--- /dev/null
+/* -*- 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.
+ */
+#ifndef _ATSC_SYNC_TAG_H_
+#define _ATSC_SYNC_TAG_H_
+
+/*
+ * Constants used to communicate in the second stream passed between
+ * GrAtscFSCorrelator, GrAtscEqualizer and GrAtscFieldSyncMux. The
+ * second stream is sample-for-sample parallel with the streaming
+ * floating point in the first stream. The second stream provides
+ * information about alignment boundaries.
+ *
+ * These are in floating point because the current implementation
+ * requires that for a given module, all input streams share the same
+ * type and all output streams share the same type. We'd use unsigned
+ * char otherwise.
+ */
+
+namespace atsc_sync_tag {
+
+ // Nothing special
+ static const float NORMAL = 0.0;
+
+ // The corresponding symbol is the first symbol of the
+ // data segment sync sequence { +5, -5, -5, +5 }
+ static const float START_SEG_SYNC = 1.0;
+
+ // The corresponding symbol is the first symbol of the
+ // field sync 1 PN511 pattern.
+ static const float START_FIELD_SYNC_1 = 2.0;
+
+ // The corresponding symbol is the first symbol of the
+ // field sync 2 PN511 pattern.
+ static const float START_FIELD_SYNC_2 = 3.0;
+};
+
+#endif /* _ATSC_SYNC_TAG_H_ */