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The OpenSignals Mobile app is designed for sensor data acquisition using biosignalsplux and BITalino devices on Android devices.
However, with the current version of the app, it is not possible to define the types of sensors being used during the acquisition, reason for which only the raw digital sensor data is acquired and displayed, with no conversion of the data being conducted.
This How-To shows how the data conversion can be conducted by opening the acquisition files in the OpenSignals (r)evolution desktop software.
The OpenSignals Mobile acquisition files are stored on the internal memory of your device. You can find these files in the "OpenSignals" folder, as seen in the screenshot below of the Android file manager (My Files).
Transfer your OpenSignals files via the Android built-in sharing functions to your computer or connect your device via USB to your computer to transfer the files from the Android Device > OpenSignals folder.
Open the OpenSignals (r)evolution software and enter the Signal Visualization Mode by clicking on the "play" button in the OpenSignals main interface.
Click on the folder icon to open the open-file dialog.
In the open-file dialog, navigate to your file, select it and open it by clicking on the OK button. Afterwards, the signal will be visualized in the OpenSignals software.
As no sensor type selection has been made in the OpenSignals Mobile app, only the raw digital sensor values will be displayed as highlighted in the screenshot below, with the sensor type being set to RAW (1) and the signal values ranging between 0 and 60.000 (see Note 2 at the end of this post for more information).
Click on the arrow next to "RAW" (3) to open a dropdown menu with all the available sensor types, and select the type that corresponds to your sensor (in this case ECG).
Afterwards, the raw digital sensor data will automatically be converted to the original physical unit of the sensor, as seen in the screenshot below where the sensor values now range between -1.5mV and 1.5mV (4) as the sensor type is now set to "ECG" (4).
The converted signal information will be stored in a new file .H5 with a _converted filename extension being added to the original file name. The new file will only be created after exiting the signal visualization mode (auto-save feature should be turned on).
Original file name: SampleECG.txt
New converted file name: SampleECG_convrted.h5
The raw digital signal values range between 0 and (2^n_bits) -1 with n_bits being the sampling resolution selected for the acquisition of 8 or 16-bit.