The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 28, 1989
Filed:
Dec. 08, 1986
Dieter Drefahl, Hanau, DE;
Honeywell Regelsysteme GmbH, , DE;
Abstract
A method for operating a transmitting/receiving circuit for ultrasonic signals includes the steps of producing a carrier frequency by a voltage-controlled oscillator having an output frequency controlled in accordance with a temperature dependency of an inherent frequency of the transducer, modulating the carrier frequency, applying the modulated carrier frequency in a transmitting mode to energize an ultrasonic transducer to produce ultrasonic transmission signals, switching from the transmitting mode to a receiving mode, applying output signals from the transducer representative of received ultrasonic signals to a phase-locked-loop circuit using the voltage-controlled oscillator whereby the phase-lock-loop circuit is automatically matched to a frequency of the received signals. An apparatus utilizing this method includes a transmitting/receiving transducer, a phase-locked-loop having a voltage-controlled oscillator, a modulator for applying a modulated carrier frequency to the transducer in a transmitting mode, a transmitting circuit for selectively applying an output from the oscillator as a carrier frequency to the modulator to produce the modulated carrier frequency, a receiving circuit for selectively applying an output from the transducer in a receiving mode for receiving reflected signals to an input of the phase-locked-loop and a temperature responsive element arranged to control the voltage-controlled oscillator at a frequency matched to an inherent frequency of the transducer.