METHOD OF MEASURING THICKNESS OF ICE FROM UNDERWATER VEHICLE Russian patent published in 2014 - IPC G01B17/02 

FIELD: physics, acoustics.

SUBSTANCE: invention relates to hydroacoustics and can be used in navigation devices for detecting ice and measuring characteristics thereof. The method for automatic measurement of ice thickness from an underwater vehicle involves measuring the immersion depth H of the vehicle, generating and emitting a low-frequency signal with duration T<2H/C, where H is the immersion depth of the vehicle, C is the speed of sound, and frequency F<1000 Hz, generating and emitting a high-frequency signal with frequency F<1200 Hz/d(m), where d is the thickness of fresh ice in metres, duration M=10/f, wherein the high-frequency signal is emitted at points which correspond to amplitude of the low-frequency signals being equal to zero, separately receiving signals, measuring the time t_i when the amplitude of the low-frequency signal is equal to zero, where i is the measurement index number, measuring the arrival time of the leading edge of the high-frequency signal Q_i and if the measurement index numbers match, the time difference Q_i-t_i is calculated, the lag phase of the low-frequency signal is calculated using the formula θ=(Q_i-t_i)180°/M. Ice thickness is determined using the formula h_i=θ/η, where η is refined based on experimental evaluation results (approximately η=500), and the final estimate of ice thickness is defined as the average of all measurements of ice thickness over the duration of the low-frequency transmission.

EFFECT: high accuracy and providing automatic measurement of thickness of fresh ice.

3 cl, 1 dwg