1 files changed, 78 insertions, 0 deletions
diff --git a/gr-digital/include/gnuradio/digital/costas_loop_cc.h b/gr-digital/include/gnuradio/digital/costas_loop_cc.h
new file mode 100644
index 0000000000..38a41a5db5
--- /dev/null
+++ b/gr-digital/include/gnuradio/digital/costas_loop_cc.h
@@ -0,0 +1,78 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2006,2011,2012 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 INCLUDED_DIGITAL_COSTAS_LOOP_CC_H
+#define INCLUDED_DIGITAL_COSTAS_LOOP_CC_H
+
+#include <gnuradio/digital/api.h>
+#include <gnuradio/blocks/control_loop.h>
+#include <gnuradio/sync_block.h>
+
+namespace gr {
+  namespace digital {
+
+    /*! 
+     * \brief A Costas loop carrier recovery module.
+     * \ingroup synchronizers_blk
+     *
+     * \details
+     * The Costas loop locks to the center frequency of a signal and
+     * downconverts it to baseband. The second (order=2) order loop
+     * is used for BPSK where the real part of the output signal is
+     * the baseband BPSK signal and the imaginary part is the error
+     * signal. When order=4, it can be used for quadrature
+     * modulations where both I and Q (real and imaginary) are
+     * outputted.
+     *
+     * More details can be found online:
+     *
+     * J. Feigin, "Practical Costas loop design: Designing a simple
+     * and inexpensive BPSK Costas loop carrier recovery circuit," RF
+     * signal processing, pp. 20-36, 2002.
+     *
+     * http://rfdesign.com/images/archive/0102Feigin20.pdf
+     *  
+     * The Costas loop can have two output streams:
+     *    stream 1 is the baseband I and Q;
+     *    stream 2 is the normalized frequency of the loop
+     */
+    class DIGITAL_API costas_loop_cc
+      : virtual public sync_block, 
+        virtual public blocks::control_loop
+    {
+    public:
+      // gr::digital::costas_loop_cc::sptr
+      typedef boost::shared_ptr<costas_loop_cc> sptr;
+
+      /*! 
+       * Make a Costas loop carrier recovery block.
+       *
+       * \param loop_bw  internal 2nd order loop bandwidth (~ 2pi/100)
+       * \param order the loop order, either 2, 4, or 8
+       */
+      static sptr make(float loop_bw, int order);
+    };
+
+  } /* namespace digital */
+} /* namespace gr */
+
+#endif /* INCLUDED_DIGITAL_COSTAS_LOOP_CC_H */