1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
|
#!/usr/bin/env python
#
# Copyright 2008 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.
#
# the code in this file is partially adapted from ofdm.py from the gnuradio
# trunk (actually, only frequency synchronisation is done the same way, as that
# implementation otherwise is not suited for DAB)
#
# Andreas Mueller, 2008
# andrmuel@ee.ethz.ch
from gnuradio import gr, blocks, fft, filter, digital
import gnuradio.dab as grdab
from threading import Timer
from time import sleep
from math import pi
"""
modulator and demodulator for the DAB physical layer
"""
class ofdm_mod(gr.hier_block2):
"""
@brief Block to create a DAB signal from bits.
Takes a data stream and performs OFDM modulation according to the DAB standard.
The output sample rate is 2.048 MSPS.
"""
def __init__(self, dab_params, verbose=False, debug=False):
"""
Hierarchical block for OFDM modulation
@param dab_params DAB parameter object (grdab.parameters.dab_parameters)
@param debug enables debug output to files
"""
dp = dab_params
gr.hier_block2.__init__(self,"ofdm_mod",
gr.io_signature2(2, 2, gr.sizeof_char*dp.num_carriers/4, gr.sizeof_char), # input signature
gr.io_signature (1, 1, gr.sizeof_gr_complex)) # output signature
# symbol mapping
self.mapper_v2s = blocks.vector_to_stream(gr.sizeof_char, 384)
self.mapper_unpack = blocks.packed_to_unpacked_bb(1, gr.GR_MSB_FIRST)
self.mapper = grdab.mapper_bc(dp.num_carriers)
self.mapper_s2v = blocks.stream_to_vector(gr.sizeof_gr_complex, 1536)
# add pilot symbol
self.insert_pilot = grdab.ofdm_insert_pilot_vcc(dp.prn)
# phase sum
self.sum_phase = grdab.sum_phasor_trig_vcc(dp.num_carriers)
# frequency interleaving
self.interleave = grdab.frequency_interleaver_vcc(dp.frequency_interleaving_sequence_array)
# add central carrier & move to middle
self.move_and_insert_carrier = grdab.ofdm_move_and_insert_zero(dp.fft_length, dp.num_carriers)
# ifft
self.ifft = fft.fft_vcc(dp.fft_length, False, [], True)
# cyclic prefixer
self.prefixer = digital.ofdm_cyclic_prefixer(dp.fft_length, dp.symbol_length)
# convert back to vectors
self.s2v = blocks.stream_to_vector(gr.sizeof_gr_complex, dp.symbol_length)
# add null symbol
self.insert_null = grdab.insert_null_symbol(dp.ns_length, dp.symbol_length)
#
# connect it all
#
# data
self.connect((self,0), self.mapper_v2s, self.mapper_unpack, self.mapper, self.mapper_s2v, (self.insert_pilot,0), (self.sum_phase,0), self.interleave, self.move_and_insert_carrier, self.ifft, self.prefixer, self.s2v, (self.insert_null,0))
self.connect(self.insert_null, self)
# control signal (frame start)
self.connect((self,1), (self.insert_pilot,1), (self.sum_phase,1), (self.insert_null,1))
if debug:
#self.connect(self.mapper, blocks.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/generated_signal_mapper.dat"))
self.connect(self.insert_pilot, blocks.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/generated_signal_insert_pilot.dat"))
self.connect(self.sum_phase, blocks.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/generated_signal_sum_phase.dat"))
self.connect(self.interleave, blocks.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/generated_signal_interleave.dat"))
self.connect(self.move_and_insert_carrier, blocks.file_sink(gr.sizeof_gr_complex*dp.fft_length, "debug/generated_signal_move_and_insert_carrier.dat"))
self.connect(self.ifft, blocks.file_sink(gr.sizeof_gr_complex*dp.fft_length, "debug/generated_signal_ifft.dat"))
self.connect(self.prefixer, blocks.file_sink(gr.sizeof_gr_complex, "debug/generated_signal_prefixer.dat"))
self.connect(self.insert_null, blocks.file_sink(gr.sizeof_gr_complex, "debug/generated_signal.dat"))
class ofdm_demod(gr.hier_block2):
"""
@brief Block to demodulate a DAB signal into bits.
Takes a stream of complex baseband samples and performs OFDM demodulation according to the DAB standard.
Expects an input sample rate of 2.048 MSPS.
"""
def __init__(self, dab_params, rx_params, verbose=False, debug=False):
"""
Hierarchical block for OFDM demodulation
@param dab_params DAB parameter object (grdab.parameters.dab_parameters)
@param rx_params RX parameter object (grdab.parameters.receiver_parameters)
@param debug enables debug output to files
@param verbose whether to produce verbose messages
"""
self.dp = dp = dab_params
self.rp = rp = rx_params
self.verbose = verbose
if self.rp.softbits:
gr.hier_block2.__init__(self,"ofdm_demod",
gr.io_signature (1, 1, gr.sizeof_gr_complex), # input signature
gr.io_signature (1, 1, gr.sizeof_float*self.dp.num_carriers*2)) # output signature
else:
gr.hier_block2.__init__(self,"ofdm_demod",
gr.io_signature (1, 1, gr.sizeof_gr_complex), # input signature
gr.io_signature (1, 1, gr.sizeof_char*self.dp.num_carriers/4)) # output signature
# workaround for a problem that prevents connecting more than one block directly (see trac ticket #161)
#self.input = gr.kludge_copy(gr.sizeof_gr_complex)
self.input = blocks.multiply_const_cc(1.0) # FIXME
self.connect(self, self.input)
# input filtering
if self.rp.input_fft_filter:
if verbose: print("--> RX filter enabled")
lowpass_taps = filter.firdes.low_pass(1.0, # gain
dp.sample_rate, # sampling rate
rp.filt_bw, # cutoff frequency
rp.filt_tb, # width of transition band
fft.window.WIN_HAMMING) # Hamming window
self.fft_filter = filter.fft_filter_ccc(1, lowpass_taps)
# correct sample rate offset, if enabled
if self.rp.autocorrect_sample_rate:
if verbose: print("--> dynamic sample rate correction enabled")
self.rate_detect_ns = grdab.detect_null(dp.ns_length, False)
self.rate_estimator = grdab.estimate_sample_rate_bf(dp.sample_rate, dp.frame_length)
self.rate_prober = blocks.probe_signal_f()
self.connect(self.input, self.rate_detect_ns, self.rate_estimator, self.rate_prober)
# self.resample = gr.fractional_interpolator_cc(0, 1)
self.resample = grdab.fractional_interpolator_triggered_update_cc(0,1)
self.connect(self.rate_detect_ns, (self.resample,1))
self.updater = Timer(0.1,self.update_correction)
# self.updater = threading.Thread(target=self.update_correction)
self.run_interpolater_update_thread = True
self.updater.setDaemon(True)
self.updater.start()
else:
self.run_interpolater_update_thread = False
if self.rp.sample_rate_correction_factor != 1 or self.rp.always_include_resample:
if verbose: print("--> static sample rate correction enabled")
self.resample = filter.mmse_resampler_cc(0, self.rp.sample_rate_correction_factor)
# timing and fine frequency synchronisation
self.sync = grdab.ofdm_sync_dab2(self.dp, self.rp, debug)
# ofdm symbol sampler
self.sampler = grdab.ofdm_sampler(dp.fft_length, dp.cp_length, dp.symbols_per_frame, rp.cp_gap)
# fft for symbol vectors
self.fft = fft.fft_vcc(dp.fft_length, True, [], True)
# coarse frequency synchronisation
self.cfs = grdab.ofdm_coarse_frequency_correct(dp.fft_length, dp.num_carriers, dp.cp_length)
# diff phasor
self.phase_diff = grdab.diff_phasor_vcc(dp.num_carriers)
# remove pilot symbol
self.remove_pilot = grdab.ofdm_remove_first_symbol_vcc(dp.num_carriers)
# magnitude equalisation
if self.rp.equalize_magnitude:
if verbose: print("--> magnitude equalization enabled")
self.equalizer = grdab.magnitude_equalizer_vcc(dp.num_carriers, rp.symbols_for_magnitude_equalization)
# frequency deinterleaving
self.deinterleave = grdab.frequency_interleaver_vcc(dp.frequency_deinterleaving_sequence_array)
# symbol demapping
self.demapper = grdab.qpsk_demapper_vcb(dp.num_carriers)
#
# connect everything
#
if self.rp.autocorrect_sample_rate or self.rp.sample_rate_correction_factor != 1 or self.rp.always_include_resample:
self.connect(self.input, self.resample)
self.input2 = self.resample
else:
self.input2 = self.input
if self.rp.input_fft_filter:
self.connect(self.input2, self.fft_filter, self.sync)
else:
self.connect(self.input2, self.sync)
# data stream
self.connect(self.sync, self.sampler, self.fft, self.cfs, self.phase_diff, self.remove_pilot)
if self.rp.equalize_magnitude:
self.connect(self.remove_pilot, self.equalizer, self.deinterleave)
else:
self.connect(self.remove_pilot, self.deinterleave)
if self.rp.softbits:
if verbose: print("--> using soft bits")
self.softbit_interleaver = grdab.complex_to_interleaved_float_vcf(self.dp.num_carriers)
self.connect(self.deinterleave, self.softbit_interleaver, (self,0))
else:
self.connect(self.deinterleave, self.demapper, (self,0))
# calculate an estimate of the SNR
self.phase_var_decim = blocks.keep_one_in_n(gr.sizeof_gr_complex*self.dp.num_carriers, self.rp.phase_var_estimate_downsample)
self.phase_var_arg = blocks.complex_to_arg(dp.num_carriers)
self.phase_var_v2s = blocks.vector_to_stream(gr.sizeof_float, dp.num_carriers)
self.phase_var_mod = grdab.modulo_ff(pi/2)
self.phase_var_avg_mod = filter.iir_filter_ffd([rp.phase_var_estimate_alpha], [0,1-rp.phase_var_estimate_alpha])
self.phase_var_sub_avg = blocks.sub_ff()
self.phase_var_sqr = blocks.multiply_ff()
self.phase_var_avg = filter.iir_filter_ffd([rp.phase_var_estimate_alpha], [0,1-rp.phase_var_estimate_alpha])
self.probe_phase_var = blocks.probe_signal_f()
self.connect((self.remove_pilot,0), self.phase_var_decim, self.phase_var_arg, self.phase_var_v2s, self.phase_var_mod, (self.phase_var_sub_avg,0), (self.phase_var_sqr,0))
self.connect(self.phase_var_mod, self.phase_var_avg_mod, (self.phase_var_sub_avg,1))
self.connect(self.phase_var_sub_avg, (self.phase_var_sqr,1))
self.connect(self.phase_var_sqr, self.phase_var_avg, self.probe_phase_var)
# measure processing rate
self.measure_rate = grdab.measure_processing_rate(gr.sizeof_gr_complex, 2048000)
self.connect(self.input, self.measure_rate)
# debugging
if debug:
self.connect(self.fft, blocks.file_sink(gr.sizeof_gr_complex*dp.fft_length, "debug/ofdm_after_fft.dat"))
self.connect((self.cfs,0), blocks.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_after_cfs.dat"))
self.connect(self.phase_diff, blocks.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_diff_phasor.dat"))
self.connect((self.remove_pilot,0), blocks.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_pilot_removed.dat"))
self.connect((self.remove_pilot,1), blocks.file_sink(gr.sizeof_char, "debug/ofdm_after_cfs_trigger.dat"))
self.connect(self.deinterleave, blocks.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_deinterleaved.dat"))
if self.rp.equalize_magnitude:
self.connect(self.equalizer, blocks.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_equalizer.dat"))
if self.rp.softbits:
self.connect(self.softbit_interleaver, blocks.file_sink(gr.sizeof_float*dp.num_carriers*2, "debug/softbits.dat"))
def clear_state(self):
self.sync.clear_state()
def update_correction(self):
while self.run_interpolater_update_thread:
rate = self.rate_prober.level()
if rate!=0:
self.resample.set_interp_ratio(rate/self.dp.sample_rate)
sleep(0.1)
def stop(self):
if self.run_interpolater_update_thread:
self.run_interpolater_update_thread = False
self.updater.join()
|
