The development of SONAR (acronym: SOund Navigation And Ranging) systems started in the early 20th century inspired by the calamity of the Titanic in 1912. A system should be developed to prevent collision with icebergs. Since that time systems for a broad variety of applications such as navigation, fish finding, cartography, etc. have been developed and SONAR systems are extensively used in civil as well as military shipping. Next to active systems where emitted soundwaves are used to sense the environment by reflections, passive systems are available which are solely listening for waves emitted by the environment. In many available systems "classical" techniques like time-delay beamforming and the emission of correlated waveforms using all available sender elements are utilized. Next to that the operator needs to intervene to adopt the emitted waveforms and the processing chain to the environment and the awaited target type to achieve an optimal detection rate.
Recently so called cognitive SONAR-systems and in addition to that MIMO techniques are proposed. Both ideas should be combined to build an innovative more powerful system. While cognitive systems are sensing the environment and utilizing previous detection data to autonomously optimize emitted waveforms and the processing of the raw data to the situation, MIMO systems are emitting uncorrelated waveforms to achieve an improved illumination of the underwater channel and such virtual arrays with a higher number of elements. As the number of elements is related to the resolution of the system such systems are e.g. capable of an enhanced detection rate.
In the topic of underwater telephony the sound waves are used to transmit speech signals using either analog or digital techniques.
As the underwater channel adds a vast number of distortions to the transmitted signal (e.g. noise, echoes) the received signal quality is highly degraded.
These issues are not accounted in existing standards for analog/digital underwater communication systems so that digital signal processing techniques need to be developed and implemented under the constraint of compatibility with existing systems.
Our real-time channel simulation supports several send and receive hydrophones that can be placed in an underwater environement with a variety of adjustment possibilities, such as sound velocity profiles (depth dependent). In addition, wind speed and direction can be adjusted (both is fed into a statical model for creating a time and location dependent water surface and corresponding noise). Furthermore, several moving target can be simulated. The channel simulation is based on a restricted 3D ray tracing scheme, that allows freqeuency dependant ray parameters (e.g. reflection and attenuation). The channel simulator is based on our real-time framework KiRAT.
T. O. Wisch, T. Kaak, A. Namenas, G. Schmidt: Spracherkennung in stark gestörten Unterwasserumgebungen, Proc. DAGA 2018
T. Kaak, and G. Schmidt: An Introduction to Real-time Cognitive SONAR Systems Utilizing Novel MIMO Approaches, Proc. DAGA, Kiel, Germany, open access, 2017
A. Namenas, T. Kaak, and G. Schmidt: Real-time Simulation of Underwarter Acoustic Channels, Proc. DAGA, Kiel, Germany, open access, 2017
K. Pikora, F. Ehlers: Self-Tuning Active Sonar Signal Processing for a Towed Hydrophone Array During a Turn, Oceans 2015, Washington, USA
T. Claussen, V. D. Nguyen, U. Heute, G. Schmidt: A Real-time Cognitive-Sonar System for Diver Detection, MTS/IEEE Oceans 2015, Oktober 19-22, 2015, Washington D.C., USA
T. Claussen, V. D. Nguyen: Real-time Cognitive Sonar System with Target-optimized Adaptive Signal Processing through Multi-layer Data Fusion, IEEE 2015 International Conference on Multisensor Fusion and Integration for Intelligent Systems, September 14-16, 2015, San Diego, USA
M. Brötje, K. Pikora: Parameter estimation for multistatic active sonar using extended fixed points, Proc. International Conference on Information Fusion 2015, Washington, USA
T. Claussen, V. D. Nguyen, U. Heute, G. Schmidt: A Real-time MIMO System for Sonar Applications, Proc. DAGA 2015, March 16-19, 2015, Nuremberg, Germany
K. Pikora, F. Ehlers: Tracking Performance Loss due to False Associations of Contacts from Semi-Coherent Signal Processing Chains, Proc. International Conference on Information Fusion 2014, Salamanca, Spain
V. D. Nguyen, T. Claussen: Individual-Gating-by-Sorting in MHT, Proc. International Conference on Information Fusion 2014, Salamanca, Spain
R. Kreimeyer, S. Ludwig: Automatic Classification of Marine Mammals with Speaker Classification Methods, 3rd. International Conference on the Effects of Noise on Aquatic Life 2013, Budapest Hungary
S. Ludwig, R. Kreimeyer: Comparison of PAM Systems for Acoustic Monitoring and Further Risk Mitigation Application, 3rd. International Conference on the Effects of Noise on Aquatic Life 2013, Budapest Hungary
K. Pikora, F. Ehlers: Analysis of the FKIE Passive RADAR Data Set with GMPHD and GMCPHD , Proc. International Conference on Information Fusion 2013, Istanbul, Turkey
V. D. Nguyen, T. Claussen: Reduced Computational Complexity of Gating Procedures Using Sorting Algorithms , Proc. International Conference on Information Fusion 2013, Istanbul, Turkey
V. D. Nguyen: Small-Target Radar Detection and Tracking within the PITAS Hard- and Software Environment, Future Security Conference 2012, Bonn, Germany
R. Kreimeyer, Merkmalsextraktion von Klicklauten zur Erkennung von Meeressäugern, DAGA 2012, Darmstadt, Germany, 2012
R. Kreimeyer: Akustische Kommunikation - Der Natur abgeschaut, Tagung der Deutschen Wehrtechnischen Gesellschaft 2012, Kiel, Germany, 2012
V. D. Nguyen, Small-Target Radar Detection and Tracking within the PITAS Hard- and Software Environment, Future Security Conference 2012, Bonn, Germany, 2012
S. Ludwig, V. Peschko, D. Lorenzen, R. Kreimeyer, M. Knoll, U. Siebert, H.-V. Fiekas: Acoustic and Visual Survey of Cetaceans in the Azores Front Area, 26th Annual Conference of the ECS, Gallway, Ireland, 2012
R. Kreimeyer, Feature extraction of modulated marine-mammal sounds for species classification, ECUA 2012, Edinburgh, Scotland, 2012
R. Kreimeyer: Akustische Kommunikation - Der Natur abgeschaut, Tagung der Deutschen Wehrtechnischen Gesellschaft 2012, Kiel, Germany
K. Wilkens, V. D. Nguyen, U.Heute: Adaptive Clutter Density in Multi-Hypothesis Tracking, Proc. IEEE ISIF GI Workshop Sensor Data Fusion 2011, Berlin, Germany, 2011
K. Wilkens, T. Ludwig, H. Schmaljohann: New Developments for Multi-Hypothesis Tracking in Anti-Submarine Warfare, UDT Europe 2011, London, UK, 2011
A. Schulz, H. Schmaljohann, K. Wilkens, I. Nissen, C. Kubaczyk, W. Jans: Systems and Concepts for Networked ASW, Underwater Acoustics Measurements UAM 2011, Kos, Greece, 2011
K. Wilkens, M. Daun: A Gaussian Mixture Motion Model and Contact Fusion Applied to the Metron Data Set, Proc. International Conference on Information Fusion 2011, Chicago, USA, 2011
Dennis Küter, U. Heute: Aktive Sonardetektion mit einem selbstausrichtenden Array, Proc. DAGA 2011, Düsseldorf, Germany, 2011
K. Seget, A. Schulz, U. Heute: Multi-Hypothesis Tracking and Fusion Techniques for Multistatic Active Sonar Systems, Proc. International Conference on Information Fusion 2010, Edinburgh, Scotland, 2010