FIELD: underwater acoustics.
SUBSTANCE: method can be used in fishing industry for detecting and identifying (species, quantitative and dimensional) of gathering of marketing bottom fish with swimming-bladder. Method consists in radiation of high-frequency pumping wave at the direction of bottom which waves have frequencies ω1 and ω2 to be close to resonant frequency ω0 of air bubbles being present at subsurface layer of water at the direction of bottom. In non-uniform water medium high-frequency pumping waves exhibit non-linear interaction at frequencies of ω1 and ω2 to form low-frequency wideband difference frequency Ω=ω1-ω2. Difference frequency Ω=ω1-ω2 is close to frequency Ωos of resonant absorption of sound absorbed by bottom fish's swimming-bladder. High-frequency wave is irradiated additionally with frequency ω3 being close to resonant frequency ωos of biological sound-dissipating layer which frequency interacts with wideband difference frequency wave Ω' reflected from gatherings of fish with swimming-bladder as well as with low-frequency wave of self-radiation of fish at frequency of Ω'' to form combination frequency waves of ω3± Ω' ω3± Ω''. After the procedure the signals with frequencies of ω3± Ω'and ω3± Ω''are received, detected and processed. According to the results of processing the decision of detection of marketing gathering of bottom fish with swimming-bladder at complex ground background is made and species, quantitative and dimensional characteristics of gathering are determined.
EFFECT: improved precision; increased reliability.
4 dwg
