Apparatus and method for measuring liquid level in a well

An apparatus for measuring the distance between a reference point and a target surface, the apparatus comprising:

• a signal generator that is configured to generate a signal and transmit the signal through a medium towards the target surface, the target surface comprising a substance that will reflect the signal;
• a detector that is configured to detect signals;
• a processing unit that is communicatively coupled to the detector and configured to:
• receive a calibration signal, wherein the calibration signal is an output of the detector generated by the detection of a reflection of the generated signal resulting from the generated signal striking a calibrated-constrictive element that is located at a known position relative to the reference point;
• receiving a measurement signal, wherein the measurement signal is an output of the detector generated by the detection of a reflection of the generated signal resulting from the generated signal striking the target surface;
• determine the propagation speed of the calibration signal;
• and
• generating a measurement of the distance between the reference point and the target surface based on the time the measurement signal was received and the determined propagation speed;
• can output interface for provided the generated distance measurement.

A method for making a measurement of the distance between a known point and target surface of a substance in a void, the method comprising the acts of:

• generating an acoustic signal at a known position relative to a reference point;
• injecting the acoustic signal into a proximate end of the void toward the distal end;
• receiving a calibration signal, wherein the calibration signal is a reflection of the acoustic signal resulting from the acoustic signal striking a calibrated-constrictive element that is located at a known position relative to the reference point;
• receiving a measurement signal, wherein the measurement signal is a reflection of the acoustic signal resulting from the acoustic signal striking the target surface;
• determining the propagation speed of the calibration signal;
• and
• generating a measurement of the distance between the reference point and the target surface based on the time the measurement signal was received and the determined propagation speed.