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Improve YSF and P25 receive BER.
This commit is contained in:
Jonathan Naylor
parent
1bb474dfef
commit
bc6c650973
4 changed files with 192 additions and 144 deletions
181
P25RX.cpp
181
P25RX.cpp
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@ -25,7 +25,7 @@
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#include "P25RX.h"
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#include "Utils.h"
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const q15_t SCALING_FACTOR = 18750; // Q15(0.55)
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const q15_t SCALING_FACTOR = 18750; // Q15(0.57)
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const uint8_t MAX_SYNC_BIT_START_ERRS = 2U;
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const uint8_t MAX_SYNC_BIT_RUN_ERRS = 4U;
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@ -36,6 +36,8 @@ const uint8_t BIT_MASK_TABLE[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x0
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#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])
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const uint8_t NOAVEPTR = 99U;
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const uint16_t NOENDPTR = 9999U;
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const unsigned int MAX_SYNC_FRAMES = 4U + 1U;
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@ -58,11 +60,9 @@ m_lostCount(0U),
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m_countdown(0U),
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m_centre(),
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m_centreVal(0),
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m_centreBest(0),
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m_threshold(),
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m_thresholdVal(0),
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m_thresholdBest(0),
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m_averagePtr(0u),
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m_averagePtr(NOAVEPTR),
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m_rssiAccum(0U),
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m_rssiCount(0U)
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{
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@ -74,7 +74,7 @@ void CP25RX::reset()
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m_dataPtr = 0U;
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m_bitPtr = 0U;
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m_maxCorr = 0;
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m_averagePtr = 0U;
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m_averagePtr = NOAVEPTR;
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m_hdrStartPtr = NOENDPTR;
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m_lduStartPtr = NOENDPTR;
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m_lduEndPtr = NOENDPTR;
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@ -138,6 +138,8 @@ void CP25RX::processNone(q15_t sample)
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io.setDecode(true);
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io.setADCDetection(true);
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m_averagePtr = NOAVEPTR;
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m_countdown = 5U;
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}
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}
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@ -146,15 +148,6 @@ void CP25RX::processNone(q15_t sample)
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m_countdown--;
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if (m_countdown == 1U) {
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for (uint8_t i = 0U; i < 16U; i++) {
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m_centre[i] = m_centreBest;
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m_threshold[i] = m_thresholdBest;
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}
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m_centreVal = m_centreBest;
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m_thresholdVal = m_thresholdBest;
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m_averagePtr = 0U;
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// These are the sync positions for the following LDU after a HDR
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m_minSyncPtr = m_hdrSyncPtr + P25_HDR_FRAME_LENGTH_SAMPLES - 1U;
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if (m_minSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
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@ -180,34 +173,9 @@ void CP25RX::processHdr(q15_t sample)
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}
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if (m_dataPtr == m_maxSyncPtr) {
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bool isSync = false;
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if (m_minSyncPtr < m_maxSyncPtr) {
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if (m_lduSyncPtr >= m_minSyncPtr && m_lduSyncPtr <= m_maxSyncPtr)
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isSync = true;
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} else {
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if (m_lduSyncPtr >= m_minSyncPtr || m_lduSyncPtr <= m_maxSyncPtr)
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isSync = true;
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}
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if (m_hdrSyncPtr != m_lduSyncPtr) {
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calculateLevels(m_hdrStartPtr, P25_HDR_FRAME_LENGTH_SYMBOLS);
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if (isSync) {
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m_threshold[m_averagePtr] = m_thresholdBest;
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m_centre[m_averagePtr] = m_centreBest;
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m_averagePtr++;
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if (m_averagePtr >= 16U)
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m_averagePtr = 0U;
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// Find the average centre and threshold values
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m_centreVal = 0;
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m_thresholdVal = 0;
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for (uint8_t i = 0U; i < 16U; i++) {
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m_centreVal += m_centre[i];
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m_thresholdVal += m_threshold[i];
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}
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m_centreVal >>= 4;
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m_thresholdVal >>= 4;
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DEBUG4("P25RX: sync found in Hdr (best) pos/centre/threshold", m_hdrSyncPtr, m_centreBest, m_thresholdBest);
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DEBUG4("P25RX: sync found in Hdr pos/centre/threshold", m_hdrSyncPtr, m_centreVal, m_thresholdVal);
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uint8_t frame[P25_HDR_FRAME_LENGTH_BYTES + 1U];
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@ -246,26 +214,6 @@ void CP25RX::processLdu(q15_t sample)
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if (m_dataPtr == m_lduEndPtr) {
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// Only update the centre and threshold if they are from a good sync
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if (m_lostCount == MAX_SYNC_FRAMES) {
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m_threshold[m_averagePtr] = m_thresholdBest;
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m_centre[m_averagePtr] = m_centreBest;
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m_averagePtr++;
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if (m_averagePtr >= 16U)
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m_averagePtr = 0U;
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// Find the average centre and threshold values
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m_centreVal = 0;
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m_thresholdVal = 0;
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for (uint8_t i = 0U; i < 16U; i++) {
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m_centreVal += m_centre[i];
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m_thresholdVal += m_threshold[i];
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}
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m_centreVal >>= 4;
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m_thresholdVal >>= 4;
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DEBUG4("P25RX: sync found in Ldu (best) pos/centre/threshold", m_lduSyncPtr, m_centreBest, m_thresholdBest);
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DEBUG4("P25RX: sync found in Ldu pos/centre/threshold", m_lduSyncPtr, m_centreVal, m_thresholdVal);
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m_minSyncPtr = m_lduSyncPtr + P25_LDU_FRAME_LENGTH_SAMPLES - 1U;
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if (m_minSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
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m_minSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
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@ -275,6 +223,10 @@ void CP25RX::processLdu(q15_t sample)
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m_maxSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
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}
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calculateLevels(m_lduStartPtr, P25_LDU_FRAME_LENGTH_SYMBOLS);
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DEBUG4("P25RX: sync found in Ldu pos/centre/threshold", m_lduSyncPtr, m_centreVal, m_thresholdVal);
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uint8_t frame[P25_LDU_FRAME_LENGTH_BYTES + 3U];
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samplesToBits(m_lduStartPtr, P25_LDU_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
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#if defined(DUMP_SAMPLES)
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@ -291,9 +243,11 @@ void CP25RX::processLdu(q15_t sample)
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serial.writeP25Lost();
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m_state = P25RXS_NONE;
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m_lduEndPtr = NOENDPTR;
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m_maxCorr = 0;
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m_state = P25RXS_NONE;
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m_lduEndPtr = NOENDPTR;
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m_averagePtr = NOAVEPTR;
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m_countdown = 0U;
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m_maxCorr = 0;
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} else {
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frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
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@ -312,8 +266,8 @@ bool CP25RX::correlateSync()
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ptr -= P25_LDU_FRAME_LENGTH_SAMPLES;
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q31_t corr = 0;
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q15_t min = 16000;
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q15_t max = -16000;
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q15_t min = 16000;
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for (uint8_t i = 0U; i < P25_SYNC_LENGTH_SYMBOLS; i++) {
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q15_t val = m_buffer[ptr];
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@ -344,40 +298,38 @@ bool CP25RX::correlateSync()
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}
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if (corr > m_maxCorr) {
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q15_t centre = (max + min) >> 1;
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if (m_averagePtr == NOAVEPTR) {
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m_centreVal = (max + min) >> 1;
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q31_t v1 = (max - centre) * SCALING_FACTOR;
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q15_t threshold = q15_t(v1 >> 15);
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uint8_t sync[P25_SYNC_BYTES_LENGTH];
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q31_t v1 = (max - m_centreVal) * SCALING_FACTOR;
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m_thresholdVal = q15_t(v1 >> 15);
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}
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uint16_t startPtr = m_dataPtr + P25_LDU_FRAME_LENGTH_SAMPLES - P25_SYNC_LENGTH_SAMPLES + P25_RADIO_SYMBOL_LENGTH;
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if (startPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
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startPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
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uint8_t sync[P25_SYNC_BYTES_LENGTH];
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samplesToBits(startPtr, P25_SYNC_LENGTH_SYMBOLS, sync, 0U, m_centreVal, m_thresholdVal);
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uint8_t maxErrs;
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if (m_state == P25RXS_NONE) {
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samplesToBits(startPtr, P25_SYNC_LENGTH_SYMBOLS, sync, 0U, centre, threshold);
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if (m_state == P25RXS_NONE)
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maxErrs = MAX_SYNC_BIT_START_ERRS;
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} else {
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samplesToBits(startPtr, P25_SYNC_LENGTH_SYMBOLS, sync, 0U, m_centreVal, m_thresholdVal);
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else
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maxErrs = MAX_SYNC_BIT_RUN_ERRS;
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}
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uint8_t errs = 0U;
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for (uint8_t i = 0U; i < P25_SYNC_BYTES_LENGTH; i++)
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errs += countBits8(sync[i] ^ P25_SYNC_BYTES[i]);
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if (errs <= maxErrs) {
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m_maxCorr = corr;
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m_thresholdBest = threshold;
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m_centreBest = centre;
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m_lostCount = MAX_SYNC_FRAMES;
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m_maxCorr = corr;
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m_lostCount = MAX_SYNC_FRAMES;
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m_lduSyncPtr = m_dataPtr;
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m_lduSyncPtr = m_dataPtr;
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// These are the positions of the start and end of an LDU
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m_lduStartPtr = startPtr;
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m_lduStartPtr = startPtr;
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m_lduEndPtr = m_dataPtr + P25_LDU_FRAME_LENGTH_SAMPLES - P25_SYNC_LENGTH_SAMPLES - 1U;
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if (m_lduEndPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
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@ -407,6 +359,70 @@ bool CP25RX::correlateSync()
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return false;
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}
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void CP25RX::calculateLevels(uint16_t start, uint16_t count)
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{
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q15_t maxPos = -16000;
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q15_t minPos = 16000;
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q15_t maxNeg = 16000;
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q15_t minNeg = -16000;
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for (uint16_t i = 0U; i < count; i++) {
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q15_t sample = m_buffer[start];
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if (sample > 0) {
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if (sample > maxPos)
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maxPos = sample;
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if (sample < minPos)
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minPos = sample;
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} else {
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if (sample < maxNeg)
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maxNeg = sample;
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if (sample > minNeg)
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minNeg = sample;
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}
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start += P25_RADIO_SYMBOL_LENGTH;
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if (start >= P25_LDU_FRAME_LENGTH_SAMPLES)
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start -= P25_LDU_FRAME_LENGTH_SAMPLES;
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}
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q15_t posThresh = (maxPos + minPos) >> 1;
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q15_t negThresh = (maxNeg + minNeg) >> 1;
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q15_t centre = (posThresh + negThresh) >> 1;
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q15_t threshold = posThresh - centre;
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DEBUG5("P25RX: pos/neg/centre/threshold", posThresh, negThresh, centre, threshold);
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if (m_averagePtr == NOAVEPTR) {
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for (uint8_t i = 0U; i < 16U; i++) {
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m_centre[i] = centre;
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m_threshold[i] = threshold;
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}
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m_averagePtr = 0U;
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} else {
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m_centre[m_averagePtr] = centre;
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m_threshold[m_averagePtr] = threshold;
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m_averagePtr++;
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if (m_averagePtr >= 16U)
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m_averagePtr = 0U;
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}
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m_centreVal = 0;
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m_thresholdVal = 0;
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for (uint8_t i = 0U; i < 16U; i++) {
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m_centreVal += m_centre[i];
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m_thresholdVal += m_threshold[i];
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}
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m_centreVal >>= 4;
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m_thresholdVal >>= 4;
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}
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void CP25RX::samplesToBits(uint16_t start, uint16_t count, uint8_t* buffer, uint16_t offset, q15_t centre, q15_t threshold)
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{
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for (uint16_t i = 0U; i < count; i++) {
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@ -467,9 +483,6 @@ void CP25RX::writeSync(uint16_t start)
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q15_t sync[P25_SYNC_LENGTH_SYMBOLS];
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for (uint16_t i = 0U; i < P25_SYNC_LENGTH_SYMBOLS; i++) {
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if (i == (P25_SYNC_LENGTH_SYMBOLS - 1U))
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DEBUG4("P25RX: sync1/sync2/start", m_hdrSyncPtr, m_lduSyncPtr, start);
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sync[i] = m_buffer[start];
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start += P25_RADIO_SYMBOL_LENGTH;
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