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   1 #
   2 # Copyright 2005,2006 Free Software Foundation, Inc.
   3 #
   4 # This file is part of GNU Radio
   5 #
   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 2, or (at your option)
   9 # any later version.
  10 #
  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.
  15 #
  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.
  20 #
  21
  22 # See gnuradio-examples/python/digital for examples
  23
  24 """
  25 differential BPSK modulation and demodulation.
  26 """
  27
  28 from gnuradio import gr, gru, modulation_utils
  29 from math import pi, sqrt
  30 import psk
  31 import cmath
  32 import Numeric
  33 from pprint import pprint
  34
  35 # default values (used in __init__ and add_options)
  36 _def_samples_per_symbol = 2
  37 _def_excess_bw = 0.35
  38 _def_gray_code = True
  39 _def_verbose = False
  40 _def_log = False
  41
  42 _def_costas_alpha = 0.15
  43 _def_gain_mu = 0.1
  44 _def_mu = 0.5
  45 _def_omega_relative_limit = 0.005
  46
  47
  48 # /////////////////////////////////////////////////////////////////////////////
  49 #                             DBPSK modulator
  50 # /////////////////////////////////////////////////////////////////////////////
  51
  52 class dbpsk_mod(gr.hier_block2):
  53     def __init__(self,
  54                  samples_per_symbol=_def_samples_per_symbol,
  55                  excess_bw=_def_excess_bw,
  56                  gray_code=_def_gray_code,
  57                  verbose=_def_verbose,
  58                  log=_def_log):
  59         """
  60         Hierarchical block for RRC-filtered differential BPSK modulation.
  61
  62         The input is a byte stream (unsigned char) and the
  63         output is the complex modulated signal at baseband.
  64
  65         @param samples_per_symbol: samples per baud >= 2
  66         @type samples_per_symbol: integer
  67         @param excess_bw: Root-raised cosine filter excess bandwidth
  68         @type excess_bw: float
  69         @param gray_code: Tell modulator to Gray code the bits
  70         @type gray_code: bool
  71         @param verbose: Print information about modulator?
  72         @type verbose: bool
  73         @param log: Log modulation data to files?
  74         @type log: bool
  75         """
  76
  77         gr.hier_block2.__init__(self, "dbpsk_mod",
  78                                 gr.io_signature(1,1,gr.sizeof_char), # Input signature
  79                                 gr.io_signature(1,1,gr.sizeof_gr_complex)) # Output signature
  80
  81         self._samples_per_symbol = samples_per_symbol
  82         self._excess_bw = excess_bw
  83         self._gray_code = gray_code
  84
  85         if not isinstance(self._samples_per_symbol, int) or self._samples_per_symbol < 2:
  86             raise TypeError, ("sbp must be an integer >= 2, is %d" % self._samples_per_symbol)
  87
  88         ntaps = 11 * self._samples_per_symbol
  89
  90         arity = pow(2,self.bits_per_symbol())
  91
  92         # turn bytes into k-bit vectors
  93         self.bytes2chunks = \
  94           gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST)
  95
  96         if self._gray_code:
  97             self.symbol_mapper = gr.map_bb(psk.binary_to_gray[arity])
  98         else:
  99             self.symbol_mapper = gr.map_bb(psk.binary_to_ungray[arity])
 100
 101         self.diffenc = gr.diff_encoder_bb(arity)
 102
 103         self.chunks2symbols = gr.chunks_to_symbols_bc(psk.constellation[arity])
 104
 105         # pulse shaping filter
 106         self.rrc_taps = gr.firdes.root_raised_cosine(
 107             self._samples_per_symbol,   # gain (samples_per_symbol since we're
 108                                         # interpolating by samples_per_symbol)
 109             self._samples_per_symbol,   # sampling rate
 110             1.0,                        # symbol rate
 111             self._excess_bw,            # excess bandwidth (roll-off factor)
 112             ntaps)
 113         self.rrc_filter = gr.interp_fir_filter_ccf(self._samples_per_symbol,
 114                                                    self.rrc_taps)
 115
 116         self.define_component("bytes2chunks", self.bytes2chunks)
 117         self.define_component("symbol_mapper", self.symbol_mapper)
 118         self.define_component("diffenc", self.diffenc)
 119         self.define_component("chunks2symbols", self.chunks2symbols)
 120         self.define_component("rrc_filter", self.rrc_filter)
 121
 122         # Connect components
 123         self.connect("self", 0, "bytes2chunks", 0)
 124         self.connect("bytes2chunks", 0, "symbol_mapper", 0)
 125         self.connect("symbol_mapper", 0, "diffenc", 0)
 126         self.connect("diffenc", 0, "chunks2symbols", 0)
 127         self.connect("chunks2symbols", 0, "rrc_filter", 0)
 128         self.connect("rrc_filter", 0, "self", 0)
 129
 130         if verbose:
 131             self._print_verbage()
 132
 133         if log:
 134             self._setup_logging()
 135
 136     def samples_per_symbol(self):
 137         return self._samples_per_symbol
 138
 139     def bits_per_symbol(self=None):   # static method that's also callable on an instance
 140         return 1
 141     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 142
 143     def add_options(parser):
 144         """
 145         Adds DBPSK modulation-specific options to the standard parser
 146         """
 147         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 148                           help="set RRC excess bandwith factor [default=%default]")
 149         parser.add_option("", "--no-gray-code", dest="gray_code",
 150                           action="store_false", default=True,
 151                           help="disable gray coding on modulated bits (PSK)")
 152     add_options=staticmethod(add_options)
 153
 154     def extract_kwargs_from_options(options):
 155         """
 156         Given command line options, create dictionary suitable for passing to __init__
 157         """
 158         return modulation_utils.extract_kwargs_from_options(dbpsk_mod.__init__,
 159                                                             ('self', 'fg'), options)
 160     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 161
 162
 163     def _print_verbage(self):
 164         print "\nModulator:"
 165         print "bits per symbol = %d" % self.bits_per_symbol()
 166         print "Gray code = %s" % self._gray_code
 167         print "RRC roll-off factor = %.2f" % self._excess_bw
 168
 169     def _setup_logging(self):
 170         print "Modulation logging turned on."
 171         self.define_component("bytes2chunks_dat",
 172                               gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat"))
 173         self.define_component("symbol_mapper_dat",
 174                               gr.file_sink(gr.sizeof_char, "tx_symbol_mapper.dat"))
 175         self.define_component("diffenc_dat",
 176                               gr.file_sink(gr.sizeof_char, "tx_diffenc.dat"))
 177         self.define_component("chunks2symbols_dat",
 178                               gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat"))
 179         self.define_component("rrc_filter_dat",
 180                               gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat"))
 181
 182         self.connect("bytes2chunks", 0, "bytes2chunks_dat", 0)
 183         self.connect("symbol_mapper", 0, "symbol_mapper_dat", 0)
 184         self.connect("diffenc", 0, "diffenc_dat", 0)
 185         self.connect("chunks2symbols", 0, "chunks2symbols_dat", 0)
 186         self.connect("rrc_filter", 0, "rrc_filter_dat", 0)
 187
 188
 189 # /////////////////////////////////////////////////////////////////////////////
 190 #                             DBPSK demodulator
 191 #
 192 #      Differentially coherent detection of differentially encoded BPSK
 193 # /////////////////////////////////////////////////////////////////////////////
 194
 195 class dbpsk_demod(gr.hier_block2):
 196
 197     def __init__(self,
 198                  samples_per_symbol=_def_samples_per_symbol,
 199                  excess_bw=_def_excess_bw,
 200                  costas_alpha=_def_costas_alpha,
 201                  gain_mu=_def_gain_mu,
 202                  mu=_def_mu,
 203                  omega_relative_limit=_def_omega_relative_limit,
 204                  gray_code=_def_gray_code,
 205                  verbose=_def_verbose,
 206                  log=_def_log):
 207         """
 208         Hierarchical block for RRC-filtered differential BPSK demodulation
 209
 210         The input is the complex modulated signal at baseband.
 211         The output is a stream of bits packed 1 bit per byte (LSB)
 212
 213         @param samples_per_symbol: samples per symbol >= 2
 214         @type samples_per_symbol: float
 215         @param excess_bw: Root-raised cosine filter excess bandwidth
 216         @type excess_bw: float
 217         @param costas_alpha: loop filter gain
 218         @type costas_alphas: float
 219         @param gain_mu: for M&M block
 220         @type gain_mu: float
 221         @param mu: for M&M block
 222         @type mu: float
 223         @param omega_relative_limit: for M&M block
 224         @type omega_relative_limit: float
 225         @param gray_code: Tell modulator to Gray code the bits
 226         @type gray_code: bool
 227         @param verbose: Print information about modulator?
 228         @type verbose: bool
 229         @param debug: Print modualtion data to files?
 230         @type debug: bool
 231         """
 232
 233         gr.hier_block2.__init__(self, "dbpsk_demod",
 234                                 gr.io_signature(1,1,gr.sizeof_gr_complex), # Input signature
 235                                 gr.io_signature(1,1,gr.sizeof_char))       # Output signature
 236
 237
 238         self._samples_per_symbol = samples_per_symbol
 239         self._excess_bw = excess_bw
 240         self._costas_alpha = costas_alpha
 241         self._mm_gain_mu = gain_mu
 242         self._mm_mu = mu
 243         self._mm_omega_relative_limit = omega_relative_limit
 244         self._gray_code = gray_code
 245
 246         if samples_per_symbol < 2:
 247             raise TypeError, "samples_per_symbol must be >= 2, is %r" % (samples_per_symbol,)
 248
 249         arity = pow(2,self.bits_per_symbol())
 250
 251         # Automatic gain control
 252         scale = (1.0/16384.0)
 253         self.pre_scaler = gr.multiply_const_cc(scale)   # scale the signal from full-range to +-1
 254         #self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
 255         self.agc = gr.feedforward_agc_cc(16, 1.0)
 256
 257
 258         # RRC data filter
 259         ntaps = 11 * samples_per_symbol
 260         self.rrc_taps = gr.firdes.root_raised_cosine(
 261             1.0,                      # gain
 262             self._samples_per_symbol, # sampling rate
 263             1.0,                      # symbol rate
 264             self._excess_bw,          # excess bandwidth (roll-off factor)
 265             ntaps)
 266         self.rrc_filter=gr.interp_fir_filter_ccf(1, self.rrc_taps)
 267
 268         # symbol clock recovery
 269         self._mm_omega = self._samples_per_symbol
 270         self._mm_gain_omega = .25 * self._mm_gain_mu * self._mm_gain_mu
 271         self._costas_beta  = 0.25 * self._costas_alpha * self._costas_alpha
 272         fmin = -0.02
 273         fmax = 0.02
 274
 275         self.receiver=gr.mpsk_receiver_cc(arity, 0,
 276                                           self._costas_alpha, self._costas_beta,
 277                                           fmin, fmax,
 278                                           self._mm_mu, self._mm_gain_mu,
 279                                           self._mm_omega, self._mm_gain_omega,
 280                                           self._mm_omega_relative_limit)
 281
 282         # Using differential decoding
 283         self.diffdec = gr.diff_phasor_cc()
 284
 285         # find closest constellation point
 286         rot = 1
 287         rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
 288         self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
 289
 290         if self._gray_code:
 291             self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
 292         else:
 293             self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
 294
 295         # unpack the k bit vector into a stream of bits
 296         self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
 297
 298         # Define components
 299         self.define_component("pre_scaler", self.pre_scaler)
 300         self.define_component("agc", self.agc)
 301         self.define_component("rrc_filter", self.rrc_filter)
 302         self.define_component("receiver", self.receiver)
 303         self.define_component("slicer", self.slicer)
 304         self.define_component("diffdec", self.diffdec)
 305         self.define_component("symbol_mapper", self.symbol_mapper)
 306         self.define_component("unpack", self.unpack)
 307
 308         # Connect and Initialize base class
 309         self.connect("self", 0, "pre_scaler", 0)
 310         self.connect("pre_scaler", 0, "agc", 0)
 311         self.connect("agc", 0, "rrc_filter", 0)
 312         self.connect("rrc_filter", 0, "receiver", 0)
 313         self.connect("receiver", 0, "diffdec", 0)
 314         self.connect("diffdec", 0, "slicer", 0)
 315         self.connect("slicer", 0, "symbol_mapper", 0)
 316         self.connect("symbol_mapper", 0, "unpack", 0)
 317         self.connect("unpack", 0, "self", 0)
 318
 319         if verbose:
 320             self._print_verbage()
 321
 322         if log:
 323             self._setup_logging()
 324
 325     def samples_per_symbol(self):
 326         return self._samples_per_symbol
 327
 328     def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
 329         return 1
 330     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 331
 332     def _print_verbage(self):
 333         print "\nDemodulator:"
 334         print "bits per symbol:     %d"   % self.bits_per_symbol()
 335         print "Gray code:           %s"   % self._gray_code
 336         print "RRC roll-off factor: %.2f" % self._excess_bw
 337         print "Costas Loop alpha:   %.2e" % self._costas_alpha
 338         print "Costas Loop beta:    %.2e" % self._costas_beta
 339         print "M&M mu:              %.2f" % self._mm_mu
 340         print "M&M mu gain:         %.2e" % self._mm_gain_mu
 341         print "M&M omega:           %.2f" % self._mm_omega
 342         print "M&M omega gain:      %.2e" % self._mm_gain_omega
 343         print "M&M omega limit:     %.2f" % self._mm_omega_relative_limit
 344
 345     def _setup_logging(self):
 346         print "Demodulation logging turned on."
 347         self.define_component("prescaler_dat",
 348                               gr.file_sink(gr.sizeof_gr_complex, "rx_prescaler.dat"))
 349         self.define_component("agc_dat",
 350                               gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
 351         self.define_component("rrc_filter_dat",
 352                               gr.file_sink(gr.sizeof_gr_complex, "rx_rrc_filter.dat"))
 353         self.define_component("receiver_dat",
 354                               gr.file_sink(gr.sizeof_gr_complex, "rx_receiver.dat"))
 355         self.define_component("diffdec_dat",
 356                               gr.file_sink(gr.sizeof_gr_complex, "rx_diffdec.dat"))
 357         self.define_component("slicer_dat",
 358                               gr.file_sink(gr.sizeof_char, "rx_slicer.dat"))
 359         self.define_component("symbol_mapper_dat",
 360                               gr.file_sink(gr.sizeof_char, "rx_symbol_mapper.dat"))
 361         self.define_component("unpack_dat",
 362                               gr.file_sink(gr.sizeof_char, "rx_unpack.dat"))
 363
 364         self.connect("pre_scaler", 0, "prescaler_dat", 0)
 365         self.connect("agc", 0, "agc_dat", 0)
 366         self.connect("rrc_filter", 0, "rrc_filter_dat", 0)
 367         self.connect("receiver", 0, "receiver_dat", 0)
 368         self.connect("diffdec", 0, "diffdec_dat", 0)
 369         self.connect("slicer", 0, "slicer_dat", 0)
 370         self.connect("symbol_mapper", 0, "symbol_mapper_dat", 0)
 371         self.connect("unpack", 0, "unpack_dat", 0)
 372
 373
 374     def add_options(parser):
 375         """
 376         Adds DBPSK demodulation-specific options to the standard parser
 377         """
 378         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 379                           help="set RRC excess bandwith factor [default=%default] (PSK)")
 380         parser.add_option("", "--no-gray-code", dest="gray_code",
 381                           action="store_false", default=_def_gray_code,
 382                           help="disable gray coding on modulated bits (PSK)")
 383         parser.add_option("", "--costas-alpha", type="float", default=None,
 384                           help="set Costas loop alpha value [default=%default] (PSK)")
 385         parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
 386                           help="set M&M symbol sync loop gain mu value [default=%default] (GMSK/PSK)")
 387         parser.add_option("", "--mu", type="float", default=_def_mu,
 388                           help="set M&M symbol sync loop mu value [default=%default] (GMSK/PSK)")
 389         parser.add_option("", "--omega-relative-limit", type="float", default=_def_omega_relative_limit,
 390                           help="M&M clock recovery omega relative limit [default=%default] (GMSK/PSK)")
 391     add_options=staticmethod(add_options)
 392
 393     def extract_kwargs_from_options(options):
 394         """
 395         Given command line options, create dictionary suitable for passing to __init__
 396         """
 397         return modulation_utils.extract_kwargs_from_options(
 398                  dbpsk_demod.__init__, ('self'), options)
 399     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 400 #
 401 # Add these to the mod/demod registry
 402 #
 403 modulation_utils.add_type_1_mod('dbpsk', dbpsk_mod)
 404 modulation_utils.add_type_1_demod('dbpsk', dbpsk_demod)