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Make NXDN sync detection more lenient when receiving a transmission.

nxdn
Jonathan Naylor 2018-02-08 18:40:23 +00:00
parent 9f28d2f69a
commit 1d4bd4e409
1 changed files with 11 additions and 4 deletions
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15
NXDNRX.cpp
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@ -23,9 +23,10 @@
const q15_t SCALING_FACTOR = 18750; // Q15(0.55)
const uint8_t MAX_FSW_BIT_ERRS = 1U;
const uint8_t MAX_FSW_BIT_START_ERRS = 1U;
const uint8_t MAX_FSW_BIT_RUN_ERRS = 3U;
const uint8_t MAX_FSW_SYMBOLS_ERRS = 1U;
const uint8_t MAX_FSW_SYMBOLS_ERRS = 2U;
const uint8_t BIT_MASK_TABLE[] = {0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U};
@ -255,11 +256,17 @@ bool CNXDNRX::correlateFSW()
uint8_t sync[NXDN_FSW_BYTES_LENGTH];
samplesToBits(startPtr, NXDN_FSW_LENGTH_SYMBOLS, sync, 0U, m_centreVal, m_thresholdVal);
uint8_t errs = 0U;
uint8_t maxErrs;
if (m_state == NXDNRXS_NONE)
maxErrs = MAX_FSW_BIT_START_ERRS;
else
maxErrs = MAX_FSW_BIT_RUN_ERRS;
uint8_t errs = 0U;
for (uint8_t i = 0U; i < NXDN_FSW_BYTES_LENGTH; i++)
errs += countBits8((sync[i] & NXDN_FSW_BYTES_MASK[i]) ^ NXDN_FSW_BYTES[i]);
if (errs <= MAX_FSW_BIT_ERRS) {
if (errs <= maxErrs) {
m_maxCorr = corr;
m_lostCount = MAX_FSW_FRAMES;
m_fswPtr = m_dataPtr;