[Discuss-gnuradio] BTW, feature request (Re: costas ambiguity and correlate-and-sync block in qpsk)

[Andy Walls]

On Fri, 2016-04-01 at 09:18 -0400, Andy Walls wrote:

> In the generated *.py script I added one line near the end:
> 
>     print tb.get_modulated_preamble_untrimmed()
> 
> So you can so this:
> 
>       $ source <path_to_target>/setup_env.sh
>       $ ./Rx_syncd.py | grep -v volk | sed -e 's/(//g' -e 's/)//g' > foo.txt
>       $ octave 
>       octave:1> x = csvread('foo.txt');
>       octave:2> t = [1:length(x)];
>       octave:3> plot(t,abs(x))
>       octave:4> plot(t,arg(x)/pi)
> 
> and see why I picked the values I did to trim the modulated preamble to
> the correct set of samples.

It would be really nice, if from within GRC, a supporting tool could
spawn display what the modulate vector blocks will generate. :) 

Regards,
Andy

> The modulator that generates the reference sequence has a pretty long
> delay, and the first copy of the preamble it outputs is a little
> distorted at the first symbol.  That's why I snipped out the second copy
> of the preamble.
> 
> Regards,
> Andy  
>