Imported Upstream version 3.2.2

[debian/gnuradio] / gnuradio-core / src / lib / general / gr_costas_loop_cc.h

diff --git a/gnuradio-core/src/lib/general/gr_costas_loop_cc.h b/gnuradio-core/src/lib/general/gr_costas_loop_cc.h
index 56cbbeacf0330d99dd0afc79d374a90657c4a59f..3b4aab86c0d89d06a8bc29df49660787aa940f36 100644 (file)
--- a/gnuradio-core/src/lib/general/gr_costas_loop_cc.h
+++ b/gnuradio-core/src/lib/general/gr_costas_loop_cc.h
@@ -28,9 +28,35 @@
 #include <stdexcept>
 #include <fstream>
 
+
+/*! \brief A Costas loop carrier recovery module.
+ * \ingroup sync_blk
+ *  
+ *  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
+ *  
+ * \param alpha the loop gain used for phase adjustment
+ * \param beta the loop gain for frequency adjustments
+ * \param max_freq the maximum frequency deviation (radians/sample) the loop can handle
+ * \param min_freq the minimum frequency deviation (radians/sample) the loop can handle
+ * \param order the loop order, either 2 or 4
+ */
 class gr_costas_loop_cc;
 typedef boost::shared_ptr<gr_costas_loop_cc> gr_costas_loop_cc_sptr;
 
+
 gr_costas_loop_cc_sptr 
 gr_make_costas_loop_cc (float alpha, float beta,
                        float max_freq, float min_freq, 
@@ -40,7 +66,11 @@ gr_make_costas_loop_cc (float alpha, float beta,
 
 /*!
  * \brief Carrier tracking PLL for QPSK
+ * \ingroup sync_blk
  * input: complex; output: complex
+ * <br>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
  *
  * \p order must be 2 or 4.
  */
@@ -59,15 +89,51 @@ class gr_costas_loop_cc : public gr_sync_block
                     int order
                     ) throw (std::invalid_argument);
 
+  /*! \brief the phase detector circuit for fourth-order loops
+   *  \param sample complex sample
+   *  \return the phase error
+   */
   float phase_detector_4(gr_complex sample) const;    // for QPSK
+
+  /*! \brief the phase detector circuit for second-order loops
+   *  \param sample a complex sample
+   *  \return the phase error
+   */
   float phase_detector_2(gr_complex sample) const;    // for BPSK
+
+
   float (gr_costas_loop_cc::*d_phase_detector)(gr_complex sample) const;
 
 public:
 
+  /*! \brief set the first order gain
+   *  \param alpha
+   */
+  void set_alpha(float alpha);
+
+  /*! \brief get the first order gain
+   * 
+   */
+  float alpha() const { return d_alpha; }
+  
+  /*! \brief set the second order gain
+   *  \param beta
+   */
+  void set_beta(float beta);
+
+  /*! \brief get the second order gain
+   * 
+   */
+  float beta() const { return d_beta; }
+  
   int work (int noutput_items,
            gr_vector_const_void_star &input_items,
            gr_vector_void_star &output_items);
+
+  /*! \brief returns the current NCO frequency in radians/sample
+   *
+   */
+  float freq() const { return d_freq; }
 };
 
 #endif