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+--- Thread: Logging stops with long experiments (/showthread.php?tid=1796)
Logging stops with long experiments - Andreas Weskamp - 09-09-2023
Hi,
I want to do a rather long experiment which lasts around 15-20 minutes.
While testing I encountered some issues. The experiment seems to stop at some point and all data is lost.
Is there a maximum time for an experiment or is there an other issue?
Also I would really like to have a mode where the data is safed while logging. Its really annoying to lose all data only because the app was closed or because the lockscreen jumped in.
With best regards,
Andreas Weskamp
RE: Logging stops with long experiments - Jens Noriʇzsɔɥ - 09-09-2023
Typically, it‘s the out-of-memory killer of the smartphone OS that kicks in on long measurements. There is nothing we can do about that and it also depends on other apps running in the background, so it is hard to quantify when it happens. Accelerometer or gyroscope data collection on Android can rather quickly lead to this. You could check if reducing the rate has an effect.
A lockscreen or putting phyphox into the background should not lead to data loss. Collecting data in the background would require some fundamental changes in the code – and there are substantial restrictions on (at least) iOS. We have added the option “Proximity lock” to the settings so that you could avoid unintended touch events.
For the time being, the app is not really built for offline long term measurements. You could find a remedy by writing the data to a web or MQTT client by the REST API, https://phyphox.org/wiki/index.php/Remote-interface_communication, or network connections, https://phyphox.org/wiki/index.php/Network_Connections (requires changes to the .phyphox file). Alternatively, you could send data to a microcontrolller.
RE: Logging stops with long experiments - Andreas Weskamp - 09-10-2023
That sounds good.
I was able to solve my issues by reducing the datarate from maximum to 20Hz. This is still much faster than I need.
My smartphone does not get "out of memory" for at least 30 minutes with this datarate, which is aswell more time than I need.
I will look into the other solutions aswell. Specially the idea to send the data via bluetooth sounds good because I use a microcontroller with bluetooth connection at the moment anyway.
Thank you for your fast reply
