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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 QPSK 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 #                           DQPSK modulator
  50 # /////////////////////////////////////////////////////////////////////////////
  51
  52 class dqpsk_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 QPSK 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 symbol >= 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 debug: Print modualtion data to files?
  74         @type debug: bool
  75         """
  76
  77         gr.hier_block2.__init__(self, "dqpsk_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(samples_per_symbol, int) or samples_per_symbol < 2:
  86             raise TypeError, ("sbp must be an integer >= 2, is %d" % samples_per_symbol)
  87
  88         ntaps = 11 * 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         rot = .707 + .707j
 104         rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
 105         self.chunks2symbols = gr.chunks_to_symbols_bc(rotated_const)
 106
 107         # pulse shaping filter
 108         self.rrc_taps = gr.firdes.root_raised_cosine(
 109             self._samples_per_symbol, # gain  (sps since we're interpolating by sps)
 110             self._samples_per_symbol, # sampling rate
 111             1.0,                      # symbol rate
 112             self._excess_bw,          # excess bandwidth (roll-off factor)
 113             ntaps)
 114
 115         self.rrc_filter = gr.interp_fir_filter_ccf(self._samples_per_symbol, self.rrc_taps)
 116
 117         # Define components from objects
 118         self.define_component("bytes2chunks", self.bytes2chunks)
 119         self.define_component("symbol_mapper", self.symbol_mapper)
 120         self.define_component("diffenc", self.diffenc)
 121         self.define_component("chunks2symbols", self.chunks2symbols)
 122         self.define_component("rrc_filter", self.rrc_filter)
 123
 124         # Connect components
 125         self.connect("self", 0, "bytes2chunks", 0)
 126         self.connect("bytes2chunks", 0, "symbol_mapper", 0)
 127         self.connect("symbol_mapper", 0, "diffenc", 0)
 128         self.connect("diffenc", 0, "chunks2symbols", 0)
 129         self.connect("chunks2symbols", 0, "rrc_filter", 0)
 130         self.connect("rrc_filter", 0, "self", 0)
 131
 132         if verbose:
 133             self._print_verbage()
 134
 135         if log:
 136             self._setup_logging()
 137
 138     def samples_per_symbol(self):
 139         return self._samples_per_symbol
 140
 141     def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
 142         return 2
 143     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 144
 145     def _print_verbage(self):
 146         print "\nModulator:"
 147         print "bits per symbol = %d" % self.bits_per_symbol()
 148         print "Gray code = %s" % self._gray_code
 149         print "RRS roll-off factor = %f" % self._excess_bw
 150
 151     def _setup_logging(self):
 152         print "Modulation logging turned on."
 153         self.define_component("bytes2chunks_dat", gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat"))
 154         self.define_component("symbol_mapper_dat", gr.file_sink(gr.sizeof_char, "tx_symbol_mapper.dat"))
 155         self.define_component("diffenc_dat", gr.file_sink(gr.sizeof_char, "tx_diffenc.dat"))
 156         self.define_component("chunks2symbols_dat", gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat"))
 157         self.define_component("rrc_filter_dat", gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat"))
 158
 159         self.connect("bytes2chunks", 0, "bytes2chunks_dat", 0)
 160         self.connect("symbol_mapper", 0, "symbol_mapper_dat", 0)
 161         self.connect("diffenc", 0, "diffenc_dat", 0)
 162         self.connect("chunks2symbols", 0, "chunks2symbols_dat", 0)
 163         self.connect("rrc_filter", 0, "rrc_filter_dat", 0)
 164
 165     def add_options(parser):
 166         """
 167         Adds QPSK modulation-specific options to the standard parser
 168         """
 169         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 170                           help="set RRC excess bandwith factor [default=%default] (PSK)")
 171         parser.add_option("", "--no-gray-code", dest="gray_code",
 172                           action="store_false", default=_def_gray_code,
 173                           help="disable gray coding on modulated bits (PSK)")
 174     add_options=staticmethod(add_options)
 175
 176
 177     def extract_kwargs_from_options(options):
 178         """
 179         Given command line options, create dictionary suitable for passing to __init__
 180         """
 181         return modulation_utils.extract_kwargs_from_options(dqpsk_mod.__init__,
 182                                                             ('self', 'fg'), options)
 183     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 184
 185
 186 # /////////////////////////////////////////////////////////////////////////////
 187 #                           DQPSK demodulator
 188 #
 189 # Differentially coherent detection of differentially encoded qpsk
 190 # /////////////////////////////////////////////////////////////////////////////
 191
 192 class dqpsk_demod(gr.hier_block2):
 193
 194     def __init__(self,
 195                  samples_per_symbol=_def_samples_per_symbol,
 196                  excess_bw=_def_excess_bw,
 197                  costas_alpha=_def_costas_alpha,
 198                  gain_mu=_def_gain_mu,
 199                  mu=_def_mu,
 200                  omega_relative_limit=_def_omega_relative_limit,
 201                  gray_code=_def_gray_code,
 202                  verbose=_def_verbose,
 203                  log=_def_log):
 204         """
 205         Hierarchical block for RRC-filtered DQPSK demodulation
 206
 207         The input is the complex modulated signal at baseband.
 208         The output is a stream of bits packed 1 bit per byte (LSB)
 209
 210         @param samples_per_symbol: samples per symbol >= 2
 211         @type samples_per_symbol: float
 212         @param excess_bw: Root-raised cosine filter excess bandwidth
 213         @type excess_bw: float
 214         @param costas_alpha: loop filter gain
 215         @type costas_alphas: float
 216         @param gain_mu: for M&M block
 217         @type gain_mu: float
 218         @param mu: for M&M block
 219         @type mu: float
 220         @param omega_relative_limit: for M&M block
 221         @type omega_relative_limit: float
 222         @param gray_code: Tell modulator to Gray code the bits
 223         @type gray_code: bool
 224         @param verbose: Print information about modulator?
 225         @type verbose: bool
 226         @param debug: Print modualtion data to files?
 227         @type debug: bool
 228         """
 229
 230         gr.hier_block2.__init__(self, "dqpsk_demod",
 231                                 gr.io_signature(1,1,gr.sizeof_gr_complex), # Input signature
 232                                 gr.io_signature(1,1,gr.sizeof_char))       # Output signature
 233
 234         self._samples_per_symbol = samples_per_symbol
 235         self._excess_bw = excess_bw
 236         self._costas_alpha = costas_alpha
 237         self._mm_gain_mu = gain_mu
 238         self._mm_mu = mu
 239         self._mm_omega_relative_limit = omega_relative_limit
 240         self._gray_code = gray_code
 241
 242         if samples_per_symbol < 2:
 243             raise TypeError, "sbp must be >= 2, is %d" % samples_per_symbol
 244
 245         arity = pow(2,self.bits_per_symbol())
 246
 247         # Automatic gain control
 248         scale = (1.0/16384.0)
 249         self.pre_scaler = gr.multiply_const_cc(scale)   # scale the signal from full-range to +-1
 250         self.agc = gr.feedforward_agc_cc(16, 2.0)
 251
 252         # RRC data filter
 253         ntaps = 11 * samples_per_symbol
 254         self.rrc_taps = gr.firdes.root_raised_cosine(
 255             1.0,                      # gain
 256             self._samples_per_symbol, # sampling rate
 257             1.0,                      # symbol rate
 258             self._excess_bw,          # excess bandwidth (roll-off factor)
 259             ntaps)
 260         self.rrc_filter=gr.interp_fir_filter_ccf(1, self.rrc_taps)
 261
 262         # symbol clock recovery
 263         self._mm_omega = self._samples_per_symbol
 264         self._mm_gain_omega = .25 * self._mm_gain_mu * self._mm_gain_mu
 265         self._costas_beta  = 0.25 * self._costas_alpha * self._costas_alpha
 266         fmin = -0.01
 267         fmax = 0.01
 268
 269         self.receiver=gr.mpsk_receiver_cc(arity, pi/4.0,
 270                                          self._costas_alpha, self._costas_beta,
 271                                          fmin, fmax,
 272                                          self._mm_mu, self._mm_gain_mu,
 273                                          self._mm_omega, self._mm_gain_omega,
 274                                          self._mm_omega_relative_limit)
 275
 276         # Perform Differential decoding on the constellation
 277         self.diffdec = gr.diff_phasor_cc()
 278
 279         # find closest constellation point
 280         rot = 1
 281         rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
 282         self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
 283
 284         if self._gray_code:
 285             self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
 286         else:
 287             self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
 288
 289         # unpack the k bit vector into a stream of bits
 290         self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
 291
 292         # Define components
 293         self.define_component("pre_scaler", self.pre_scaler)
 294         self.define_component("agc", self.agc)
 295         self.define_component("rrc_filter", self.rrc_filter)
 296         self.define_component("receiver", self.receiver)
 297         self.define_component("diffdec", self.diffdec)
 298         self.define_component("slicer", self.slicer)
 299         self.define_component("symbol_mapper", self.symbol_mapper)
 300         self.define_component("unpack", self.unpack)
 301
 302         # Connect and Initialize base class
 303         self.connect("self", 0, "pre_scaler", 0)
 304         self.connect("pre_scaler", 0, "agc", 0)
 305         self.connect("agc", 0, "rrc_filter", 0)
 306         self.connect("rrc_filter", 0, "receiver", 0)
 307         self.connect("receiver", 0, "diffdec", 0)
 308         self.connect("diffdec", 0, "slicer", 0)
 309         self.connect("slicer", 0, "symbol_mapper", 0)
 310         self.connect("symbol_mapper", 0, "unpack", 0)
 311         self.connect("unpack", 0, "self", 0)
 312
 313         if verbose:
 314             self._print_verbage()
 315
 316         if log:
 317             self._setup_logging()
 318
 319     def samples_per_symbol(self):
 320         return self._samples_per_symbol
 321
 322     def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
 323         return 2
 324     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 325
 326     def _print_verbage(self):
 327         print "\nDemodulator:"
 328         print "bits per symbol:     %d"   % self.bits_per_symbol()
 329         print "Gray code:           %s"   % self._gray_code
 330         print "RRC roll-off factor: %.2f" % self._excess_bw
 331         print "Costas Loop alpha:   %.2e" % self._costas_alpha
 332         print "Costas Loop beta:    %.2e" % self._costas_beta
 333         print "M&M mu:              %.2f" % self._mm_mu
 334         print "M&M mu gain:         %.2e" % self._mm_gain_mu
 335         print "M&M omega:           %.2f" % self._mm_omega
 336         print "M&M omega gain:      %.2e" % self._mm_gain_omega
 337         print "M&M omega limit:     %.2f" % self._mm_omega_relative_limit
 338
 339     def _setup_logging(self):
 340         print "Demodulation logging turned on."
 341         self.define_component("prescaler_dat",
 342                               gr.file_sink(gr.sizeof_gr_complex, "rx_prescaler.dat"))
 343         self.define_component("agc_dat",
 344                               gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
 345         self.define_component("rrc_filter_dat",
 346                               gr.file_sink(gr.sizeof_gr_complex, "rx_rrc_filter.dat"))
 347         self.define_component("receiver_dat",
 348                               gr.file_sink(gr.sizeof_gr_complex, "rx_receiver.dat"))
 349         self.define_component("diffdec_dat",
 350                               gr.file_sink(gr.sizeof_gr_complex, "rx_diffdec.dat"))
 351         self.define_component("slicer_dat",
 352                               gr.file_sink(gr.sizeof_char, "rx_slicer.dat"))
 353         self.define_component("symbol_mapper_dat",
 354                               gr.file_sink(gr.sizeof_char, "rx_symbol_mapper.dat"))
 355         self.define_component("unpack_dat",
 356                               gr.file_sink(gr.sizeof_char, "rx_unpack.dat"))
 357
 358         self.connect("pre_scaler", 0, "prescaler_dat", 0)
 359         self.connect("agc", 0, "agc_dat", 0)
 360         self.connect("rrc_filter", 0, "rrc_filter_dat", 0)
 361         self.connect("receiver", 0, "receiver_dat", 0)
 362         self.connect("diffdec", 0, "diffdec_dat", 0)
 363         self.connect("slicer", 0, "slicer_dat", 0)
 364         self.connect("symbol_mapper", 0, "symbol_mapper_dat", 0)
 365         self.connect("unpack", 0, "unpack_dat", 0)
 366
 367     def add_options(parser):
 368         """
 369         Adds modulation-specific options to the standard parser
 370         """
 371         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 372                           help="set RRC excess bandwith factor [default=%default] (PSK)")
 373         parser.add_option("", "--no-gray-code", dest="gray_code",
 374                           action="store_false", default=_def_gray_code,
 375                           help="disable gray coding on modulated bits (PSK)")
 376         parser.add_option("", "--costas-alpha", type="float", default=None,
 377                           help="set Costas loop alpha value [default=%default] (PSK)")
 378         parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
 379                           help="set M&M symbol sync loop gain mu value [default=%default] (PSK)")
 380         parser.add_option("", "--mu", type="float", default=_def_mu,
 381                           help="set M&M symbol sync loop mu value [default=%default] (PSK)")
 382     add_options=staticmethod(add_options)
 383
 384     def extract_kwargs_from_options(options):
 385         """
 386         Given command line options, create dictionary suitable for passing to __init__
 387         """
 388         return modulation_utils.extract_kwargs_from_options(
 389             dqpsk_demod.__init__, ('self', 'fg'), options)
 390     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 391
 392
 393 #
 394 # Add these to the mod/demod registry
 395 #
 396 modulation_utils.add_type_1_mod('dqpsk', dqpsk_mod)
 397 modulation_utils.add_type_1_demod('dqpsk', dqpsk_demod)