Time-of-flight estimation using extended matched filtering

The problem considered is the estimation of the ToF (time-of-flight) of an acoustic tone burst in a reflective environment. Secondary echoes cause a complex interference pattern. Only the ToF of the first echo is of interest. Conventional matched filtering (MF) cannot cope with overlapping echoes. An explicit model for overlapping echoes leads to a generalized MF consisting of a parallel bank of filters rather than just a single filter. The new method is evaluated with a dataset of 150 records of observed waveforms using 3-fold cross validation

Autonomous intrusion detection information system

Abstract – Implementation of security arrangements for insecure premises, for example, for temporary exhibitions or infrequent public events, usually results in substantial security personnel costs which can be potentially reduced by employing an easily installable ad hoc intrusion detection information system. In the paper we described the architecture, design and experimental results for a fully prototyped information system that utilizes ultrasonic sensors operating in the pulse echo mode for the perimeter control and ZigBee transceivers for wireless networking. The system consists of inexpensive autonomous sensor nodes with the component cost of less than £25 and a control terminal with a graphical user interface controlled by a touch screen. The nodes are programmed wirelessly to detect intrusion within any user set distance up to the operating distance of the node, and can operate unattended for days. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2877

The development and testing of a parametric SONAR system for use in sediment classification and the detection of buried objects

This thesis describes the work carried out in the development and testing of parametric sonar systems for application in the fields of seabed sediment characterisation and classification, and the detection of seabed embedded objects. Parametric sonar systems offer a number of advantages over conventional sonar systems. This is especially true of the conflicting requirements of both seabed delineation and penetration required for a practical sub-seabed profiling system. Echoes from sub-bottom layers vary in strength dependent on both the boundary acoustic reflectivity and the absorption characteristics of the layer above. Absorption effects are usually frequency dependent, allowing better penetration to lower frequency signals. [Continues.

The use of active sonar to study cetaceans

Cetacean species face serious challenges worldwide due to the increasing noise pollution brought to their environment by human activities such as seismic exploration. Regulation of these activities is vaguely defined and uncoordinated. Visual observations and passive listening devices, aimed at preventing conflicts between human wealth and cetaceans’ health have some fundamental limitations and may consequently fail their mitigation purposes. Active sonar technology could be the optimal solution to implement mitigation of such human activities. In my thesis, the proper sonar unit was used to test the feasibility to detect cetaceans in situ. Omnidirectional sonars could be the optimal solution to monitor the presence of cetaceans in the proximity of potential danger areas. To use this class of sonar in a quantitative manner, the first step was to develop a calibration method. This thesis links in situ measurements of target strength (TS) with variation trends linked to the behavior, morphology and physiology of cetacean. The butterfly effect of a cetacean’s body was described for a fin whale insonified from different angles. A relationship between whale respiration and TS energy peaks was tested through a simple prediction model which seems very promising for further implementation. The effect of lung compression on cetacean TS due to increasing depth was tested through a basic mathematical model. The model fit the in situ TS measurements. TS measurements at depth of a humpback whale, when post-processed, correspond to TS measurements recorded at the surface. Sonar technology is clearly capable of detecting whale foot prints around an operating vessel. Sonar frequency response shows that frequencies between 18 and 38 kHz should be employed. This work has established a baseline and raised new questions so that active sonar can be developed and employed in the best interest for the whales involved in potentially harmful conflicts with man

The Soundscape Planning of Mountain Park in Holyoke, Massachusetts

The soundscape of a place is simply its acoustic environment, with the listener situated within the center of the sonic landscape (Porteous and Mastin, 1985). Soundscapes can be adjusted with proper planning, site analysis and design. Often overlooked by design and planning professionals, sounds are a part of the biological, social and spiritual context which needs to be considered if good outdoor environments are to be provided (Hedfors, 2003). With its close proximity to the Whiting Street Reservoir and Holyoke Range, Mountain Park provides a terrific opportunity for an outdoor amphitheater, a cultural resource deeply needed in Western Massachusetts. Significant landform and vegetation on site will greatly contribute to the acoustic opportunities and challenges of the site, while Interstate 91 provides an opportunity to mitigate the challenge of nearby noise pollution

Deep-diving beaked whales dive together but forage apart

Funding: Data collection and analysis were performed with funds from the U.S. Office of Naval Research (ONR), the US National Oceanographic Partnership Program (NOPP), the US Strategic Environmental Research Development Program (SERDP) and the Spanish Government National Projects CETOBAPH (CGL2009-13112) and DEEPCOM (CTM2017-88686-P). J.A.T. is currently the recipient of a FPU Doctoral Scholarship (FPU16/00490) from the Spanish Ministry of Universities. M.J. is supported by the Aarhus University Research Foundation and the EU H2020 research and innovation programme under Marie Skłodowska-Curie grant 754513. P.A. is funded by an Agustín de Bethencourt fellowship from the Cabildo Insular de Tenerife and NAS by a Ramón y Cajal fellowship from the Spanish Government. V.E.W. is funded by a University of Auckland Doctoral Scholarship. C.J.P.G. is partially funded by the Ministry of Science and Innovation (MICINN) of Spain under Grant PID2019-110442GB-I00. T.A.M. thanks partial support from CEAUL (funded by FCT - Fundação para a Ciência e a Tecnologia, Portugal, through the project UIDB/00006/2020).Echolocating animals that forage in social groups can potentially benefit from eavesdropping on other group members, cooperative foraging or social defence, but may also face problems of acoustic interference and intra-group competition for prey. Here, we investigate these potential trade-offs of sociality for extreme deep-diving Blainville′s and Cuvier's beaked whales. These species perform highly synchronous group dives as a presumed predator-avoidance behaviour, but the benefits and costs of this on foraging have not been investigated. We show that group members could hear their companions for a median of at least 91% of the vocal foraging phase of their dives. This enables whales to coordinate their mean travel direction despite differing individual headings as they pursue prey on a minute-by-minute basis. While beaked whales coordinate their echolocation-based foraging periods tightly, individual click and buzz rates are both independent of the number of whales in the group. Thus, their foraging performance is not affected by intra-group competition or interference from group members, and they do not seem to capitalize directly on eavesdropping on the echoes produced by the echolocation clicks of their companions. We conclude that the close diving and vocal synchronization of beaked whale groups that quantitatively reduces predation risk has little impact on foraging performance.PostprintPeer reviewe