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Diffstat (limited to 'gr-digital/include/digital/ofdm_equalizer_static.h')
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1 files changed, 100 insertions, 0 deletions
diff --git a/gr-digital/include/digital/ofdm_equalizer_static.h b/gr-digital/include/digital/ofdm_equalizer_static.h new file mode 100644 index 0000000000..67586be6fb --- /dev/null +++ b/gr-digital/include/digital/ofdm_equalizer_static.h @@ -0,0 +1,100 @@ +/* -*- 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 */ + |