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/* -*- c++ -*- */
/* Copyright 2012 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio 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.
*
* GNU Radio 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 GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef INCLUDED_DIGITAL_OFDM_EQUALIZER_STATIC_H
#define INCLUDED_DIGITAL_OFDM_EQUALIZER_STATIC_H
#include <digital/api.h>
#include <digital/constellation.h>
#include <digital/ofdm_equalizer_base.h>
namespace gr {
namespace digital {
/* \brief Very simple static equalizer for OFDM.
* \ingroup ofdm_blk
* \ingroup eq_blk
*
* This is an extremely simple equalizer. It will only work for high-SNR, very, very
* slowly changing channels.
* It simply divides the signal with the currently known channel state. Whenever
* a pilot symbol comes around, it updates the channel state on that particular
* carrier by dividing the received symbol with the known pilot symbol.
*/
class DIGITAL_API ofdm_equalizer_static : public ofdm_equalizer_1d_pilots
{
public:
typedef boost::shared_ptr<ofdm_equalizer_static> sptr;
ofdm_equalizer_static(
int fft_len,
const std::vector<std::vector<int> > &occupied_carriers = std::vector<std::vector<int> >(),
const std::vector<std::vector<int> > &pilot_carriers = std::vector<std::vector<int> >(),
const std::vector<std::vector<gr_complex> > &pilot_symbols = std::vector<std::vector<gr_complex> >(),
int symbols_skipped = 0,
bool input_is_shifted = true
);
~ofdm_equalizer_static();
/*! \brief Divide the input signal with the current channel state.
*
* Does the following (and nothing else):
* - Divide every OFDM symbol with the current channel state
* - If a pilot symbol is found, re-set the channel state by dividing the received
* symbol with the known pilot symbol
*/
void equalize(gr_complex *frame,
int n_sym,
const std::vector<gr_complex> &initial_taps = std::vector<gr_complex>(),
const std::vector<gr_tag_t> &tags = std::vector<gr_tag_t>());
/*
* \param fft_len FFT length
* \param occupied_carriers List of occupied carriers, see ofdm_carrier_allocator
* for a description.
* \param pilot_carriers Position of pilot symbols, see ofdm_carrier_allocator
* for a description.
* \param pilot_symbols Value of pilot symbols, see ofdm_carrier_allocator
* for a description.
* \param symbols_skipped Starting position within occupied_carriers and pilot_carriers.
* If the first symbol of the frame was removed (e.g. to decode the
* header), set this make sure the pilot symbols are correctly
* identified.
* \param input_is_shifted Set this to false if the input signal is not shifted, i.e.
* the first input items is on the DC carrier.
* Note that a lot of the OFDM receiver blocks operate on shifted
* signals!
*/
static sptr make(
int fft_len,
const std::vector<std::vector<int> > &occupied_carriers = std::vector<std::vector<int> >(),
const std::vector<std::vector<int> > &pilot_carriers = std::vector<std::vector<int> >(),
const std::vector<std::vector<gr_complex> > &pilot_symbols = std::vector<std::vector<gr_complex> >(),
int symbols_skipped = 0,
bool input_is_shifted = true
);
};
} /* namespace digital */
} /* namespace gr */
#endif /* INCLUDED_DIGITAL_OFDM_EQUALIZER_STATIC_H */
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