Devices, systems, and methods for detecting multiple devices within a predetermined proximity

1. A device for use in ranging relative to a remote device, comprising

an acoustic emitter;

an acoustic receiver;

a short-range wireless radio frequency transceiver; and

a controller communicatively coupled to each of the acoustic emitter, the acoustic receiver, and the short-range wireless radio frequency transceiver, the controller being configured to:

cause the acoustic emitter to emit a first acoustic signal at a first frequency;

monitor, via the acoustic receiver and for a first predetermined amount of time following an emission of the first acoustic signal by the acoustic emitter, for a first acoustic response signal generated by the remote device at a second frequency that is different from the first frequency; and

responsive to receiving the first acoustic response signal within the first predetermined amount of time, (1) calculate a first distance between the device and the remote device based on a duration between emitting the first acoustic signal and receiving the first acoustic response signal, and (2) broadcast, via the short-range wireless radio frequency transceiver, a first message including the distance and a first identifier associated with at least one of the device or the short-range wireless radio frequency transceiver,

wherein the second message is selected based on having a Received Signal Strength Indicator (RSSI) that is greater than a threshold RSSI and that is greater than any other RSSI of any other message received by the device and communicated via a protocol used to broadcast the first message.

2. The device of claim 1 , wherein, responsive to not receiving the acoustic response signal within the first predetermined amount of time, the controller is further configured to:

monitor, via the acoustic receiver, for a second acoustic signal generated by the remote device at the first frequency; and

responsive to receiving the second acoustic signal:

cause the acoustic emitter to emit a second acoustic response signal at the second frequency; and

monitor, via the short-range wireless radio frequency transceiver, for a second message having a second distance measurement and a second identifier, the second message generated by the remote device.

3. The device of claim 2 , wherein, responsive to receiving the second message, the controller is further configured to at least one of (i) record the second message in a memory or (ii) transmit the second message upstream for recordation by a remote server.

4. The device of claim 2 , wherein:

causing the acoustic emitter to emit the first acoustic signal and monitoring for the first acoustic response signal constitutes a first mode of operation;

monitoring for the second acoustic signal constitutes a second mode of operation; and

wherein the controller is further configured to revert to the first mode of operation from the second mode of operation responsive to not receiving the second acoustic signal within a second predetermined amount of time.

5. The device of claim 2 , wherein, responsive to receiving the second acoustic signal, the controller is configured to cause the acoustic emitter to emit the second acoustic response signal after a predetermined delay less a known turn-around duration of the device.

6. The device of claim 1 , wherein the first predetermined amount of time (t 1 ) is defined as:

t 1 =t d1 +t d2 +( pd−tt )

wherein:

t d1 is a duration that an acoustic signal travels from a first point to a second point less than or equal to 10 feet away from the first;

t d2 is a duration that an acoustic signal travels from the second point to the first point;

pd is a predetermined delay; and

tt is a known turn-around duration of the device.

7. A method for ranging between a first device and a second device, each of the first device and the second device respectively having an acoustic emitter, an acoustic receiver, a short-range wireless radio frequency transceiver, and a controller communicatively coupled to each of the acoustic emitter, the acoustic receiver, and the short-range wireless radio frequency transceiver, the method comprising:

emitting, via the acoustic emitter of the first device, a first acoustic signal at a first frequency;

monitoring, via the acoustic receiver of the first device and for a first predetermined amount of time following an emission of the first acoustic signal by the acoustic emitter of the first device, for a first acoustic response signal generated by the second device at a second frequency that is different from the first frequency; and

responsive to receiving the first acoustic response signal within the first predetermined amount of time, (1) calculating, via the controller of the first device, a first distance between the first device and the second device based on a duration between emitting the first acoustic signal and receiving the first acoustic response signal, and (2) broadcast, via the short-range wireless radio frequency transceiver of the first device, a first message including the distance and a first identifier associated with at least one of the first device or the short-range wireless radio frequency transceiver of the first device,

wherein the second message is selected based on having a Received Signal Strength Indicator (RSSI) that is greater than a threshold RSSI and that is greater than any other RSSI of any other message received by the device and communicated via a protocol used to broadcast the first message.

8. The method of claim 7 , wherein, responsive to not receiving the acoustic response signal within the first predetermined amount of time, the method further includes:

monitoring, via the acoustic receiver of the first device, for a second acoustic signal generated by the second device at the first frequency; and

responsive to receiving the second acoustic signal:

emitting, via the acoustic emitter of the first device, a second acoustic response signal at the second frequency; and

monitoring, via the short-range wireless radio frequency transceiver of the first device, for a second message having a second distance measurement and a second identifier, the second message generated by the second device.

9. The method of claim 8 , wherein, responsive to receiving the second message, the method further includes at least one of (i) recording the second message in a memory of the first device or (ii) transmitting the second message upstream for recordation by a remote server.

10. The method of claim 8 , wherein:

emitting the first acoustic signal and monitoring for the first acoustic response signal constitutes a first mode of operation;

monitoring for the second acoustic signal constitutes a second mode of operation; and

wherein the method further includes reverting to the first mode of operation from the second mode of operation responsive to not receiving the second acoustic signal within a second predetermined amount of time.

11. The method of claim 8 , wherein, responsive to receiving the second acoustic signal, the method further includes emitting, via the acoustic emitter of the first device, the second acoustic response signal after a predetermined delay less a known turn-around duration of the first device.

12. The method of claim 7 , wherein the first predetermined amount of time (t 1 ) is defined as:

t 1 =t d1 +t d2 +( pd−tt )

wherein:

t d1 is a duration that an acoustic signal travels from a first point to a second point less than or equal to 10 feet away from the first;

t d2 is a duration that an acoustic signal travels from the second point to the first point;

pd is a predetermined delay; and

tt is a known turn-around duration of the device.

13. A device for use in ranging, comprising

an acoustic emitter;

an acoustic receiver;

a short-range wireless radio frequency transceiver; and

a controller communicatively coupled to each of the acoustic emitter, the acoustic receiver, and the short-range wireless radio frequency transceiver, the controller being configured to:

compose a list of remote devices within a predetermined Received Signal Strength Indicator (RSSI) range by causing the short-range wireless radio frequency transceiver to emit a first wireless signal and respectively registering a first response wireless signal received from each of the remote devices within the predetermined RSSI range; and

for each of the remote devices:

transmit, via the short-range wireless radio frequency transceiver, a second wireless signal requesting a response;

monitor, via the acoustic receiver and for a first predetermined amount of time following a transmission of the second wireless signal, for a first acoustic response signal generated by one of the remote devices; and

responsive to receiving the first acoustic response signal within the first predetermined amount of time, (1) calculate a first distance between the device and the one of the remote devices based on a duration between transmitting the second wireless signal and receiving the first acoustic response signal, and (2) broadcast, via the short-range wireless radio frequency transceiver, a third wireless signal including an acknowledgement of receiving the first acoustic response signal.

14. The device of claim 13 , wherein the predetermined RSSI range is based on a strength of a radio frequency signal received approximately 10 feet away from a source of the radio frequency signal.

15. The device of claim 13 , responsive to receiving the first acoustic response signal within the first predetermined amount of time, the controller is further configured to at least one of (i) record the second message in a memory of the device or (ii) transmit the second message upstream for recordation by a remote server.

16. The device of claim 13 , wherein the first predetermined amount of time (t 1 ) is defined as:

t 1 =t d1 +t d2 +( pd−tt )

wherein:

t d1 is a duration that a radio frequency signal travels from a first point to a second point less than or equal to 10 feet away from the first;

t d2 is a duration that an acoustic signal travels from the second point to the first point;

pd is a predetermined delay; and

tt is a known turn-around duration of the device.