#
# Copyright 2005,2006 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 2, 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/gmsk2 for examples
"""
differential QPSK modulation and demodulation.
"""
from gnuradio import gr, gru, modulation_utils
from math import pi, sqrt
import psk
import cmath
import Numeric
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 = None
_def_gain_mu = 0.03
_def_mu = 0.05
_def_omega_relative_limit = 0.005
# /////////////////////////////////////////////////////////////////////////////
# DQPSK modulator
# /////////////////////////////////////////////////////////////////////////////
class dqpsk_mod(gr.hier_block):
def __init__(self, fg,
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 fg: flow graph
@type fg: flow graph
@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
"""
self._fg = fg
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._fg.connect(self.bytes2chunks, self.symbol_mapper, self.diffenc,
self.chunks2symbols, self.rrc_filter)
gr.hier_block.__init__(self, self._fg, self.bytes2chunks, self.rrc_filter)
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 "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._fg.connect(self.bytes2chunks,
gr.file_sink(gr.sizeof_char, "bytes2chunks.dat"))
self._fg.connect(self.symbol_mapper,
gr.file_sink(gr.sizeof_char, "graycoder.dat"))
self._fg.connect(self.diffenc,
gr.file_sink(gr.sizeof_char, "diffenc.dat"))
self._fg.connect(self.chunks2symbols,
gr.file_sink(gr.sizeof_gr_complex, "chunks2symbols.dat"))
self._fg.connect(self.rrc_filter,
gr.file_sink(gr.sizeof_gr_complex, "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', 'fg'), options)
extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
# /////////////////////////////////////////////////////////////////////////////
# DQPSK demodulator
#
# Differentially coherent detection of differentially encoded qpsk
# /////////////////////////////////////////////////////////////////////////////
class dqpsk_demod(gr.hier_block):
def __init__(self, fg,
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 fg: flow graph
@type fg: flow graph
@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
"""
self._fg = fg
self._samples_per_symbol = samples_per_symbol
self._excess_bw = excess_bw
self._costas_alpha = costas_alpha
self._gain_mu = gain_mu
self._mu = mu
self._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, 1.0)
# Costas loop (carrier tracking)
if self._costas_alpha is None: # If no alpha value was specified by the user
alpha_dir = {2:0.075, 3:0.09, 4:0.09, 5:0.095, 6:0.10, 7:0.105}
self._costas_alpha = alpha_dir[self._samples_per_symbol]
costas_order = 4
# The value of beta is now set to be underdamped; this value can have a huge impact on the
# performance of QPSK. Set to 0.25 for critically damped or higher for underdamped responses.
beta = .5 0 * self._costas_alpha * self._costas_alpha
self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.02, -0.02, costas_order)
# RRC data filter
ntaps = 11 * samples_per_symbol
self.rrc_taps = gr.firdes.root_raised_cosine(
self._samples_per_symbol, # gain
self._samples_per_symbol, # sampling rate
1.0, # symbol rate
self._excess_bw, # excess bandwidth (roll-off factor)
ntaps)
self.rrc_filter=gr.fir_filter_ccf(1, self.rrc_taps)
# symbol clock recovery
omega = self._samples_per_symbol
gain_omega = .25 * self._gain_mu * self._gain_mu
self.clock_recovery=gr.clock_recovery_mm_cc(omega, gain_omega,
self._mu, self._gain_mu,
self._omega_relative_limit)
self.diffdec = gr.diff_phasor_cc()
#self.diffdec = gr.diff_decoder_bb(arity)
# find closest constellation point
rot = 1
#rot = .707 + .707j
rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
#print "rotated_const = %s" % rotated_const
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._fg.connect(self.pre_scaler, self.agc, self.costas_loop,
self.rrc_filter, self.clock_recovery,
self.diffdec, self.slicer, self.symbol_mapper,
self.unpack)
gr.hier_block.__init__(self, self._fg, self.pre_scaler, self.unpack)
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 "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 = %.5f" % self._costas_alpha
print "M&M symbol sync gain = %.5f" % self._gain_mu
print "M&M symbol sync mu = %.5f" % self._mu
print "M&M omega relative limit = %.5f" % self._omega_relative_limit
def _setup_logging(self):
print "Modulation logging turned on."
self._fg.connect(self.pre_scaler,
gr.file_sink(gr.sizeof_gr_complex, "prescaler.dat"))
self._fg.connect(self.agc,
gr.file_sink(gr.sizeof_gr_complex, "agc.dat"))
self._fg.connect(self.costas_loop,
gr.file_sink(gr.sizeof_gr_complex, "costas_loop.dat"))
self._fg.connect((self.costas_loop,1),
gr.file_sink(gr.sizeof_gr_complex, "costas_error.dat"))
self._fg.connect(self.rrc_filter,
gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat"))
self._fg.connect(self.clock_recovery,
gr.file_sink(gr.sizeof_gr_complex, "clock_recovery.dat"))
self._fg.connect((self.clock_recovery,1),
gr.file_sink(gr.sizeof_gr_complex, "clock_recovery_error.dat"))
self._fg.connect(self.diffdec,
gr.file_sink(gr.sizeof_gr_complex, "diffdec.dat"))
self._fg.connect(self.slicer,
gr.file_sink(gr.sizeof_char, "slicer.dat"))
self._fg.connect(self.symbol_mapper,
gr.file_sink(gr.sizeof_char, "gray_decoder.dat"))
self._fg.connect(self.unpack,
gr.file_sink(gr.sizeof_char, "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=None,
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', 'fg'), 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)