[op25-dev] Success running OP25 with GNURadio 3.7.11 [2 Attachments]

Alex alex323@gmail.com [op25-dev] op25-dev at yahoogroups.com
Wed May 10 14:49:43 UTC 2017


Hi all,

OP25 (specifically scope.py) doesn't seem to work out of the box with
the latest version of GNU Radio, seemingly because it relies on
deprecated components (WX widgets). Today I was able to massage the
code to get it semi-functional with 3.7.11 using my own custom flow
graph, which was reverse engineered from the scope.py application. When
I tune it to a voice channel of a Phase I system I am able to hear
audio, which I consider a success.

The changes I made to the code base are located here[0], and attached
to this email is my flow graph. I hope that this is helpful to people
new to the project.

I do have some questions though:

1. How can this flow graph be optimized? I am not a radio expert by any
means, and while this flow graph works, I don't know *why* it works.
Importantly, the MPSK Receiver block is deprecated and set to be removed
in a future release[1], so I'd like to change it to something more
idiomatic.

2. What do the veriables "beta", "gain_mu", "alpha", "gain_omega",
"if_rate", and "symbol_deviation" mean? How were they chosen? Why do
they work?

-- 
Alex

[0] https://github.com/centromere/op25
[1] https://github.com/gnuradio/gnuradio/issues/1083
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