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#!/usr/bin/env python
#
# Copyright 2004 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# GNU Radio is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.
#
#
# Demodulate an AM signal from the TVRX or a recorded file.
# The file format must be 256 ksps, complex data.
#
from gnuradio import gr, gru, eng_notation
from gnuradio import audio_oss as audio
from gnuradio import usrp
from gnuradio import tv_rx
from gnuradio.eng_option import eng_option
from optparse import OptionParser
import sys
import math
from gnuradio.wxgui import stdgui, fftsink, scopesink
import wx
#
# return a gr.flow_graph
#
class wfm_rx_graph (stdgui.gui_flow_graph):
def __init__(self,frame,panel,vbox,argv):
stdgui.gui_flow_graph.__init__ (self,frame,panel,vbox,argv)
#set rf freq
rf_freq = 120.e6
# Decimation rate from USRP ADC to IF.
usrp_decim = 100
# Calculate the sampling rate of the USRP and capture file.
# Decimate the IF sampling rate down by 4 to 64 ksps
# This is a flow graph that has an input (capture file) and output (audio channel).
#self = gr.flow_graph ()
# Signal source is assumed to be 256 kspb / complex data stream.
which_side = 0
# usrp is data source
if which_side == 0:
src = usrp.source_c (0, usrp_decim, 1, gru.hexint(0xf0f0f0f0), 0)
else:
src = usrp.source_c (0, usrp_decim, 1, gru.hexint(0xf0f0f0f2), 0)
if_rate = 640e3 # src.adc_freq() / usrp_decim
if_decim = 5
demod_rate = if_rate / if_decim
audio_decimation = 4
audio_rate = demod_rate / audio_decimation
# set up frontend
dboard = tv_rx.tv_rx (src, which_side)
self.dboard = dboard
(success, actual_freq) = dboard.set_freq(rf_freq)
assert success
if_freq = rf_freq - actual_freq
src.set_rx_freq (0, -if_freq)
print "actual freq ", actual_freq
print "IF freq ", if_freq
dboard.set_gain(50)
#src = gr.file_source (gr.sizeof_gr_complex, "samples/atis_ffz_am_baseband_256k_complex.dat")
#src = gr.file_source (gr.sizeof_gr_complex, "samples/garagedoor1.dat", True)
#channel_coeffs = gr.firdes.band_pass (
# 1.0, # gain
# if_rate,
# 10, # center of low transition band
# 10000, # center of hi transition band
# 200, # width of transition band
# gr.firdes.WIN_HAMMING)
channel_coeffs = gr.firdes.low_pass (1.0, if_rate, 10e3, 4e3, gr.firdes.WIN_HANN)
print "len(channel_coeffs) = ", len(channel_coeffs)
# Tune to the desired frequency.
ddc = gr.freq_xlating_fir_filter_ccf (if_decim, channel_coeffs, -20e3, if_rate)
# Demodule with classic sqrt (I*I + Q*Q)
magblock = gr.complex_to_mag()
# Scale the audio
volumecontrol = gr.multiply_const_ff(.1)
#band-pass
audio_coeffs = gr.firdes.band_pass (
1.0, # gain
demod_rate,
10, # center of low transition band
6000, # center of hi transition band
200, # width of transition band
gr.firdes.WIN_HAMMING)
# Low pass filter the demodulator output
#audio_coeffs = gr.firdes.low_pass (1.0, demod_rate, 500, 200, gr.firdes.WIN_HANN)
print "len(audio_coeffs) = ", len(audio_coeffs)
# input: float; output: float
audio_filter = gr.fir_filter_fff (audio_decimation, audio_coeffs)
# sound card as final sink
audio_sink = audio.sink (int (audio_rate))
# now wire it all together
self.connect (src, ddc)
self.connect (ddc, magblock)
self.connect (magblock, volumecontrol)
self.connect (volumecontrol, audio_filter)
self.connect (audio_filter, (audio_sink, 0))
d_win = fftsink.fft_sink_c (self, panel, title="RF", fft_size=512, sample_rate=if_rate)
self.connect (src,d_win)
vbox.Add (d_win.win, 4, wx.EXPAND)
p_win = fftsink.fft_sink_c (self, panel, title="IF", fft_size=512, sample_rate=demod_rate)
self.connect (ddc,p_win)
vbox.Add (p_win.win, 4, wx.EXPAND)
r_win = fftsink.fft_sink_f (self, panel, title="Audio", fft_size=512, sample_rate=audio_rate)
self.connect (audio_filter,r_win)
vbox.Add (r_win.win, 4, wx.EXPAND)
#audio_oscope = scopesink.scope_sink_f (self, panel, "Oscope Data", audio_rate)
#self.connect (audio_filter, audio_oscope)
#vbox.Add (audio_oscope.win, 4, wx.EXPAND)
if __name__ == '__main__':
app = stdgui.stdapp (wfm_rx_graph, "TVRX AM RX")
app.MainLoop ()
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