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#
# 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 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.
#
"""
PSK modulation and demodulation.
"""
from math import pi, log
from cmath import exp
from gnuradio import gr, modulation_utils2
from gnuradio.blks2impl.generic_mod_demod import generic_mod, generic_demod
# Default number of points in constellation.
_def_constellation_points = 4
# Whether differential coding is used.
_def_differential = True
# /////////////////////////////////////////////////////////////////////////////
# PSK constellation
# /////////////////////////////////////////////////////////////////////////////
def psk_constellation(m=_def_constellation_points):
"""
Creates a PSK constellation object.
"""
k = log(m) / log(2.0)
if (k != int(k)):
raise StandardError('Number of constellation points must be a power of two.')
points = [exp(2*pi*(0+1j)*i/m) for i in range(0,m)]
constellation = gr.constellation_psk(points, m)
return constellation
# /////////////////////////////////////////////////////////////////////////////
# PSK modulator
# /////////////////////////////////////////////////////////////////////////////
class psk_mod(generic_mod):
def __init__(self, constellation_points=_def_constellation_points,
*args, **kwargs):
"""
Hierarchical block for RRC-filtered PSK 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 = psk_constellation(constellation_points)
super(psk_mod, self).__init__(constellation, *args, **kwargs)
# /////////////////////////////////////////////////////////////////////////////
# PSK demodulator
#
# /////////////////////////////////////////////////////////////////////////////
class psk_demod(generic_demod):
def __init__(self, constellation_points=_def_constellation_points,
*args, **kwargs):
"""
Hierarchical block for RRC-filtered PSK modulation.
The input is a byte stream (unsigned char) and the
output is the complex modulated signal at baseband.
See generic_demod block for list of parameters.
"""
constellation = psk_constellation(constellation_points)
super(psk_demod, self).__init__(constellation, *args, **kwargs)
#
# Add these to the mod/demod registry
#
modulation_utils2.add_type_1_mod('psk', psk_mod)
modulation_utils2.add_type_1_demod('psk', psk_demod)
modulation_utils2.add_type_1_constellation('psk', psk_constellation)
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