From d09833bc3db07e18e245426f5d8fd20bfa3d0b67 Mon Sep 17 00:00:00 2001
From: trondeau <trondeau@221aa14e-8319-0410-a670-987f0aec2ac5>
Date: Sun, 5 Nov 2006 21:14:00 +0000
Subject: merging from trondeau/digital-wip for improved dbpsk and dqpsk
receivers
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3946 221aa14e-8319-0410-a670-987f0aec2ac5
---
.../src/python/gnuradio/blksimpl/dbpsk.py | 32 ++++++++++++++--------
.../src/python/gnuradio/blksimpl/dqpsk.py | 16 +++++++----
gnuradio-core/src/python/gnuradio/packet_utils.py | 2 +-
3 files changed, 31 insertions(+), 19 deletions(-)
(limited to 'gnuradio-core/src/python')
diff --git a/gnuradio-core/src/python/gnuradio/blksimpl/dbpsk.py b/gnuradio-core/src/python/gnuradio/blksimpl/dbpsk.py
index 7df4f240c5..e0c0054a69 100644
--- a/gnuradio-core/src/python/gnuradio/blksimpl/dbpsk.py
+++ b/gnuradio-core/src/python/gnuradio/blksimpl/dbpsk.py
@@ -39,7 +39,7 @@ _def_gray_code = True
_def_verbose = False
_def_log = False
-_def_costas_alpha = 0.05
+_def_costas_alpha = 0.00
_def_gain_mu = 0.03
_def_mu = 0.05
_def_omega_relative_limit = 0.005
@@ -241,10 +241,12 @@ class dbpsk_demod(gr.hier_block):
# Costas loop (carrier tracking)
- # FIXME: need to decide how to handle this more generally; do we pull it from higher layer?
- costas_order = 2
- beta = .25 * self._costas_alpha * self._costas_alpha
- self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.002, -0.002, costas_order)
+ # The Costas loop is not needed for BPSK, though it can help. Turn the Costas loop on
+ # by setting an alpha value of something greater than 0 (e.g., 0.1)
+ if self._costas_alpha > 0.0:
+ costas_order = 2
+ beta = .25 * self._costas_alpha * self._costas_alpha
+ self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.002, -0.002, costas_order)
# RRC data filter
ntaps = 11 * self._samples_per_symbol
@@ -289,9 +291,14 @@ class dbpsk_demod(gr.hier_block):
self._setup_logging()
# Connect and Initialize base class
- self._fg.connect(self.pre_scaler, self.agc, self.costas_loop,
- self.rrc_filter, self.clock_recovery, self.diffdec,
- self.slicer, self.symbol_mapper, self.unpack)
+ if self._costas_alpha > 0.0: # With Costas Loop
+ self._fg.connect(self.pre_scaler, self.agc, self.costas_loop,
+ self.rrc_filter, self.clock_recovery, self.diffdec,
+ self.slicer, self.symbol_mapper, self.unpack)
+ else: # Without Costas Loop
+ self._fg.connect(self.pre_scaler, self.agc,
+ self.rrc_filter, self.clock_recovery, self.diffdec,
+ self.slicer, self.symbol_mapper, self.unpack)
gr.hier_block.__init__(self, self._fg, self.pre_scaler, self.unpack)
@@ -317,10 +324,11 @@ class dbpsk_demod(gr.hier_block):
gr.file_sink(gr.sizeof_gr_complex, "prescaler.dat"))
self._fg.connect(self.agc,
gr.file_sink(gr.sizeof_gr_complex, "agc.dat"))
- self._fg.connect(self.costas_loop,
- gr.file_sink(gr.sizeof_gr_complex, "costas_loop.dat"))
- self._fg.connect((self.costas_loop,1),
- gr.file_sink(gr.sizeof_gr_complex, "costas_error.dat"))
+ if self._costas_alpha > 0.0:
+ self._fg.connect(self.costas_loop,
+ gr.file_sink(gr.sizeof_gr_complex, "costas_loop.dat"))
+ self._fg.connect((self.costas_loop,1),
+ gr.file_sink(gr.sizeof_gr_complex, "costas_error.dat"))
self._fg.connect(self.rrc_filter,
gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat"))
self._fg.connect(self.clock_recovery,
diff --git a/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py b/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
index 3b60f2242e..88b3f1e73c 100644
--- a/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
+++ b/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
@@ -39,7 +39,7 @@ _def_gray_code = True
_def_verbose = False
_def_log = False
-_def_costas_alpha = 0.10
+_def_costas_alpha = 0.0
_def_gain_mu = 0.03
_def_mu = 0.05
_def_omega_relative_limit = 0.005
@@ -238,11 +238,15 @@ class dqpsk_demod(gr.hier_block):
self.agc = gr.feedforward_agc_cc(16, 1.0)
# Costas loop (carrier tracking)
- # FIXME: need to decide how to handle this more generally; do we pull it from higher layer?
- costas_order = 4
- beta = .25 * self._costas_alpha * self._costas_alpha
- #self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.1, -0.1, costas_order)
- self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.002, -0.002, costas_order)
+ if self._costas_alpha == 0.0: # If no alpha value was specified by the user
+ alpha_dir = {2:0.075, 3:0.075, 4:0.105, 5:0.105, 6:0.125, 7:0.130}
+ self._costas_alpha = alpha_dir[self._samples_per_symbol]
+
+ costas_order = 4
+ # The value of beta is now set to be overdamped; this value can have a huge impact on the
+ # performance of QPSK. Set to 0.25 for critically damped or higher for underdamped responses.
+ beta = .15 * self._costas_alpha * self._costas_alpha
+ self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.02, -0.02, costas_order)
# RRC data filter
ntaps = 11 * samples_per_symbol
diff --git a/gnuradio-core/src/python/gnuradio/packet_utils.py b/gnuradio-core/src/python/gnuradio/packet_utils.py
index 1dab48ab42..59b1353662 100644
--- a/gnuradio-core/src/python/gnuradio/packet_utils.py
+++ b/gnuradio-core/src/python/gnuradio/packet_utils.py
@@ -72,7 +72,7 @@ def conv_1_0_string_to_packed_binary_string(s):
default_access_code = \
conv_packed_binary_string_to_1_0_string('\xAC\xDD\xA4\xE2\xF2\x8C\x20\xFC')
preamble = \
- conv_packed_binary_string_to_1_0_string('\xAA\xAA\xAA\xAB')
+ conv_packed_binary_string_to_1_0_string('\x6C\xC6\x6C\xC6\x6C\xC6\x6C\xC6')
def is_1_0_string(s):
if not isinstance(s, str):
--
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