mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-13 20:01:46 -05:00
402 lines
10 KiB
C++
402 lines
10 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2023 Edouard Griffiths, F4EXB. //
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// //
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// This is the code from ft8mon: https://github.com/rtmrtmrtmrtm/ft8mon //
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// written by Robert Morris, AB1HL //
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// reformatted and adapted to Qt and SDRangel context //
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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 as 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 V3 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 <assert.h>
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#include <fftw3.h>
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#include <QDebug>
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#include "fft.h"
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#include "util.h"
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#include "ft8plan.h"
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#include "ft8plans.h"
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#include "fftbuffers.h"
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namespace FT8 {
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FFTEngine::FFTEngine()
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{
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m_fftBuffers = new FFTBuffers();
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}
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FFTEngine::~FFTEngine()
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{
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delete m_fftBuffers;
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}
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//
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// do just one FFT on samples[i0..i0+block]
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// real inputs, complex outputs.
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// output has (block / 2) + 1 points.
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//
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std::vector<std::complex<float>> FFTEngine::one_fft(
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const std::vector<float> &samples,
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int i0,
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int block
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)
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{
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// assert(i0 >= 0);
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// assert(block > 1);
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int nsamples = samples.size();
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int nbins = (block / 2) + 1;
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Plan *p = FT8Plans::GetInstance()->getPlan(block);
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fftwf_plan plan = p->fwd_;
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// assert((int)samples.size() - i0 >= block);
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float *m_in = (float *)samples.data() + i0;
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if ((((unsigned long long)m_in) % 16) != 0)
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{
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// m_in must be on a 16-byte boundary for FFTW.
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m_in = m_fftBuffers->getR(p->n_);
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// assert(m_in);
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for (int i = 0; i < block; i++)
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{
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if (i0 + i < nsamples)
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{
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m_in[i] = samples[i0 + i];
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}
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else
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{
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m_in[i] = 0;
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}
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}
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}
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fftwf_complex *m_out = m_fftBuffers->getC(p->n_);
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// assert(m_out);
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fftwf_execute_dft_r2c(plan, m_in, m_out);
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std::vector<std::complex<float>> out(nbins);
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for (int bi = 0; bi < nbins; bi++)
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{
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float re = m_out[bi][0];
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float im = m_out[bi][1];
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out[bi] = std::complex<float>(re, im);
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}
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return out;
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}
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//
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// do a full set of FFTs, one per symbol-time.
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// bins[time][frequency]
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//
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FFTEngine::ffts_t FFTEngine::ffts(const std::vector<float> &samples, int i0, int block)
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{
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// assert(i0 >= 0);
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// assert(block > 1 && (block % 2) == 0);
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int nsamples = samples.size();
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int nbins = (block / 2) + 1;
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int nblocks = (nsamples - i0) / block;
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ffts_t bins(nblocks);
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for (int si = 0; si < nblocks; si++) {
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bins[si].resize(nbins);
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}
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Plan *p = FT8Plans::GetInstance()->getPlan(block);
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fftwf_plan plan = p->fwd_;
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// allocate our own b/c using p->m_in and p->m_out isn't thread-safe.
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float *m_in = m_fftBuffers->getR(p->n_);
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fftwf_complex *m_out = m_fftBuffers->getC(p->n_);
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// assert(m_in && m_out);
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// float *m_in = p->r_;
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// fftw_complex *m_out = p->c_;
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for (int si = 0; si < nblocks; si++)
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{
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int off = i0 + si * block;
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for (int i = 0; i < block; i++)
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{
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if (off + i < nsamples)
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{
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float x = samples[off + i];
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m_in[i] = x;
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}
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else
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{
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m_in[i] = 0;
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}
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}
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fftwf_execute_dft_r2c(plan, m_in, m_out);
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for (int bi = 0; bi < nbins; bi++)
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{
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float re = m_out[bi][0];
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float im = m_out[bi][1];
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std::complex<float> c(re, im);
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bins[si][bi] = c;
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}
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}
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return bins;
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}
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//
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// do just one FFT on samples[i0..i0+block]
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// real inputs, complex outputs.
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// output has block points.
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//
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std::vector<std::complex<float>> FFTEngine::one_fft_c(
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const std::vector<float> &samples,
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int i0,
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int block
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)
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{
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// assert(i0 >= 0);
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// assert(block > 1);
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int nsamples = samples.size();
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Plan *p = FT8Plans::GetInstance()->getPlan(block);
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fftwf_plan plan = p->cfwd_;
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fftwf_complex *m_in = m_fftBuffers->getCCI(block);
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fftwf_complex *m_out = m_fftBuffers->getCCO(block);
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// assert(m_in && m_out);
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for (int i = 0; i < block; i++)
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{
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if (i0 + i < nsamples)
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{
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m_in[i][0] = samples[i0 + i]; // real
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}
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else
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{
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m_in[i][0] = 0;
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}
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m_in[i][1] = 0; // imaginary
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}
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fftwf_execute_dft(plan, m_in, m_out);
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std::vector<std::complex<float>> out(block);
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float norm = 1.0 / sqrt(block);
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for (int bi = 0; bi < block; bi++)
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{
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float re = m_out[bi][0];
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float im = m_out[bi][1];
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std::complex<float> c(re, im);
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c *= norm;
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out[bi] = c;
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}
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return out;
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}
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std::vector<std::complex<float>> FFTEngine::one_fft_cc(
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const std::vector<std::complex<float>> &samples,
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int i0,
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int block
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)
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{
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// assert(i0 >= 0);
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// assert(block > 1);
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int nsamples = samples.size();
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Plan *p = FT8Plans::GetInstance()->getPlan(block);
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fftwf_plan plan = p->cfwd_;
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fftwf_complex *m_in = m_fftBuffers->getCCI(block);
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fftwf_complex *m_out = m_fftBuffers->getCCO(block);
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// assert(m_in && m_out);
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for (int i = 0; i < block; i++)
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{
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if (i0 + i < nsamples)
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{
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m_in[i][0] = samples[i0 + i].real();
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m_in[i][1] = samples[i0 + i].imag();
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}
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else
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{
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m_in[i][0] = 0;
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m_in[i][1] = 0;
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}
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}
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fftwf_execute_dft(plan, m_in, m_out);
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std::vector<std::complex<float>> out(block);
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// float norm = 1.0 / sqrt(block);
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for (int bi = 0; bi < block; bi++)
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{
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float re = m_out[bi][0];
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float im = m_out[bi][1];
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std::complex<float> c(re, im);
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// c *= norm;
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out[bi] = c;
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}
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return out;
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}
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std::vector<std::complex<float>> FFTEngine::one_ifft_cc(
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const std::vector<std::complex<float>> &bins
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)
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{
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int block = bins.size();
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Plan *p = FT8Plans::GetInstance()->getPlan(block);
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fftwf_plan plan = p->crev_;
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fftwf_complex *m_in = m_fftBuffers->getCCI(block);
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fftwf_complex *m_out = m_fftBuffers->getCCO(block);
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// assert(m_in && m_out);
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for (int bi = 0; bi < block; bi++)
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{
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float re = bins[bi].real();
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float im = bins[bi].imag();
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m_in[bi][0] = re;
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m_in[bi][1] = im;
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}
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fftwf_execute_dft(plan, m_in, m_out);
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std::vector<std::complex<float>> out(block);
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float norm = 1.0 / sqrt(block);
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for (int i = 0; i < block; i++)
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{
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float re = m_out[i][0];
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float im = m_out[i][1];
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std::complex<float> c(re, im);
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c *= norm;
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out[i] = c;
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}
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return out;
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}
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std::vector<float> FFTEngine::one_ifft(const std::vector<std::complex<float>> &bins)
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{
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int nbins = bins.size();
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int block = (nbins - 1) * 2;
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Plan *p = FT8Plans::GetInstance()->getPlan(block);
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fftwf_plan plan = p->rev_;
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fftwf_complex *m_in = m_fftBuffers->getC(p->n_);
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float *m_out = m_fftBuffers->getR(p->n_);
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for (int bi = 0; bi < nbins; bi++)
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{
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float re = bins[bi].real();
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float im = bins[bi].imag();
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m_in[bi][0] = re;
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m_in[bi][1] = im;
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}
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fftwf_execute_dft_c2r(plan, m_in, m_out);
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std::vector<float> out(block);
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for (int i = 0; i < block; i++)
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{
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out[i] = m_out[i];
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}
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return out;
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}
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//
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// return the analytic signal for signal x,
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// just like scipy.signal.hilbert(), from which
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// this code is copied.
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//
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// the return value is x + iy, where y is the hilbert transform of x.
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//
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std::vector<std::complex<float>> FFTEngine::analytic(const std::vector<float> &x)
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{
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ulong n = x.size();
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std::vector<std::complex<float>> y = one_fft_c(x, 0, n);
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// assert(y.size() == n);
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// leave y[0] alone.
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// float the first (positive) half of the spectrum.
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// zero out the second (negative) half of the spectrum.
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// y[n/2] is the nyquist bucket if n is even; leave it alone.
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if ((n % 2) == 0)
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{
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for (ulong i = 1; i < n / 2; i++)
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y[i] *= 2;
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for (ulong i = n / 2 + 1; i < n; i++)
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y[i] = 0;
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}
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else
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{
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for (ulong i = 1; i < (n + 1) / 2; i++)
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y[i] *= 2;
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for (ulong i = (n + 1) / 2; i < n; i++)
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y[i] = 0;
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}
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std::vector<std::complex<float>> z = one_ifft_cc(y);
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return z;
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}
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//
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// general-purpose shift x in frequency by hz.
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// uses hilbert transform to avoid sidebands.
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// but it does wrap around at 0 hz and the nyquist frequency.
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//
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// note analytic() does an FFT over the whole signal, which
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// is expensive, and often re-used, but it turns out it
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// isn't a big factor in overall run-time.
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//
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// like weakutil.py's freq_shift().
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//
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std::vector<float> FFTEngine::hilbert_shift(const std::vector<float> &x, float hz0, float hz1, int rate)
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{
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// y = scipy.signal.hilbert(x)
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std::vector<std::complex<float>> y = analytic(x);
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// assert(y.size() == x.size());
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float dt = 1.0 / rate;
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int n = x.size();
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std::vector<float> ret(n);
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for (int i = 0; i < n; i++)
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{
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// complex "local oscillator" at hz.
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float hz = hz0 + (i / (float)n) * (hz1 - hz0);
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std::complex<float> lo = std::exp(std::complex<float>(0.0, 2 * M_PI * hz * dt * i));
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ret[i] = (lo * y[i]).real();
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}
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return ret;
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}
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} // namespace FT8
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