Multichannel minimum distance chirp echo detection
One implementation of a sensing method includes: correlating a receive signal with a waveform template to obtain a correlation signal in which echoes would be represented as peaks; and varying the waveform template based on time elapsed from a measurement start time.
1. An integrated circuit controller for a sensor, the integrated circuit controller comprising:
a transmitter to drive a piezoelectric transducer to generate acoustic bursts;
a receiver to obtain a receive signal from the piezoelectric transducer after each acoustic burst is generated; and
a processing circuit coupled to the transmitter and to the receiver, the processing circuit configured to apply echo-detection processing to said receive signal, said echo-detection processing including:
correlating a receive signal with a waveform template to obtain a correlation signal in which echoes would be represented as peaks; and
varying the waveform template based on time elapsed from a measurement start time.
2. The integrated circuit controller of claim 1 , wherein the echo-detection processing further comprises scaling the correlation signal based on time elapsed from the measurement start time.
3. The integrated circuit controller of claim 2 , wherein the echo-detection processing further comprises, after said scaling, determining a time of flight associated with any detected peak in the correlation signal.
4. The integrated circuit controller of claim 1 , wherein varying the waveform template includes decreasing a bandwidth of the waveform template based on time elapsed from the measurement start time.
5. The integrated circuit controller of claim 4 , wherein the echo-detection processing further comprises scaling the correlation signal to compensate for a piezoelectric transducer response to a tail of the acoustic burst received after transducer reverberation ends.
6. The integrated circuit controller of claim 4 , wherein the waveform template represents an up-chirp.
7. The integrated circuit controller of claim 4 , wherein the waveform template represents a down-chirp.
8. A method that comprises:
correlating a receive signal with a waveform template to obtain a correlation signal in which echoes would be represented as peaks; and
varying the waveform template based on time elapsed from a measurement start time.
9. The method of claim 8 , further comprising: determining a time of flight associated with any detected peak in the correlation signal.
10. The method of claim 9 , further comprising, before said determining, scaling the correlation signal based on time elapsed from the measurement start time.
11. The method of claim 8 , wherein varying the waveform template includes varying a bandwidth of the waveform template from wide to narrow.
12. The method of claim 11 , further comprising, before determining a time of flight associated with any detected peak in the correlation signal, scaling the correlation signal to compensate for a transducer response to a portion of an acoustic burst received after transducer reverberation ends.
13. The method of claim 11 , wherein the waveform template represents an up-chirp.
14. The method of claim 11 , wherein the waveform template represents a down-chirp.
15. The method of claim 8 , wherein the measurement start time is a debounce interval after a detected end of reverberation.
16. The method of claim 8 , further comprising downconverting the receive signal to zero intermediate frequency (ZIF) before said correlating with the waveform template.
17. An acoustic sensor comprising:
a piezoelectric transducer; and
an integrated circuit controller that includes:
a transmitter to drive the piezoelectric transducer to generate acoustic bursts;
a receiver to obtain a receive signal from the piezoelectric transducer after each acoustic burst is generated; and
a processing circuit coupled to the transmitter and to the receiver, the processing circuit configured to apply echo-detection processing to said receive signal, said echo-detection processing including:
correlating a receive signal with a waveform template to obtain a correlation signal in which echoes would be represented as peaks; and
varying the waveform template based on time elapsed from a measurement start time.
18. The acoustic sensor of claim 17 , wherein varying the waveform template includes decreasing a bandwidth of the waveform template based on time elapsed from the measurement start time.
19. The acoustic sensor of claim 18 , wherein the echo-detection processing further comprises scaling the correlation signal to compensate for a piezoelectric transducer response to a tail of the acoustic burst received after transducer reverberation ends.