--- /dev/null
+#
+# Copyright 2009,2010 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_utils2
+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_freq_alpha = 0.010
+_def_phase_alpha = 0.01
+_def_timing_alpha = 0.100
+_def_timing_beta = 0.010
+_def_timing_max_dev = 1.5
+
+
+# /////////////////////////////////////////////////////////////////////////////
+# DQPSK modulator
+# /////////////////////////////////////////////////////////////////////////////
+
+class dqpsk2_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, "dqpsk2_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 samples_per_symbol < 2:
+ raise TypeError, ("sbp must be >= 2, is %f" % 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
+ nfilts = 32
+ ntaps = 11 * int(nfilts * self._samples_per_symbol) # make nfilts filters of ntaps each
+ self.rrc_taps = gr.firdes.root_raised_cosine(
+ nfilts, # gain
+ nfilts, # sampling rate based on 32 filters in resampler
+ 1.0, # symbol rate
+ self._excess_bw, # excess bandwidth (roll-off factor)
+ ntaps)
+ self.rrc_filter = gr.pfb_arb_resampler_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_utils2.extract_kwargs_from_options(dqpsk2_mod.__init__,
+ ('self',), options)
+ extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
+
+
+# /////////////////////////////////////////////////////////////////////////////
+# DQPSK demodulator
+#
+# Differentially coherent detection of differentially encoded qpsk
+# /////////////////////////////////////////////////////////////////////////////
+
+class dqpsk2_demod(gr.hier_block2):
+
+ def __init__(self,
+ samples_per_symbol=_def_samples_per_symbol,
+ excess_bw=_def_excess_bw,
+ freq_alpha=_def_freq_alpha,
+ phase_alpha=_def_phase_alpha,
+ timing_alpha=_def_timing_alpha,
+ timing_max_dev=_def_timing_max_dev,
+ gray_code=_def_gray_code,
+ verbose=_def_verbose,
+ log=_def_log,
+ sync_out=False):
+ """
+ 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 freq_alpha: loop filter gain for frequency recovery
+ @type freq_alpha: float
+ @param phase_alpha: loop filter gain
+ @type phase_alphas: float
+ @param timing_alpha: timing loop alpha gain
+ @type timing_alpha: float
+ @param timing_max: timing loop maximum rate deviations
+ @type timing_max: 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 log: Print modualtion data to files?
+ @type log: bool
+ @param sync_out: Output a sync signal on :1?
+ @type sync_out: bool
+ """
+ if sync_out: io_sig_out = gr.io_signaturev(2, 2, (gr.sizeof_char, gr.sizeof_gr_complex))
+ else: io_sig_out = gr.io_signature(1, 1, gr.sizeof_char)
+
+ gr.hier_block2.__init__(self, "dqpsk2_demod",
+ gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
+ io_sig_out) # Output signature
+
+ self._samples_per_symbol = samples_per_symbol
+ self._excess_bw = excess_bw
+ self._freq_alpha = freq_alpha
+ self._freq_beta = 0.25*self._freq_alpha**2
+ self._phase_alpha = phase_alpha
+ self._timing_alpha = timing_alpha
+ self._timing_beta = _def_timing_beta
+ self._timing_max_dev=timing_max_dev
+ 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
+ self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
+ #self.agc = gr.feedforward_agc_cc(16, 2.0)
+
+ # Frequency correction
+ self.freq_recov = gr.fll_band_edge_cc(self._samples_per_symbol, self._excess_bw,
+ 11*int(self._samples_per_symbol),
+ self._freq_alpha, self._freq_beta)
+
+
+ # symbol timing recovery with RRC data filter
+ nfilts = 32
+ ntaps = 11 * int(samples_per_symbol*nfilts)
+ taps = gr.firdes.root_raised_cosine(nfilts, nfilts,
+ 1.0/float(self._samples_per_symbol),
+ self._excess_bw, ntaps)
+ self.time_recov = gr.pfb_clock_sync_ccf(self._samples_per_symbol,
+ self._timing_alpha,
+ taps, nfilts, nfilts/2, self._timing_max_dev)
+ self.time_recov.set_beta(self._timing_beta)
+
+
+ # Perform phase / fine frequency correction
+ self._phase_beta = 0.25 * self._phase_alpha * self._phase_alpha
+ # Allow a frequency swing of +/- half of the sample rate
+ fmin = -0.5
+ fmax = 0.5
+
+ self.phase_recov = gr.costas_loop_cc(self._phase_alpha,
+ self._phase_beta,
+ fmax, fmin, arity)
+
+
+ # 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
+ self.connect(self, self.agc,
+ self.freq_recov, self.time_recov, self.phase_recov,
+ self.diffdec, self.slicer, self.symbol_mapper, self.unpack, self)
+ if sync_out: self.connect(self.time_recov, (self, 1))
+
+ 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 "FLL gain: %.2f" % self._freq_alpha
+ print "Timing alpha gain: %.2f" % self._timing_alpha
+ print "Timing beta gain: %.2f" % self._timing_beta
+ print "Timing max dev: %.2f" % self._timing_max_dev
+ print "Phase track alpha: %.2e" % self._phase_alpha
+ print "Phase track beta: %.2e" % self._phase_beta
+
+ def _setup_logging(self):
+ print "Modulation logging turned on."
+ self.connect(self.agc,
+ gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
+ self.connect(self.freq_recov,
+ gr.file_sink(gr.sizeof_gr_complex, "rx_freq_recov.dat"))
+ self.connect(self.time_recov,
+ gr.file_sink(gr.sizeof_gr_complex, "rx_time_recov.dat"))
+ self.connect(self.phase_recov,
+ gr.file_sink(gr.sizeof_gr_complex, "rx_phase_recov.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 DQPSK demodulation-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("", "--freq-alpha", type="float", default=_def_freq_alpha,
+ help="set frequency lock loop alpha gain value [default=%default] (PSK)")
+ parser.add_option("", "--phase-alpha", type="float", default=_def_phase_alpha,
+ help="set phase tracking loop alpha value [default=%default] (PSK)")
+ parser.add_option("", "--timing-alpha", type="float", default=_def_timing_alpha,
+ help="set timing symbol sync loop gain alpha value [default=%default] (GMSK/PSK)")
+ parser.add_option("", "--timing-beta", type="float", default=_def_timing_beta,
+ help="set timing symbol sync loop gain beta value [default=%default] (GMSK/PSK)")
+ parser.add_option("", "--timing-max-dev", type="float", default=_def_timing_max_dev,
+ help="set timing symbol sync loop maximum deviation [default=%default] (GMSK/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_utils2.extract_kwargs_from_options(
+ dqpsk2_demod.__init__, ('self',), options)
+ extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
+
+
+#
+# Add these to the mod/demod registry
+#
+modulation_utils2.add_type_1_mod('dqpsk2', dqpsk2_mod)
+modulation_utils2.add_type_1_demod('dqpsk2', dqpsk2_demod)
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