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sdrangel/modemm17/M17Demodulator.cpp
f4exb ac2a45ce88 M17 code reorganization
2022-07-20 05:47:48 +02:00

599 lines
18 KiB
C++
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#include <QDebug>
#include <QString>
#include "M17Demodulator.h"
namespace modemm17 {
// const std::array<float, 150> M17Demodulator::rrc_taps = std::array<float, 150>{
// 0.0029364388513841593, 0.0031468394550958484, 0.002699564567597445, 0.001661182944400927, 0.00023319405581230247,
// -0.0012851320781224025, -0.0025577136087664687, -0.0032843366522956313, -0.0032697038088887226, -0.0024733964729590865,
// -0.0010285696910973807, 0.0007766690889758685, 0.002553421969211845, 0.0038920145144327816, 0.004451886520053017,
// 0.00404219185231544, 0.002674727068399207, 0.0005756567993179152, -0.0018493784971116507, -0.004092346891623224,
// -0.005648131453822014, -0.006126925416243605, -0.005349511529163396, -0.003403189203405097, -0.0006430502751187517,
// 0.002365929161655135, 0.004957956568090113, 0.006506845894531803, 0.006569574194782443, 0.0050017573119839134,
// 0.002017321931508163, -0.0018256054303579805, -0.00571615173291049, -0.008746639552588416, -0.010105075751866371,
// -0.009265784007800534, -0.006136551625729697, -0.001125978562075172, 0.004891777252042491, 0.01071805138282269,
// 0.01505751553351295, 0.01679337935001369, 0.015256245142156299, 0.01042830577908502, 0.003031522725559901,
// -0.0055333532968188165, -0.013403099825723372, -0.018598682349642525, -0.01944761739590459, -0.015005271935951746,
// -0.0053887880354343935, 0.008056525910253532, 0.022816244158307273, 0.035513467692208076, 0.04244131815783876,
// 0.04025481153629372, 0.02671818654865632, 0.0013810216516704976, -0.03394615682795165, -0.07502635967975885,
// -0.11540977897637611, -0.14703962203941534, -0.16119995609538576, -0.14969512896336504, -0.10610329539459686,
// -0.026921412469634916, 0.08757875030779196, 0.23293327870303457, 0.4006012210123992, 0.5786324696325503,
// 0.7528286479934068, 0.908262741447522, 1.0309661131633199, 1.1095611856548013, 1.1366197723675815,
// 1.1095611856548013, 1.0309661131633199, 0.908262741447522, 0.7528286479934068, 0.5786324696325503,
// 0.4006012210123992, 0.23293327870303457, 0.08757875030779196, -0.026921412469634916, -0.10610329539459686,
// -0.14969512896336504, -0.16119995609538576, -0.14703962203941534, -0.11540977897637611, -0.07502635967975885,
// -0.03394615682795165, 0.0013810216516704976, 0.02671818654865632, 0.04025481153629372, 0.04244131815783876,
// 0.035513467692208076, 0.022816244158307273, 0.008056525910253532, -0.0053887880354343935, -0.015005271935951746,
// -0.01944761739590459, -0.018598682349642525, -0.013403099825723372, -0.0055333532968188165, 0.003031522725559901,
// 0.01042830577908502, 0.015256245142156299, 0.01679337935001369, 0.01505751553351295, 0.01071805138282269,
// 0.004891777252042491, -0.001125978562075172, -0.006136551625729697, -0.009265784007800534, -0.010105075751866371,
// -0.008746639552588416, -0.00571615173291049, -0.0018256054303579805, 0.002017321931508163, 0.0050017573119839134,
// 0.006569574194782443, 0.006506845894531803, 0.004957956568090113, 0.002365929161655135, -0.0006430502751187517,
// -0.003403189203405097, -0.005349511529163396, -0.006126925416243605, -0.005648131453822014, -0.004092346891623224,
// -0.0018493784971116507, 0.0005756567993179152, 0.002674727068399207, 0.00404219185231544, 0.004451886520053017,
// 0.0038920145144327816, 0.002553421969211845, 0.0007766690889758685, -0.0010285696910973807, -0.0024733964729590865,
// -0.0032697038088887226, -0.0032843366522956313, -0.0025577136087664687, -0.0012851320781224025, 0.00023319405581230247,
// 0.001661182944400927, 0.002699564567597445, 0.0031468394550958484, 0.0029364388513841593, 0.0
// };
// Generated using scikit-commpy N = 150, aplha = 0.5, Ts = 1/4800 s, Fs = 48000 Hz
const std::array<float, 150> M17Demodulator::rrc_taps = std::array<float, 150>{
-8.434122e-04, +3.898184e-04, +1.628891e-03, +2.576674e-03, +2.987740e-03,
+2.729505e-03, +1.820181e-03, +4.333001e-04, -1.134215e-03, -2.525029e-03,
-3.402452e-03, -3.531573e-03, -2.841363e-03, -1.451929e-03, +3.417005e-04,
+2.128236e-03, +3.470212e-03, +4.006361e-03, +3.543024e-03, +2.112321e-03,
-1.893023e-05, -2.395144e-03, -4.465932e-03, -5.709548e-03, -5.759027e-03,
-4.501582e-03, -2.125844e-03, +8.982825e-04, +3.907892e-03, +6.188389e-03,
+7.139194e-03, +6.427125e-03, +4.090469e-03, +5.649447e-04, -3.381677e-03,
-6.799652e-03, -8.765190e-03, -8.603529e-03, -6.076811e-03, -1.489520e-03,
+4.321674e-03, +1.012385e-02, +1.453219e-02, +1.631886e-02, +1.472302e-02,
+9.691259e-03, +1.984723e-03, -6.888307e-03, -1.492227e-02, -2.001531e-02,
-2.045303e-02, -1.538011e-02, -5.154591e-03, +8.509368e-03, +2.267330e-02,
+3.359618e-02, +3.740502e-02, +3.091849e-02, +1.248579e-02, -1.731807e-02,
-5.529141e-02, -9.561492e-02, -1.303248e-01, -1.502279e-01, -1.461577e-01,
-1.104008e-01, -3.808012e-02, +7.173159e-02, +2.153664e-01, +3.845237e-01,
+5.668902e-01, +7.473693e-01, +9.097718e-01, +1.038746e+00, +1.121677e+00,
+1.150282e+00, +1.121677e+00, +1.038746e+00, +9.097718e-01, +7.473693e-01,
+5.668902e-01, +3.845237e-01, +2.153664e-01, +7.173159e-02, -3.808012e-02,
-1.104008e-01, -1.461577e-01, -1.502279e-01, -1.303248e-01, -9.561492e-02,
-5.529141e-02, -1.731807e-02, +1.248579e-02, +3.091849e-02, +3.740502e-02,
+3.359618e-02, +2.267330e-02, +8.509368e-03, -5.154591e-03, -1.538011e-02,
-2.045303e-02, -2.001531e-02, -1.492227e-02, -6.888307e-03, +1.984723e-03,
+9.691259e-03, +1.472302e-02, +1.631886e-02, +1.453219e-02, +1.012385e-02,
+4.321674e-03, -1.489520e-03, -6.076811e-03, -8.603529e-03, -8.765190e-03,
-6.799652e-03, -3.381677e-03, +5.649447e-04, +4.090469e-03, +6.427125e-03,
+7.139194e-03, +6.188389e-03, +3.907892e-03, +8.982825e-04, -2.125844e-03,
-4.501582e-03, -5.759027e-03, -5.709548e-03, -4.465932e-03, -2.395144e-03,
-1.893023e-05, +2.112321e-03, +3.543024e-03, +4.006361e-03, +3.470212e-03,
+2.128236e-03, +3.417005e-04, -1.451929e-03, -2.841363e-03, -3.531573e-03,
-3.402452e-03, -2.525029e-03, -1.134215e-03, +4.333001e-04, +1.820181e-03,
+2.729505e-03, +2.987740e-03, +2.576674e-03, +1.628891e-03, +3.898184e-04,
};
void M17Demodulator::update_values(uint8_t index)
{
correlator.apply([this,index](float t){dev.sample(t);}, index);
dev.update();
sync_sample_index = index;
}
void M17Demodulator::dcd_on()
{
// Data carrier newly detected.
dcd_ = true;
sync_count = 0;
missing_sync_count = 0;
dev.reset();
framer.reset();
decoder.reset();
}
void M17Demodulator::dcd_off()
{
// Just lost data carrier.
dcd_ = false;
demodState = DemodState::UNLOCKED;
decoder.reset();
if (diagnostic_callback)
{
diagnostic_callback(
dcd_,
dev.error(),
dev.deviation(),
dev.offset(),
(int) demodState,
(int) sync_word_type,
clock_recovery.clock_estimate(),
sample_index,
sync_sample_index,
clock_recovery.sample_index(),
-1
);
}
}
void M17Demodulator::initialize(const float input)
{
auto filtered_sample = demod_filter(input);
correlator.sample(filtered_sample);
}
void M17Demodulator::update_dcd()
{
if (!dcd_ && dcd.dcd())
{
// fputs("\nAOS\n", stderr);
dcd_on();
need_clock_reset_ = true;
}
else if (dcd_ && !dcd.dcd())
{
// fputs("\nLOS\n", stderr);
dcd_off();
}
}
void M17Demodulator::do_unlocked()
{
// We expect to find the preamble immediately after DCD.
if (missing_sync_count < 1920)
{
missing_sync_count += 1;
auto sync_index = preamble_sync(correlator);
auto sync_updated = preamble_sync.updated();
if (sync_updated)
{
sync_count = 0;
missing_sync_count = 0;
need_clock_reset_ = true;
dev.reset();
update_values(sync_index);
sample_index = sync_index;
demodState = DemodState::LSF_SYNC;
}
return;
}
auto sync_index = lsf_sync(correlator);
auto sync_updated = lsf_sync.updated();
if (sync_updated)
{
sync_count = 0;
missing_sync_count = 0;
need_clock_reset_ = true;
dev.reset();
update_values(sync_index);
sample_index = sync_index;
demodState = DemodState::FRAME;
if (sync_updated < 0) {
sync_word_type = M17FrameDecoder::SyncWordType::STREAM;
} else {
sync_word_type = M17FrameDecoder::SyncWordType::LSF;
}
return;
}
sync_index = packet_sync(correlator);
sync_updated = packet_sync.updated();
if (sync_updated < 0)
{
sync_count = 0;
missing_sync_count = 0;
need_clock_reset_ = true;
dev.reset();
update_values(sync_index);
sample_index = sync_index;
demodState = DemodState::FRAME;
sync_word_type = M17FrameDecoder::SyncWordType::BERT;
}
}
/**
* Check for LSF sync word. We only enter the DemodState::LSF_SYNC state
* if a preamble sync has been detected, which also means that sample_index
* has been initialized to a sane value for the baseband.
*/
void M17Demodulator::do_lsf_sync()
{
float sync_triggered = 0.;
float bert_triggered = 0.;
if (correlator.index() == sample_index)
{
sync_triggered = preamble_sync.triggered(correlator);
if (sync_triggered > 0.1) {
return;
}
sync_triggered = lsf_sync.triggered(correlator);
bert_triggered = packet_sync.triggered(correlator);
if (sync_triggered != 0) {
qDebug() << "modemm17::M17Demodulator::do_lsf_sync: sync_triggered:" << sync_triggered;
}
if (bert_triggered != 0) {
qDebug() << "modemm17::M17Demodulator::do_lsf_sync: bert_triggered:" << bert_triggered;
}
if (bert_triggered < 0)
{
missing_sync_count = 0;
need_clock_update_ = true;
update_values(sample_index);
demodState = DemodState::FRAME;
sync_word_type = M17FrameDecoder::SyncWordType::BERT;
qDebug() << "modemm17::M17Demodulator::do_lsf_sync: BERT:" << (int) sync_word_type;
}
else if (bert_triggered > 0)
{
missing_sync_count = 0;
need_clock_update_ = true;
update_values(sample_index);
demodState = DemodState::FRAME;
sync_word_type = M17FrameDecoder::SyncWordType::PACKET;
qDebug() << "modemm17::M17Demodulator::do_lsf_sync: PACKET:" << (int) sync_word_type;
}
else if (std::abs(sync_triggered) > 0.1)
{
missing_sync_count = 0;
need_clock_update_ = true;
update_values(sample_index);
if (sync_triggered > 0)
{
demodState = DemodState::FRAME;
sync_word_type = M17FrameDecoder::SyncWordType::LSF;
qDebug() << "modemm17::M17Demodulator::do_lsf_sync: LSF:" << (int) sync_word_type;
}
else
{
demodState = DemodState::FRAME;
sync_word_type = M17FrameDecoder::SyncWordType::STREAM;
qDebug() << "modemm17::M17Demodulator::do_lsf_sync: STREAM:" << (int) sync_word_type;
}
}
else if (++missing_sync_count > 192)
{
demodState = DemodState::UNLOCKED;
decoder.reset();
missing_sync_count = 0;
qDebug() << "modemm17::M17Demodulator::do_lsf_sync: UNLOCKED:" << (int) sync_word_type;
}
else
{
update_values(sample_index);
}
}
}
/**
* Check for a stream sync word (LSF sync word that is maximally negative).
* We can enter DemodState::STREAM_SYNC from either a valid LSF decode for
* an audio stream, or from a stream frame decode.
*
*/
void M17Demodulator::do_stream_sync()
{
uint8_t sync_index = lsf_sync(correlator);
int8_t sync_updated = lsf_sync.updated();
sync_count += 1;
if (sync_updated < 0) // Stream sync word
{
missing_sync_count = 0;
if (sync_count > 70)
{
update_values(sync_index);
sync_word_type = M17FrameDecoder::SyncWordType::STREAM;
demodState = DemodState::FRAME;
}
return;
}
else if (sync_count > 87)
{
update_values(sync_index);
missing_sync_count += 1;
if (missing_sync_count < MAX_MISSING_SYNC)
{
sync_word_type = M17FrameDecoder::SyncWordType::STREAM;
demodState = DemodState::FRAME;
}
else
{
// fputs("\n!SYNC\n", stderr);
demodState = DemodState::LSF_SYNC;
}
}
}
/**
* Check for a packet sync word. DemodState::PACKET_SYNC can only be
* entered from a valid LSF frame decode with the data/packet type bit set.
*/
void M17Demodulator::do_packet_sync()
{
auto sync_index = packet_sync(correlator);
auto sync_updated = packet_sync.updated();
sync_count += 1;
if (sync_count > 70 && sync_updated)
{
missing_sync_count = 0;
update_values(sync_index);
sync_word_type = M17FrameDecoder::SyncWordType::PACKET;
demodState = DemodState::FRAME;
}
else if (sync_count > 87)
{
missing_sync_count += 1;
if (missing_sync_count < MAX_MISSING_SYNC)
{
sync_word_type = M17FrameDecoder::SyncWordType::PACKET;
demodState = DemodState::FRAME;
}
else
{
demodState = DemodState::UNLOCKED;
decoder.reset();
}
}
}
/**
* Check for a bert sync word.
*/
void M17Demodulator::do_bert_sync()
{
auto sync_index = packet_sync(correlator);
auto sync_updated = packet_sync.updated();
sync_count += 1;
if (sync_count > 70 && sync_updated < 0)
{
missing_sync_count = 0;
update_values(sync_index);
sync_word_type = M17FrameDecoder::SyncWordType::BERT;
demodState = DemodState::FRAME;
}
else if (sync_count > 87)
{
missing_sync_count += 1;
if (missing_sync_count < MAX_MISSING_SYNC)
{
sync_word_type = M17FrameDecoder::SyncWordType::BERT;
demodState = DemodState::FRAME;
}
else
{
demodState = DemodState::UNLOCKED;
decoder.reset();
}
}
}
void M17Demodulator::do_frame(float filtered_sample)
{
if (correlator.index() != sample_index) {
return;
}
static uint8_t cost_count = 0;
auto sample = filtered_sample - dev.offset();
sample *= dev.idev();
sample *= polarity;
auto n = llr<4>(sample);
int8_t* tmp;
auto len = framer(n, &tmp);
if (len != 0)
{
need_clock_update_ = true;
M17FrameDecoder::input_buffer_t buffer;
std::copy(tmp, tmp + len, buffer.begin());
auto valid = decoder(sync_word_type, buffer, viterbi_cost);
cost_count = viterbi_cost > 90 ? cost_count + 1 : 0;
cost_count = viterbi_cost > 100 ? cost_count + 1 : cost_count;
cost_count = viterbi_cost > 110 ? cost_count + 1 : cost_count;
// qDebug() << "modemm17::M17Demodulator::do_frame: "
// << "sync_word_type:" << (int) sync_word_type
// << " len:" << len
// << " viterbi_cost: " << viterbi_cost
// << " cost_count" << cost_count;
if (cost_count > 75)
{
cost_count = 0;
demodState = DemodState::UNLOCKED;
decoder.reset();
// fputs("\nCOST\n", stderr);
return;
}
switch (decoder.state())
{
case M17FrameDecoder::State::STREAM:
demodState = DemodState::STREAM_SYNC;
break;
case M17FrameDecoder::State::LSF:
// If state == LSF, we need to recover LSF from LICH.
demodState = DemodState::STREAM_SYNC;
break;
case M17FrameDecoder::State::BERT:
demodState = DemodState::BERT_SYNC;
break;
default:
demodState = DemodState::PACKET_SYNC;
break;
}
sync_count = 0;
switch (valid)
{
case M17FrameDecoder::DecodeResult::FAIL:
break;
case M17FrameDecoder::DecodeResult::EOS:
demodState = DemodState::LSF_SYNC;
break;
case M17FrameDecoder::DecodeResult::OK:
break;
case M17FrameDecoder::DecodeResult::INCOMPLETE:
break;
case M17FrameDecoder::DecodeResult::PACKET_INCOMPLETE:
break;
}
}
}
void M17Demodulator::operator()(const float input)
{
count_++;
dcd(input);
// We need to pump a few ms of data through on startup to initialize
// the demodulator.
if (initializing_count_)
{
--initializing_count_;
initialize(input);
count_ = 0;
return;
}
if (!dcd_)
{
if (count_ % (BLOCK_SIZE * 2) == 0)
{
update_dcd();
dcd.update();
if (diagnostic_callback)
{
diagnostic_callback(
dcd_,
dev.error(),
dev.deviation(),
dev.offset(),
(int) demodState,
(int) sync_word_type,
clock_recovery.clock_estimate(),
sample_index,
sync_sample_index,
clock_recovery.sample_index(),
viterbi_cost
);
}
count_ = 0;
}
return;
}
auto filtered_sample = demod_filter(input);
correlator.sample(filtered_sample);
if (correlator.index() == 0)
{
if (need_clock_reset_)
{
clock_recovery.reset();
need_clock_reset_ = false;
}
else if (need_clock_update_) // must avoid update immediately after reset.
{
clock_recovery.update();
uint8_t clock_index = clock_recovery.sample_index();
uint8_t clock_diff = std::abs(sample_index - clock_index);
uint8_t sync_diff = std::abs(sample_index - sync_sample_index);
bool clock_diff_ok = clock_diff <= 1 || clock_diff == 9;
bool sync_diff_ok = sync_diff <= 1 || sync_diff == 9;
if (clock_diff_ok) {
sample_index = clock_index;
} else if (sync_diff_ok) {
sample_index = sync_sample_index;
}
// else unchanged.
need_clock_update_ = false;
}
}
clock_recovery(filtered_sample);
if (demodState != DemodState::UNLOCKED && correlator.index() == sample_index) {
dev.sample(filtered_sample);
}
switch (demodState)
{
case DemodState::UNLOCKED:
// In this state, the sample_index is unknown. We need to find
// a sync word to find the proper sample_index. We only leave
// this state if we believe that we have a valid sample_index.
do_unlocked();
break;
case DemodState::LSF_SYNC:
do_lsf_sync();
break;
case DemodState::STREAM_SYNC:
do_stream_sync();
break;
case DemodState::PACKET_SYNC:
do_packet_sync();
break;
case DemodState::BERT_SYNC:
do_bert_sync();
break;
case DemodState::FRAME:
do_frame(filtered_sample);
break;
}
if (count_ % (BLOCK_SIZE * 5) == 0)
{
update_dcd();
count_ = 0;
if (diagnostic_callback)
{
diagnostic_callback(
dcd_,
dev.error(),
dev.deviation(),
dev.offset(),
(int) demodState,
(int) sync_word_type,
clock_recovery.clock_estimate(),
sample_index,
sync_sample_index,
clock_recovery.sample_index(),
viterbi_cost
);
}
dcd.update();
}
}
} // modemm17
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