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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 = 0.175
  42 _def_gain_mu = 0.175
  43 _def_mu = 0.5
  44 _def_omega_relative_limit = 0.005
  45
  46
  47 # /////////////////////////////////////////////////////////////////////////////
  48 #                           D8PSK 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         if verbose:
 118             self._print_verbage()
 119
 120         if log:
 121             self._setup_logging()
 122
 123         # Connect & Initialize base class
 124         self.connect(self, self.bytes2chunks, self.symbol_mapper, self.diffenc,
 125                      self.chunks2symbols, self.rrc_filter, self)
 126
 127     def samples_per_symbol(self):
 128         return self._samples_per_symbol
 129
 130     def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
 131         return 3
 132     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 133
 134     def _print_verbage(self):
 135         print "bits per symbol = %d" % self.bits_per_symbol()
 136         print "Gray code = %s" % self._gray_code
 137         print "RS roll-off factor = %f" % self._excess_bw
 138
 139     def _setup_logging(self):
 140         print "Modulation logging turned on."
 141         self.connect(self.bytes2chunks,
 142                      gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat"))
 143         self.connect(self.symbol_mapper,
 144                      gr.file_sink(gr.sizeof_char, "tx_graycoder.dat"))
 145         self.connect(self.diffenc,
 146                      gr.file_sink(gr.sizeof_char, "tx_diffenc.dat"))
 147         self.connect(self.chunks2symbols,
 148                      gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat"))
 149         self.connect(self.rrc_filter,
 150                      gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat"))
 151
 152     def add_options(parser):
 153         """
 154         Adds 8PSK modulation-specific options to the standard parser
 155         """
 156         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 157                           help="set RRC excess bandwith factor [default=%default] (PSK)")
 158         parser.add_option("", "--no-gray-code", dest="gray_code",
 159                           action="store_false", default=_def_gray_code,
 160                           help="disable gray coding on modulated bits (PSK)")
 161     add_options=staticmethod(add_options)
 162
 163
 164     def extract_kwargs_from_options(options):
 165         """
 166         Given command line options, create dictionary suitable for passing to __init__
 167         """
 168         return modulation_utils.extract_kwargs_from_options(d8psk_mod.__init__,
 169                                                             ('self',), options)
 170     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 171
 172
 173 # /////////////////////////////////////////////////////////////////////////////
 174 #                           D8PSK demodulator
 175 #
 176 # Differentially coherent detection of differentially encoded 8psk
 177 # /////////////////////////////////////////////////////////////////////////////
 178
 179 class d8psk_demod(gr.hier_block2):
 180
 181     def __init__(self,
 182                  samples_per_symbol=_def_samples_per_symbol,
 183                  excess_bw=_def_excess_bw,
 184                  costas_alpha=_def_costas_alpha,
 185                  gain_mu=_def_gain_mu,
 186                  mu=_def_mu,
 187                  omega_relative_limit=_def_omega_relative_limit,
 188                  gray_code=_def_gray_code,
 189                  verbose=_def_verbose,
 190                  log=_def_log):
 191         """
 192         Hierarchical block for RRC-filtered DQPSK demodulation
 193
 194         The input is the complex modulated signal at baseband.
 195         The output is a stream of bits packed 1 bit per byte (LSB)
 196
 197         @param samples_per_symbol: samples per symbol >= 2
 198         @type samples_per_symbol: float
 199         @param excess_bw: Root-raised cosine filter excess bandwidth
 200         @type excess_bw: float
 201         @param costas_alpha: loop filter gain
 202         @type costas_alphas: float
 203         @param gain_mu: for M&M block
 204         @type gain_mu: float
 205         @param mu: for M&M block
 206         @type mu: float
 207         @param omega_relative_limit: for M&M block
 208         @type omega_relative_limit: float
 209         @param gray_code: Tell modulator to Gray code the bits
 210         @type gray_code: bool
 211         @param verbose: Print information about modulator?
 212         @type verbose: bool
 213         @param debug: Print modualtion data to files?
 214         @type debug: bool
 215         """
 216
 217         gr.hier_block2.__init__(self, "d8psk_demod",
 218                                 gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
 219                                 gr.io_signature(1, 1, gr.sizeof_char))       # Output signature
 220
 221         self._samples_per_symbol = samples_per_symbol
 222         self._excess_bw = excess_bw
 223         self._costas_alpha = costas_alpha
 224         self._mm_gain_mu = gain_mu
 225         self._mm_mu = mu
 226         self._mm_omega_relative_limit = omega_relative_limit
 227         self._gray_code = gray_code
 228
 229         if samples_per_symbol < 2:
 230             raise TypeError, "sbp must be >= 2, is %d" % samples_per_symbol
 231
 232         arity = pow(2,self.bits_per_symbol())
 233
 234         # Automatic gain control
 235         scale = (1.0/16384.0)
 236         self.pre_scaler = gr.multiply_const_cc(scale)   # scale the signal from full-range to +-1
 237         #self.agc = gr.agc_cc(1e-2, 1, 1, 100)
 238         self.agc = gr.agc2_cc(1e-1, 1e-2, 1, 1, 100)
 239         #self.agc = gr.feedforward_agc_cc(16, 1.0)
 240
 241         # RRC data filter
 242         ntaps = 11 * samples_per_symbol
 243         self.rrc_taps = gr.firdes.root_raised_cosine(
 244             1.0,                      # gain
 245             self._samples_per_symbol, # sampling rate
 246             1.0,                      # symbol rate
 247             self._excess_bw,          # excess bandwidth (roll-off factor)
 248             ntaps)
 249         self.rrc_filter=gr.interp_fir_filter_ccf(1, self.rrc_taps)
 250
 251         # symbol clock recovery
 252         self._mm_omega = self._samples_per_symbol
 253         self._mm_gain_omega = .25 * self._mm_gain_mu * self._mm_gain_mu
 254         self._costas_beta  = 0.25 * self._costas_alpha * self._costas_alpha
 255         fmin = -0.025
 256         fmax = 0.025
 257
 258         self.receiver=gr.mpsk_receiver_cc(arity, 0,
 259                                          self._costas_alpha, self._costas_beta,
 260                                          fmin, fmax,
 261                                          self._mm_mu, self._mm_gain_mu,
 262                                          self._mm_omega, self._mm_gain_omega,
 263                                          self._mm_omega_relative_limit)
 264
 265         # Perform Differential decoding on the constellation
 266         self.diffdec = gr.diff_phasor_cc()
 267
 268         # find closest constellation point
 269         rot = 1
 270         rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
 271         self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
 272
 273         if self._gray_code:
 274             self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
 275         else:
 276             self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
 277
 278
 279         # unpack the k bit vector into a stream of bits
 280         self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
 281
 282         if verbose:
 283             self._print_verbage()
 284
 285         if log:
 286             self._setup_logging()
 287
 288         # Connect
 289         self.connect(self, self.pre_scaler, self.agc, self.rrc_filter, self.receiver,
 290                      self.diffdec, self.slicer, self.symbol_mapper, self.unpack, self)
 291
 292     def samples_per_symbol(self):
 293         return self._samples_per_symbol
 294
 295     def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
 296         return 3
 297     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 298
 299     def _print_verbage(self):
 300         print "\nDemodulator:"
 301         print "bits per symbol:     %d"   % self.bits_per_symbol()
 302         print "Gray code:           %s"   % self._gray_code
 303         print "RRC roll-off factor: %.2f" % self._excess_bw
 304         print "Costas Loop alpha:   %.2e" % self._costas_alpha
 305         print "Costas Loop beta:    %.2e" % self._costas_beta
 306         print "M&M mu:              %.2f" % self._mm_mu
 307         print "M&M mu gain:         %.2e" % self._mm_gain_mu
 308         print "M&M omega:           %.2f" % self._mm_omega
 309         print "M&M omega gain:      %.2e" % self._mm_gain_omega
 310         print "M&M omega limit:     %.2f" % self._mm_omega_relative_limit
 311
 312
 313     def _setup_logging(self):
 314         print "Modulation logging turned on."
 315         self.connect(self.pre_scaler,
 316                      gr.file_sink(gr.sizeof_gr_complex, "rx_prescaler.dat"))
 317         self.connect(self.agc,
 318                      gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
 319         self.connect(self.rrc_filter,
 320                      gr.file_sink(gr.sizeof_gr_complex, "rx_rrc_filter.dat"))
 321         self.connect(self.receiver,
 322                      gr.file_sink(gr.sizeof_gr_complex, "rx_receiver.dat"))
 323         self.connect(self.diffdec,
 324                      gr.file_sink(gr.sizeof_gr_complex, "rx_diffdec.dat"))
 325         self.connect(self.slicer,
 326                      gr.file_sink(gr.sizeof_char, "rx_slicer.dat"))
 327         self.connect(self.symbol_mapper,
 328                      gr.file_sink(gr.sizeof_char, "rx_gray_decoder.dat"))
 329         self.connect(self.unpack,
 330                      gr.file_sink(gr.sizeof_char, "rx_unpack.dat"))
 331
 332     def add_options(parser):
 333         """
 334         Adds modulation-specific options to the standard parser
 335         """
 336         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 337                           help="set RRC excess bandwith factor [default=%default] (PSK)")
 338         parser.add_option("", "--no-gray-code", dest="gray_code",
 339                           action="store_false", default=_def_gray_code,
 340                           help="disable gray coding on modulated bits (PSK)")
 341         parser.add_option("", "--costas-alpha", type="float", default=_def_costas_alpha,
 342                           help="set Costas loop alpha value [default=%default] (PSK)")
 343         parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
 344                           help="set M&M symbol sync loop gain mu value [default=%default] (PSK)")
 345         parser.add_option("", "--mu", type="float", default=_def_mu,
 346                           help="set M&M symbol sync loop mu value [default=%default] (PSK)")
 347     add_options=staticmethod(add_options)
 348
 349     def extract_kwargs_from_options(options):
 350         """
 351         Given command line options, create dictionary suitable for passing to __init__
 352         """
 353         return modulation_utils.extract_kwargs_from_options(
 354             d8psk_demod.__init__, ('self',), options)
 355     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 356
 357
 358 #
 359 # Add these to the mod/demod registry
 360 #
 361 # NOT READY TO BE USED YET -- ENABLE AT YOUR OWN RISK
 362 modulation_utils.add_type_1_mod('d8psk', d8psk_mod)
 363 modulation_utils.add_type_1_demod('d8psk', d8psk_demod)