Sonic ranging systems to eliminate errors due to variations in the sound velocity in the medium
System and method for determining fluid level in a container
Measurement of distance using ultrasonic signals
Ultrasonic test method and apparatus with coupling liquid temperature compensation
Method and apparatus for determining physical quantities
Medical fluid measuring system
AbstractAn ultrasonic apparatus for measuring the speed of sound in a gaseous medium comprises a chamber in which an ultrasonic transducer is mounted at one end of the chamber and first and second ultrasonic reflecting surface are mounted at the opposite end of the chamber with a temperature insensitive mounting member for mounting the second ultrasonic reflecting surface at a predetermined distance closer to the ultrasonic transducer than the first ultrasonic reflecting surface and a circuit connected to the transducer for converting ultrasonic energy reflections from the first and second reflecting surfaces to a signal corresponding to the speed of the ultrasonic energy between the two ultrasonic reflecting surfaces. Thus, the distance from the transducer to the targets is not relevent - only the distance between the two reflectors which is established by the temperature insensitive mounting member is relevant. In a preferred embodiment, the ultrasonic reflecting surfaces are concentric and coaxial and, the chamber includes a cylindrical cylinder which has a diameter larger than the most remote of the two reflecting surfaces and an annular groove is formed beyond the second reflecting surface.