N. Neretti is with the Institute for Brain and Neural Systems and Physics Department, Brown University, Providence RI 02912. N. Intrator is with the Institute for Brain and Neural Systems and Physics Department, Brown University, Providence RI 02912, and is on leave from Tel-Aviv University. L. N Cooper is with the Physics Department, Institute for Brain and Neural Systems and Neuroscience Depa...

Shallow water acoustics and the performance of sonar systems in littoral environments are critical areas of interest to the US Navy. In response to this, the Office of Naval Research sponsored a series of acoustics experiments in the East and South China Seas, hereafter referred to as ASIAEX. Components of these experiments included studies of shallow water reverberation, geoacoustic properties...

A functional similarity is described between cells of an occupancy grid for robot sonar, and integrate-and-re neurons of an artiicial neural net. Using this analogy, a new grid-based mapping system for robot sonar is described, which makes use of the neural concepts of receptive elds and recurrent connections. The performance of the new network is compared to that of a previous Bayesian grid-ba...

Many mobile robots use Polaroid ultrasonic sensors for obstacle avoidance. This paper describes the experimental characterization of these sensors using a unique, fully automated testbed system. Using this testbed, we gathered large data sets of 5,000-16,000 data points in every experiment for characterization purposes; in a repeatably fashion and without human supervision. In the experimental ...

Foraging and flight behavior of echolocating bats were quantitatively analyzed in this study. Paired big brown bats, Eptesicus fuscus, competed for a single food item in a large laboratory flight room. Their sonar beam patterns and flight paths were recorded by a microphone array and two high-speed cameras, respectively. Bats often remained in nearly classical pursuit (CP) states when one bat i...

In this paper we present a time-frequency approach for acoustic seabed classification. Work reported is based on sonar data collected by the Volume Search Sonar (VSS), one of the five sonar systems in the AN/AQS-20. The Volume Search Sonar is a beamformed multibeam sonar system with 27 fore and 27 aft beams, covering almost the entire water volume (from above horizontal, through vertical, back ...

Exploring and analyzing oceanographic sonar data is a difficult task due to the extreme ratios in the dimensions of the data. While sonar data may consist of many hundreds of thousands of sonar pings coving hundreds of kilometres, the ocean depth of the data is at a much lower resolution. As a result, visual representations of the sonar data (echograms) are normally shown as long and narrow rib...

Sequences with good correlation properties have been widely adopted in modern communications, radar and sonar applications. In this paper, we present our new findings on some constructions of single H-ary Golay sequence and 4-QAM Golay complementary sequence with a large zero autocorrelation zone, where H ≥ 2 is an arbitrary even integer and q ≥ 2 is an arbitrary integer. Those new results on G...

We present in this article a new evaluation method for classification and segmentation of textured images in uncertain environments. In uncertain environments, real classes and boundaries are known with only a partial certainty given by the experts. Most of the time, in many presented papers, only classification or only segmentation are considered and evaluated. Here, we propose to take into ac...

Introduction The estimation of fish abundance by the echo-integrator method requires a sonar that has been accurately calibrated. This may be done by measuring the signal received from a target whose acoustic properties are known. Several kinds of metal spheres have been used as calibration targets, in particular brass (Forbes, Simmonds and Edwards, 19801, copper (Foote, et a/., 1981) and tungs...