[Commit-gnuradio] [gnuradio] 11/13: filter: fixed default filter for rational_resampler.

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commit 464f23ae4eba3230c54b68d783a3ab7b4734744c
Author: Tom Rondeau <address@hidden>
Date:   Tue Dec 2 18:01:41 2014 -0500

    filter: fixed default filter for rational_resampler.
    
    Addresses issue #745. When rate < 1 (downsampling), take into account the 
amount of downsampling (decimation) and adjust the LPF's passband to reduce 
aliasing.
---
 gr-digital/lib/constellation.cc                    |  2 +-
 .../digital/qa_constellation_soft_decoder_cf.py    |  2 +-
 gr-digital/python/digital/soft_dec_lut_gen.py      |  2 +-
 gr-filter/python/filter/rational_resampler.py      | 33 ++++++++++++++--------
 4 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/gr-digital/lib/constellation.cc b/gr-digital/lib/constellation.cc
index b17635f..a477aa8 100644
--- a/gr-digital/lib/constellation.cc
+++ b/gr-digital/lib/constellation.cc
@@ -1,6 +1,6 @@
 /* -*- c++ -*- */
 /*
- * Copyright 2010-2012 Free Software Foundation, Inc.
+ * Copyright 2010-2012,2014 Free Software Foundation, Inc.
  *
  * This file is part of GNU Radio
  *
diff --git a/gr-digital/python/digital/qa_constellation_soft_decoder_cf.py 
b/gr-digital/python/digital/qa_constellation_soft_decoder_cf.py
index 448e76e..872aed0 100644
--- a/gr-digital/python/digital/qa_constellation_soft_decoder_cf.py
+++ b/gr-digital/python/digital/qa_constellation_soft_decoder_cf.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 #
-# Copyright 2013 Free Software Foundation, Inc.
+# Copyright 2013-2014 Free Software Foundation, Inc.
 #
 # This file is part of GNU Radio
 #
diff --git a/gr-digital/python/digital/soft_dec_lut_gen.py 
b/gr-digital/python/digital/soft_dec_lut_gen.py
index 9c184d6..5bea27f 100644
--- a/gr-digital/python/digital/soft_dec_lut_gen.py
+++ b/gr-digital/python/digital/soft_dec_lut_gen.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 #
-# Copyright 2013 Free Software Foundation, Inc.
+# Copyright 2013-2014 Free Software Foundation, Inc.
 #
 # This file is part of GNU Radio
 #
diff --git a/gr-filter/python/filter/rational_resampler.py 
b/gr-filter/python/filter/rational_resampler.py
index 8f1dc36..32246a0 100644
--- a/gr-filter/python/filter/rational_resampler.py
+++ b/gr-filter/python/filter/rational_resampler.py
@@ -40,16 +40,25 @@ def design_filter(interpolation, decimation, fractional_bw):
     if fractional_bw >= 0.5 or fractional_bw <= 0:
         raise ValueError, "Invalid fractional_bandwidth, must be in (0, 0.5)"
 
-    beta = 5.0
-    trans_width = 0.5 - fractional_bw
-    mid_transition_band = 0.5 - trans_width/2
-
+    beta = 7.0
+    halfband = 0.5
+    rate = float(interpolation)/float(decimation)
+    if(rate >= 1.0):
+        trans_width = halfband - fractional_bw
+        mid_transition_band = halfband - trans_width/2.0
+    else:
+        trans_width = rate*(halfband - fractional_bw)
+        mid_transition_band = rate*halfband - trans_width/2.0
+
+    print trans_width, mid_transition_band
     taps = filter.firdes.low_pass(interpolation,                     # gain
-                                  1,                                 # Fs
-                                  mid_transition_band/interpolation, # trans 
mid point
-                                  trans_width/interpolation,         # 
transition width
+                                  interpolation,                     # Fs
+                                  mid_transition_band,               # trans 
mid point
+                                  trans_width,                       # 
transition width
                                   filter.firdes.WIN_KAISER,
                                   beta)                              # beta
+
+    print len(taps)
     return taps
 
 
@@ -90,13 +99,15 @@ class _rational_resampler_base(gr.hier_block2):
         if taps is None:
             taps = design_filter(interpolation, decimation, fractional_bw)
 
-        resampler = resampler_base(interpolation, decimation, taps)
+        self.resampler = resampler_base(interpolation, decimation, taps)
        gr.hier_block2.__init__(self, "rational_resampler",
-                               gr.io_signature(1, 1, 
resampler.input_signature().sizeof_stream_item(0)),
-                               gr.io_signature(1, 1, 
resampler.output_signature().sizeof_stream_item(0)))
+                               gr.io_signature(1, 1, 
self.resampler.input_signature().sizeof_stream_item(0)),
+                               gr.io_signature(1, 1, 
self.resampler.output_signature().sizeof_stream_item(0)))
 
-       self.connect(self, resampler, self)
+       self.connect(self, self.resampler, self)
 
+    def taps(self):
+        return self.resampler.taps()
 
 class rational_resampler_fff(_rational_resampler_base):
     def __init__(self, interpolation, decimation, taps=None, 
fractional_bw=None):