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ccsds_encoder.h
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/* -*- c++ -*- */
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/*
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* Copyright 2014 Free Software Foundation, Inc.
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*
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* This file is part of GNU Radio
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*
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* GNU Radio is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3, or (at your option)
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* any later version.
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*
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* GNU Radio is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU Radio; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef INCLUDED_FEC_CCSDS_ENCODER_H
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#define INCLUDED_FEC_CCSDS_ENCODER_H
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#include <
gnuradio/fec/api.h
>
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#include <
gnuradio/fec/encoder.h
>
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#include <
gnuradio/fec/cc_common.h
>
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#include <map>
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#include <string>
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namespace
gr {
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namespace
fec {
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namespace
code {
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/*!
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* \brief CCSDS Encoding class for convolutional encoding with
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* rate 1/2, K=7, and polynomials [109, 79].
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* \ingroup error_coding_blk
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*
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* \details
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*
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* Uses Phil Karn's (KA9Q) implementation of the CCSDS encoder
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* for rate 1/2, K=7, and CC polynomial [109, 79]. These are
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* non-adjustable in this encoder. For an adjustable CC encoder
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* where we can set the rate, constraint length, and polynomial,
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* see gr::fec::code::cc_encoder.
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*
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* The encoder is set up wtih a number of bits per frame in the
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* constructor. When not being used in a tagged stream mode,
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* this encoder will only process frames of the length provided
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* here. If used in a tagged stream block, this setting becomes
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* the maximum allowable frame size that the block may process.
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*
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* The \p mode is a cc_mode_t that specifies how the convolutional
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* encoder will behave and under what conditions.
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*
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* \li 'CC_STREAMING': mode expects an uninterrupted flow of
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* samples into the encoder, and the output stream is
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* continually encoded.
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*
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* \li 'CC_TERMINATED': is a mode designed for packet-based
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* systems. This mode adds rate*(k-1) bits to the output as a
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* way to help flush the decoder.
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*
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* \li 'CC_TAILBITING': is another packet-based method. Instead of
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* adding bits onto the end of the packet, this mode will
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* continue the code between the payloads of packets by
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* pre-initializing the state of the new packet based on the
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* state of the last packet for (k-1) bits.
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*
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* \li 'CC_TRUNCATED': a truncated code always resets the registers
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* to the \p start_state between frames.
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*
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* A common convolutional encoder uses K=7, Rate=1/2,
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* Polynomials=[109, 79]. This is the Voyager code from NASA:
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* \li 109: b(1101101) --> 1 + x + x^3 + x^4 + x^6
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* \li 79: b(1001111) --> 1 + x^3 + x^4 + x^5 + x^6
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*/
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class
FEC_API
ccsds_encoder
:
virtual
public
generic_encoder
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{
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public
:
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/*!
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* Build the CCSDS (rate=1/2, K=7, polys=[109,79]
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* convolutional code FECAPI object.
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*
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* \param frame_size Number of bits per frame. If using in the
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* tagged stream style, this is the maximum allowable
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* number of bits per frame.
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* \param start_state Initialization state of the shift register.
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* \param mode cc_mode_t mode of the encoding.
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*/
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static
generic_encoder::sptr
make
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(
int
frame_size,
int
start_state = 0,
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cc_mode_t
mode=
CC_STREAMING
);
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/*!
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* Sets the uncoded frame size to \p frame_size. If \p
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* frame_size is greater than the value given to the
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* constructor, the frame size will be capped by that initial
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* value and this function will return false. Otherwise, it
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* returns true.
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*/
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virtual
bool
set_frame_size(
unsigned
int
frame_size) = 0;
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/*!
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* Returns the coding rate of this encoder.
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*/
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virtual
double
rate() = 0;
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};
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}
/* namespace code */
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}
/* namespace fec */
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}
/* namespace gr */
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#endif
/* INCLUDED_FEC_CCSDS_ENCODER_H */
gr-fec
include
gnuradio
fec
ccsds_encoder.h
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