From 41cf2b306a210c3600c1c35a8e952679a94c00a6 Mon Sep 17 00:00:00 2001
From: Tom Rondeau <trondeau@vt.edu>
Date: Mon, 29 Aug 2011 17:37:38 -0400
Subject: digital: created a separate DQPSK constellation that does not gray
code inside the block. This forces a slower decision making routine but
allows differential encoding. Gray coding is done using pre_diff_code.
---
gr-digital/lib/digital_constellation.cc | 80 +++++++++++++++++++++++++++++++++
1 file changed, 80 insertions(+)
(limited to 'gr-digital/lib/digital_constellation.cc')
diff --git a/gr-digital/lib/digital_constellation.cc b/gr-digital/lib/digital_constellation.cc
index 2263bba0bc..ed6d32bcb0 100644
--- a/gr-digital/lib/digital_constellation.cc
+++ b/gr-digital/lib/digital_constellation.cc
@@ -407,6 +407,20 @@ digital_constellation_qpsk::digital_constellation_qpsk ()
d_constellation[1] = gr_complex(SQRT_TWO, -SQRT_TWO);
d_constellation[2] = gr_complex(-SQRT_TWO, SQRT_TWO);
d_constellation[3] = gr_complex(SQRT_TWO, SQRT_TWO);
+
+ /*
+ d_constellation[0] = gr_complex(SQRT_TWO, SQRT_TWO);
+ d_constellation[1] = gr_complex(-SQRT_TWO, SQRT_TWO);
+ d_constellation[2] = gr_complex(SQRT_TWO, -SQRT_TWO);
+ d_constellation[3] = gr_complex(SQRT_TWO, -SQRT_TWO);
+ */
+
+ d_pre_diff_code.resize(4);
+ d_pre_diff_code[0] = 0x0;
+ d_pre_diff_code[1] = 0x2;
+ d_pre_diff_code[2] = 0x3;
+ d_pre_diff_code[3] = 0x1;
+
d_rotational_symmetry = 4;
d_dimensionality = 1;
calc_arity();
@@ -418,8 +432,74 @@ digital_constellation_qpsk::decision_maker(const gr_complex *sample)
// Real component determines small bit.
// Imag component determines big bit.
return 2*(imag(*sample)>0) + (real(*sample)>0);
+
+ /*
+ bool a = real(*sample) > 0;
+ bool b = imag(*sample) > 0;
+ if(a) {
+ if(b)
+ return 0x0;
+ else
+ return 0x1;
+ }
+ else {
+ if(b)
+ return 0x2;
+ else
+ return 0x3;
+ }
+ */
+}
+
+
+/********************************************************************/
+
+
+digital_constellation_dqpsk_sptr
+digital_make_constellation_dqpsk()
+{
+ return digital_constellation_dqpsk_sptr(new digital_constellation_dqpsk ());
}
+digital_constellation_dqpsk::digital_constellation_dqpsk ()
+{
+ d_constellation.resize(4);
+ d_constellation[0] = gr_complex(+SQRT_TWO, +SQRT_TWO);
+ d_constellation[1] = gr_complex(-SQRT_TWO, +SQRT_TWO);
+ d_constellation[2] = gr_complex(-SQRT_TWO, -SQRT_TWO);
+ d_constellation[3] = gr_complex(+SQRT_TWO, -SQRT_TWO);
+
+ d_pre_diff_code.resize(4);
+ d_pre_diff_code[0] = 0x0;
+ d_pre_diff_code[1] = 0x1;
+ d_pre_diff_code[2] = 0x3;
+ d_pre_diff_code[3] = 0x2;
+ d_apply_pre_diff_code = true;
+
+ d_rotational_symmetry = 4;
+ d_dimensionality = 1;
+ calc_arity();
+}
+
+#include <cstdio>
+unsigned int
+digital_constellation_dqpsk::decision_maker(const gr_complex *sample)
+{
+ bool a = real(*sample) > 0;
+ bool b = imag(*sample) > 0;
+ if(a) {
+ if(b)
+ return 0x0;
+ else
+ return 0x3;
+ }
+ else {
+ if(b)
+ return 0x1;
+ else
+ return 0x2;
+ }
+}
digital_constellation_8psk_sptr
digital_make_constellation_8psk()
--
cgit v1.2.3
From 5784b0c53c6d19b7a74f82e57c816beecd8b5edb Mon Sep 17 00:00:00 2001
From: Tom Rondeau <trondeau@vt.edu>
Date: Mon, 29 Aug 2011 17:58:25 -0400
Subject: digital: fixing qa code to test new dqpsk; a few minor formatting
changes.
---
gr-digital/lib/digital_constellation.cc | 8 +++++++-
gr-digital/lib/digital_constellation.h | 1 +
gr-digital/python/qa_constellation.py | 11 +++++------
3 files changed, 13 insertions(+), 7 deletions(-)
(limited to 'gr-digital/lib/digital_constellation.cc')
diff --git a/gr-digital/lib/digital_constellation.cc b/gr-digital/lib/digital_constellation.cc
index ed6d32bcb0..3dfc70273d 100644
--- a/gr-digital/lib/digital_constellation.cc
+++ b/gr-digital/lib/digital_constellation.cc
@@ -463,12 +463,16 @@ digital_make_constellation_dqpsk()
digital_constellation_dqpsk::digital_constellation_dqpsk ()
{
+ // This constellation is not gray coded, which allows
+ // us to use differential encodings (through gr_diff_encode and
+ // gr_diff_decode) on the symbols.
d_constellation.resize(4);
d_constellation[0] = gr_complex(+SQRT_TWO, +SQRT_TWO);
d_constellation[1] = gr_complex(-SQRT_TWO, +SQRT_TWO);
d_constellation[2] = gr_complex(-SQRT_TWO, -SQRT_TWO);
d_constellation[3] = gr_complex(+SQRT_TWO, -SQRT_TWO);
+ // Use this mapping to convert to gray code before diff enc.
d_pre_diff_code.resize(4);
d_pre_diff_code[0] = 0x0;
d_pre_diff_code[1] = 0x1;
@@ -481,10 +485,12 @@ digital_constellation_dqpsk::digital_constellation_dqpsk ()
calc_arity();
}
-#include <cstdio>
unsigned int
digital_constellation_dqpsk::decision_maker(const gr_complex *sample)
{
+ // Slower deicison maker as we can't slice along one axis.
+ // Maybe there's a better way to do this, still.
+
bool a = real(*sample) > 0;
bool b = imag(*sample) > 0;
if(a) {
diff --git a/gr-digital/lib/digital_constellation.h b/gr-digital/lib/digital_constellation.h
index fd773a9075..3e54e7d965 100644
--- a/gr-digital/lib/digital_constellation.h
+++ b/gr-digital/lib/digital_constellation.h
@@ -344,6 +344,7 @@ class digital_constellation_qpsk : public digital_constellation
/* */
/************************************************************/
+//! \brief DQPSK-specific constellation and decision maker
class digital_constellation_dqpsk;
typedef boost::shared_ptr<digital_constellation_dqpsk> digital_constellation_dqpsk_sptr;
diff --git a/gr-digital/python/qa_constellation.py b/gr-digital/python/qa_constellation.py
index 02afb8d2da..264ff7de64 100755
--- a/gr-digital/python/qa_constellation.py
+++ b/gr-digital/python/qa_constellation.py
@@ -70,10 +70,8 @@ tested_constellation_info = (
'mod_code': tested_mod_codes, },
True, None),
(digital_swig.constellation_bpsk, {}, True, None),
- # No differential testing for qpsk because it is gray-coded.
- # This is because soft decision making is simpler if we can assume
- # gray coding.
(digital_swig.constellation_qpsk, {}, False, None),
+ (digital_swig.constellation_dqpsk, {}, True, None),
(digital_swig.constellation_8psk, {}, False, None),
(twod_constell, {}, True, None),
(threed_constell, {}, True, None),
@@ -143,8 +141,8 @@ class test_constellation (gr_unittest.TestCase):
class mod_demod(gr.hier_block2):
def __init__(self, constellation, differential, rotation):
if constellation.arity() > 256:
- # If this becomes limiting some of the blocks should be generalised so that they can work
- # with shorts and ints as well as chars.
+ # If this becomes limiting some of the blocks should be generalised so
+ # that they can work with shorts and ints as well as chars.
raise ValueError("Constellation cannot contain more than 256 points.")
gr.hier_block2.__init__(self, "mod_demod",
@@ -174,7 +172,8 @@ class mod_demod(gr.hier_block2):
if self.differential:
self.blocks.append(gr.diff_encoder_bb(arity))
# Convert to constellation symbols.
- self.blocks.append(gr.chunks_to_symbols_bc(self.constellation.points(), self.constellation.dimensionality()))
+ self.blocks.append(gr.chunks_to_symbols_bc(self.constellation.points(),
+ self.constellation.dimensionality()))
# CHANNEL
# Channel just consists of a rotation to check differential coding.
if rotation is not None:
--
cgit v1.2.3