gr-noaa: Switched to 'double rate BPSK' HRPT synchronization

[debian/gnuradio] / gr-noaa / lib / noaa_hrpt_bit_sync.cc

diff --git a/gr-noaa/lib/noaa_hrpt_bit_sync.cc b/gr-noaa/lib/noaa_hrpt_bit_sync.cc
new file mode 100644 (file)
index 0000000..53e47d9
--- /dev/null
+++ b/gr-noaa/lib/noaa_hrpt_bit_sync.cc
@@ -0,0 +1,72 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2009 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 <noaa_hrpt_bit_sync.h>
+#include <gr_io_signature.h>
+#include <iostream>
+
+noaa_hrpt_bit_sync_sptr
+noaa_make_hrpt_bit_sync()
+{
+  return gnuradio::get_initial_sptr(new noaa_hrpt_bit_sync());
+}
+
+noaa_hrpt_bit_sync::noaa_hrpt_bit_sync()
+  : gr_block("noaa_hrpt_bit_sync",
+            gr_make_io_signature(1, 1, sizeof(char)),
+            gr_make_io_signature(1, 1, sizeof(char))),
+    d_mid_bit(true),
+    d_last_bit(0)
+{
+}
+
+int
+noaa_hrpt_bit_sync::general_work(int noutput_items,
+                                gr_vector_int &ninput_items,
+                                gr_vector_const_void_star &input_items,
+                                gr_vector_void_star &output_items)
+{
+  int ninputs = ninput_items[0];
+  const char *in = (const char *)input_items[0];
+  char *out = (char *)output_items[0];
+
+  int i = 0, j = 0;
+  while (i < ninputs && j < noutput_items) {
+    char bit = in[i++];
+    char diff = bit^d_last_bit;
+    d_last_bit = bit;
+
+    if (d_mid_bit && diff) {
+      out[j++] = bit;
+      d_mid_bit = false;
+    }
+    else
+      d_mid_bit = true;
+  }
+
+  consume_each(i);
+  return j;
+}