Patent ID: 7614310

Claim:
A method for determining the transit time (t) of an ultrasonic signal ( 15 ) from an ultrasonic sensor ( 6 ) that was launched into a measurement path (L) by an ultrasonic converter (A, B); the phase shift (Δφ) of the ultrasonic signal ( 15 ) is determined relative to a reference timing signal ( 8 ), and a remainder (r(t)) is determined as a measure of the transit time (t) of the ultrasonic signal ( 15 ), wherein the phase shift (Δφ) is determined using a quadrature demodulation scheme, with which the received ultrasonic signal ( 15 ) is inverted, in a segmented manner, using a timing signal ( 8 ) and a phase-shifted timing signal ( 9 ), and the remainder (r(t)) is determined based on a characteristic quantity (t s ) of the ultrasonic signal ( 15 ).