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/* -*- c++ -*- */
/*
* Copyright 2012-2013 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#ifndef INCLUDED_BLOCKS_PLATEAU_DETECTOR_FB_H
#define INCLUDED_BLOCKS_PLATEAU_DETECTOR_FB_H
#include <gnuradio/blocks/api.h>
#include <gnuradio/sync_block.h>
namespace gr {
namespace blocks {
/*!
* \brief Detects a plateau and marks the middle.
* \ingroup peak_detectors_blk
*
* \details
* 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.
*/
class BLOCKS_API plateau_detector_fb : virtual public 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);
virtual void set_threshold(float threshold) = 0;
virtual float threshold() const = 0;
};
} // namespace blocks
} // namespace gr
#endif /* INCLUDED_BLOCKS_PLATEAU_DETECTOR_FB_H */
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