If you want to make sure your setup is working smoothly and there's no Bluetooth trouble i.e. data loss, see below how you can monitor this during your experiment.
Windows app - mbtStreamer
There's two indicators of data loss. The top metric represents current data loss percentage, or to be precise, number of lost packets averaged in the last 5 seconds of streaming. If this is at 0%, you are not losing data currently.
The bottom metric shows total number of lost packets during your streaming session. If this is not 0, you had some data loss happen during that session.
This number is in packets i.e. samples of data. For example, if this =2, that means you lost 2 samples. If you're sampling at 250Hz, this is 2 x 4ms = 8ms of data.
If you are sampling at 1000Hz, this is 2 x 1ms = 2ms of data. So, based on this metric you can calculate your data loss during the entire session.
Android - SmartingProApp
The app will give you a notification in Signal view if there's data loss happening currently.
In the recorded EEG file, you can also easily locate the trials in which data loss occurred.
If the software doesn't receive a new Bluetooth packet (EEG sample), it keeps repeating the last one it received. So, you'll see flat lines across all channels at the same time. Once we receive a valid, new sample, we keep recording EEG i.e. flat lines end.