Methods, systems, and devices for determining a respiration rate

1. A wearable device comprising:

a sensor configured to capture photoplethysmographic (PPG) signals;

a processor;

a communication interface, wherein the communication interface is configured to connect the wearable device to a remote computing device; and

a controller, configured to:

(i) receive from the sensor over a non-zero time period a PPG signal;

(ii) make a first determination that, during the non-zero time period, the wearable device has moved less than a threshold amount;

(iii) in response to the first determination that, during the non-zero time period, the wearable device has moved less than the threshold amount, determine from the PPG signal each of (1) a respiratory-induced intensity variation (RIIV) signal, (2) a respiratory-induced amplitude variation (RIAV) signal, and (3) a respiratory-induced frequency variation (RIFV) signal;

(iv) determine in each of a plurality of frequency bins a power level of each of the RIIV signal, the RIAV signal, and the RIFV signal;

(v) send to the remote computing device via the communication interface data indicative of each determined power level;

(vi) receive from the remote computing device via the communication interface a signal that includes data indicative of whether the respiration rate is determinable; and

(vii) if the signal indicates that the respiration rate is determinable, determine a respiration rate based on at least two of the RIIV signal, the RIAV signal, and the RIFV signal.

2. The wearable device of claim 1 , wherein the controller is further configured to determine a plurality of preliminary respiration rates, wherein each preliminary respiration is based on at least one of the RIIV signal, the RIAV signal, and the RIFV signal.

3. The wearable device of claim 2 , wherein determining the plurality of preliminary respiration rates comprises identifying a peak in at least one of the RIIV signal, the RIAV signal, or the RIFV signal, wherein a frequency of each identified peak is within a range of respiration frequencies.

4. The wearable device of claim 2 , wherein determining the respiration rate comprises combining at least two preliminary respiration rates that are within a threshold of each other.

5. The wearable device of claim 2 , wherein determining the respiration rate comprises combining all of the preliminary respiration rates.

6. The wearable device of claim 2 , wherein determining the preliminary respiration rate from each of the RIIV signal, the RIAV signal, and the RIFV signal comprises identifying a peak in the respective respiratory-induced signal in a range of respiration frequencies.

7. The wearable device of claim 1 , wherein the controller is further configured to

generate a vector that includes each determined power level and wherein sending data to the remote computing device indicative of each determined power level comprises sending the vector.

8. The wearable device of claim 1 , further comprising an output component to provide a notification, wherein the controller is further configured to provide the notification, and wherein the notification is based on the determined respiration rate.

9. The wearable device of claim 8 , wherein the notification includes at least one of a visual output or an auditory output.

10. The wearable device of claim 1 , wherein the sensor comprises a light emitter and a light detector.

11. The wearable device of claim 1 , further comprising:

a mount, wherein the mount secures the device to an external body surface.

12. The wearable device of claim 11 , wherein the external body surface is a location on a wrist.

13. The wearable device of claim 11 , wherein the mount comprises a band that can enclose the wrist.

14. The wearable device of claim 11 , wherein the mount comprises an adhesive substrate.

15. The wearable device of claim 1 , further comprising:

a user interface, wherein the controller is further configured to cause the user interface to indicate information relating to the determined respiration rate.

16. The wearable device of claim 15 , wherein the user interface comprises a display.

17. The wearable device of claim 1 , further comprising a second sensor configured to capture movement data of the wearable device, and wherein the controller is further configured to:

receive, from the second sensor and over the non-zero time period, movement data of the wearable device.

18. The wearable device of claim 17 , wherein the second sensor comprises one or more accelerometers, gyrometers, and/or magnetometers.