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Use the BER from the Viterbi decoder in M17 mode to determine if the

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audio is usable or not.
This commit is contained in:
Jonathan Naylor 2021-06-28 19:16:16 +01:00
parent f7b8448963
commit dae05ad58a
4 changed files with 72 additions and 58 deletions
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119
M17Control.cpp
View file

@ -79,6 +79,7 @@ m_rfErrs(0U),
m_rfBits(1U),
m_rfLSF(),
m_rfLSFn(0U),
m_rfFN(0U),
m_netLSF(),
m_netLSFn(0U),
m_rssiMapper(rssiMapper),
@ -172,7 +173,7 @@ bool CM17Control::writeModem(unsigned char* data, unsigned int len)
CM17Convolution conv;
unsigned char frame[M17_LSF_LENGTH_BYTES];
conv.decodeLinkSetup(data + 2U + M17_SYNC_LENGTH_BYTES, frame);
unsigned int ber = conv.decodeLinkSetup(data + 2U + M17_SYNC_LENGTH_BYTES, frame);
bool valid = CM17CRC::checkCRC16(frame, M17_LSF_LENGTH_BYTES);
if (valid) {
@ -184,15 +185,16 @@ bool CM17Control::writeModem(unsigned char* data, unsigned int len)
return false;
}
m_rfFrames = 0U;
m_rfErrs = 0U;
m_rfBits = 1U;
m_rfFrames = 0U;
m_rfErrs = ber;
m_rfBits = 368U;
m_rfTimeoutTimer.start();
m_minRSSI = m_rssi;
m_maxRSSI = m_rssi;
m_aveRSSI = m_rssi;
m_minRSSI = m_rssi;
m_maxRSSI = m_rssi;
m_aveRSSI = m_rssi;
m_rssiCount = 1U;
m_rfLSFn = 0U;
m_rfFN = 0U;
#if defined(DUMP_M17)
openFile();
@ -233,14 +235,15 @@ bool CM17Control::writeModem(unsigned char* data, unsigned int len)
return false;
}
m_rfFrames = 0U;
m_rfErrs = 0U;
m_rfBits = 1U;
m_rfFrames = 0U;
m_rfErrs = 0U;
m_rfBits = 1U;
m_rfTimeoutTimer.start();
m_minRSSI = m_rssi;
m_maxRSSI = m_rssi;
m_aveRSSI = m_rssi;
m_minRSSI = m_rssi;
m_maxRSSI = m_rssi;
m_aveRSSI = m_rssi;
m_rssiCount = 1U;
m_rfFN = 0U;
#if defined(DUMP_M17)
openFile();
@ -257,59 +260,64 @@ bool CM17Control::writeModem(unsigned char* data, unsigned int len)
#endif
CM17Convolution conv;
unsigned char frame[M17_FN_LENGTH_BYTES + M17_PAYLOAD_LENGTH_BYTES];
unsigned int convBER = conv.decodeData(data + 2U + M17_SYNC_LENGTH_BYTES + M17_LICH_FRAGMENT_FEC_LENGTH_BYTES, frame);
unsigned int errors = conv.decodeData(data + 2U + M17_SYNC_LENGTH_BYTES + M17_LICH_FRAGMENT_FEC_LENGTH_BYTES, frame);
unsigned int fn = ((frame[0U] << 8) + (frame[1U] << 0)) & 0x7FU;
// If we have a BER of less than 12, then we consider the audio to be usable
bool valid = errors < 12U;
unsigned char rfData[2U + M17_FRAME_LENGTH_BYTES];
if (!valid) {
frame[0U] = (m_rfFN >> 8) & 0xFFU;
frame[1U] = (m_rfFN >> 0) & 0xFFU;
rfData[0U] = TAG_DATA1;
rfData[1U] = 0x00U;
// Generate the sync
CSync::addM17StreamSync(rfData + 2U);
unsigned char lich[M17_LICH_FRAGMENT_LENGTH_BYTES];
m_rfLSF.getFragment(lich, m_rfLSFn);
// Add the fragment number
lich[5U] = (m_rfLSFn & 0x07U) << 5;
unsigned int frag1, frag2, frag3, frag4;
CM17Utils::splitFragmentLICH(lich, frag1, frag2, frag3, frag4);
// Add Golay to the LICH fragment here
unsigned int lich1 = CGolay24128::encode24128(frag1);
unsigned int lich2 = CGolay24128::encode24128(frag2);
unsigned int lich3 = CGolay24128::encode24128(frag3);
unsigned int lich4 = CGolay24128::encode24128(frag4);
CM17Utils::combineFragmentLICHFEC(lich1, lich2, lich3, lich4, rfData + 2U + M17_SYNC_LENGTH_BYTES);
// Add the Convolution FEC
conv.encodeData(frame, rfData + 2U + M17_SYNC_LENGTH_BYTES + M17_LICH_FRAGMENT_FEC_LENGTH_BYTES);
// Calculate the BER
unsigned int errors = 0U;
for (unsigned int i = 0U; i < (M17_FN_LENGTH_BYTES + M17_PAYLOAD_LENGTH_BYTES); i++) {
unsigned int offset = i + 2U + M17_SYNC_LENGTH_BYTES + M17_LICH_FRAGMENT_FEC_LENGTH_BYTES;
errors += CUtils::countBits(rfData[offset] ^ data[offset]);
::memcpy(frame + 2U + 0U, M17_3200_SILENCE, 8U);
::memcpy(frame + 2U + 8U, M17_3200_SILENCE, 8U);
} else {
m_rfFN = ((frame[0U] << 8) + (frame[1U] << 0)) & 0x7FU;
}
LogDebug("M17, FN: %u, errs: %u/%u/144 (%.1f%%)", fn & 0x7FU, errors, convBER, float(errors) / 1.44F);
LogDebug("M17, FN: %u, errs: %u/272 (%.1f%%)", m_rfFN & 0x7FU, errors, float(errors) / 2.72F);
m_rfBits += M17_FN_LENGTH_BITS + M17_PAYLOAD_LENGTH_BITS;
m_rfBits += 272U;
m_rfErrs += errors;
float ber = float(m_rfErrs) / float(m_rfBits);
m_display->writeM17BER(ber);
unsigned char temp[M17_FRAME_LENGTH_BYTES];
interleaver(rfData + 2U, temp);
decorrelator(temp, rfData + 2U);
if (m_duplex) {
unsigned char rfData[2U + M17_FRAME_LENGTH_BYTES];
rfData[0U] = TAG_DATA1;
rfData[1U] = 0x00U;
// Generate the sync
CSync::addM17StreamSync(rfData + 2U);
unsigned char lich[M17_LICH_FRAGMENT_LENGTH_BYTES];
m_rfLSF.getFragment(lich, m_rfLSFn);
// Add the fragment number
lich[5U] = (m_rfLSFn & 0x07U) << 5;
unsigned int frag1, frag2, frag3, frag4;
CM17Utils::splitFragmentLICH(lich, frag1, frag2, frag3, frag4);
// Add Golay to the LICH fragment here
unsigned int lich1 = CGolay24128::encode24128(frag1);
unsigned int lich2 = CGolay24128::encode24128(frag2);
unsigned int lich3 = CGolay24128::encode24128(frag3);
unsigned int lich4 = CGolay24128::encode24128(frag4);
CM17Utils::combineFragmentLICHFEC(lich1, lich2, lich3, lich4, rfData + 2U + M17_SYNC_LENGTH_BYTES);
// Add the Convolution FEC
conv.encodeData(frame, rfData + 2U + M17_SYNC_LENGTH_BYTES + M17_LICH_FRAGMENT_FEC_LENGTH_BYTES);
unsigned char temp[M17_FRAME_LENGTH_BYTES];
interleaver(rfData + 2U, temp);
decorrelator(temp, rfData + 2U);
if (m_duplex)
writeQueueRF(rfData);
}
if (m_network != NULL && m_rfTimeoutTimer.isRunning() && !m_rfTimeoutTimer.hasExpired()) {
unsigned char netData[M17_LSF_LENGTH_BYTES + M17_FN_LENGTH_BYTES + M17_PAYLOAD_LENGTH_BYTES + M17_CRC_LENGTH_BYTES];
@ -325,13 +333,14 @@ bool CM17Control::writeModem(unsigned char* data, unsigned int len)
}
m_rfFrames++;
m_rfFN++;
m_rfLSFn++;
if (m_rfLSFn >= 6U)
m_rfLSFn = 0U;
// Only check for the EOT marker if the frame has a valid CRC
if ((fn & 0x8000U) == 0x8000U) {
// Only check for the EOT marker if the frame has a reasonable BER
if (valid && (m_rfFN & 0x8000U) == 0x8000U) {
std::string source = m_rfLSF.getSource();
std::string dest = m_rfLSF.getDest();

1
M17Control.h
View file

@ -69,6 +69,7 @@ private:
unsigned int m_rfBits;
CM17LSF m_rfLSF;
unsigned int m_rfLSFn;
unsigned int m_rfFN;
CM17LSF m_netLSF;
unsigned int m_netLSFn;
CRSSIInterpolator* m_rssiMapper;

8
M17Convolution.cpp
View file

@ -23,6 +23,8 @@
#include <cstring>
#include <cstdlib>
const unsigned int PUNCTURE_LIST_LINK_SETUP_COUNT = 60U;
const unsigned int PUNCTURE_LIST_LINK_SETUP[] = {
3U, 6U, 9U, 12U, 19U, 22U, 25U, 28U, 35U, 38U, 41U, 44U, 51U, 54U, 57U, 64U, 67U, 70U, 73U, 80U, 83U, 86U, 89U, 96U, 99U, 102U,
105U, 112U, 115U, 118U, 125U, 128U, 131U, 134U, 141U, 144U, 147U, 150U, 157U, 160U, 163U, 166U, 173U, 176U, 179U, 186U, 189U,
@ -31,6 +33,8 @@ const unsigned int PUNCTURE_LIST_LINK_SETUP[] = {
362U, 369U, 372U, 375U, 378U, 385U, 388U, 391U, 394U, 401U, 404U, 407U, 410U, 417U, 420U, 423U, 430U, 433U, 436U, 439U, 446U,
449U, 452U, 455U, 462U, 465U, 468U, 471U, 478U, 481U, 484U};
const unsigned int PUNCTURE_LIST_DATA_COUNT = 22U;
const unsigned int PUNCTURE_LIST_DATA[] = {
11U, 23U, 35U, 47U, 59U, 71U, 83U, 95U, 107U, 119U, 131U, 143U, 155U, 167U, 179U, 191U, 203U, 215U, 227U, 239U, 251U, 263U,
275U, 287U, 299U, 311U, 323U };
@ -150,7 +154,7 @@ unsigned int CM17Convolution::decodeLinkSetup(const unsigned char* in, unsigned
decode(s0, s1);
}
return chainback(out, 240U);
return chainback(out, 240U) - PUNCTURE_LIST_LINK_SETUP_COUNT;
}
unsigned int CM17Convolution::decodeData(const unsigned char* in, unsigned char* out)
@ -185,7 +189,7 @@ unsigned int CM17Convolution::decodeData(const unsigned char* in, unsigned char*
decode(s0, s1);
}
return chainback(out, 160U);
return chainback(out, 160U) - PUNCTURE_LIST_DATA_COUNT;
}
void CM17Convolution::start()

2
Version.h
View file

@ -19,6 +19,6 @@
#if !defined(VERSION_H)
#define VERSION_H
const char* VERSION = "20210627";
const char* VERSION = "20210628";
#endif