I have a question about an FFT. I have recorded the vibration of a gearbox with a sampling rate of 48 kHz. The speed of the input is 50 Hz, the speed of the output is 12.5 Hz. At a sampling rate of 48 kHz I have 48000 data points per second and after the output rotates 12.5 times per second I have (48000/12.5) 3840 points per rotation.
Does it make a difference if I use only 3840 points for the FFT (i.e. 1 revolution) or if I use 48000 points and thus have 12.5 revolutions?
If someone has literature on this or can explain to me whether there are rules for this, I would be very grateful.