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Diffstat (limited to 'gnuradio-examples/python/mc4020/fm_demod.py')
| -rwxr-xr-x | gnuradio-examples/python/mc4020/fm_demod.py | 150 |
1 files changed, 0 insertions, 150 deletions
diff --git a/gnuradio-examples/python/mc4020/fm_demod.py b/gnuradio-examples/python/mc4020/fm_demod.py deleted file mode 100755 index e58407f738..0000000000 --- a/gnuradio-examples/python/mc4020/fm_demod.py +++ /dev/null @@ -1,150 +0,0 @@ -#!/usr/bin/env python - -from gnuradio import gr -from gnuradio import audio -from gnuradio import mc4020 -import sys - -def high_speed_adc (fg, input_rate): - # return gr.file_source (gr.sizeof_short, "dummy.dat", False) - return mc4020.source (input_rate, mc4020.MCC_CH3_EN | mc4020.MCC_ALL_1V) - -# -# return a gr.flow_graph -# -def build_graph (freq1, freq2): - input_rate = 20e6 - cfir_decimation = 125 - audio_decimation = 5 - - quad_rate = input_rate / cfir_decimation - audio_rate = quad_rate / audio_decimation - - fg = gr.flow_graph () - - # use high speed ADC as input source - src = high_speed_adc (fg, input_rate) - - # compute FIR filter taps for channel selection - channel_coeffs = \ - gr.firdes.low_pass (1.0, # gain - input_rate, # sampling rate - 250e3, # low pass cutoff freq - 8*100e3, # width of trans. band - gr.firdes.WIN_HAMMING) - - # input: short; output: complex - chan_filter1 = \ - gr.freq_xlating_fir_filter_scf (cfir_decimation, - channel_coeffs, - freq1, # 1st station freq - input_rate) - - (head1, tail1) = 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, chan_filter1) - fg.connect (chan_filter1, head1) - fg.connect (tail1, (audio_sink, 0)) - - # two stations at once? - if freq2: - # Extract the second station and connect - # it to a second pipeline... - - # input: short; output: complex - chan_filter2 = \ - gr.freq_xlating_fir_filter_scf (cfir_decimation, - channel_coeffs, - freq2, # 2nd station freq - input_rate) - - (head2, tail2) = build_pipeline (fg, quad_rate, audio_decimation) - - fg.connect (src, chan_filter2) - fg.connect (chan_filter2, head2) - fg.connect (tail2, (audio_sink, 1)) - - 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) - - # input: float; output: float - audio_filter = gr.fir_filter_fff (audio_decimation, audio_coeffs) - - fg.connect (fm_demod, audio_filter) - return ((fm_demod, 0), (audio_filter, 0)) - - -def main (args): - nargs = len (args) - if nargs == 1: - freq1 = float (args[0]) * 1e6 - freq2 = None - elif nargs == 2: - freq1 = float (args[0]) * 1e6 - freq2 = float (args[1]) * 1e6 - else: - sys.stderr.write ('usage: fm_demod freq1 [freq2]\n') - sys.exit (1) - - # connect to RF front end - rf_front_end = gr.microtune_4937_eval_board () - if not rf_front_end.board_present_p (): - raise IOError, 'RF front end not found' - - # set front end gain - rf_front_end.set_AGC (300) - IF_freq = rf_front_end.get_output_freq () - IF_freq = 5.75e6 - - if not freq2: # one station - - rf_front_end.set_RF_freq (freq1) - fg = build_graph (IF_freq, None) - - else: # two stations - - if abs (freq1 - freq2) > 5.5e6: - raise IOError, 'freqs too far apart' - - target_freq = (freq1 + freq2) / 2 - actual_freq = rf_front_end.set_RF_freq (target_freq) - #actual_freq = target_freq - - fg = build_graph (IF_freq + freq1 - actual_freq, - IF_freq + freq2 - actual_freq) - - fg.start () # fork thread(s) and return - raw_input ('Press Enter to quit: ') - fg.stop () - -if __name__ == '__main__': - main (sys.argv[1:]) - - |