#
# 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 QPSK modulation and demodulation.
"""
from gnuradio import gr, gru, modulation_utils
from math import pi, sqrt
import qam
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_costas_alpha = None
_def_gain_mu = 0.03
_def_mu = 0.05
_def_omega_relative_limit = 0.005
# /////////////////////////////////////////////////////////////////////////////
# QAM64 modulator
# /////////////////////////////////////////////////////////////////////////////
class qam64_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, "qam64_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(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(qam.binary_to_gray[arity])
else:
self.symbol_mapper = gr.map_bb(qam.binary_to_ungray[arity])
self.diffenc = gr.diff_encoder_bb(arity)
rot = 1.0
print "constellation with %d arity" % arity
rotated_const = map(lambda pt: pt * rot, qam.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
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 6
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.connect(self.bytes2chunks,
gr.file_sink(gr.sizeof_char, "bytes2chunks.dat"))
self.connect(self.symbol_mapper,
gr.file_sink(gr.sizeof_char, "graycoder.dat"))
self.connect(self.diffenc,
gr.file_sink(gr.sizeof_char, "diffenc.dat"))
self.connect(self.chunks2symbols,
gr.file_sink(gr.sizeof_gr_complex, "chunks2symbols.dat"))
self.connect(self.rrc_filter,
gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat"))
def add_options(parser):
"""
Adds QAM 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(qam64_mod.__init__,
('self',), options)
extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
# /////////////////////////////////////////////////////////////////////////////
# QAM16 demodulator
#
# /////////////////////////////////////////////////////////////////////////////
class qam64_demod(gr.hier_block2):
def __init__(self,
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):
gr.hier_block2.__init__(self, "qam64_demod",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
gr.io_signature(1, 1, gr.sizeof_char)) # Output signature
# do this
pass
def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
return 6
bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
#
# Add these to the mod/demod registry
#
# NOT READY TO BE USED YET -- ENABLE AT YOUR OWN RISK
#modulation_utils.add_type_1_mod('qam64', qam64_mod)
#modulation_utils.add_type_1_demod('qam16', qam16_demod)