1 files changed, 106 insertions, 0 deletions
diff --git a/gr-atsc/src/lib/GrAtscBitTimingLoop3.cc b/gr-atsc/src/lib/GrAtscBitTimingLoop3.cc
new file mode 100644
index 0000000000..2b21f2f0ac
--- /dev/null
+++ b/gr-atsc/src/lib/GrAtscBitTimingLoop3.cc
@@ -0,0 +1,106 @@
+/* -*- 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 2, 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <GrAtscBitTimingLoop3.h>
+#include <cmath>
+#include <cstdio>
+#include <assert.h>
+
+using std::abs;
+
+
+static const int NOUTPUTS = 2;
+
+GrAtscBitTimingLoop3::GrAtscBitTimingLoop3 (double ratio_of_rx_clock_to_symbol_freq)
+  : VrDecimatingSigProc<float,float> (NOUTPUTS, (int) rint (ratio_of_rx_clock_to_symbol_freq)),
+    d_interp (ratio_of_rx_clock_to_symbol_freq), d_next_input(0),
+    d_rx_clock_to_symbol_freq (ratio_of_rx_clock_to_symbol_freq)
+
+{
+  assert (ratio_of_rx_clock_to_symbol_freq >= 1.8);	// sanity check
+  
+  history = 1500;  	// spare input samples in case we need them.
+}
+
+//
+// We are nominally a 2x decimator, but our actual rate varies slightly
+// depending on the difference between the transmitter and receiver
+// sampling clocks.  Hence, we need to compute our input ranges
+// explictly.
+
+int
+GrAtscBitTimingLoop3::forecast(VrSampleRange output,
+			       VrSampleRange inputs[]) {
+  assert (numberInputs == 1);
+  
+  /* dec:1 ratio with history */
+  inputs[0].index = d_next_input;
+  inputs[0].size =
+    ((unsigned long) (output.size * d_rx_clock_to_symbol_freq) + history - 1);
+
+  return 0;
+}  
+
+
+int 
+GrAtscBitTimingLoop3::work (VrSampleRange output, void *ao[],
+			    VrSampleRange inputs[], void *ai[])
+{
+  iType	 *in = ((iType **)ai)[0];
+  oDataType *out_sample = ((oDataType **)ao)[0];
+  oTagType  *out_tag =    ((oTagType **) ao)[1];
+
+  // Force in-order computation of output stream.
+  // This is required because of our slightly variable decimation factor
+  sync (output.index);
+
+  // We are tasked with producing output.size output samples.  
+  // We will consume approximately 2 * output.size input samples.
+
+  int		si = 0;		// source index
+  unsigned int	k;		// output index
+
+  float		interp_sample;
+  int		symbol_index;
+  double	timing_adjustment = 0;
+  bool		seg_locked;
+  oTagType	tag;
+
+  memset (&tag, 0, sizeof (tag));
+
+  for (k = 0; k < output.size; k++){
+
+    if (!d_interp.update (in, inputs[0].size, &si, timing_adjustment, &interp_sample)){
+      fprintf (stderr, "GrAtscBitTimingLoop3: ran short on data...\n");
+      break;
+    }
+      
+    d_sssr.update (interp_sample, &seg_locked, &symbol_index, &timing_adjustment);
+    out_sample[k] = interp_sample;
+    tag.valid = seg_locked;
+    tag.symbol_num = symbol_index;
+    out_tag[k] = tag;
+  }
+
+  d_next_input += si;	// update next_input so forecast can get us what we need
+  return k;
+}