Abstract: An ultrasonic fluid vibrating type flowmeter comprising a set of ultrasonic transmitter and ultrasonic receiver mounted on a pipe carrying the fluid whose flow rate is to be measured; driving device for intermittently driving the transmitter using burst waves containing an oscillation frequency to cause the transmitter to apply ultrasonic signals to the fluid and cause its vibration; standard timing device for generating a standard signal to control the timing of the burst waves whereby the receiver receives an amplitude modulated signal whose amplitude is modulated by the frequency modulation caused by vibration of the fluid; and sampling device for sampling an envelope of the amplitude modulated signal in synchronism with the standard signal and at times governed by a predetermined function, whereby the vibration frequency of the fluid is detected from the sampled amplitude modulated envelope while concurrently removing noise influences.

Abstract: A vortex flowmeter comprising a signal converting sensor for converting a flow rate to be measured into a vortex signal, a tracking filter section in a subsequent stage, and a noise discriminating circuit. The tracking filter section receives the output amplitude of the signal converting sensor, changes the corner frequency of a low pass filter, and delivers a filtered signal. The noise discriminating circuit receives a frequency signal obtained by frequency conversion of the filtered signal and the output amplitude of the signal converting sensor, performs a given calculation to achieve noise discrimination, and prevents output of the frequency signal when noise is found.

Abstract: A transmitter- receiver of an ultrasonic distance measuring device comprising a cylindrical piezoelectric element made of a polymer in place of a piezoelectric vibrator of a ceramic material or the like which has heretofore been used. The cylindrical piezoelectric element is secured to a columnar supporter in such a manner as to define a chamber in cooperation with a recess which is provided in the peripheral surface of the supporter. The supporter is provided with a pressure equalizing bore which provides communication between the chamber and the outside. In addition, a conical reflector is provided so as to impart directivity to the ultasonic wave transmitted from the piezoelectric element.