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#
# 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 BPSK modulation and demodulation.
"""
from gnuradio import gr, modulation_utils2
from math import pi, sqrt, ceil
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
# /////////////////////////////////////////////////////////////////////////////
# DBPSK modulator
# /////////////////////////////////////////////////////////////////////////////
class dbpsk_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 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 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 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 * int(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_utils2.extract_kwargs_from_options(dbpsk_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 dbpsk_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 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 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: 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, "dbpsk_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 = 0.10*self._freq_alpha
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, "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.phase_recov = digital_swig.costas_loop_cc(self._phase_damping,
self._phase_natfreq,
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: %.2e" % self._freq_alpha
print "Timing alpha gain: %.2e" % self._timing_alpha
print "Timing beta gain: %.2e" % 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_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("", "--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(
dbpsk_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('dbpsk3', dbpsk_mod)
modulation_utils2.add_type_1_demod('dbpsk3', dbpsk_demod)
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