Sometimes in GnuRadio there’s two ways to do what seems to be the same thing…

  1. To set the gain: either the set_gain function of each daughterboard, or the set_pga function of the usrp source/sink
  2. To design a filter, you can either use the optfir or the gr.firdes functions

The 2 filter design methods are described in:

  • gnuradio-core/src/python/gnuradio/
  • gnuradio-core/src/lib/general/

Optfir attempts to design “optimal” FIR filters using the Remez exchange algorithm. Note that the optfir.high_pass is broken: # FIXME high_passs is broken…