lib/receiver/viterbi_detector.h

/* -*- c++ -*- */
/*
 * @file
 * @author (C) 2009 Piotr Krysik <ptrkrysik@gmail.com>
 * @section LICENSE
 *
 * Gr-gsm is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3, or (at your option)
 * any later version.
 *
 * Gr-gsm is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with gr-gsm; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

/*
 * viterbi_detector:
 *           This part does the detection of received sequnece.
 *           Employed algorithm is viterbi Maximum Likehood Sequence Estimation.
 *           At this moment it gives hard decisions on the output, but
 *           it was designed with soft decisions in mind.
 *
 * SYNTAX:   void viterbi_detector(
 *                                  const gr_complex * input, 
 *                                  unsigned int samples_num, 
 *                                  gr_complex * rhh, 
 *                                  unsigned int start_state, 
 *                                  const unsigned int * stop_states, 
 *                                  unsigned int stops_num, 
 *                                  float * output)
 *
 * INPUT:    input:       Complex received signal afted matched filtering.
 *           samples_num: Number of samples in the input table.
 *           rhh:         The autocorrelation of the estimated channel 
 *                        impulse response.
 *           start_state: Number of the start point. In GSM each burst 
 *                        starts with sequence of three bits (0,0,0) which 
 *                        indicates start point of the algorithm.
 *           stop_states: Table with numbers of possible stop states.
 *           stops_num:   Number of possible stop states
 *                     
 *
 * OUTPUT:   output:      Differentially decoded hard output of the algorithm: 
 *                        -1 for logical "0" and 1 for logical "1"
 *
 * SUB_FUNC: none
 *
 * TEST(S):  Tested with real world normal burst.
 */

#ifndef INCLUDED_VITERBI_DETECTOR_H
#define INCLUDED_VITERBI_DETECTOR_H

void viterbi_detector(const gr_complex * input, unsigned int samples_num, gr_complex * rhh, unsigned int start_state, const unsigned int * stop_states, unsigned int stops_num, float * output);

#endif /* INCLUDED_VITERBI_DETECTOR_H */