void NarrowbandFMAudio::execute(buffer_c8_t buffer) {
/* Called every 2048/3072000 second -- 1500Hz. */
auto decimator_out = decimator.execute(buffer);
const buffer_c16_t work_baseband_buffer {
(complex16_t*)decimator_out.p,
sizeof(*decimator_out.p) * decimator_out.count
};
/* 96kHz complex<int16_t>[64]
* -> FIR filter, <6kHz (0.063fs) pass, gain 1.0
* -> 48kHz int16_t[32] */
auto channel = channel_filter.execute(decimator_out, work_baseband_buffer);
// TODO: Feed channel_stats post-decimation data?
feed_channel_stats(channel);
feed_channel_spectrum(
channel,
decimator_out.sampling_rate * channel_filter_taps.pass_frequency_normalized,
decimator_out.sampling_rate * channel_filter_taps.stop_frequency_normalized
);
const buffer_s16_t work_audio_buffer {
(int16_t*)decimator_out.p,
sizeof(*decimator_out.p) * decimator_out.count
};
/* 48kHz complex<int16_t>[32]
* -> FM demodulation
* -> 48kHz int16_t[32] */
auto audio = demod.execute(channel, work_audio_buffer);
static uint64_t audio_present_history = 0;
const auto audio_present_now = squelch.execute(audio);
audio_present_history = (audio_present_history << 1) | (audio_present_now ? 1 : 0);
const bool audio_present = (audio_present_history != 0);
if( !audio_present ) {
// Zero audio buffer.
for(size_t i=0; i<audio.count; i++) {
audio.p[i] = 0;
}
}
audio_hpf.execute_in_place(audio);
fill_audio_buffer(audio);
}
void AISProcessor::execute(const buffer_c8_t& buffer) {
/* 2.4576MHz, 2048 samples */
const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
const auto decim_1_out = decim_1.execute(decim_0_out, dst_buffer);
const auto decimator_out = decim_1_out;
/* 38.4kHz, 32 samples */
feed_channel_stats(decimator_out);
for(size_t i=0; i<decimator_out.count; i++) {
if( mf.execute_once(decimator_out.p[i]) ) {
clock_recovery(mf.get_output());
}
}
}
void NarrowbandAMAudio::execute(const buffer_c8_t& buffer) {
if( !configured ) {
return;
}
const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
const auto decim_1_out = decim_1.execute(decim_0_out, dst_buffer);
const auto channel_out = channel_filter.execute(decim_1_out, dst_buffer);
// TODO: Feed channel_stats post-decimation data?
feed_channel_stats(channel_out);
channel_spectrum.feed(channel_out, channel_filter_pass_f, channel_filter_stop_f);
auto audio = demod.execute(channel_out, work_audio_buffer);
audio_output.write(audio);
}
void WidebandFMAudio::execute(const buffer_c8_t& buffer) {
if( !configured ) {
return;
}
const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
const auto channel = decim_1.execute(decim_0_out, dst_buffer);
// TODO: Feed channel_stats post-decimation data?
feed_channel_stats(channel);
spectrum_samples += channel.count;
if( spectrum_samples >= spectrum_interval_samples ) {
spectrum_samples -= spectrum_interval_samples;
channel_spectrum.feed(channel, channel_filter_pass_f, channel_filter_stop_f);
}
/* 384kHz complex<int16_t>[256]
* -> FM demodulation
* -> 384kHz int16_t[256] */
/* TODO: To improve adjacent channel rejection, implement complex channel filter:
* pass < +/- 100kHz, stop > +/- 200kHz
*/
auto audio_oversampled = demod.execute(channel, work_audio_buffer);
/* 384kHz int16_t[256]
* -> 4th order CIC decimation by 2, gain of 1
* -> 192kHz int16_t[128] */
auto audio_4fs = audio_dec_1.execute(audio_oversampled, work_audio_buffer);
/* 192kHz int16_t[128]
* -> 4th order CIC decimation by 2, gain of 1
* -> 96kHz int16_t[64] */
auto audio_2fs = audio_dec_2.execute(audio_4fs, work_audio_buffer);
/* 96kHz int16_t[64]
* -> FIR filter, <15kHz (0.156fs) pass, >19kHz (0.198fs) stop, gain of 1
* -> 48kHz int16_t[32] */
auto audio = audio_filter.execute(audio_2fs, work_audio_buffer);
/* -> 48kHz int16_t[32] */
audio_output.write(audio);
}
void CaptureProcessor::execute(const buffer_c8_t& buffer) {
/* 2.4576MHz, 2048 samples */
const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
const auto decim_1_out = decim_1.execute(decim_0_out, dst_buffer);
const auto& decimator_out = decim_1_out;
const auto& channel = decimator_out;
if( stream ) {
const size_t bytes_to_write = sizeof(*decimator_out.p) * decimator_out.count;
const auto result = stream->write(decimator_out.p, bytes_to_write);
}
feed_channel_stats(channel);
spectrum_samples += channel.count;
if( spectrum_samples >= spectrum_interval_samples ) {
spectrum_samples -= spectrum_interval_samples;
channel_spectrum.feed(channel, channel_filter_pass_f, channel_filter_stop_f);
}
}
