The problem is in different resolutions of those two signals. The used module has a 24-bit resolution of acquired signal, but Sound File Write Simple.vi
has only 8 or 16-bit resolution. It is expected that if you compare RMS of 24-bit signal that it is going to differ from the same but 16-bit signal.
More information could be found on Sound Data help reference.
If there is a need of saving a raw signal in full 24-bit resolution as a .wav file the Sound File Write.vi
could be used in Sound File Write (I32)
mode with a resolution of 32-bit signed integer and also in combination of tasks:
- Sound File Open.vi
- Sound File Write.vi in Sound File Write (I32) mode
- Sound File Close.vi
It is suggested to use TDMS file formatting
instead. See theTDMS file