Heart Sensor

[BugsyBob]

Is there a way to get the heart sensor to provide a reading for each heartbeat instead of by some non-related frequency? I know you can set the frequency and the default seems to be 1 Hz.I need delta heart-rate slope information and have been trying to derive it from the 1 second data. It works, but could be better.

[JonFitbit]

Sorry, that's all the API provides at this time. What are you trying to create?

[BugsyBob]

I have an early heartbeat sometimes during normal sinus rhythm which looks like a missing heartbeat. I have also been diagnosed with Afib. I'm looking for the delta between heartbeats and I think the optics are seeing that missing heartbeat. My Sense watch usually is many BPM above what the ECG or Pulse-Ox meter shows, sometimes up to 50% higher. I have been successful in vibrating the watch when this high delta condition is found, but I was hoping for more accuracy. It would be helpful to know how the watch calculates it's HR display data. There seems to be about a 8-10 second delay from the heartbeat until the display. I put it on my wife's arm and it took about 10 seconds to change slowly from my HR to hers and then another 10 when I put it back on. Does it keep the highest reading during that time? It does seem to show correctly while I'm sleeping.

[JonFitbit]

The sensor does enter a different mode during night/sleep, so that could be why you see differences at night. The BPM is a calculated value, so it's not just showing a raw sensor value and therefore the algorithm would prevent it instantly jumping from one reading to the next, which also explains the slight delay in changes. 

[BugsyBob]

Thanks for the information so far. You have been a big help. I have been having large delta BMP changes at night after using the bathroom and laying back down. My BPM changes from anywhere around 100 to anywhere around 60 after being in bed for a minute or two. Does the sleep mode change slowly from the non-sleep mode? Is it possible to get any further information about the algorithms so I can understand what is happening? Unrelated, is there any way to get text from the companion to anywhere else? I have been successful moving text from the watch to the companion, but it dies there unless in developer mode.

[JonFitbit]

Unfortunately we don't publish our algorithms, and I'm not sure how frequently the sensor mode changes, but you could peek under the device and see if the red LED is active.

With regard to getting data from the companion, you'd need to send it to a webserver using fetch() post. https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch

[BugsyBob]

Thank you, I understand about the algorithms. Can you say whether the non-sleep one prioritizes a higher BPM. I don't understand why my day time readings are always higher than the average HR, and sometimes by  a lot. As for the fetch(), it looks like I could get a file to a Web server, but not easily to the user. Might be nice to be able to upload to the users notification or message area.