FM transmission on many channels using gnuradio
From Opendigitalradio
FM transmitter on many channels using gnuradio.
Tools needed:
- gnuradio 3.2
- grc (gnuradio companion)
- mpg123
- USRP
In this example we will show how to make an FM software transmitter broadcasting simultaneously on many channels.
Look at GRC schema or use directly python code below.
Python code
#!/usr/bin/env python ################################################## # Gnuradio Python Flow Graph # Title: Multiplex frequencies FM transmitter # Author: Mathias Coinchon # Generated: Sat Jan 2 19:19:17 2010 ################################################## from gnuradio import blks2 from gnuradio import gr from gnuradio.eng_option import eng_option from gnuradio.gr import firdes from gnuradio.wxgui import fftsink2 from gnuradio.wxgui import forms from grc_gnuradio import usrp as grc_usrp from grc_gnuradio import wxgui as grc_wxgui from optparse import OptionParser import wx class MF_FM_TX(grc_wxgui.top_block_gui): def __init__(self): grc_wxgui.top_block_gui.__init__(self, title="Multiplex frequencies FM transmitter") ################################################## # Variables ################################################## self.samp_rate = samp_rate = 32000 self.quad_rate = quad_rate = 1280000 self.carrier2_frequency = carrier2_frequency = 300000 self.carrier1_frequency = carrier1_frequency = -300000 self.FM_frequency = FM_frequency = 107600000 ################################################## # Controls ################################################## _carrier2_frequency_sizer = wx.BoxSizer(wx.VERTICAL) self._carrier2_frequency_text_box = forms.text_box( parent=self.GetWin(), sizer=_carrier2_frequency_sizer, value=self.carrier2_frequency, callback=self.set_carrier2_frequency, label="Carrier 2 Frequency", converter=forms.float_converter(), proportion=0, ) self._carrier2_frequency_slider = forms.slider( parent=self.GetWin(), sizer=_carrier2_frequency_sizer, value=self.carrier2_frequency, callback=self.set_carrier2_frequency, minimum=-500000, maximum=500000, num_steps=100, style=wx.SL_HORIZONTAL, cast=float, proportion=1, ) self.Add(_carrier2_frequency_sizer) _carrier1_frequency_sizer = wx.BoxSizer(wx.VERTICAL) self._carrier1_frequency_text_box = forms.text_box( parent=self.GetWin(), sizer=_carrier1_frequency_sizer, value=self.carrier1_frequency, callback=self.set_carrier1_frequency, label="Carrier 1 Frequency", converter=forms.float_converter(), proportion=0, ) self._carrier1_frequency_slider = forms.slider( parent=self.GetWin(), sizer=_carrier1_frequency_sizer, value=self.carrier1_frequency, callback=self.set_carrier1_frequency, minimum=-500000, maximum=500000, num_steps=100, style=wx.SL_HORIZONTAL, cast=float, proportion=1, ) self.Add(_carrier1_frequency_sizer) _FM_frequency_sizer = wx.BoxSizer(wx.VERTICAL) self._FM_frequency_text_box = forms.text_box( parent=self.GetWin(), sizer=_FM_frequency_sizer, value=self.FM_frequency, callback=self.set_FM_frequency, label="Central FM frequency", converter=forms.float_converter(), proportion=0, ) self._FM_frequency_slider = forms.slider( parent=self.GetWin(), sizer=_FM_frequency_sizer, value=self.FM_frequency, callback=self.set_FM_frequency, minimum=87500000, maximum=108000000, num_steps=205, style=wx.SL_HORIZONTAL, cast=float, proportion=1, ) self.Add(_FM_frequency_sizer) ################################################## # Blocks ################################################## self.blks2_rational_resampler_xxx_0 = blks2.rational_resampler_ccc( interpolation=4, decimation=1, taps=None, fractional_bw=None, ) self.blks2_wfm_tx_0 = blks2.wfm_tx( audio_rate=samp_rate, quad_rate=320000, tau=50e-6, max_dev=75e3, ) self.gr_add_xx_0 = gr.add_vcc(1) self.gr_multiply_const_vxx_0 = gr.multiply_const_vcc((5000, )) self.gr_multiply_xx_0 = gr.multiply_vcc(1) self.gr_multiply_xx_1 = gr.multiply_vcc(1) self.gr_sig_source_x_0 = gr.sig_source_c(quad_rate, gr.GR_COS_WAVE, carrier1_frequency, 1, 0) self.gr_sig_source_x_1 = gr.sig_source_c(quad_rate, gr.GR_COS_WAVE, carrier2_frequency, 1, 0) self.gr_wavfile_source_0 = gr.wavfile_source("/home/mc/FM_demo/test_32k_mono.wav", True) self.usrp_simple_sink_x_0 = grc_usrp.simple_sink_c(which=0, side="B") self.usrp_simple_sink_x_0.set_interp_rate(100) self.usrp_simple_sink_x_0.set_frequency(-FM_frequency, verbose=True) self.usrp_simple_sink_x_0.set_gain(0) self.wxgui_fftsink2_0 = fftsink2.fft_sink_c( self.GetWin(), baseband_freq=0, y_per_div=10, y_divs=10, ref_level=50, sample_rate=quad_rate, fft_size=1024, fft_rate=30, average=False, avg_alpha=None, title="FFT Plot", peak_hold=False, ) self.Add(self.wxgui_fftsink2_0.win) ################################################## # Connections ################################################## self.connect((self.gr_wavfile_source_0, 0), (self.blks2_wfm_tx_0, 0)) self.connect((self.gr_multiply_const_vxx_0, 0), (self.usrp_simple_sink_x_0, 0)) self.connect((self.gr_multiply_xx_0, 0), (self.gr_add_xx_0, 0)) self.connect((self.gr_add_xx_0, 0), (self.gr_multiply_const_vxx_0, 0)) self.connect((self.gr_add_xx_0, 0), (self.wxgui_fftsink2_0, 0)) self.connect((self.blks2_wfm_tx_0, 0), (self.blks2_rational_resampler_xxx_0, 0)) self.connect((self.blks2_rational_resampler_xxx_0, 0), (self.gr_add_xx_0, 1)) self.connect((self.gr_multiply_xx_1, 0), (self.gr_add_xx_0, 2)) self.connect((self.gr_sig_source_x_1, 0), (self.gr_multiply_xx_1, 1)) self.connect((self.blks2_rational_resampler_xxx_0, 0), (self.gr_multiply_xx_1, 0)) self.connect((self.blks2_rational_resampler_xxx_0, 0), (self.gr_multiply_xx_0, 1)) self.connect((self.gr_sig_source_x_0, 0), (self.gr_multiply_xx_0, 0)) def set_samp_rate(self, samp_rate): self.samp_rate = samp_rate def set_quad_rate(self, quad_rate): self.quad_rate = quad_rate self.wxgui_fftsink2_0.set_sample_rate(self.quad_rate) self.gr_sig_source_x_1.set_sampling_freq(self.quad_rate) self.gr_sig_source_x_0.set_sampling_freq(self.quad_rate) def set_carrier2_frequency(self, carrier2_frequency): self.carrier2_frequency = carrier2_frequency self._carrier2_frequency_slider.set_value(self.carrier2_frequency) self._carrier2_frequency_text_box.set_value(self.carrier2_frequency) self.gr_sig_source_x_1.set_frequency(self.carrier2_frequency) def set_carrier1_frequency(self, carrier1_frequency): self.carrier1_frequency = carrier1_frequency self._carrier1_frequency_slider.set_value(self.carrier1_frequency) self._carrier1_frequency_text_box.set_value(self.carrier1_frequency) self.gr_sig_source_x_0.set_frequency(self.carrier1_frequency) def set_FM_frequency(self, FM_frequency): self.FM_frequency = FM_frequency self._FM_frequency_slider.set_value(self.FM_frequency) self._FM_frequency_text_box.set_value(self.FM_frequency) self.usrp_simple_sink_x_0.set_frequency(-self.FM_frequency) if __name__ == '__main__': parser = OptionParser(option_class=eng_option, usage="%prog: [options]") (options, args) = parser.parse_args() tb = MF_FM_TX() tb.Run(True)