diff options
| author | Tom Rondeau <trondeau@vt.edu> | 2012-12-21 15:11:39 -0500 |
|---|---|---|
| committer | Tom Rondeau <trondeau@vt.edu> | 2012-12-21 21:19:13 -0500 |
| commit | 55d3e4a47958be287648a2021f7e92d81086b2d9 (patch) | |
| tree | ae0195c457f2cf2734376679cc88c2d728040680 /gr-filter/python/filterbank.py | |
| parent | fa781237f341a74a243a9fb930daee7e62c3a682 (diff) | |
blocks: removes blocks moved to gr-blocks from gnuradio-core.
Also fixes up some other missing moves.
Diffstat (limited to 'gr-filter/python/filterbank.py')
| -rw-r--r-- | gr-filter/python/filterbank.py | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/gr-filter/python/filterbank.py b/gr-filter/python/filterbank.py new file mode 100644 index 0000000000..a8ee27ce97 --- /dev/null +++ b/gr-filter/python/filterbank.py @@ -0,0 +1,173 @@ +# +# Copyright 2005,2007 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. +# + +import sys +from gnuradio import gr +from gnuradio import fft +from gnuradio import blocks + +def _generate_synthesis_taps(mpoints): + return [] # FIXME + + +def _split_taps(taps, mpoints): + assert (len(taps) % mpoints) == 0 + result = [list() for x in range(mpoints)] + for i in xrange(len(taps)): + (result[i % mpoints]).append(taps[i]) + return [tuple(x) for x in result] + + +class synthesis_filterbank(gr.hier_block2): + """ + Uniformly modulated polyphase DFT filter bank: synthesis + + See http://cnx.org/content/m10424/latest + """ + def __init__(self, mpoints, taps=None): + """ + Takes M complex streams in, produces single complex stream out + that runs at M times the input sample rate + + Args: + mpoints: number of freq bins/interpolation factor/subbands + taps: filter taps for subband filter + + The channel spacing is equal to the input sample rate. + The total bandwidth and output sample rate are equal the input + sample rate * nchannels. + + Output stream to frequency mapping: + + channel zero is at zero frequency. + + if mpoints is odd: + + Channels with increasing positive frequencies come from + channels 1 through (N-1)/2. + + Channel (N+1)/2 is the maximum negative frequency, and + frequency increases through N-1 which is one channel lower + than the zero frequency. + + if mpoints is even: + + Channels with increasing positive frequencies come from + channels 1 through (N/2)-1. + + Channel (N/2) is evenly split between the max positive and + negative bins. + + Channel (N/2)+1 is the maximum negative frequency, and + frequency increases through N-1 which is one channel lower + than the zero frequency. + + Channels near the frequency extremes end up getting cut + off by subsequent filters and therefore have diminished + utility. + """ + item_size = gr.sizeof_gr_complex + gr.hier_block2.__init__(self, "synthesis_filterbank", + gr.io_signature(mpoints, mpoints, item_size), # Input signature + gr.io_signature(1, 1, item_size)) # Output signature + + + if taps is None: + taps = _generate_synthesis_taps(mpoints) + + # pad taps to multiple of mpoints + r = len(taps) % mpoints + if r != 0: + taps = taps + (mpoints - r) * (0,) + + # split in mpoints separate set of taps + sub_taps = _split_taps(taps, mpoints) + + self.ss2v = blocks.streams_to_vector(item_size, mpoints) + self.ifft = fft.fft_vcc(mpoints, False, []) + self.v2ss = blocks.vector_to_streams(item_size, mpoints) + # mpoints filters go in here... + self.ss2s = blocks.streams_to_stream(item_size, mpoints) + + for i in range(mpoints): + self.connect((self, i), (self.ss2v, i)) + + self.connect(self.ss2v, self.ifft, self.v2ss) + + # build mpoints fir filters... + for i in range(mpoints): + f = fft.fft_filter_ccc(1, sub_taps[i]) + self.connect((self.v2ss, i), f) + self.connect(f, (self.ss2s, i)) + + self.connect(self.ss2s, self) + +class analysis_filterbank(gr.hier_block2): + """ + Uniformly modulated polyphase DFT filter bank: analysis + + See http://cnx.org/content/m10424/latest + """ + def __init__(self, mpoints, taps=None): + """ + Takes 1 complex stream in, produces M complex streams out + that runs at 1/M times the input sample rate + + Args: + mpoints: number of freq bins/interpolation factor/subbands + taps: filter taps for subband filter + + Same channel to frequency mapping as described above. + """ + item_size = gr.sizeof_gr_complex + gr.hier_block2.__init__(self, "analysis_filterbank", + gr.io_signature(1, 1, item_size), # Input signature + gr.io_signature(mpoints, mpoints, item_size)) # Output signature + + if taps is None: + taps = _generate_synthesis_taps(mpoints) + + # pad taps to multiple of mpoints + r = len(taps) % mpoints + if r != 0: + taps = taps + (mpoints - r) * (0,) + + # split in mpoints separate set of taps + sub_taps = _split_taps(taps, mpoints) + + # print >> sys.stderr, "mpoints =", mpoints, "len(sub_taps) =", len(sub_taps) + + self.s2ss = blocks.stream_to_streams(item_size, mpoints) + # filters here + self.ss2v = blocks.streams_to_vector(item_size, mpoints) + self.fft = fft.fft_vcc(mpoints, True, []) + self.v2ss = blocks.vector_to_streams(item_size, mpoints) + + self.connect(self, self.s2ss) + + # build mpoints fir filters... + for i in range(mpoints): + f = fft.fft_filter_ccc(1, sub_taps[mpoints-i-1]) + self.connect((self.s2ss, i), f) + self.connect(f, (self.ss2v, i)) + self.connect((self.v2ss, i), (self, i)) + + self.connect(self.ss2v, self.fft, self.v2ss) |