GNU Radio Manual and C++ API Reference  3.7.13.4
The Free & Open Software Radio Ecosystem
plateau_detector_fb.h
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22 
23 
24 #ifndef INCLUDED_BLOCKS_PLATEAU_DETECTOR_FB_H
25 #define INCLUDED_BLOCKS_PLATEAU_DETECTOR_FB_H
26 
27 #include <gnuradio/blocks/api.h>
28 #include <gnuradio/sync_block.h>
29 
30 namespace gr {
31  namespace blocks {
32 
33  /*!
34  * \brief Detects a plateau and marks the middle.
35  * \ingroup peak_detectors_blk
36  *
37  * \details
38  * Detect a plateau of a-priori known height. Input is a stream of floats,
39  * the output is a stream of bytes. Whenever a plateau is detected, the
40  * middle of that plateau is marked with a '1' on the output stream (all
41  * other samples are left at zero).
42  *
43  * You can use this in a Schmidl & Cox synchronisation algorithm to interpret
44  * the output of the normalized correlator. Just pass the length of the cyclic
45  * prefix (in samples) as the max_len parameter).
46  *
47  * Unlike the peak detectors, you must the now the absolute height of the plateau.
48  * Whenever the amplitude exceeds the given threshold, it starts assuming the
49  * presence of a plateau.
50  *
51  * An implicit hysteresis is provided by the fact that after detecting one plateau,
52  * it waits at least max_len samples before the next plateau can be detected.
53  */
54  class BLOCKS_API plateau_detector_fb : virtual public block
55  {
56  public:
57  typedef boost::shared_ptr<plateau_detector_fb> sptr;
58 
59  /*!
60  * \param max_len Maximum length of the plateau
61  * \param threshold Anything above this value is considered a plateau
62  */
63  static sptr make(int max_len, float threshold=0.9);
64 
65  virtual void set_threshold(float threshold) = 0;
66  virtual float threshold() const = 0;
67  };
68 
69  } // namespace blocks
70 } // namespace gr
71 
72 #endif /* INCLUDED_BLOCKS_PLATEAU_DETECTOR_FB_H */
73 
Include this header to use the message passing features.
Definition: logger.h:695
boost::shared_ptr< plateau_detector_fb > sptr
Definition: plateau_detector_fb.h:57
#define BLOCKS_API
Definition: gr-blocks/include/gnuradio/blocks/api.h:30
Detects a plateau and marks the middle.
Definition: plateau_detector_fb.h:54
The abstract base class for all &#39;terminal&#39; processing blocks.A signal processing flow is constructed ...
Definition: block.h:65