with a Gaussian correlation function
were considered, which possess a single horizontal and vertical scale. In the
second set, surfaces with a multiscale, power-law spectral density were
investigated. The third set consisted of surfaces made up of adjacent straight
line segments, or facets. The co-ordinates of the vertices of each facet were
randomized through a discrete stochastic process. The results have provided
insight into the physical mechanisms which generate spikes in the time domain
and helped distinguish the contribution that localized scatterers make versus
those that result from random interference of nonadjacent points on the surface.
[Work sponsored by the Office of Naval Research.]

ASA 132nd meeting - Hawaii, December 1996