Re: [Discuss-gnuradio] ofdm benchmark issue

[Tom Rondeau]

On Thu, Feb 14, 2013 at 2:44 PM, Pablo Belzarena <address@hidden> wrote:

Hi everyone, I am newbie on gnuradio and I have a question about  ofdm
benchmark. If I use benchmark_tx.py and benchmark_rx.py I have a good
performance, (an error rate below 10%).
However, if I only modify the benchmark_tx.py and I add only a
time.sleep(1) between   send_pkt(payload) like is shown in the
following code of the benchmark_tx.py:

 while n < nbytes:
        if options.from_file is None:
            data = "" - 2) * chr(pktno & 0xff)
        else:
            data = "" - 2)
            if data == '':
                break;
        payload = struct.pack('!H', pktno & 0xffff) + data
        send_pkt(payload)
        n += len(payload)
        print (n)
        if options.discontinuous and pktno % 5 == 4:
            time.sleep(1)
        pktno += 1
        time.sleep(1)                     # this is the line added
    send_pkt(eof=True)

In this case, the packets error rate is above 50% and  there are some
underruns on the transmitting screen.

Could someone explain me where is the problem and how can I solve it?

Thanks in advance,

Pablo Belzarena.

This code must not be setting the burst conditions for the UHD driver correctly. There's some ongoing work that's overhauling the OFDM code for a lot of the major advancements in GNU Radio since these benchmark scripts were first written. I think this is the best place to look at that code development:

git://github.com/benreynwar/gnuradio.git

Using the branch 'ofdm'. Not sure how usable it is right now, though.

Tom