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/* -*- c++ -*- */
/*
* Copyright 2006,2007,2011,2012 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_FRAME_ACQUISITION_IMPL_H
#define INCLUDED_DIGITAL_OFDM_FRAME_ACQUISITION_IMPL_H
#include <gnuradio/digital/ofdm_frame_acquisition.h>
namespace gr {
namespace digital {
class ofdm_frame_acquisition_impl : public ofdm_frame_acquisition
{
private:
unsigned char slicer(gr_complex x);
void correlate(const gr_complex *symbol, int zeros_on_left);
void calculate_equalizer(const gr_complex *symbol, int zeros_on_left);
gr_complex coarse_freq_comp(int freq_delta, int count);
unsigned int d_occupied_carriers; // !< \brief number of subcarriers with data
unsigned int d_fft_length; // !< \brief length of FFT vector
unsigned int d_cplen; // !< \brief length of cyclic prefix in samples
unsigned int d_freq_shift_len; // !< \brief number of surrounding bins to look at for correlation
std::vector<gr_complex> d_known_symbol; // !< \brief known symbols at start of frame
std::vector<float> d_known_phase_diff; // !< \brief factor used in correlation from known symbol
std::vector<float> d_symbol_phase_diff; // !< \brief factor used in correlation from received symbol
std::vector<gr_complex> d_hestimate; // !< channel estimate
int d_coarse_freq; // !< \brief search distance in number of bins
unsigned int d_phase_count; // !< \brief accumulator for coarse freq correction
float d_snr_est; // !< an estimation of the signal to noise ratio
gr_complex *d_phase_lut; // !< look-up table for coarse frequency compensation
void forecast(int noutput_items, gr_vector_int &ninput_items_required);
public:
ofdm_frame_acquisition_impl(unsigned int occupied_carriers, unsigned int fft_length,
unsigned int cplen,
const std::vector<gr_complex> &known_symbol,
unsigned int max_fft_shift_len=4);
~ofdm_frame_acquisition_impl();
/*!
* \brief Return an estimate of the SNR of the channel
*/
float snr() { return d_snr_est; }
int general_work(int noutput_items,
gr_vector_int &ninput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items);
};
} /* namespace digital */
} /* namespace gr */
#endif /* INCLUDED_DIGITAL_OFDM_FRAME_ACQUISITION_IMPL_H */
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