3 # Copyright 2007 Free Software Foundation, Inc.
5 # This file is part of GNU Radio
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)
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.
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.
24 from gnuradio import gr
26 class ofdm_sync(gr.hier_block):
27 def __init__(self, fg, fft_length, cp_length, snr):
30 self.input = gr.add_const_cc(0)
32 SNR = 10.0**(snr/10.0)
33 rho = SNR / (SNR + 1.0)
34 symbol_length = fft_length + cp_length
38 # Energy Detection from ML Sync
41 self.delay = gr.delay(gr.sizeof_gr_complex, fft_length)
42 self.fg.connect(self.input, self.delay)
44 # magnitude squared blocks
45 self.magsqrd1 = gr.complex_to_mag_squared()
46 self.magsqrd2 = gr.complex_to_mag_squared()
47 self.adder = gr.add_ff()
49 moving_sum_taps = [rho/2 for i in range(cp_length)]
50 self.moving_sum_filter = gr.fir_filter_fff(1,moving_sum_taps)
52 self.fg.connect(self.input,self.magsqrd1)
53 self.fg.connect(self.delay,self.magsqrd2)
54 self.fg.connect(self.magsqrd1,(self.adder,0))
55 self.fg.connect(self.magsqrd2,(self.adder,1))
56 self.fg.connect(self.adder,self.moving_sum_filter)
59 # Correlation from ML Sync
60 self.conjg = gr.conjugate_cc();
61 self.mixer = gr.multiply_cc();
63 movingsum2_taps = [1.0 for i in range(cp_length)]
64 self.movingsum2 = gr.fir_filter_ccf(1,movingsum2_taps)
66 # Correlator data handler
67 self.c2mag = gr.complex_to_mag()
68 self.angle = gr.complex_to_arg()
69 self.fg.connect(self.input,(self.mixer,1))
70 self.fg.connect(self.delay,self.conjg,(self.mixer,0))
71 self.fg.connect(self.mixer,self.movingsum2,self.c2mag)
72 self.fg.connect(self.movingsum2,self.angle)
74 # ML Sync output arg, need to find maximum point of this
75 self.diff = gr.sub_ff()
76 self.fg.connect(self.c2mag,(self.diff,0))
77 self.fg.connect(self.moving_sum_filter,(self.diff,1))
79 #ML measurements input to sampler block and detect
80 nco_sensitivity = 1.0/fft_length
81 self.f2c = gr.float_to_complex()
82 self.sampler = gr.ofdm_sampler(fft_length,symbol_length)
83 self.pk_detect = gr.peak_detector_fb(0.2, 0.25, 30, 0.0005)
84 self.sample_and_hold = gr.sample_and_hold_ff()
85 self.nco = gr.frequency_modulator_fc(nco_sensitivity)
86 self.inv = gr.multiply_const_ff(-1)
87 self.sigmix = gr.multiply_cc()
89 # Mix the signal with an NCO controlled by the sync loop
90 self.fg.connect(self.input, (self.sigmix,0))
91 self.fg.connect(self.nco, (self.sigmix,1))
92 self.fg.connect(self.sigmix, (self.sampler,0))
94 # use the sync loop values to set the sampler and the NCO
96 # self.angle = epsilon
98 self.fg.connect(self.diff, self.pk_detect)
103 # Use a fixed trigger point instead of sync block
104 peak_null = gr.null_sink(gr.sizeof_char)
107 peak_trigger = gr.vector_source_b(data, True)
109 self.fg.connect(self.pk_detect, peak_null)
110 self.fg.connect(peak_trigger, (self.sampler,1))
111 self.fg.connect(peak_trigger, (self.sample_and_hold,1))
113 self.dpll = gr.dpll_bb(float(symbol_length),0.01)
115 self.fg.connect(self.pk_detect, self.dpll)
116 self.fg.connect(self.dpll, (self.sampler,1))
117 self.fg.connect(self.dpll, (self.sample_and_hold,1))
119 self.fg.connect(self.pk_detect, (self.sampler,1))
120 self.fg.connect(self.pk_detect, (self.sample_and_hold,1))
122 self.fg.connect(self.angle, (self.sample_and_hold,0))
123 self.fg.connect(self.sample_and_hold, self.inv, self.nco)
126 self.fg.connect(self.diff, gr.file_sink(gr.sizeof_float, "theta_f.dat"))
127 self.fg.connect(self.angle, gr.file_sink(gr.sizeof_float, "epsilon_f.dat"))
129 self.fg.connect(peak_trigger, gr.file_sink(gr.sizeof_char, "peaks_b.dat"))
131 self.fg.connect(self.pk_detect, gr.file_sink(gr.sizeof_char, "peaks_b.dat"))
133 self.fg.connect(self.dpll, gr.file_sink(gr.sizeof_char, "dpll_b.dat"))
135 self.fg.connect(self.sigmix, gr.file_sink(gr.sizeof_gr_complex, "sigmix_c.dat"))
136 self.fg.connect(self.sampler, gr.file_sink(gr.sizeof_gr_complex*fft_length, "sampler_c.dat"))
137 self.fg.connect(self.sample_and_hold, gr.file_sink(gr.sizeof_float, "sample_and_hold_f.dat"))
138 self.fg.connect(self.nco, gr.file_sink(gr.sizeof_gr_complex, "nco_c.dat"))
139 self.fg.connect(self.input, gr.file_sink(gr.sizeof_gr_complex, "input_c.dat"))
141 gr.hier_block.__init__(self, fg, self.input, self.sampler)