#

# 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 BPSK modulation and demodulation.

"""

from gnuradio import gr, gru, modulation_utils

from math import pi, sqrt, ceil

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 = 4e-3

_def_costas_alpha = 0.1

_def_timing_alpha = 0.100

_def_timing_beta = 0.010

_def_timing_max_dev = 1.5

# /////////////////////////////////////////////////////////////////////////////

#                             DBPSK modulator

# /////////////////////////////////////////////////////////////////////////////

class dbpsk2_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 differential BPSK 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 baud >= 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 log: Log modulation data to files?

        @type log: bool

        """

        gr.hier_block2.__init__(self, "dbpsk_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(self._samples_per_symbol, int) or self._samples_per_symbol < 2:

            raise TypeError, ("sbp must be an integer >= 2, is %d" % self._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)

        self.chunks2symbols = gr.chunks_to_symbols_bc(psk.constellation[arity])

        # pulse shaping filter

        nfilts = 32

        ntaps = nfilts * 11 * 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)

        # Connect

        self.connect(self, self.bytes2chunks, self.symbol_mapper, self.diffenc,

                     self.chunks2symbols, self.rrc_filter, self)

        if verbose:

            self._print_verbage()

        if log:

            self._setup_logging()

    def samples_per_symbol(self):

        return self._samples_per_symbol

    def bits_per_symbol(self=None):   # static method that's also callable on an instance

        return 1

    bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM

    def add_options(parser):

        """

        Adds DBPSK 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]")

        parser.add_option("", "--no-gray-code", dest="gray_code",

                          action="store_false", default=True,

                          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(dbpsk2_mod.__init__,

                                                            ('self',), options)

    extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)

    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: %.2f" % 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"))

# /////////////////////////////////////////////////////////////////////////////

#                             DBPSK demodulator

#

#      Differentially coherent detection of differentially encoded BPSK

# /////////////////////////////////////////////////////////////////////////////

class dbpsk2_demod(gr.hier_block2):

    def __init__(self,

                 samples_per_symbol=_def_samples_per_symbol,

                 excess_bw=_def_excess_bw,

                 freq_alpha=_def_freq_alpha,

                 costas_alpha=_def_costas_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 differential BPSK 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 costas_alpha: loop filter gain for phase/fine frequency recovery

        @type costas_alpha: float

        @param timing_alpha: loop alpha gain for timing recovery

        @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._costas_alpha = costas_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, "samples_per_symbol must be >= 2, is %r" % (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, 1.0)

        # 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(self._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._costas_beta  = 0.25 * self._costas_alpha * self._costas_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._costas_alpha,

                                             self._costas_beta,

                                             fmax, fmin, arity)

        # Do differential decoding based on phase change of symbols

        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 1

    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 "Costas Loop alpha:   %.2f" % self._costas_alpha

        print "Costas Loop beta:    %.2f" % self._costas_beta

        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

    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.clock_recov,

                     gr.file_sink(gr.sizeof_gr_complex, "rx_clock_recov.dat"))

        self.connect(self.time_recov,

                     gr.file_sink(gr.sizeof_gr_complex, "rx_time_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_symbol_mapper.dat"))

        self.connect(self.unpack,

                     gr.file_sink(gr.sizeof_char, "rx_unpack.dat"))

    def add_options(parser):

        """

        Adds DBPSK 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("", "--costas-alpha", type="float", default=None,

                          help="set Costas loop alpha value [default=%default] (PSK)")

        parser.add_option("", "--gain-alpha", type="float", default=_def_timing_alpha,

                          help="set timing symbol sync loop gain alpha value [default=%default] (GMSK/PSK)")

        parser.add_option("", "--gain-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_utils.extract_kwargs_from_options(

                 dbpsk2_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('dbpsk2', dbpsk2_mod)

modulation_utils.add_type_1_demod('dbpsk2', dbpsk2_demod)