Importance

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Abstract

An ulrasonic liquid level measurement device is used to measure the depth of a flowing liquid in a channel using an ultrasonic transducer that is positioned out of contact with the liquid and above and directed toward the channel. An ultrasonic burst is directed toward the channel and the reflected echo from the surface of the liquid is returned and sensed by the transducer. The transit time of ultrasonic transmission and echo return is indicative of the liquid level. An adjustable discriminator is provided to specify a maximum liquid level in the channel and a minimum liquid level, which, typically is the floor of the channel. The maximum and minimum levels are adjustable to accomodate variable channel configurations and transducer mounting arrangements. Automatic adjustment is provided to compensate for different cable lengths which may be used to connect the ultrasonic transducer to the transducer driver and receiving section. Temperature compensation is provided to compensate for changes in ultrasonic transmission propogation through ambient air with temperature, and time variable gain amplification is provided to compensate for geometric spreading of reflected ultrasonic energy echo pulses and for air path absorption.

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First Claim