Matching Devices Based on Information Communicated Over an Audio Channel

1. A method for matching devices, the method comprising: transmitting, by a first device and over an audio channel that is shared between the first device and a second device, a first audio signal, at a first frequency outside a range that a human ear can readily detect, and that encodes a first code comprising a first sequence of bits; transmitting, by the second device and over the audio channel, a second audio signal, at a second frequency outside the range that a human ear can readily detect, and that encodes a second code comprising a second sequence of bits; responsive to receiving the second audio signal over the audio channel, extracting, by the first device, the second code from the second audio signal; responsive to receiving the first audio signal over the audio channel, extracting, by the second device, the first code from the first audio signal; sending, by the first device, the second code to a server; sending, by the second device, the first code to the server; responsive to receiving the first code from the second device and the second code from the first device, determining, by the server, whether the first device is in proximity to the second device; transmitting, by the second device and over the audio channel, a third audio signal, at a third frequency outside the range that a human ear can readily detect, and that encodes the first code; responsive to receiving the third audio signal over the audio channel, extracting, by the first device, the first code from the third audio signal; and determining, by the first device and based on the third audio signal, a distance between the first device and the second device.

2. The method of claim 1 , wherein the first and third audio signals include timestamps, and wherein the first device determines the distance based on the timestamps.

3. The method of claim 1 , wherein the first and third audio signals include timestamps and chirps, and wherein the first device determines the distance based on the timestamps and chirps.

4. The method of claim 1 , wherein the first device determines a relative velocity between the first and second devices based on the second audio signal.

5. The method of claim 1 , wherein the first sequence of bits and the second sequence of bits each comprise 32 bits.

6. The method of claim 1 , wherein the first audio signal has a frequency between approximately 18,000 and 19,000 Hz.

7. The method of claim 1 , wherein the first device and the second device comprise a microphone and/or a speaker for transmitting and receiving audio signals.

8. The method of claim 1 , wherein the first device transmits the first audio signal in response to receiving, at the first device, an indication of an intent of a user of the first device to communicate with a user of the second device; and wherein the second device transmits the second audio signal in response to receiving, at the second device, an indication of an intent of the user of the second device to communicate with the user of the first device.

9. A system, comprising: a first device configured to periodically transmit a first audio signal, at a first frequency outside a range that a human ear can readily detect, and that encodes a first code comprising a first sequence of bits over an audio channel that is shared between the first device and a second device; the second device configured to periodically transmit a second audio signal, at a second frequency outside the range that a human ear can readily detect, and that encodes a second code comprising a second sequence of bits over the audio channel; wherein the first device is further configured to: receive the second audio signal over the audio channel, and extract the second code from the second audio signal; wherein the second device is further configured to: receive the first audio signal over the audio channel, extract the first code from the first audio signal; and transmit a third audio signal, at a third frequency outside the range that a human ear can readily detect, and that encodes the first code; wherein, responsive to receiving the third audio signal over the audio channel, the first device is further configured to: extract the first code from the third audio signal; and determine the distance between the first device and the second device based on the third audio signal; wherein the first device is further configured to send the second code to a server; wherein the second device is further configured to send the first code to the server; and the server configured to determine that the first device is in proximity to the second device upon receiving the first code from the second device and the second code from the first device.

10. The system of claim 9 , wherein the first and third audio signals include timestamps, and wherein the first device is configured to determine the distance based on the timestamps.

11. The method of claim 9 , wherein the first and third audio signals include timestamps and chirps, and wherein the first device is configured to determine the distance based on the timestamps and chirps.

12. The system of claim 9 , wherein the first device is further configured to determine a relative velocity between the first and second devices based on the second audio signal.