From dbff43ebe7be502e7f2b2cb4e09152c82a669167 Mon Sep 17 00:00:00 2001
From: trondeau <trondeau@221aa14e-8319-0410-a670-987f0aec2ac5>
Date: Tue, 21 Nov 2006 17:21:15 +0000
Subject: improved Costas loop gains for QPSK receiver
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@4009 221aa14e-8319-0410-a670-987f0aec2ac5
---
gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
(limited to 'gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py')
diff --git a/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py b/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
index 9459f42433..0563840ff0 100644
--- a/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
+++ b/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
@@ -239,13 +239,13 @@ class dqpsk_demod(gr.hier_block):
# Costas loop (carrier tracking)
if self._costas_alpha is None: # 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}
+ alpha_dir = {2:0.075, 3:0.09, 4:0.09, 5:0.095, 6:0.10, 7:0.105}
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
+ # The value of beta is now set to be underdamped; 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
+ beta = .5 0 * 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
--
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