Composite acoustic bursts for multi-channel sensing

1. An acoustic sensing method that comprises:

driving an acoustic transducer to send composite acoustic bursts each including multiple individual bursts, each individual burst associated with a frequency band, the composite acoustic bursts each having a burst signature that comprises a source-specific arrangement of said frequency bands;

receiving echo signals including self-generated echoes responsive to the composite acoustic bursts from the transducer, and potentially including extra echoes responsive to acoustic bursts from other sources;

categorizing received echo signals by source based on the burst signature; and

using the self-generated echoes exclusive of the extra echoes to determine a distance or time of flight from the transducer.

2. The method of claim 1 , wherein said categorizing includes identifying extra echoes responsive to composite acoustic bursts having a second burst signature associated with a second sensor.

3. The method of claim 2 , further comprising determining, based on the identified extra echoes, a distance or time of flight from the second sensor to the acoustic transducer.

4. The method of claim 1 , wherein at least one frequency band in the burst signature is a center-band of the transducer.

5. The method of claim 4 , wherein at least one frequency band in the burst signature is a lower-band of the transducer.

6. The method of claim 4 , wherein at least one frequency band in the burst signature is an upper-band of the transducer.

7. The method of claim 4 , wherein the composite acoustic burst consists of two individual bursts.

8. The method of claim 7 , wherein a second of the two individual bursts begins before residual reverberation of a first individual burst ceases.

9. The method of claim 7 , wherein the burst signature further comprises a source-specific inter-burst interval.

10. A sensor suitable for use in a sensor array, the sensor comprising:

an acoustic transducer that sends composite acoustic bursts having a burst signature and that receives echo signals, the echo signals including self-generated echoes responsive to the composite acoustic bursts from the transducer, and potentially including extra echoes responsive to acoustic bursts from other sources; and

a controller that categorizes the received echo signals by source based on the burst signature and that determines a distance or time of flight from the transducer using only the self-generated echoes,

wherein the composite acoustic burst comprises multiple individual bursts each having an associated frequency band, and wherein the burst signature comprises a source-specific arrangement of associated frequency bands.

11. The sensor of claim 10 , wherein at least one frequency band in the burst signature is a center band of the transducer.

12. The sensor of claim 11 , wherein at least one frequency band in the burst signature is a lower band of the transducer.

13. The sensor of claim 11 , wherein at least one frequency band in the burst signature is an upper band of the transducer.

14. The sensor of claim 11 , wherein the composite acoustic burst consists of two individual bursts.

15. The sensor of claim 14 , wherein a second of the two individual bursts begins before residual reverberation of a first individual burst ceases.

16. The sensor of claim 14 , wherein the burst signature further comprises an inter-burst interval.

17. The sensor of claim 10 , wherein the controller further employs a second burst signature associated with a second sensor in the array to categorize extra echoes responsive to acoustic bursts from the second sensor.

18. The sensor of claim 17 , wherein the controller further determines a distance or time of flight from the second sensor to the acoustic transducer using only the extra echoes from the second sensor.

19. The sensor of claim 10 , wherein the acoustic transducer is a piezoelectric element.

20. A sensor array comprising:

an electronic control unit;

a first acoustic transducer that sends composite acoustic bursts having a first burst signature, that receives echo signals including self-generated echoes responsive to the composite acoustic bursts from the first transducer; and

a second acoustic transducer that sends composite acoustic bursts having a second burst signature, and that receives echo signals including self-generated echoes responsive to the composite acoustic bursts from the second transducer,

wherein the composite acoustic burst comprises multiple individual bursts each having an associated frequency band,

wherein the first and second burst signatures comprise distinct arrangements of associated frequency bands,

wherein the first and second acoustic transducers each include a center band correlation filter and at least one of an upper band correlation filter and a lower band correlation filter, and

wherein the electronic control unit receives output signals from the correlation filters, categorizes the received echo signals based on the burst signatures, and determines a distance or time of flight from each of the first and second transducers using only their self-generated echoes.

21. The sensor array of claim 20 , wherein the arrangement of associated frequency bands for the first burst signature is an upper band and a center band, and wherein the arrangement for the second burst signature is a lower band and the center band.

22. The sensor array of claim 21 , wherein each composite acoustic burst consists of two individual bursts with no inter-burst space.

23. The sensor array of claim 20 , wherein each of the first and second transducers supplies to the electronic control unit output signals from an upper band correlation filter, a center band correlation filter, and a lower band correlation filter.