MULTIFREQUENCY DOPPLER METHOD FOR MEASURING THE SPEED OF CURRENTS IN THE AQUATIC ENVIRONMENT Russian patent published in 2023 - IPC G01S15/60 G01S15/58 

FIELD: hydroacoustics.

SUBSTANCE: acoustic methods of active location, the operation of which is based on the double Doppler effect, according to which the frequency of waves is shifted when they are reflected from moving bodies. In the multi-frequency Doppler method for measuring the speed of currents in the aquatic environment, the frequency shift of the received scattered wave is measured relative to the frequency of the emitted wave, and the speed of movement of the carrier of the wave source relative to the scattering surface is indirectly determined, and vice versa - the speed of movement of the scattering surface relative to the source. In the claimed multi-frequency pulsed Doppler method, these measurements are proposed to be carried out at several multiple operating frequencies, which allows to select the required speed sensitivity, increase the accuracy of determining the speed of the carrier vessel both in shallow water relative to the bottom and in deep water regions relative to the aquatic environment. Comparison of Doppler shifts for different depths on working signals of multiple frequencies makes it possible to additionally obtain refined data on the distribution of directions and magnitudes of sea current velocities in the sound-scattering layers of the aquatic environment in depth, i.e. to investigate in the pulsed mode the fine structure of the spatio-temporal characteristics of the velocity field of sea currents.

EFFECT: increasing the speed sensitivity of the Doppler method through the use of a non-linear self-action effect that occurs when a powerful ultrasonic signal of finite amplitude propagates in an aquatic environment.

2 cl, 3 dwg