2 # Copyright 2005,2006 Free Software Foundation, Inc.
4 # This file is part of GNU Radio
6 # GNU Radio is free software; you can redistribute it and/or modify
7 # it under the terms of the GNU General Public License as published by
8 # the Free Software Foundation; either version 3, or (at your option)
11 # GNU Radio is distributed in the hope that it will be useful,
12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 # GNU General Public License for more details.
16 # You should have received a copy of the GNU General Public License
17 # along with GNU Radio; see the file COPYING. If not, write to
18 # the Free Software Foundation, Inc., 51 Franklin Street,
19 # Boston, MA 02110-1301, USA.
22 # See gnuradio-examples/python/digital for examples
25 differential BPSK modulation and demodulation.
28 from gnuradio import gr, gru, modulation_utils
29 from math import pi, sqrt
32 from pprint import pprint
34 # default values (used in __init__ and add_options)
35 _def_samples_per_symbol = 2
41 _def_costas_alpha = 0.1
44 _def_omega_relative_limit = 0.005
47 # /////////////////////////////////////////////////////////////////////////////
49 # /////////////////////////////////////////////////////////////////////////////
51 class dbpsk_mod(gr.hier_block):
53 def __init__(self, fg,
54 samples_per_symbol=_def_samples_per_symbol,
55 excess_bw=_def_excess_bw,
56 gray_code=_def_gray_code,
60 Hierarchical block for RRC-filtered differential BPSK modulation.
62 The input is a byte stream (unsigned char) and the
63 output is the complex modulated signal at baseband.
67 @param samples_per_symbol: samples per baud >= 2
68 @type samples_per_symbol: integer
69 @param excess_bw: Root-raised cosine filter excess bandwidth
70 @type excess_bw: float
71 @param gray_code: Tell modulator to Gray code the bits
73 @param verbose: Print information about modulator?
75 @param log: Log modulation data to files?
80 self._samples_per_symbol = samples_per_symbol
81 self._excess_bw = excess_bw
82 self._gray_code = gray_code
84 if not isinstance(self._samples_per_symbol, int) or self._samples_per_symbol < 2:
85 raise TypeError, ("sbp must be an integer >= 2, is %d" % self._samples_per_symbol)
87 ntaps = 11 * self._samples_per_symbol
89 arity = pow(2,self.bits_per_symbol())
91 # turn bytes into k-bit vectors
93 gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST)
96 self.symbol_mapper = gr.map_bb(psk.binary_to_gray[arity])
98 self.symbol_mapper = gr.map_bb(psk.binary_to_ungray[arity])
100 self.diffenc = gr.diff_encoder_bb(arity)
102 self.chunks2symbols = gr.chunks_to_symbols_bc(psk.constellation[arity])
104 # pulse shaping filter
105 self.rrc_taps = gr.firdes.root_raised_cosine(
106 self._samples_per_symbol, # gain (samples_per_symbol since we're
107 # interpolating by samples_per_symbol)
108 self._samples_per_symbol, # sampling rate
110 self._excess_bw, # excess bandwidth (roll-off factor)
112 self.rrc_filter = gr.interp_fir_filter_ccf(self._samples_per_symbol,
116 fg.connect(self.bytes2chunks, self.symbol_mapper, self.diffenc,
117 self.chunks2symbols, self.rrc_filter)
120 self._print_verbage()
123 self._setup_logging()
125 # Initialize base class
126 gr.hier_block.__init__(self, self._fg, self.bytes2chunks, self.rrc_filter)
128 def samples_per_symbol(self):
129 return self._samples_per_symbol
131 def bits_per_symbol(self=None): # static method that's also callable on an instance
133 bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
135 def add_options(parser):
137 Adds DBPSK modulation-specific options to the standard parser
139 parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
140 help="set RRC excess bandwith factor [default=%default]")
141 parser.add_option("", "--no-gray-code", dest="gray_code",
142 action="store_false", default=True,
143 help="disable gray coding on modulated bits (PSK)")
144 add_options=staticmethod(add_options)
146 def extract_kwargs_from_options(options):
148 Given command line options, create dictionary suitable for passing to __init__
150 return modulation_utils.extract_kwargs_from_options(dbpsk_mod.__init__,
151 ('self', 'fg'), options)
152 extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
155 def _print_verbage(self):
157 print "bits per symbol: %d" % self.bits_per_symbol()
158 print "Gray code: %s" % self._gray_code
159 print "RRC roll-off factor: %.2f" % self._excess_bw
161 def _setup_logging(self):
162 print "Modulation logging turned on."
163 self._fg.connect(self.bytes2chunks,
164 gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat"))
165 self._fg.connect(self.symbol_mapper,
166 gr.file_sink(gr.sizeof_char, "tx_graycoder.dat"))
167 self._fg.connect(self.diffenc,
168 gr.file_sink(gr.sizeof_char, "tx_diffenc.dat"))
169 self._fg.connect(self.chunks2symbols,
170 gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat"))
171 self._fg.connect(self.rrc_filter,
172 gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat"))
175 # /////////////////////////////////////////////////////////////////////////////
178 # Differentially coherent detection of differentially encoded BPSK
179 # /////////////////////////////////////////////////////////////////////////////
181 class dbpsk_demod(gr.hier_block):
183 def __init__(self, fg,
184 samples_per_symbol=_def_samples_per_symbol,
185 excess_bw=_def_excess_bw,
186 costas_alpha=_def_costas_alpha,
187 gain_mu=_def_gain_mu,
189 omega_relative_limit=_def_omega_relative_limit,
190 gray_code=_def_gray_code,
191 verbose=_def_verbose,
194 Hierarchical block for RRC-filtered differential BPSK demodulation
196 The input is the complex modulated signal at baseband.
197 The output is a stream of bits packed 1 bit per byte (LSB)
199 @param fg: flow graph
201 @param samples_per_symbol: samples per symbol >= 2
202 @type samples_per_symbol: float
203 @param excess_bw: Root-raised cosine filter excess bandwidth
204 @type excess_bw: float
205 @param costas_alpha: loop filter gain
206 @type costas_alphas: float
207 @param gain_mu: for M&M block
209 @param mu: for M&M block
211 @param omega_relative_limit: for M&M block
212 @type omega_relative_limit: float
213 @param gray_code: Tell modulator to Gray code the bits
214 @type gray_code: bool
215 @param verbose: Print information about modulator?
217 @param debug: Print modualtion data to files?
222 self._samples_per_symbol = samples_per_symbol
223 self._excess_bw = excess_bw
224 self._costas_alpha = costas_alpha
225 self._mm_gain_mu = gain_mu
227 self._mm_omega_relative_limit = omega_relative_limit
228 self._gray_code = gray_code
230 if samples_per_symbol < 2:
231 raise TypeError, "samples_per_symbol must be >= 2, is %r" % (samples_per_symbol,)
233 arity = pow(2,self.bits_per_symbol())
235 # Automatic gain control
236 scale = (1.0/16384.0)
237 self.pre_scaler = gr.multiply_const_cc(scale) # scale the signal from full-range to +-1
238 #self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
239 self.agc = gr.feedforward_agc_cc(16, 2.0)
242 ntaps = 11 * samples_per_symbol
243 self.rrc_taps = gr.firdes.root_raised_cosine(
245 self._samples_per_symbol, # sampling rate
247 self._excess_bw, # excess bandwidth (roll-off factor)
249 self.rrc_filter=gr.interp_fir_filter_ccf(1, self.rrc_taps)
251 # symbol clock recovery
252 if not self._mm_gain_mu:
253 self._mm_gain_mu = 0.1
255 self._mm_omega = self._samples_per_symbol
256 self._mm_gain_omega = .25 * self._mm_gain_mu * self._mm_gain_mu
257 self._costas_beta = 0.25 * self._costas_alpha * self._costas_alpha
261 self.receiver=gr.mpsk_receiver_cc(arity, 0,
262 self._costas_alpha, self._costas_beta,
264 self._mm_mu, self._mm_gain_mu,
265 self._mm_omega, self._mm_gain_omega,
266 self._mm_omega_relative_limit)
268 # Do differential decoding based on phase change of symbols
269 self.diffdec = gr.diff_phasor_cc()
271 # find closest constellation point
273 rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
274 self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
277 self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
279 self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
281 # unpack the k bit vector into a stream of bits
282 self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
285 self._print_verbage()
288 self._setup_logging()
290 # Connect and Initialize base class
291 self._fg.connect(self.pre_scaler, self.agc, self.rrc_filter, self.receiver,
292 self.diffdec, self.slicer, self.symbol_mapper, self.unpack)
293 gr.hier_block.__init__(self, self._fg, self.pre_scaler, self.unpack)
295 def samples_per_symbol(self):
296 return self._samples_per_symbol
298 def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
300 bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
302 def _print_verbage(self):
303 print "\nDemodulator:"
304 print "bits per symbol: %d" % self.bits_per_symbol()
305 print "Gray code: %s" % self._gray_code
306 print "RRC roll-off factor: %.2f" % self._excess_bw
307 print "Costas Loop alpha: %.2e" % self._costas_alpha
308 print "Costas Loop beta: %.2e" % self._costas_beta
309 print "M&M mu: %.2f" % self._mm_mu
310 print "M&M mu gain: %.2e" % self._mm_gain_mu
311 print "M&M omega: %.2f" % self._mm_omega
312 print "M&M omega gain: %.2e" % self._mm_gain_omega
313 print "M&M omega limit: %.2f" % self._mm_omega_relative_limit
315 def _setup_logging(self):
316 print "Modulation logging turned on."
317 self._fg.connect(self.pre_scaler,
318 gr.file_sink(gr.sizeof_gr_complex, "rx_prescaler.dat"))
319 self._fg.connect(self.agc,
320 gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
321 self._fg.connect(self.rrc_filter,
322 gr.file_sink(gr.sizeof_gr_complex, "rx_rrc_filter.dat"))
323 self._fg.connect(self.receiver,
324 gr.file_sink(gr.sizeof_gr_complex, "rx_receiver.dat"))
325 self._fg.connect(self.diffdec,
326 gr.file_sink(gr.sizeof_gr_complex, "rx_diffdec.dat"))
327 self._fg.connect(self.slicer,
328 gr.file_sink(gr.sizeof_char, "rx_slicer.dat"))
329 self._fg.connect(self.symbol_mapper,
330 gr.file_sink(gr.sizeof_char, "rx_symbol_mapper.dat"))
331 self._fg.connect(self.unpack,
332 gr.file_sink(gr.sizeof_char, "rx_unpack.dat"))
334 def add_options(parser):
336 Adds DBPSK demodulation-specific options to the standard parser
338 parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
339 help="set RRC excess bandwith factor [default=%default] (PSK)")
340 parser.add_option("", "--no-gray-code", dest="gray_code",
341 action="store_false", default=_def_gray_code,
342 help="disable gray coding on modulated bits (PSK)")
343 parser.add_option("", "--costas-alpha", type="float", default=None,
344 help="set Costas loop alpha value [default=%default] (PSK)")
345 parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
346 help="set M&M symbol sync loop gain mu value [default=%default] (GMSK/PSK)")
347 parser.add_option("", "--mu", type="float", default=_def_mu,
348 help="set M&M symbol sync loop mu value [default=%default] (GMSK/PSK)")
349 parser.add_option("", "--omega-relative-limit", type="float", default=_def_omega_relative_limit,
350 help="M&M clock recovery omega relative limit [default=%default] (GMSK/PSK)")
351 add_options=staticmethod(add_options)
353 def extract_kwargs_from_options(options):
355 Given command line options, create dictionary suitable for passing to __init__
357 return modulation_utils.extract_kwargs_from_options(
358 dbpsk_demod.__init__, ('self', 'fg'), options)
359 extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
361 # Add these to the mod/demod registry
363 modulation_utils.add_type_1_mod('dbpsk', dbpsk_mod)
364 modulation_utils.add_type_1_demod('dbpsk', dbpsk_demod)