Motion-compensated distance sensing with concurrent up-chirp down-chirp waveforms
Various sensors, sensor controllers, and sensing methods are suitable for use in a multi-channel ultrasonic sensor array such as those used in systems for parking assistance, blind spot monitoring, and driver assistance. One illustrative acoustic sensing method includes: driving an acoustic transducer to send acoustic bursts each including an up-chirp in a first frequency band and a down-chirp in a second frequency band; receiving echo signals responsive to the acoustic bursts from the transducer; and using the echo signals to determine a distance or time of flight from the transducer. Another acoustic sensing method includes: driving an acoustic transducer to send acoustic bursts each including a concurrent up-chirp and down-chirp; receiving echo signals responsive to the acoustic bursts from the transducer; and using the echo signals to determine a distance or time of flight from the transducer.
1. An acoustic sensing method that comprises:
driving an acoustic transducer to send acoustic bursts each including an up-chirp in a first frequency band and a down-chirp in a second frequency band;
receiving echo signals responsive to the acoustic bursts from the transducer; and
using the echo signals to determine a distance or time of flight from the transducer.
2. The acoustic sensing method of claim 1 , wherein each of the acoustic bursts includes the up-chirp superimposed with the down-chirp.
3. The acoustic sensing method of claim 1 , wherein the first and second frequency bands are non-overlapping.
4. The acoustic sensing method of claim 1 , wherein the acoustic transducer supports multiple options for at least one of the first and second frequency bands to provide a source-specific signature for the acoustic bursts that enables self-generated echo signals to be distinguished from echo signals concurrently generated from other sources.
5. The acoustic sensing method of claim 4 , wherein the first frequency band is a center band supported by the acoustic transducer, and wherein the second frequency band is an upper band or a lower band supported by the acoustic transducer.
6. The acoustic sensing method of claim 5 , wherein said using includes:
correlating the echo signals with a center band up-chirp and at least one of a lower band down-chirp and an upper band down-chirp;
detecting arrival times associated with up-chirp and down-chirp correlation peaks; and
combining the arrival times to estimate a Doppler shift or relative velocity of a target.
7. The acoustic sensing method of claim 6 , wherein said using further includes adjusting the arrival time associated with the up-chirp based on the Doppler shift or relative velocity of the target.
8. An acoustic sensing method that comprises:
driving an acoustic transducer to send acoustic bursts each including a concurrent up-chirp and down-chirp;
receiving echo signals responsive to the acoustic bursts from the transducer; and
using the echo signals to determine a distance or time of flight from the transducer.
9. The acoustic sensing method of claim 8 , wherein the up-chirp is sent in a first frequency band and the down-chirp is sent in a second frequency band.
10. The acoustic sensing method of claim 8 , wherein said using includes:
correlating the echo signals with an up-chirp and with a down-chirp;
detecting arrival times associated with up-chirp and down-chirp correlation peaks; and
combining the arrival times to estimate a Doppler shift or relative velocity of a target.
11. The acoustic sensing method of claim 10 , wherein said using further includes adjusting the arrival time associated with the up-chirp based on the Doppler shift or relative velocity of the target.
12. A sensor controller comprising:
a transmitter configured to couple to an acoustic transducer to send acoustic bursts each including an up-chirp in a first frequency band and a down-chirp in a second frequency band;
a receiver configured to couple to the acoustic transducer to receive echo signals responsive to the acoustic bursts; and
a processor configured to derive a distance or time of flight from the echo signals.
13. The sensor controller of claim 10 , wherein each of the acoustic bursts includes the up-chirp superimposed with the down-chirp.
14. The sensor controller of claim 10 , wherein the first and second frequency bands are non-overlapping.
15. The sensor controller of claim 10 , wherein the sensor controller is configured to support multiple options for at least one of the first and second frequency bands to provide a sensor-specific signature for the acoustic bursts that enables self-generated echo signals to be distinguished from echo signals concurrently generated from other sensors.
16. The sensor controller of claim 15 , wherein the first frequency band is a center band supported by the acoustic transducer, and wherein the second frequency band is an upper band or a lower band supported by the acoustic transducer, wherein said processor is configured to derive the distance or time of flight by:
correlating the echo signals with a center band up-chirp and at least one of a lower band down-chirp and an upper band down-chirp;
detecting arrival times associated with up-chirp and down-chirp correlation peaks;
combining the arrival times to estimate a Doppler shift or relative velocity of a target; and
adjusting the arrival time associated with the up-chirp based on the Doppler shift or relative velocity of the target.
17. A sensor controller comprising:
a transmitter configured to drive an acoustic transducer to send acoustic bursts each including a concurrent up-chirp and down-chirp;
a receiver configured to couple to the acoustic transducer to receive echo signals responsive to the acoustic bursts; and
a processor configured to operate on the echo signals to determine a distance or time of flight from the transducer.
18. The sensor controller of claim 17 , wherein the up-chirp is sent in a first frequency band and the down-chirp is sent in a second frequency band.
19. The sensor controller of claim 17 , wherein said processor is configured to determine the distance or time of flight by:
correlating the echo signals with an up-chirp and with a down-chirp;
detecting arrival times associated with up-chirp and down-chirp correlation peaks;
combining the arrival times to estimate a Doppler shift or relative velocity of a target; and
adjusting the arrival time associated with the up-chirp based on the Doppler shift or relative velocity of the target.
20. The sensor controller of claim 17 , wherein as part of operating on the echo signals, said processor is configured to derive a Doppler shift estimate from the echo signals.