1 files changed, 99 insertions, 0 deletions
diff --git a/gnuradio-examples/python/usrp/wfm_rcv_file.py b/gnuradio-examples/python/usrp/wfm_rcv_file.py
new file mode 100755
index 0000000000..2c8d4f7603
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+++ b/gnuradio-examples/python/usrp/wfm_rcv_file.py
@@ -0,0 +1,99 @@
+#!/usr/bin/env python
+
+from gnuradio import gr, eng_notation
+from gnuradio import audio
+# from gnuradio import usrp
+from gnuradio.eng_option import eng_option
+from optparse import OptionParser
+import sys
+import math
+
+
+#
+# return a gr.flow_graph
+#
+def build_graph (input_filename, repeat):
+    adc_rate = 64e6                             # USRP A/D sampling rate
+    decim = 250                                 # FPGA decimated by this amount
+
+    quad_rate = adc_rate / decim                # 256 kHz (the sample rate of the file)
+    audio_decimation = 8
+    audio_rate = quad_rate / audio_decimation   # 32 kHz
+
+    fg = gr.flow_graph ()
+    
+    # usrp is data source
+    # src = usrp.source_c (0, decim)
+    # src.set_rx_freq (0, -IF_freq)
+
+    src = gr.file_source (gr.sizeof_gr_complex, input_filename, repeat)
+    
+    (head, tail) = build_pipeline (fg, quad_rate, audio_decimation)
+
+    # sound card as final sink
+    audio_sink = audio.sink (int (audio_rate))
+
+    # now wire it all together
+    fg.connect (src, head)
+    fg.connect (tail, (audio_sink, 0))
+    
+    return fg
+
+def build_pipeline (fg, quad_rate, audio_decimation):
+    '''Given a flow_graph, fg, construct a pipeline
+    for demodulating a broadcast FM signal.  The
+    input is the downconverteed complex baseband
+    signal. The output is the demodulated audio.
+
+    build_pipeline returns a two element tuple
+    containing the input and output endpoints.
+    '''
+    fm_demod_gain = 2200.0/32768.0
+    audio_rate = quad_rate / audio_decimation
+    volume = 1.0
+
+    # input: complex; output: float
+    fm_demod = gr.quadrature_demod_cf (volume*fm_demod_gain)
+
+    # compute FIR filter taps for audio filter
+    width_of_transition_band = audio_rate / 32
+    audio_coeffs = gr.firdes.low_pass (1.0,            # gain
+                                       quad_rate,      # sampling rate
+                                       audio_rate/2 - width_of_transition_band,
+                                       width_of_transition_band,
+                                       gr.firdes.WIN_HAMMING)
+
+    TAU  = 75e-6  # 75us in US, 50us in EUR
+    fftaps = [ 1 - math.exp(-1/TAU/quad_rate), 0]
+    fbtaps= [ 0 , math.exp(-1/TAU/quad_rate) ]
+    deemph = gr.iir_filter_ffd(fftaps,fbtaps)
+
+    # input: float; output: float
+    audio_filter = gr.fir_filter_fff (audio_decimation, audio_coeffs)
+
+    fg.connect (fm_demod, deemph)
+    fg.connect (deemph, audio_filter)
+    return ((fm_demod, 0), (audio_filter, 0))
+    
+
+def main ():
+    usage = "usage: %prog [options] filename"
+    parser = OptionParser (option_class=eng_option, usage=usage)
+    parser.add_option ("-r", "--repeat", action="store_true", default=False)
+    # parser.add_option (... your stuff here...)
+    (options, args) = parser.parse_args ()
+
+    if len (args) != 1:
+        parser.print_help ()
+        sys.exit (1)
+
+    fg = build_graph (args[0], options.repeat)
+
+    fg.start ()        # fork thread(s) and return
+    raw_input ('Press Enter to quit: ')
+    fg.stop ()
+
+if __name__ == '__main__':
+    main ()
+
+