Segmentation fault

Hi all,

I’ve been working lately to get to work the mimo files from trondeau’s
branch. After some trials, I thought I’ve successfully merged the master
branch into this branch so I could use the mimo files. However, when
trying to run the benchmark_mimo_ofdm.py file a segmentation fault is
happening. I’ve been reading about this error but I don’t know yet where
it
comes from. I’ve checked the “How do I debug GNU Radio in Python” from
the
FAQ to see what to do in this case. I’ve followed the 2 steps suggested
in
this point but I don’t understand the results coming from the (gdb)
backtrace. If anyone has experience with this problem or knows how to
understand this message I would really appreciate any help. I enclose
the
messages I’m getting.

This is what it shows when trying to run benchmark_ofdm_mimo.py:

./benchmark_ofdm_mimo.py
linux; GNU C++ version 4.4.1 [gcc-4_4-branch revision 150839];
Boost_103900; UHD_003.004.000-122b947

27435
Press Enter to continue
Noise voltage: 4.472135955
Frequency offset: 0
Symbols per Packet: 16.0
Samples per Packet: 11520.0

gr_fir_ccf: using 3DNow!
gr_fir_ccc: using 3DNow!Ext
gr_fir_fff: using 3DNow!
Transmitter using 1
Receiver using 2
x

After following the steps suggested it shows:

(gdb) backtrace
#0 gr_ofdm_alamouti_frame_acquisition::calculate_equalizer
(this=0x1137c40, channel=, symbol=,
zeros_on_left=) at
gr_ofdm_alamouti_frame_acquisition.cc:210
#1 0x00007f4b40673f67 in
gr_ofdm_alamouti_frame_acquisition::general_work
(this=0x1137c40, noutput_items=,
ninput_items=, input_items=std::vector of
length
3, capacity 3 = {…}, output_items=)
at gr_ofdm_alamouti_frame_acquisition.cc:245
#2 0x00007f4b40702c65 in gr_block_executor::run_one_iteration
(this=0x7f4b187d7f20) at gr_block_executor.cc:378
#3 0x00007f4b407235c2 in gr_tpb_thread_body::gr_tpb_thread_body
(this=, block=…) at gr_tpb_thread_body.cc:49
#4 0x00007f4b4071c20c in
boost::detail::function::void_function_obj_invoker0<gruel::thread_body_wrapper<tpb_container>,
void>::invoke(boost::detail::function::function_buffer&) () from
/usr/local/lib64/libgnuradio-core-3.4.2git.so.0
#5 0x00007f4b4010cd64 in boost::function0::operator()
(this=) at /usr/include/boost/function/function_template.hpp:989
#6 0x00007f4b3fce1010 in thread_proxy () from
/usr/lib64/libboost_thread.so.1.39.0
#7 0x00007f4b415d665d in start_thread () from /lib64/libpthread.so.0
#8 0x00007f4b40ce9ecd in clone () from /lib64/libc.so.6
#9 0x0000000000000000 in ?? ()

Thanks in advance,

Jorge

On Mon, Feb 20, 2012 at 5:48 AM, Jorge H. <
[email protected]> wrote:

backtrace. If anyone has experience with this problem or knows how to
Press Enter to continue

ninput_items=<value optimized out>, input_items=std::vector of length

#5 0x00007f4b4010cd64 in boost::function0::operator() (this=<value

Hi Jorge,
So what that backtrace is telling you is on the #0 line that the seg
fault
is occurring here:
gr_ofdm_alamouti_frame_acquisition.cc:210

So it’s that file, line 210.

All that does is narrow your search down for where it’s going wrong, but
this one isn’t going to tell you what’s wrong with it.

So you’re doing a 1x2 code. I know when Matt and I left off with this
branch, there were some definite issues, and this might just be one of
them. Have you tried to do a 2x1 MIMO? I’m pretty sure we had that
working.
I can’t really remember…

I’m afraid I can’t help you more right now, yo’re going to have to look
into that file and try to figure out why it’s segfaulting one you. But,
thanks for reading over the FAQ and posting the back trace! And you
figured
out how to merge those two branches, so it sounds like you’re heading in
the right direction!

Tom

Hi,

Actually what I’m trying to do is a 2x1 MIMO, but I was trying to run
the
benchmark with its default set up to see if I had success with the
merging.
As you said, this segmentation fault must appear somewhere when trying
to
implement 2 receivers, when you adjust the parameters for 2 tx antennas
and
1 rx antennas there is no problem to run it.

So, now I think I have this benchmark_ofm_mimo prepared to work I’m
finding
another problems…I am using two USRP2 with XCVR2450 daughterboards in
the
transmitter side and another one in the receiver side (less than 1 meter
of
distance between tx and rx). My first problem comes when setting the
sample
rate, I don’t know if I should set the sample rate in the rx usrp as the
sum of the two sample rates of the tx usrps, or it has nothing to
do…Also, I’ve been reading the UHD/USRP2 application notes and I think
I’ve got how to configure the slave usrp but I am not sure. I enclose my
code so anyone who has any adviece can have a look at it. Appart from
this
issues, my heaviest problem is how to introduce an input into the
transmission chain. I see how packets are made and sent in the
benchmark_ofmd_mimo, but how should I proceed if I want to use my own
source block (in my case it would be a wavfile source)? Thank you for
your
support, I will appreciate any help!

2012/2/20 Tom R. [email protected]

I had forgotten to enclose the code, here it goes!

   # USRP2 sinks

#####################################################################################################

    # slave USRP2
    self.usrp2_sink_slave = uhd.single_usrp_sink(
        device_addr="addr=192.168.20.3",
        io_type=uhd.io_type_t.COMPLEX_FLOAT32,
        num_channels=1,
        )
    _config = uhd.clock_config()
    _config.ref_source = uhd.clock_config.REF_MIMO
    _config.pps_source = uhd.clock_config.PPS_MIMO
    self.usrp2_sink_slave.set_clock_config(_config, 0)
    self.usrp2_sink_slave.set_samp_rate(self.output_samp_rate)
    self.usrp2_sink_slave.set_center_freq(self.center_frequency, 0)
    self.usrp2_sink_slave.set_gain(self.tx_gain, 0)
    # master USRP2
    self.usrp2_sink_master = uhd.single_usrp_sink(
        device_addr="addr=192.168.10.4",
        io_type=uhd.io_type_t.COMPLEX_FLOAT32,
        num_channels=1,
        )
    self.usrp2_sink_master.set_samp_rate(self.output_samp_rate)
    self.usrp2_sink_master.set_center_freq(self.center_frequency, 0)
    self.usrp2_sink_master.set_gain(self.tx_gain, 0)

2012/2/22 Jorge H. [email protected]

This forum is not affiliated to the Ruby language, Ruby on Rails framework, nor any Ruby applications discussed here.

| Privacy Policy | Terms of Service | Remote Ruby Jobs