Oh, I also added complex_to_arg and probably a complex to mag^2.
I don't know if either of these have controlport functionality.
I might have added other blocks I suppose, I'm typing this all from memory.
-Andy
On Sat, Apr 2, 2016 at 8:11 PM, Andy Walls <a...@silverblocksystems.net>
wrote:
> Hi Arik:
>
> On Sat, Apr 2, 2016 at 7:41 PM, Landsman, Arik <arik.lands...@tufts.edu>
> wrote:
>
>> Hi Andy,
>>
>> Still looking it over, but one thing jumps out right away - for some
>> reason I couldn't execute either Rx_syncd_2.grc or the Rx_syncd.py. getting
>> the same error in both cases:
>>
>> ""
>> Generating:
>> '/home/ubuntu/Desktop/MSProject/alternateVersions/Rx_syncd_2.py'
>>
>> Executing: '/usr/bin/python2 -u
>> /home/ubuntu/Desktop/MSProject/alternateVersions/Rx_syncd_2.py'
>>
>> Using Volk machine: sse4_1_64
>> Thrift: Sat Apr 2 19:05:54 2016 TServerSocket::listen() BIND 9090
>> terminate called after throwing an instance of
>> 'apache::thrift::transport::TTransportException'
>> what(): Could not bind: Transport endpoint is not connected
>> ""
>>
>> does this look familiar by any chance?
>>
>
> It looks like a GNURadio ControlPort / Apache Thrift error.
>
> I took your flowgraph and modified it slightly, only adding a few blocks:
> -modulate_vector
> -skip_head
> -keep_1_in_n
> -qt_time_sink
> -feedforward_agc
> -multiply const
> -qt gui range
>
> One of those might be doing it. Disable skip_head, keep_1_in_n, and the
> constellation sink they connect to. Hopefully it's one of them.
> Otherwise, you didn't drop a control port related block on the flowgraph
> did you?
>
> FWIW, I also modified the Polyphase clock sync filter taps, the Corr_Est
> symbols, and changed a few 3.14's to math.pi.
>
>
>>
>> Also could you elaborate a bit on what you did with
>>
>> ""
>> $ 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)
>> ""
>>
>> at the very least where can I find setup_env.sh?.
>
>
> If you build GNURadio with the PyBOMBS build system and install in a
> target directory somewhere, PyBOMBS generates this environment file which
> is essential to run GNURadio Companion and gnuradio scripts properly. If
> you are using the GNURadio supplied by your distribution, then sourcing a
> setup_env.sh file is not necessary.
>
>
>
>
>> . wondering what <path_to_target> may be.
>> I suppose you then pipe a portion of the stream in Rx_syncd.py into
>> foo.txt to parse with octave?
>>
>
> Yes, I just have it emit the complex samples vector that the
> modulate_vector block creates, and then inspect the samples in octave. You
> can do it in MatLab or Python or Excel, or whatever.
>
>
>> going to try it if I find setup_env.sh on my end. and once I can run
>> Rx_syncd.py... )
>>
>> Thanks,
>> Arik
>>
>
> And another, "Oh by the way" for when things are working. In the
> flowgraph I sent, I mark the phase correction on the last symbol of the
> preamble - where the phase correction was measured. This means, that the
> previous symbols in the preamble, if they suffered a phase rotation, may
> not get corrected by the costas loop. You can "fix" that by setting the
> corr_est tag marking delay to 0, to mark the first symbol in the preamble
> with the phase correction. This is OK as long as you are very close to the
> correct center frequency. The measured phase rotation will become less
> correct the farther you move from the measurement point at the peak of the
> correlation, if you don't have good frequency lock when performing the
> correlation.
>
>
> Regards,
> Andy
>
>
>>
>>
>>
>> ________________________________________
>> From: Andy Walls [a...@silverblocksystems.net]
>> Sent: Friday, April 01, 2016 9:18 AM
>> To: Landsman, Arik
>> Cc: discuss-gnuradio@gnu.org
>> Subject: Re: [Discuss-gnuradio] costas ambiguity and correlate-and-sync
>> block in qpsk
>>
>> Hi Arik,
>>
>> I have attached a slightly improved flowgraph and a hand edited .py
>> file.
>>
>> The only modifications to the flowgraph from before, is that I set the
>> reference samples for the corr_est block to start at the _middle_ of the
>> first symbol of the preamble and stop at the _middle_ of the last symbol
>> in the preamble; I also ensured the phase_est and time_est tags stayed
>> marked at the center of the last symbol of the preamble. This has two
>> benefits:
>>
>> 1. The phase_est value will not be thrown off by the end of symbol
>> transition to a different unknown symbol after the preamble.
>> 2. The correlation won't be sensitive to the unknown symbols before and
>> after the preamble.
>>
>> In other words, it was a mistake to have the correlation reference
>> sequence start and end at the symbol transition times. :P
>>
>> 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.
>>
>> 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
>>
>>
>> On Thu, 2016-03-31 at 22:04 -0400, Andy Walls wrote:
>> > Hi Arik,
>> >
>> > Try the attached flowgraph. I didn't get to put everything back in, but
>> > it demonstrates the principal.
>> >
>> > 1. Observe the corr_est block correlates to your preamble bytes.
>> > 2. Slide the phase offset around:
>> > a. observe the phase changing/wrapping in the time plot of the output of
>> > the correlator
>> > b. observe the phase_est tag value approximately matches the value of
>> > the phase offset slider.
>> > c. Observe the constellation rotate as you change the phase offset.
>> > d. Observe your decoded bits stay the same.
>> >
>> > Regards,
>> > Andy
>> >
>> >
>> >
>>
>>
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