ACOUSTIC CONCENTRATOR FOR TRAWL FISH CATCHING Russian patent published in 2001 - IPC

FIELD: trawl fishing equipment. SUBSTANCE: acoustic concentrator has carrier towed behind trawl and rotating about its axis of rotation for creating elongate, periodically interrupted acoustic field embracing trawl and zone in front of trawl. Acoustic field is created by acoustic emitter controlled by program unit for setting up control signal programs. Acoustic concentrator has timer and vertical plane sensor, which are connected to program unit. Timer generates sequence of pulses blocking output signals of program unit, with program being changed upon expiration of each pause of program unit. Pulse and pause time magnitudes are of the order of minutes. Vertical plane sensor forms signal for generating four versions of acoustic field section configurations used in different trawling methods (bottom, variable-depth or other trawling methods). Vertical plane sensor has pendulum formed as disk with weight and opening at opposite edge of disk. Eight light sensors are positioned around disk at the level of opening, each composed of light-emitting diodes and light cells positioned at opposite sides of disk and free of mechanical connection with it. Four light sensors are arranged symmetrically to vertical line, with two sensors on each diametrically opposed disk edge, on sector boundary lines at an angle of about 20 deg, and four light sensors in similar position relative to horizontal line at boundary lines of sectors at angles of about Q, where Q is angle of acoustic emitter antenna directivity characteristics. Predetermined four pairs of light diodes are connected to different contacts of switch. As a result of short-time acoustic action (minutes) in alternation with pauses, after which emitted signal spectrum is changed, adaptivity of fish in trawl catching zone to increased intensity fields is excluded. EFFECT: simplified adjustment of fittings for different trawling methods and increased trawling efficiency. 2 cl, 4 dwg