Most marine mammal- strandings coincident with naval sonar exercises have involved Cuvier's beaked whales (Ziphius cavirostris). We recorded animal movement and acoustic data on two tagged Ziphius and obtained the first direct measurements of behavioural responses of this species to mid-frequency active (MFA) sonar signals. Each recording included a 30-min playback (one 1.6-s simulated MFA sona...

Some of the differences between broadband and narrowband sonar systems applied in fisheries hydroacoustics are examined. Following a brief discussion of the advantages and disadvantages of broadband sonar, three different aspects of narrowband and broadband sonar systems are compared: detection, Doppler processing, and split-beam localization. Summaries are provided that compare representative ...

Information obtained by the ultrasonic sensor is influenced by the characteristics of the sensing system such as sensitivity, directivity and so on. In order to investigate its influence, we constructed two ultrasonic ranging systems of which characteristics differs from each other and examined their performance such as obstacle detectability and resultant sonar map.

Résumé. Ce papier présente une application pour le recalage et la fusion d’images sonar classifiées. Nous adaptons ici la méthode présentée dans un précédent papier à des données multivues. Pour la caractérisation de fond marin, nous avons besoin de fusionner des images sonar multivues afin d’améliorer les résultats. Néanmoins, avant de pouvoir fusionner ces images, il faut les recaler. Notre a...

Résumé. Nous présentons dans ce papier des approches de fusion d’informations haut niveau applicables pour des données numériques ou des données symboliques. Nous étudions l’intérêt des telles approches particulièrement pour la fusion de classifieurs. Une étude comparative est présentée dans le cadre de la caractérisation des fonds marins à partir d’images sonar. Reconnaı̂tre le type de sédiment...

Military sonars must detect, localize, classify, and track submarine threats from distances safely outside their circle of attack. However, conventional pulsed active sonars (PAS) have duty cycles on the order of one percent which means that 99% of the time, the track is out of date. In contrast, high duty cycle sonars (HDC) have duty cycles approaching 100% which enable near-continuous updates...

Military sonars must detect, localize, classify, and track submarine threats from distances safely outside their circle of attack. However, conventional pulsed active sonars (PAS) have duty cycles on the order of one percent which means that 99% of the time, the track is out of date. In contrast, high duty cycle sonars (HDC) have duty cycles approaching 100% which enable near-continuous updates...

Military sonars must detect, localize, classify, and track submarine threats from distances safely outside their circle of attack. However, conventional pulsed active sonars (PAS) have duty cycles on the order of one percent which means that 99% of the time, the track is out of date. In contrast, high duty cycle sonars (HDC) have duty cycles approaching 100% which enable near-continuous updates...