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/* -*- c++ -*- */
/*
* Copyright 2012-2013 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_BLOCKS_PLATEAU_DETECTOR_FB_H
#define INCLUDED_BLOCKS_PLATEAU_DETECTOR_FB_H
#include <blocks/api.h>
#include <gr_sync_block.h>
namespace gr {
namespace blocks {
/*!
* \brief Detects a plateau and marks the middle.
*
* Detect a plateau of a-priori known height. Input is a stream of floats,
* the output is a stream of bytes. Whenever a plateau is detected, the
* middle of that plateau is marked with a '1' on the output stream (all
* other samples are left at zero).
*
* You can use this in a Schmidl & Cox synchronisation algorithm to interpret
* the output of the normalized correlator. Just pass the length of the cyclic
* prefix (in samples) as the max_len parameter).
*
* Unlike the peak detectors, you must the now the absolute height of the plateau.
* Whenever the amplitude exceeds the given threshold, it starts assuming the
* presence of a plateau.
*
* An implicit hysteresis is provided by the fact that after detecting one plateau,
* it waits at least max_len samples before the next plateau can be detected.
*
* \ingroup level_blk
*
*/
class BLOCKS_API plateau_detector_fb : virtual public gr_sync_block
{
public:
typedef boost::shared_ptr<plateau_detector_fb> sptr;
/*!
* \param max_len Maximum length of the plateau
* \param threshold Anything above this value is considered a plateau
*/
static sptr make(int max_len, float threshold=0.9);
};
} // namespace blocks
} // namespace gr
#endif /* INCLUDED_BLOCKS_PLATEAU_DETECTOR_FB_H */
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