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   1 #
   2 # Copyright 2005,2006,2007 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 3, 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 8PSK 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 from pprint import pprint
  33
  34 # default values (used in __init__ and add_options)
  35 _def_samples_per_symbol = 3
  36 _def_excess_bw = 0.35
  37 _def_gray_code = True
  38 _def_verbose = False
  39 _def_log = False
  40
  41 _def_costas_alpha = 0.01
  42 _def_gain_mu = 0.05
  43 _def_mu = 0.5
  44 _def_omega_relative_limit = 0.005
  45
  46
  47 # /////////////////////////////////////////////////////////////////////////////
  48 #                           DQPSK modulator
  49 # /////////////////////////////////////////////////////////////////////////////
  50
  51 class d8psk_mod(gr.hier_block2):
  52
  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, "d8psk_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 = 1
 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         # Connect components
 118         self.connect(self, self.bytes2chunks, self.symbol_mapper, self.chunks2symbols,
 119                      self.rrc_filter, self)
 120
 121         if verbose:
 122             self._print_verbage()
 123
 124         if log:
 125             self._setup_logging()
 126
 127
 128     def samples_per_symbol(self):
 129         return self._samples_per_symbol
 130
 131     def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
 132         return 3
 133     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 134
 135     def _print_verbage(self):
 136         print "\nModulator:"
 137         print "bits per symbol = %d" % self.bits_per_symbol()
 138         print "Gray code = %s" % self._gray_code
 139         print "RS roll-off factor = %f" % self._excess_bw
 140
 141     def _setup_logging(self):
 142         print "Modulation logging turned on."
 143         self.connect(self.bytes2chunks, gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat"))
 144         self.connect(self.symbol_mapper, gr.file_sink(gr.sizeof_char, "tx_symbol_mapper.dat"))
 145         self.connect(self.chunks2symbols, gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat"))
 146         self.connect(self.rrc_filter, gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat"))
 147
 148     def add_options(parser):
 149         """
 150         Adds 8PSK modulation-specific options to the standard parser
 151         """
 152         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 153                           help="set RRC excess bandwith factor [default=%default] (PSK)")
 154         parser.add_option("", "--no-gray-code", dest="gray_code",
 155                           action="store_false", default=_def_gray_code,
 156                           help="disable gray coding on modulated bits (PSK)")
 157     add_options=staticmethod(add_options)
 158
 159
 160     def extract_kwargs_from_options(options):
 161         """
 162         Given command line options, create dictionary suitable for passing to __init__
 163         """
 164         return modulation_utils.extract_kwargs_from_options(d8psk_mod.__init__,
 165                                                             ('self', 'fg'), options)
 166     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 167
 168
 169 # /////////////////////////////////////////////////////////////////////////////
 170 #                           D8PSK demodulator
 171 #
 172 # Differentially coherent detection of differentially encoded 8psk
 173 # /////////////////////////////////////////////////////////////////////////////
 174
 175 WITH_SYNC = False
 176 class d8psk_demod(gr.hier_block2):
 177
 178     def __init__(self,
 179                  samples_per_symbol=_def_samples_per_symbol,
 180                  excess_bw=_def_excess_bw,
 181                  costas_alpha=_def_costas_alpha,
 182                  gain_mu=_def_gain_mu,
 183                  mu=_def_mu,
 184                  omega_relative_limit=_def_omega_relative_limit,
 185                  gray_code=_def_gray_code,
 186                  verbose=_def_verbose,
 187                  log=_def_log):
 188         """
 189         Hierarchical block for RRC-filtered DQPSK demodulation
 190
 191         The input is the complex modulated signal at baseband.
 192         The output is a stream of bits packed 1 bit per byte (LSB)
 193
 194         @param samples_per_symbol: samples per symbol >= 2
 195         @type samples_per_symbol: float
 196         @param excess_bw: Root-raised cosine filter excess bandwidth
 197         @type excess_bw: float
 198         @param costas_alpha: loop filter gain
 199         @type costas_alphas: float
 200         @param gain_mu: for M&M block
 201         @type gain_mu: float
 202         @param mu: for M&M block
 203         @type mu: float
 204         @param omega_relative_limit: for M&M block
 205         @type omega_relative_limit: float
 206         @param gray_code: Tell modulator to Gray code the bits
 207         @type gray_code: bool
 208         @param verbose: Print information about modulator?
 209         @type verbose: bool
 210         @param debug: Print modualtion data to files?
 211         @type debug: bool
 212         """
 213
 214         gr.hier_block2.__init__(self, "d8psk_demod",
 215                                 gr.io_signature(1,1,gr.sizeof_gr_complex), # Input signature
 216                                 gr.io_signature(1,1,gr.sizeof_char))       # Output signature
 217
 218         self._samples_per_symbol = samples_per_symbol
 219         self._excess_bw = excess_bw
 220         self._costas_alpha = costas_alpha
 221         self._mm_gain_mu = gain_mu
 222         self._mm_mu = mu
 223         self._mm_omega_relative_limit = omega_relative_limit
 224         self._gray_code = gray_code
 225
 226         if samples_per_symbol < 2:
 227             raise TypeError, "sbp must be >= 2, is %d" % samples_per_symbol
 228
 229         arity = pow(2,self.bits_per_symbol())
 230
 231         # Automatic gain control
 232         scale = (1.0/16384.0)
 233         self.pre_scaler = gr.multiply_const_cc(scale)   # scale the signal from full-range to +-1
 234         #self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
 235         self.agc = gr.feedforward_agc_cc(16, 1.0)
 236
 237         # RRC data filter
 238         ntaps = 11 * samples_per_symbol
 239         self.rrc_taps = gr.firdes.root_raised_cosine(
 240             1.0,                      # gain
 241             self._samples_per_symbol, # sampling rate
 242             1.0,                      # symbol rate
 243             self._excess_bw,          # excess bandwidth (roll-off factor)
 244             ntaps)
 245         self.rrc_filter=gr.interp_fir_filter_ccf(1, self.rrc_taps)
 246
 247         # symbol clock recovery
 248         self._mm_omega = self._samples_per_symbol
 249         self._mm_gain_omega = .25 * self._mm_gain_mu * self._mm_gain_mu
 250         self._costas_beta  = 0.25 * self._costas_alpha * self._costas_alpha
 251         fmin = -0.05
 252         fmax = 0.05
 253
 254         self.receiver=gr.mpsk_receiver_cc(arity, 0,
 255                                           self._costas_alpha, self._costas_beta,
 256                                           fmin, fmax,
 257                                           self._mm_mu, self._mm_gain_mu,
 258                                           self._mm_omega, self._mm_gain_omega,
 259                                           self._mm_omega_relative_limit)
 260
 261         #self.diffdec = gr.diff_decoder_bb(arity)
 262
 263         # find closest constellation point
 264         rot = 1
 265         rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
 266         self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
 267
 268         if self._gray_code:
 269             self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
 270         else:
 271             self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
 272
 273
 274         # unpack the k bit vector into a stream of bits
 275         self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
 276
 277
 278         # Connect and Initialize base class
 279         self.connect(self, self.pre_scaler, self.agc, self.rrc_filter, self.receiver,
 280                      self.slicer, self.symbol_mapper, self.unpack, self)
 281
 282         if verbose:
 283             self._print_verbage()
 284
 285         if log:
 286             self._setup_logging()
 287
 288
 289     def samples_per_symbol(self):
 290         return self._samples_per_symbol
 291
 292     def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
 293         return 3
 294     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 295
 296     def _print_verbage(self):
 297         print "\nDemodulator:"
 298         print "bits per symbol:     %d"   % self.bits_per_symbol()
 299         print "Gray code:           %s"   % self._gray_code
 300         print "RRC roll-off factor: %.2f" % self._excess_bw
 301         print "Costas Loop alpha:   %.2e" % self._costas_alpha
 302         print "Costas Loop beta:    %.2e" % self._costas_beta
 303         print "M&M mu:              %.2f" % self._mm_mu
 304         print "M&M mu gain:         %.2e" % self._mm_gain_mu
 305         print "M&M omega:           %.2f" % self._mm_omega
 306         print "M&M omega gain:      %.2e" % self._mm_gain_omega
 307         print "M&M omega limit:     %.2f" % self._mm_omega_relative_limit
 308
 309
 310     def _setup_logging(self):
 311         print "Demodulation logging turned on."
 312         self.connect(self.pre_scaler, gr.file_sink(gr.sizeof_gr_complex, "rx_prescaler.dat"))
 313         self.connect(self.agc, gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
 314         self.connect(self.rrc_filter, gr.file_sink(gr.sizeof_gr_complex, "rx_rrc_filter.dat"))
 315         self.connect(self.receiver, gr.file_sink(gr.sizeof_gr_complex, "rx_receiver.dat"))
 316         self.connect(self.slicer, gr.file_sink(gr.sizeof_char, "rx_slicer.dat"))
 317         self.connect(self.symbol_mapper, gr.file_sink(gr.sizeof_char, "rx_symbol_mapper.dat"))
 318         self.connect(self.unpack, gr.file_sink(gr.sizeof_char, "rx_unpack.dat"))
 319
 320     def add_options(parser):
 321         """
 322         Adds modulation-specific options to the standard parser
 323         """
 324         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 325                           help="set RRC excess bandwith factor [default=%default] (PSK)")
 326         parser.add_option("", "--no-gray-code", dest="gray_code",
 327                           action="store_false", default=_def_gray_code,
 328                           help="disable gray coding on modulated bits (PSK)")
 329         parser.add_option("", "--costas-alpha", type="float", default=None,
 330                           help="set Costas loop alpha value [default=%default] (PSK)")
 331         parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
 332                           help="set M&M symbol sync loop gain mu value [default=%default] (PSK)")
 333         parser.add_option("", "--mu", type="float", default=_def_mu,
 334                           help="set M&M symbol sync loop mu value [default=%default] (PSK)")
 335     add_options=staticmethod(add_options)
 336
 337     def extract_kwargs_from_options(options):
 338         """
 339         Given command line options, create dictionary suitable for passing to __init__
 340         """
 341         return modulation_utils.extract_kwargs_from_options(
 342             d8psk_demod.__init__, ('self', 'fg'), options)
 343     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 344
 345
 346 #
 347 # Add these to the mod/demod registry
 348 #
 349 # NOT READY TO BE USED YET -- ENABLE AT YOUR OWN RISK
 350 #modulation_utils.add_type_1_mod('d8psk', d8psk_mod)
 351 #modulation_utils.add_type_1_demod('d8psk', d8psk_demod)