US 12,342,136 B2
Signal processing methods and system for beam forming with improved signal to noise ratio
Dietmar Ruwisch, Berlin (DE)
Assigned to Analog Devices International Unlimited Company, Limerick (IE)
Filed by Analog Devices International Unlimited Company, Limerick (IE)
Filed on Jan. 7, 2022, as Appl. No. 17/571,361.
Application 17/571,361 is a continuation of application No. PCT/EP2020/069599, filed on Jul. 10, 2020.
Claims priority of application No. 19185502 (EP), filed on Jul. 10, 2019.
Prior Publication US 2022/0132241 A1, Apr. 28, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. H04R 3/00 (2006.01); H04R 1/40 (2006.01); G10L 21/0216 (2013.01); G10L 21/0232 (2013.01)
CPC H04R 3/005 (2013.01) [H04R 1/406 (2013.01); G10L 2021/02166 (2013.01); G10L 21/0232 (2013.01); H04R 2410/01 (2013.01); H04R 2410/07 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method of generating a directional output signal from sound received by at least two microphones, said method comprising:
transforming analog-to-digital converted time-domain signals provided by respective ones of said at least two microphones into corresponding complex-valued frequency-domain microphone signals, with the at least two microphones closely spaced apart from one another and arranged as a microphone array within a vehicle, the analog-to-digital converted time-domain signals representing respective sounds received by the at least two microphones, wherein each one of the corresponding complex-valued frequency-domain microphone signals has a frequency component value for each frequency component of a plurality of frequency components;
calculating from the corresponding complex-valued frequency-domain microphone signals, for a Beam Focus Direction, a Beam Focus Spectrum by means of a Characteristic Function that controls a shape of the Beam Focus Direction and depends on frequency by means of a frequency-dependent exponent, said Beam Focus Spectrum comprises, for each frequency component of the plurality of frequency components, a time-dependent, real-valued attenuation factor, with the Beam Focus Direction pointing to a position of an occupant of the vehicle;
multiplying, for each frequency component of the plurality of frequency components, the time-dependent, real-valued attenuation factor with the frequency component value of a complex-valued frequency-domain microphone signal of one of said at least two microphones to obtain a directional frequency component value;
forming a frequency-domain directional output signal from directional frequency component values for each of the plurality of frequency components;
synthesizing, from the frequency-domain direction output signal, by means of inverse transformation, a time-domain directional output signal, with time-domain directional output signal having the Beam Focus Direction; and
causing output, via a loudspeaker, of the time-domain directional output signal.