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Diffstat (limited to 'gr-digital/python/dqpsk.py')
| -rw-r--r-- | gr-digital/python/dqpsk.py | 374 |
1 files changed, 374 insertions, 0 deletions
diff --git a/gr-digital/python/dqpsk.py b/gr-digital/python/dqpsk.py new file mode 100644 index 000000000..29afd5530 --- /dev/null +++ b/gr-digital/python/dqpsk.py @@ -0,0 +1,374 @@ +# +# Copyright 2009,2010,2011 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, modulation_utils2 +from math import pi, sqrt +import digital_swig, 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_damping = 0.4 +_def_phase_natfreq = 0.25 +_def_timing_alpha = 0.100 +_def_timing_beta = 0.010 +_def_timing_max_dev = 1.5 + + +# ///////////////////////////////////////////////////////////////////////////// +# 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 samples_per_symbol < 2: + raise TypeError, ("sbp must be >= 2, is %f" % 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 "RRC 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(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, + freq_alpha=_def_freq_alpha, + phase_damping=_def_phase_damping, + phase_natfreq=_def_phase_natfreq, + 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_damping: loop filter damping factor for phase/fine frequency recovery + @type phase_damping: float + @param phase_natfreq: loop filter natural frequency for phase/fine frequency recovery + @type phase_natfreq: 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, "dqpsk_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_damping = phase_damping + self._phase_natfreq = phase_natfreq + 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_recov = digital_swig.costas_loop_cc(self._phase_damping, + self._phase_natfreq, + 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.phase_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( + dqpsk_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('dqpsk', dqpsk_mod) +modulation_utils2.add_type_1_demod('dqpsk', dqpsk_demod) |