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   1 #!/usr/bin/env python
   2 #
   3 # Copyright 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 3, 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 numpy import fft
  25 from gnuradio import gr
  26
  27 class ofdm_sync_pnac(gr.hier_block2):
  28     def __init__(self, fft_length, cp_length, ks):
  29
  30         # FIXME: change the output signature
  31         # should be the output of the divider (the normalized peaks) and
  32         # the angle value out of the sample and hold block
  33         # move sampler out of this block
  34
  35         gr.hier_block2.__init__(self, "ofdm_sync_pnac",
  36                                 gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
  37                                 gr.io_signature(1, 1, gr.sizeof_gr_complex*fft_length)) # Output signature
  38
  39
  40         self.input = gr.add_const_cc(0)
  41
  42         symbol_length = fft_length + cp_length
  43
  44         # PN Sync
  45
  46         # autocorrelate with the known symbol
  47         ks = ks[0:fft_length//2]
  48         ks.reverse()
  49         self.crosscorr_filter = gr.fir_filter_ccc(1, ks)
  50         self.connect(self.crosscorr_filter, gr.file_sink(gr.sizeof_gr_complex, "crosscorr.dat"))
  51
  52         # Create a delay line
  53         self.delay = gr.delay(gr.sizeof_gr_complex, fft_length/2)
  54
  55         # Correlation from ML Sync
  56         self.conjg = gr.conjugate_cc();
  57         self.corr = gr.multiply_cc();
  58
  59         # Create a moving sum filter for the corr output
  60         moving_sum_taps = [1.0 for i in range(fft_length//2)]
  61         self.moving_sum_filter = gr.fir_filter_ccf(1,moving_sum_taps)
  62
  63         # Create a moving sum filter for the input
  64         self.inputmag2 = gr.complex_to_mag_squared()
  65         movingsum2_taps = [1.0 for i in range(fft_length/2)]
  66         self.inputmovingsum = gr.fir_filter_fff(1,movingsum2_taps)
  67         self.square = gr.multiply_ff()
  68         self.normalize = gr.divide_ff()
  69
  70         # Get magnitude (peaks) and angle (phase/freq error)
  71         self.c2mag = gr.complex_to_mag_squared()
  72         self.angle = gr.complex_to_arg()
  73
  74         self.sample_and_hold = gr.sample_and_hold_ff()
  75
  76         # Mix the signal with an NCO controlled by the sync loop
  77         nco_sensitivity = -1.0/fft_length
  78         self.nco = gr.frequency_modulator_fc(nco_sensitivity)
  79         self.sigmix = gr.multiply_cc()
  80
  81         #ML measurements input to sampler block and detect
  82         self.sub1 = gr.add_const_ff(-1)
  83         self.pk_detect = gr.peak_detector_fb(0.2, 0.25, 30, 0.0005)
  84
  85         self.sampler = gr.ofdm_sampler(fft_length,symbol_length)
  86
  87         self.connect(self, self.input)
  88         self.connect(self.input, self.crosscorr_filter)
  89         self.connect(self.crosscorr_filter, self.delay)
  90         self.connect(self.crosscorr_filter, (self.corr,0))
  91         self.connect(self.delay, self.conjg)
  92         self.connect(self.conjg, (self.corr,1))
  93         self.connect(self.corr, self.moving_sum_filter)
  94         self.connect(self.moving_sum_filter, self.c2mag)
  95         self.connect(self.moving_sum_filter, self.angle)
  96         self.connect(self.angle, (self.sample_and_hold,0))
  97         self.connect(self.sample_and_hold, self.nco)
  98
  99         self.connect(self.input, (self.sigmix,0))
 100         self.connect(self.nco, (self.sigmix,1))
 101         self.connect(self.sigmix, (self.sampler,0))
 102
 103         self.connect(self.input, self.inputmag2, self.inputmovingsum)
 104         self.connect(self.inputmovingsum, (self.square,0))
 105         self.connect(self.inputmovingsum, (self.square,1))
 106         self.connect(self.square, (self.normalize,1))
 107         self.connect(self.c2mag, (self.normalize,0))
 108         self.connect(self.normalize, self.sub1, self.pk_detect)
 109
 110         self.connect(self.pk_detect, (self.sampler,1))
 111         self.connect(self.pk_detect, (self.sample_and_hold,1))
 112
 113         self.connect(self.sampler, self)
 114
 115         if 1:
 116             self.connect(self.normalize, gr.file_sink(gr.sizeof_float,
 117                                                       "ofdm_sync_pnac-theta_f.dat"))
 118             self.connect(self.angle, gr.file_sink(gr.sizeof_float,
 119                                                   "ofdm_sync_pnac-epsilon_f.dat"))
 120             self.connect(self.pk_detect, gr.file_sink(gr.sizeof_char,
 121                                                       "ofdm_sync_pnac-peaks_b.dat"))
 122             self.connect(self.sigmix, gr.file_sink(gr.sizeof_gr_complex,
 123                                                    "ofdm_sync_pnac-sigmix_c.dat"))
 124             self.connect(self.sampler, gr.file_sink(gr.sizeof_gr_complex*fft_length,
 125                                                     "ofdm_sync_pnac-sampler_c.dat"))
 126             self.connect(self.sample_and_hold, gr.file_sink(gr.sizeof_float,
 127                                                             "ofdm_sync_pnac-sample_and_hold_f.dat"))
 128             self.connect(self.nco, gr.file_sink(gr.sizeof_gr_complex,
 129                                                 "ofdm_sync_pnac-nco_c.dat"))
 130             self.connect(self.input, gr.file_sink(gr.sizeof_gr_complex,
 131                                                   "ofdm_sync_pnac-input_c.dat"))