Optimising the Sounding Pulse of the Rotational Directional Transmission Sonar
To increase a sonar's source level, continuous or stepwise rotational directional transmission (RTD) is used. Continuous beam rotation has already been employed in analogue sonars. Because controlled phase shifts could not be adjusted precisely, the result was a sounding pulse which apart from the main maximum also carried a number of additional relatively high level side lobes. Stepwise beam rotation works well in a digital technology, it is not, however, free from drawbacks. Adjacent transmitting beams overlap slightly resulting in the transmission of a number of varying amplitude pulses rather than a single pulse. Modern microprocessor technology combined with weighting windows and a continuous beam rotation yields a single sounding pulse with a negligible level of side lobes. Unfortunately, for short sounding pulses and a quick rotation of the transmitting beam, the shape of the pulses suffers. The authors of the paper introduced an additional frequency and phase adjustments of signal excitation which results in a short, single sounding pulse for the entire sector of the sonar. Proposed methods can by realised by the use of modern DDS (direct digital synthesis) technology.
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Document Type: Research Article
Publication date: 2002-09-01
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- Acta Acustica united with Acustica, published together with the European Acoustics Association (EAA), is an international, peer-reviewed journal on acoustics. It publishes original articles on all subjects in the field of acoustics, such as general linear acoustics, nonlinear acoustics, macrosonics, flow acoustics, atmospheric sound, underwater sound, ultrasonics, physical acoustics, structural acoustics, noise control, active control, environmental noise, building acoustics, room acoustics, acoustic materials, acoustic signal processing, computational and numerical acoustics, hearing, audiology and psychoacoustics, speech, musical acoustics, electroacoustics, auditory quality of systems. It reports on original scientific research in acoustics and on engineering applications. The journal considers scientific papers, technical and applied papers, book reviews, short communications, doctoral thesis abstracts, etc. In irregular intervals also special issues and review articles are published.
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