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   1 #!/usr/bin/env python
   2 #
   3 # Copyright 2006, 2007 Free Software Foundation, Inc.
   4 #
   5 # This file is part of GNU Radio
   6 #
   7 # GNU Radio is free software; you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation; either version 2, or (at your option)
  10 # any later version.
  11 #
  12 # GNU Radio is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with GNU Radio; see the file COPYING.  If not, write to
  19 # the Free Software Foundation, Inc., 51 Franklin Street,
  20 # Boston, MA 02110-1301, USA.
  21 #
  22
  23 import math
  24 from gnuradio import gr
  25 from gnuradio.blksimpl.ofdm_sync_ml import ofdm_sync_ml
  26 from gnuradio.blksimpl.ofdm_sync_pn import ofdm_sync_pn
  27 from gnuradio.blksimpl.ofdm_sync_pnac import ofdm_sync_pnac
  28
  29 class ofdm_receiver(gr.hier_block):
  30     def __init__(self, fg, fft_length, cp_length, occupied_tones, snr, ks, logging=False):
  31         self.fg = fg
  32
  33         bw = (float(occupied_tones) / float(fft_length)) / 2.0
  34         tb = bw*0.08
  35         chan_coeffs = gr.firdes.low_pass (1.0,                     # gain
  36                                           1.0,                     # sampling rate
  37                                           bw+tb,                   # midpoint of trans. band
  38                                           tb,                      # width of trans. band
  39                                           gr.firdes.WIN_HAMMING)   # filter type
  40         self.chan_filt = gr.fft_filter_ccc(1, chan_coeffs)
  41
  42         win = [1 for i in range(fft_length)]
  43
  44         SYNC = "pn"
  45         if SYNC == "ml":
  46             self.ofdm_sync = ofdm_sync_ml(fg, fft_length, cp_length, snr, logging)
  47         elif SYNC == "pn":
  48             self.ofdm_sync = ofdm_sync_pn(fg, fft_length, cp_length, logging)
  49         elif SYNC == "pnac":
  50             self.ofdm_sync = ofdm_sync_pnac(fg, fft_length, cp_length, ks[0])
  51
  52         self.fft_demod = gr.fft_vcc(fft_length, True, win, True)
  53         self.ofdm_corr  = gr.ofdm_correlator(occupied_tones, fft_length,
  54                                              cp_length, ks[1], ks[2])
  55
  56         self.fg.connect(self.chan_filt, self.ofdm_sync, self.fft_demod, self.ofdm_corr)
  57
  58         if logging:
  59             self.fg.connect(self.chan_filt, gr.file_sink(gr.sizeof_gr_complex, "chan_filt_c.dat"))
  60             self.fg.connect(self.fft_demod, gr.file_sink(gr.sizeof_gr_complex*fft_length, "fft_out_c.dat"))
  61             self.fg.connect(self.ofdm_corr, gr.file_sink(gr.sizeof_gr_complex*occupied_tones, "ofdm_corr_out_c.dat"))
  62             self.fg.connect((self.ofdm_corr,1), gr.file_sink(1, "found_corr_b.dat"))
  63
  64         gr.hier_block.__init__(self, fg, self.chan_filt, self.ofdm_corr)