An oscillating ultrasonic sensor can be built using a pair of ultrasonic transducers and an amplifier but this configuration is insufficient for getting consistent output readings within a single frequency interval. Inclusion of a band pass filter and phase shifter enables frequency interval limiting and setting the desired frequency at the sensor's calibration point. These circuits are implemented using various construction techniques and components and are discussed in the paper along with two relevant block diagrams, one being convenient for research purposes and the other for production. Experimental results obtained for temperature and tilt sensors are presented.

No abstract

We investigated the possibility of linear angle measurement of a vessel using a pair of partially submerged ultrasound transducers mounted on its walls. Measurements of the transfer function at different tilts of the vessel showed noticeable changes both in magnitude and phase responses. These changes were found easiest to track from the output frequency of an oscillator formed by using the transducers in a positive feedback loop. The output frequency depended on the tilt parabolically and its relative scatter was found lower compared to that of the angular output of an industrial accelerometer. The achieved output frequency capture rate of 150 measurements per second enabled meaningful tracking of dynamic changes of the test rig tilt in real time.