Article

Article title TO ASSESS THE LEVEL OF THE REVERB SIGNAL SUPPRESSION WITH PARTLY-COHERENT PROCESSING OF ECHO SIGNALS
Authors A.A. Illarionov, S.V. Kozlovski, A.B. Korjakin, S.E. Shcherba
Section SECTION I. ACOUSTICS AND HYDROACOUSTICS
Month, Year 12, 2015 @en
Index UDC 656.61.087: 623.82
DOI
Abstract The article reviews the estimation of the reverberation interference levels in relation to the use of complex probing signals and partially coherent hydroacoustic information processing. The method of echo-signal processing involves the coherent reception within K- signal portions and subsequent incoherent reception of their output effects. The approximate technique for estimation of reverberation at the reception channel output with regard to the type of probing signal and parameters of partially coherent processing (PCP) is developed. The technique is based on the estimation and using duration of compressed echo-signal after the PCP at the sonar reception channel output instead of probing signal duration. Modeling (using MATLAB-7) in relation to the noise- like (phase-manipulated) probing signal with parameters: duration – 1 sec and band – 1000 Hz for the coherent processing and PCP was made. Sections in frequency and time areas of the ambiguity function of current signal for different K- values are built as a result of modeling. Parameters of the echo-signal ambiguity function with PCP are defined: sidebar level, major lobe width by time, major lobe width by frequency. The approximation of the dependence of the output signal duration from the number of K-portions echo-signal is divided for the coherent processing is obtained on the basis of modeling. This dependence is the basis for estimation of compressed at the reception channel output signal duration. An example of assessing reduction of the reverberation (bottom component) by using PCP (K=10) of the complex probing signal compared with incoherent processing of current signal is represented. The value of the compressed after the PCP signal duration was 5 ms that reduces bottom reverberation level at the sonar output channel by 23 dB. A similar result is achieved in the case of exposure of surface and volumetric components of the reverberation interference. Based on the above approach estimation of hydrolocation channel noise stability under the impact of prevailing reverberation interference (bottom, surface and volumetric components) with partial coherent processing of complex signals is possible.

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Keywords Reverberation; the difficult signal; partially-coherent processing.
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