Audio Localization Using Audio Signal Encoding and Recognition

• US 20120214544A1
• Filed: 02/23/2011
• Published: 08/23/2012
• Est. Priority Date: 02/23/2011
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rodriguez, Tony F., Shivappa, Shankar Thagadur
• Granted Patent: US 9,270,807 B2
• Time in Patent Office: Days
• US Class Current: 455/556.1
• CPC Class Codes: G06Q 30/02 Marketing; Price estimation or determination; Fundraising
• CPC Class Codes: G06Q 30/0261 based on user location
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: H04M 1/72457 according to geographic location
• CPC Class Codes: H04R 29/007 for public address systems public address systems per se H04R27/00
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A positioning network comprises an array of signal sources that transmit signals with unique characteristics that are detectable in signals captured through a sensor on a mobile device, such as a microphone of a mobile phone handset. Through signal processing of the captured signal, the positioning system distinguishes these characteristics to identify distinct sources and their corresponding coordinates. A position calculator takes these coordinates together with other attributes derived from the received signals from distinct sources, such as time of arrival or signal strength, to calculate coordinates of the mobile device. A layered protocol is used to introduce distinguishing characteristics in the source signals. This approach enables the use of low cost components to integrate a positioning network on equipment used for other functions, such as audio playback equipment at shopping malls and other venues where location based services are desired.

Claims

1. A method of determining position of a mobile device comprising:

receiving audio signals from two or more different audio sources in a microphone of the mobile device, wherein the audio signals sound substantially similar to a human listener, yet have different characteristics to distinguish among the different audio sources;

distinguishing the audio signals from each other based on two or more layers of distinguishing characteristics determined from the audio signals, wherein a first layer provides information to identify a group of audio sources, and a second layer provides information to identify a particular audio source within the group;

based on identifying particular audio sources, determining location of the particular audio sources;

determining position of the mobile device a based on the locations of the particular audio sources.

2. The method of claim 1 comprising determining position of the mobile device based on the locations of the audio sources and relative attributes of the received audio signals.

3. The method of claim 2 wherein the relative attributes comprise time of arrival of the received audio signals.

4. The method of claim 2 wherein the relative attributes comprise strength of signal metrics derived from analyzing strength of audio signals from different sources.

5. The method of claim 1 wherein the mobile device comprises a mobile telephone.

6. The method of claim 1 wherein distinguishing the audio signals comprises detecting a digital watermark encoded into host audio content.

7. The method of claim 1 wherein distinguishing the audio signals comprises differentiating source by performing a content fingerprint recognition.

8. The method of claim 1 wherein the distinguishing comprises detecting an echo pattern associated with a group of sources or particular audio source.

9. The method of claim 1 wherein the distinguishing comprises detecting a pattern of frequency tones.

10. The method of claim 1 wherein the distinguishing comprises detecting a pattern of alterations introduced into the audio signals prior to output of the audio signals from respective source devices, wherein the alterations are separately detectable, yet the output audio signals are perceived to be the same signal by human listeners.

11. The method of claim 10 wherein the pattern of alterations is inserted by a signal processing circuit in a path from an audio playback system to a speaker.

12. The method of claim 10 wherein the pattern comprises a temporal jitter.

13. A position system comprising:

a microphone for receiving audio source signals in an audible range and converting to an electronic signal, wherein the audio signals sound substantially similar to a human listener, yet have different characteristics to distinguish among the different audio sources; and

one or more processors for accessing the electronic signal corresponding to received audio signals and distinguishing the audio signals from each other based on two or more layers of distinguishing characteristics determined from the audio signals, wherein a first layer provides information to identify a group of audio sources, and a second layer provides information to identify a particular audio source within the group, and for determining location of the particular audio sources based on identifying the particular audio sources and determining position of the mobile device a based on the locations of the particular audio sources.

14. An audio signal generation system comprising:

a controller for controlling an audio signal output by an audio playback device, the audio signal comprising a first layer of characteristics for identifying a group of loudspeakers connected to the audio playback device; and

a signal processor connected between the audio playback device and a first loudspeaker to introduce a second layer of signal characteristics into the audio signal to distinguish the audio signal from the first loudspeaker to which the signal processor is connected; and

a database storing an association between layers of unique characteristics of the audio signals and position of the loudspeakers, the database being responsive to queries to provide position of a loudspeaker corresponding to unique characteristics derived from audio signals from the loudspeakers.

15. The system of claim 14 wherein the signal processor comprises a delay line circuit for introducing a pattern of echoes associated with a particular loudspeaker to which the delay line circuit is connected.

16. The system of claim 14 wherein the signal processor comprises frequency oscillators for introducing a pattern of frequency tones associated with a particular loudspeaker to which the signal process or is connected.

19. The method of claim 16 wherein the relative attribute comprises time of arrival of distinct audio signals.

20. The method of claim 16 wherein the relative attribute comprises strength of signal from distinct audio signal sources.

17. A method of determining position of a mobile device comprising:

receiving source signals from two or more different sources in a sensor of the mobile device;

distinguishing the source signals from each other based on two or more layers of distinguishing characteristics determined from the source signals, wherein a first layer provides information to identify a group of sources, and a second layer provides information to identify a particular source within the group;

based on identifying particular sources, determining location of the particular sources;

determining position of the mobile device a based on the locations of the particular sources and relative attributes of the received source signals.

18. A method of determining position of a mobile device comprising:

receiving audio signals from two or more different audio sources in a microphone of the mobile device, wherein the audio signals sound substantially similar to a human listener, yet have different characteristics to distinguish among the different audio sources;

distinguishing the audio signals from each other based on distinguishing characteristics determined from the audio signals, wherein the distinguishing characteristics provides information to identify a particular audio source;

based on identifying particular audio sources, determining location of the particular audio sources;

determining position of the mobile device a based on the locations of the particular audio sources and a relative attribute of the received audio signals.