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KubaPro010
2025-03-10 16:50:29 +01:00
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src/fm_mpx.c Normal file
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/*
* mpxgen - FM multiplex encoder with Stereo and RDS
* Copyright (C) 2019 Anthony96922
*
* 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 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 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 "common.h"
#include "rds.h"
#ifdef RDS2
#include "rds2.h"
#endif
#include "fm_mpx.h"
#include "osc.h"
/*
* Local oscillator objects
* this is where the MPX waveforms are stored
*
*/
static struct osc_t osc_57k;
#ifdef RDS2
static struct osc_t osc_67k;
static struct osc_t osc_71k;
static struct osc_t osc_76k;
#endif
static float mpx_vol;
static uint8_t rdsgen;
void set_output_volume(float vol) {
if (vol > 100.0f) vol = 100.0f;
mpx_vol = vol / 100.0f;
}
void set_rdsgen(uint8_t gen) {
#ifdef RDS2
if (gen > 2) gen = 2;
#else
if (gen > 1) gen = 1;
#endif
rdsgen = gen;
}
/* subcarrier volumes */
static float volumes[MPX_SUBCARRIER_END] = {
0.0f, /* pilot tone: 0% */
1.0f, /* RDS: 7.5% modulation */
#ifdef RDS2
/* RDS2 */
0.05f, //66.5 khz 5%
0.05f, //71.25 khz 5%
0.0f //76 khz 0%
#endif
};
void set_carrier_volume(uint8_t carrier, float new_volume) {
/* check for valid index */
if (carrier >= MPX_SUBCARRIER_END) return;
/* don't allow levels over 15% */
if (new_volume >= 15.0f) new_volume = 15.0f;
volumes[carrier] = new_volume / 100.0f;
}
void fm_mpx_init(uint32_t sample_rate) {
/* initialize the subcarrier oscillators */
osc_init(&osc_57k, sample_rate, 57000.0f);
rdsgen = 1;
#ifdef RDS2
osc_init(&osc_67k, sample_rate, 66500.0f);
osc_init(&osc_71k, sample_rate, 71250.0f);
osc_init(&osc_76k, sample_rate, 76000.0f);
rdsgen = 2;
#endif
}
void fm_rds_get_frames(float *outbuf, size_t num_frames) {
size_t j = 0;
float out;
for (size_t i = 0; i < num_frames; i++) {
out = 0.0f;
#ifdef RDS2
out += osc_get_cos(&osc_57k)
* get_rds_sample(0, 0)
* volumes[MPX_SUBCARRIER_RDS_STREAM_0];
#else
out += get_rds_sample(0)
* volumes[MPX_SUBCARRIER_RDS_STREAM_0];
#endif
#ifdef RDS2
#ifdef RDS2_QUADRATURE_CARRIER
/* RDS2 is quadrature phase */
/* 90 degree shift */
if(rdsgen == 2 && volumes[MPX_SUBCARRIER_RDS2_STREAM_1] != 0) {
out += osc_get_sin(&osc_67k)
* get_rds_sample(1, 0)
* volumes[MPX_SUBCARRIER_RDS2_STREAM_1];
}
/* 180 degree shift */
if(rdsgen == 2 && volumes[MPX_SUBCARRIER_RDS2_STREAM_2] != 0) {
out += -osc_get_cos(&osc_71k)
* get_rds_sample(2, 0)
* volumes[MPX_SUBCARRIER_RDS2_STREAM_2];
}
/* 270 degree shift */
if(rdsgen == 2 && volumes[MPX_SUBCARRIER_RDS2_STREAM_3] != 0) {
out += -osc_get_sin(&osc_76k)
* get_rds_sample(3, 0)
* volumes[MPX_SUBCARRIER_RDS2_STREAM_3];
}
#else
if(rdsgen == 2 && volumes[MPX_SUBCARRIER_RDS2_STREAM_1] != 0) {
out += osc_get_cos(&osc_67k)
* get_rds_sample(1, 0)
* volumes[MPX_SUBCARRIER_RDS2_STREAM_1];
}
if(rdsgen == 2 && volumes[MPX_SUBCARRIER_RDS2_STREAM_1] != 0) {
out += osc_get_cos(&osc_71k)
* get_rds_sample(2, 0)
* volumes[MPX_SUBCARRIER_RDS2_STREAM_2];
}
if(rdsgen == 2 && volumes[MPX_SUBCARRIER_RDS2_STREAM_3] != 0) {
out += osc_get_cos(&osc_76k)
* get_rds_sample(3, 0)
* volumes[MPX_SUBCARRIER_RDS2_STREAM_3];
}
#endif
#endif
/* update oscillator */
osc_update_pos(&osc_57k);
#ifdef RDS2
osc_update_pos(&osc_67k);
osc_update_pos(&osc_71k);
osc_update_pos(&osc_76k);
#endif
/* declipper */
out = fminf(+1.0f, out);
out = fmaxf(-1.0f, out);
/* adjust volume and put into channel */
if(rdsgen != 0) outbuf[j] = out * mpx_vol;
j++;
}
}
void fm_mpx_exit() {
osc_exit(&osc_57k);
#ifdef RDS2
osc_exit(&osc_67k);
osc_exit(&osc_71k);
osc_exit(&osc_76k);
#endif
}