Disguised Bionic Sonar Signal Waveform Design with Its Possible Camouflage Application Strategy for Underwater Sensor Platforms

IEEE The covertness of an active sonar is a very important issue and the sonar signal waveform design problem is studied to improve covertness of the system. Many marine mammals produce call pulses for communication and echolocation, and existing interception systems normally classify these biological signals as ocean noise and filter them out. Based on this, a disguised sonar signal waveform design approach with its camouflage application strategy for underwater sensor platforms is proposed by utilizing bio-inspired steganography. We first construct bionic sonar signal waveforms which are very close to the true whale whistle, and then embed these constructed bionic sonar signal waveforms into the true whale call trains to hide the real sonar signal waveforms. According to the time-frequency (TF) structure of the true whale whistle, a bionic sonar signal model is established to generate the proposed sonar signal waveforms. A single sonar signal is used to measure the range of the target and a combination of two sonar signals is utilized for measuring its speed. A high-performance range and speed measurement algorithm is deduced in detail. Based on the constructed signal waveforms and the characteristics of false killer whale call trains, a camouflage application strategy is designed to improve the camouflage ability of the sonar signal sequence. Finally, simulation results are provided to verify the performance of the proposed method

Whistle detection and classification for whales based on convolutional neural networks

Passive acoustic observation of whales is an increasingly important tool for whale research. Accurately detecting whale sounds and correctly classifying them into corresponding whale species are essential tasks, especially in the case when two species of whales vocalize in the same observed area. Whistles are vital vocalizations of toothed whales, such as killer whales and long-finned pilot whales. In this paper, based on deep convolutional neural networks (CNNs), a novel method is proposed to detect and classify whistles of both killer whales and long-finned pilot whales. Compared with traditional methods, the proposed one can automatically learn the sound characteristics from the training data, without specifying the sound features for classification and detection, and thus shows better adaptability to complex sound signals. First, the denoised sound to be analyzed is sent to the trained detection model to estimate the number and positions of the target whistles. The detected whistles are then sent to the trained classification model, which determines the corresponding whale species. A GUI interface is developed to assist with the detection and classification process. Experimental results show that the proposed method can achieve 97% correct detection rate and 95% correct classification rate on the testing set. In the future, the presented method can be further applied to passive acoustic observation applications for some other whale or dolphin species

Synthesis and modification of cetacean tonal sounds for underwater bionic covert detection and communication

For most conventional bionic signal design methods, they cannot construct high-similarity bionic signals to match those complex cetacean sounds because they are only based on relatively simple bionic signal models. Besides, although very few methods based on the weighted signal superposition technology can construct high-similarity bionic signals, it’s very difficult to adjust relevant parameters to match different cetacean sounds or synthesize other desired bionic signals. To solve these problems, firstly, two bionic signal models are proposed individually to mimic cetacean sounds with a simple time-frequency (TF) structure, and then they are combined to mimic cetacean sounds with complex TF structures based on a designed piecewise construction strategy. Based on the two models, the parameters of the synthesized bionic signals can be adjusted to improve detection and communication performance of the bionic signal s. The experimental results show that the Pearson correlation coefficient (PCC) results between 13 true cetacean sounds and their corresponding bionic signals are higher than 0.97, and 11 results of them are no less than 0.99. Four key performance indicators of a bionic signal are improved by more than 40% when bandwidth increases by 1kHz. Experimental results demonstrate that the proposed method cannot only efficiently imitate all kinds of simple and complex cetacean tonal sounds with high similarity, but also construct a variety of the same type of bionic signals by simply adjusting model parameters. In addition, the proposed method can also be applied to other areas, such as constructing a new cetacean sound database and so on

Global Security, Climate Change, and the Arctic

This issue of Swords and Ploughshares examines the complex set of global security challenges that are emerging as a result of warmer temperatures and melting ice in the Arctic region. For policymakers and analysts alike, the contemporary Arctic presents a particularly acute convergence of compelling problems and opportunities related to global security, foreign affairs, climate change, environmentalism, international law, energy economics, and the rights of indigenous populations. The goals of this publication are two-fold: to provide thoughtful analysis of recent developments in the Arctic both from scientific and geopolitical perspectives; and to offer careful and informed assessments of how evolving conditions in the Arctic might impact the broader global security framework and relations between the international actors involved, not to mention the region’s inhabitants and ecosystem. The articles in this issue were contributed by each of four panelists invited by the Program in Arms Control, Disarmament, and International Security (ACDIS), the European Union Center, and the Russian, East European, and Eurasian Center at the University of Illinois to participate in a November 2009 symposium entitled “Global Security, Climate Change, and the Arctic: Implications of an Open Northwest Passage.” The symposium and this publication were supported through grants to the host centers from the European Commission, the US Department of Education (Title VI international education program), and the John D. and Catherine T. MacArthur Foundation.published or submitted for publicationnot peer reviewe

Underwater Celestial Navigation Using the Polarization of Light Fields

Global-scale underwater navigation presents challenges that modern technology has not solved. Current technologies drift and accumulate errors over time (inertial measurement), are accurate but short-distance (acoustic), or do not sufficiently penetrate the air-water interface (radio and GPS). To address these issues, I have developed a new mode of underwater navigation based on the passive observation of patterns in the polarization of in-water light. These patterns can be used to infer the sun__s relative position, which enables the use of celestial navigation in the underwater environment. I have developed an underwater polarization video camera based on a bio-inspired polarization image sensor and the image processing and inference algorithms for estimating the sun__s position. My system estimates heading with RMS error of 6.02_ and global position with RMS error of 442 km. Averaging experimental results from a single site yielded a 0.38_ heading error and a 61 km error in global position. The instrument can detect changes in polarization due to a 0.31_ movement of the sun, which corresponds to 35.2 km of ground movement, with 99% confidence. This technique could be used by underwater vehicles for long-distance navigation and suggests additional ways that marine animals with polarization-sensitive vision could perform both local and long-distance navigation

Underwater Vehicles

For the latest twenty to thirty years, a significant number of AUVs has been created for the solving of wide spectrum of scientific and applied tasks of ocean development and research. For the short time period the AUVs have shown the efficiency at performance of complex search and inspection works and opened a number of new important applications. Initially the information about AUVs had mainly review-advertising character but now more attention is paid to practical achievements, problems and systems technologies. AUVs are losing their prototype status and have become a fully operational, reliable and effective tool and modern multi-purpose AUVs represent the new class of underwater robotic objects with inherent tasks and practical applications, particular features of technology, systems structure and functional properties

Autonomous robot systems and competitions: proceedings of the 12th International Conference

This is the 2012’s edition of the scientific meeting of the Portuguese Robotics Open (ROBOTICA’ 2012). It aims to disseminate scientific contributions and to promote discussion of theories, methods and experiences in areas of relevance to Autonomous Robotics and Robotic Competitions. All accepted contributions are included in this proceedings book. The conference program has also included an invited talk by Dr.ir. Raymond H. Cuijpers, from the Department of Human Technology Interaction of Eindhoven University of Technology, Netherlands.The conference is kindly sponsored by the IEEE Portugal Section / IEEE RAS ChapterSPR-Sociedade Portuguesa de Robótic