Time Stamp Drift with large datasets iOS RuuviStatoin App

I am hoping to acquire High Frequency data (every few seconds) from my Ruuvi Tags (firmware v3.30.4). Using iOS RuuviStation App (v 0.7.5), “Keep Connection” and Data Logging Interval “ALL,” seems to save this data on my iPhone 12 Pro Max. But Exporting it produces a dataset that does not agree with my other datasets (Meazurem Cloud, Ruuvi Tag SYNC to a different iPhone, and local Airport METAR – all of which are in excellent agreement!)

Looking closer at these enormous exports, the Time Stamps seem to start out in good agreement with my other datasets, but then start to slowly drift over time. Within a few days, the patterns in Temperature, etc., are still obvious, but their timeline has been stretched way out. The data Exported has a current time stamp on its final entry, but it reflects data that was actually collected many hours or days ago. (And the most recent measurements are not actually exported.)

There is evidence that these Time Stamps reset correctly AFTER an Export (or iPhone power cycle), but the older Time Stamps are still incorrect and there is lost data. So, a series of Exports over several days all agree with each other, which makes me think that the iOS database itself is flawed, instead of just the Export process.

There appears to be a problem with the database in iOS when this High Frequency storage is attempted.

I have done a more detailed analysis and I can provide my spreadsheet if you need it for diagnosis, but it is quite large. (The Time Stamp stretching is not correctable with a simple linear correction, so the stretching must be Quadratic or larger… And, again, the current data and Time Stamp may correct itself after each Export or iPhone Power Cycle.)

I have updated to iOS RS App v0.7.6 and will report back if that changes anything.

Thanks for looking at this.

1 Like

Thank you for the detailed report.

I opened issue about it at Time Stamp Drift with large datasets · Issue #598 · ruuvi/com.ruuvi.station.ios · GitHub

Again, if someone wants to look at my detailed spreadsheet on the matter, I can send a link. Just let me know who to send it to.

Please send the link to otso@ruuvi.com, I’ll make sure it reaches the devs debugging the issue

As I mentioned before, I updated the RuuviStation App to (iOS) v0.7.6 and collected additional data sets (this past weekend. The Time Stamp drift issue seems to have cleared up.

I also looked at some slightly longer data sets using firmware 3.30.4 and iOS v0.7.6 (different iPhone); and I did not see the Time Stamp drift there, either.

So, I can only conclude that there was some bad interaction between firmware 3.30.4 and iOS RS App v0.7.5 that has now been resolved.

I believe that you can safely mark this issue closed.

1 Like

Ok, thank you for the follow-up