Timestamp for PPI measurements.

polarofficial / polar-ble-sdk

Repository includes SDK and code examples. More info https://polar.com/en/developers

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Timestamp for PPI measurements. #484

Open hamletAppsfactory opened 3 weeks ago

hamletAppsfactory commented 3 weeks ago

Platform your question concerns:

[ ] Android
[ ] iOS
[ ] Other
[X] Platform is not relevant for this question

Device:

[ ] Polar OH1
[ ] Polar Verity Sense
[ ] Polar H10
[ ] Polar H9
[ ] Other
[X] Device is not relevant for this question

Why the Timestamp for PPI (PolarPpiData) measurements are deprecated and always 0? Is it possible to get them somehow?

orestesgaolin commented 3 weeks ago

In our case we just assume that the last PPI sample comes from current instant, and samples before that are x ms before that e.g. if we get a batch of [300,500,900] ms then they are at [t-(300+500+900), t-(500+900), t-900] where t is now

hamletAppsfactory commented 1 week ago

Thanks for the reply, let's assume this is not an offline recording and there is no startTime provided by the device(or SDK). What is now in this case: 1) the time of receiving the first measurement 2) the time of sending the command to the device to start the streaming? In my case with OH1 there is a difference between those two points around 3-5 seconds.

orestesgaolin commented 1 week ago

I'd assume it's more likely that time of receiving the measurement is closer to reality.

I suspect the algorithm that determines the PPI values requires several cycles to establish a baseline. When switching to PPI mode you can notice that HR stream stops for a while and starts over.