FIELD: underwater acoustics. SUBSTANCE: invention refers to underwater acoustic instruments designed to measure depth. The echo sounder includes synchronizing unit, generator of radio pulses, amplifier, detector, threshold unit, unit measuring time intervals and indicator connected in series, piezovibrator connected to generator of radio pulses and amplifier. Echo sounder is supplemented with unit for time automatic adjustment of gain control connected with first input to second output of synchronizing unit, with second input to second output of unit measuring time intervals and with output to second input of amplifier. EFFECT: enhanced noise immunity and accuracy of portable echo sounder under different conditions of operation. 3 cl, 7 dwg
