git.gag.com Git - debian/gnuradio/blob - gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py

   1 #
   2 # Copyright 2009,2010 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 QPSK modulation and demodulation.
  26 """
  27
  28 from gnuradio import gr, gru, modulation_utils2
  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 = 2
  36 _def_excess_bw = 0.35
  37 _def_gray_code = True
  38 _def_verbose = False
  39 _def_log = False
  40
  41 _def_freq_alpha = 0.010
  42 _def_phase_alpha = 0.01
  43 _def_timing_alpha = 0.100
  44 _def_timing_beta = 0.010
  45 _def_timing_max_dev = 1.5
  46
  47
  48 # /////////////////////////////////////////////////////////////////////////////
  49 #                           DQPSK modulator
  50 # /////////////////////////////////////////////////////////////////////////////
  51
  52 class dqpsk2_mod(gr.hier_block2):
  53
  54     def __init__(self,
  55                  samples_per_symbol=_def_samples_per_symbol,
  56                  excess_bw=_def_excess_bw,
  57                  gray_code=_def_gray_code,
  58                  verbose=_def_verbose,
  59                  log=_def_log):
  60         """
  61         Hierarchical block for RRC-filtered QPSK modulation.
  62
  63         The input is a byte stream (unsigned char) and the
  64         output is the complex modulated signal at baseband.
  65
  66         @param samples_per_symbol: samples per symbol >= 2
  67         @type samples_per_symbol: integer
  68         @param excess_bw: Root-raised cosine filter excess bandwidth
  69         @type excess_bw: float
  70         @param gray_code: Tell modulator to Gray code the bits
  71         @type gray_code: bool
  72         @param verbose: Print information about modulator?
  73         @type verbose: bool
  74         @param debug: Print modualtion data to files?
  75         @type debug: bool
  76         """
  77
  78         gr.hier_block2.__init__(self, "dqpsk2_mod",
  79                                 gr.io_signature(1, 1, gr.sizeof_char),       # Input signature
  80                                 gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
  81
  82         self._samples_per_symbol = samples_per_symbol
  83         self._excess_bw = excess_bw
  84         self._gray_code = gray_code
  85
  86         if samples_per_symbol < 2:
  87             raise TypeError, ("sbp must be >= 2, is %f" % samples_per_symbol)
  88
  89         ntaps = 11 * samples_per_symbol
  90
  91         arity = pow(2,self.bits_per_symbol())
  92
  93         # turn bytes into k-bit vectors
  94         self.bytes2chunks = \
  95           gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST)
  96
  97         if self._gray_code:
  98             self.symbol_mapper = gr.map_bb(psk.binary_to_gray[arity])
  99         else:
 100             self.symbol_mapper = gr.map_bb(psk.binary_to_ungray[arity])
 101
 102         self.diffenc = gr.diff_encoder_bb(arity)
 103
 104         rot = .707 + .707j
 105         rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
 106         self.chunks2symbols = gr.chunks_to_symbols_bc(rotated_const)
 107
 108         # pulse shaping filter
 109         nfilts = 32
 110         ntaps = 11 * int(nfilts * self._samples_per_symbol)  # make nfilts filters of ntaps each
 111         self.rrc_taps = gr.firdes.root_raised_cosine(
 112             nfilts,          # gain
 113             nfilts,          # sampling rate based on 32 filters in resampler
 114             1.0,             # symbol rate
 115             self._excess_bw, # excess bandwidth (roll-off factor)
 116             ntaps)
 117         self.rrc_filter = gr.pfb_arb_resampler_ccf(self._samples_per_symbol, self.rrc_taps)
 118
 119         if verbose:
 120             self._print_verbage()
 121
 122         if log:
 123             self._setup_logging()
 124
 125         # Connect & Initialize base class
 126         self.connect(self, self.bytes2chunks, self.symbol_mapper, self.diffenc,
 127                      self.chunks2symbols, self.rrc_filter, self)
 128
 129     def samples_per_symbol(self):
 130         return self._samples_per_symbol
 131
 132     def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
 133         return 2
 134     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 135
 136     def _print_verbage(self):
 137         print "\nModulator:"
 138         print "bits per symbol:     %d" % self.bits_per_symbol()
 139         print "Gray code:           %s" % self._gray_code
 140         print "RRS roll-off factor: %f" % self._excess_bw
 141
 142     def _setup_logging(self):
 143         print "Modulation logging turned on."
 144         self.connect(self.bytes2chunks,
 145                      gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat"))
 146         self.connect(self.symbol_mapper,
 147                      gr.file_sink(gr.sizeof_char, "tx_graycoder.dat"))
 148         self.connect(self.diffenc,
 149                      gr.file_sink(gr.sizeof_char, "tx_diffenc.dat"))
 150         self.connect(self.chunks2symbols,
 151                      gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat"))
 152         self.connect(self.rrc_filter,
 153                      gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat"))
 154
 155     def add_options(parser):
 156         """
 157         Adds QPSK modulation-specific options to the standard parser
 158         """
 159         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 160                           help="set RRC excess bandwith factor [default=%default] (PSK)")
 161         parser.add_option("", "--no-gray-code", dest="gray_code",
 162                           action="store_false", default=_def_gray_code,
 163                           help="disable gray coding on modulated bits (PSK)")
 164     add_options=staticmethod(add_options)
 165
 166
 167     def extract_kwargs_from_options(options):
 168         """
 169         Given command line options, create dictionary suitable for passing to __init__
 170         """
 171         return modulation_utils2.extract_kwargs_from_options(dqpsk2_mod.__init__,
 172                                                             ('self',), options)
 173     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 174
 175
 176 # /////////////////////////////////////////////////////////////////////////////
 177 #                           DQPSK demodulator
 178 #
 179 # Differentially coherent detection of differentially encoded qpsk
 180 # /////////////////////////////////////////////////////////////////////////////
 181
 182 class dqpsk2_demod(gr.hier_block2):
 183
 184     def __init__(self,
 185                  samples_per_symbol=_def_samples_per_symbol,
 186                  excess_bw=_def_excess_bw,
 187                  freq_alpha=_def_freq_alpha,
 188                  phase_alpha=_def_phase_alpha,
 189                  timing_alpha=_def_timing_alpha,
 190                  timing_max_dev=_def_timing_max_dev,
 191                  gray_code=_def_gray_code,
 192                  verbose=_def_verbose,
 193                  log=_def_log,
 194                  sync_out=False):
 195         """
 196         Hierarchical block for RRC-filtered DQPSK demodulation
 197
 198         The input is the complex modulated signal at baseband.
 199         The output is a stream of bits packed 1 bit per byte (LSB)
 200
 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 freq_alpha: loop filter gain for frequency recovery
 206         @type freq_alpha: float
 207         @param phase_alpha: loop filter gain
 208         @type phase_alphas: float
 209         @param timing_alpha: timing loop alpha gain
 210         @type timing_alpha: float
 211         @param timing_max: timing loop maximum rate deviations
 212         @type timing_max: float
 213         @param gray_code: Tell modulator to Gray code the bits
 214         @type gray_code: bool
 215         @param verbose: Print information about modulator?
 216         @type verbose: bool
 217         @param log: Print modualtion data to files?
 218         @type log: bool
 219         @param sync_out: Output a sync signal on :1?
 220         @type sync_out: bool
 221         """
 222         if sync_out: io_sig_out = gr.io_signaturev(2, 2, (gr.sizeof_char, gr.sizeof_gr_complex))
 223         else: io_sig_out = gr.io_signature(1, 1, gr.sizeof_char)
 224
 225         gr.hier_block2.__init__(self, "dqpsk2_demod",
 226                                 gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
 227                                 io_sig_out)       # Output signature
 228
 229         self._samples_per_symbol = samples_per_symbol
 230         self._excess_bw = excess_bw
 231         self._freq_alpha = freq_alpha
 232         self._freq_beta = 0.25*self._freq_alpha**2
 233         self._phase_alpha = phase_alpha
 234         self._timing_alpha = timing_alpha
 235         self._timing_beta = _def_timing_beta
 236         self._timing_max_dev=timing_max_dev
 237         self._gray_code = gray_code
 238
 239         if samples_per_symbol < 2:
 240             raise TypeError, "sbp must be >= 2, is %d" % samples_per_symbol
 241
 242         arity = pow(2,self.bits_per_symbol())
 243
 244         # Automatic gain control
 245         self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
 246         #self.agc = gr.feedforward_agc_cc(16, 2.0)
 247
 248         # Frequency correction
 249         self.freq_recov = gr.fll_band_edge_cc(self._samples_per_symbol, self._excess_bw,
 250                                               11*int(self._samples_per_symbol),
 251                                               self._freq_alpha, self._freq_beta)
 252
 253
 254         # symbol timing recovery with RRC data filter
 255         nfilts = 32
 256         ntaps = 11 * int(samples_per_symbol*nfilts)
 257         taps = gr.firdes.root_raised_cosine(nfilts, nfilts,
 258                                             1.0/float(self._samples_per_symbol),
 259                                             self._excess_bw, ntaps)
 260         self.time_recov = gr.pfb_clock_sync_ccf(self._samples_per_symbol,
 261                                                 self._timing_alpha,
 262                                                 taps, nfilts, nfilts/2, self._timing_max_dev)
 263         self.time_recov.set_beta(self._timing_beta)
 264
 265
 266         # Perform phase / fine frequency correction
 267         self._phase_beta  = 0.25 * self._phase_alpha * self._phase_alpha
 268         # Allow a frequency swing of +/- half of the sample rate
 269         fmin = -0.5
 270         fmax = 0.5
 271
 272         self.phase_recov = gr.costas_loop_cc(self._phase_alpha,
 273                                              self._phase_beta,
 274                                              fmax, fmin, arity)
 275
 276
 277         # Perform Differential decoding on the constellation
 278         self.diffdec = gr.diff_phasor_cc()
 279
 280         # find closest constellation point
 281         rot = 1
 282         rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
 283         self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
 284
 285         if self._gray_code:
 286             self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
 287         else:
 288             self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
 289
 290         # unpack the k bit vector into a stream of bits
 291         self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
 292
 293         if verbose:
 294             self._print_verbage()
 295
 296         if log:
 297             self._setup_logging()
 298
 299         # Connect
 300         self.connect(self, self.agc,
 301                      self.freq_recov, self.time_recov, self.phase_recov,
 302                      self.diffdec, self.slicer, self.symbol_mapper, self.unpack, self)
 303         if sync_out: self.connect(self.time_recov, (self, 1))
 304
 305     def samples_per_symbol(self):
 306         return self._samples_per_symbol
 307
 308     def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
 309         return 2
 310     bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
 311
 312     def _print_verbage(self):
 313         print "\nDemodulator:"
 314         print "bits per symbol:     %d"   % self.bits_per_symbol()
 315         print "Gray code:           %s"   % self._gray_code
 316         print "RRC roll-off factor: %.2f" % self._excess_bw
 317         print "FLL gain:            %.2f" % self._freq_alpha
 318         print "Timing alpha gain:   %.2f" % self._timing_alpha
 319         print "Timing beta gain:    %.2f" % self._timing_beta
 320         print "Timing max dev:      %.2f" % self._timing_max_dev
 321         print "Phase track alpha:   %.2e" % self._phase_alpha
 322         print "Phase track beta:    %.2e" % self._phase_beta
 323
 324     def _setup_logging(self):
 325         print "Modulation logging turned on."
 326         self.connect(self.agc,
 327                      gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
 328         self.connect(self.freq_recov,
 329                      gr.file_sink(gr.sizeof_gr_complex, "rx_freq_recov.dat"))
 330         self.connect(self.time_recov,
 331                      gr.file_sink(gr.sizeof_gr_complex, "rx_time_recov.dat"))
 332         self.connect(self.phase_recov,
 333                      gr.file_sink(gr.sizeof_gr_complex, "rx_phase_recov.dat"))
 334         self.connect(self.diffdec,
 335                      gr.file_sink(gr.sizeof_gr_complex, "rx_diffdec.dat"))
 336         self.connect(self.slicer,
 337                      gr.file_sink(gr.sizeof_char, "rx_slicer.dat"))
 338         self.connect(self.symbol_mapper,
 339                      gr.file_sink(gr.sizeof_char, "rx_gray_decoder.dat"))
 340         self.connect(self.unpack,
 341                      gr.file_sink(gr.sizeof_char, "rx_unpack.dat"))
 342
 343     def add_options(parser):
 344         """
 345         Adds DQPSK demodulation-specific options to the standard parser
 346         """
 347         parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
 348                           help="set RRC excess bandwith factor [default=%default] (PSK)")
 349         parser.add_option("", "--no-gray-code", dest="gray_code",
 350                           action="store_false", default=_def_gray_code,
 351                           help="disable gray coding on modulated bits (PSK)")
 352         parser.add_option("", "--freq-alpha", type="float", default=_def_freq_alpha,
 353                           help="set frequency lock loop alpha gain value [default=%default] (PSK)")
 354         parser.add_option("", "--phase-alpha", type="float", default=_def_phase_alpha,
 355                           help="set phase tracking loop alpha value [default=%default] (PSK)")
 356         parser.add_option("", "--timing-alpha", type="float", default=_def_timing_alpha,
 357                           help="set timing symbol sync loop gain alpha value [default=%default] (GMSK/PSK)")
 358         parser.add_option("", "--timing-beta", type="float", default=_def_timing_beta,
 359                           help="set timing symbol sync loop gain beta value [default=%default] (GMSK/PSK)")
 360         parser.add_option("", "--timing-max-dev", type="float", default=_def_timing_max_dev,
 361                           help="set timing symbol sync loop maximum deviation [default=%default] (GMSK/PSK)")
 362     add_options=staticmethod(add_options)
 363
 364     def extract_kwargs_from_options(options):
 365         """
 366         Given command line options, create dictionary suitable for passing to __init__
 367         """
 368         return modulation_utils2.extract_kwargs_from_options(
 369             dqpsk2_demod.__init__, ('self',), options)
 370     extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
 371
 372
 373 #
 374 # Add these to the mod/demod registry
 375 #
 376 modulation_utils2.add_type_1_mod('dqpsk2', dqpsk2_mod)
 377 modulation_utils2.add_type_1_demod('dqpsk2', dqpsk2_demod)