portapack-mayhem/firmware/baseband/dsp_modulate.cpp

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/*
* Copyright (C) 2020 Belousov Oleg
*
* This file is part of PortaPack.
*
* 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, 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; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "dsp_modulate.hpp"
#include "sine_table_int8.hpp"
namespace dsp {
namespace modulate {
Modulator::~Modulator() {
}
Mode Modulator::get_mode() {
return mode;
}
void Modulator::set_mode(Mode new_mode) {
mode = new_mode;
}
void Modulator::set_over(uint32_t new_over) {
over = new_over;
}
///
SSB::SSB() : hilbert() {
mode = Mode::LSB;
}
void SSB::execute(const buffer_s16_t& audio, const buffer_c8_t& buffer) {
int32_t sample = 0;
int8_t re = 0, im = 0;
for (size_t counter = 0; counter < buffer.count; counter++) {
if (counter % 128 == 0) {
float i = 0.0, q = 0.0;
sample = audio.p[counter / over] >> 2;
//switch (mode) {
//case Mode::LSB:
hilbert.execute(sample / 32768.0f, i, q);
//case Mode::USB: hilbert.execute(sample / 32768.0f, q, i);
//default: break;
//}
i *= 256.0f; // Original 64.0f, now x 4 (+12 dB's SSB BB modulation)
q *= 256.0f; // Original 64.0f, now x 4 (+12 dB's SSB BB modulation)
switch (mode) {
case Mode::LSB: re = q; im = i; break;
case Mode::USB: re = i; im = q; break;
default: re = 0; im = 0; break;
}
//re = q;
//im = i;
//break;
}
buffer.p[counter] = { re, im };
}
}
///
FM::FM() {
mode = Mode::FM;
}
void FM::set_fm_delta(uint32_t new_delta) {
fm_delta = new_delta;
}
void FM::execute(const buffer_s16_t& audio, const buffer_c8_t& buffer) {
int32_t sample = 0;
int8_t re, im;
for (size_t counter = 0; counter < buffer.count; counter++) {
if (counter % over == 0) {
sample = audio.p[counter / over] >> 8;
delta = sample * fm_delta;
}
phase += delta;
sphase = phase >> 24;
re = (sine_table_i8[(sphase + 64) & 255]);
im = (sine_table_i8[sphase]);
buffer.p[counter] = { re, im };
}
}
AM::AM() {
mode = Mode::AM;
}
void AM::execute(const buffer_s16_t& audio, const buffer_c8_t& buffer) {
int32_t sample = 0;
int8_t re = 0, im = 0;
float q = 0.0;
for (size_t counter = 0; counter < buffer.count; counter++) {
if (counter % 128 == 0) {
sample = audio.p[counter / over] >> 2;
}
q = sample / 32768.0f;
q *= 256.0f; // Original 64.0f,now x4 (+12 dB's BB_modulation in AM & DSB)
switch (mode) {
case Mode::AM: re = q + 80; im = q + 80; break; // Original DC add +20_DC_level=carrier,now x4 (+12dB's AM carrier)
case Mode::DSB: re = q; im = q; break;
default: break;
}
buffer.p[counter] = { re, im };
}
}
}
}