--- /dev/null
+#
+# Copyright 2005,2006,2007 Free Software Foundation, Inc.
+#
+# This file is part of GNU Radio
+#
+# GNU Radio is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GNU Radio is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Radio; see the file COPYING. If not, write to
+# the Free Software Foundation, Inc., 51 Franklin Street,
+# Boston, MA 02110-1301, USA.
+#
+
+# See gnuradio-examples/python/digital for examples
+
+"""
+differential QPSK modulation and demodulation.
+"""
+
+from gnuradio import gr, gru, modulation_utils
+from math import pi, sqrt
+import psk
+import cmath
+from pprint import pprint
+
+# default values (used in __init__ and add_options)
+_def_samples_per_symbol = 2
+_def_excess_bw = 0.35
+_def_gray_code = True
+_def_verbose = False
+_def_log = False
+
+_def_costas_alpha = 0.15
+_def_gain_mu = None
+_def_mu = 0.5
+_def_omega_relative_limit = 0.005
+
+
+# /////////////////////////////////////////////////////////////////////////////
+# DQPSK modulator
+# /////////////////////////////////////////////////////////////////////////////
+
+class dqpsk_mod(gr.hier_block2):
+
+ def __init__(self,
+ samples_per_symbol=_def_samples_per_symbol,
+ excess_bw=_def_excess_bw,
+ gray_code=_def_gray_code,
+ verbose=_def_verbose,
+ log=_def_log):
+ """
+ Hierarchical block for RRC-filtered QPSK modulation.
+
+ The input is a byte stream (unsigned char) and the
+ output is the complex modulated signal at baseband.
+
+ @param samples_per_symbol: samples per symbol >= 2
+ @type samples_per_symbol: integer
+ @param excess_bw: Root-raised cosine filter excess bandwidth
+ @type excess_bw: float
+ @param gray_code: Tell modulator to Gray code the bits
+ @type gray_code: bool
+ @param verbose: Print information about modulator?
+ @type verbose: bool
+ @param debug: Print modualtion data to files?
+ @type debug: bool
+ """
+
+ gr.hier_block2.__init__(self, "dqpsk_mod",
+ gr.io_signature(1, 1, gr.sizeof_char), # Input signature
+ gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
+
+ self._samples_per_symbol = samples_per_symbol
+ self._excess_bw = excess_bw
+ self._gray_code = gray_code
+
+ if not isinstance(samples_per_symbol, int) or samples_per_symbol < 2:
+ raise TypeError, ("sbp must be an integer >= 2, is %d" % samples_per_symbol)
+
+ ntaps = 11 * samples_per_symbol
+
+ arity = pow(2,self.bits_per_symbol())
+
+ # turn bytes into k-bit vectors
+ self.bytes2chunks = \
+ gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST)
+
+ if self._gray_code:
+ self.symbol_mapper = gr.map_bb(psk.binary_to_gray[arity])
+ else:
+ self.symbol_mapper = gr.map_bb(psk.binary_to_ungray[arity])
+
+ self.diffenc = gr.diff_encoder_bb(arity)
+
+ rot = .707 + .707j
+ rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
+ self.chunks2symbols = gr.chunks_to_symbols_bc(rotated_const)
+
+ # pulse shaping filter
+ self.rrc_taps = gr.firdes.root_raised_cosine(
+ self._samples_per_symbol, # gain (sps since we're interpolating by sps)
+ self._samples_per_symbol, # sampling rate
+ 1.0, # symbol rate
+ self._excess_bw, # excess bandwidth (roll-off factor)
+ ntaps)
+
+ self.rrc_filter = gr.interp_fir_filter_ccf(self._samples_per_symbol, self.rrc_taps)
+
+ if verbose:
+ self._print_verbage()
+
+ if log:
+ self._setup_logging()
+
+ # Connect & Initialize base class
+ self.connect(self, self.bytes2chunks, self.symbol_mapper, self.diffenc,
+ self.chunks2symbols, self.rrc_filter, self)
+
+ def samples_per_symbol(self):
+ return self._samples_per_symbol
+
+ def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
+ return 2
+ bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
+
+ def _print_verbage(self):
+ print "\nModulator:"
+ print "bits per symbol: %d" % self.bits_per_symbol()
+ print "Gray code: %s" % self._gray_code
+ print "RRS roll-off factor: %f" % self._excess_bw
+
+ def _setup_logging(self):
+ print "Modulation logging turned on."
+ self.connect(self.bytes2chunks,
+ gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat"))
+ self.connect(self.symbol_mapper,
+ gr.file_sink(gr.sizeof_char, "tx_graycoder.dat"))
+ self.connect(self.diffenc,
+ gr.file_sink(gr.sizeof_char, "tx_diffenc.dat"))
+ self.connect(self.chunks2symbols,
+ gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat"))
+ self.connect(self.rrc_filter,
+ gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat"))
+
+ def add_options(parser):
+ """
+ Adds QPSK modulation-specific options to the standard parser
+ """
+ parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
+ help="set RRC excess bandwith factor [default=%default] (PSK)")
+ parser.add_option("", "--no-gray-code", dest="gray_code",
+ action="store_false", default=_def_gray_code,
+ help="disable gray coding on modulated bits (PSK)")
+ add_options=staticmethod(add_options)
+
+
+ def extract_kwargs_from_options(options):
+ """
+ Given command line options, create dictionary suitable for passing to __init__
+ """
+ return modulation_utils.extract_kwargs_from_options(dqpsk_mod.__init__,
+ ('self',), options)
+ extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
+
+
+# /////////////////////////////////////////////////////////////////////////////
+# DQPSK demodulator
+#
+# Differentially coherent detection of differentially encoded qpsk
+# /////////////////////////////////////////////////////////////////////////////
+
+class dqpsk_demod(gr.hier_block2):
+
+ def __init__(self,
+ samples_per_symbol=_def_samples_per_symbol,
+ excess_bw=_def_excess_bw,
+ costas_alpha=_def_costas_alpha,
+ gain_mu=_def_gain_mu,
+ mu=_def_mu,
+ omega_relative_limit=_def_omega_relative_limit,
+ gray_code=_def_gray_code,
+ verbose=_def_verbose,
+ log=_def_log):
+ """
+ Hierarchical block for RRC-filtered DQPSK demodulation
+
+ The input is the complex modulated signal at baseband.
+ The output is a stream of bits packed 1 bit per byte (LSB)
+
+ @param samples_per_symbol: samples per symbol >= 2
+ @type samples_per_symbol: float
+ @param excess_bw: Root-raised cosine filter excess bandwidth
+ @type excess_bw: float
+ @param costas_alpha: loop filter gain
+ @type costas_alphas: float
+ @param gain_mu: for M&M block
+ @type gain_mu: float
+ @param mu: for M&M block
+ @type mu: float
+ @param omega_relative_limit: for M&M block
+ @type omega_relative_limit: float
+ @param gray_code: Tell modulator to Gray code the bits
+ @type gray_code: bool
+ @param verbose: Print information about modulator?
+ @type verbose: bool
+ @param debug: Print modualtion data to files?
+ @type debug: bool
+ """
+
+ gr.hier_block2.__init__(self, "dqpsk_demod",
+ gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
+ gr.io_signature(1, 1, gr.sizeof_char)) # Output signature
+
+ self._samples_per_symbol = samples_per_symbol
+ self._excess_bw = excess_bw
+ self._costas_alpha = costas_alpha
+ self._mm_gain_mu = gain_mu
+ self._mm_mu = mu
+ self._mm_omega_relative_limit = omega_relative_limit
+ self._gray_code = gray_code
+
+ if samples_per_symbol < 2:
+ raise TypeError, "sbp must be >= 2, is %d" % samples_per_symbol
+
+ arity = pow(2,self.bits_per_symbol())
+
+ # Automatic gain control
+ scale = (1.0/16384.0)
+ self.pre_scaler = gr.multiply_const_cc(scale) # scale the signal from full-range to +-1
+ #self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
+ self.agc = gr.feedforward_agc_cc(16, 2.0)
+
+ # RRC data filter
+ ntaps = 11 * samples_per_symbol
+ self.rrc_taps = gr.firdes.root_raised_cosine(
+ 1.0, # gain
+ self._samples_per_symbol, # sampling rate
+ 1.0, # symbol rate
+ self._excess_bw, # excess bandwidth (roll-off factor)
+ ntaps)
+ self.rrc_filter=gr.interp_fir_filter_ccf(1, self.rrc_taps)
+
+ if not self._mm_gain_mu:
+ sbs_to_mm = {2: 0.050, 3: 0.075, 4: 0.11, 5: 0.125, 6: 0.15, 7: 0.15}
+ self._mm_gain_mu = sbs_to_mm[samples_per_symbol]
+
+ self._mm_omega = self._samples_per_symbol
+ self._mm_gain_omega = .25 * self._mm_gain_mu * self._mm_gain_mu
+ self._costas_beta = 0.25 * self._costas_alpha * self._costas_alpha
+ fmin = -0.025
+ fmax = 0.025
+
+ self.receiver=gr.mpsk_receiver_cc(arity, pi/4.0,
+ self._costas_alpha, self._costas_beta,
+ fmin, fmax,
+ self._mm_mu, self._mm_gain_mu,
+ self._mm_omega, self._mm_gain_omega,
+ self._mm_omega_relative_limit)
+
+ # Perform Differential decoding on the constellation
+ self.diffdec = gr.diff_phasor_cc()
+
+ # find closest constellation point
+ rot = 1
+ rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
+ self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
+
+ if self._gray_code:
+ self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
+ else:
+ self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
+
+ # unpack the k bit vector into a stream of bits
+ self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
+
+ if verbose:
+ self._print_verbage()
+
+ if log:
+ self._setup_logging()
+
+ # Connect & Initialize base class
+ self.connect(self, self.pre_scaler, self.agc, self.rrc_filter, self.receiver,
+ self.diffdec, self.slicer, self.symbol_mapper, self.unpack, self)
+
+ def samples_per_symbol(self):
+ return self._samples_per_symbol
+
+ def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
+ return 2
+ bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
+
+ def _print_verbage(self):
+ print "\nDemodulator:"
+ print "bits per symbol: %d" % self.bits_per_symbol()
+ print "Gray code: %s" % self._gray_code
+ print "RRC roll-off factor: %.2f" % self._excess_bw
+ print "Costas Loop alpha: %.2e" % self._costas_alpha
+ print "Costas Loop beta: %.2e" % self._costas_beta
+ print "M&M mu: %.2f" % self._mm_mu
+ print "M&M mu gain: %.2e" % self._mm_gain_mu
+ print "M&M omega: %.2f" % self._mm_omega
+ print "M&M omega gain: %.2e" % self._mm_gain_omega
+ print "M&M omega limit: %.2f" % self._mm_omega_relative_limit
+
+ def _setup_logging(self):
+ print "Modulation logging turned on."
+ self.connect(self.pre_scaler,
+ gr.file_sink(gr.sizeof_gr_complex, "rx_prescaler.dat"))
+ self.connect(self.agc,
+ gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
+ self.connect(self.rrc_filter,
+ gr.file_sink(gr.sizeof_gr_complex, "rx_rrc_filter.dat"))
+ self.connect(self.receiver,
+ gr.file_sink(gr.sizeof_gr_complex, "rx_receiver.dat"))
+ self.connect(self.diffdec,
+ gr.file_sink(gr.sizeof_gr_complex, "rx_diffdec.dat"))
+ self.connect(self.slicer,
+ gr.file_sink(gr.sizeof_char, "rx_slicer.dat"))
+ self.connect(self.symbol_mapper,
+ gr.file_sink(gr.sizeof_char, "rx_gray_decoder.dat"))
+ self.connect(self.unpack,
+ gr.file_sink(gr.sizeof_char, "rx_unpack.dat"))
+
+ def add_options(parser):
+ """
+ Adds modulation-specific options to the standard parser
+ """
+ parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
+ help="set RRC excess bandwith factor [default=%default] (PSK)")
+ parser.add_option("", "--no-gray-code", dest="gray_code",
+ action="store_false", default=_def_gray_code,
+ help="disable gray coding on modulated bits (PSK)")
+ parser.add_option("", "--costas-alpha", type="float", default=_def_costas_alpha,
+ help="set Costas loop alpha value [default=%default] (PSK)")
+ parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
+ help="set M&M symbol sync loop gain mu value [default=%default] (PSK)")
+ parser.add_option("", "--mu", type="float", default=_def_mu,
+ help="set M&M symbol sync loop mu value [default=%default] (PSK)")
+ add_options=staticmethod(add_options)
+
+ def extract_kwargs_from_options(options):
+ """
+ Given command line options, create dictionary suitable for passing to __init__
+ """
+ return modulation_utils.extract_kwargs_from_options(
+ dqpsk_demod.__init__, ('self',), options)
+ extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
+
+
+#
+# Add these to the mod/demod registry
+#
+modulation_utils.add_type_1_mod('dqpsk', dqpsk_mod)
+modulation_utils.add_type_1_demod('dqpsk', dqpsk_demod)
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