Doubt about benchmark_rx and benchmark_tx

GNU Radio
1

We are trying to install USRP and set it up to transmit and receive
packets.
We are novices at this. We are trying to use benchmark_tx.py and
benchmark_rx.py. We have Flex2400 daughter boards mounted on the
motherboard. We have two such boards connected to two different
computers.
We are following the procedure given in the README file but we are not
able
to receive anything using the benchmark_rx.py file.

Our command line arguments are:
TX: ./benchmark_tx.py -f 2.4G -v --discontinuous

RX: /benchmark_rx.py -f 2.4G --rx-gain=90 -v

We confirmed that the Tx was transmitting some packets. We also tried
sending our own packets and this was also transmitted by the TX. However
there was no reaction from the RX side other than the verbose arguments
being printed. The callback function is not called at all which suggests
that the no packets are received. We checked the transmitted spectrum
using
usrp_fft.py and we were able to detect the transmitted signal spectrum
in
the graph. This was visible only when a valid transmission was going on,
thus confirming that the TX seems to be working fine.

What are we doing wrong? Should we do something in RX to receive this
signal/packet. Also we are using antennas and not a cable.

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2

On Wed, Nov 14, 2007 at 09:50:42AM -0800, NCSU wrote:

Which version of GNU Radio are you using?
One of the tarballs (3.1.1), or the trunk, or something older?
What OS and distribution are you using?

–rx-gain=90 seems awfully high.

RX: /benchmark_rx.py -f 2.4G --rx-gain=90 -v
Eric

3

We are using the latest stable gnuradio (3.1) code by check out using
the
following command:
( as given in the Build Guide)
svn co http://gnuradio.org/svn/gnuradio/branches/releases/3.1 gnuradio

We are running it on Fedora Core 7 (fc7) with kernel version 2.6.21-1
(2.6.21-1.3194.fc7 ).
We varied the rx-gain to different values and 90 being the highest, but
that did not help much !
We can generate signal and receive it using usrp_fft.py script, but
benchmark_rx.py is not receiving it.
We also tried changing the distance between two USRP boards between 1
and 3
m, even that did not fetch anything.

Please provide your inputs if you can figure out what could be going
wrong.

Thanks,
Ashwin.

Eric B. wrote:

packets.

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