GNU Radio 3.6.4 C++ API
digital_costas_loop_cc.h
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1 /* -*- c++ -*- */
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22 
23 
24 #ifndef INCLUDED_DIGITAL_COSTAS_LOOP_CC_H
25 #define INCLUDED_DIGITAL_COSTAS_LOOP_CC_H
26 
27 #include <gr_sync_block.h>
28 #include <gri_control_loop.h>
29 #include <stdexcept>
30 #include <fstream>
31 
32 
33 /*!
34  * \brief A Costas loop carrier recovery module.
35  * \ingroup sync_blk
36  * \ingroup digital
37  *
38  * The Costas loop locks to the center frequency of a signal and
39  * downconverts it to baseband. The second (order=2) order loop is
40  * used for BPSK where the real part of the output signal is the
41  * baseband BPSK signal and the imaginary part is the error
42  * signal. When order=4, it can be used for quadrature modulations
43  * where both I and Q (real and imaginary) are outputted.
44  *
45  * More details can be found online:
46  *
47  * J. Feigin, "Practical Costas loop design: Designing a simple and
48  * inexpensive BPSK Costas loop carrier recovery circuit," RF signal
49  * processing, pp. 20-36, 2002.
50  *
51  * http://rfdesign.com/images/archive/0102Feigin20.pdf
52  *
53  * \param loop_bw internal 2nd order loop bandwidth (~ 2pi/100)
54  * \param order the loop order, either 2, 4, or 8
55  */
56 
57 #include <digital_api.h>
58 
61 
62 
64 digital_make_costas_loop_cc (float loop_bw, int order
65  ) throw (std::invalid_argument);
66 
67 
68 /*!
69  * \brief Carrier tracking PLL for QPSK
70  * \ingroup sync_blk
71  * input: complex; output: complex
72  * <br>The Costas loop can have two output streams:
73  * stream 1 is the baseband I and Q;
74  * stream 2 is the normalized frequency of the loop
75  *
76  * \p order must be 2, 4, or 8.
77  */
79 {
81  digital_make_costas_loop_cc (float loop_bw, int order
82  ) throw (std::invalid_argument);
83 
84  int d_order;
85 
86  digital_costas_loop_cc (float loop_bw, int order
87  ) throw (std::invalid_argument);
88 
89  /*! \brief the phase detector circuit for 8th-order PSK loops
90  * \param sample complex sample
91  * \return the phase error
92  */
93  float phase_detector_8(gr_complex sample) const; // for 8PSK
94 
95  /*! \brief the phase detector circuit for fourth-order loops
96  * \param sample complex sample
97  * \return the phase error
98  */
99  float phase_detector_4(gr_complex sample) const; // for QPSK
100 
101  /*! \brief the phase detector circuit for second-order loops
102  * \param sample a complex sample
103  * \return the phase error
104  */
105  float phase_detector_2(gr_complex sample) const; // for BPSK
106 
107 
108  float (digital_costas_loop_cc::*d_phase_detector)(gr_complex sample) const;
109 
110 public:
111 
112  int work (int noutput_items,
113  gr_vector_const_void_star &input_items,
114  gr_vector_void_star &output_items);
115 };
116 
117 #endif