Recent Patents in Signal Processing (November 2015) – Source localization

For our November 2015 issue, we cover recent patents granted in the area of source localization. The section below covers patents granted recently for various signal source localization, including audio source localization algorithms, and novel hardware configurations for source localization such as multiple microphone arrays, tight-pitched detector arrays and wireless communication systems.

In patent no. 9,084,036, a method for performing signal source localization is provided. The method comprises the steps of obtaining compressive measurements of an acoustic signal or other type of signal from respective ones of a plurality of sensors, processing the compressive measurements to determine time delays between arrivals of the signal at different ones of the sensors, and determining a location of a source of the signal based on differences between the time delays. The method may be implemented in a processing device that is configured to communicate with the plurality of sensors. In an illustrative embodiment, the compressive measurements are obtained from respective ones of only a designated subset of the sensors, and a non-compressive measurement is obtained from at least a given one of the sensors not in the designated subset, with the time delays between the arrivals of the signal at different ones of the sensors being determined based on the compressive measurements and the non-compressive measurement.

In the invention no. 9,069,065 techniques are described for determining locations of audio sources. Audio signals are captured from multiple locations. Pairs of the audio signals are analyzed to create correlograms, indicating correlation scores corresponding to different time offsets between the signals. Based on the correlograms, various locations are analyzed to determine probabilities of audio originating from those locations. The highest probabilities are found, indicating locations containing audio sources. In some situations, the audio sources may be reflective sources, and the locations of the reflective sources may be used to determine locations of objects or surfaces.

A sound source localization apparatus is introduced in patent no 9,055,356 for localizing a sound source using an eigenvector, includes, a sound signal input unit inputting a sound signal, a correlation matrix calculation unit calculating a correlation matrix of the input sound signal, and an eigenvector calculation unit calculating an eigenvalue of the correlation matrix using the calculated correlation matrix, wherein the eigenvector calculation unit calculates the eigenvector using the correlation matrix of the input sound signal and one or more predetermined correlation matrices.

As described in patent no. 9,025,415, an audio source localization apparatus receives signals from a microphone array (101), and a reference processor (105) generates at least three reference beams with different directional properties. An estimation processor (107) which generates simultaneous direction estimates for two sound sources, comprises a circuit (401) combining signals of the at least three reference beams with a beam shape parameter reflecting a shape of an audio beamform and a beam direction parameter reflecting a direction of an audio beamform for the combined signal. A cost processor (403) generates a cost measure indicative of an energy of the combined signal and a minimization processor (405) estimates values of the beam shape parameter and the beam direction parameter which correspond to a local minimum of the cost measure. A direction processor (407) then determines simultaneous direction estimates for two sound sources from the determined parameter values. Improved direction estimation for two simultaneous sound sources may be achieved.

In the invention no 8,983,089, an augmented reality environment allows interaction between virtual and real objects. Multiple microphone arrays of different physical sizes are used to acquire signals for spatial tracking of one or more sound sources within the environment. A first array with a larger size may be used to track an object beyond a threshold distance, while a second array having a size smaller than the first may be used to track the object up to the threshold distance. By selecting different sized arrays, accuracy of the spatial location is improved.

Patent no. 8,930,165 introduces a system and method for determining a probability of the location of an illicit radiation source within an environment based on directional detectors. An embodiment includes a plurality of directional radiation detectors distributed about the environment and integrated with a processing unit adapted to determine the probability of the source location based on the radiation count data received from the plurality of detectors. The processing unit is further adapted to output information indicative of the location of the radiation source within the environment.

In the invention no. 8,842,869 a method and apparatus for sound source localization using microphones are disclosed. The method includes: receiving signals coming from a sound source through microphones covering all directions; distinguishing the received signals into those signals directly input to the microphones from the sound source (direct signals) and those signals indirectly input to the microphones (indirect signals); identifying a candidate region at which the sound source is present using locations of the microphones receiving direct signals; selecting a point in the candidate region as a candidate location; drawing one or more virtual tangent lines, contacting with the circumference of the apparatus, from the candidate location; placing locations of the microphones receiving indirect signals on the virtual tangent lines; and localizing the sound source on the basis of signals passing through the microphones receiving direct signals and through the virtual locations of the microphones receiving indirect signals.

In patent no. 8,842,851 systems and methods are described that perform audio source localization in a manner that provides increased robustness and responsiveness in the presence of acoustic echo. The systems and methods calculate a difference between a signal level associated with one or more of the audio signals generated by a microphone array and an estimated level of acoustic echo associated with one or more of the audio signals. This information is then used to determine whether and/or how to perform audio source localization. For example, a controller may use the difference to determine whether or not to freeze an audio source localization module that operates on the audio signals. As another example, the audio source localization module may incorporate the difference (or the estimated level of acoustic echo used to calculate the difference) into the logic that is used to determine the location of a desired audio source.

Systems and methods for performing sound source localization are provided by patent no. 8,553,904. In one aspect, a method for locating a sound source using a computing device subdivides a space into subregions. The method then computes a sound source power for each of subregions and determines which of the sound source energies is the largest. When the volume of the subregion is less than a threshold volume, the method outputs the subregion having the largest sound source power. Otherwise, the stages of partitioning, computing, and determining the subregion having the largest sound source power is repeated.

As show in patent no. 8,494,189, in a virtual sound source localization apparatus, a distance between two loudspeakers and a shortest distance between a line connecting the loudspeakers and a listening position are set beforehand, and a listener operates an operating section to localize a Cch sound source at an approximately center of the loudspeakers, thereby adjusting a sound balance of the loudspeakers. In addition, a controller calculates a difference in distance from the loudspeakers to the listening position, sets a delay amount of delay correctors such that sound emitted from the loudspeakers substantially reaches the listening position simultaneously, and adjusts sound output timing of the loudspeakers. In this way, even though the listening position is changed, the listener can operate the operating section to optimize a virtual surround effect.

Computer-implemented systems and methods are provided in patent no. 8,274,429 for source-localization and self-calibration for an array of antenna elements. In one implementation, a method is provided that includes estimating directions of arrival of a plurality of signals received by a plurality of antenna elements of the array of antenna elements and identifying a target signal from among the plurality of received signals. The method may also include estimating complex gain of each of the plurality of antenna elements in a direction of arrival of the identified target signal, wherein the estimation of the complex gain of each the plurality of antenna elements is performed after estimating the directions of arrival of signals received by the plurality of antenna elements.

If you have an interesting patent to share when we next feature patents related to source localization, or if you are especially interested in a signal processing research field that you would like to highlight in this section, please send email to Csaba Benedek (benedek.csaba AT sztaki DOT mta DOT hu).

References

Number: 9,084,036
Title:   Signal source localization using compressive measurements
Inventors: Jiang; Hong, Mathews; Boyd T., Wilford; Paul A.
Issued: July 14, 2015
Assignee:Alcatel Lucent (Boulogne-Billancourt, FR)

Number: 9,069,065
Title: Audio source localization
Inventors: Coley; Christopher D, Sadek; Ramy S., Pollack; Joshua, Adams; Jeffrey P.
Issued: June 30, 2015
Assignee: Rawles LLC (Wilmington, DE)

Number: 9,055,356
Title: Sound source localization apparatus and sound source localization method
Inventors:Nakadai; Kazuhiro, Nakajima; Hirofumi, Nakamura; Keisuke
Issued: June 9, 2015
Assignee: Honda Motor Co., Ltd. (Tokyo, JP)

Number: 9,025,415
Title: Audio source localization  
Inventors: Derkx; Rene Martinus Maria
Issued: May 5, 2015
Assignee: Koninklijke Philips N.V. (Eindhoven, NL)

Number: 8,983,089
Title: Sound source localization using multiple microphone arrays
Inventors: Chu; Wai C., Crump; Edward Dietz
Issued: March 17, 2015
Assignee: Rawles LLC (Wilmington, DE)

Number: 8,930,165
Title: Source localization using multiple units of a tight-pitched detector array  
Inventors: Vilim; Richard B., Klann; Raymond T.
Issued: January 6, 2015
Assignee: UChicago Argonne, LLC (Chicago, IL)

Number: 8,842,869
Title:   Method and apparatus for sound source localization using microphones
Inventors: Kim; Hyun Soo
Issued: September 23, 2014
Assignee:  Samsung Electronics Co., Ltd.

Number: 8,842,851
Title: Audio source localization system and method  
Inventors: Beaucoup; Franck (Vancouver, CA)
Issued: September 23, 2014
Assignee: Broadcom Corporation (Irvine, CA)

Number: 8,553,904
Title: Systems and methods for performing sound source localization
Inventors: Said; Amir, Lee; Bowon, Kalker; Ton
Issued: October 8, 2013
Assignee: Hewlett-Packard Development Company, L.P. (Houston, TX)

Number: 8,494,189
Title: Virtual sound source localization apparatus
Inventors: Katayama; Masaki
Issued: July 23, 2013
Assignee: Yamaha Corporation (Hamamatsu-shi, JP)

Number: 8,274,429
Title: Wireless communication systems and methods with source localization and self-calibration
Inventors: Zoubir; Ahmed (Ramonville Saint Agne, FR)
Issued: September 25, 2012