Testing

GNU Radio
1

I am testing some blocks to understand the synchronization in ofdm . I
edited c++ files & put std::cout for all variables in
frequency_modulator_fc_impl.cc and multiply_cc_impl.cc and then I
rebuilt
using cmake…/ then make then sudo make install . But when I run the
python file “./top_block.py” I got an empty output from vector sinks
also
I got only the values of variables in multiply_cc_impl.cc on terminal .
so
why the values of variables of frequency_modulator_fc_impl.cc aren’t
shown
on terminal !!!

Thanks.

Here is the python file

#!/usr/bin/env python
##################################################

Gnuradio Python Flow Graph

Title: Top Block

Generated: Wed Apr 23 05:43:13 2014

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

from gnuradio import blocks
from gnuradio import eng_notation
from gnuradio import gr
from gnuradio.eng_option import eng_option
from gnuradio.filter import firdes
from grc_gnuradio import wxgui as grc_wxgui
from optparse import OptionParser
import wx
from gnuradio import digital
from gnuradio import analog

class top_block(grc_wxgui.top_block_gui):

def __init__(self):
    grc_wxgui.top_block_gui.__init__(self, title="Top Block")

    ##################################################
    # Variables
    ##################################################
    self.samp_rate = samp_rate = 32000
    fft_len=512
    cp_len=128
    n_sync_words=1
    frame_length_tag_key = "frame_length"

    ##################################################
    # Blocks
    ##################################################
    self.blocks_vector_source_x_0 = blocks.vector_source_c((1, 1,

1,0,0,0,1,0,1), False, 1, [])

    self.sync_detect = digital.ofdm_sync_sc_cfb(fft_len, cp_len)
    self.delay = blocks.delay(gr.sizeof_gr_complex, fft_len+cp_len)
    self.oscillator = analog.frequency_modulator_fc(-2.0 / fft_len)
    self.mixer = blocks.multiply_cc()
    self.hpd = digital.header_payload_demux(
        n_sync_words+1,       # Number of OFDM symbols before

payload
(sync + 1 sym header)
fft_len, cp_len, # FFT length, guard interval
frame_length_tag_key, # Frame length tag key
“”, # We’re not using trigger tags
True # One output item is one OFDM symbol
(False would output complex scalars)
)

    self.blocks_vector_sink_x_0 = blocks.vector_sink_b(4096)
    self.blocks_vector_sink_x_1 = blocks.vector_sink_b(4096)

    ##################################################
    # Connections
    ##################################################

    self.connect((self.blocks_vector_source_x_0, 0),

(self.sync_detect))
self.connect((self.blocks_vector_source_x_0, 0), self.delay,
(self.mixer, 0), (self.hpd, 0), (self.blocks_vector_sink_x_0, 0))
self.connect((self.sync_detect, 0), self.oscillator,
(self.mixer,
1))
self.connect((self.sync_detect, 1), (self.hpd,
1),(self.blocks_vector_sink_x_1, 0))

    #if debug_log:
     #   self.connect((sync_detect, 0),

blocks.file_sink(gr.sizeof_float, ‘freq-offset.dat’))
# self.connect((sync_detect, 1),
blocks.file_sink(gr.sizeof_char, ‘sync-detect.dat’))

QT sink close method reimplementation

def get_samp_rate(self):
    return self.samp_rate

def set_samp_rate(self, samp_rate):
    self.samp_rate = samp_rate

if name == ‘main’:
import ctypes
import sys
if sys.platform.startswith(‘linux’):
try:
x11 = ctypes.cdll.LoadLibrary(‘libX11.so’)
x11.XInitThreads()
except:
print “Warning: failed to XInitThreads()”
parser = OptionParser(option_class=eng_option, usage="%prog:
[options]")
(options, args) = parser.parse_args()
tb = top_block()
tb.Start(True)
tb.Wait()
print tb.blocks_vector_sink_x_0.data()
print tb.blocks_vector_sink_x_1.data()

2

You should attached the files where you put the std::cout.
The std::cout should be in the work() function.

3

Here is the file . I wrote std::cout in the work() , why I don’t see the
output from this file on terminal after rebuilding ?!

#ifdef HAVE_CONFIG_H
#include “config.h”
#endif

#include “frequency_modulator_fc_impl.h”
#include <gnuradio/io_signature.h>
#include <gnuradio/fxpt.h>
#include <math.h>
#include <boost/math/special_functions/trunc.hpp>

namespace gr {
namespace analog {

frequency_modulator_fc::sptr
frequency_modulator_fc::make(double sensitivity)
{
  return gnuradio::get_initial_sptr
    (new frequency_modulator_fc_impl(sensitivity));
}

frequency_modulator_fc_impl::frequency_modulator_fc_impl(double

sensitivity)
: sync_block(“frequency_modulator_fc”,
io_signature::make(1, 1, sizeof(float)),
io_signature::make(1, 1, sizeof(gr_complex))),
d_sensitivity(sensitivity), d_phase(0)
{
}

frequency_modulator_fc_impl::~frequency_modulator_fc_impl()
{
}

int
frequency_modulator_fc_impl::work(int noutput_items,
                                  gr_vector_const_void_star

&input_items,
gr_vector_void_star &output_items)
{
const float in = (const float)input_items[0];
gr_complex out = (gr_complex)output_items[0];

  for(int i = 0; i < noutput_items; i++) {
    std::cout<<"d_phase "<<d_phase<<std::endl;
    d_phase = d_phase + d_sensitivity * in[i];
    std::cout<<"d_sensitivity "<<d_sensitivity<<std::endl;
    std::cout<<"in[i] "<<in[i]<<"where i] "<<i<<std::endl;
    std::cout<<"then d_phase= "<<d_phase<<std::endl;
    while(d_phase > (float)(M_PI)){
      d_phase -= (float)(2.0 * M_PI);
      std::cout<<"d_ph>MPI then d_ph= "<<d_phase<<std::endl;
      }

    while(d_phase < (float)(-M_PI)){
      d_phase += (float)(2.0 * M_PI);
      std::cout<<"d_oh<M_PI then d_ph= "<<d_phase<<std::endl;
      }

    float oi, oq;

    gr_int32 angle = gr::fxpt::float_to_fixed (d_phase);
    gr::fxpt::sincos(angle, &oq, &oi);
    std::cout<<"angle "<<angle<<" oq "<<oq<<" oi "<<oi<<std::endl;
    out[i] = gr_complex(oi, oq);
    std::cout<<" out[i] "<<out[i]<<" where i= "<<i<<std::endl;
  }

  return noutput_items;
}

} /* namespace analog /
} / namespace gr */

2014-04-30 10:37 GMT+02:00 Activecat [email protected]:

4

On Fri, May 2, 2014 at 8:46 AM, Activecat [email protected] wrote:

I have not much idea beyond this.
The std::cout in work() should show something if executed.

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Did you install the file after rebuilding it? That said, I don’t know
what you’re expecting to gain from this exercise. You’re going to see
a bunch of numbers fly by really fast. Wouldn’t plotting the output
with one of the waveform analysis tools be more useful?

5

On 03.05.2014 05:05, West, Nathan wrote:

Did you install the file after rebuilding it? That said, I don’t know
what you’re expecting to gain from this exercise. You’re going to see
a bunch of numbers fly by really fast. Wouldn’t plotting the output
with one of the waveform analysis tools be more useful?

I very much want to second this. We have all these nice plotting utils,
it helps to use them.

M

6

On Fri, May 2, 2014 at 5:57 PM, Sara Chérif [email protected]
wrote:

Here is the file . I wrote std::cout in the work() , why I don’t see the
output from this file on terminal after rebuilding ?!

It seems like the work() function is not called at all by the scheduler.
Probably the ofdm sync block doesn’t produce any output to feed into
your
custom block.
I have not much idea beyond this.
The std::cout in work() should show something if executed.