FFT/LPC...

FFT section
Bandwidth (Window Length) Sets the window size in points and corresponding frequency resolution in hertz.
Applied window length (ms) You can vary the actual window of data over which the FFT takes place. It will be limited to the maximum allowed by the sample rate.
Frequency range (Hz) Sets the limit of the frequency to display the data.
Average step size (ms) Sets the step size for average FFT operation.
LPC section
LPC number of coefficients Sets the number of coefficients for LPC analysis.
Draw LPC If checked the LPC trace is displayed on the top of the FFT trace in blue.
Display Format
Absolute (dB) Displays the FFT data in absolute form -20 dB to desire maximum.
Relative Displays the FFT data in relative form from zero at the top to negative values.
Print/BMP
Prints and saves the FFT data according to these parameters.
Add Frequency grid with spacing (Hz) Displays frequency grids with the desire interval.
Add Power grid with spacing (dB) Displays power grids with the desire interval.