Re: [Discuss-gnuradio] Packet Decoder Breaking when adding noise

[Matthew J. Brandsema]

Hello,

I thought the pink color means everything is 8 bits, so I set K = 8.  So I 
guess I was confused.

When I set it to 4, I get numbers back in the same range as my input numbers 
(0-15), but they are wrong.  

See attached images for flow chart and matlab plots.

Thanks for the advice about the visualization blocks.  I will put that on my 
"to do" list!  
________________________________________
From: Müller, Marcus (CEL) address@hidden
Sent: Monday, November 19, 2018 12:44 PM
To: address@hidden; Matthew J. Brandsema; address@hidden
Subject: Re: [Discuss-gnuradio] Packet Decoder Breaking when adding noise

Hi Matt,

why did you use K=8, then? As far as I can see, a 16-QAM carries
log_2(16)=4 bit of data per symbol, not 8.

Also: packet decoder is in the "deprecated" category for good reason:
it randomly, non-debuggably (as far as I can tell) drops data.

While you're at it, I'd recommend replacing your WX visualization
blocks with their Qt counterparts – we've already removed WX from the
current development version of GNU Radio, and it won't be part of GNU
Radio 3.8.

Best regards,
Marcus

On Mon, 2018-11-19 at 16:17 +0000, Matthew J. Brandsema wrote:
> Hello,
>
> Thanks for your replies!
>
> When I do that, the demodulator outputs unpacked bytes (0s and 1s).  I tried 
> using the “Pack K Bits” and “Unpacked to Packed” blocks separately (setting K 
> = 8) and it did not work.
>
> By “did not work” I mean, my input into the modulator were numbers between 0 
> and 15, and when I pack 8 bits at a time, I get numbers between 0 and 255.
>
> ---------------------------------------
> Matt Brandsema
> Assistant Research Professor
> Applied Research Laboratory at Penn State University
> Phone: c: (201) 259-3584 w: (814) 865-5783
>
> From: Achilleas Anastasopoulos [mailto:address@hidden
> Sent: Monday, November 19, 2018 10:15 AM
> To: Matthew J. Brandsema <address@hidden>; address@hidden
> Subject: [Discuss-gnuradio] Packet Decoder Breaking when adding noise
>
> ...neither do you want the extended FEC encoder/decoder.
>
> Just send random symbols through the QAM modulator, add noise and demodulate 
> with the QAM demodulator.
>
> Achilleas
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

qam_flowchart_2.png
Description: qam_flowchart_2.png

qam_matlab_plots.png
Description: qam_matlab_plots.png