Handsfree communication system
View Patent ↗A handsfree communication system includes microphones, a beamformer, and filters. The microphones are spaced apart and are capable of receiving acoustic signals. The beamformer compensates for propagation delays between the direct and reflected acoustic signals. The filters are configured to a predetermined susceptibility level. The filter process the output of the beamformer to enhance the quality of the received signals.
1. A method to design a superdirective beamformer filter in the frequency domain based on a predetermined susceptibility, comprising:
calculating a filter transfer function based on a regularization parameter;
calculating a susceptibility based on the determined transfer function;
determining if the calculated susceptibility exceeds the predetermined susceptibility;
changing the value of the regularization parameter and re-calculating the filter transfer function and the susceptibility until the susceptibility is within an acceptable range of the predetermined susceptibility; and
configuring the superdirective beamformer filter according to the calculated transfer function.
2. The method of claim 1 , where the act of calculating a filter transfer function based on the regularization parameter comprises determining A i (ω) where
A
i
(
ω
)
=
(
Γ
(
ω
)
+
μ
I
)
-
1
d
d
T
(
Γ
(
ω
)
+
μ
I
)
-
1
d
.
3. The method of claim 2 , where the act of calculating the susceptibility comprises determining K(ω) where
K
(
ω
)
=
1
WNG
(
ω
)
=
A
(
ω
)
H
A
(
ω
)
A
(
ω
)
H
d
(
ω
)
.
4. The method of claim 1 , where the act of changing the value of the regularization parameter comprises increasing the value of the regularization parameter when the calculated susceptibility exceeds the predetermined susceptibility.
5. The method of claim 1 , where the act of changing the value of the regularization parameter comprises decreasing the value of the regularization parameter when the calculated susceptibility is less than the regularization parameter.