Re: [Discuss-gnuradio] Problem GNU RADIO WIFI tranceiver

[Bastian Bloessl]

Hi,

Regarding sudo: You use a flowgraph with a TUN/TAP interface. If it
doesn't already exists, GNU Radio tries to create it, which requires
root privileges. I'd recommend to just create the interface before
starting GNU Radio. See the rx_demo.sh script in the apps folder to see
how this can be done.

Regarding the setup: It looks like you are trying to start with the most
complex setup (TUN/TAP, networking, etc.) There are also wifi_{rx,tx}
examples. Try to run them on different PCs with antennas and make sure
they work.

Regarding 'D's on the console: This doesn't mean "data", but that UHD
had to drop samples because your PC didn't process them fast enough.
It's documented in the manual:
https://files.ettus.com/manual/page_general.html
Please, try running sender and transmitter on different PCs and start
with the simpler flowgraphs. Once you connect GNU Radio to the network
stack, it might send all kinds of messages that you didn't want to send.
(E.g. Dropbox discovery, etc).

Regarding the constellation points, please try to adjust the RX and TX
gains. There are sliders in the GUI. I'm not sure if 75% work well with
a loopback cable and 30dB of attenuation.

Regarding the time sink: I'm not sure what you expected to see. In
simulations, there are only the samples that you send. It's the frame
plus 10k zero padding at beginning and end. If you use hardware, the
receiver will sample at a constant rate. In your case, the devices
produces 10e6 samples per second (independent from any frame
transmissions). The sink displays 1024. If you wanted to "see
everything", this would be nearly 10k frames per second. Neither your
GPU, nor you screen, nor your eye can do this. GNU Radio, therefore,
just grabs some samples and displays them. Chances that you see the
frame like in the simulations are very small. Try to use a trigger and
play with the level. Then you should see something similar.
(Middle-click on the widget.)

Regarding thread priority: It is unrelated, but if you want to get rid
of the warning, please do as suggested in the manual:
https://files.ettus.com/manual/page_general.html

Best,
Bastian




On 7/26/19 2:37 PM, timothe dissaux wrote:
> Hi everyone,
> i'm facing a problem on gnu radio concerning a wifi tranceiver made by
> Bastian Bloessl.
> 
> I have summarized the issue in the attached pdf.
> if you are missing any information, do not hesitate to ask me for it.
> 
> I would like to point out that I am a beginner on gnu radio
> 
> In the hope that someone will be able to unlock me
> Sincerely
> Timothy, an engineering trainee in the field of electronics based at
> Heriot-Watt University (Scotland)
> 
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 

-- 
Dr. Bastian Bloessl
Secure Mobile Networking Lab (SEEMOO)
TU Darmstadt, Germany

www.bastibl.net
GitHub/Twitter: @bastibl

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