Sensing characteristics and a type of fluid using a temperature dependent rate of change of a measurement of the fluid

1. A method of sensing a fluid, the method comprising:

transmitting, via a transducer, a first ultrasonic pulse through a portion of the fluid toward a reflector;

receiving, via the transducer, a first echo of the first ultrasonic pulse, wherein the first ultrasonic pulse is transmitted and the first echo is received within a first time period;

determining a first measurement of the first ultrasonic pulse;

determining, via a temperature sensor, a first temperature, the first temperature determined at the first time period;

transmitting, via the transducer, a second ultrasonic pulse through the portion of the fluid toward the reflector;

receiving, via the transducer, a second echo of the first ultrasonic pulse, wherein the second ultrasonic pulse is transmitted and the second echo is received within a second time period;

determining a second measurement of the second ultrasonic pulse;

determining, via the temperature sensor, a second temperature, the second temperature determined at the second time period;

determining, via a controller, a slope based on the first measurement, the second measurement, the first temperature, and the second temperature; and

comparing, via the controller, at least one selected from the group consisting of the slope to a predetermined slope and the first measurement to a predetermined measurement.

2. The method of claim 1 , wherein the first measurement is a first time-of-flight, the second measurement is a second time-of-flight, and the predetermined measurement is a predetermined time-of-flight.

3. The method of claim 1 , wherein the first measurement is a first speed-of-sound, the second measurement is a second speed-of-sound, and the predetermined measurement is a predetermined speed-of-sound.

4. The method of claim 1 , further comprising outputting, from the controller, a signal based on the comparison.

5. The method of claim 4 , wherein the signal is output when the slope deviates from the predetermined slope.

6. The method of claim 5 , wherein the signal is an error signal.

7. The method of claim 1 , further comprising determining, via the controller, a characteristic of the fluid based on the comparison.

8. The method of claim 7 , wherein the characteristic of the fluid is at least one selected from the group consisting of a grade, a brand, a viscosity, and a quality.

9. The method of claim 7 , further comprising outputting, from the controller, a signal based on the characteristic of the fluid.