diff options
Diffstat (limited to 'gr-atsc/include/atsc/slicer_agc_impl.h')
-rw-r--r-- | gr-atsc/include/atsc/slicer_agc_impl.h | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/gr-atsc/include/atsc/slicer_agc_impl.h b/gr-atsc/include/atsc/slicer_agc_impl.h new file mode 100644 index 0000000000..91694c09db --- /dev/null +++ b/gr-atsc/include/atsc/slicer_agc_impl.h @@ -0,0 +1,69 @@ +/* -*- 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 <atsc/api.h> +#include <math.h> +#include <filter/single_pole_iir.h> + +/*! + * \brief Automatic Gain Control class for atsc slicer + * + * Given perfect data, output values will be +/- {7, 5, 3, 1} + */ + +class ATSC_API 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_ */ |