[Hackrf-dev] Project on the decoding of WiFi-Networks

[West, Nathan]

On Mon, May 25, 2015 at 8:00 AM, Andreas Diehm <andreas.diehm at gmail.com>
wrote:

> Hello fellow HackRF-Devs,
>
> I'm a german student working on a project in which we try to read the Data
> of a WiFi-Network using the HackRF and Gnu Radio Companion.
> I have some questions about some peculiar things that have happend to me
> while exercising the lessons on SDR by Michael Ossmann.
> I did the Radio in GRC and it worked only once, all the other times it
> gives me "UaUaUa" as an Error-Message, is this related to my Hardware or
> related to some bugs on the HackRF and what is the meaning of "U" and "a"?
>

Ua in GNU radio language is basically "audio underrun". See
http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#I-have-a-receiver-with-acoustic-output-and-keep-getting-aUaUaU-errors
for more info.


>
> Another question is about the filters in GRC. While trying to set up a
> filter for my (very basic and unfinished) flowgraph (
> http://abload.de/img/bsbphudi.png ) I was unable to figure out, what
> value the "transition width" needs. Is there a way of calculating it, trial
> and error unfortunatly turned out to be unsuccsessful.
>

Transition width is the frequency gap between your pass band edge and your
stop band edge. If you look at any textbook on DSP you should see a good
picture. Your favorite search engine might also turn up good results; it's
a fairly widespread concept.


>
> My last question is, if there is already a flowgraph that decodes
> Wifi-Data, and is it even possible with the HackRF, Gnu Radio Companion and
> a consumer-class PC to do such a complicated action?
>

For a list of nice GNU Radio applications see http://cgran.org (disclaimer:
I'm a co-author of that page). gr-ieee802-11 is there:
http://cgran.org/pages/gr-ieee802-11.html


>
> Best regards,
>
> Andreas Diehm
>
>
Cheers,
-Nathan
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