Hi all!
Thank you for contributing to gnuradio and providing new users like me
with help.
I have read and worked through some of the guided tutorials. However I
come to a point now where it seems that own Python code has to be
written. Unfortunately I am more like a C++ guy and would appreciate it
if someone could give me some advice.
Let us please take a look at the QPSK transmitter example of tutorial 6
[1]. It gives a nice example and you can play around with the parameters
of the PSK Mod block in gnuradio-companion. What we would like to do is
to change the roll-off factor during runtime using a Qt GUI Range
element (i.e. a slider control) to demonstrate its effect. As the
associated parameter is not underlined in the properties dialogue I
wonder how this can be done during runtime.
When looking at the generated sourcecode it can be seen that an instance
of digital.psk.psk_mod is created in __init__ method and stored in
element self.digital_psk_mod_0. I tried to add code in the slider’s
callback function def set_excess_bw_slider(self, excess_bw_slider).
But it does not show changes in constellation and spectrum plot though
printing debug messages like RRC roll-off factor: 0.15 on the command
line.
I tried:
- to access the excess_bw property of the digital.psk.psk_mod directly
to be modified - to create a new instance of digital.psk.psk_mod in the callback
function and overwriting the original one
(in C++ this would be bad practice probably leading to memory leaks
and might be the same for Python)
I did not really find the documentation of the digital.psk.psk_mod
class, except at [2]. And in the sources themselves [3].
A short hint where to take a closer look would be great!
Thank you in advance
Matthias
[1]
https://raw.githubusercontent.com/gnuradio/gr-tutorial/master/examples/tutorial6/gr-tutorial-qpsk-tx.grc
[2] http://www.reynwar.net/gnuradio/sphinx/digital/blocks.html
[3]
http://gnuradio.org/redmine/projects/gnuradio/repository/revisions/master/entry/gr-digital/python/digital/psk.py
