ST BLE SENSOR APP MICROPHONE

[SAbba.1]

Hello could someone explain me for the FFT LINE COMPARE that is in the ST BLE SENSOR APP for the sensortile.box what are the parameters that appear to edit? and also for the FFT COMPARE, which I understand that it will be the same and the "Name file FFT to compare" that I understand that here I can place an excel as: "output.cvs" and I guess it will compare them.

My doubt is about the treshold that I understand that it will be in dB, that is to say that putting a whole number will be enough, the "number line to compare" if I do not understand what it would be, and I do not know if it is asking too much but I do not fully understand the .cvs that are sent after the bluetooth transmission, I am supposed to be recording an audio of 5kHz to see if I notice any difference in the excel but I do not see anything.

[Federica Bossi · Accepted solution]

Ciao  @SAbba.1 ,

The main idea of the FFT compare function is that if there is at least one line with data higher than the threshold, the function returns a 1, pointing that there is a difference.

The threshold is in the measurement unit of the data in input, so for an audio FFT is the dB, for accelerometer data is mg and so on.

The number line to compare in the FFT compare function refers to the number of line to compare before stopping, so if you put 5, the FFT compare will check the first 5 lines (it always jumps the first line, to discard the DC component, so in reality it will be from the second to the sixth), if you leave a 0 as parameter the fw goes on until the end of the file to compare.

While, the number of line to compare in the FFT line compare function is the index of the single line to compare, so the fw will only check that specific line.

In any case, the firmware is able to perform these compare functions only if the file is compatible, so you should record it with the FFT compare training app or a custom app similar to that.

If my reply answered your question, please click on Accept as Solution at the bottom of this post. This will help other users with the same issue to find the answer faster :)