mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-17 22:01:45 -05:00
113 lines
3.6 KiB
C++
113 lines
3.6 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2018 F4EXB //
|
|
// written by Edouard Griffiths //
|
|
// //
|
|
// FFT based cross correlation //
|
|
// //
|
|
// See: http://liquidsdr.org/blog/pll-howto/ //
|
|
// Fixed filter registers saturation //
|
|
// Added order for PSK locking. This brilliant idea actually comes from this //
|
|
// post: https://www.dsprelated.com/showthread/comp.dsp/36356-1.php //
|
|
// //
|
|
// This program 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 as version 3 of the License, or //
|
|
// (at your option) any later version. //
|
|
// //
|
|
// This program 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 V3 for more details. //
|
|
// //
|
|
// You should have received a copy of the GNU General Public License //
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#include <algorithm>
|
|
#include "fftcorr.h"
|
|
|
|
void fftcorr::init_fft()
|
|
{
|
|
fftA = new g_fft<float>(flen);
|
|
fftB = new g_fft<float>(flen);
|
|
|
|
dataA = new cmplx[flen];
|
|
dataB = new cmplx[flen];
|
|
dataBj = new cmplx[flen];
|
|
dataP = new cmplx[flen];
|
|
|
|
std::fill(dataA, dataA+flen, 0);
|
|
std::fill(dataB, dataB+flen, 0);
|
|
|
|
inptrA = 0;
|
|
inptrB = 0;
|
|
outptr = 0;
|
|
}
|
|
|
|
fftcorr::fftcorr(int len) : flen(len), flen2(len>>1)
|
|
{
|
|
init_fft();
|
|
}
|
|
|
|
fftcorr::~fftcorr()
|
|
{
|
|
delete fftA;
|
|
delete fftB;
|
|
delete[] dataA;
|
|
delete[] dataB;
|
|
delete[] dataBj;
|
|
delete[] dataP;
|
|
}
|
|
|
|
int fftcorr::run(const cmplx& inA, const cmplx* inB, cmplx **out)
|
|
{
|
|
dataA[inptrA++] = inA;
|
|
|
|
if (inB) {
|
|
dataB[inptrB++] = *inB;
|
|
}
|
|
|
|
if (inptrA < flen2) {
|
|
return 0;
|
|
}
|
|
|
|
fftA->ComplexFFT(dataA);
|
|
|
|
if (inB) {
|
|
fftB->ComplexFFT(dataB);
|
|
}
|
|
|
|
if (inB) {
|
|
std::transform(dataB, dataB+flen, dataBj, [](const cmplx& c) -> cmplx { return std::conj(c); });
|
|
} else {
|
|
std::transform(dataA, dataA+flen, dataBj, [](const cmplx& c) -> cmplx { return std::conj(c); });
|
|
}
|
|
|
|
std::transform(dataA, dataA+flen, dataBj, dataP, [](const cmplx& a, const cmplx& b) -> cmplx { return a*b; });
|
|
|
|
fftA->InverseComplexFFT(dataP);
|
|
|
|
std::fill(dataA, dataA+flen, 0);
|
|
inptrA = 0;
|
|
|
|
if (inB)
|
|
{
|
|
std::fill(dataB, dataB+flen, 0);
|
|
inptrB = 0;
|
|
}
|
|
|
|
*out = dataP;
|
|
return flen2;
|
|
}
|
|
|
|
const fftcorr::cmplx& fftcorr::run(const cmplx& inA, const cmplx* inB)
|
|
{
|
|
cmplx *dummy;
|
|
|
|
if (run(inA, inB, &dummy)) {
|
|
outptr = 0;
|
|
}
|
|
|
|
return dataP[outptr++];
|
|
}
|