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[Discuss-gnuradio] How to change PSK roll-off during runtime (or an arbi
From: |
Matthias Weber |
Subject: |
[Discuss-gnuradio] How to change PSK roll-off during runtime (or an arbitrary parameter) |
Date: |
Mon, 17 Aug 2015 16:38:08 +0200 |
User-agent: |
SOGoMail 2.2.17a |
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
- [Discuss-gnuradio] How to change PSK roll-off during runtime (or an arbitrary parameter),
Matthias Weber <=