Audio-based method for determining device distance
Systems and methods directed to determining the distance between two devices are disclosed. The systems and methods utilize a Bluetooth connection between a first device, such as a smartphone with an acoustic transducer, and a second device, such as an earbud with an embedded microphone, and the audio capturing capabilities of the second device to determine a distance between the two devices. The first device plays audio via the acoustic transducer. This audio is captured by a microphone of the second device. The second device transmits data including the captured audio back to the first device via the Bluetooth connection. The first device calculates a time delay from the playing of the audio to the reception of the data over the Bluetooth connection. The first device then calculates the distance based on the time delay, the latency constant, and the speed of sound.
1. A method for determining a distance between two devices, comprising:
playing audio at a first device via an acoustic transducer;
recording, via a microphone of a second device, the audio played by the first device;
subsequent to recording the audio played by the first device via the microphone of the second device, sending the audio recorded by the microphone of the second device to the first device via a Bluetooth connection;
determining a time delay based on the audio played at the first device and the audio recorded via the microphone of the second device; and
determining a distance between the first device and the second device based on the time delay and a latency constant of the Bluetooth connection between the first device and the second device, wherein the latency constant of the Bluetooth connection is a known latency constant associated with Bluetooth Low Energy Audio (LE Audio), and wherein determining the distance between the first device and the second device comprises multiplying the difference of the time delay and the latency constant of the Bluetooth connection by the speed of sound.
2. The method of claim 1 , wherein the Bluetooth connection is a Broadcast Isochronous Stream.
3. The method of claim 1 , further comprising, subsequent to the microphone of the second device recording the audio, transmitting timing information to the first device, wherein the timing information relates to a reception time of the microphone recording the audio.
4. The method of claim 3 , wherein determining the time delay is further based on the timing information.
5. The method of claim 1 , wherein the distance is determined by the first device.
6. The method of claim 1 , wherein the Bluetooth connection is a Connected Isochronous Stream.
7. The method of claim 1 , wherein the audio is played at ultrasonic frequencies.
8. The method of claim 1 , further comprising determining a location of the first device based on the distance between the first and second devices.
9. The method of claim 8 , wherein determining the location of the first device further comprises:
moving the first device relative to the second device; and
determining a second distance between the first and second devices;
wherein determining the location of the first device is further based on the second distance.
10. The method of claim 8 , wherein determining the location of the first device further comprises:
moving the second device relative to the first device; and
determining a second distance between the first and second devices;
wherein determining the location of the first device is further based on the second distance.
11. The method of claim 1 , further comprising determining a location of the second device based on the distance between the first and second devices.
12. The method of claim 11 , wherein determining the location of the first device further comprises:
moving the first device relative to the second device; and
determining a second distance between the first and second devices;
wherein determining the location of the first device is further based on the second distance.
13. The method of claim 11 , wherein determining the location of the first device further comprises:
moving the second device relative to the first device; and
determining a second distance between the first and second devices;
wherein determining the location of the first device is further based on the second distance.
14. A system for determining a distance between two devices, comprising:
a first device configured to play audio via an acoustic transducer;
a second device comprising a microphone, wherein the microphone is configured to record the audio played at the first device and send the audio recorded by the microphone of the second device to the first device via a Bluetooth connection; and
a processor configured to:
determine a time delay based on the audio played at the first device and the audio recorded via the microphone of the second device; and
determining a distance between the first device and the second device based on the time delay and a latency constant of the Bluetooth connection between the first device and the second device, wherein the latency constant of the Bluetooth connection is a known latency constant associated with Bluetooth Low Energy Audio (LE Audio), and wherein determining the distance between the first device and the second device comprises multiplying the difference of the time delay and the latency constant of the Bluetooth connection by the speed of sound.
15. The system of claim 14 , wherein the first device comprises the processor.
16. The system of claim 14 , wherein the Bluetooth connection is a Connected Isochronous Stream.
17. The system of claim 14 , wherein the first device is a smartphone or tablet computer.
18. The system of claim 14 , wherein the second device is an earbud, hearing aid, audio headset, smart speaker, or set of audio eyeglasses.
19. The method of claim 1 , wherein the known latency constant is less than or equal to 2 μs.
20. The system of claim 14 , wherein the known latency constant is less than or equal to 2 μs.