Patent ID: 8224621
Filing Date: 2012-07-17
Classification: G01F,G01N,G08B

Abstract:
1. A method of determining a time of flight of a signal transmitted between a transmitter and a receiver, said method comprising the steps of: at a signal transducer of the transmitter, generating a first ultrasonic signal comprising a plurality of cycles of a characteristic waveform feature; at the signal transducer of the transmitter, generating a second ultrasonic signal comprising a plurality of cycles of the characteristic waveform feature and further comprising a waveform modification being a phase shift in the cycle of a characteristic waveform feature introduced at a predetermined point in time of a duration of the second ultrasonic signal; receiving said first and second generated signals at the receiver; determining a time of reception of the introduced phase shift in the second ultrasonic signal by comparing the waveform of the first received signal to the waveform of the second received signal and determining a point of diversion between corresponding characteristic waveform features of the first and second received signals; determining a time of flight of the second ultrasonic signal based on the determined time of reception of the introduced phase shift and its time of generation.