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diff --git a/gnuradio-core/src/lib/general/gri_agc.h b/gnuradio-core/src/lib/general/gri_agc.h
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+++ b/gnuradio-core/src/lib/general/gri_agc.h
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+/* -*- c++ -*- */
+/*
+ * Copyright 2002,2006 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 2, 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef _GRI_AGC_H_
+#define _GRI_AGC_H_
+
+#include <math.h>
+
+/*!
+ * \brief high performance Automatic Gain Control class
+ *
+ * Power is approximated by absolute value
+ */
+
+class gri_agc {
+
+ public:
+  gri_agc (float rate = 1e-4, float reference = 1.0, float gain = 1.0, float max_gain = 0.0)
+    : _rate(rate), _reference(reference), _gain(gain), _max_gain(max_gain) {};
+
+  float rate () const      { return _rate; }
+  float reference () const { return _reference; }
+  float gain () const 	   { return _gain;  }
+  float max_gain () const  { return _max_gain; }
+  
+  void set_rate (float rate) { _rate = rate; }
+  void set_reference (float reference) { _reference = reference; }
+  void set_gain (float gain) { _gain = gain; }
+  void set_max_gain (float max_gain) { _max_gain = max_gain; }
+  
+  float scale (float input){
+    float output = input * _gain;
+    _gain += (_reference - fabsf (output)) * _rate;
+    if (_max_gain > 0.0 && _gain > _max_gain)
+      _gain = _max_gain;
+    return output;
+  }
+
+  void scaleN (float output[], const float input[], unsigned n){
+    for (unsigned i = 0; i < n; i++)
+      output[i] = scale (input[i]);
+  }
+  
+ protected:
+  float _rate;			// adjustment rate
+  float	_reference;		// reference value
+  float	_gain;			// current gain
+  float _max_gain;		// maximum gain
+};
+
+#endif /* _GRI_AGC_H_ */