Importance

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Abstract

A circuit for measuring and indicating the separation distance between a vehicle and adjacent obstacles, consisting of a pulse controlled ultrasonic generator, an ultrasonic transmit-receive transducer connected to the generator for transmitting direct ultrasonic pulse signals to distant obstacles, and receiving these signals that are reflected from the obstacles, an amplifier and detector circuit connected to the transducer output for amplifying the received pulse signals, a first comparator which is connected to the amplifier and and detector stage, and a start-stop counter coupled to the output of the first comparator for measuring the difference in time between the end of the transmitted ultrasonic signal, and the reception of the reflected signal from the obstacle. There is also provided a noise suppression circuit coupled to the output of said first comparator and a second comparator coupled to both the output of the noise suppression circuit and the output of said start-stop counter. The start-stop counter begins its measurement of time used for determining the separation distance between the transducer and distant obstacles by beginning its measurement at the trailing edge of the transmitted pulse appearing in said receiver circuit.

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First Claim