MMDVM/P25RX.cpp
LucaMarche IZ1MLT 694b83123a
Update 48k version
In to NXDN possible problem on sinc filter anc isinc filter, think they must be recalculated but do not know how to do it. On D-STAR, DMR, C4FM and P25 it work.
2018-05-30 08:54:45 +02:00

526 lines
15 KiB
C++

/*
* Copyright (C) 2009-2017 by Jonathan Naylor G4KLX
* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "Config.h"
#include "Globals.h"
#include "P25RX.h"
#include "Utils.h"
const q15_t SCALING_FACTOR = 18750; // Q15(0.57)
const uint8_t CORRELATION_COUNTDOWN = 10U;//5U;
const uint8_t MAX_SYNC_BIT_START_ERRS = 2U;
const uint8_t MAX_SYNC_BIT_RUN_ERRS = 4U;
const uint8_t MAX_SYNC_SYMBOLS_ERRS = 2U;
const uint8_t BIT_MASK_TABLE[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };
#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;
CP25RX::CP25RX() :
m_state(P25RXS_NONE),
m_bitBuffer(),
m_buffer(),
m_bitPtr(0U),
m_dataPtr(0U),
m_hdrStartPtr(NOENDPTR),
m_lduStartPtr(NOENDPTR),
m_lduEndPtr(NOENDPTR),
m_minSyncPtr(NOENDPTR),
m_maxSyncPtr(NOENDPTR),
m_hdrSyncPtr(NOENDPTR),
m_lduSyncPtr(NOENDPTR),
m_maxCorr(0),
m_lostCount(0U),
m_countdown(0U),
m_centre(),
m_centreVal(0),
m_threshold(),
m_thresholdVal(0),
m_averagePtr(NOAVEPTR),
m_rssiAccum(0U),
m_rssiCount(0U),
m_duid(0U)
{
}
void CP25RX::reset()
{
m_state = P25RXS_NONE;
m_dataPtr = 0U;
m_bitPtr = 0U;
m_maxCorr = 0;
m_averagePtr = NOAVEPTR;
m_hdrStartPtr = NOENDPTR;
m_lduStartPtr = NOENDPTR;
m_lduEndPtr = NOENDPTR;
m_hdrSyncPtr = NOENDPTR;
m_lduSyncPtr = NOENDPTR;
m_minSyncPtr = NOENDPTR;
m_maxSyncPtr = NOENDPTR;
m_centreVal = 0;
m_thresholdVal = 0;
m_lostCount = 0U;
m_countdown = 0U;
m_rssiAccum = 0U;
m_rssiCount = 0U;
m_duid = 0U;
}
void CP25RX::samples(const q15_t* samples, uint16_t* rssi, uint8_t length)
{
for (uint8_t i = 0U; i < length; i++) {
q15_t sample = samples[i];
m_rssiAccum += rssi[i];
m_rssiCount++;
m_bitBuffer[m_bitPtr] <<= 1;
if (sample < 0)
m_bitBuffer[m_bitPtr] |= 0x01U;
m_buffer[m_dataPtr] = sample;
switch (m_state) {
case P25RXS_HDR:
processHdr(sample);
break;
case P25RXS_LDU:
processLdu(sample);
break;
default:
processNone(sample);
break;
}
m_dataPtr++;
if (m_dataPtr >= P25_LDU_FRAME_LENGTH_SAMPLES) {
m_dataPtr = 0U;
m_duid = 0U;
}
m_bitPtr++;
if (m_bitPtr >= P25_RADIO_SYMBOL_LENGTH)
m_bitPtr = 0U;
}
}
void CP25RX::processNone(q15_t sample)
{
bool ret = correlateSync();
if (ret) {
// On the first sync, start the countdown to the state change
if (m_countdown == 0U) {
m_rssiAccum = 0U;
m_rssiCount = 0U;
io.setDecode(true);
io.setADCDetection(true);
m_averagePtr = NOAVEPTR;
m_countdown = CORRELATION_COUNTDOWN;
}
}
if (m_countdown > 0U)
m_countdown--;
if (m_countdown == 1U) {
// 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)
m_minSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
m_maxSyncPtr = m_hdrSyncPtr + P25_HDR_FRAME_LENGTH_SAMPLES + 1U;
if (m_maxSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
m_maxSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
m_state = P25RXS_HDR;
m_countdown = 0U;
}
}
void CP25RX::processHdr(q15_t sample)
{
if (m_minSyncPtr < m_maxSyncPtr) {
if (m_dataPtr >= m_minSyncPtr && m_dataPtr <= m_maxSyncPtr)
correlateSync();
} else {
if (m_dataPtr >= m_minSyncPtr || m_dataPtr <= m_maxSyncPtr)
correlateSync();
}
if (m_dataPtr == m_maxSyncPtr) {
uint16_t nidStartPtr = m_hdrStartPtr + P25_SYNC_LENGTH_SAMPLES;
if (nidStartPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
nidStartPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
uint8_t nid[2U];
samplesToBits(nidStartPtr, (2U * 4U), nid, 0U, m_centreVal, m_thresholdVal);
// DEBUG3("P25RX: nid (b0 - b1)", nid[0U], nid[1U]);
m_duid = nid[1U] & 0x0F;
switch (m_duid) {
case P25_DUID_HDU: {
calculateLevels(m_hdrStartPtr, P25_HDR_FRAME_LENGTH_SYMBOLS);
DEBUG4("P25RX: sync found in Hdr pos/centre/threshold", m_hdrSyncPtr, m_centreVal, m_thresholdVal);
uint8_t frame[P25_HDR_FRAME_LENGTH_BYTES + 1U];
samplesToBits(m_hdrStartPtr, P25_HDR_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
frame[0U] = 0x01U;
serial.writeP25Hdr(frame, P25_HDR_FRAME_LENGTH_BYTES + 1U);
}
break;
case P25_DUID_TSDU: {
calculateLevels(m_hdrStartPtr, P25_TSDU_FRAME_LENGTH_SYMBOLS);
DEBUG4("P25RX: sync found in TSDU pos/centre/threshold", m_hdrSyncPtr, m_centreVal, m_thresholdVal);
uint8_t frame[P25_TSDU_FRAME_LENGTH_BYTES + 1U];
samplesToBits(m_hdrStartPtr, P25_TSDU_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
frame[0U] = 0x01U;
serial.writeP25Hdr(frame, P25_TSDU_FRAME_LENGTH_BYTES + 1U);
}
break;
case P25_DUID_TDU: {
calculateLevels(m_hdrStartPtr, P25_TERM_FRAME_LENGTH_SYMBOLS);
DEBUG4("P25RX: sync found in TDU pos/centre/threshold", m_hdrSyncPtr, m_centreVal, m_thresholdVal);
uint8_t frame[P25_TERM_FRAME_LENGTH_BYTES + 1U];
samplesToBits(m_hdrStartPtr, P25_TERM_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
frame[0U] = 0x01U;
serial.writeP25Hdr(frame, P25_TERM_FRAME_LENGTH_BYTES + 1U);
}
break;
case P25_DUID_TDULC: {
calculateLevels(m_hdrStartPtr, P25_TERMLC_FRAME_LENGTH_SYMBOLS);
DEBUG4("P25RX: sync found in TDULC pos/centre/threshold", m_hdrSyncPtr, m_centreVal, m_thresholdVal);
uint8_t frame[P25_TERMLC_FRAME_LENGTH_BYTES + 1U];
samplesToBits(m_hdrStartPtr, P25_TERMLC_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
frame[0U] = 0x01U;
serial.writeP25Hdr(frame, P25_TERMLC_FRAME_LENGTH_BYTES + 1U);
}
break;
default:
break;
}
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;
m_maxSyncPtr = m_lduSyncPtr + 1U;
if (m_maxSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
m_maxSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
m_state = P25RXS_LDU;
m_maxCorr = 0;
}
}
void CP25RX::processLdu(q15_t sample)
{
if (m_minSyncPtr < m_maxSyncPtr) {
if (m_dataPtr >= m_minSyncPtr && m_dataPtr <= m_maxSyncPtr)
correlateSync();
} else {
if (m_dataPtr >= m_minSyncPtr || m_dataPtr <= m_maxSyncPtr)
correlateSync();
}
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_minSyncPtr = m_lduSyncPtr + P25_LDU_FRAME_LENGTH_SAMPLES - 1U;
if (m_minSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
m_minSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
m_maxSyncPtr = m_lduSyncPtr + 1U;
if (m_maxSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
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);
// We've not seen a data sync for too long, signal RXLOST and change to RX_NONE
m_lostCount--;
if (m_lostCount == 0U) {
DEBUG1("P25RX: sync timed out, lost lock");
io.setDecode(false);
io.setADCDetection(false);
serial.writeP25Lost();
m_state = P25RXS_NONE;
m_lduEndPtr = NOENDPTR;
m_averagePtr = NOAVEPTR;
m_countdown = 0U;
m_maxCorr = 0;
m_duid = 0U;
} else {
frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
writeRSSILdu(frame);
m_maxCorr = 0;
}
}
}
bool CP25RX::correlateSync()
{
if (countBits32((m_bitBuffer[m_bitPtr] & P25_SYNC_SYMBOLS_MASK) ^ P25_SYNC_SYMBOLS) <= MAX_SYNC_SYMBOLS_ERRS) {
uint16_t ptr = m_dataPtr + P25_LDU_FRAME_LENGTH_SAMPLES - P25_SYNC_LENGTH_SAMPLES + P25_RADIO_SYMBOL_LENGTH;
if (ptr >= P25_LDU_FRAME_LENGTH_SAMPLES)
ptr -= P25_LDU_FRAME_LENGTH_SAMPLES;
q31_t corr = 0;
q15_t min = 16000;
q15_t max = -16000;
for (uint8_t i = 0U; i < P25_SYNC_LENGTH_SYMBOLS; i++) {
q15_t val = m_buffer[ptr];
if (val > max)
max = val;
if (val < min)
min = val;
switch (P25_SYNC_SYMBOLS_VALUES[i]) {
case +3:
corr -= (val + val + val);
break;
case +1:
corr -= val;
break;
case -1:
corr += val;
break;
default: // -3
corr += (val + val + val);
break;
}
ptr += P25_RADIO_SYMBOL_LENGTH;
if (ptr >= P25_LDU_FRAME_LENGTH_SAMPLES)
ptr -= P25_LDU_FRAME_LENGTH_SAMPLES;
}
if (corr > m_maxCorr) {
if (m_averagePtr == NOAVEPTR) {
m_centreVal = (max + min) >> 1;
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)
maxErrs = MAX_SYNC_BIT_START_ERRS;
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_lostCount = MAX_SYNC_FRAMES;
m_lduSyncPtr = m_dataPtr;
// These are the positions of the start and end of an LDU
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)
m_lduEndPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
if (m_state == P25RXS_NONE) {
m_hdrSyncPtr = m_dataPtr;
// This is the position of the start of a HDR
m_hdrStartPtr = startPtr;
// These are the range of positions for a sync for an LDU following a HDR
m_minSyncPtr = m_dataPtr + P25_HDR_FRAME_LENGTH_SAMPLES - 1U;
if (m_minSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
m_minSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
m_maxSyncPtr = m_dataPtr + P25_HDR_FRAME_LENGTH_SAMPLES + 1U;
if (m_maxSyncPtr >= P25_LDU_FRAME_LENGTH_SAMPLES)
m_maxSyncPtr -= P25_LDU_FRAME_LENGTH_SAMPLES;
}
return true;
}
}
}
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++) {
q15_t sample = m_buffer[start] - centre;
if (sample < -threshold) {
WRITE_BIT1(buffer, offset, false);
offset++;
WRITE_BIT1(buffer, offset, true);
offset++;
} else if (sample < 0) {
WRITE_BIT1(buffer, offset, false);
offset++;
WRITE_BIT1(buffer, offset, false);
offset++;
} else if (sample < threshold) {
WRITE_BIT1(buffer, offset, true);
offset++;
WRITE_BIT1(buffer, offset, false);
offset++;
} else {
WRITE_BIT1(buffer, offset, true);
offset++;
WRITE_BIT1(buffer, offset, true);
offset++;
}
start += P25_RADIO_SYMBOL_LENGTH;
if (start >= P25_LDU_FRAME_LENGTH_SAMPLES)
start -= P25_LDU_FRAME_LENGTH_SAMPLES;
}
}
void CP25RX::writeRSSILdu(uint8_t* ldu)
{
#if defined(SEND_RSSI_DATA)
if (m_rssiCount > 0U) {
uint16_t rssi = m_rssiAccum / m_rssiCount;
ldu[217U] = (rssi >> 8) & 0xFFU;
ldu[218U] = (rssi >> 0) & 0xFFU;
serial.writeP25Ldu(ldu, P25_LDU_FRAME_LENGTH_BYTES + 3U);
} else {
serial.writeP25Ldu(ldu, P25_LDU_FRAME_LENGTH_BYTES + 1U);
}
#else
serial.writeP25Ldu(ldu, P25_LDU_FRAME_LENGTH_BYTES + 1U);
#endif
m_rssiAccum = 0U;
m_rssiCount = 0U;
}