Ultrasonic emissions of bats are directional and delimit the echo-acoustic space. Directionality is quantified by the aperture of the sonar beam. Recent work has shown that bats often widen their sonar beam when approaching movable prey or sharpen their sonar beam when navigating through cluttered habitats. Here we report how nose-emitting bats, Phyllostomus discolor, adjust their sonar beam to...

An experimental ultrasound scanning sonar has been developed that uses a phased ultrasonic transducer array to image objects through the air. The sonar generates arbitrary long duration broadband signals and uses pulse compression to achieve a high range resolution and a high signal to noise ratio. This paper considers using the sonar in an inverse synthetic aperture side-scan configuration, wh...

Chronic neural recordings were taken from the midbrain superior colliculus (SC) of echolocating bats while they were engaged in one of two distinct behavioral tasks: virtual target amplitude discrimination (VTAD) and real oscillating target tracking (ROTT). In the VTAD task, bats used a limited range of sonar call features to discriminate the amplitude category of echoes, whereas in the ROTT ta...

The sonar beam of an echolocating bat forms a spatial window restricting the echo information returned from the environment. Investigating the shape and orientation of the sonar beam produced by a bat as it flies and performs various behavioral tasks may yield insight into the operation of its sonar system. This paper presents recordings of vertical and horizontal cross sections of the sonar be...

Traditional approaches to AUV collision avoidance involve the adaptation of COTS electronic scanning sonars that have been designed for applications where low power is not a consideration. This has an adverse impact on the endurance and performance of the AUV. The navigation and obstacle avoidance processing is typically performed by the vehicle control processor, acting on large volumes of dat...

There is increasing concern that human-produced ocean noise is adversely affecting marine mammals, as several recent cetacean mass strandings may have been caused by animals' interactions with naval 'mid-frequency' sonar. However, it has yet to be empirically demonstrated how sonar could induce these strandings or cause physiological effects. In controlled experimental studies, we show that mid...

In this paper, we are interested in inferring the sources of various types of sonar features typically observed by a mobile robot. After a brief discussion of terrestrial sonar sensing, we develop a set of operators that associates arc-shaped features extracted from sonar scans with real world primitives. Our classi cation scheme is probabilistic and is based on empirical data: the condence of ...

Affected by the residual of time varying gain, beam patterns, angular responses, and sonar altitude variations, radiometric distortion degrades the quality of side-scan sonar images and seriously affects the application of these images. However, existing methods cannot correct distortion effectively, especially in the presence of seabed sediment variation. This study proposes a new radiometric ...

There has been an increasing interest in studying animal behaviours [1]. In the EU funded project “ChiRoPing: Developing Versatile and Robust perception using Sonar Systems that Integrate Active Sensing, Morphology and Behaviour” [2], the interest is placed on Chiroptera (bats) as bats are the nature’s expert in active sonar sensing [3]. Study of bats’ behaviour is not only of biological intere...

UNITES is a unique, interdisciplinary team with expertise spanning the environment (physical oceanography and bottom geology), ocean acoustics (propagation, ambient noise, reverberation and signal processing), and tactical sonar systems. The overall goals of the research are to enhance the understanding of the uncertainty in the ocean environment (including the sea bottom), characterize its imp...