Browsing by Author "Rodionov, A. A."

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Bearing estimation of a source with complicated spectrum using a moving sparse antenna array
(Видавництво Національного університету "Львівська політехніка", 2009) Korotin, P. I.; Rodionov, A. A.; Turchin, V. I.
Estimation of bearing of a narrowband source with the use of a sparse equidistant array usually turns out to be ambiguous. For a wideband source with smooth spectrum, this ambiguity can be overcome at the expense of decreasing the spatial resolution. At the same time, the ambiguity of bearing estimate of a narrowband source can be eliminated if the array is moving in respect to the source, and the well-known technique used in radars and sonars with synthetic aperture is used (in this case, a single receiver is enough). In the present paper, a scenario is analyzed when the source spectrum has a smooth wideband component and several narrowband components; such a spectrum is typical, for example, for underwater noise of ships. It is shown that a procedure of aperture synthesis applied to such a signal gives, under some conditions, the same result as conventional beamforming using a motionless array. This fact allows for effective separation of discrete components of the spectrum from its continuous part. Estimates of aperture synthesis duration allowing one to perform such a separation, as well as output signal-to-noise ratios, are presented.
Estimation of positions of local narrow-band sources on a ship hull usinga vertical antenna array
(Видавництво Національного університету "Львівська політехніка", 2009) Orlov, D. A.; Rodionov, A. A.; Turchin, V. I.
A method for estimation of positions of local narrow-band sources on a moving ship, allowing one to identify the mechanisms making the greatest contribution to its sound pressure level, is proposed in the paper. The actuality of this problem is related to strengthening the requirements imposed on the sound pressure level of ships because of ecological and other requirements. The method is based on space-time filtering of the signal received by the elements of a vertical antenna array. The ship is supposed to move straightly and uniformly at a short distance from the array; the track parameters are supposed to be known. The results of the method testing with the use of the data obtained in sea experiment are presented in the paper. The testing has shown that the source localizing precision is close to the theoretically achievable one. An analysis of the method error is performed in a wide frequency range using numerical modeling.