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Improve YSF and P25 receive BER.

This commit is contained in:
Jonathan Naylor 2017-02-12 18:44:45 +00:00
parent 1bb474dfef
commit bc6c650973
4 changed files with 192 additions and 144 deletions
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181
P25RX.cpp
View File

@ -25,7 +25,7 @@
#include "P25RX.h"
#include "Utils.h"
const q15_t SCALING_FACTOR = 18750; // Q15(0.55)
const q15_t SCALING_FACTOR = 18750; // Q15(0.57)
const uint8_t MAX_SYNC_BIT_START_ERRS = 2U;
const uint8_t MAX_SYNC_BIT_RUN_ERRS = 4U;
@ -36,6 +36,8 @@ const uint8_t BIT_MASK_TABLE[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x0
#define WRITE_BIT1(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE[(i)&7])
const uint8_t NOAVEPTR = 99U;
const uint16_t NOENDPTR = 9999U;
const unsigned int MAX_SYNC_FRAMES = 4U + 1U;
@ -58,11 +60,9 @@ m_lostCount(0U),
m_countdown(0U),
m_centre(),
m_centreVal(0),
m_centreBest(0),
m_threshold(),
m_thresholdVal(0),
m_thresholdBest(0),
m_averagePtr(0u),
m_averagePtr(NOAVEPTR),
m_rssiAccum(0U),
m_rssiCount(0U)
{
@ -74,7 +74,7 @@ void CP25RX::reset()
m_dataPtr = 0U;
m_bitPtr = 0U;
m_maxCorr = 0;
m_averagePtr = 0U;
m_averagePtr = NOAVEPTR;
m_hdrStartPtr = NOENDPTR;
m_lduStartPtr = NOENDPTR;
m_lduEndPtr = NOENDPTR;
@ -138,6 +138,8 @@ void CP25RX::processNone(q15_t sample)
io.setDecode(true);
io.setADCDetection(true);
m_averagePtr = NOAVEPTR;
m_countdown = 5U;
}
}
@ -146,15 +148,6 @@ void CP25RX::processNone(q15_t sample)
m_countdown--;
if (m_countdown == 1U) {
for (uint8_t i = 0U; i < 16U; i++) {
m_centre[i] = m_centreBest;
m_threshold[i] = m_thresholdBest;
}
m_centreVal = m_centreBest;
m_thresholdVal = m_thresholdBest;
m_averagePtr = 0U;
// These are the sync positions for the following LDU after a HDR
m_minSyncPtr = m_hdrSyncPtr + P25_HDR_FRAME_LENGTH_SAMPLES - 1U;
if (m_minSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
@ -180,34 +173,9 @@ void CP25RX::processHdr(q15_t sample)
}
if (m_dataPtr == m_maxSyncPtr) {
bool isSync = false;
if (m_minSyncPtr < m_maxSyncPtr) {
if (m_lduSyncPtr >= m_minSyncPtr && m_lduSyncPtr <= m_maxSyncPtr)
isSync = true;
} else {
if (m_lduSyncPtr >= m_minSyncPtr || m_lduSyncPtr <= m_maxSyncPtr)
isSync = true;
}
if (m_hdrSyncPtr != m_lduSyncPtr) {
calculateLevels(m_hdrStartPtr, P25_HDR_FRAME_LENGTH_SYMBOLS);
if (isSync) {
m_threshold[m_averagePtr] = m_thresholdBest;
m_centre[m_averagePtr] = m_centreBest;
m_averagePtr++;
if (m_averagePtr >= 16U)
m_averagePtr = 0U;
// Find the average centre and threshold values
m_centreVal = 0;
m_thresholdVal = 0;
for (uint8_t i = 0U; i < 16U; i++) {
m_centreVal += m_centre[i];
m_thresholdVal += m_threshold[i];
}
m_centreVal >>= 4;
m_thresholdVal >>= 4;
DEBUG4("P25RX: sync found in Hdr (best) pos/centre/threshold", m_hdrSyncPtr, m_centreBest, m_thresholdBest);
DEBUG4("P25RX: sync found in Hdr pos/centre/threshold", m_hdrSyncPtr, m_centreVal, m_thresholdVal);
uint8_t frame[P25_HDR_FRAME_LENGTH_BYTES + 1U];
@ -246,26 +214,6 @@ void CP25RX::processLdu(q15_t sample)
if (m_dataPtr == m_lduEndPtr) {
// Only update the centre and threshold if they are from a good sync
if (m_lostCount == MAX_SYNC_FRAMES) {
m_threshold[m_averagePtr] = m_thresholdBest;
m_centre[m_averagePtr] = m_centreBest;
m_averagePtr++;
if (m_averagePtr >= 16U)
m_averagePtr = 0U;
// Find the average centre and threshold values
m_centreVal = 0;
m_thresholdVal = 0;
for (uint8_t i = 0U; i < 16U; i++) {
m_centreVal += m_centre[i];
m_thresholdVal += m_threshold[i];
}
m_centreVal >>= 4;
m_thresholdVal >>= 4;
DEBUG4("P25RX: sync found in Ldu (best) pos/centre/threshold", m_lduSyncPtr, m_centreBest, m_thresholdBest);
DEBUG4("P25RX: sync found in Ldu pos/centre/threshold", m_lduSyncPtr, m_centreVal, m_thresholdVal);
m_minSyncPtr = m_lduSyncPtr + P25_LDU_FRAME_LENGTH_SAMPLES - 1U;
if (m_minSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
m_minSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
@ -275,6 +223,10 @@ void CP25RX::processLdu(q15_t sample)
m_maxSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
}
calculateLevels(m_lduStartPtr, P25_LDU_FRAME_LENGTH_SYMBOLS);
DEBUG4("P25RX: sync found in Ldu pos/centre/threshold", m_lduSyncPtr, m_centreVal, m_thresholdVal);
uint8_t frame[P25_LDU_FRAME_LENGTH_BYTES + 3U];
samplesToBits(m_lduStartPtr, P25_LDU_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
#if defined(DUMP_SAMPLES)
@ -291,9 +243,11 @@ void CP25RX::processLdu(q15_t sample)
serial.writeP25Lost();
m_state = P25RXS_NONE;
m_lduEndPtr = NOENDPTR;
m_maxCorr = 0;
m_state = P25RXS_NONE;
m_lduEndPtr = NOENDPTR;
m_averagePtr = NOAVEPTR;
m_countdown = 0U;
m_maxCorr = 0;
} else {
frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
@ -312,8 +266,8 @@ bool CP25RX::correlateSync()
ptr -= P25_LDU_FRAME_LENGTH_SAMPLES;
q31_t corr = 0;
q15_t min = 16000;
q15_t max = -16000;
q15_t min = 16000;
for (uint8_t i = 0U; i < P25_SYNC_LENGTH_SYMBOLS; i++) {
q15_t val = m_buffer[ptr];
@ -344,40 +298,38 @@ bool CP25RX::correlateSync()
}
if (corr > m_maxCorr) {
q15_t centre = (max + min) >> 1;
if (m_averagePtr == NOAVEPTR) {
m_centreVal = (max + min) >> 1;
q31_t v1 = (max - centre) * SCALING_FACTOR;
q15_t threshold = q15_t(v1 >> 15);
uint8_t sync[P25_SYNC_BYTES_LENGTH];
q31_t v1 = (max - m_centreVal) * SCALING_FACTOR;
m_thresholdVal = q15_t(v1 >> 15);
}
uint16_t startPtr = m_dataPtr + P25_LDU_FRAME_LENGTH_SAMPLES - P25_SYNC_LENGTH_SAMPLES + P25_RADIO_SYMBOL_LENGTH;
if (startPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
startPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
uint8_t sync[P25_SYNC_BYTES_LENGTH];
samplesToBits(startPtr, P25_SYNC_LENGTH_SYMBOLS, sync, 0U, m_centreVal, m_thresholdVal);
uint8_t maxErrs;
if (m_state == P25RXS_NONE) {
samplesToBits(startPtr, P25_SYNC_LENGTH_SYMBOLS, sync, 0U, centre, threshold);
if (m_state == P25RXS_NONE)
maxErrs = MAX_SYNC_BIT_START_ERRS;
} else {
samplesToBits(startPtr, P25_SYNC_LENGTH_SYMBOLS, sync, 0U, m_centreVal, m_thresholdVal);
else
maxErrs = MAX_SYNC_BIT_RUN_ERRS;
}
uint8_t errs = 0U;
for (uint8_t i = 0U; i < P25_SYNC_BYTES_LENGTH; i++)
errs += countBits8(sync[i] ^ P25_SYNC_BYTES[i]);
if (errs <= maxErrs) {
m_maxCorr = corr;
m_thresholdBest = threshold;
m_centreBest = centre;
m_lostCount = MAX_SYNC_FRAMES;
m_maxCorr = corr;
m_lostCount = MAX_SYNC_FRAMES;
m_lduSyncPtr = m_dataPtr;
m_lduSyncPtr = m_dataPtr;
// These are the positions of the start and end of an LDU
m_lduStartPtr = startPtr;
m_lduStartPtr = startPtr;
m_lduEndPtr = m_dataPtr + P25_LDU_FRAME_LENGTH_SAMPLES - P25_SYNC_LENGTH_SAMPLES - 1U;
if (m_lduEndPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
@ -407,6 +359,70 @@ bool CP25RX::correlateSync()
return false;
}
void CP25RX::calculateLevels(uint16_t start, uint16_t count)
{
q15_t maxPos = -16000;
q15_t minPos = 16000;
q15_t maxNeg = 16000;
q15_t minNeg = -16000;
for (uint16_t i = 0U; i < count; i++) {
q15_t sample = m_buffer[start];
if (sample > 0) {
if (sample > maxPos)
maxPos = sample;
if (sample < minPos)
minPos = sample;
} else {
if (sample < maxNeg)
maxNeg = sample;
if (sample > minNeg)
minNeg = sample;
}
start += P25_RADIO_SYMBOL_LENGTH;
if (start >= P25_LDU_FRAME_LENGTH_SAMPLES)
start -= P25_LDU_FRAME_LENGTH_SAMPLES;
}
q15_t posThresh = (maxPos + minPos) >> 1;
q15_t negThresh = (maxNeg + minNeg) >> 1;
q15_t centre = (posThresh + negThresh) >> 1;
q15_t threshold = posThresh - centre;
DEBUG5("P25RX: pos/neg/centre/threshold", posThresh, negThresh, centre, threshold);
if (m_averagePtr == NOAVEPTR) {
for (uint8_t i = 0U; i < 16U; i++) {
m_centre[i] = centre;
m_threshold[i] = threshold;
}
m_averagePtr = 0U;
} else {
m_centre[m_averagePtr] = centre;
m_threshold[m_averagePtr] = threshold;
m_averagePtr++;
if (m_averagePtr >= 16U)
m_averagePtr = 0U;
}
m_centreVal = 0;
m_thresholdVal = 0;
for (uint8_t i = 0U; i < 16U; i++) {
m_centreVal += m_centre[i];
m_thresholdVal += m_threshold[i];
}
m_centreVal >>= 4;
m_thresholdVal >>= 4;
}
void CP25RX::samplesToBits(uint16_t start, uint16_t count, uint8_t* buffer, uint16_t offset, q15_t centre, q15_t threshold)
{
for (uint16_t i = 0U; i < count; i++) {
@ -467,9 +483,6 @@ void CP25RX::writeSync(uint16_t start)
q15_t sync[P25_SYNC_LENGTH_SYMBOLS];
for (uint16_t i = 0U; i < P25_SYNC_LENGTH_SYMBOLS; i++) {
if (i == (P25_SYNC_LENGTH_SYMBOLS - 1U))
DEBUG4("P25RX: sync1/sync2/start", m_hdrSyncPtr, m_lduSyncPtr, start);
sync[i] = m_buffer[start];
start += P25_RADIO_SYMBOL_LENGTH;

3
P25RX.h
View File

@ -54,10 +54,8 @@ private:
uint8_t m_countdown;
q15_t m_centre[16U];
q15_t m_centreVal;
q15_t m_centreBest;
q15_t m_threshold[16U];
q15_t m_thresholdVal;
q15_t m_thresholdBest;
uint8_t m_averagePtr;
uint32_t m_rssiAccum;
uint16_t m_rssiCount;
@ -66,6 +64,7 @@ private:
void processHdr(q15_t sample);
void processLdu(q15_t sample);
bool correlateSync();
void calculateLevels(uint16_t start, uint16_t count);
void samplesToBits(uint16_t start, uint16_t count, uint8_t* buffer, uint16_t offset, q15_t centre, q15_t threshold);
void writeRSSILdu(uint8_t* ldu);
void writeSync(uint16_t start);

149
YSFRX.cpp
View File

@ -36,6 +36,8 @@ const uint8_t BIT_MASK_TABLE[] = {0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02
#define WRITE_BIT1(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE[(i)&7])
const uint8_t NOAVEPTR = 99U;
const uint16_t NOENDPTR = 9999U;
const unsigned int MAX_SYNC_FRAMES = 4U + 1U;
@ -56,11 +58,9 @@ m_lostCount(0U),
m_countdown(0U),
m_centre(),
m_centreVal(0),
m_centreBest(0),
m_threshold(),
m_thresholdVal(0),
m_thresholdBest(0),
m_averagePtr(0u),
m_averagePtr(NOAVEPTR),
m_rssiAccum(0U),
m_rssiCount(0U)
{
@ -72,7 +72,7 @@ void CYSFRX::reset()
m_dataPtr = 0U;
m_bitPtr = 0U;
m_maxCorr = 0;
m_averagePtr = 0U;
m_averagePtr = NOAVEPTR;
m_startPtr = NOENDPTR;
m_endPtr = NOENDPTR;
m_syncPtr = NOENDPTR;
@ -131,6 +131,8 @@ void CYSFRX::processNone(q15_t sample)
io.setDecode(true);
io.setADCDetection(true);
m_averagePtr = NOAVEPTR;
m_countdown = 5U;
}
}
@ -139,15 +141,6 @@ void CYSFRX::processNone(q15_t sample)
m_countdown--;
if (m_countdown == 1U) {
for (uint8_t i = 0U; i < 16U; i++) {
m_centre[i] = m_centreBest;
m_threshold[i] = m_thresholdBest;
}
m_centreVal = m_centreBest;
m_thresholdVal = m_thresholdBest;
m_averagePtr = 0U;
m_minSyncPtr = m_syncPtr + YSF_FRAME_LENGTH_SAMPLES - 1U;
if (m_minSyncPtr >= YSF_FRAME_LENGTH_SAMPLES)
m_minSyncPtr -= YSF_FRAME_LENGTH_SAMPLES;
@ -174,26 +167,6 @@ void CYSFRX::processData(q15_t sample)
if (m_dataPtr == m_endPtr) {
// Only update the centre and threshold if they are from a good sync
if (m_lostCount == MAX_SYNC_FRAMES) {
m_threshold[m_averagePtr] = m_thresholdBest;
m_centre[m_averagePtr] = m_centreBest;
m_averagePtr++;
if (m_averagePtr >= 16U)
m_averagePtr = 0U;
// Find the average centre and threshold values
m_centreVal = 0;
m_thresholdVal = 0;
for (uint8_t i = 0U; i < 16U; i++) {
m_centreVal += m_centre[i];
m_thresholdVal += m_threshold[i];
}
m_centreVal >>= 4;
m_thresholdVal >>= 4;
DEBUG4("YSFRX: sync found (best) pos/centre/threshold", m_syncPtr, m_centreBest, m_thresholdBest);
DEBUG4("YSFRX: sync found pos/centre/threshold", m_syncPtr, m_centreVal, m_thresholdVal);
m_minSyncPtr = m_syncPtr + YSF_FRAME_LENGTH_SAMPLES - 1U;
if (m_minSyncPtr >= YSF_FRAME_LENGTH_SAMPLES)
m_minSyncPtr -= YSF_FRAME_LENGTH_SAMPLES;
@ -203,6 +176,10 @@ void CYSFRX::processData(q15_t sample)
m_maxSyncPtr -= YSF_FRAME_LENGTH_SAMPLES;
}
calculateLevels(m_startPtr, YSF_FRAME_LENGTH_SYMBOLS);
DEBUG4("YSFRX: sync found pos/centre/threshold", m_syncPtr, m_centreVal, m_thresholdVal);
uint8_t frame[YSF_FRAME_LENGTH_BYTES + 3U];
samplesToBits(m_startPtr, YSF_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
#if defined(DUMP_SAMPLES)
@ -219,10 +196,11 @@ void CYSFRX::processData(q15_t sample)
serial.writeYSFLost();
m_state = YSFRXS_NONE;
m_endPtr = NOENDPTR;
m_countdown = 0U;
m_maxCorr = 0;
m_state = YSFRXS_NONE;
m_endPtr = NOENDPTR;
m_averagePtr = NOAVEPTR;
m_countdown = 0U;
m_maxCorr = 0;
} else {
frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
@ -241,8 +219,8 @@ bool CYSFRX::correlateSync()
ptr -= YSF_FRAME_LENGTH_SAMPLES;
q31_t corr = 0;
q15_t min = 16000;
q15_t max = -16000;
q15_t min = 16000;
for (uint8_t i = 0U; i < YSF_SYNC_LENGTH_SYMBOLS; i++) {
q15_t val = m_buffer[ptr];
@ -273,36 +251,34 @@ bool CYSFRX::correlateSync()
}
if (corr > m_maxCorr) {
q15_t centre = (max + min) >> 1;
if (m_averagePtr == NOAVEPTR) {
m_centreVal = (max + min) >> 1;
q31_t v1 = (max - centre) * SCALING_FACTOR;
q15_t threshold = q15_t(v1 >> 15);
uint8_t sync[YSF_SYNC_BYTES_LENGTH];
q31_t v1 = (max - m_centreVal) * SCALING_FACTOR;
m_thresholdVal = q15_t(v1 >> 15);
}
uint16_t startPtr = m_dataPtr + YSF_FRAME_LENGTH_SAMPLES - YSF_SYNC_LENGTH_SAMPLES + YSF_RADIO_SYMBOL_LENGTH;
if (startPtr >= YSF_FRAME_LENGTH_SAMPLES)
startPtr -= YSF_FRAME_LENGTH_SAMPLES;
uint8_t sync[YSF_SYNC_BYTES_LENGTH];
samplesToBits(startPtr, YSF_SYNC_LENGTH_SYMBOLS, sync, 0U, m_centreVal, m_thresholdVal);
uint8_t maxErrs;
if (m_state == YSFRXS_NONE) {
samplesToBits(startPtr, YSF_SYNC_LENGTH_SYMBOLS, sync, 0U, centre, threshold);
if (m_state == YSFRXS_NONE)
maxErrs = MAX_SYNC_BIT_START_ERRS;
} else {
samplesToBits(startPtr, YSF_SYNC_LENGTH_SYMBOLS, sync, 0U, m_centreVal, m_thresholdVal);
else
maxErrs = MAX_SYNC_BIT_RUN_ERRS;
}
uint8_t errs = 0U;
for (uint8_t i = 0U; i < YSF_SYNC_BYTES_LENGTH; i++)
errs += countBits8(sync[i] ^ YSF_SYNC_BYTES[i]);
if (errs <= maxErrs) {
m_maxCorr = corr;
m_thresholdBest = threshold;
m_centreBest = centre;
m_lostCount = MAX_SYNC_FRAMES;
m_syncPtr = m_dataPtr;
m_maxCorr = corr;
m_lostCount = MAX_SYNC_FRAMES;
m_syncPtr = m_dataPtr;
m_startPtr = startPtr;
@ -318,6 +294,70 @@ bool CYSFRX::correlateSync()
return false;
}
void CYSFRX::calculateLevels(uint16_t start, uint16_t count)
{
q15_t maxPos = -16000;
q15_t minPos = 16000;
q15_t maxNeg = 16000;
q15_t minNeg = -16000;
for (uint16_t i = 0U; i < count; i++) {
q15_t sample = m_buffer[start];
if (sample > 0) {
if (sample > maxPos)
maxPos = sample;
if (sample < minPos)
minPos = sample;
} else {
if (sample < maxNeg)
maxNeg = sample;
if (sample > minNeg)
minNeg = sample;
}
start += YSF_RADIO_SYMBOL_LENGTH;
if (start >= YSF_FRAME_LENGTH_SAMPLES)
start -= YSF_FRAME_LENGTH_SAMPLES;
}
q15_t posThresh = (maxPos + minPos) >> 1;
q15_t negThresh = (maxNeg + minNeg) >> 1;
q15_t centre = (posThresh + negThresh) >> 1;
q15_t threshold = posThresh - centre;
DEBUG5("YSFRX: pos/neg/centre/threshold", posThresh, negThresh, centre, threshold);
if (m_averagePtr == NOAVEPTR) {
for (uint8_t i = 0U; i < 16U; i++) {
m_centre[i] = centre;
m_threshold[i] = threshold;
}
m_averagePtr = 0U;
} else {
m_centre[m_averagePtr] = centre;
m_threshold[m_averagePtr] = threshold;
m_averagePtr++;
if (m_averagePtr >= 16U)
m_averagePtr = 0U;
}
m_centreVal = 0;
m_thresholdVal = 0;
for (uint8_t i = 0U; i < 16U; i++) {
m_centreVal += m_centre[i];
m_thresholdVal += m_threshold[i];
}
m_centreVal >>= 4;
m_thresholdVal >>= 4;
}
void CYSFRX::samplesToBits(uint16_t start, uint16_t count, uint8_t* buffer, uint16_t offset, q15_t centre, q15_t threshold)
{
for (uint16_t i = 0U; i < count; i++) {
@ -378,9 +418,6 @@ void CYSFRX::writeSync(uint16_t start)
q15_t sync[YSF_SYNC_LENGTH_SYMBOLS];
for (uint16_t i = 0U; i < YSF_SYNC_LENGTH_SYMBOLS; i++) {
if (i == (YSF_SYNC_LENGTH_SYMBOLS - 1U))
DEBUG3("YSFRX: sync/start", m_syncPtr, start);
sync[i] = m_buffer[start];
start += YSF_RADIO_SYMBOL_LENGTH;

3
YSFRX.h
View File

@ -51,10 +51,8 @@ private:
uint8_t m_countdown;
q15_t m_centre[16U];
q15_t m_centreVal;
q15_t m_centreBest;
q15_t m_threshold[16U];
q15_t m_thresholdVal;
q15_t m_thresholdBest;
uint8_t m_averagePtr;
uint32_t m_rssiAccum;
uint16_t m_rssiCount;
@ -62,6 +60,7 @@ private:
void processNone(q15_t sample);
void processData(q15_t sample);
bool correlateSync();
void calculateLevels(uint16_t start, uint16_t count);
void samplesToBits(uint16_t start, uint16_t count, uint8_t* buffer, uint16_t offset, q15_t centre, q15_t threshold);
void writeRSSIData(uint8_t* data);
void writeSync(uint16_t start);