diff options
Diffstat (limited to 'gr-uhd/apps/hf_radio/ssbdemod.py')
| -rw-r--r-- | gr-uhd/apps/hf_radio/ssbdemod.py | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/gr-uhd/apps/hf_radio/ssbdemod.py b/gr-uhd/apps/hf_radio/ssbdemod.py new file mode 100644 index 000000000..072d317a2 --- /dev/null +++ b/gr-uhd/apps/hf_radio/ssbdemod.py @@ -0,0 +1,116 @@ +# Copyright 2011 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. +# + +# This tries to push the hilbert transform for ssb demod back into the +# freq. xlating filter. +# +# The starting point for this was weaver_isb_am1_usrp3.py. +# +# The tap coefficients for freq_xlating_fir_filter_ccf were generated +# externally and are read from a file because I didn't want to learn how +# to make fir filters with arbitrary phase response using python numeric +# facilities. +# +# They were generated using Scilab which I am already familiar with. +# M. Revnell Jan 06 + +from gnuradio import gr + +class ssb_demod( gr.hier_block2 ): + def __init__( self, if_rate, af_rate ): + gr.hier_block2.__init__(self, "ssb_demod", + gr.io_signature(1,1,gr.sizeof_gr_complex), + gr.io_signature(1,1,gr.sizeof_float)) + + self.if_rate = int(if_rate) + self.af_rate = int(af_rate) + self.if_decim = int(if_rate / af_rate) + self.sideband = 1 + + self.xlate_taps = ([complex(v) for v in file('ssb_taps').readlines()]) + + self.audio_taps = gr.firdes.low_pass( + 1.0, + self.af_rate, + 3e3, + 600, + gr.firdes.WIN_HAMMING ) + + self.xlate = gr.freq_xlating_fir_filter_ccc( + self.if_decim, + self.xlate_taps, + 0, + self.if_rate ) + + self.split = gr.complex_to_float() + + self.lpf = gr.fir_filter_fff( + 1, self.audio_taps ) + + self.sum = gr.add_ff( ) + self.am_sel = gr.multiply_const_ff( 0 ) + self.sb_sel = gr.multiply_const_ff( 1 ) + self.mixer = gr.add_ff() + self.am_det = gr.complex_to_mag() + + self.connect(self, self.xlate) + self.connect(self.xlate, self.split) + self.connect((self.split, 0), (self.sum, 0)) + self.connect((self.split, 1), (self.sum, 1)) + self.connect(self.sum, self.sb_sel) + self.connect(self.xlate, self.am_det) + self.connect(self.sb_sel, (self.mixer, 0)) + self.connect(self.am_det, self.am_sel) + self.connect(self.am_sel, (self.mixer, 1)) + self.connect(self.mixer, self.lpf) + self.connect(self.lpf, self) + + def upper_sb( self ): + self.xlate.set_taps([v.conjugate() for v in self.xlate_taps]) + self.sb_sel.set_k( 1.0 ) + self.am_sel.set_k( 0.0 ) + + def lower_sb( self ): + self.xlate.set_taps(self.xlate_taps) + self.sb_sel.set_k( 1.0 ) + self.am_sel.set_k( 0.0 ) + + def set_am( self ): + taps = gr.firdes.low_pass( 1.0, + self.if_rate, + 5e3, + 2e3, + gr.firdes.WIN_HAMMING ) + self.xlate.set_taps( taps ) + self.sb_sel.set_k( 0.0 ) + self.am_sel.set_k( 1.0 ) + + def set_bw( self, bw ): + self.audio_taps = gr.firdes.low_pass( + 1.0, + self.af_rate, + bw, + 600, + gr.firdes.WIN_HAMMING ) + self.lpf.set_taps( self.audio_taps ) + + def tune( self, freq ): + self.xlate.set_center_freq( freq ) + |