(TOF) Time of flight is a ultrasound technique used for calculating of the distance to a target by using the timing of the returning echo from the target and the speed of sound in the medium between the target and the sensor. Time of flight is used in echo location and ultrasonic flowmeters.

B-scan comined with D-scan (D=Depth) is used to avoid image inhomogeneity. Different transmitter signals for each depth are applied and prefiltered pseudoinversely according to the transfer properties of the covering tissue. Pulse compression techniques with nonlinearly frequency modulated signals are used to gain the required energy for inverse filtering.
D-scan is a modified C-scan used in nondestructive testing with the display of amplitudes. In the 2D graphical presentation, time of flight values are displayed in the top view on a test surface.

See also A-Scan, B-Scan and C-Scan.

The echo location is the location of a target relative to the sensor face. The echo is located by measuring the time that it takes for a sound wave to travel to the target and be reflected back to the sensor.

See also Time of Flight.

A flowmeter is a device to measure velocity or volume of flow of liquids or gases passing a given point per unit of time.

See also Time of Flight.

A flowmeter derives an accurate measure of the transit time ; transit time (or time of flight) is the difference in time for an ultrasonic pulse to travel with the direction of flow and against it. With bi-directional illumination it is the time taken for an ultrasound pulse to travel from one transducer to another. This time is used to measure blood flow rate. The difference between the upstream and downstream measured transit times calculates the volume flow.

See also Echo Ranging.