FIELD: measurement technology. SUBSTANCE: method is used to measure current speed in river, open bed of washing gallery and tube of large inner diameter. Amplitude modulation of undamped harmonic ultrasonic sinusoidal wave fc with signal of frequency fм, is carried out, propagation/reception of amplitude-modulated signal is conducted and wave of amplitude modulation is used to measure propagation tie of ultrasound. According to second variant phase difference is determined. In this case amplitude modulation of ultrasonic wave by signal with frequency fм determined beforehand is carried out. If phase difference between ultrasonic waves propagated in directions coinciding with current speed or opposite to it exceeds π radian then transmission/reception of amplitude-modulated signals is conducted, phase difference between amplitude-modulated signals is measured. Then phase difference between ultrasonic waves is measured again. EFFECT: increased authenticity and measurement accuracy and expanded application field. 4 cl, 6 dwg
