Handsfree system for use in a vehicle
View Patent ↗The invention is directed to a handsfree system for use in a vehicle comprising a microphone array with at least two microphones and a signal processing means wherein the signal processing means comprises the superdirective beamformer with fixed superdirective filters.
1. A system for use in a vehicle comprising:
a microphone array with at least two microphones; and
a superdirective beamformer with fixed superdirective filters;
where the superdirective beamformer is a regularized superdirective beamformer using a finite regularization parameter μ that is frequency dependent.
2. A system according to claim 1 where each superdirective filter results from an iterative design based on a predetermined maximum susceptibility.
3. A system according to claim 1 where each superdirective filter comprises a filter in the time domain.
4. A system according to claim 1 where the signal processing means further comprises at least one inverse filter for adjusting a microphone transfer function.
5. A system according to claim 4 where the at least one inverse filter comprises a warped inverse filter.
6. A system according to claim 4 where each inverse filter comprises an approximate inverse of a non-minimum phase filter.
7. A system according to claim 4 where each inverse filter is combined with a superdirective filter of the beamformer.
8. A system according to claim 1 where the beamformer comprises the structure of a generalized sidelobe canceller (GSC).
9. A system according to claim 1 where the beamformer comprises a minimum variance distortionless response (MVDR) beamformer.
10. A system according to claim 1 where the microphone array comprises at least two microphones arranged in an endfire orientation with respect to a first position.
11. A system according to claim 10 where the microphone array comprises at least two microphones arranged in endfire orientation with respect to a second position.
12. A system according to claim 11 where the at least two microphones in the first endfire orientation and the at least two microphones in the second endfire orientation comprise a microphone in common.
13. A system according to claim 1 where the microphone array comprises at least two subarrays.
14. A system according to claim 13 where the at least two subarrays comprise at least one microphone in common.
15. A system according to claim 1 further comprising a frame where each microphone of the microphone array is arranged in a predetermined position in or on the frame.
16. A system according to claim 15 where the predetermined position comprises a fixed position in or on the frame.
17. A system according to claim 1 where at least one microphone comprises a directional microphone.
18. A system according to claim 17 where the directional microphone comprises a directional microphone with a cardioid characteristic.
19. A system according to claim 17 where the directional microphone comprises a differential microphone.
20. A system according to claim 1 comprising a vehicle coupled to the microphone and the beamformer.
21. A system for use in a vehicle comprising:
a microphone array with at least two microphones and a superdirective beamformer having fixed superdirective filters;
where the superdirective beamformers are configured with a predetermined susceptibility that is based on a relative error of the microphone array;
where the relative error of the microphone array is a sum of mean square error of transfer properties of each microphone in the microphone array and a gaussian error with zero mean of microphone positions.
22. A system according to claim 21 where at least two microphones in the microphone array are arranged in an endfire orientation with respect to a first position.
23. A system according to claim 22 where at least two microphones in the microphone array are arranged in an endfire orientation with respect to a second position.
24. A system according to claim 21 where at least one microphone comprises a directional microphone.
25. A system according to claim 24 where the directional microphone comprises a directional microphone with a cardio characteristic.
26. A system according to claim 24 where the directional microphone comprises a differential microphone.