GNU Radio 3.5.3.1 C++ API
digital_mpsk_snr_est_cc.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2011 Free Software Foundation, Inc.
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5  * This file is part of GNU Radio
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22 #ifndef INCLUDED_DIGITAL_MPSK_SNR_EST_CC_H
23 #define INCLUDED_DIGITAL_MPSK_SNR_EST_CC_H
24 
25 #include <digital_api.h>
26 #include <gr_sync_block.h>
28 
31 
34  int tag_nsamples=10000,
35  double alpha=0.001);
36 
37 //! \brief A block for computing SNR of a signal.
38 /*! \ingroup snr_blk
39  *
40  * This block can be used to monitor and retrieve estimations of the
41  * signal SNR. It is designed to work in a flowgraph and passes all
42  * incoming data along to its output.
43  *
44  * The block is designed for use with M-PSK signals especially. The
45  * type of estimator is specified as the \p type parameter in the
46  * constructor. The estimators tend to trade off performance for
47  * accuracy, although experimentation should be done to figure out
48  * the right approach for a given implementation. Further, the
49  * current set of estimators are designed and proven theoretically
50  * under AWGN conditions; some amount of error should be assumed
51  * and/or estimated for real channel conditions.
52  */
54 {
55  private:
56  snr_est_type_t d_type;
57  int d_nsamples, d_count;
58  double d_alpha;
59  digital_impl_mpsk_snr_est *d_snr_est;
60 
61  //d_key is the tag name, 'snr', d_me is the block name + unique ID
62  pmt::pmt_t d_key, d_me;
63 
64  /*! Factory function returning shared pointer of this class
65  *
66  * Parameters:
67  *
68  * \param type: the type of estimator to use \ref ref_snr_est_types
69  * "snr_est_type_t" for details about the available types.
70  * \param tag_nsamples: after this many samples, a tag containing
71  * the SNR (key='snr') will be sent
72  * \param alpha: the update rate of internal running average
73  * calculations.
74  */
77  int tag_nsamples,
78  double alpha);
79 
80  // Private constructor
82  int tag_nsamples,
83  double alpha);
84 
85 public:
86 
88 
89  int work (int noutput_items,
90  gr_vector_const_void_star &input_items,
91  gr_vector_void_star &output_items);
92 
93  //! Return the estimated signal-to-noise ratio in decibels
94  double snr();
95 
96  //! Return the type of estimator in use
97  snr_est_type_t type() const;
98 
99  //! Return how many samples between SNR tags
100  int tag_nsample() const;
101 
102  //! Get the running-average coefficient
103  double alpha() const;
104 
105  //! Set type of estimator to use
106  void set_type(snr_est_type_t t);
107 
108  //! Set the number of samples between SNR tags
109  void set_tag_nsample(int n);
110 
111  //! Set the running-average coefficient
112  void set_alpha(double alpha);
113 };
114 
115 #endif /* INCLUDED_DIGITAL_MPSK_SNR_EST_CC_H */