Ilkka Karasalo

Learn More
A benchmark problem on atmospheric sound propagation over irregular terrain has been solved using a stable fourth-order accurate nite di erence approximation of a highdelity acoustic model. A comparison with the parabolic equation method and ray tracing methods is made. The results show that ray tracing methods can potentially be unreliable in the presence(More)
This paper describes methodology and results from a model-based analysis of data on sound transmission from controlled sound sources at sea to a 10-km distant shore. The data consist of registrations of sound transmission loss together with concurrently collected atmospheric data at the source and receiver locations. The purpose of the analysis is to assess(More)
A submarine on patrol needs to know how far it can be detected by active sonar. In order for such sonar performance calculations to be useful the target strength (TS) of the submarine must be known. Measurements done in deep water indicate that TS can vary as much as 20 dB as a function of aspect angle. This corresponds to a doubling of the detection(More)
Estimates of the noise source spectra of ships based on long term measurements in the Baltic sea are presented. The measurement data were obtained by a hydrophone deployed near a major shipping lane south of the island Öland. Data from over 2,000 close-by passages were recorded during a 3 month period from October to December 2014. For each passage,(More)
Ehsan Zamanizadeh, João Gomes Institute for Systems and Robotics Instituto Superior Técnico (IST) Technical University of Lisbon (UTL) 1049–001 Lisbon, Portugal Email: {ezamanizadeh, jpg}@isr.ist.utl.pt José M. Bioucas-Dias Instituto de Telecomunicações Instituto Superior Técnico (IST) Technical University of Lisbon (UTL) 1049–001 Lisbon, Portugal Email:(More)
This article focuses on computations of low frequency sound propagation from an off-shore wind farm. Two different methods for sound propagation calculations are combined with meteorological data for every 3 hours in the year 2010 to examine the varying noise levels at a reception point at 13 km distance. It is shown that sound propagation conditions play a(More)
  • 1