FIELD: acoustic location systems. SUBSTANCE: echo ice detection unit has synchronizer 1, basic double frequency radiopulse generator 2, reception/radiation commutator 3, high-frequency back aerial 4, low-frequency receiving aerial 5, the first selective amplifier 5, phase detector 7, selective amplifier 8, square-law detector 9, lower frequency filter 10, averaging circuit 11, pulse former 12, registrar 13, the first amplifier-restrictor 14, the first detector 15, the second amplifier-restrictor 16, the second detector 17, coincidence circuit 18, the second former 19 and switch 20. Ice is detected onto water surface by means of difference of echo-signals reflected from water/ice and water/air boundaries. Difference in echo-signals is achieved due to the fact, that when reflecting from water/air boundary the phase of reflected wave is inverted. When water/ice boundary is studied, wave reflects without changes in phase. Reference signal is used for measuring phase. EFFECT: improved reliability of ice detection; improved truth of results of measurements. 3 dwg
