Patent ID: 7934432
Filing Date: 2011-05-03
Classification: A61B,G01F

Abstract:
1. A method for measuring the run time of an ultrasonic pulse in the determination of the flow velocity of a gas, the method comprising the steps of: providing a breathing gas volume flow sensor with a flow duct having a measuring section; arranging the measuring section in parallel to or at an angle smaller than 90° to the flow duct; providing the measuring section with an ultrasound transmitter and an ultrasound receiver; triggering an ultrasonic pulse at the ultrasound transmitter by a transmitting pulse such that the ultrasound receiver sends a receiving signal and the receiving signal is recorded as a first receiving signal data record as a function of time after the transmitting pulse; forming a correlation function of the first receiving signal data record with a first sample data record; and determining a run time of the ultrasonic pulse from the point in time of a correlation maximum.