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# Copyright 2005,2006 Free Software Foundation, Inc.
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# This file is part of GNU Radio
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# GNU Radio is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3, or (at your option)
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# GNU Radio is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with GNU Radio; see the file COPYING. If not, write to
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# the Free Software Foundation, Inc., 51 Franklin Street,
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# Boston, MA 02110-1301, USA.
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# See gnuradio-examples/python/gmsk2 for examples
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differential BPSK modulation and demodulation.
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from gnuradio import gr, gru, modulation_utils
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from math import pi, sqrt
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from pprint import pprint
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# default values (used in __init__ and add_options)
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_def_samples_per_symbol = 2
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_def_costas_alpha = None
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_def_omega_relative_limit = 0.005
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# /////////////////////////////////////////////////////////////////////////////
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# /////////////////////////////////////////////////////////////////////////////
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class dbpsk_mod(gr.hier_block):
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def __init__(self, fg,
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samples_per_symbol=_def_samples_per_symbol,
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excess_bw=_def_excess_bw,
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gray_code=_def_gray_code,
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Hierarchical block for RRC-filtered differential BPSK modulation.
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The input is a byte stream (unsigned char) and the
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output is the complex modulated signal at baseband.
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@param samples_per_symbol: samples per baud >= 2
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@type samples_per_symbol: integer
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@param excess_bw: Root-raised cosine filter excess bandwidth
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@type excess_bw: float
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@param gray_code: Tell modulator to Gray code the bits
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@param verbose: Print information about modulator?
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@param log: Log modulation data to files?
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self._samples_per_symbol = samples_per_symbol
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self._excess_bw = excess_bw
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self._gray_code = gray_code
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if not isinstance(self._samples_per_symbol, int) or self._samples_per_symbol < 2:
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raise TypeError, ("sbp must be an integer >= 2, is %d" % self._samples_per_symbol)
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ntaps = 11 * self._samples_per_symbol
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arity = pow(2,self.bits_per_symbol())
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# turn bytes into k-bit vectors
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gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST)
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self.symbol_mapper = gr.map_bb(psk.binary_to_gray[arity])
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self.symbol_mapper = gr.map_bb(psk.binary_to_ungray[arity])
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self.diffenc = gr.diff_encoder_bb(arity)
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self.chunks2symbols = gr.chunks_to_symbols_bc(psk.constellation[arity])
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# pulse shaping filter
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self.rrc_taps = gr.firdes.root_raised_cosine(
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self._samples_per_symbol, # gain (samples_per_symbol since we're
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# interpolating by samples_per_symbol)
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self._samples_per_symbol, # sampling rate
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self._excess_bw, # excess bandwidth (roll-off factor)
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self.rrc_filter = gr.interp_fir_filter_ccf(self._samples_per_symbol,
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fg.connect(self.bytes2chunks, self.symbol_mapper, self.diffenc,
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self.chunks2symbols, self.rrc_filter)
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self._print_verbage()
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self._setup_logging()
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# Initialize base class
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gr.hier_block.__init__(self, self._fg, self.bytes2chunks, self.rrc_filter)
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def samples_per_symbol(self):
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return self._samples_per_symbol
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def bits_per_symbol(self=None): # static method that's also callable on an instance
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bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
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def add_options(parser):
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Adds DBPSK modulation-specific options to the standard parser
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parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
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help="set RRC excess bandwith factor [default=%default]")
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parser.add_option("", "--no-gray-code", dest="gray_code",
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action="store_false", default=True,
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help="disable gray coding on modulated bits (PSK)")
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add_options=staticmethod(add_options)
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def extract_kwargs_from_options(options):
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Given command line options, create dictionary suitable for passing to __init__
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return modulation_utils.extract_kwargs_from_options(dbpsk_mod.__init__,
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('self', 'fg'), options)
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extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
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def _print_verbage(self):
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print "bits per symbol = %d" % self.bits_per_symbol()
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print "Gray code = %s" % self._gray_code
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print "RRC roll-off factor = %.2f" % self._excess_bw
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def _setup_logging(self):
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print "Modulation logging turned on."
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self._fg.connect(self.bytes2chunks,
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gr.file_sink(gr.sizeof_char, "bytes2chunks.dat"))
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self._fg.connect(self.symbol_mapper,
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gr.file_sink(gr.sizeof_char, "graycoder.dat"))
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self._fg.connect(self.diffenc,
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gr.file_sink(gr.sizeof_char, "diffenc.dat"))
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self._fg.connect(self.chunks2symbols,
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gr.file_sink(gr.sizeof_gr_complex, "chunks2symbols.dat"))
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self._fg.connect(self.rrc_filter,
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gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat"))
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# /////////////////////////////////////////////////////////////////////////////
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# Differentially coherent detection of differentially encoded BPSK
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# /////////////////////////////////////////////////////////////////////////////
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class dbpsk_demod(gr.hier_block):
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def __init__(self, fg,
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samples_per_symbol=_def_samples_per_symbol,
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excess_bw=_def_excess_bw,
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costas_alpha=_def_costas_alpha,
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gain_mu=_def_gain_mu,
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omega_relative_limit=_def_omega_relative_limit,
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gray_code=_def_gray_code,
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verbose=_def_verbose,
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Hierarchical block for RRC-filtered differential BPSK demodulation
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The input is the complex modulated signal at baseband.
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The output is a stream of bits packed 1 bit per byte (LSB)
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@param fg: flow graph
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@param samples_per_symbol: samples per symbol >= 2
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@type samples_per_symbol: float
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@param excess_bw: Root-raised cosine filter excess bandwidth
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@type excess_bw: float
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@param costas_alpha: loop filter gain
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@type costas_alphas: float
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@param gain_mu: for M&M block
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@param mu: for M&M block
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@param omega_relative_limit: for M&M block
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@type omega_relative_limit: float
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@param gray_code: Tell modulator to Gray code the bits
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@type gray_code: bool
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@param verbose: Print information about modulator?
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@param debug: Print modualtion data to files?
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self._samples_per_symbol = samples_per_symbol
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self._excess_bw = excess_bw
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self._costas_alpha = costas_alpha
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self._gain_mu = gain_mu
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self._omega_relative_limit = omega_relative_limit
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self._gray_code = gray_code
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if samples_per_symbol < 2:
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raise TypeError, "samples_per_symbol must be >= 2, is %r" % (samples_per_symbol,)
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arity = pow(2,self.bits_per_symbol())
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# Automatic gain control
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scale = (1.0/16384.0)
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self.pre_scaler = gr.multiply_const_cc(scale) # scale the signal from full-range to +-1
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#self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
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self.agc = gr.feedforward_agc_cc(16, 1.0)
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# Costas loop (carrier tracking)
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# The Costas loop is not needed for BPSK, though it can help. Turn the Costas loop on
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# by setting an alpha value not None.
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if self._costas_alpha is not None:
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beta = .25 * self._costas_alpha * self._costas_alpha
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self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.002, -0.002, costas_order)
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ntaps = 11 * self._samples_per_symbol
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self.rrc_taps = gr.firdes.root_raised_cosine(
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self._samples_per_symbol, # sampling rate
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self._excess_bw, # excess bandwidth (roll-off factor)
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self.rrc_filter=gr.fir_filter_ccf(1, self.rrc_taps)
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# symbol clock recovery
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omega = self._samples_per_symbol
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gain_omega = .25 * self._gain_mu * self._gain_mu
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self.clock_recovery=gr.clock_recovery_mm_cc(omega, gain_omega,
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self._mu, self._gain_mu,
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self._omega_relative_limit)
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# find closest constellation point
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rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
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#print "rotated_const =", rotated_const
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self.diffdec = gr.diff_phasor_cc()
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#self.diffdec = gr.diff_decoder_bb(arity)
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self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
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self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
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self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
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# unpack the k bit vector into a stream of bits
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self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
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self._print_verbage()
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self._setup_logging()
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# Connect and Initialize base class
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if self._costas_alpha is not None: # With Costas Loop
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self._fg.connect(self.pre_scaler, self.agc, self.costas_loop,
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self.rrc_filter, self.clock_recovery, self.diffdec,
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self.slicer, self.symbol_mapper, self.unpack)
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else: # Without Costas Loop
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self._fg.connect(self.pre_scaler, self.agc,
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self.rrc_filter, self.clock_recovery, self.diffdec,
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self.slicer, self.symbol_mapper, self.unpack)
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gr.hier_block.__init__(self, self._fg, self.pre_scaler, self.unpack)
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def samples_per_symbol(self):
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return self._samples_per_symbol
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def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
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bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
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def _print_verbage(self):
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print "bits per symbol = %d" % self.bits_per_symbol()
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print "Gray code = %s" % self._gray_code
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print "RRC roll-off factor = %.2f" % self._excess_bw
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if self._costas_alpha is not None:
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print "Costas Loop alpha = %.5f" % self._costas_alpha
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print "Costas Loop is turned off"
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print "M&M symbol sync gain = %.5f" % self._gain_mu
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print "M&M symbol sync mu = %.5f" % self._mu
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print "M&M omega relative limit = %.5f" % self._omega_relative_limit
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def _setup_logging(self):
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print "Modulation logging turned on."
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self._fg.connect(self.pre_scaler,
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gr.file_sink(gr.sizeof_gr_complex, "prescaler.dat"))
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self._fg.connect(self.agc,
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gr.file_sink(gr.sizeof_gr_complex, "agc.dat"))
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if self._costas_alpha is not None:
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self._fg.connect(self.costas_loop,
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gr.file_sink(gr.sizeof_gr_complex, "costas_loop.dat"))
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self._fg.connect((self.costas_loop,1),
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gr.file_sink(gr.sizeof_gr_complex, "costas_error.dat"))
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self._fg.connect(self.rrc_filter,
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gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat"))
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self._fg.connect(self.clock_recovery,
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gr.file_sink(gr.sizeof_gr_complex, "clock_recovery.dat"))
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self._fg.connect((self.clock_recovery,1),
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gr.file_sink(gr.sizeof_gr_complex, "clock_recovery_error.dat"))
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self._fg.connect(self.diffdec,
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gr.file_sink(gr.sizeof_gr_complex, "diffdec.dat"))
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self._fg.connect(self.slicer,
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gr.file_sink(gr.sizeof_char, "slicer.dat"))
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self._fg.connect(self.symbol_mapper,
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gr.file_sink(gr.sizeof_char, "symbol_mapper.dat"))
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self._fg.connect(self.unpack,
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gr.file_sink(gr.sizeof_char, "unpack.dat"))
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def add_options(parser):
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Adds DBPSK demodulation-specific options to the standard parser
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parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
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help="set RRC excess bandwith factor [default=%default] (PSK)")
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parser.add_option("", "--no-gray-code", dest="gray_code",
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action="store_false", default=_def_gray_code,
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help="disable gray coding on modulated bits (PSK)")
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parser.add_option("", "--costas-alpha", type="float", default=None,
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help="set Costas loop alpha value [default=%default] (PSK)")
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parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
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help="set M&M symbol sync loop gain mu value [default=%default] (GMSK/PSK)")
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parser.add_option("", "--mu", type="float", default=_def_mu,
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help="set M&M symbol sync loop mu value [default=%default] (GMSK/PSK)")
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parser.add_option("", "--omega-relative-limit", type="float", default=_def_omega_relative_limit,
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help="M&M clock recovery omega relative limit [default=%default] (GMSK/PSK)")
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add_options=staticmethod(add_options)
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def extract_kwargs_from_options(options):
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Given command line options, create dictionary suitable for passing to __init__
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return modulation_utils.extract_kwargs_from_options(
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dbpsk_demod.__init__, ('self', 'fg'), options)
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extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
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# Add these to the mod/demod registry
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modulation_utils.add_type_1_mod('dbpsk', dbpsk_mod)
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modulation_utils.add_type_1_demod('dbpsk', dbpsk_demod)
added
removed
gnuradio-core/src/python/gnuradio/blksimpl/dbpsk.py
