It is easy to start the filter design tool from the gnu radio companion. If I
use octave without gnu radio companion, how should I start the filter design
tool from GUI (or Octave command window)?
I could be wrong but I though gnu radio companion used Python for underlying calculations, not octave
In MATLAB command window, I can simply type "fitlerDesigner" to bring up the
filter design GUI. Is there a similar way to do it in Octave command window?
I do not believe Octave has a graphical filter design tool implemented. The signal package does have a good number of compatible filter design functions implemented that likely run underneath that GUI. See