Re: [Discuss-gnuradio] USRP2 FM TX and FM RX working together

[Jorge Miguel]

This is my grc generated file. It is probably that now the sample rates are not adjusted because I tried everything to make my receiver work.
I would appreciate any help. I remind you that modulator and demodulator work when they are alone but they don't when running together.

Many thanks,
Jorge.

GRC CODE:

<flow_graph>
<timestamp>Wed Sep 22 08:14:26 2010</timestamp>
−
<block>
<key>variable_slider</key>
−
<param>
<key>id</key>
<value>tune_filter</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>label</key>
<value>LPF Cutoff Freq</value>
</param>
−
<param>
<key>value</key>
<value>75000</value>
</param>
−
<param>
<key>min</key>
<value>15000</value>
</param>
−
<param>
<key>max</key>
<value>150000</value>
</param>
−
<param>
<key>num_steps</key>
<value>1000</value>
</param>
−
<param>
<key>style</key>
<value>wx.SL_HORIZONTAL</value>
</param>
−
<param>
<key>converver</key>
<value>float_converter</value>
</param>
−
<param>
<key>grid_pos</key>
<value/>
</param>
−
<param>
<key>notebook</key>
<value/>
</param>
−
<param>
<key>_coordinate</key>
<value>(0, 127)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>gr_frequency_modulator_fc</key>
−
<param>
<key>id</key>
<value>gr_frequency_modulator_fc_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>sensitivity</key>
<value>0.980</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(454, 315)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>blks2_rational_resampler_xxx</key>
−
<param>
<key>id</key>
<value>blks2_rational_resampler_xxx_0_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>type</key>
<value>fff</value>
</param>
−
<param>
<key>decim</key>
<value>1</value>
</param>
−
<param>
<key>interp</key>
<value>5</value>
</param>
−
<param>
<key>taps</key>
<value>[]</value>
</param>
−
<param>
<key>fractional_bw</key>
<value>0</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(233, 68)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>note</key>
−
<param>
<key>id</key>
<value>Chain1</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>note</key>
<value>MODULATOR</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(233, 9)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>note</key>
−
<param>
<key>id</key>
<value>Chain1_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>note</key>
<value>DEMODULATOR</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(181, 427)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>blks2_rational_resampler_xxx</key>
−
<param>
<key>id</key>
<value>blks2_rational_resampler_xxx_1</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>type</key>
<value>fff</value>
</param>
−
<param>
<key>decim</key>
<value>1</value>
</param>
−
<param>
<key>interp</key>
<value>4</value>
</param>
−
<param>
<key>taps</key>
<value>[]</value>
</param>
−
<param>
<key>fractional_bw</key>
<value>0</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(699, 122)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>wxgui_fftsink2</key>
−
<param>
<key>id</key>
<value>wxgui_fftsink2_0_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>type</key>
<value>complex</value>
</param>
−
<param>
<key>title</key>
<value>FFT Plot</value>
</param>
−
<param>
<key>samp_rate</key>
<value>200000</value>
</param>
−
<param>
<key>baseband_freq</key>
<value>2000000</value>
</param>
−
<param>
<key>y_per_div</key>
<value>10</value>
</param>
−
<param>
<key>y_divs</key>
<value>10</value>
</param>
−
<param>
<key>ref_level</key>
<value>50</value>
</param>
−
<param>
<key>fft_size</key>
<value>512</value>
</param>
−
<param>
<key>fft_rate</key>
<value>50</value>
</param>
−
<param>
<key>peak_hold</key>
<value>False</value>
</param>
−
<param>
<key>average</key>
<value>False</value>
</param>
−
<param>
<key>avg_alpha</key>
<value>0</value>
</param>
−
<param>
<key>grid_pos</key>
<value/>
</param>
−
<param>
<key>notebook</key>
<value/>
</param>
−
<param>
<key>_coordinate</key>
<value>(370, 568)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>audio_sink</key>
−
<param>
<key>id</key>
<value>audio_sink_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>samp_rate</key>
<value>32000</value>
</param>
−
<param>
<key>device_name</key>
<value>plughw:0,0</value>
</param>
−
<param>
<key>ok_to_block</key>
<value>True</value>
</param>
−
<param>
<key>num_inputs</key>
<value>1</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(607, 648)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>usrp2_sink_xxxx</key>
−
<param>
<key>id</key>
<value>usrp2_sink_xxxx_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>type</key>
<value>complex</value>
</param>
−
<param>
<key>interface</key>
<value/>
</param>
−
<param>
<key>mac_addr</key>
<value/>
</param>
−
<param>
<key>interpolation</key>
<value>104</value>
</param>
−
<param>
<key>frequency</key>
<value>fm_freq_mod</value>
</param>
−
<param>
<key>lo_offset</key>
<value>float('inf')</value>
</param>
−
<param>
<key>gain</key>
<value>0</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(874, 283)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>usrp2_source_xxxx</key>
−
<param>
<key>id</key>
<value>usrp2_source_xxxx_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>type</key>
<value>complex</value>
</param>
−
<param>
<key>interface</key>
<value/>
</param>
−
<param>
<key>mac_addr</key>
<value/>
</param>
−
<param>
<key>decimation</key>
<value>64</value>
</param>
−
<param>
<key>frequency</key>
<value>tune_osc_dem</value>
</param>
−
<param>
<key>lo_offset</key>
<value>float('inf')</value>
</param>
−
<param>
<key>gain</key>
<value>20</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(162, 521)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>variable_slider</key>
−
<param>
<key>id</key>
<value>fm_freq_mod</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>label</key>
<value>FM frequency modulator</value>
</param>
−
<param>
<key>value</key>
<value>94000000</value>
</param>
−
<param>
<key>min</key>
<value>0</value>
</param>
−
<param>
<key>max</key>
<value>110000000</value>
</param>
−
<param>
<key>num_steps</key>
<value>300</value>
</param>
−
<param>
<key>style</key>
<value>wx.SL_HORIZONTAL</value>
</param>
−
<param>
<key>converver</key>
<value>float_converter</value>
</param>
−
<param>
<key>grid_pos</key>
<value/>
</param>
−
<param>
<key>notebook</key>
<value/>
</param>
−
<param>
<key>_coordinate</key>
<value>(0, 253)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>variable_slider</key>
−
<param>
<key>id</key>
<value>tune_osc_dem</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>label</key>
<value>Tunned frequency demodulator</value>
</param>
−
<param>
<key>value</key>
<value>94000000</value>
</param>
−
<param>
<key>min</key>
<value>88000000</value>
</param>
−
<param>
<key>max</key>
<value>108000000</value>
</param>
−
<param>
<key>num_steps</key>
<value>800</value>
</param>
−
<param>
<key>style</key>
<value>wx.SL_HORIZONTAL</value>
</param>
−
<param>
<key>converver</key>
<value>float_converter</value>
</param>
−
<param>
<key>grid_pos</key>
<value/>
</param>
−
<param>
<key>notebook</key>
<value/>
</param>
−
<param>
<key>_coordinate</key>
<value>(1, 1)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>gr_wavfile_source</key>
−
<param>
<key>id</key>
<value>gr_wavfile_source_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>file</key>
<value>/home/thales/Desktop/outfile2.wav</value>
</param>
−
<param>
<key>repeat</key>
<value>True</value>
</param>
−
<param>
<key>nchan</key>
<value>1</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(223, 186)</value>
</param>
−
<param>
<key>_rotation</key>
<value>180</value>
</param>
</block>
−
<block>
<key>gr_multiply_const_vxx</key>
−
<param>
<key>id</key>
<value>gr_multiply_const_vxx_1</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>type</key>
<value>complex</value>
</param>
−
<param>
<key>const</key>
<value>32000</value>
</param>
−
<param>
<key>vlen</key>
<value>1</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(645, 315)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>blks2_rational_resampler_xxx</key>
−
<param>
<key>id</key>
<value>blks2_rational_resampler_xxx_1_0_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>type</key>
<value>ccc</value>
</param>
−
<param>
<key>decim</key>
<value>25</value>
</param>
−
<param>
<key>interp</key>
<value>32</value>
</param>
−
<param>
<key>taps</key>
<value>[]</value>
</param>
−
<param>
<key>fractional_bw</key>
<value>0</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(371, 467)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>low_pass_filter</key>
−
<param>
<key>id</key>
<value>low_pass_filter_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>type</key>
<value>fir_filter_ccf</value>
</param>
−
<param>
<key>decim</key>
<value>2</value>
</param>
−
<param>
<key>interp</key>
<value>1</value>
</param>
−
<param>
<key>gain</key>
<value>10</value>
</param>
−
<param>
<key>samp_rate</key>
<value>256000</value>
</param>
−
<param>
<key>cutoff_freq</key>
<value>tune_filter</value>
</param>
−
<param>
<key>width</key>
<value>5000</value>
</param>
−
<param>
<key>window</key>
<value>WIN_HAMMING</value>
</param>
−
<param>
<key>beta</key>
<value>6.76</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(583, 443)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>blks2_fm_demod_cf</key>
−
<param>
<key>id</key>
<value>blks2_fm_demod_cf_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>chan_rate</key>
<value>128000</value>
</param>
−
<param>
<key>audio_decim</key>
<value>4</value>
</param>
−
<param>
<key>deviation</key>
<value>75000</value>
</param>
−
<param>
<key>audio_pass</key>
<value>1000</value>
</param>
−
<param>
<key>audio_stop</key>
<value>16000</value>
</param>
−
<param>
<key>gain</key>
<value>20.0</value>
</param>
−
<param>
<key>tau</key>
<value>75e-6</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(784, 443)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>low_pass_filter</key>
−
<param>
<key>id</key>
<value>low_pass_filter_0_0</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>type</key>
<value>interp_fir_filter_fff</value>
</param>
−
<param>
<key>decim</key>
<value>1</value>
</param>
−
<param>
<key>interp</key>
<value>1</value>
</param>
−
<param>
<key>gain</key>
<value>1</value>
</param>
−
<param>
<key>samp_rate</key>
<value>160000</value>
</param>
−
<param>
<key>cutoff_freq</key>
<value>1.5e3</value>
</param>
−
<param>
<key>width</key>
<value>2e3</value>
</param>
−
<param>
<key>window</key>
<value>WIN_HAMMING</value>
</param>
−
<param>
<key>beta</key>
<value>6.76</value>
</param>
−
<param>
<key>_coordinate</key>
<value>(458, 44)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<block>
<key>options</key>
−
<param>
<key>id</key>
<value>top_block</value>
</param>
−
<param>
<key>_enabled</key>
<value>True</value>
</param>
−
<param>
<key>title</key>
<value/>
</param>
−
<param>
<key>author</key>
<value/>
</param>
−
<param>
<key>description</key>
<value/>
</param>
−
<param>
<key>window_size</key>
<value>1280, 1024</value>
</param>
−
<param>
<key>generate_options</key>
<value>wx_gui</value>
</param>
−
<param>
<key>category</key>
<value>Custom</value>
</param>
−
<param>
<key>run</key>
<value>True</value>
</param>
−
<param>
<key>realtime_scheduling</key>
<value/>
</param>
−
<param>
<key>_coordinate</key>
<value>(2, 384)</value>
</param>
−
<param>
<key>_rotation</key>
<value>0</value>
</param>
</block>
−
<connection>
<source_block_id>low_pass_filter_0_0</source_block_id>
<sink_block_id>blks2_rational_resampler_xxx_1</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>blks2_rational_resampler_xxx_0_0</source_block_id>
<sink_block_id>low_pass_filter_0_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>blks2_rational_resampler_xxx_1</source_block_id>
<sink_block_id>gr_frequency_modulator_fc_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>gr_frequency_modulator_fc_0</source_block_id>
<sink_block_id>gr_multiply_const_vxx_1</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>gr_multiply_const_vxx_1</source_block_id>
<sink_block_id>usrp2_sink_xxxx_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>gr_wavfile_source_0</source_block_id>
<sink_block_id>blks2_rational_resampler_xxx_0_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>usrp2_source_xxxx_0</source_block_id>
<sink_block_id>blks2_rational_resampler_xxx_1_0_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>usrp2_source_xxxx_0</source_block_id>
<sink_block_id>wxgui_fftsink2_0_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>blks2_fm_demod_cf_0</source_block_id>
<sink_block_id>audio_sink_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>blks2_rational_resampler_xxx_1_0_0</source_block_id>
<sink_block_id>low_pass_filter_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
−
<connection>
<source_block_id>low_pass_filter_0</source_block_id>
<sink_block_id>blks2_fm_demod_cf_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
</flow_graph>

On 21 September 2010 18:59, Rafael Diniz <address@hidden> wrote:

Hi Jorge,
Can you copy the .grc file you created?

> Hello community!
>
> I initiated myself in GNU radio two weeks ago and I am learning as fast as
> I
> can. To begin with, I decided to play with GRC and my URSP2.
> I successfully built a FM modulator that works fine.
> I successfully built a FM demodulator that works fine.
> But there are still several things I do not understand.
>
> While building the FM modulator:
> 1)Wave file source
> 2)Rational resampler
> 3)LPF
> 4)Rational resampler
> 5)Frequency Mod
> 6)Multiply const
> 7)USRP2 sink
>
> Why is block 6 necessary? I tried with lots of values over 2 and all of
> them
> are ok. I realized that the smaller the number, the higher the noise in my
> receiver (my mobile phone). Is it related to the amplitude of the
> modulated
> signal?
>
> Another thing very strange is that if I create a GRC file with both,
> transmitter and receiver with exactly the same blocks and the same
> parameters I cannot hear any demodulated signal. I can see information
> with
> a FFT block connected to the receiver chain, and I am able to demodulate
> the
> signal with my mobile phone when the example is running but in my computer
> I
> do not hear anything else besides noise mixed with some sort of
> non-understandable signal. Thus, I guess I have to change something in the
> receiver chain although it works alone in my FM demodulator. I changed
> every
> single parameter but I cannot get any improvement.
>
> Any suggestions?
>
> Many thanks in advance,
> Jorge.