X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=gr-atsc%2Fsrc%2Flib%2Fatsci_slicer_agc.h;fp=gr-atsc%2Fsrc%2Flib%2Fatsci_slicer_agc.h;h=2e7d3be7a77e2acd1b9ed3c7877e113ec6b48b0f;hb=8a9ddbb0675f9bfcc6e03b457fba6c79474a3693;hp=0000000000000000000000000000000000000000;hpb=82d471b9b4a8b389b5da44b19c69c36420828382;p=debian%2Fgnuradio

diff --git a/gr-atsc/src/lib/atsci_slicer_agc.h b/gr-atsc/src/lib/atsci_slicer_agc.h
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+/* -*- c++ -*- */
+/*
+ * Copyright 2002 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 _ATSC_SLICER_AGC_H_
+#define _ATSC_SLICER_AGC_H_
+
+#include <math.h>
+#include <gr_single_pole_iir.h>
+
+/*!
+ * \brief Automatic Gain Control class for atsc slicer
+ *
+ * Given perfect data, output values will be +/- {7, 5, 3, 1}
+ */
+
+class atsci_slicer_agc {
+
+ public:
+  atsci_slicer_agc () : _gain(1), dc(0.0025) {};
+
+  
+  float gain () { return _gain; }
+
+#if 1
+  float scale (float input){
+    float t = input * _gain;
+    float output = t - REFERENCE;
+    float error = REFERENCE - dc.filter (t);
+    _gain += error * RATE;
+    return output;
+  }
+#else
+  float scale(float input){
+    float avg = dc.filter(input);
+    if(fabs(avg)<.1)avg=.1;
+    _gain += _gain*.99 + .01* REFERENCE/avg;
+    return input*_gain - REFERENCE;
+  }
+#endif
+
+ protected:
+  
+  static const float			REFERENCE = 1.25;	// pilot reference value
+  static const float 			RATE = 1.0e-5;		// adjustment rate
+  float					_gain;			// current gain
+  gr_single_pole_iir<float,float,float>	dc;
+};
+
+#endif /* _ATSC_SLICER_AGC_H_ */