View source for FM transmission on many channels using gnuradio

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.

==GRC schema==

[[Image:FM transmitter multiple3.png]]

==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)