Re: [Discuss-gnuradio] BBN 802.11b updated: Barker spreading works

[Colby Boyer]

Hey Ulrika,

I think I fixed that bug.  I couldn't really test the rx/tx files because I do not have a USRP2 anymore.  I think I made that change that will fix it. . . .I think it has something to do with how the parameters are set in send_pkt.  Feel free to play with it if it doesnt work.  

The rx file should be able to receive from the AP.  I'll look at it later tonight and make sure that file is functioning correctly.  The decimation/spb rate for the receive filter might need fine tuning in order to receive packets from an AP.

Regarding this error:
[alot of:]  File "/gnu-radio-path/lib/python2.
> 5/site-packages/gnuradio/gr/hier_block2.py", line 48, in __getattr__
>
>
>     return getattr(self._hb, name)
> RuntimeError: maximum recursion depth exceeded

I get this a lot too, but not everytime.  I've notice that this sometimes comes up if I have a poorly written line of python in the init blocks.  However, it only appears once and a while for me.  I am using GNURadio version 10689.

Eric, do you know what causes this bug or have you seen/heard of it before?

Regards,
Colby Boyer

On Mon, Jun 15, 2009 at 5:38 AM, Ulrika Uppman <address@hidden> wrote:

Hi!
I'm happy to hear that you have made some progress in this work. Myself I haven't had so much time to struggle with this problem lately.
I updated your code from the CGRAN svn and tried it out. However I'm having some problems. What version of the gnuradio is required for this code? I'm running on revision 10899 at the moment. Below are some error printouts from running your updated code:

When running  bbn_80211b_test.py I get the following:
[alot of:]  File "/gnu-radio-path/lib/python2.5/site-packages/gnuradio/gr/hier_block2.py", line 48, in __getattr__
   return getattr(self._hb, name)
RuntimeError: maximum recursion depth exceeded

When I'm running bbn_80211b_tx.py I get the following:
Sending pkt  0
Traceback (most recent call last):
 File "./bbn_80211b_tx.py", line 191, in <module>
   main()
 File "./bbn_80211b_tx.py", line 181, in main
   send_pkt(payload + " " + str(n), bit_rate, False);
 File "./bbn_80211b_tx.py", line 106, in send_pkt
   tb.send_pkt(payload, send_rate, eof)
TypeError: send_pkt() takes at most 3 arguments (4 given)

And when I'm running bbn_80211b_rx.py I don't get any error messages, but I cannot receive any data from an AP. (Haven't tried to receive data from another USRP2 since the tx doesn't work.)

Best regards
/Ulrika
________________________________________
Från: discuss-gnuradio-bounces+ulrika.uppman=foi.se@gnu.org [discuss-gnuradio-bounces+ulrika.uppman=foi.se@gnu.org] f&#246;r Colby Boyer [address@hidden]
Skickat: den 15 juni 2009 04:45
Till: address@hidden; Valerio, Danilo
Ämne: [Discuss-gnuradio] BBN 802.11b updated: Barker spreading works

Hey All,

I fixed the code in the pkt.py file so that DSSS with the barker code now works.  The main issue was the length of the barker interpolation filter was way too short (like 8).  I changed it so that it is now sample per baud * 11.  Additionally the barker sequence needs to be time reversed on the receive side so that the correct match filter is formed. Otherwise the nice autocorrelation properties of barker will go away.

I am only able to test it using the test script with a channel filter and gaussian noise and so far it has been a success there with both 1 and 2 Mbps modulation rates.  Can someone test with USRP2?  Also the BER seems to be much better as compared to just the RRC filter.  Hopefully this will make TX/RX much more robust.

The code is uploaded to the CGRAN svn under the branch/usrp2_version in the bbn project directory.

Cheers,
Colby Boyer