2020-11-05 13:11:57 -05:00
|
|
|
/*
|
|
|
|
* High Speed modem to transfer data in a 2,7kHz SSB channel
|
|
|
|
* =========================================================
|
|
|
|
* Author: DJ0ABR
|
|
|
|
*
|
|
|
|
* (c) DJ0ABR
|
|
|
|
* www.dj0abr.de
|
|
|
|
*
|
|
|
|
* 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; either version 2 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 for more details.
|
|
|
|
*
|
|
|
|
* You should have received a copy of the GNU General Public License
|
|
|
|
* along with this program; if not, write to the Free Software
|
|
|
|
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
|
|
*
|
|
|
|
*/
|
|
|
|
|
|
|
|
#include "hsmodem.h"
|
|
|
|
#ifdef _WIN32_
|
|
|
|
#include "fftw_lib/fftw3.h"
|
|
|
|
#endif
|
|
|
|
#ifdef _LINUX_
|
|
|
|
#include <fftw3.h>
|
|
|
|
#endif
|
|
|
|
|
|
|
|
#define FFT_AUDIOSAMPLERATE 8000
|
|
|
|
|
|
|
|
double *din = NULL; // input data for fft
|
|
|
|
fftw_complex *cpout = NULL; // ouput data from fft
|
|
|
|
fftw_plan plan = NULL;
|
|
|
|
#define fft_rate (FFT_AUDIOSAMPLERATE / 10) // resolution: 10 Hz
|
|
|
|
int fftidx = 0;
|
|
|
|
int fftcnt = fft_rate/2+1; // number of output values
|
|
|
|
uint16_t fftout[FFT_AUDIOSAMPLERATE / 10/2+1];
|
|
|
|
int downsamp = 0;
|
|
|
|
int downphase = 0;
|
|
|
|
|
|
|
|
uint16_t *make_waterfall(float fre, int *retlen)
|
|
|
|
{
|
|
|
|
// Downsampling:
|
|
|
|
// needed 8000 bit/s
|
|
|
|
// caprate 48k: downsample by 6
|
|
|
|
// caprate 44,1k: downsample by 5,5
|
|
|
|
|
|
|
|
if (caprate == 48000)
|
|
|
|
{
|
|
|
|
if (++downsamp < 6) return NULL;
|
|
|
|
}
|
|
|
|
if (caprate == 44100)
|
|
|
|
{
|
|
|
|
if (downphase <= 1100)
|
|
|
|
{
|
|
|
|
if (++downsamp < 5) return NULL;
|
|
|
|
}
|
|
|
|
else
|
|
|
|
{
|
|
|
|
if (++downsamp < 6) return NULL;
|
|
|
|
}
|
|
|
|
if(++downphase >= 2000) downphase = 0;
|
|
|
|
}
|
|
|
|
downsamp = 0;
|
|
|
|
|
|
|
|
int fftrdy = 0;
|
|
|
|
|
|
|
|
// fre are the float samples
|
|
|
|
// fill into the fft input buffer
|
|
|
|
din[fftidx++] = fre;
|
|
|
|
|
|
|
|
if(fftidx == fft_rate)
|
|
|
|
{
|
|
|
|
fftidx = 0;
|
|
|
|
|
|
|
|
// the fft buffer is full, execute the FFT
|
|
|
|
fftw_execute(plan);
|
|
|
|
|
|
|
|
for (int j = 0; j < fftcnt; j++)
|
|
|
|
{
|
|
|
|
// calculate absolute value (magnitute without phase)
|
|
|
|
float fre = (float)cpout[j][0];
|
|
|
|
float fim = (float)cpout[j][1];
|
|
|
|
float mag = sqrt((fre * fre) + (fim * fim));
|
|
|
|
|
|
|
|
fftout[j] = (uint16_t)mag;
|
|
|
|
|
|
|
|
fftrdy = 1;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
if(fftrdy == 1)
|
|
|
|
{
|
|
|
|
*retlen = fftcnt;
|
|
|
|
return fftout;
|
|
|
|
}
|
|
|
|
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
void init_fft()
|
|
|
|
{
|
2020-11-21 13:54:47 -05:00
|
|
|
/*
|
2020-11-05 13:11:57 -05:00
|
|
|
char fn[300];
|
2020-11-21 13:54:47 -05:00
|
|
|
* storing to a file in the working directory may be a problem under Windows, so we do not use wisdom files
|
|
|
|
sprintf(fn, "capture_fft_%d", fft_rate); // wisdom file for each capture rate
|
2020-11-05 13:11:57 -05:00
|
|
|
|
2020-11-21 13:54:47 -05:00
|
|
|
fftw_import_wisdom_from_filename(fn);*/
|
2020-11-05 13:11:57 -05:00
|
|
|
|
|
|
|
din = (double *)fftw_malloc(sizeof(double) * fft_rate);
|
|
|
|
cpout = (fftw_complex *)fftw_malloc(sizeof(fftw_complex) * fft_rate);
|
|
|
|
|
|
|
|
plan = fftw_plan_dft_r2c_1d(fft_rate, din, cpout, FFTW_MEASURE);
|
|
|
|
|
2020-11-21 13:54:47 -05:00
|
|
|
//fftw_export_wisdom_to_filename(fn);
|
2020-11-05 13:11:57 -05:00
|
|
|
}
|
|
|
|
|
|
|
|
void exit_fft()
|
|
|
|
{
|
|
|
|
if(plan) fftw_destroy_plan(plan);
|
|
|
|
if(din) fftw_free(din);
|
|
|
|
if(cpout) fftw_free(cpout);
|
|
|
|
}
|