1 files changed, 95 insertions, 0 deletions
diff --git a/gr-dtv/lib/atsc/atsc_fpll_impl.cc b/gr-dtv/lib/atsc/atsc_fpll_impl.cc
new file mode 100644
index 0000000000..b211f80d6e
--- /dev/null
+++ b/gr-dtv/lib/atsc/atsc_fpll_impl.cc
@@ -0,0 +1,95 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2014 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "atsc_fpll_impl.h"
+#include <gnuradio/io_signature.h>
+#include <gnuradio/math.h>
+#include <gnuradio/sincos.h>
+
+namespace gr {
+  namespace dtv {
+
+    atsc_fpll::sptr
+    atsc_fpll::make(float rate)
+    {
+      return gnuradio::get_initial_sptr
+	(new atsc_fpll_impl(rate));
+    }
+
+    atsc_fpll_impl::atsc_fpll_impl(float rate)
+      : sync_block("dtv_atsc_fpll",
+                   io_signature::make(1, 1, sizeof(gr_complex)),
+                   io_signature::make(1, 1, sizeof(float)))
+    {
+      d_afc.set_taps(1.0-exp(-1.0/rate/5e-6));
+      d_nco.set_freq((-3e6 + 0.309e6)/rate*2*M_PI);
+      d_nco.set_phase(0.0);
+    }
+
+    atsc_fpll_impl::~atsc_fpll_impl()
+    {
+    }
+
+    int
+    atsc_fpll_impl::work(int noutput_items,
+                         gr_vector_const_void_star &input_items,
+                         gr_vector_void_star &output_items)
+    {
+      const gr_complex *in = (const gr_complex *)input_items[0];
+      float *out = (float *)output_items[0];
+
+      for (int k = 0; k < noutput_items; k++) {
+        float a_cos, a_sin;
+
+        d_nco.step();                  // increment phase
+        d_nco.sincos(&a_sin, &a_cos);  // compute cos and sin
+
+        // Mix out carrier and output I-only signal
+        gr_complex result = in[k]*gr_complex(a_sin, a_cos);
+        out[k] = result.real();
+
+        // Update phase/freq error
+        gr_complex filtered = d_afc.filter(result);
+        float x = gr::fast_atan2f(filtered.imag(), filtered.real());
+
+        // avoid slamming filter with big transitions
+        static const float limit = M_PI/2.0;
+        if (x > limit)
+          x = limit;
+        else if (x < -limit)
+          x = -limit;
+
+        static const float alpha = 0.0002;
+        static const float beta = alpha*alpha/4.0;
+        d_nco.adjust_phase(alpha*x);
+        d_nco.adjust_freq(beta*x);
+      }
+
+      return noutput_items;
+    }
+
+  } /* namespace dtv */
+} /* namespace gr */