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#
# Copyright 2005,2006,2011 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.
#
"""
QPSK modulation.
Demodulation is not included since the generic_mod_demod
doesn't work for non-differential encodings.
"""
from gnuradio import gr, modulation_utils2
from gnuradio.digital.generic_mod_demod import generic_mod
# Default number of points in constellation.
_def_constellation_points = 4
# Whether differential coding is used.
_def_differential = False
_def_gray_coded = True
# /////////////////////////////////////////////////////////////////////////////
# QPSK constellation
# /////////////////////////////////////////////////////////////////////////////
def qpsk_constellation(m=_def_constellation_points):
if m != _def_constellation_points:
raise ValueError("QPSK can only have 4 constellation points.")
return gr.constellation_qpsk()
# /////////////////////////////////////////////////////////////////////////////
# QPSK modulator
# /////////////////////////////////////////////////////////////////////////////
class qpsk_mod(generic_mod):
def __init__(self, constellation_points=_def_constellation_points,
differential=_def_differential,
gray_coded=_def_gray_coded,
*args, **kwargs):
"""
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.
See generic_mod block for list of parameters.
"""
constellation = gr.constellation_qpsk()
if constellation_points != 4:
raise ValueError("QPSK can only have 4 constellation points.")
if differential or not gray_coded:
raise ValueError("This QPSK mod/demod works only for gray-coded, non-differential.")
super(qpsk_mod, self).__init__(constellation, differential, gray_coded, *args, **kwargs)
#
# Add these to the mod/demod registry
#
modulation_utils2.add_type_1_mod('qpsk', qpsk_mod)
modulation_utils2.add_type_1_constellation('qpsk', qpsk_constellation)
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