GNU Radio Manual and C++ API Reference 3.7.14.0
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ccsds_encoder.h
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1/* -*- c++ -*- */
2/*
3 * Copyright 2014 Free Software Foundation, Inc.
4 *
5 * This file is part of GNU Radio
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22
23#ifndef INCLUDED_FEC_CCSDS_ENCODER_H
24#define INCLUDED_FEC_CCSDS_ENCODER_H
25
26#include <gnuradio/fec/api.h>
29#include <map>
30#include <string>
31
32namespace gr {
33namespace fec {
34namespace code {
35
36/*!
37 * \brief CCSDS Encoding class for convolutional encoding with
38 * rate 1/2, K=7, and polynomials [109, 79].
39 * \ingroup error_coding_blk
40 *
41 * \details
42 *
43 * Uses Phil Karn's (KA9Q) implementation of the CCSDS encoder
44 * for rate 1/2, K=7, and CC polynomial [109, 79]. These are
45 * non-adjustable in this encoder. For an adjustable CC encoder
46 * where we can set the rate, constraint length, and polynomial,
47 * see gr::fec::code::cc_encoder.
48 *
49 * The encoder is set up with a number of bits per frame in the
50 * constructor. When not being used in a tagged stream mode,
51 * this encoder will only process frames of the length provided
52 * here. If used in a tagged stream block, this setting becomes
53 * the maximum allowable frame size that the block may process.
54 *
55 * The \p mode is a cc_mode_t that specifies how the convolutional
56 * encoder will behave and under what conditions.
57 *
58 * \li 'CC_STREAMING': mode expects an uninterrupted flow of
59 * samples into the encoder, and the output stream is
60 * continually encoded.
61 *
62 * \li 'CC_TERMINATED': is a mode designed for packet-based
63 * systems. This mode adds rate*(k-1) bits to the output as a
64 * way to help flush the decoder.
65 *
66 * \li 'CC_TAILBITING': is another packet-based method. Instead of
67 * adding bits onto the end of the packet, this mode will
68 * continue the code between the payloads of packets by
69 * pre-initializing the state of the new packet based on the
70 * state of the last packet for (k-1) bits.
71 *
72 * \li 'CC_TRUNCATED': a truncated code always resets the registers
73 * to the \p start_state between frames.
74 *
75 * A common convolutional encoder uses K=7, Rate=1/2,
76 * Polynomials=[109, 79]. This is the Voyager code from NASA:
77 * \li 109: b(1101101) --> 1 + x + x^3 + x^4 + x^6
78 * \li 79: b(1001111) --> 1 + x^3 + x^4 + x^5 + x^6
79 */
81{
82public:
83 /*!
84 * Build the CCSDS (rate=1/2, K=7, polys=[109,79]
85 * convolutional code FECAPI object.
86 *
87 * \param frame_size Number of bits per frame. If using in the
88 * tagged stream style, this is the maximum allowable
89 * number of bits per frame.
90 * \param start_state Initialization state of the shift register.
91 * \param mode cc_mode_t mode of the encoding.
92 */
94 make(int frame_size, int start_state = 0, cc_mode_t mode = CC_STREAMING);
95
96 /*!
97 * Sets the uncoded frame size to \p frame_size. If \p
98 * frame_size is greater than the value given to the
99 * constructor, the frame size will be capped by that initial
100 * value and this function will return false. Otherwise, it
101 * returns true.
102 */
103 virtual bool set_frame_size(unsigned int frame_size) = 0;
104
105 /*!
106 * Returns the coding rate of this encoder.
107 */
108 virtual double rate() = 0;
109};
110
111} /* namespace code */
112} /* namespace fec */
113} /* namespace gr */
114
115#endif /* INCLUDED_FEC_CCSDS_ENCODER_H */
enum _cc_mode_t cc_mode_t
@ CC_STREAMING
Definition: cc_common.h:27
CCSDS Encoding class for convolutional encoding with rate 1/2, K=7, and polynomials [109,...
Definition: ccsds_encoder.h:81
virtual double rate()=0
static generic_encoder::sptr make(int frame_size, int start_state=0, cc_mode_t mode=CC_STREAMING)
virtual bool set_frame_size(unsigned int frame_size)=0
Definition: generic_encoder.h:35
boost::shared_ptr< generic_encoder > sptr
Definition: generic_encoder.h:49
#define FEC_API
Definition: gr-fec/include/gnuradio/fec/api.h:30
Include this header to use the message passing features.
Definition: basic_block.h:45