mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-16 05:11:49 -05:00
342 lines
9.9 KiB
C++
342 lines
9.9 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2023 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
|
|
// //
|
|
// This is the code from ft8mon: https://github.com/rtmrtmrtmrtm/ft8mon //
|
|
// reformatted and adapted to Qt and SDRangel context //
|
|
// //
|
|
// 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 <math.h>
|
|
#include <complex>
|
|
#include <string>
|
|
#include <algorithm>
|
|
|
|
#include "util/timeutil.h"
|
|
#include "util.h"
|
|
|
|
namespace FT8 {
|
|
|
|
double now()
|
|
{
|
|
return TimeUtil::nowus() / 1000000.0;
|
|
}
|
|
|
|
//
|
|
// Goertzel Algorithm for a Non-integer Frequency Index, Rick Lyons
|
|
// https://www.dsprelated.com/showarticle/495.php
|
|
//
|
|
std::complex<float> goertzel(std::vector<float> v, int rate, int i0, int n, float hz)
|
|
{
|
|
// float radians_per_sample = (hz * 2 * M_PI) / rate;
|
|
// float k = radians_per_sample * n;
|
|
float bin_hz = rate / (float)n;
|
|
float k = hz / bin_hz;
|
|
|
|
float alpha = 2 * M_PI * k / n;
|
|
float beta = 2 * M_PI * k * (n - 1.0) / n;
|
|
|
|
float two_cos_alpha = 2 * cos(alpha);
|
|
float a = cos(beta);
|
|
float b = -sin(beta);
|
|
float c = sin(alpha) * sin(beta) - cos(alpha) * cos(beta);
|
|
float d = sin(2 * M_PI * k);
|
|
|
|
float w1 = 0;
|
|
float w2 = 0;
|
|
|
|
for (int i = 0; i < n; i++)
|
|
{
|
|
float w0 = v[i0 + i] + two_cos_alpha * w1 - w2;
|
|
w2 = w1;
|
|
w1 = w0;
|
|
}
|
|
|
|
float re = w1 * a + w2 * c;
|
|
float im = w1 * b + w2 * d;
|
|
|
|
return std::complex<float>(re, im);
|
|
}
|
|
|
|
float vmax(const std::vector<float> &v)
|
|
{
|
|
float mx = 0;
|
|
int got = 0;
|
|
for (int i = 0; i < (int)v.size(); i++)
|
|
{
|
|
if (got == 0 || v[i] > mx)
|
|
{
|
|
got = 1;
|
|
mx = v[i];
|
|
}
|
|
}
|
|
return mx;
|
|
}
|
|
|
|
std::vector<float> vreal(const std::vector<std::complex<float>> &a)
|
|
{
|
|
std::vector<float> b(a.size());
|
|
for (int i = 0; i < (int)a.size(); i++)
|
|
{
|
|
b[i] = a[i].real();
|
|
}
|
|
return b;
|
|
}
|
|
|
|
std::vector<float> vimag(const std::vector<std::complex<float>> &a)
|
|
{
|
|
std::vector<float> b(a.size());
|
|
for (int i = 0; i < (int)a.size(); i++)
|
|
{
|
|
b[i] = a[i].imag();
|
|
}
|
|
return b;
|
|
}
|
|
|
|
// generate 8-FSK, at 25 hz, bin size 6.25 hz,
|
|
// 200 samples/second, 32 samples/symbol.
|
|
// used as reference to detect pairs of symbols.
|
|
// superseded by gfsk().
|
|
std::vector<std::complex<float>> fsk_c(const std::vector<int> &syms)
|
|
{
|
|
int n = syms.size();
|
|
std::vector<std::complex<float>> v(n * 32);
|
|
float theta = 0;
|
|
for (int si = 0; si < n; si++)
|
|
{
|
|
float hz = 25 + syms[si] * 6.25;
|
|
for (int i = 0; i < 32; i++)
|
|
{
|
|
v[si * 32 + i] = std::complex<float>(cos(theta), sin(theta));
|
|
theta += 2 * M_PI / (200 / hz);
|
|
}
|
|
}
|
|
return v;
|
|
}
|
|
|
|
// copied from wsjt-x ft2/gfsk_pulse.f90.
|
|
// b is 1.0 for FT4; 2.0 for FT8.
|
|
float gfsk_point(float b, float t)
|
|
{
|
|
float c = M_PI * sqrt(2.0 / log(2.0));
|
|
float x = 0.5 * (erf(c * b * (t + 0.5)) - erf(c * b * (t - 0.5)));
|
|
return x;
|
|
}
|
|
|
|
// the smoothing window for gfsk.
|
|
// run the window over impulses of symbol frequencies,
|
|
// each impulse at the center of its symbol time.
|
|
// three symbols wide.
|
|
// most of the pulse is in the center symbol.
|
|
// b is 1.0 for FT4; 2.0 for FT8.
|
|
std::vector<float> gfsk_window(int samples_per_symbol, float b)
|
|
{
|
|
std::vector<float> v(3 * samples_per_symbol);
|
|
float sum = 0;
|
|
for (int i = 0; i < (int)v.size(); i++)
|
|
{
|
|
float x = i / (float)samples_per_symbol;
|
|
x -= 1.5;
|
|
float y = gfsk_point(b, x);
|
|
v[i] = y;
|
|
sum += y;
|
|
}
|
|
|
|
for (int i = 0; i < (int)v.size(); i++)
|
|
{
|
|
v[i] /= sum;
|
|
}
|
|
|
|
return v;
|
|
}
|
|
|
|
// gaussian-smoothed fsk.
|
|
// the gaussian smooths the instantaneous frequencies,
|
|
// so that the transitions between symbols don't
|
|
// cause clicks.
|
|
// gwin is gfsk_window(32, 2.0)
|
|
std::vector<std::complex<float>> gfsk_c(
|
|
const std::vector<int> &symbols,
|
|
float hz0, float hz1,
|
|
float spacing, int rate, int symsamples,
|
|
float phase0,
|
|
const std::vector<float> &gwin
|
|
)
|
|
{
|
|
if (!((gwin.size() % 2) == 0))
|
|
{
|
|
std::vector<std::complex<float>> v(symsamples * symbols.size());
|
|
return v;
|
|
}
|
|
|
|
// compute frequency for each symbol.
|
|
// generate a spike in the middle of each symbol time;
|
|
// the gaussian filter will turn it into a waveform.
|
|
std::vector<float> hzv(symsamples * (symbols.size() + 2), 0.0);
|
|
for (int bi = 0; bi < (int)symbols.size(); bi++)
|
|
{
|
|
float base_hz = hz0 + (hz1 - hz0) * (bi / (float)symbols.size());
|
|
float fr = base_hz + (symbols[bi] * spacing);
|
|
int mid = symsamples * (bi + 1) + symsamples / 2;
|
|
// the window has even size, so split the impulse over
|
|
// the two middle samples to be symmetric.
|
|
hzv[mid] = fr * symsamples / 2.0;
|
|
hzv[mid - 1] = fr * symsamples / 2.0;
|
|
}
|
|
|
|
// repeat first and last symbols
|
|
for (int i = 0; i < symsamples; i++)
|
|
{
|
|
hzv[i] = hzv[i + symsamples];
|
|
hzv[symsamples * (symbols.size() + 1) + i] = hzv[symsamples * symbols.size() + i];
|
|
}
|
|
|
|
// run the per-sample frequency vector through
|
|
// the gaussian filter.
|
|
int half = gwin.size() / 2;
|
|
std::vector<float> o(hzv.size());
|
|
for (int i = 0; i < (int)o.size(); i++)
|
|
{
|
|
float sum = 0;
|
|
for (int j = 0; j < (int)gwin.size(); j++)
|
|
{
|
|
int k = i - half + j;
|
|
if (k >= 0 && k < (int)hzv.size())
|
|
{
|
|
sum += hzv[k] * gwin[j];
|
|
}
|
|
}
|
|
o[i] = sum;
|
|
}
|
|
|
|
// drop repeated first and last symbols
|
|
std::vector<float> oo(symsamples * symbols.size());
|
|
for (int i = 0; i < (int)oo.size(); i++)
|
|
{
|
|
oo[i] = o[i + symsamples];
|
|
}
|
|
|
|
// now oo[i] contains the frequency for the i'th sample.
|
|
|
|
std::vector<std::complex<float>> v(symsamples * symbols.size());
|
|
float theta = phase0;
|
|
for (int i = 0; i < (int)v.size(); i++)
|
|
{
|
|
v[i] = std::complex<float>(cos(theta), sin(theta));
|
|
float hz = oo[i];
|
|
theta += 2 * M_PI / (rate / hz);
|
|
}
|
|
|
|
return v;
|
|
}
|
|
|
|
// gaussian-smoothed fsk.
|
|
// the gaussian smooths the instantaneous frequencies,
|
|
// so that the transitions between symbols don't
|
|
// cause clicks.
|
|
// gwin is gfsk_window(32, 2.0)
|
|
std::vector<float> gfsk_r(
|
|
const std::vector<int> &symbols,
|
|
float hz0, float hz1,
|
|
float spacing, int rate, int symsamples,
|
|
float phase0,
|
|
const std::vector<float> &gwin
|
|
)
|
|
{
|
|
if (!((gwin.size() % 2) == 0))
|
|
{
|
|
std::vector<float> v(symsamples * symbols.size());
|
|
return v;
|
|
}
|
|
|
|
// compute frequency for each symbol.
|
|
// generate a spike in the middle of each symbol time;
|
|
// the gaussian filter will turn it into a waveform.
|
|
std::vector<float> hzv(symsamples * (symbols.size() + 2), 0.0);
|
|
for (int bi = 0; bi < (int)symbols.size(); bi++)
|
|
{
|
|
float base_hz = hz0 + (hz1 - hz0) * (bi / (float)symbols.size());
|
|
float fr = base_hz + (symbols[bi] * spacing);
|
|
int mid = symsamples * (bi + 1) + symsamples / 2;
|
|
// the window has even size, so split the impulse over
|
|
// the two middle samples to be symmetric.
|
|
hzv[mid] = fr * symsamples / 2.0;
|
|
hzv[mid - 1] = fr * symsamples / 2.0;
|
|
}
|
|
|
|
// repeat first and last symbols
|
|
for (int i = 0; i < symsamples; i++)
|
|
{
|
|
hzv[i] = hzv[i + symsamples];
|
|
hzv[symsamples * (symbols.size() + 1) + i] = hzv[symsamples * symbols.size() + i];
|
|
}
|
|
|
|
// run the per-sample frequency vector through
|
|
// the gaussian filter.
|
|
int half = gwin.size() / 2;
|
|
std::vector<float> o(hzv.size());
|
|
for (int i = 0; i < (int)o.size(); i++)
|
|
{
|
|
float sum = 0;
|
|
for (int j = 0; j < (int)gwin.size(); j++)
|
|
{
|
|
int k = i - half + j;
|
|
if (k >= 0 && k < (int)hzv.size())
|
|
{
|
|
sum += hzv[k] * gwin[j];
|
|
}
|
|
}
|
|
o[i] = sum;
|
|
}
|
|
|
|
// drop repeated first and last symbols
|
|
std::vector<float> oo(symsamples * symbols.size());
|
|
for (int i = 0; i < (int)oo.size(); i++)
|
|
{
|
|
oo[i] = o[i + symsamples];
|
|
}
|
|
|
|
// now oo[i] contains the frequency for the i'th sample.
|
|
|
|
std::vector<float> v(symsamples * symbols.size());
|
|
float theta = phase0;
|
|
for (int i = 0; i < (int)v.size(); i++)
|
|
{
|
|
v[i] = cos(theta);
|
|
float hz = oo[i];
|
|
theta += 2 * M_PI / (rate / hz);
|
|
}
|
|
|
|
return v;
|
|
}
|
|
|
|
const std::string WHITESPACE = " \n\r\t\f\v";
|
|
|
|
std::string ltrim(const std::string &s)
|
|
{
|
|
size_t start = s.find_first_not_of(WHITESPACE);
|
|
return (start == std::string::npos) ? "" : s.substr(start);
|
|
}
|
|
|
|
std::string rtrim(const std::string &s)
|
|
{
|
|
size_t end = s.find_last_not_of(WHITESPACE);
|
|
return (end == std::string::npos) ? "" : s.substr(0, end + 1);
|
|
}
|
|
|
|
std::string trim(const std::string &s) {
|
|
return rtrim(ltrim(s));
|
|
}
|
|
|
|
} // namespace FT8
|