[Discuss-gnuradio] Re: Benchmark scripts sending erroneous packets

[Daniel Ali]

Update: After trying quite a few different things in terms of package version and ubuntu installs, I looked at a Wireshark capture of what was going out through the laptop's ethernet port to the radio for both good transmissions and for "high BER" transmissions. In the good packet captures there was a MAC pause packet that would be displayed on the line because the actual data packets must not have been getting processed fast enough. An example of the wireshark capture of this pause packet is attached. The bad transmission capture did not contain any of these MAC pause packets, which I'm guessing is either flooding or corrupting the data being sent from the laptop to the USRP 2. I've attached a screenshot to show how wireshark displays these packets pause packets in the good transmissions. I'm not sure if this is a flaw in GNURadio or Ubuntu, but the Dell Latitude E5500 does not like generating these PAUSE packets for the data being sent to the radio. If anyone has any information on this please let me know. Thanks.

On Wed, Nov 3, 2010 at 11:14 AM, Daniel Ali <address@hidden> wrote:

Hello all, I've got a GNURadio install on two laptops, both of which have version 3.3.0 on them. They are both Dell Latitudes E5500 with Ubuntu 9.10 x86 on them. I have two USRP2s with the correct firmware installed on the SD cards to operate the WBX daughter card (txrx_wbx_raw_eth_20100608.bin). I have been trying to run the out-of-the-box benchmark_tx/rx.py scripts to just get correct packet transfer between the two. At first I found that having the radios too close together was causing the issue but even after moving them apart it still has an unacceptable BER. I followed the install instructions as follows:

1. Install dependencies in the blip of code given for the "sudo apt-get ..." command for Ubuntu 9.10.

2. Download gnuradio-3.3.0, unpack.

3. cd; ./configure; make; sudo make install; sudo ldconfig;

On a another note using a separate computer, a Sony Vaio with GNURadio 3.3.0 installed on Ubuntu 10.04 x86_64 seems to transmit to either of the Dell laptops just fine using the benchmark scripts with no errors at all.

The output on the receive is as follows (Ctrl+c'ed because nothing else was transmitting):

~/Desktop/gnuradio-3.2.2/gnuradio-examples/python/digital: sudo ./benchmark_rx.py -f 910M

>>> gr_fir_fff: using SSE

Requested RX Bitrate: 100k

Actual Bitrate: 100k

ok = False  pktno =    0  n_rcvd =    1  n_right =    0

ok = False  pktno =   85  n_rcvd =    2  n_right =    0

ok = False  pktno =  173  n_rcvd =    3  n_right =    0

ok = False  pktno = 6617  n_rcvd =    4  n_right =    0

ok = False  pktno =  320  n_rcvd =    5  n_right =    0

ok = False  pktno =  401  n_rcvd =    6  n_right =    0

ok = False  pktno =  548  n_rcvd =    7  n_right =    0

ok = False  pktno =  703  n_rcvd =    8  n_right =    0

^C~/Desktop/gnuradio-3.2.2/gnuradio-examples/python/digital: 

The output on the transmit (which seems to runs all at once instead of dot by dot as the Vaio does) is as follows:

~/Desktop/gnuradio-3.2.2/gnuradio-examples/python/digital: sudo ./benchmark_tx.py -f 910M

>>> gr_fir_fff: using SSE

Requested TX Bitrate: 100k Actual Bitrate: 100k

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Does anyone have any suggestions, comments, etc,? Thanks.

--
Daniel Ali
Graduate Student
Electrical and Computer Engineering
Virginia Tech

--
Daniel Ali
Graduate Student
Electrical and Computer Engineering
Virginia Tech

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