Audio localization using multilateration

• US 8,705,320 B1
• Filed: 09/13/2012
• Issued: 04/22/2014
• Est. Priority Date: 09/13/2012
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Holt, Jason, Lyon, Richard Francis
• Primary Examiner(s): Alsomiri, Isam
• Assistant Examiner(s): HULKA, JAMES R
• Application Number:
  US13/615,212
• Time in Patent Office: 586 Days
• Field of Search: 367/124, 367/125, 367/127
• US Class Current: 367/125
• CPC Class Codes: G01S 3/8083 determining direction of source
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: G01S 5/26 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/28 takes precedence

Abstract

Systems and methods for providing audio localization are provided. In some aspects, a method includes receiving phase offsets of a plurality of fixed transmitters from a source other than the plurality of fixed transmitters, detecting an audio localization signal from each of the plurality of fixed transmitters, determining a received phase of the audio localization signal from each of the plurality of fixed transmitters, determining time differences of flight from the mobile receiver to the plurality of fixed transmitters using the received phases, determining distance differences from the mobile receiver to the plurality of fixed transmitters using the time differences of flight, and determining the location of the mobile receiver by performing multilateration using the distance differences.

Claims

1. A machine-implemented method for determining a location of a mobile receiver, the method comprising:

receiving phase offsets of a plurality of fixed transmitters from a source other than the plurality of fixed transmitters;

detecting an audio localization signal from each of the plurality of fixed transmitters;

determining a received phase of the audio localization signal from each of the plurality of fixed transmitters, wherein the received phase is determined by performing fast Fourier transform on a pseudorandom sequence;

determining time differences of flight from the mobile receiver to the plurality of fixed transmitters using the received phases and phase offsets of the fixed transmitters;

determining distance differences from the mobile receiver to the plurality of fixed transmitters using the time differences of flight; and

determining the location of the mobile receiver by performing multilateration using the distance differences.

2. The method of claim 1, wherein the phase offsets are received from a fixed receiver via a data channel.

3. The method of claim 2, wherein the data channel is a radio channel.

4. The method of claim 2, wherein the data channel is a Wifi channel or a 3G channel.

5. The method of claim 1, wherein the audio localization signal comprises a pseudorandom sequence.

6. The method of claim 1, wherein the received phase is determined by performing convolution on a pseudorandom sequence.

7. The method of claim 1, wherein the determining of the distance differences further comprises:

multiplying the time differences of flight with the speed of sound.

8. A mobile receiver in a wireless positioning system, comprising:

a receiver for receiving phase offsets of a plurality of fixed transmitters;

a microphone for detecting an audio localization signal from each of the plurality of fixed transmitters; and

a localization module comprising;

a phase detector for determining a received phase of the audio localization signal of the respective fixed transmitter, the phase detector comprising a convolution unit for determining the received phase by performing convolution on the pseudorandom sequence, wherein the convolution unit determines the received phase by performing Delay Locked Loops on the pseudorandom sequence;

a time difference of flight calculator for determining time differences of flight from the mobile receiver to the plurality of fixed transmitters using received phases of the fixed transmitters;

a distance difference calculator for determining distance differences from the mobile receiver to the plurality of fixed transmitters using the time differences of flight; and

a multilateration unit for determining a location of the mobile receiver using the distance differences.

9. The mobile receiver of claim 8, wherein the phase detector further comprises a pseudorandom sequence generator for receiving a seed number and generating the pseudorandom sequence.

10. The mobile receiver of claim 8, wherein the distance difference calculator further comprises a multiplier for generating distance differences from the mobile receiver to the plurality of fixed transmitters by multiplying the time differences of flight with the speed of the sound.

11. The mobile receiver of claim 8, being selected from the group consisting of a mobile phone, a smartphone, a laptop computer, a tablet computer, and a recorder.

12. A non-transitory computer-readable medium for audio localization, the computer-readable medium comprising instructions that, when executed by a computer, cause the computer to:

receive phase offsets of a plurality of fixed transmitters;

detect an audio localization signal from each of the plurality of fixed transmitters;

determine a received phase of the audio localization signal from each of the plurality of fixed transmitters, wherein the received phase is determined by performing one of fast Fourier transform and Delay Locked Loops on a pseudorandom sequence;

determine time differences of flight from the mobile receiver to the plurality of fixed transmitters using relative times of flight;

determine distance differences from the mobile receiver to the plurality of fixed transmitters using the time differences of flight; and

determine a location of the mobile receiver using distance differences to the plurality of fixed transmitters by performing multilateration using the distance differences.