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Ultrasonic acoustic pulse echo ranging system

  • US 3,985,030 A
  • Filed: 10/29/1974
  • Issued: 10/12/1976
  • Est. Priority Date: 10/29/1974
  • Status: Expired due to Term
First Claim
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1. An ultrasonic acoustic pulse echo ranging system for monitoring the depth of liquid above a datum level in a tank, the system comprising a transmitter transducer and a receiver transducer for mounting side-by-side, upwardly directed and exposed to the liquid in the tank at the datum level, and, for coupling to the transducers from outside the tank, a transmitter including an oscillator to energise the transmitter transducer to transmit acoustic pulses of ultrasonic frequency, a gate to start the oscillator, and a regulator to stop the oscillator to determine the length of each pulse in terms of the number of cycles of the ultrasonic frequency in the pulse, a receiver to detect inputs from the receiver transducer and generate output pulses in response to echoes of the acoustic pulses from the free surface of the liquid, a clock-oscillator-driven continuously cycling digital counter to actuate said gate to start an acoustic pulse at the start of each counting cycle, a several-figure digital display device, and latching means responsive to a receiver output pulse to connect the digital counter to the display device to display a function of the time interval between the transmission of an acoustic pulse and the detection of its echo, said regulator including a regulating counter of the ultrasonic cycles which is re-settable at zero by the stopping of the oscillator, a count comparator having an input from said display device and an input from said regulating counter, and a bi-stable element to provide a first path from the regulating counter to the oscillator and an alterative second path from the count comparator to the oscillator, the regulating counter being adjustable to preselect a maximum length of transmitted acoustic pulse, and the count comparator co-relating said display and the count by the regulating counter to provide that when the display derived from the transmission of an acoustic pulse and the detection of its echo is a function of a time interval greater than a predetermined value the oscillator will be stopped through said first path to terminate the next transmitted pulse at said maximum length, and that when said display so derived is a function of the time interval being less than said predetermined value the oscillator will be stopped through said second path to terminate the next transmitted pulse at a length proportionately less than said maximum length.

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