GNU Radio Manual and C++ API Reference  3.7.9.2
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dc_blocker_ff.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2011,2012 Free Software Foundation, Inc.
4  *
5  * This file is part of GNU Radio
6  *
7  * GNU Radio is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
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22 
23 #ifndef INCLUDED_FILTER_DC_BLOCKER_FF_H
24 #define INCLUDED_FILTER_DC_BLOCKER_FF_H
25 
26 #include <gnuradio/filter/api.h>
27 #include <gnuradio/sync_block.h>
28 
29 namespace gr {
30  namespace filter {
31 
32  /*!
33  * \brief a computationally efficient controllable DC blocker
34  * \ingroup filter_blk
35  *
36  * \details
37  * This block implements a computationally efficient DC blocker
38  * that produces a tighter notch filter around DC for a smaller
39  * group delay than an equivalent FIR filter or using a single
40  * pole IIR filter (though the IIR filter is computationally
41  * cheaper).
42  *
43  * The block defaults to using a delay line of length 32 and the
44  * long form of the filter. Optionally, the delay line length can
45  * be changed to alter the width of the DC notch (longer lines
46  * will decrease the width).
47  *
48  * The long form of the filter produces a nearly flat response
49  * outside of the notch but at the cost of a group delay of 2D-2.
50  *
51  * The short form of the filter does not have as flat a response
52  * in the passband but has a group delay of only D-1 and is
53  * cheaper to compute.
54  *
55  * The theory behind this block can be found in the paper:
56  *
57  * <B><EM>R. Yates, "DC Blocker Algorithms," IEEE Signal Processing Magazine,
58  * Mar. 2008, pp 132-134.</EM></B>
59  */
60  class FILTER_API dc_blocker_ff : virtual public sync_block
61  {
62  public:
63 
64  // gr::filter::dc_blocker_ff::sptr
65  typedef boost::shared_ptr<dc_blocker_ff> sptr;
66 
67  /*!
68  * Make a DC blocker block.
69  *
70  * \param D (int) the length of the delay line
71  * \param long_form (bool) whether to use long (true, default) or short form
72  */
73  static sptr make(int D, bool long_form=true);
74 
75  virtual int group_delay() = 0;
76  };
77 
78  } /* namespace filter */
79 } /* namespace gr */
80 
81 #endif /* INCLUDED_FILTER_DC_BLOCKER_FF_H */
boost::shared_ptr< dc_blocker_ff > sptr
Definition: dc_blocker_ff.h:65
a computationally efficient controllable DC blocker
Definition: dc_blocker_ff.h:60
Include this header to use the message passing features.
Definition: logger.h:131
synchronous 1:1 input to output with historyOverride work to provide the signal processing implementa...
Definition: sync_block.h:37
#define FILTER_API
Definition: gr-filter/include/gnuradio/filter/api.h:30