Fluid level sensing utilizing ring-time signatures of a transducer

1. A level measurement system comprising:

a tank configured to contain a liquid having a surface level;

a transducer positioned at a predetermined position on a first sidewall of the tank, the transducer configured to output an ultrasonic signal into toward a second sidewall of the tank; and

a controller having a memory and electronic processor, the controller electrically coupled to the transducer, the controller configured to

determine a ring time of the transducer,

determine, based on the ring time of the transducer, when the transducer is in an air-coupled state,

determine the surface level of the fluid to be below the predetermined position when the transducer is in the air-coupled state,

determine, based on the ring time of the transducer, when the transducer is in a liquid-coupled state, and

determine the surface level of the fluid to be above the predetermined position when the transducer is in the liquid-coupled state.

2. The level measurement system of claim 1 , wherein the transducer is in the liquid-coupled state the ring time is below a ring time threshold.

3. The level measurement system of claim 1 , wherein the transducer is in the air-coupled state when the ring time is above a ring time threshold.

4. The level measurement system of claim 1 , wherein the controller is further configured to determine a ring time threshold.

5. The level measurement system of claim 4 , wherein the ring time threshold is based on a temperature of the liquid contained within the tank.

6. The level measurement system of claim 1 , wherein the controller is further configured to output the surface level of the liquid contained within the tank.

7. The level measurement system of claim 1 , wherein transducer has a first ring time when in the liquid-coupled state and a second ring time when in the air-coupled state.

8. The level measurement system of claim 7 , wherein the second ring time is approximately double the first ring time.

9. A method of determining a level of a fluid in a tank, the method comprising:

providing a transducer at a predetermined position on a sidewall of the tank;

activating, via a controller, the transducer;

determining a ring time of the transducer;

determining, based on the ring time of the transducer, whether the transducer is in an air-coupled state or a liquid-coupled state;

determining the level of the fluid to be below the predetermined position when the transducer is in the air-coupled state;

determining the level of the fluid to be above the predetermined position when the transducer is in the liquid-coupled state, and

outputting, via the controller, the level of the fluid in the tank.

10. The level measurement system of claim 9 , wherein the transducer is liquid coupled when the ring time is below a ring time threshold.

11. The level measurement system of claim 9 , wherein the transducer is air coupled when the ring time is above a ring time threshold.

12. The level measurement system of claim 9 , wherein the controller is further configured to determine a ring time threshold.

13. The level measurement system of claim 12 , wherein the ring time threshold is based on the temperature of the fluid within the tank.

14. The level measurement system of claim 9 , wherein the controller is further configured to output the level of the liquid contained within the tank.

15. The level measurement system of claim 9 , wherein transducer has a first ring time when liquid coupled and a second ring time when air coupled.

16. The level measurement system of claim 15 , wherein the second ring time is approximately double the first ring time.