Merge commit 'v3.3.0' into upstream

[debian/gnuradio] / gr-atsc / src / lib / atsci_root_raised_cosine_bandpass.cc

diff --git a/gr-atsc/src/lib/atsci_root_raised_cosine_bandpass.cc b/gr-atsc/src/lib/atsci_root_raised_cosine_bandpass.cc
new file mode 100644 (file)
index 0000000..a7c427d
--- /dev/null
+++ b/gr-atsc/src/lib/atsci_root_raised_cosine_bandpass.cc
@@ -0,0 +1,51 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2002 Free Software Foundation, Inc.
+ * 
+ * This file is part of GNU Radio
+ * 
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ * 
+ * GNU Radio is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include <atsci_root_raised_cosine_bandpass.h>
+#include <iostream>
+#include <cmath>
+
+using std::vector;
+using std::cerr;
+using std::endl;
+
+
+vector<float> 
+atsc_root_raised_cosine_bandpass::taps (double sampling_freq)
+{
+
+  vector<float> t = atsc_root_raised_cosine::taps (sampling_freq);
+
+  cerr << "atsc_root_raised_cosine_bandpass::taps -- " << t.size () << endl;
+
+  // heterodyne the low pass coefficients up to the specified bandpass 
+  // center frequency.  Note that when we do this, the filter bandwidth
+  // is effectively twice the low pass (2.69 * 2 = 5.38) and hence
+  // matches the diagram in the ATSC spec.
+
+  double arg = 2 * M_PI * _center_freq / sampling_freq;
+  for (unsigned int i = 0; i < t.size (); i++)
+    // the factor of 2 keeps the gain of the passband normalized to 1
+    t[i] *= 2 * cos (arg * (double) i);
+
+  return t;
+}