[Commit-gnuradio] r3945 - gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl

[trondeau]

Author: trondeau
Date: 2006-11-05 13:56:09 -0700 (Sun, 05 Nov 2006)
New Revision: 3945

Modified:
   
gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
Log:
adjusted Costas gain values for different SPS; user can override these defaults

Modified: 
gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
===================================================================
--- 
gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
       2006-11-05 19:42:19 UTC (rev 3944)
+++ 
gnuradio/branches/developers/trondeau/digital-wip/gnuradio-core/src/python/gnuradio/blksimpl/dqpsk.py
       2006-11-05 20:56:09 UTC (rev 3945)
@@ -39,7 +39,7 @@
 _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 @@
         self.agc = gr.feedforward_agc_cc(16, 1.0)
        
         # Costas loop (carrier tracking)
-        costas_order = 4
+        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 = .10 * self._costas_alpha * self._costas_alpha
-        self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.002, 
-0.002, costas_order)
+        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