Reg calculation of BER/SNR using gnuradio UHD

GNU Radio
1

Hi

I am working in WINLAB and I have been using gnuradio UHD image for
running
some of the programs I have previously worked in summer.

I came across a post in this forum, where few months ago someone has
asked
how to calculate BER and Tom has given him the answer to look into
digital-bert folder.

http://gnuradio.org/redmine/projects/gnuradio/repository/revisions/master/show/gnuradio-examples/python/digital-bert

When I tried to run the program it said it cannot find USRP and I guess
this
is due to the problem of firmware image I am using.

Does anyone have any idea of what image I should use for these programs?
It
will be much helpful if someone can help me out with this.

Thank you

–
Regards

Shantharam Balasubramanian
MS in Electrical and Computer Engineering
Rutgers University
Ph:732-543-6863
Email:[email protected]

2

Hi Ben,

Thanks a lot for the reply. One of our colleagues downloaded the
gnuradio
version 3.1.2 and we are using that version. I don’t know if we need to
download the latest version of gnuradio (3.4.0) and run that.

Now, the thing is, the benchmark_tx and benchmark_rx programs in
gnuradio-examples/python/digital sub-folder work properly. That means,
the
receiver receives the packets transmitted by the transmitter. However,
when
we try running the benchmark_rx and benchmark_tx programs of
gnuradio-examples/python/digital-bert subfolder, it fails to find usrp.

We give the following command to run the benchmark_rx program of bert
subfolder:

./benchmark_rx.py -f 2.412G -r 1M

We have also tried with: ./benchmark_rx.py -f 2.412G -r 1M -w 2 (We are
using USRP2)

The program shows the following error message:

usrp: failed to find usrp[0] (If we give -w 2, it says failed to find
usrp[2])

Runtime error: can’t open usrp

We don’t know if we are giving wrong commands because similar commands
work
well for benchmark programs in the python/digital sub-folder. Your help
will
be very appreciated.

Thanks,

–
Regards

Shantharam Balasubramanian
MS in Electrical and Computer Engineering
Rutgers University
Ph:732-543-6863
Email:[email protected]

3

On 09/27/2011 05:00 PM, shantharam balasubramanian wrote:

However, when we try running the benchmark_rx and benchmark_tx

Thanks,

–
Regards

The examples you are using are designed strictly for a USRP1, using
the “classic” interface. You have presumably modified your USRP2
for “UHD”, which does not interoperate with programs using the
“classic” API.

I believe Tom R. is busy working on updating most of the important
examples to use UHD, which will allow, among other things,
the ability to use any of the USRP hardware, more-or-less
seamlessly with most of the examples.

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

4

Hi

When I run it in USRP1 nodes, I don’t get the error as before, that says
it
cannot find USRP1.

But the benchmark_tx program says “Failed to tune to center frequency”.
I
then tried to send it in 2 MHZ and also in 2 GHZ frequency, but it still
doesn’t work.

Can anyone tell me why it’s happening.? It will be greatly helpful if
someone can help me out with this center frequency setting process.

Thanks

Shantharam

5

Hi

Thanks for the reply. And yes you are correct. It just works for USRP1
alone, though it seeks to give the option of selecting the USRP number.

6

I am running into the same problem here. I used to have a test script
that uses Side B of a USRP1 to Tx a file to Side A. Suffice to say,
that involves me starting Side A in Rx mode first, and then starting
Tx’ing at Side B. That was done using a FLEX900 + DBX setup.

I was able to borrow a newer WBX board to replace the FLEX900, which
only supports UHD. But after installing UHD+GR3.4, asking Side B to Tx
to Side A is no longer possible.

Does anyone see this functionality of simultaneously supporting two
daughterboards coming back? I ask this question since all USRP2’s only
have one daughterboard anyway; so debating whether it’d make sense for
me to get my hands on a B100 + 2xWBX.

Thanks, =)
Jerry

7

On 09/27/2011 06:12 PM, shantharam balasubramanian wrote:

Hi

When I run it in USRP1 nodes, I don’t get the error as before, that
says it cannot find USRP1.
USRP1s didn’t require any “wire format” or firmware/FPGA changes to
support UHD, so both “classic” and “UHD” programs will work,
with USRP1s provided that the daughtercard in use is “pre-UHD”.
Development of the “classic” branch was frozen quite some time ago, so
any cards that are “new” won’t work in anything but the UHD
environment.

But the benchmark_tx program says “Failed to tune to center
frequency”. I then tried to send it in 2 MHZ and also in 2 GHZ
frequency, but it still doesn’t work.

What daughtercard are you using?

What rev of Gnu Radio are you using? I strongly suggest always trying
to run with some quite current.

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium