Bastian Bloessl
267 lines
7.8 KiB
C++
267 lines
7.8 KiB
C++
/*
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* Copyright (C) 2013 Bastian Bloessl <bloessl@ccs-labs.org>
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*
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* This program 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 of the License, or
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* (at your option) any later version.
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*
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* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <ieee802-11/ofdm_sync_long.h>
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#include "utils.h"
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#include <gnuradio/io_signature.h>
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#include <gnuradio/filter/fir_filter.h>
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#include <gnuradio/fft/fft.h>
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#include <list>
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#include <tuple>
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using namespace gr::ieee802_11;
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using namespace std;
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class ofdm_sync_long_impl : public ofdm_sync_long {
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public:
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ofdm_sync_long_impl(unsigned int sync_length, bool log, bool debug) : block("ofdm_sync_long",
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gr::io_signature::make2(2, 2, sizeof(gr_complex), sizeof(gr_complex)),
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gr::io_signature::make(1, 1, sizeof(gr_complex))),
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d_log(log),
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d_debug(debug),
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d_offset(0),
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d_freq_est(0),
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d_state(SYNC),
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SYNC_LENGTH(sync_length) {
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set_tag_propagation_policy(block::TPP_DONT);
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d_fir = new gr::filter::kernel::fir_filter_ccc(1, LONG);
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d_correlation = gr::fft::malloc_complex(8192);
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d_freq_est_buf = static_cast<gr_complex*>(std::malloc(sync_length * sizeof(gr_complex)));
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}
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~ofdm_sync_long_impl(){
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delete d_fir;
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gr::fft::free(d_correlation);
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free(d_freq_est_buf);
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}
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int general_work (int noutput, gr_vector_int& ninput_items,
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gr_vector_const_void_star& input_items,
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gr_vector_void_star& output_items) {
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const gr_complex *in = (const gr_complex*)input_items[0];
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const gr_complex *in_delayed = (const gr_complex*)input_items[1];
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gr_complex *out = (gr_complex*)output_items[0];
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dout << "LONG ninput[0] " << ninput_items[0] << " ninput[1] " <<
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ninput_items[1] << " noutput " << noutput <<
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" state " << d_state << std::endl;
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int ninput = std::min(ninput_items[0], ninput_items[1]);
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const unsigned int nread = nitems_read(0);
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get_tags_in_range(d_tags, 0, nread, nread + ninput);
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if (d_tags.size()) {
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std::sort(d_tags.begin(), d_tags.end(), gr::tag_t::offset_compare);
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const gr::tag_t &tag = d_tags.front();
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const uint64_t offset = tag.offset;
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if(offset > nread) {
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ninput = offset - nread;
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} else {
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if(d_state == COPY) {
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d_state = RESET;
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}
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}
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}
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int i = 0;
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int o = 0;
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switch(d_state) {
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case SYNC:
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d_fir->filterN(d_correlation, in, std::min(SYNC_LENGTH, std::max(ninput - 63, 0)));
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while(i + 63 < ninput) {
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d_freq_est += in[i] * conj(in[i + 16]);
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d_freq_est_buf[d_offset] = d_freq_est;
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d_cor.push_back(pair<double, int>(abs(d_correlation[i]), d_offset));
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i++;
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d_offset++;
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if(d_offset == SYNC_LENGTH) {
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search_frame_start();
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d_freq_est = d_freq_est_buf[std::max<int>(0, d_frame_start - 160 - 17)];
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d_offset = 0;
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d_state = COPY;
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mylog(boost::format("frame at %1% - freq_est (20M): %2%") % d_frame_start
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% ((arg(d_freq_est) / 16) * 20e6 / (2 * M_PI)));
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break;
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}
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}
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break;
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case COPY:
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while(i < ninput) {
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int rel = d_offset - d_frame_start;
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if( (rel >= 0) && (rel % 80 > 15)) {
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if(o >= noutput) {
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break;
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}
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if(rel == 16) {
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assert(o == 0);
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add_item_tag(0, nitems_written(0) + o,
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pmt::string_to_symbol("ofdm_start"),
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pmt::PMT_T,
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pmt::string_to_symbol(name()));
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}
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out[o] = in_delayed[i] * exp(gr_complex(0, d_offset * arg(d_freq_est) / 16));
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o++;
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}
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i++;
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d_offset++;
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}
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break;
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case RESET:
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while(o < noutput) {
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int rel = (d_offset - d_frame_start) % 80;
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if(!rel) {
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d_offset = 0;
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d_freq_est = gr_complex(0, 0);
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d_state = SYNC;
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break;
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} else if(rel > 15) {
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out[o] = 0;
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o++;
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}
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d_offset++;
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}
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break;
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default:
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std::runtime_error("bad state");
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break;
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}
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dout << "produced : " << o << " consumed: " << i << std::endl;
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consume(0, i);
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consume(1, i);
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return o;
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}
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void forecast (int noutput_items, gr_vector_int &ninput_items_required) {
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// in sync state we need at least a symbol to correlate
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// with the pattern
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if(d_state == SYNC) {
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ninput_items_required[0] = 64;
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ninput_items_required[1] = 64;
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} else {
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ninput_items_required[0] = noutput_items;
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ninput_items_required[1] = noutput_items;
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}
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}
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void search_frame_start() {
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// sort list (highest correlation first)
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assert(d_cor.size() == SYNC_LENGTH);
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d_cor.sort();
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d_cor.reverse();
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// copy list in vector for nicer access
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vector<pair<double, int> > vec(d_cor.begin(), d_cor.end());
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d_cor.clear();
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// in case we don't find anything use SYNC_LENGTH
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d_frame_start = SYNC_LENGTH;
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for(int i = 0; i < 3; i++) {
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for(int k = i + 1; k < 4; k++) {
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int diff = abs(get<1>(vec[i]) - get<1>(vec[k]));
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if(diff == 64) {
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d_frame_start = max(get<1>(vec[i]), get<1>(vec[k])) + 64;
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// nice match found, return immediately
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return;
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// TODO: check if these offsets make sense
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} else if(diff == 63) {
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d_frame_start = max(get<1>(vec[i]), get<1>(vec[k])) + 63;
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} else if(diff == 65) {
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d_frame_start = max(get<1>(vec[i]), get<1>(vec[k])) + 64;
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}
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}
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}
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}
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private:
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enum {SYNC, COPY, RESET} d_state;
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int d_offset;
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int d_frame_start;
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gr_complex d_freq_est;
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gr_complex *d_correlation;
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gr_complex *d_freq_est_buf;
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list<pair<double, int> > d_cor;
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std::vector<gr::tag_t> d_tags;
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gr::filter::kernel::fir_filter_ccc *d_fir;
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const bool d_log;
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const bool d_debug;
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const int SYNC_LENGTH;
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static const std::vector<gr_complex> LONG;
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};
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ofdm_sync_long::sptr
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ofdm_sync_long::make(unsigned int sync_length, bool log, bool debug) {
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return gnuradio::get_initial_sptr(new ofdm_sync_long_impl(sync_length, log, debug));
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}
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const std::vector<gr_complex> ofdm_sync_long_impl::LONG = {
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gr_complex( 1.3868, 0.0000), gr_complex(-0.0455, -1.0679), gr_complex( 0.3528, -0.9865), gr_complex( 0.8594, 0.7348),
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gr_complex( 0.1874, 0.2475), gr_complex( 0.5309, -0.7784), gr_complex(-1.0218, -0.4897), gr_complex(-0.3401, -0.9423),
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gr_complex( 0.8657, -0.2298), gr_complex( 0.4734, 0.0362), gr_complex( 0.0088, -1.0207), gr_complex(-1.2142, -0.4205),
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gr_complex( 0.2172, -0.5195), gr_complex( 0.5207, -0.1326), gr_complex(-0.1995, 1.4259), gr_complex( 1.0583, -0.0363),
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gr_complex( 0.5547, -0.5547), gr_complex( 0.3277, 0.8728), gr_complex(-0.5077, 0.3488), gr_complex(-1.1650, 0.5789),
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gr_complex( 0.7297, 0.8197), gr_complex( 0.6173, 0.1253), gr_complex(-0.5353, 0.7214), gr_complex(-0.5011, -0.1935),
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gr_complex(-0.3110, -1.3392), gr_complex(-1.0818, -0.1470), gr_complex(-1.1300, -0.1820), gr_complex( 0.6663, -0.6571),
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gr_complex(-0.0249, 0.4773), gr_complex(-0.8155, 1.0218), gr_complex( 0.8140, 0.9396), gr_complex( 0.1090, 0.8662),
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gr_complex(-1.3868, 0.0000), gr_complex( 0.1090, -0.8662), gr_complex( 0.8140, -0.9396), gr_complex(-0.8155, -1.0218),
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gr_complex(-0.0249, -0.4773), gr_complex( 0.6663, 0.6571), gr_complex(-1.1300, 0.1820), gr_complex(-1.0818, 0.1470),
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gr_complex(-0.3110, 1.3392), gr_complex(-0.5011, 0.1935), gr_complex(-0.5353, -0.7214), gr_complex( 0.6173, -0.1253),
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gr_complex( 0.7297, -0.8197), gr_complex(-1.1650, -0.5789), gr_complex(-0.5077, -0.3488), gr_complex( 0.3277, -0.8728),
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gr_complex( 0.5547, 0.5547), gr_complex( 1.0583, 0.0363), gr_complex(-0.1995, -1.4259), gr_complex( 0.5207, 0.1326),
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gr_complex( 0.2172, 0.5195), gr_complex(-1.2142, 0.4205), gr_complex( 0.0088, 1.0207), gr_complex( 0.4734, -0.0362),
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gr_complex( 0.8657, 0.2298), gr_complex(-0.3401, 0.9423), gr_complex(-1.0218, 0.4897), gr_complex( 0.5309, 0.7784),
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gr_complex( 0.1874, -0.2475), gr_complex( 0.8594, -0.7348), gr_complex( 0.3528, 0.9865), gr_complex(-0.0455, 1.0679)
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};
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