Get timestamp from PolarHrData?

[abbjetmus]

Platform your question concerns:

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

SDK version:

Customer app url
Link to app store / play store / your website

Device:

• Grit X2 Pro
• Vantage V3
• Vantage M3
• Polar OH1
• Polar Verity Sense
• Polar H10
• Polar H9
• [ X] Polar 360
• Other
• [ X] Device is not relevant for this question

Description:
Hi! I would like to request timestamp on PolarHrData. Before we got an update with timestamp on PolarPpiData, but it would be nice to have it on all data objects. Although our use case requires at this time on on PolarHrData. Is it possible to get this in next release?

Offline data of PolarHrData does not contain timestamp.

#558

[samulimaa]

Hello, good question.

Reason why PolarHrData does not contain timestamp is due to fact that timestamps are not part of the BLE Heart Rate Service GATT specification:

3.4 Requirements for Time-Sensitive Data

The Heart Rate Measurement characteristic contains time sensitive data and is considered a time-sensitive characteristic, thus the following requirements apply:

Since this service does not provide for a time stamp to identify the measurement time (and age) of the data, the value of the Heart Rate Measurement characteristic shall be discarded if either the connection does not get established or if the notification is not successfully sent to the Client (e.g., link loss).

You could try to implement timestamps on your app using current time + 1s for every sample

[abbjetmus]

@samulimaa but we have it for offline PPI data? Since we have it already for PPI one could use its timestamps to identify what timespans contain real measurements. The reason I mention it is because if you take the sensor off and on again there is no way to know what time did you take it on again. And you get the same problems as #558.

[shahshahani-ee]

In the offiline mode, as @abbjetmus says, this makes the HR useless because you can't know when the device was not being worn. You just have some HR values without knowing which is which.
@samulimaa The method you suggested for having timestamps for HR values is not very useful also for the same reason I mentioned above. You receive some values for a time range, depending on the sync time interval, but you don't know about the gaps in the data.
By the way, what is the difference between the HR in PPI file and the HR file?

[shahshahani-ee]

@samulimaa Any further explanations?

[abbjetmus]

@shahshahani-ee When you store PPI offline, the HR calculations differ from the HR values contained in the PPI data. During motion, those values are always 0 and therefore not useful. However, the HR values stored separately are much more reliable.

#411

[shahshahani-ee]

@abbjetmus As I mentioned earlier, the problem is that we do not know which HR alue belongs to which time point or even time range. It makes it uninterpretable, doesn't it?
Although the HR values in the PPI file are 0 when in motion, but at least we have a sense of time for them.

[abbjetmus]

Yes exactly that is a problem and would be nice if fixed. Your understanding is correct.