From 28e086141aead2e43f958f0ae14d58cac557fa2d Mon Sep 17 00:00:00 2001
From: trondeau <trondeau@221aa14e-8319-0410-a670-987f0aec2ac5>
Date: Wed, 7 Mar 2007 04:31:19 +0000
Subject: merged trondeau/digital-wip2 r4193:4730 into trunk - improves digital
receiver and fixes ticket:72
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@4731 221aa14e-8319-0410-a670-987f0aec2ac5
---
gnuradio-core/src/python/gnuradio/blksimpl/psk.py | 57 ++++++++++++++++-------
1 file changed, 39 insertions(+), 18 deletions(-)
(limited to 'gnuradio-core/src/python/gnuradio/blksimpl/psk.py')
diff --git a/gnuradio-core/src/python/gnuradio/blksimpl/psk.py b/gnuradio-core/src/python/gnuradio/blksimpl/psk.py
index fdb6c9e693..58677b29d0 100644
--- a/gnuradio-core/src/python/gnuradio/blksimpl/psk.py
+++ b/gnuradio-core/src/python/gnuradio/blksimpl/psk.py
@@ -19,12 +19,33 @@
# Boston, MA 02110-1301, USA.
#
-from math import pi, sqrt
-import cmath
+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
@@ -35,18 +56,18 @@ constellation = {
# -----------------------
# Do Gray code
# -----------------------
-# binary to gray coding
+# binary to gray coding -- constellation does Gray coding
binary_to_gray = {
- 2 : (0, 1),
- 4 : (0, 1, 3, 2),
- 8 : (0, 1, 3, 2, 7, 6, 4, 5)
+ 2 : range(2),
+ 4 : [0,1,3,2],
+ 8 : [0, 1, 3, 2, 7, 6, 4, 5]
}
-
+
# gray to binary
gray_to_binary = {
- 2 : (0, 1),
- 4 : (0, 1, 3, 2),
- 8 : (0, 1, 3, 2, 6, 7, 5, 4)
+ 2 : range(2),
+ 4 : [0,1,3,2],
+ 8 : [0, 1, 3, 2, 6, 7, 5, 4]
}
# -----------------------
@@ -54,14 +75,14 @@ gray_to_binary = {
# -----------------------
# identity mapping
binary_to_ungray = {
- 2 : (0, 1),
- 4 : (0, 1, 2, 3),
- 8 : (0, 1, 2, 3, 4, 5, 6, 7)
+ 2 : range(2),
+ 4 : range(4),
+ 8 : range(8)
}
-
+
# identity mapping
ungray_to_binary = {
- 2 : (0, 1),
- 4 : (0, 1, 2, 3),
- 8 : (0, 1, 2, 3, 4, 5, 6, 7)
+ 2 : range(2),
+ 4 : range(4),
+ 8 : range(8)
}
--
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