+++ /dev/null
-#
-# Copyright 2005 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, gru
-
-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_block):
- """
- Uniformly modulated polyphase DFT filter bank: synthesis
-
- See http://cnx.rice.edu/content/m10424/latest
- """
- def __init__(self, fg, mpoints, taps=None):
- """
- Takes M complex streams in, produces single complex stream out
- that runs at M times the input sample rate
-
- @param fg: flow_graph
- @param mpoints: number of freq bins/interpolation factor/subbands
- @param 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
-
- 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 = gr.streams_to_vector(item_size, mpoints)
- self.ifft = gr.fft_vcc(mpoints, False, [])
- self.v2ss = gr.vector_to_streams(item_size, mpoints)
- # mpoints filters go in here...
- self.ss2s = gr.streams_to_stream(item_size, mpoints)
-
- fg.connect(self.ss2v, self.ifft, self.v2ss)
-
- # build mpoints fir filters...
- for i in range(mpoints):
- f = gr.fft_filter_ccc(1, sub_taps[i])
- fg.connect((self.v2ss, i), f)
- fg.connect(f, (self.ss2s, i))
-
- gr.hier_block.__init__(self, fg, self.ss2v, self.ss2s)
-
-
-class analysis_filterbank(gr.hier_block):
- """
- Uniformly modulated polyphase DFT filter bank: analysis
-
- See http://cnx.rice.edu/content/m10424/latest
- """
- def __init__(self, fg, mpoints, taps=None):
- """
- Takes 1 complex stream in, produces M complex streams out
- that runs at 1/M times the input sample rate
-
- @param fg: flow_graph
- @param mpoints: number of freq bins/interpolation factor/subbands
- @param taps: filter taps for subband filter
-
- Same channel to frequency mapping as described above.
- """
- item_size = gr.sizeof_gr_complex
-
- 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 = gr.stream_to_streams(item_size, mpoints)
- # filters here
- self.ss2v = gr.streams_to_vector(item_size, mpoints)
- self.fft = gr.fft_vcc(mpoints, True, [])
- self.v2ss = gr.vector_to_streams(item_size, mpoints)
-
- # build mpoints fir filters...
- for i in range(mpoints):
- f = gr.fft_filter_ccc(1, sub_taps[mpoints-i-1])
- fg.connect((self.s2ss, i), f)
- fg.connect(f, (self.ss2v, i))
-
- fg.connect(self.ss2v, self.fft, self.v2ss)
- gr.hier_block.__init__(self, fg, self.s2ss, self.v2ss)
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