How to set parameters for usrp_nbfm_ptt.py

GNU Radio
1

Hi,
I just buy two sets of RFX900 a few days ago. now I can run
usrp_siggen.py
and usrp_fft.py normally now. But when I try to run usrp_nbfm_ptt.py for
a
full duplex test, I can hear nothing in both sides. I check the source
code
and find self.set_transmit(False) in the init of ptt_graph, so I
change
it to self.set_transmit(True) in PC_A with microphone input and leave it
False in PC_B with speaker output. Now there are some noise output in
PC_B,
but still don’t have any voice ouput come from my input from microphone
in
PC_A. I am try to search in archives of this maillist and read the
source
codes by myself, but still have not find the answer. Could anyone help
me
for below question:

  1. Do I need to change the usrp_nbfm_ptt source code to test RFX900? If
    so,
    how to change for simplex and duplex respectively?
  2. I see rx_subdev_spec, tx_subdev_spec, audio_input and audio_output
    options may be detect by program automtically if we don’e spectify, is
    it
    right? I also find side A seems to be first priority if automatically
    detected, but why there are still signal input and output in side B at
    the
    same time?
  3. How to set parameters in command line to run usrp_nbfm_ptt.py, my
    current
    setting is: ./usrp_nbfm_ptt.py -f 900e6 for both PC_A and PC_B.
  4. after showup the gui, I can’t move the sliders in the control panel,
    although there are sliders there. Is it normal?

Thank you very much!

Sincerely,
Zhifeng