Tracking system using audio signals below threshold
View Patent ↗A tracking system may determine the orientation or position of a movable object. The tracking system includes a signal generator that generates a non-audible detection signal in an audible frequency range. A transmitting device transmits the detection signal to a detection device. The transmitting device or the detection device may be positioned on the movable object, and the other may be positioned at a remote location. A processor may determine an orientation or position of the moveable object based on the transmission time between the transmitting device and the detection device.
1. A tracking system, comprising:
a signal generator configured to generate a detection signal, where the detection signal comprises a non-audible sonic signal in an audible frequency range;
a transmitting device configured to transmit the detection signal generated by the signal generator;
a detection device configured to detect the detection signal transmitted by the transmitting device, where either the transmitting device or the detection device is fixed to a headphone unit configured to simulate a surround sound reproduction of audio data, and the other one of the transmitting device and the detection device is located at a fixed position; and
a processing unit configured to determine at least one orientation parameter of the headphone unit based on a transmission time measurement of the detection signal between the transmitting device and the detection device.
2. The tracking system of claim 1 , where the processing unit is configured to determine at least one position parameter of the headphone unit based on a transmission time measurement between the transmitting device and the detection device.
3. The tracking system of claim 1 , where the transmitting device comprises a loudspeaker.
4. The tracking system of claim 3 , where the loudspeaker is configured to transmit the detection signal contemporaneously with an audible sonic signal, where the detection signal is non-audible due to masking by the audible sonic signal transmitted by the loudspeaker.
5. The tracking system of claim 4 , where an amplifier is configured to feed the loudspeaker to transmit the audible sonic signal, where the signal generator is configured to determine a masked threshold of hearing on the basis of output information from the amplifier in order to generate the detection signal at a level to be masked by the audible sonic signal.
6. The tracking system of claim 1 , where the detection device comprises a microphone.
7. The tracking system of claim 1 , further comprising an additional transmitter or detector configured to determine a current sound velocity value.
8. The tracking system of claim 7 , where the transmitting device comprises three transmitters forming a predetermined triangular arrangement, where the detection device comprises three detectors forming a predetermined triangular arrangement, where the processing unit is configured to determine the current sound velocity value and to completely determine orientation and position of the headphone unit on the basis of transmission time measurements between the transmitters and detectors.
9. The tracking system of claim 1 , where the processing unit is configured to determine a single orientation parameter of a head wearing the headphone unit, where the single orientation parameter comprises a rotation angle around a vertical axis of the head.
10. The tracking system of claim 1 , where the detection signal comprises a sonic signal below an absolute threshold of hearing in the frequency range between about 20 Hz and about 16 kHz.
11. The tracking system of claim 10 , where the detection signal comprises a sonic signal below the absolute threshold of hearing in the frequency range between about 100 Hz and about 1 kHz.
12. The tracking system of claim 10 , where the detection signal comprises a sonic signal below the absolute threshold of hearing in the frequency range above about 10 kHz.
13. The tracking system of claim 1 , further comprising a masking determination unit, where the detection signal is masked by other sonic signals, where the masking determination unit is configured to determine a masked threshold of hearing for the detection signal on the basis of a detection of the other sonic signals.
14. The tracking system of claim 13 , where the masking determination unit is configured to select a sound level or frequency for the detection signal on the basis of the determined masked threshold of hearing.
15. The tracking system of claim 1 , where the processing unit is configured to set at least one characteristic of the audio data for the headphone unit based on the at least one orientation parameter of the headphone unit.
16. The tracking system of claim 1 , where the processing unit is configured to modify at least one characteristic of the audio data to correspond to a detected change in the at least one orientation parameter of the headphone unit.
17. The tracking system of claim 16 , where the headphone unit is configured to receive the audio data and produce a surround sound reproduction of the audio data for a wearer of the headphone unit, where the surround sound reproduction includes at least one virtual sound source;
where the processing unit is configured to modify the at least one characteristic of the audio data so that the surround sound reproduction at the headphone unit represents a corresponding change to a listener's spatial orientation relative to the virtual sound source.
18. The tracking system of claim 1 , where the transmitting device comprises a loudspeaker within a vehicle, where the processing unit is configured to modify at least one characteristic of content provided by an entertainment or information unit of the vehicle for the headphone unit based on a detected change in the at least one orientation parameter of the headphone unit.
19. A tracking system, comprising:
a transmitting device configured to transmit a non-audible sonic signal in an audible frequency range;
a detection device configured to detect the non-audible sonic signal, where the transmitting device or the detection device is associated with a headphone unit configured to receive audio data and produce a surround sound reproduction of the audio data for a wearer of the headphone unit; and
a processing unit configured to determine an orientation or position of the headphone unit based on a transmission time measurement of the non-audible sonic signal between the transmitting device and the detection device, where the processing unit is configured to set at least one characteristic of the audio data for the headphone unit based on the orientation or position of the headphone unit.
20. A method, comprising to acts of:
generating a detection signal, where the detection signal comprises a non-audible sonic signal in an audible frequency range;
transmitting the detection signal;
detecting the detection signal, where transmission or detection of the detection signal occurs at a headphone unit configured to simulate a surround sound reproduction of audio data; and
determining at least one orientation parameter of the headphone unit based on a time measurement between the transmission and detection of the detection signal.
21. The method of claim 20 , where the act of transmitting comprises masking the detection signal through transmission of the detection signal contemporaneously with an audible sonic signal, where the detection signal is non-audible due to masking by the audible sonic signal.
22. The method of claim 20 , where the act of determining comprises:
determining a current sound velocity value; and
determining the orientation parameter of the headphone unit on the basis of the time measurement and the current sound velocity value.
23. The method of claim 20 , where the act of generating comprises:
determining a masked threshold of hearing for the detection signal based on a detection of audible sonic signals or based on information from an amplifier that outputs audible sonic signals; and
selecting a sound level and/or frequency of the detection signal based on the determined masked threshold of hearing.
24. The method of claim 20 , further comprising the act of:
setting at least one characteristic of the audio data for the headphone unit based on the at least one orientation parameter of the headphone unit.
25. The method of claim 20 , further comprising the acts of:
determining that a change occurred in the at least one orientation parameter of the headphone unit; and
modifying at least one characteristic of the audio data for the headphone unit to correspond to the change in the at least one orientation parameter of the headphone unit.