Medisana ViFit connect Review

In the post I want to share some experiences with the Medisana ViFit connect, which is an activity tracker. It counts steps and bins them in intervals of 15min. Memory of the device is sufficient for 15 days of recording and battery lifetime is around 6 days. It has an OLED display that saves you from having to wear an additional wrist watch.

Medisana outlines that for optimal usage the activity tracker should be wrist worn. I disagree with this as my intuition is that the activity tracker overestimates the number of steps when wrist worn, especially when you spend a big portion of the day sitting.

Bluetooth 4.0 is used to upload recorded data to a smartphone, tablet, etc.. The synchronization is slow and not always successful. The app does not build an offline database, so internet connection is required while synchronizing. Moreover, synchronization always has to be explicitly initiated and is not executed as a background service.
The activity tracker has a Micro USB port for recharging.  Interestingly, hooking it up to a Linux PC loaded a driver for this USB to UART bridge. Maybe this leaves some potential for hacking? It would be great to be able to download the activity data without having to upload them to the cloud first. Another idea would be to reduce the binning interval of the activity tracker to eg. 1min to be able to draw conclusions about the types of activity (eg. running, biking, hiking, sitting, etc.) from the recorded data.

In my opinion the accompanying website cloud.vitadock.com fails to provide much insightful information (Maybe there is a legal requirement that prevents them from interpreting the activity data for the user?). It is possible to export the activity data as .csv files and I find it helpful to create two additional plots as follows:
Firstly, a histogram showing the averaged activity for all days that usually falls within the individual times of the day. An exemplary plot is shown in Fig. 1 based on mock data. It is also interesting to compare working days and weekend days in this plot.

Fig. 1.: Relative activity over time of the day

Secondly, a scatter plot showing the correlation between sleep time and the active time during the next day as shown in Fig. 2. Again this plot is based on mock data.

Fig. 2.: Active time versus sleep time