Merge branch 'digital' of https://github.com/trondeau/gnuradio into digital

Conflicts:
	gnuradio-core/src/lib/filter/gr_pfb_clock_sync_ccf.h
	gnuradio-core/src/lib/general/gr_fll_band_edge_cc.h
	gnuradio-core/src/lib/general/gr_pll_refout_cc.h
	gr-digital/lib/digital_constellation_receiver_cb.cc
	gr-digital/lib/digital_constellation_receiver_cb.h
	gr-digital/lib/digital_costas_loop_cc.h

12 files changed, 473 insertions, 432 deletions

diff --git a/gnuradio-core/src/lib/general/CMakeLists.txt b/gnuradio-core/src/lib/general/CMakeLists.txt
index b2182eb90..1cd9c6bd1 100644
--- a/gnuradio-core/src/lib/general/CMakeLists.txt
+++ b/gnuradio-core/src/lib/general/CMakeLists.txt
@@ -77,6 +77,7 @@ LIST(APPEND gnuradio_core_sources
     ${CMAKE_CURRENT_SOURCE_DIR}/gr_reverse.cc
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_add_const_ss_generic.cc
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_char_to_float.cc
+    ${CMAKE_CURRENT_SOURCE_DIR}/gri_control_loop.cc
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_debugger_hook.cc
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_fft.cc
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_float_to_char.cc
@@ -131,6 +132,7 @@ INSTALL(FILES
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_agc2_cc.h
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_agc2_ff.h
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_char_to_float.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/gri_control_loop.h
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_debugger_hook.h
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_fft.h
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_float_to_char.h
@@ -160,6 +162,7 @@ INSTALL(FILES
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_agc_ff.i
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_agc2_cc.i
     ${CMAKE_CURRENT_SOURCE_DIR}/gri_agc2_ff.i
+    ${CMAKE_CURRENT_SOURCE_DIR}/gri_control_loop.i
     DESTINATION ${GR_INCLUDE_DIR}/gnuradio/swig
     COMPONENT "core_swig"
 )
@@ -201,7 +204,6 @@ SET(gr_core_general_triple_threats
     gr_fft_vcc
     gr_fft_vfc
     gr_firdes
-    gr_fll_band_edge_cc
     gr_float_to_char
     gr_float_to_complex
     gr_float_to_short
diff --git a/gnuradio-core/src/lib/general/Makefile.am b/gnuradio-core/src/lib/general/Makefile.am
index e63d8930b..f210cee39 100644
--- a/gnuradio-core/src/lib/general/Makefile.am
+++ b/gnuradio-core/src/lib/general/Makefile.am
@@ -72,7 +72,6 @@ libgeneral_la_SOURCES = 		\
 	gr_fft_vcc_fftw.cc		\
 	gr_fft_vfc.cc			\
 	gr_firdes.cc			\
-	gr_fll_band_edge_cc.cc		\
 	gr_float_to_char.cc		\
 	gr_float_to_complex.cc		\
 	gr_float_to_short.cc		\
@@ -154,6 +153,7 @@ libgeneral_la_SOURCES = 		\
 	gr_wvps_ff.cc			\
 	gri_add_const_ss_generic.cc	\
 	gri_char_to_float.cc		\
+	gri_control_loop.cc		\
 	gri_debugger_hook.cc		\
 	gri_fft.cc			\
 	gri_float_to_char.cc		\
@@ -220,7 +220,6 @@ grinclude_HEADERS = 			\
 	gr_fft_vcc_fftw.h		\
 	gr_fft_vfc.h			\
 	gr_firdes.h			\
-	gr_fll_band_edge_cc.h		\
 	gr_float_to_char.h		\
 	gr_float_to_complex.h		\
 	gr_float_to_short.h		\
@@ -314,6 +313,7 @@ grinclude_HEADERS = 			\
 	gri_agc2_cc.h			\
 	gri_agc2_ff.h			\
 	gri_char_to_float.h		\
+	gri_control_loop.h		\
 	gri_debugger_hook.h		\
 	gri_fft.h			\
 	gri_float_to_char.h		\
@@ -382,7 +382,6 @@ swiginclude_HEADERS =			\
 	gr_fft_vcc.i			\
 	gr_fft_vfc.i			\
 	gr_firdes.i			\
-	gr_fll_band_edge_cc.i		\
 	gr_float_to_char.i		\
 	gr_float_to_complex.i		\
 	gr_float_to_short.i		\
@@ -463,6 +462,7 @@ swiginclude_HEADERS =			\
 	gri_agc_ff.i			\
 	gri_agc2_cc.i			\
 	gri_agc2_ff.i			\
+	gri_control_loop.i		\
 	gr_descrambler_bb.i		\
 	gr_scrambler_bb.i		\
 	gr_probe_mpsk_snr_c.i		\
diff --git a/gnuradio-core/src/lib/general/general.i b/gnuradio-core/src/lib/general/general.i
index c43622400..f9adff3fa 100644
--- a/gnuradio-core/src/lib/general/general.i
+++ b/gnuradio-core/src/lib/general/general.i
@@ -22,6 +22,7 @@
 
 %{
 
+#include <gri_control_loop.h>
 #include <gr_nop.h>
 #include <gr_null_sink.h>
 #include <gr_null_source.h>
@@ -131,7 +132,6 @@
 #include <gr_wavelet_ff.h>
 #include <gr_wvps_ff.h>
 #include <gr_copy.h>
-#include <gr_fll_band_edge_cc.h>
 #include <gr_additive_scrambler_bb.h>
 #include <complex_vec_test.h>
 #include <gr_annotator_alltoall.h>
@@ -139,6 +139,7 @@
 #include <gr_burst_tagger.h>
 %}
 
+%include "gri_control_loop.i"
 %include "gr_nop.i"
 %include "gr_null_sink.i"
 %include "gr_null_source.i"
@@ -248,7 +249,6 @@
 %include "gr_wavelet_ff.i"
 %include "gr_wvps_ff.i"
 %include "gr_copy.i"
-%include "gr_fll_band_edge_cc.i"
 %include "gr_additive_scrambler_bb.i"
 %include "complex_vec_test.i"
 %include "gr_annotator_alltoall.i"
diff --git a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.cc b/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.cc
deleted file mode 100644
index c32398e6d..000000000
--- a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.cc
+++ /dev/null
@@ -1,214 +0,0 @@
-/* -*- c++ -*- */
-/*
- * Copyright 2009,2010 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 <gr_fll_band_edge_cc.h>
-#include <gr_fir_ccc.h>
-#include <gr_fir_util.h>
-#include <gri_fft.h>
-#include <gr_io_signature.h>
-#include <gr_expj.h>
-#include <gr_math.h>
-#include <cstdio>
-
-#define M_TWOPI (2*M_PI)
-
-float sinc(float x)
-{
-  if(x == 0)
-    return 1;
-  else
-    return sin(M_PI*x)/(M_PI*x);
-}
-  
-
-
-gr_fll_band_edge_cc_sptr gr_make_fll_band_edge_cc (float samps_per_sym, float rolloff,
-						   int filter_size, float gain_alpha, float gain_beta)
-{
-  return gnuradio::get_initial_sptr(new gr_fll_band_edge_cc (samps_per_sym, rolloff,
-							    filter_size, gain_alpha, gain_beta));
-}
-
-
-static int ios[] = {sizeof(gr_complex), sizeof(float), sizeof(float), sizeof(gr_complex)};
-static std::vector<int> iosig(ios, ios+sizeof(ios)/sizeof(int));
-gr_fll_band_edge_cc::gr_fll_band_edge_cc (float samps_per_sym, float rolloff,
-					  int filter_size, float alpha, float beta)
-  : gr_sync_block ("fll_band_edge_cc",
-		   gr_make_io_signature (1, 1, sizeof(gr_complex)),
-		   gr_make_io_signaturev (1, 4, iosig)),
-    d_alpha(alpha), d_beta(beta), d_updated (false)
-{
-  // base this on the number of samples per symbol
-  d_max_freq =  M_TWOPI * (2.0/samps_per_sym);
-  d_min_freq = -M_TWOPI * (2.0/samps_per_sym);
-
-  d_freq = 0;
-  d_phase = 0;
-
-  set_alpha(alpha);
-
-  design_filter(samps_per_sym, rolloff, filter_size);
-}
-
-gr_fll_band_edge_cc::~gr_fll_band_edge_cc ()
-{
-  delete d_filter_lower;
-  delete d_filter_upper;
-}
-
-void
-gr_fll_band_edge_cc::set_alpha(float alpha) 
-{ 
-  //float eta = sqrt(2.0)/2.0;
-  //float theta = alpha;
-  //d_alpha = (4*eta*theta) / (1.0 + 2.0*eta*theta + theta*theta);
-  //d_beta = (4*theta*theta) / (1.0 + 2.0*eta*theta + theta*theta);
-  d_alpha = alpha;
-}
-
-void
-gr_fll_band_edge_cc::design_filter(float samps_per_sym, float rolloff, int filter_size)
-{
-  int M = rint(filter_size / samps_per_sym);
-  float power = 0;
-  std::vector<float> bb_taps;
-  for(int i = 0; i < filter_size; i++) {
-    float k = -M + i*2.0/samps_per_sym;
-    float tap = sinc(rolloff*k - 0.5) + sinc(rolloff*k + 0.5);
-    power += tap;
-
-    bb_taps.push_back(tap);
-  }
-
-  int N = (bb_taps.size() - 1.0)/2.0;
-  std::vector<gr_complex> taps_lower;
-  std::vector<gr_complex> taps_upper;
-  for(unsigned int i = 0; i < bb_taps.size(); i++) {
-    float tap = bb_taps[i] / power;
-
-    float k = (-N + (int)i)/(2.0*samps_per_sym);
-    
-    gr_complex t1 = tap * gr_expj(-2*M_PI*(1+rolloff)*k);
-    gr_complex t2 = tap * gr_expj(2*M_PI*(1+rolloff)*k);
-
-    taps_lower.push_back(t1);
-    taps_upper.push_back(t2);
-  }
-
-  std::vector<gr_complex> vtaps(0, taps_lower.size());
-  d_filter_upper = gr_fir_util::create_gr_fir_ccc(vtaps);
-  d_filter_lower = gr_fir_util::create_gr_fir_ccc(vtaps);
-
-  d_filter_lower->set_taps(taps_lower);
-  d_filter_upper->set_taps(taps_upper);
-
-  d_updated = true;
-
-  // Set the history to ensure enough input items for each filter
-  set_history(filter_size+1);
-
-}
-
-void
-gr_fll_band_edge_cc::print_taps()
-{
-  unsigned int i;
-  std::vector<gr_complex> taps_upper = d_filter_upper->get_taps();
-  std::vector<gr_complex> taps_lower = d_filter_lower->get_taps();
-
-  printf("Upper Band-edge: [");
-  for(i = 0; i < taps_upper.size(); i++) {
-    printf(" %.4e + %.4ej,", taps_upper[i].real(), taps_upper[i].imag());
-  }
-  printf("]\n\n");
-
-  printf("Lower Band-edge: [");
-  for(i = 0; i < taps_lower.size(); i++) {
-    printf(" %.4e + %.4ej,", taps_lower[i].real(), taps_lower[i].imag());
-  }
-  printf("]\n\n");
-}
-
-int
-gr_fll_band_edge_cc::work (int noutput_items,
-			   gr_vector_const_void_star &input_items,
-			   gr_vector_void_star &output_items)
-{
-  const gr_complex *in  = (const gr_complex *) input_items[0];
-  gr_complex *out = (gr_complex *) output_items[0];
-
-  float *frq = NULL;
-  float *phs = NULL;
-  gr_complex *err = NULL;
-  if(output_items.size() > 2) {
-    frq = (float *) output_items[1];
-    phs = (float *) output_items[2];
-    err = (gr_complex *) output_items[3];
-  }
-
-  if (d_updated) {
-    d_updated = false;
-    return 0;		     // history requirements may have changed.
-  }
-
-  int i;
-  gr_complex nco_out;
-  gr_complex out_upper, out_lower;
-  float error;
-  float avg_k = 0.1;
-  for(i = 0; i < noutput_items; i++) {
-    nco_out = gr_expj(d_phase);
-    out[i] = in[i] * nco_out;
-
-    out_upper = (d_filter_upper->filter(&out[i]));
-    out_lower = (d_filter_lower->filter(&out[i]));
-    error = -real((out_upper + out_lower) * conj(out_upper - out_lower));
-    d_error = avg_k*error + avg_k*d_error;  // average error
-
-    d_freq = d_freq + d_beta * d_error;
-    d_phase = d_phase + d_freq + d_alpha * d_error;
-
-    if(d_phase > M_PI)
-      d_phase -= M_TWOPI;
-    else if(d_phase < -M_PI)
-      d_phase += M_TWOPI;
-
-    if (d_freq > d_max_freq)
-      d_freq = d_max_freq;
-    else if (d_freq < d_min_freq)
-      d_freq = d_min_freq;
-
-    if(output_items.size() > 2) {
-      frq[i] = d_freq;
-      phs[i] = d_phase;
-      err[i] = d_error;
-    }
-  }
-
-
-  return noutput_items;
-}
diff --git a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.h b/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.h
deleted file mode 100644
index e3007b97a..000000000
--- a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.h
+++ /dev/null
@@ -1,140 +0,0 @@
-/* -*- 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.
- */
-
-
-#ifndef INCLUDED_GR_FLL_BAND_EDGE_CC_H
-#define	INCLUDED_GR_FLL_BAND_EDGE_CC_H
-
-#include <gr_core_api.h>
-#include <gr_sync_block.h>
-
-class gr_fll_band_edge_cc;
-typedef boost::shared_ptr<gr_fll_band_edge_cc> gr_fll_band_edge_cc_sptr;
-GR_CORE_API gr_fll_band_edge_cc_sptr gr_make_fll_band_edge_cc (float samps_per_sym, float rolloff,
-						   int filter_size, float alpha, float beta);
-
-class gr_fir_ccc;
-class gri_fft_complex;
-
-/*!
- * \class gr_fll_band_edge_cc
- * \brief Frequency Lock Loop using band-edge filters
- *
- * \ingroup general
- *
- * The frequency lock loop derives a band-edge filter that covers the upper and lower bandwidths
- * of a digitally-modulated signal. The bandwidth range is determined by the excess bandwidth
- * (e.g., rolloff factor) of the modulated signal. The placement in frequency of the band-edges
- * is determined by the oversampling ratio (number of samples per symbol) and the excess bandwidth.
- * The size of the filters should be fairly large so as to average over a number of symbols.
- *
- * The FLL works by filtering the upper and lower band edges into x_u(t) and x_l(t), respectively.
- * These are combined to form cc(t) = x_u(t) + x_l(t) and ss(t) = x_u(t) - x_l(t). Combining
- * these to form the signal e(t) = Re{cc(t) \\times ss(t)^*} (where ^* is the complex conjugate)
- * provides an error signal at the DC term that is directly proportional to the carrier frequency.
- * We then make a second-order loop using the error signal that is the running average of e(t).
- *
- * In theory, the band-edge filter is the derivative of the matched filter in frequency, 
- * (H_be(f) = \\frac{H(f)}{df}. In practice, this comes down to a quarter sine wave at the point
- * of the matched filter's rolloff (if it's a raised-cosine, the derivative of a cosine is a sine).
- * Extend this sine by another quarter wave to make a half wave around the band-edges is equivalent
- * in time to the sum of two sinc functions. The baseband filter fot the band edges is therefore
- * derived from this sum of sincs. The band edge filters are then just the baseband signal
- * modulated to the correct place in frequency. All of these calculations are done in the
- * 'design_filter' function.
- *
- * Note: We use FIR filters here because the filters have to have a flat phase response over the
- * entire frequency range to allow their comparisons to be valid.
- */
-
-class GR_CORE_API gr_fll_band_edge_cc : public gr_sync_block
-{
- private:
-  /*!
-   * Build the FLL
-   * \param samps_per_sym    (float) Number of samples per symbol of signal
-   * \param rolloff          (float) Rolloff factor of signal
-   * \param filter_size      (int)   Size (in taps) of the filter
-   * \param alpha            (float) Loop gain 1
-   * \param beta             (float) Loop gain 2
-   */
-  friend GR_CORE_API gr_fll_band_edge_cc_sptr gr_make_fll_band_edge_cc (float samps_per_sym, float rolloff,
-							    int filter_size, float alpha, float beta);
-
-  float                   d_alpha;
-  float                   d_beta;
-  float                   d_max_freq;
-  float                   d_min_freq;
-
-  gr_fir_ccc*             d_filter_upper;
-  gr_fir_ccc*             d_filter_lower;
-  bool			  d_updated;
-  float                   d_error;
-  float                   d_freq;
-  float                   d_phase;
-
-  /*!
-   * Build the FLL
-   * \param samps_per_sym (float) number of samples per symbol
-   * \param rolloff (float) Rolloff (excess bandwidth) of signal filter
-   * \param filter_size (int) number of filter taps to generate
-   * \param alpha (float) Alpha gain in the control loop
-   * \param beta  (float) Beta gain in the control loop
-   */
-  gr_fll_band_edge_cc(float samps_per_sym, float rolloff,
-		      int filter_size, float alpha, float beta);
-
-public:
-  ~gr_fll_band_edge_cc ();
-  
-  /*!
-   * Design the band-edge filter based on the number of samples per symbol,
-   * filter rolloff factor, and the filter size
-   * \param samps_per_sym    (float) Number of samples per symbol of signal
-   * \param rolloff          (float) Rolloff factor of signal
-   * \param filter_size      (int)   Size (in taps) of the filter
-   */
-  void design_filter(float samps_per_sym, float rolloff, int filter_size);
-
-  /*!
-   * Set the alpha gainvalue
-   * \param alpha    (float) new gain value
-   */
-  void set_alpha(float alpha);
-
-  /*!
-   * Set the beta gain value
-   * \param beta    (float) new gain value
-   */
-  void set_beta(float beta) { d_beta = beta; }
-
-  /*!
-   * Print the taps to screen.
-   */
-  void print_taps();
-   
-  int work (int noutput_items,
-	    gr_vector_const_void_star &input_items,
-	    gr_vector_void_star &output_items);
-};
-
-#endif
diff --git a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.i b/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.i
deleted file mode 100644
index c9c792c8a..000000000
--- a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.i
+++ /dev/null
@@ -1,41 +0,0 @@
-/* -*- 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.
- */
-
-GR_SWIG_BLOCK_MAGIC(gr,fll_band_edge_cc);
-
-gr_fll_band_edge_cc_sptr gr_make_fll_band_edge_cc (float samps_per_sym, float rolloff,
-						   int filter_size, float alpha, float beta);
-
-class gr_fll_band_edge_cc : public gr_sync_block
-{
- private:
-  gr_fll_band_edge_cc (float samps_per_sym, float rolloff,
-		       int filter_size, float alpha, float beta);
-
- public:
-  ~gr_fll_band_edge_cc ();
-
-  void set_alpha (float alpha);
-  void set_beta (float beta);
-  void design_filter(float samps_per_sym, float rolloff, int filter_size);
-  void print_taps();
-};
diff --git a/gnuradio-core/src/lib/general/gr_pll_refout_cc.cc b/gnuradio-core/src/lib/general/gr_pll_refout_cc.cc
index 8a7fbf88b..8968cd3f1 100644
--- a/gnuradio-core/src/lib/general/gr_pll_refout_cc.cc
+++ b/gnuradio-core/src/lib/general/gr_pll_refout_cc.cc
@@ -1,6 +1,6 @@
 /* -*- c++ -*- */
 /*
- * Copyright 2004,2010 Free Software Foundation, Inc.
+ * Copyright 2004,2010,2011 Free Software Foundation, Inc.
  * 
  * This file is part of GNU Radio
  * 
@@ -20,8 +20,6 @@
  * Boston, MA 02110-1301, USA.
  */
 
-// WARNING: this file is machine generated.  Edits will be over written
-
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
@@ -35,18 +33,16 @@
 #define M_TWOPI (2*M_PI)
 
 gr_pll_refout_cc_sptr
-gr_make_pll_refout_cc (float alpha, float beta, float max_freq, float min_freq)
+gr_make_pll_refout_cc (float loop_bw, float max_freq, float min_freq)
 {
-  return gnuradio::get_initial_sptr(new gr_pll_refout_cc (alpha, beta, max_freq, min_freq));
+  return gnuradio::get_initial_sptr(new gr_pll_refout_cc (loop_bw, max_freq, min_freq));
 }
 
-gr_pll_refout_cc::gr_pll_refout_cc (float alpha, float beta, float max_freq, float min_freq)
+gr_pll_refout_cc::gr_pll_refout_cc (float loop_bw, float max_freq, float min_freq)
   : gr_sync_block ("pll_refout_cc",
 		   gr_make_io_signature (1, 1, sizeof (gr_complex)),
 		   gr_make_io_signature (1, 1, sizeof (gr_complex))),
-    d_alpha(alpha), d_beta(beta), 
-    d_max_freq(max_freq), d_min_freq(min_freq),
-    d_phase(0), d_freq((max_freq+min_freq)/2)
+    gri_control_loop(loop_bw, max_freq, min_freq)
 {
 }
 
@@ -84,13 +80,10 @@ gr_pll_refout_cc::work (int noutput_items,
   while (size-- > 0) {
     error = phase_detector(*iptr++,d_phase);
     
-    d_freq = d_freq + d_beta * error;
-    d_phase = mod_2pi(d_phase + d_freq + d_alpha * error);
+    advance_loop(error);
+    phase_wrap();
+    frequency_limit();
     
-    if (d_freq > d_max_freq)
-      d_freq = d_max_freq;
-    else if (d_freq < d_min_freq)
-      d_freq = d_min_freq;
     gr_sincosf(d_phase,&t_imag,&t_real);
     *optr++ = gr_complex(t_real,t_imag);
   }
diff --git a/gnuradio-core/src/lib/general/gr_pll_refout_cc.h b/gnuradio-core/src/lib/general/gr_pll_refout_cc.h
index 833ed51cc..11bce5046 100644
--- a/gnuradio-core/src/lib/general/gr_pll_refout_cc.h
+++ b/gnuradio-core/src/lib/general/gr_pll_refout_cc.h
@@ -1,6 +1,6 @@
 /* -*- c++ -*- */
 /*
- * Copyright 2004 Free Software Foundation, Inc.
+ * Copyright 2004,2011 Free Software Foundation, Inc.
  * 
  * This file is part of GNU Radio
  * 
@@ -20,19 +20,18 @@
  * Boston, MA 02110-1301, USA.
  */
 
-
-
 #ifndef INCLUDED_GR_PLL_REFOUT_CC_H
 #define INCLUDED_GR_PLL_REFOUT_CC_H
 
 #include <gr_core_api.h>
 #include <gr_sync_block.h>
+#include <gri_control_loop.h>
 
 class gr_pll_refout_cc;
 typedef boost::shared_ptr<gr_pll_refout_cc> gr_pll_refout_cc_sptr;
 
-GR_CORE_API gr_pll_refout_cc_sptr gr_make_pll_refout_cc (float alpha, float beta,
-					       float max_freq, float min_freq);
+GR_CORE_API gr_pll_refout_cc_sptr gr_make_pll_refout_cc (float loop_bw,
+					     float max_freq, float min_freq);
 /*!
  * \brief Implements a PLL which locks to the input frequency and outputs a carrier
  * \ingroup sync_blk
@@ -48,20 +47,19 @@ GR_CORE_API gr_pll_refout_cc_sptr gr_make_pll_refout_cc (float alpha, float beta
  * and beta is the frequency gain (second order, units of radians per sample per radian)
  * \sa gr_pll_freqdet_cf, gr_pll_carriertracking_cc
  */
-class GR_CORE_API gr_pll_refout_cc : public gr_sync_block
+class GR_CORE_API gr_pll_refout_cc : public gr_sync_block, public gri_control_loop
 {
-  friend GR_CORE_API gr_pll_refout_cc_sptr gr_make_pll_refout_cc (float alpha, float beta,
-							float max_freq, float min_freq);
+  friend GR_CORE_API gr_pll_refout_cc_sptr gr_make_pll_refout_cc (float loop_bw,
+						      float max_freq, float min_freq);
 
-  float d_alpha,d_beta,d_max_freq,d_min_freq,d_phase,d_freq;
-  gr_pll_refout_cc (float alpha, float beta, float max_freq, float min_freq);
+  gr_pll_refout_cc (float loop_bw, float max_freq, float min_freq);
 
   int work (int noutput_items,
 	    gr_vector_const_void_star &input_items,
 	    gr_vector_void_star &output_items);
 private:
   float mod_2pi (float in);
-  float phase_detector(gr_complex sample,float ref_phase);
+  float phase_detector(gr_complex sample, float ref_phase);
 };
 
 #endif
diff --git a/gnuradio-core/src/lib/general/gr_pll_refout_cc.i b/gnuradio-core/src/lib/general/gr_pll_refout_cc.i
index 026a684ed..834ea1e36 100644
--- a/gnuradio-core/src/lib/general/gr_pll_refout_cc.i
+++ b/gnuradio-core/src/lib/general/gr_pll_refout_cc.i
@@ -1,6 +1,6 @@
 /* -*- c++ -*- */
 /*
- * Copyright 2005 Free Software Foundation, Inc.
+ * Copyright 2005,2011 Free Software Foundation, Inc.
  * 
  * This file is part of GNU Radio
  * 
@@ -22,11 +22,11 @@
 
 GR_SWIG_BLOCK_MAGIC(gr,pll_refout_cc)
 
-  gr_pll_refout_cc_sptr gr_make_pll_refout_cc (float alpha, float beta, 
-						 float max_freq, float min_freq);
+gr_pll_refout_cc_sptr gr_make_pll_refout_cc (float loop_bw, 
+					     float max_freq, float min_freq);
 
-class gr_pll_refout_cc : public gr_sync_block
+class gr_pll_refout_cc : public gr_sync_block, public gri_control_loop
 {
  private:
-  gr_pll_refout_cc (float alpha, float beta, float max_freq, float min_freq);
+  gr_pll_refout_cc (float loop_bw, float max_freq, float min_freq);
 };
diff --git a/gnuradio-core/src/lib/general/gri_control_loop.cc b/gnuradio-core/src/lib/general/gri_control_loop.cc
new file mode 100644
index 000000000..d84b47493
--- /dev/null
+++ b/gnuradio-core/src/lib/general/gri_control_loop.cc
@@ -0,0 +1,183 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2011 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.
+ */
+
+#include <gri_control_loop.h>
+#include <gr_math.h>
+#include <stdexcept>
+
+#define M_TWOPI (2.0f*M_PI)
+
+gri_control_loop::gri_control_loop(float loop_bw,
+				   float max_freq, float min_freq)
+  : d_phase(0), d_freq(0), d_max_freq(max_freq), d_min_freq(min_freq)
+{
+  // Set the damping factor for a critically damped system
+  d_damping = sqrtf(2.0f)/2.0f;
+
+  // Set the bandwidth, which will then call update_gains()
+  set_loop_bandwidth(loop_bw);
+}
+
+gri_control_loop::~gri_control_loop()
+{
+}
+
+void
+gri_control_loop::update_gains()
+{
+  float denom = (1.0 + 2.0*d_damping*d_loop_bw + d_loop_bw*d_loop_bw);
+  d_alpha = (4*d_damping*d_loop_bw) / denom;
+  d_beta = (4*d_loop_bw*d_loop_bw) / denom;
+}
+
+void
+gri_control_loop::advance_loop(float error)
+{
+  d_freq = d_freq + d_beta * error;
+  d_phase = d_phase + d_freq + d_alpha * error;
+}
+
+
+void
+gri_control_loop::phase_wrap()
+{
+  while(d_phase>M_TWOPI)
+    d_phase -= M_TWOPI;
+  while(d_phase<-M_TWOPI)
+    d_phase += M_TWOPI;
+}
+
+void
+gri_control_loop::frequency_limit()
+{  
+  if (d_freq > d_max_freq)
+    d_freq = d_min_freq;
+  else if (d_freq < d_min_freq)
+    d_freq = d_max_freq;  
+}
+
+/*******************************************************************
+    SET FUNCTIONS
+*******************************************************************/
+
+void
+gri_control_loop::set_loop_bandwidth(float bw)
+{
+  if(bw < 0) {
+    throw std::out_of_range ("gri_control_loop: invalid bandwidth. Must be >= 0.");
+  }
+  
+  d_loop_bw = bw;
+  update_gains();
+}
+
+void
+gri_control_loop::set_damping_factor(float df) 
+{
+  if(df < 0 || df > 1.0) {
+    throw std::out_of_range ("gri_control_loop: invalid damping factor. Must be in [0,1].");
+  }
+  
+  d_damping = df;
+  update_gains();
+}
+
+void
+gri_control_loop::set_alpha(float alpha)
+{
+  if(alpha < 0 || alpha > 1.0) {
+    throw std::out_of_range ("gri_control_loop: invalid alpha. Must be in [0,1].");
+  }
+  d_alpha = alpha;
+}
+
+void
+gri_control_loop::set_beta(float beta)
+{
+  if(beta < 0 || beta > 1.0) {
+    throw std::out_of_range ("gri_control_loop: invalid beta. Must be in [0,1].");
+  }
+  d_beta = beta;
+}
+
+void
+gri_control_loop::set_frequency(float freq)
+{
+  if(freq > d_max_freq)
+    d_freq = d_min_freq;
+  else if(freq < d_min_freq)
+    d_freq = d_max_freq;
+  else
+    d_freq = freq;
+}
+
+void
+gri_control_loop::set_phase(float phase)
+{
+  d_phase = phase;
+  while(d_phase>M_TWOPI)
+    d_phase -= M_TWOPI;
+  while(d_phase<-M_TWOPI)
+    d_phase += M_TWOPI;
+}
+
+   
+/*******************************************************************
+    GET FUNCTIONS
+*******************************************************************/
+
+
+float
+gri_control_loop::get_loop_bandwidth() const
+{
+  return d_loop_bw;
+}
+
+float
+gri_control_loop::get_damping_factor() const
+{
+  return d_damping;
+}
+
+float
+gri_control_loop::get_alpha() const
+{
+  return d_alpha;
+}
+
+float
+gri_control_loop::get_beta() const
+{
+  return d_beta;
+}
+
+float
+gri_control_loop::get_frequency() const
+{
+  return d_freq;
+}
+
+float
+gri_control_loop::get_phase() const
+{
+  return d_phase;
+}
diff --git a/gnuradio-core/src/lib/general/gri_control_loop.h b/gnuradio-core/src/lib/general/gri_control_loop.h
new file mode 100644
index 000000000..3aeac58f7
--- /dev/null
+++ b/gnuradio-core/src/lib/general/gri_control_loop.h
@@ -0,0 +1,203 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2011 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 GRI_CONTROL_LOOP
+#define GRI_CONTROL_LOOP
+
+#include <gr_core_api.h>
+
+class GR_CORE_API gri_control_loop
+{
+ protected:
+  float d_phase, d_freq;
+  float d_max_freq, d_min_freq;
+  float d_damping, d_loop_bw;
+  float d_alpha, d_beta;
+
+ public:
+  gri_control_loop(float loop_bw, float max_freq, float min_freq);
+  virtual ~gri_control_loop();
+
+  /*! \brief update the system gains from the loop bandwidth and damping factor
+   *
+   *  This function updates the system gains based on the loop
+   *  bandwidth and damping factor of the system.
+   *  These two factors can be set separately through their own
+   *  set functions.
+   */
+  void update_gains();
+
+  /*! \brief update the system gains from the loop bandwidth and damping factor
+   *
+   *  This function updates the system gains based on the loop
+   *  bandwidth and damping factor of the system.
+   *  These two factors can be set separately through their own
+   *  set functions.
+   */
+  void advance_loop(float error);
+
+  /*! \brief Keep the phase between -2pi and 2pi
+   *
+   * This function keeps the phase between -2pi and 2pi. If the phase
+   * is greater than 2pi by d, it wraps around to be -2pi+d; similarly if
+   * it is less than -2pi by d, it wraps around to 2pi-d.
+   *
+   * This function should be called after advance_loop to keep the phase
+   * in a good operating region. It is set as a separate method in case
+   * another way is desired as this is fairly heavy-handed.
+   */
+  void phase_wrap();
+
+  /*! \brief Keep the frequency between d_min_freq and d_max_freq
+   *
+   * This function keeps the frequency between d_min_freq and d_max_freq.
+   * If the frequency is greater than d_max_freq, it is set to d_max_freq.
+   * If the frequency is less than d_min_freq, it is set to d_min_freq.
+   *
+   * This function should be called after advance_loop to keep the frequency
+   * in the specified region. It is set as a separate method in case
+   * another way is desired as this is fairly heavy-handed.
+   */
+  void frequency_limit();
+
+  /*******************************************************************
+    SET FUNCTIONS
+  *******************************************************************/
+
+  /*!
+   * \brief Set the loop bandwidth
+   *
+   * Set the loop filter's bandwidth to \p bw. This should be between 
+   * 2*pi/200 and 2*pi/100  (in rads/samp). It must also be a positive
+   * number.
+   *
+   * When a new damping factor is set, the gains, alpha and beta, of the loop
+   * are recalculated by a call to update_gains().
+   *
+   * \param bw    (float) new bandwidth
+   *
+   */
+  void set_loop_bandwidth(float bw);
+
+  /*!
+   * \brief Set the loop damping factor
+   *
+   * Set the loop filter's damping factor to \p df. The damping factor
+   * should be sqrt(2)/2.0 for critically damped systems.
+   * Set it to anything else only if you know what you are doing. It must
+   * be a number between 0 and 1.
+   *
+   * When a new damping factor is set, the gains, alpha and beta, of the loop
+   * are recalculated by a call to update_gains().
+   *
+   * \param df    (float) new damping factor
+   *
+   */
+  void set_damping_factor(float df);
+
+  /*!
+   * \brief Set the loop gain alpha
+   *
+   * Set's the loop filter's alpha gain parameter.
+   *
+   * This value should really only be set by adjusting the loop bandwidth
+   * and damping factor.
+   *
+   * \param alpha    (float) new alpha gain
+   *
+   */
+  void set_alpha(float alpha);
+
+  /*!
+   * \brief Set the loop gain beta
+   *
+   * Set's the loop filter's beta gain parameter.
+   *
+   * This value should really only be set by adjusting the loop bandwidth
+   * and damping factor.
+   *
+   * \param beta    (float) new beta gain
+   *
+   */
+  void set_beta(float beta);
+
+  /*!
+   * \brief Set the Costas loop's frequency.
+   *
+   * Set's the Costas Loop's frequency. While this is normally updated by the
+   * inner loop of the algorithm, it could be useful to manually initialize,
+   * set, or reset this under certain circumstances.
+   *
+   * \param freq    (float) new frequency
+   *
+   */
+  void set_frequency(float freq);
+
+  /*!
+   * \brief Set the Costas loop's phase.
+   *
+   * Set's the Costas Loop's phase. While this is normally updated by the
+   * inner loop of the algorithm, it could be useful to manually initialize,
+   * set, or reset this under certain circumstances.
+   *
+   * \param phase    (float) new phase
+   *
+   */
+  void set_phase(float phase);
+
+   
+  /*******************************************************************
+    GET FUNCTIONS
+  *******************************************************************/
+
+  /*!
+   * \brief Returns the loop bandwidth
+   */
+  float get_loop_bandwidth() const;
+
+  /*!
+   * \brief Returns the loop damping factor
+   */
+  float get_damping_factor() const;
+
+  /*!
+   * \brief Returns the loop gain alpha
+   */
+  float get_alpha() const;
+
+  /*!
+   * \brief Returns the loop gain beta
+   */
+  float get_beta() const;
+
+  /*!
+   * \brief Get the Costas loop's frequency estimate
+   */
+  float get_frequency() const;
+
+  /*!
+   * \brief Get the Costas loop's phase estimate
+   */
+  float get_phase() const;
+};
+
+#endif /* GRI_CONTROL_LOOP */
diff --git a/gnuradio-core/src/lib/general/gri_control_loop.i b/gnuradio-core/src/lib/general/gri_control_loop.i
new file mode 100644
index 000000000..67f8838cb
--- /dev/null
+++ b/gnuradio-core/src/lib/general/gri_control_loop.i
@@ -0,0 +1,57 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2011 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.
+ */
+
+
+class gri_control_loop
+{
+ public:
+  gri_control_loop(float loop_bw, float max_freq, float min_freq);
+  virtual ~gri_control_loop();
+
+  void update_gains();
+  void advance_loop(float error);
+  void phase_wrap();
+  void frequency_limit();
+
+  /*******************************************************************
+    SET FUNCTIONS
+  *******************************************************************/
+
+  void set_loop_bandwidth(float bw);
+  void set_damping_factor(float df);
+  void set_alpha(float alpha);
+  void set_beta(float beta);
+  void set_frequency(float freq);
+  void set_phase(float phase);
+
+   
+  /*******************************************************************
+    GET FUNCTIONS
+  *******************************************************************/
+
+  float get_loop_bandwidth() const;
+  float get_damping_factor() const;
+  float get_alpha() const;
+  float get_beta() const;
+  float get_frequency() const;
+  float get_phase() const;
+};