Analyzing an acoustic wave that has propagated through a body of water while the body of water is being frozen

1. A method comprising:

detecting an acoustic wave that is propagating through a body of water, as said body of water is being frozen on a structure, thus yielding a detected acoustic wave;

extracting, from said detected acoustic wave, (a) a frequency component thereof, (b) a magnitude of said frequency component, (c) a harmonic of said frequency component, and (d) a magnitude of said harmonic; and

removing said body of water from said structure when both of (i) said magnitude of said frequency component exceeds a first threshold value, and (ii) said magnitude of said harmonic exceeds a second threshold value.

2. The method of claim 1 ,

wherein said detected acoustic wave is a time-domain signal, and

wherein said extracting comprises:

transforming said time-domain signal to a frequency-domain signal; and

obtaining said frequency component, said magnitude of said frequency component, said harmonic, and said magnitude of said harmonic, from said frequency-domain signal.

3. A system comprising:

a detector that detects an acoustic wave that is propagating through a body of water, as said body of water is being frozen on a structure, thus yielding a detected acoustic wave; and

a processor that:

extracts, from said detected acoustic wave, (a) a frequency component thereof, (b) a magnitude of said frequency component, (c) a harmonic of said frequency component, and (d) a magnitude of said harmonic; and

issues a signal to remove said body of water from said structure when both of (i) said magnitude of said frequency component exceeds a first threshold value, and (ii) said magnitude of said harmonic exceeds a second threshold value.

4. The system of claim 3 ,

wherein said detected acoustic wave is a time-domain signal, and

wherein said processor, to extract said frequency component and said magnitude:

transforms said time-domain signal to a frequency-domain signal; and

obtains said frequency component, said magnitude of said frequency component, said harmonic, and said magnitude of said harmonic, from said frequency-domain signal.

5. The system of claim 3 , wherein said detector comprises a microphone in a probe that is situated less than 0.5 inches from said structure.

6. The system of claim 3 , wherein said detector comprises a microphone in a probe that is in contact with said structure.

7. The system of claim 3 , wherein said detector comprises a microphone in a probe that is situated less than 0.5 inches from said body of water.

8. The system of claim 3 , wherein said detector comprises a microphone in a probe that is in contact with said body of water.

9. A non-transitory computer-readable storage medium comprising instructions that are readable by a processor, and that when read by said processor cause said processor to:

extract, from a detected acoustic wave, (a) a frequency component thereof, (b) a magnitude of said frequency component, wherein said detected acoustic wave represents an acoustic wave that is propagating through a body of water, as said body of water is being frozen on a structure, (c) a harmonic of said frequency component, and (d) a magnitude of said harmonic; and

issue a signal to remove said body of water from said structure when both of (i) said magnitude exceeds a threshold value, and (ii) said magnitude of said harmonic exceeds a second threshold value.

10. The non-transitory computer-readable storage medium of claim 9 , wherein said detected acoustic wave is a time-domain signal, and

wherein said processor, to extract said frequency component and said magnitude:

transforms said time-domain signal to a frequency-domain signal; and

obtains said frequency component, said magnitude of said frequency component, said harmonic, and said magnitude of said harmonic, from said frequency-domain signal.