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diff --git a/gr-digital/python/psk.py b/gr-digital/python/psk.py
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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.
+# 
+
+from math import pi, sqrt, log10
+import math, cmath
+
+# The following algorithm generates Gray coded constellations for M-PSK for M=[2,4,8]
+def make_gray_constellation(m):
+    # number of bits/symbol (log2(M))
+    k = int(log10(m) / log10(2.0))
+
+    coeff = 1
+    const_map = []
+    bits = [0]*3
+    for i in range(m):
+        # get a vector of the k bits to use in this mapping
+        bits[3-k:3] = [((i&(0x01 << k-j-1)) >> k-j-1) for j in range(k)]
+
+        theta = -(2*bits[0]-1)*(2*pi/m)*(bits[0]+abs(bits[1]-bits[2])+2*bits[1])
+        re = math.cos(theta)
+        im = math.sin(theta)
+        const_map.append(complex(re, im))   # plug it into the constellation
+    
+    # return the constellation; by default, it is normalized
+    return const_map
+
+# This makes a constellation that increments around the unit circle
+def make_constellation(m):
+    return [cmath.exp(i * 2 * pi / m * 1j) for i in range(m)]
+
+# Common definition of constellations for Tx and Rx
+constellation = {
+    2 : make_constellation(2),           # BPSK
+    4 : make_constellation(4),           # QPSK
+    8 : make_constellation(8)            # 8PSK
+    }
+
+gray_constellation = {
+    2 : make_gray_constellation(2),           # BPSK
+    4 : make_gray_constellation(4),           # QPSK
+    8 : make_gray_constellation(8)            # 8PSK
+    }
+
+# -----------------------
+# Do Gray code
+# -----------------------
+# binary to gray coding -- constellation does Gray coding
+binary_to_gray = {
+    2 : range(2),
+    4 : [0,1,3,2],
+    8 : [0, 1, 3, 2, 7, 6, 4, 5]
+    }
+
+# gray to binary
+gray_to_binary = {
+    2 : range(2),
+    4 : [0,1,3,2],
+    8 : [0, 1, 3, 2, 6, 7, 5, 4]
+    }
+
+# -----------------------
+# Don't Gray code
+# -----------------------
+# identity mapping
+binary_to_ungray = {
+    2 : range(2),
+    4 : range(4),
+    8 : range(8)
+    }
+
+# identity mapping
+ungray_to_binary = {
+    2 : range(2),
+    4 : range(4),
+    8 : range(8)
+    }