Re: [Discuss-gnuradio] Port flowgraph from Python to C++

[Martin Braun]

On 07/29/2014 11:53 PM, Stefan Oltmanns wrote:
> Hello,
> I was able to create a flowgraph in GRC to demodulate a signal
> (low-frequency battery telegram of wireless microphones). Now I started

Awesome! Are you planning to publish the code somewhere?

M

> to port the generated code from Python to C++.
> I had to realize that some blocks are Python-only, like the FM
> Demodulator. I was able to rebuild the FM Demodulator in C++, for one
> exception: The FM demodulator uses optfir, which is implemented in
> Python, so it cannot be used in C++. So I replaced it with firdes (I
> noticed the parameter difference in transition band end and transition
> band width).
> Another thing is that the Frequency-Xlating-Filter uses a complex
> lowpass, but in C++ I could only find a complex band-pass, so I used a
> band-pass with lower frequency 0, is that the same?
> 
> Also it works, the signal is a lot noisier and the result cannot be
> decoded in many cases. I think the reason are the different filters.
> Could that be the reason?
> As I understood, both optfir and firdes create just a bunch of numbers
> and that´s it. As my program is not going change the filter parameters
> they could be hardcoded in my program, right?
> 
> Best regards
> Stefan
> 
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