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diff --git a/gr-digital/python/psk2.py b/gr-digital/python/psk2.py
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+++ b/gr-digital/python/psk2.py
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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.
+# 
+
+"""
+PSK modulation and demodulation.
+"""
+
+from math import pi, log
+from cmath import exp
+
+from gnuradio import gr
+import digital_swig
+import modulation_utils2
+from utils import mod_codes, gray_code
+from generic_mod_demod import generic_mod, generic_demod
+
+# Default number of points in constellation.
+_def_constellation_points = 4
+# The default encoding (e.g. gray-code, set-partition)
+_def_mod_code = mod_codes.GRAY_CODE
+
+def create_encodings(mod_code, arity):
+    post_diff_code = None
+    if mod_code not in mod_codes.codes:
+        raise ValueError('That modulation code does not exist.')
+    if mod_code == mod_codes.GRAY_CODE:
+        pre_diff_code = gray_code.gray_code(arity)
+    elif mod_code == mod_codes.SET_PARTITION_CODE:
+        pre_diff_code = set_partition_code.set_partition_code(arity) 
+    elif mod_code == mod_codes.NO_CODE:
+        pre_diff_code = []
+    else:
+        raise ValueError('That modulation code is not implemented for this constellation.')
+    return (pre_diff_code, post_diff_code)
+    
+# /////////////////////////////////////////////////////////////////////////////
+#                           PSK constellation
+# /////////////////////////////////////////////////////////////////////////////
+
+def psk_constellation(m=_def_constellation_points, mod_code=_def_mod_code):
+    """
+    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)]
+    pre_diff_code, post_diff_code = create_encodings(mod_code, m)
+    if post_diff_code is not None:
+        inverse_post_diff_code = mod_codes.invert_code(post_diff_code)
+        points = [points[x] for x in inverse_post_diff_code]
+    constellation = digital_swig.constellation_psk(points, pre_diff_code, m)
+    return constellation
+
+# /////////////////////////////////////////////////////////////////////////////
+#                           PSK modulator
+# /////////////////////////////////////////////////////////////////////////////
+
+class psk_mod(generic_mod):
+
+    def __init__(self, constellation_points=_def_constellation_points,
+                 mod_code=_def_mod_code,
+                 *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, mod_code)
+        super(psk_mod, self).__init__(constellation, *args, **kwargs)
+
+# /////////////////////////////////////////////////////////////////////////////
+#                           PSK demodulator
+#
+# /////////////////////////////////////////////////////////////////////////////
+
+class psk_demod(generic_demod):
+
+    def __init__(self, constellation_points=_def_constellation_points,
+                 mod_code=_def_mod_code,
+                 *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, mod_code)
+        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)