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112 lines
3.5 KiB
C++
112 lines
3.5 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2018 F4EXB //
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// written by Edouard Griffiths //
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// //
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// FFT based cross correlation //
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// //
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// See: http://liquidsdr.org/blog/pll-howto/ //
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// Fixed filter registers saturation //
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// Added order for PSK locking. This brilliant idea actually comes from this //
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// post: https://www.dsprelated.com/showthread/comp.dsp/36356-1.php //
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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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// //
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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 <algorithm>
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#include "fftcorr.h"
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void fftcorr::init_fft()
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{
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fftA = new g_fft<float>(flen);
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fftB = new g_fft<float>(flen);
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dataA = new cmplx[flen];
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dataB = new cmplx[flen];
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dataBj = new cmplx[flen];
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dataP = new cmplx[flen];
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std::fill(dataA, dataA+flen, 0);
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std::fill(dataB, dataB+flen, 0);
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inptrA = 0;
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inptrB = 0;
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outptr = 0;
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}
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fftcorr::fftcorr(int len) : flen(len), flen2(len>>1)
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{
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init_fft();
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}
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fftcorr::~fftcorr()
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{
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delete fftA;
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delete fftB;
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delete[] dataA;
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delete[] dataB;
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delete[] dataBj;
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delete[] dataP;
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}
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int fftcorr::run(const cmplx& inA, const cmplx* inB, cmplx **out)
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{
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dataA[inptrA++] = inA;
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if (inB) {
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dataB[inptrB++] = *inB;
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}
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if (inptrA < flen2) {
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return 0;
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}
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fftA->ComplexFFT(dataA);
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if (inB) {
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fftB->ComplexFFT(dataB);
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}
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if (inB) {
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std::transform(dataB, dataB+flen, dataBj, [](const cmplx& c) -> cmplx { return std::conj(c); });
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} else {
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std::transform(dataA, dataA+flen, dataBj, [](const cmplx& c) -> cmplx { return std::conj(c); });
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}
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std::transform(dataA, dataA+flen, dataBj, dataP, [](const cmplx& a, const cmplx& b) -> cmplx { return a*b; });
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fftA->InverseComplexFFT(dataP);
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std::fill(dataA, dataA+flen, 0);
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inptrA = 0;
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if (inB)
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{
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std::fill(dataB, dataB+flen, 0);
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inptrB = 0;
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}
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*out = dataP;
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return flen2;
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}
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const fftcorr::cmplx& fftcorr::run(const cmplx& inA, const cmplx* inB)
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{
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cmplx *dummy;
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if (run(inA, inB, &dummy)) {
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outptr = 0;
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}
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return dataP[outptr++];
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}
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