diff options
| author | jcorgan <jcorgan@221aa14e-8319-0410-a670-987f0aec2ac5> | 2006-10-31 19:15:02 +0000 |
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| committer | jcorgan <jcorgan@221aa14e-8319-0410-a670-987f0aec2ac5> | 2006-10-31 19:15:02 +0000 |
| commit | 50a6df5e198231188f40c23e609a3fe078ad436a (patch) | |
| tree | cfadbb794cd86350adff9461fc2fa9735cb7c640 /gr-pager/src/flex_demod.py | |
| parent | 2c1032480d2874f38af9b5b9d18e753e968619e5 (diff) | |
Restore gr-pager to trunk.
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3909 221aa14e-8319-0410-a670-987f0aec2ac5
Diffstat (limited to 'gr-pager/src/flex_demod.py')
| -rw-r--r-- | gr-pager/src/flex_demod.py | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/gr-pager/src/flex_demod.py b/gr-pager/src/flex_demod.py new file mode 100644 index 0000000000..a8c6f09b13 --- /dev/null +++ b/gr-pager/src/flex_demod.py @@ -0,0 +1,88 @@ +# +# Copyright 2006 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., 51 Franklin Street, +# Boston, MA 02110-1301, USA. +# + +from gnuradio import gr, gru, optfir, blks +from math import pi +import pager_swig + +chan_rate = 16000 + +class flex_demod: + """ + FLEX pager protocol demodulation block. + + This block demodulates a band-limited, complex down-converted baseband + channel into FLEX protocol frames. + + Flow graph (so far): + + RSAMP - Resample incoming stream to 16000 sps + QUAD - Quadrature demodulator converts FSK to baseband amplitudes + LPF - Low pass filter to remove noise prior to slicer + SLICER - Converts input to one of four symbols (0, 1, 2, 3) + SYNC - Converts symbol stream to four phases of FLEX blocks + DEINTx - Deinterleaves FLEX blocks into datawords + PARSEx - Parse a single FLEX phase worth of data words into pages + --- + + @param fg: flowgraph + @param channel_rate: incoming sample rate of the baseband channel + @type sample_rate: integer + """ + + + def __init__(self, fg, channel_rate, queue): + k = chan_rate/(2*pi*4800) # 4800 Hz max deviation + QUAD = gr.quadrature_demod_cf(k) + self.INPUT = QUAD + + if channel_rate != chan_rate: + interp = gru.lcm(channel_rate, chan_rate)/channel_rate + decim = gru.lcm(channel_rate, chan_rate)/chan_rate + RESAMP = blks.rational_resampler_ccf(fg, interp, decim) + self.INPUT = RESAMP + + taps = optfir.low_pass(1.0, chan_rate, 3200, 6400, 0.1, 60) + LPF = gr.fir_filter_fff(1, taps) + SLICER = pager_swig.slicer_fb(.001, .00001) # Attack, decay + SYNC = pager_swig.flex_sync(chan_rate) + + if channel_rate != chan_rate: + fg.connect(RESAMP, QUAD, LPF, SLICER, SYNC) + else: + fg.connect(QUAD, LPF, SLICER, SYNC) + + DEINTA = pager_swig.flex_deinterleave() + PARSEA = pager_swig.flex_parse(queue) + + DEINTB = pager_swig.flex_deinterleave() + PARSEB = pager_swig.flex_parse(queue) + + DEINTC = pager_swig.flex_deinterleave() + PARSEC = pager_swig.flex_parse(queue) + + DEINTD = pager_swig.flex_deinterleave() + PARSED = pager_swig.flex_parse(queue) + + fg.connect((SYNC, 0), DEINTA, PARSEA) + fg.connect((SYNC, 1), DEINTB, PARSEB) + fg.connect((SYNC, 2), DEINTC, PARSEC) + fg.connect((SYNC, 3), DEINTD, PARSED) |