[Commit-gnuradio] r4059 - gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl

[trondeau]

Author: trondeau
Date: 2006-12-11 10:19:58 -0700 (Mon, 11 Dec 2006)
New Revision: 4059

Added:
   
gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl/qam.py
Log:
base to support QAM modulations; does automatic Gray coding for constellations

Added: 
gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl/qam.py
===================================================================
--- 
gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl/qam.py
                         (rev 0)
+++ 
gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl/qam.py
 2006-12-11 17:19:58 UTC (rev 4059)
@@ -0,0 +1,113 @@
+#
+# 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 2, 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
+import math
+
+# These constellations are generated for Gray coding when symbos [1, ..., m] 
are used
+# Mapping to Gray coding is therefore unnecessary
+
+def make_constellation(m):
+    # number of bits/symbol (log2(M))
+    k = int(math.log10(m) / math.log10(2.0))
+
+    coeff = 1
+    const_map = []
+    for i in range(m):
+        a = (i&(0x01 << k-1)) >> k-1
+        b = (i&(0x01 << k-2)) >> k-2
+        bits_i = [((i&(0x01 << k-j-1)) >> k-j-1) for j in range(2, k, 2)]
+        bits_q = [((i&(0x01 << k-j-1)) >> k-j-1) for j in range(3, k, 2)]
+
+        ss = 0
+        ll = len(bits_i)
+        for ii in range(ll):
+            rr = 0
+            for jj in range(ll-ii):
+                rr = abs(bits_i[jj] - rr)
+            ss += rr*pow(2.0, ii+1)
+        re = (2*a-1)*(ss+1)
+        
+        ss = 0
+        ll = len(bits_q)
+        for ii in range(ll):
+            rr = 0
+            for jj in range(ll-ii):
+                rr = abs(bits_q[jj] - rr)
+            ss += rr*pow(2.0, ii+1)
+        im = (2*b-1)*(ss+1)
+
+        a = max(re, im)
+        if a > coeff:
+            coeff = a
+        const_map.append(complex(re, im))
+
+    norm_map = [complex(i.real/coeff, i.imag/coeff) for i in const_map]
+    return norm_map
+        
+# Common definition of constellations for Tx and Rx
+constellation = {
+    4 :  make_constellation(4),           # QAM4 (QPSK)
+    8 :  make_constellation(8),           # QAM8
+    16:  make_constellation(16),          # QAM16
+    64:  make_constellation(64),          # QAM64
+    256: make_constellation(256)          # QAM256
+    }
+
+# -----------------------
+# Do Gray code
+# -----------------------
+# binary to gray coding
+binary_to_gray = {
+    4 : range(4),
+    8 : range(8),
+    16: range(16),
+    64: range(64),
+    256: range(256)
+    }
+   
+# gray to binary
+gray_to_binary = {
+    4 : range(4),
+    8 : range(8),
+    16: range(16),
+    64: range(64),
+    256: range(256)
+    }
+
+# -----------------------
+# Don't Gray code
+# -----------------------
+# identity mapping
+binary_to_ungray = {
+    4 : range(4),
+    8 : range(8),
+    16: range(16),
+    64: range(64)
+    }
+    
+# identity mapping
+ungray_to_binary = {
+    4 : range(4),
+    8 : range(8),
+    16: range(16),
+    64: range(64)
+    }