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Diffstat (limited to 'gr-analog/python/analog/am_demod.py')
| -rw-r--r-- | gr-analog/python/analog/am_demod.py | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/gr-analog/python/analog/am_demod.py b/gr-analog/python/analog/am_demod.py new file mode 100644 index 0000000000..3459e825f4 --- /dev/null +++ b/gr-analog/python/analog/am_demod.py @@ -0,0 +1,73 @@ +# +# Copyright 2006,2007,2012 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 3, 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., 51 Franklin Street, +# Boston, MA 02110-1301, USA. +# + +from gnuradio import gr +from gnuradio import blocks +from gnuradio import filter + +class am_demod_cf(gr.hier_block2): + """ + Generalized AM demodulation block with audio filtering. + + This block demodulates a band-limited, complex down-converted AM + channel into the the original baseband signal, applying low pass + filtering to the audio output. It produces a float stream in the + range [-1.0, +1.0]. + + Args: + channel_rate: incoming sample rate of the AM baseband (integer) + audio_decim: input to output decimation rate (integer) + audio_pass: audio low pass filter passband frequency (float) + audio_stop: audio low pass filter stop frequency (float) + """ + def __init__(self, channel_rate, audio_decim, audio_pass, audio_stop): + gr.hier_block2.__init__(self, "am_demod_cf", + gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature + gr.io_signature(1, 1, gr.sizeof_float)) # Input signature + + MAG = blocks.complex_to_mag() + DCR = blocks.add_const_ff(-1.0) + + audio_taps = filter.optfir.low_pass(0.5, # Filter gain + channel_rate, # Sample rate + audio_pass, # Audio passband + audio_stop, # Audio stopband + 0.1, # Passband ripple + 60) # Stopband attenuation + LPF = filter.fir_filter_fff(audio_decim, audio_taps) + + self.connect(self, MAG, DCR, LPF, self) + +class demod_10k0a3e_cf(am_demod_cf): + """ + AM demodulation block, 10 KHz channel. + + This block demodulates an AM channel conformant to 10K0A3E emission + standards, such as broadcast band AM transmissions. + + Args: + channel_rate: incoming sample rate of the AM baseband (integer) + audio_decim: input to output decimation rate (integer) + """ + def __init__(self, channel_rate, audio_decim): + am_demod_cf.__init__(self, channel_rate, audio_decim, + 5000, # Audio passband + 5500) # Audio stopband |