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moved extract frame back into proc_pocsag

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This commit is contained in:
heurist1 2021-11-07 09:00:00 +00:00
parent 318720f364
commit 40654aba55
5 changed files with 496 additions and 559 deletions
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1
firmware/baseband/CMakeLists.txt
View File

@ -431,7 +431,6 @@ DeclareTargets(POOK ook)
set(MODE_CPPSRC
proc_pocsag.cpp
extract_frame_pager.cpp
)
DeclareTargets(PPOC pocsag)

451
firmware/baseband/extract_frame_pager.cpp
View File

@ -1,451 +0,0 @@
#include "extract_frame_pager.hpp"
#include <algorithm> // std::max
#include <cmath>
#define BAUD_STABLE (104)
#define MAX_CONSEC_SAME (32)
#define MAX_WITHOUT_SINGLE (64)
#define MAX_BAD_TRANS (10)
#define M_SYNC (0x7cd215d8)
#define M_NOTSYNC (0x832dea27)
#define M_IDLE (0x7a89c197)
// ====================================================================
//
// ====================================================================
inline int bitsDiff(unsigned long left, unsigned long right)
{
unsigned long xord = left ^ right;
int count = 0;
for (int i = 0; i < 32; i++)
{
if ((xord & 0x01) != 0) ++count;
xord = xord >> 1;
}
return(count);
}
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
extract_frame_pager::extract_frame_pager()
{
init();
}
// ====================================================================
//
// ====================================================================
extract_frame_pager::~extract_frame_pager()
{
}
// ====================================================================
//
// ====================================================================
void extract_frame_pager::init()
{
m_averageSymbolLen_1024 = m_maxSymSamples_1024;
m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
m_badTransitions = 0;
m_bitsStart = 0;
m_bitsEnd = 0;
m_inverted = false;
resetVals();
}
// ====================================================================
//
// ====================================================================
void extract_frame_pager::resetVals()
{
// Set up the xtraction mode
m_detectionMode = DM_DYNAMIC;
// Reset the parameters
// --------------------
m_goodTransitions = 0;
m_badTransitions = 0;
m_averageSymbolLen_1024 = m_maxSymSamples_1024;
m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
m_valMid = 0;
// And reset the counts
// --------------------
m_lastTransPos_1024 = 0;
m_lastBitPos_1024 = 0;
m_lastSample = 0;
m_sampleNo = 0;
m_nextBitPos_1024 = m_maxSymSamples_1024;
m_nextBitPosInt = (long)m_nextBitPos_1024;
// Extraction
m_fifo.numBits = 0;
m_gotSync = false;
m_numCode = 0;
}
// ====================================================================
//
// ====================================================================
void extract_frame_pager::setFrameExtractParams(long a_samplesPerSec, long a_maxBaud, long a_minBaud, long maxRunOfSameValue)
{
m_samplesPerSec = a_samplesPerSec;
m_minSymSamples_1024 = (uint32_t)(1024.0f * (float)a_samplesPerSec / (float)a_maxBaud);
m_maxSymSamples_1024 = (uint32_t)(1024.0f*(float)a_samplesPerSec / (float)a_minBaud);
m_maxRunOfSameValue = maxRunOfSameValue;
m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
m_averageSymbolLen_1024 = m_maxSymSamples_1024;
m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
m_nextBitPos_1024 = m_averageSymbolLen_1024 / 2;
m_nextBitPosInt = m_nextBitPos_1024 >> 10;
init();
}
// ====================================================================
//
// ====================================================================
int extract_frame_pager::processDemodulatedSamples(float * sampleBuff, int noOfSamples)
{
bool transition = false;
uint32_t samplePos_1024 = 0;
uint32_t len_1024 = 0;
// Loop through the block of data
// ------------------------------
for (int pos = 0; pos < noOfSamples; ++pos)
{
m_sample = sampleBuff[pos];
m_valMid += (m_sample - m_valMid) / 1024.0f;
++m_sampleNo;
// Detect Transition
// -----------------
transition = ! ((m_lastSample < m_valMid) ^ (m_sample >= m_valMid)); // use XOR for speed
// If this is a transition
// -----------------------
if (transition)
{
// Calculate samples since last trans
// ----------------------------------
int32_t fractional_1024 = (int32_t)(((m_sample - m_valMid)*1024) / (m_sample - m_lastSample));
if (fractional_1024 < 0) { fractional_1024 = -fractional_1024; }
samplePos_1024 = (m_sampleNo<<10)-fractional_1024;
len_1024 = samplePos_1024 - m_lastTransPos_1024;
m_lastTransPos_1024 = samplePos_1024;
// If symbol is large enough to be valid
// -------------------------------------
if (len_1024 > m_minSymSamples_1024)
{
// Check for shortest good transition
// ----------------------------------
if ((len_1024 < m_shortestGoodTrans_1024) &&
(m_goodTransitions < BAUD_STABLE)) // detect change of symbol size
{
int32_t fractionOfShortest_1024 = (len_1024<<10) / m_shortestGoodTrans_1024;
// If currently at half the baud rate
// ----------------------------------
if ((fractionOfShortest_1024 > 410) && (fractionOfShortest_1024 < 614)) // 0.4 and 0.6
{
m_averageSymbolLen_1024 /= 2;
m_shortestGoodTrans_1024 = len_1024;
}
// If currently at the wrong baud rate
// -----------------------------------
else if (fractionOfShortest_1024 < 768) // 0.75
{
m_averageSymbolLen_1024 = len_1024;
m_shortestGoodTrans_1024 = len_1024;
m_goodTransitions = 0;
m_lastSingleBitPos_1024 = samplePos_1024 - len_1024;
}
}
// Calc the number of bits since events
// ------------------------------------
int32_t halfSymbol_1024 = m_averageSymbolLen_1024 / 2;
int bitsSinceLastTrans = max((uint32_t)1, (len_1024+halfSymbol_1024) / m_averageSymbolLen_1024 );
int bitsSinceLastSingle = (((m_sampleNo<<10)-m_lastSingleBitPos_1024) + halfSymbol_1024) / m_averageSymbolLen_1024;
// Check for single bit
// --------------------
if (bitsSinceLastTrans == 1)
{
m_lastSingleBitPos_1024 = samplePos_1024;
}
// If too long since last transition
// ---------------------------------
if (bitsSinceLastTrans > MAX_CONSEC_SAME)
{
resetVals();
}
// If too long sice last single bit
// --------------------------------
else if (bitsSinceLastSingle > MAX_WITHOUT_SINGLE)
{
resetVals();
}
else
{
// If this is a good transition
// ----------------------------
int32_t offsetFromExtectedTransition_1024 = len_1024 - (bitsSinceLastTrans*m_averageSymbolLen_1024);
if (offsetFromExtectedTransition_1024 < 0) { offsetFromExtectedTransition_1024 = -offsetFromExtectedTransition_1024; }
if (offsetFromExtectedTransition_1024 < (m_averageSymbolLen_1024 / 4)) // Has to be within 1/4 of symbol to be good
{
++m_goodTransitions;
uint32_t bitsCount = min((uint32_t)BAUD_STABLE, m_goodTransitions);
uint32_t propFromPrevious = m_averageSymbolLen_1024*bitsCount;
uint32_t propFromCurrent = (len_1024 / bitsSinceLastTrans);
m_averageSymbolLen_1024 = (propFromPrevious + propFromCurrent) / (bitsCount + 1);
m_badTransitions = 0;
//if ( len < m_shortestGoodTrans ){m_shortestGoodTrans = len;}
// Store the old symbol size
if (m_goodTransitions >= BAUD_STABLE)
{
m_lastStableSymbolLen_1024 = m_averageSymbolLen_1024;
}
}
// Not a good transition
// ---------------------
else
{
// m_goodTransitions = 0;
}
}
// Set the point of the last bit if not yet stable
// -----------------------------------------------
if ((m_goodTransitions < BAUD_STABLE) || (m_badTransitions > 0))
{
m_lastBitPos_1024 = samplePos_1024 - (m_averageSymbolLen_1024 / 2);
}
// Calculate the exact positiom of the next bit
// --------------------------------------------
int32_t thisPlusHalfsymbol_1024 = samplePos_1024 + (m_averageSymbolLen_1024/2);
int32_t lastPlusSymbol = m_lastBitPos_1024 + m_averageSymbolLen_1024;
m_nextBitPos_1024 = lastPlusSymbol + ((thisPlusHalfsymbol_1024 - lastPlusSymbol) / 16);
// Check for bad pos error
// -----------------------
if (m_nextBitPos_1024 < samplePos_1024) m_nextBitPos_1024 += m_averageSymbolLen_1024;
// Calculate integer sample after next bit
// ---------------------------------------
m_nextBitPosInt = (m_nextBitPos_1024>>10) + 1;
} // symbol is large enough to be valid
else
{
// Bad transition, so reset the counts
// -----------------------------------
++m_badTransitions;
if (m_badTransitions > MAX_BAD_TRANS)
{
resetVals();
}
}
} // end of if transition
else
{
//TRACE("Len too small %f",len);
}
// Reached the point of the next bit
// ---------------------------------
if (m_sampleNo >= m_nextBitPosInt)
{
// Everything is good so extract a bit
// -----------------------------------
if (m_goodTransitions > 20)
{
// Store value at the center of bit
// --------------------------------
storeBit();
}
// Check for long 1 or zero
// ------------------------
int bitsSinceLastTrans = ((m_sampleNo<<10) - m_lastTransPos_1024) / m_averageSymbolLen_1024;
if (bitsSinceLastTrans > m_maxRunOfSameValue)
{
resetVals();
}
// Store the point of the last bit
// -------------------------------
m_lastBitPos_1024 = m_nextBitPos_1024;
// Calculate the exact point of the next bit
// -----------------------------------------
m_nextBitPos_1024 += m_averageSymbolLen_1024;
// Look for the bit after the next bit pos
// ---------------------------------------
m_nextBitPosInt = (m_nextBitPos_1024>>10) + 1;
} // Reached the point of the next bit
m_lastSample = m_sample;
} // Loop through the block of data
return getNoOfBits();
}
// ====================================================================
//
// ====================================================================
void extract_frame_pager::storeBit()
{
if (++m_bitsStart >= BIT_BUF_SIZE) { m_bitsStart = 0; }
// Calculate the bit value
float sample = (m_sample + m_lastSample) / 2;
//int32_t sample_1024 = m_sample_1024;
bool bit = sample > m_valMid;
// If buffer not full
if (m_bitsStart != m_bitsEnd)
{
// Decide on output val
if (bit)
{
m_bits[m_bitsStart] = 0;
}
else
{
m_bits[m_bitsStart] = 1;
}
}
// Throw away bits if the buffer is full
else
{
if (--m_bitsStart <= -1)
{
m_bitsStart = BIT_BUF_SIZE - 1;
}
}
}
// ====================================================================
//
// ====================================================================
int extract_frame_pager::extractFrames()
{
int msgCnt = 0;
// While there is unread data in the bits buffer
//----------------------------------------------
while (getNoOfBits() > 0)
{
m_fifo.codeword = (m_fifo.codeword << 1) + getBit();
m_fifo.numBits++;
// If number of bits in fifo equals 32
//------------------------------------
if (m_fifo.numBits >= 32)
{
// Not got sync
// ------------
if (!m_gotSync)
{
if (bitsDiff(m_fifo.codeword, M_SYNC) <= 2)
{
m_inverted = false;
m_gotSync = true;
m_numCode = -1;
m_fifo.numBits = 0;
//TRACE("SYNC %x %d\n", m_fifo.codeword, m_numCode);
}
else if (bitsDiff(m_fifo.codeword, M_NOTSYNC) <= 2)
{
m_inverted = true;
m_gotSync = true;
m_numCode = -1;
m_fifo.numBits = 0;
//TRACE("ISYNC %x %d\n", m_fifo.codeword, m_numCode);
}
else
{
// Cause it to load one more bit
m_fifo.numBits = 31;
}
} // Not got sync
else
{
// Increment the word count
// ------------------------
++m_numCode; // It got set to -1 when a sync was found, now count the 16 words
uint32_t val = m_inverted ? ~m_fifo.codeword : m_fifo.codeword;
OnDataWord(val, m_numCode);
//TRACE("WORD %x %d\n", m_fifo.codeword, m_numCode);
// If at the end of a 16 word block
// --------------------------------
if (m_numCode >= 15)
{
msgCnt += OnDataFrame(m_numCode+1, (m_samplesPerSec<<10) / m_lastStableSymbolLen_1024);
m_gotSync = false;
m_numCode = -1;
}
m_fifo.numBits = 0;
}
} // If number of bits in fifo equals 32
} // While there is unread data in the bits buffer
return msgCnt;
} // extractFrames
// ====================================================================
//
// ====================================================================
//
// ====================================================================
short extract_frame_pager::getBit()
{
if (m_bitsEnd != m_bitsStart)
{
if (++m_bitsEnd >= BIT_BUF_SIZE)
{
m_bitsEnd = 0;
}
return m_bits[m_bitsEnd];
}
else
{
return -1;
}
}
// ====================================================================
//
// ====================================================================
int extract_frame_pager::getNoOfBits()
{
int bits = m_bitsEnd - m_bitsStart;
if (bits < 0) { bits += BIT_BUF_SIZE; }
return bits;
}
// ====================================================================
//
// ====================================================================
uint32_t extract_frame_pager::getRate()
{
return ((m_samplesPerSec<<10)+512) / m_lastStableSymbolLen_1024;
}

98
firmware/baseband/extract_frame_pager.hpp
View File

@ -1,98 +0,0 @@
/*
* This file is part of PortaPack.
*
* 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, 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; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef __EXTRACT_FRAME_PAGER_H__
#define __EXTRACT_FRAME_PAGER_H__
#include <bitset>
using namespace std;
// This class extracts a POCSAG message from a FM demodulated sample stream
// TODO extend to also process FLEX frames
#define MAX_CODEWORDS (16)
class extract_frame_pager
{
public:
struct FIFOStruct {
unsigned long codeword;
int numBits;
};
#define BIT_BUF_SIZE (64)
enum BitsState { BS_SEARCHING, BS_SYNC, BS_LOCKED };
enum DetectionMode { DM_STATIC, DM_DYNAMIC, DM_DIFFERENTIAL };
extract_frame_pager();
virtual ~extract_frame_pager();
void resetVals();
void setFrameExtractParams(long a_samplesPerSec, long a_maxBaud = 8000, long a_minBaud = 200, long maxRunOfSameValue = 32);
int processDemodulatedSamples(float * sampleBuff, int noOfSamples);
int extractFrames();
virtual int OnDataFrame(int len, int baud) = 0;
virtual int OnDataWord(uint32_t word, int pos) = 0;
void init();
void storeBit();
short getBit();
int getNoOfBits();
uint32_t getRate();
protected:
uint32_t m_averageSymbolLen_1024;
uint32_t m_lastStableSymbolLen_1024;
uint32_t m_samplesPerSec;
uint32_t m_goodTransitions;
uint32_t m_badTransitions;
private:
uint32_t m_sampleNo;
float m_sample;
float m_valMid;
float m_lastSample;
BitsState m_state;
uint32_t m_lastTransPos_1024;
uint32_t m_lastSingleBitPos_1024;
uint32_t m_nextBitPosInt; // Integer rounded up version to save on ops
uint32_t m_nextBitPos_1024;
uint32_t m_lastBitPos_1024;
uint32_t m_shortestGoodTrans_1024;
uint32_t m_minSymSamples_1024;
uint32_t m_maxSymSamples_1024;
uint32_t m_maxRunOfSameValue;
bitset<(size_t)BIT_BUF_SIZE> m_bits;
long m_bitsStart;
long m_bitsEnd;
DetectionMode m_detectionMode;
FIFOStruct m_fifo;
bool m_gotSync;
int m_numCode;
bool m_inverted;
};
#endif/*__EXTRACT_FRAME_PAGER_H__*/

431
firmware/baseband/proc_pocsag.cpp
View File

@ -28,6 +28,9 @@
#include <cstdint>
#include <cstddef>
#include <algorithm> // std::max
#include <cmath>
void POCSAGProcessor::execute(const buffer_c8_t& buffer) {
// This is called at 1500Hz
@ -74,10 +77,10 @@ int POCSAGProcessor::OnDataFrame(int len, int baud)
void POCSAGProcessor::on_message(const Message* const message) {
if (message->id == Message::ID::POCSAGConfigure)
configure(*reinterpret_cast<const POCSAGConfigureMessage*>(message));
configure();
}
void POCSAGProcessor::configure(const POCSAGConfigureMessage& message) {
void POCSAGProcessor::configure() {
constexpr size_t decim_0_input_fs = baseband_fs;
constexpr size_t decim_0_output_fs = decim_0_input_fs / decim_0.decimation_factor;
@ -105,6 +108,430 @@ void POCSAGProcessor::configure(const POCSAGConfigureMessage& message) {
configured = true;
}
// -----------------------------
// Frame extractraction methods
// -----------------------------
#define BAUD_STABLE (104)
#define MAX_CONSEC_SAME (32)
#define MAX_WITHOUT_SINGLE (64)
#define MAX_BAD_TRANS (10)
#define M_SYNC (0x7cd215d8)
#define M_NOTSYNC (0x832dea27)
#define M_IDLE (0x7a89c197)
// ====================================================================
//
// ====================================================================
inline int bitsDiff(unsigned long left, unsigned long right)
{
unsigned long xord = left ^ right;
int count = 0;
for (int i = 0; i < 32; i++)
{
if ((xord & 0x01) != 0) ++count;
xord = xord >> 1;
}
return(count);
}
// ====================================================================
//
// ====================================================================
void POCSAGProcessor::initFrameExtraction()
{
m_averageSymbolLen_1024 = m_maxSymSamples_1024;
m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
m_badTransitions = 0;
m_bitsStart = 0;
m_bitsEnd = 0;
m_inverted = false;
resetVals();
}
// ====================================================================
//
// ====================================================================
void POCSAGProcessor::resetVals()
{
// Reset the parameters
// --------------------
m_goodTransitions = 0;
m_badTransitions = 0;
m_averageSymbolLen_1024 = m_maxSymSamples_1024;
m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
m_valMid = 0;
// And reset the counts
// --------------------
m_lastTransPos_1024 = 0;
m_lastBitPos_1024 = 0;
m_lastSample = 0;
m_sampleNo = 0;
m_nextBitPos_1024 = m_maxSymSamples_1024;
m_nextBitPosInt = (long)m_nextBitPos_1024;
// Extraction
m_fifo.numBits = 0;
m_gotSync = false;
m_numCode = 0;
}
// ====================================================================
//
// ====================================================================
void POCSAGProcessor::setFrameExtractParams(long a_samplesPerSec, long a_maxBaud, long a_minBaud, long maxRunOfSameValue)
{
m_samplesPerSec = a_samplesPerSec;
m_minSymSamples_1024 = (uint32_t)(1024.0f * (float)a_samplesPerSec / (float)a_maxBaud);
m_maxSymSamples_1024 = (uint32_t)(1024.0f*(float)a_samplesPerSec / (float)a_minBaud);
m_maxRunOfSameValue = maxRunOfSameValue;
m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
m_averageSymbolLen_1024 = m_maxSymSamples_1024;
m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
m_nextBitPos_1024 = m_averageSymbolLen_1024 / 2;
m_nextBitPosInt = m_nextBitPos_1024 >> 10;
initFrameExtraction();
}
// ====================================================================
//
// ====================================================================
int POCSAGProcessor::processDemodulatedSamples(float * sampleBuff, int noOfSamples)
{
bool transition = false;
uint32_t samplePos_1024 = 0;
uint32_t len_1024 = 0;
// Loop through the block of data
// ------------------------------
for (int pos = 0; pos < noOfSamples; ++pos)
{
m_sample = sampleBuff[pos];
m_valMid += (m_sample - m_valMid) / 1024.0f;
++m_sampleNo;
// Detect Transition
// -----------------
transition = ! ((m_lastSample < m_valMid) ^ (m_sample >= m_valMid)); // use XOR for speed
// If this is a transition
// -----------------------
if (transition)
{
// Calculate samples since last trans
// ----------------------------------
int32_t fractional_1024 = (int32_t)(((m_sample - m_valMid)*1024) / (m_sample - m_lastSample));
if (fractional_1024 < 0) { fractional_1024 = -fractional_1024; }
samplePos_1024 = (m_sampleNo<<10)-fractional_1024;
len_1024 = samplePos_1024 - m_lastTransPos_1024;
m_lastTransPos_1024 = samplePos_1024;
// If symbol is large enough to be valid
// -------------------------------------
if (len_1024 > m_minSymSamples_1024)
{
// Check for shortest good transition
// ----------------------------------
if ((len_1024 < m_shortestGoodTrans_1024) &&
(m_goodTransitions < BAUD_STABLE)) // detect change of symbol size
{
int32_t fractionOfShortest_1024 = (len_1024<<10) / m_shortestGoodTrans_1024;
// If currently at half the baud rate
// ----------------------------------
if ((fractionOfShortest_1024 > 410) && (fractionOfShortest_1024 < 614)) // 0.4 and 0.6
{
m_averageSymbolLen_1024 /= 2;
m_shortestGoodTrans_1024 = len_1024;
}
// If currently at the wrong baud rate
// -----------------------------------
else if (fractionOfShortest_1024 < 768) // 0.75
{
m_averageSymbolLen_1024 = len_1024;
m_shortestGoodTrans_1024 = len_1024;
m_goodTransitions = 0;
m_lastSingleBitPos_1024 = samplePos_1024 - len_1024;
}
}
// Calc the number of bits since events
// ------------------------------------
int32_t halfSymbol_1024 = m_averageSymbolLen_1024 / 2;
int bitsSinceLastTrans = max((uint32_t)1, (len_1024+halfSymbol_1024) / m_averageSymbolLen_1024 );
int bitsSinceLastSingle = (((m_sampleNo<<10)-m_lastSingleBitPos_1024) + halfSymbol_1024) / m_averageSymbolLen_1024;
// Check for single bit
// --------------------
if (bitsSinceLastTrans == 1)
{
m_lastSingleBitPos_1024 = samplePos_1024;
}
// If too long since last transition
// ---------------------------------
if (bitsSinceLastTrans > MAX_CONSEC_SAME)
{
resetVals();
}
// If too long sice last single bit
// --------------------------------
else if (bitsSinceLastSingle > MAX_WITHOUT_SINGLE)
{
resetVals();
}
else
{
// If this is a good transition
// ----------------------------
int32_t offsetFromExtectedTransition_1024 = len_1024 - (bitsSinceLastTrans*m_averageSymbolLen_1024);
if (offsetFromExtectedTransition_1024 < 0) { offsetFromExtectedTransition_1024 = -offsetFromExtectedTransition_1024; }
if (offsetFromExtectedTransition_1024 < ((int32_t)m_averageSymbolLen_1024 / 4)) // Has to be within 1/4 of symbol to be good
{
++m_goodTransitions;
uint32_t bitsCount = min((uint32_t)BAUD_STABLE, m_goodTransitions);
uint32_t propFromPrevious = m_averageSymbolLen_1024*bitsCount;
uint32_t propFromCurrent = (len_1024 / bitsSinceLastTrans);
m_averageSymbolLen_1024 = (propFromPrevious + propFromCurrent) / (bitsCount + 1);
m_badTransitions = 0;
//if ( len < m_shortestGoodTrans ){m_shortestGoodTrans = len;}
// Store the old symbol size
if (m_goodTransitions >= BAUD_STABLE)
{
m_lastStableSymbolLen_1024 = m_averageSymbolLen_1024;
}
}
}
// Set the point of the last bit if not yet stable
// -----------------------------------------------
if ((m_goodTransitions < BAUD_STABLE) || (m_badTransitions > 0))
{
m_lastBitPos_1024 = samplePos_1024 - (m_averageSymbolLen_1024 / 2);
}
// Calculate the exact positiom of the next bit
// --------------------------------------------
int32_t thisPlusHalfsymbol_1024 = samplePos_1024 + (m_averageSymbolLen_1024/2);
int32_t lastPlusSymbol = m_lastBitPos_1024 + m_averageSymbolLen_1024;
m_nextBitPos_1024 = lastPlusSymbol + ((thisPlusHalfsymbol_1024 - lastPlusSymbol) / 16);
// Check for bad pos error
// -----------------------
if (m_nextBitPos_1024 < samplePos_1024) m_nextBitPos_1024 += m_averageSymbolLen_1024;
// Calculate integer sample after next bit
// ---------------------------------------
m_nextBitPosInt = (m_nextBitPos_1024>>10) + 1;
} // symbol is large enough to be valid
else
{
// Bad transition, so reset the counts
// -----------------------------------
++m_badTransitions;
if (m_badTransitions > MAX_BAD_TRANS)
{
resetVals();
}
}
} // end of if transition
// Reached the point of the next bit
// ---------------------------------
if (m_sampleNo >= m_nextBitPosInt)
{
// Everything is good so extract a bit
// -----------------------------------
if (m_goodTransitions > 20)
{
// Store value at the center of bit
// --------------------------------
storeBit();
}
// Check for long 1 or zero
// ------------------------
uint32_t bitsSinceLastTrans = ((m_sampleNo<<10) - m_lastTransPos_1024) / m_averageSymbolLen_1024;
if (bitsSinceLastTrans > m_maxRunOfSameValue)
{
resetVals();
}
// Store the point of the last bit
// -------------------------------
m_lastBitPos_1024 = m_nextBitPos_1024;
// Calculate the exact point of the next bit
// -----------------------------------------
m_nextBitPos_1024 += m_averageSymbolLen_1024;
// Look for the bit after the next bit pos
// ---------------------------------------
m_nextBitPosInt = (m_nextBitPos_1024>>10) + 1;
} // Reached the point of the next bit
m_lastSample = m_sample;
} // Loop through the block of data
return getNoOfBits();
}
// ====================================================================
//
// ====================================================================
void POCSAGProcessor::storeBit()
{
if (++m_bitsStart >= BIT_BUF_SIZE) { m_bitsStart = 0; }
// Calculate the bit value
float sample = (m_sample + m_lastSample) / 2;
//int32_t sample_1024 = m_sample_1024;
bool bit = sample > m_valMid;
// If buffer not full
if (m_bitsStart != m_bitsEnd)
{
// Decide on output val
if (bit)
{
m_bits[m_bitsStart] = 0;
}
else
{
m_bits[m_bitsStart] = 1;
}
}
// Throw away bits if the buffer is full
else
{
if (--m_bitsStart <= -1)
{
m_bitsStart = BIT_BUF_SIZE - 1;
}
}
}
// ====================================================================
//
// ====================================================================
int POCSAGProcessor::extractFrames()
{
int msgCnt = 0;
// While there is unread data in the bits buffer
//----------------------------------------------
while (getNoOfBits() > 0)
{
m_fifo.codeword = (m_fifo.codeword << 1) + getBit();
m_fifo.numBits++;
// If number of bits in fifo equals 32
//------------------------------------
if (m_fifo.numBits >= 32)
{
// Not got sync
// ------------
if (!m_gotSync)
{
if (bitsDiff(m_fifo.codeword, M_SYNC) <= 2)
{
m_inverted = false;
m_gotSync = true;
m_numCode = -1;
m_fifo.numBits = 0;
}
else if (bitsDiff(m_fifo.codeword, M_NOTSYNC) <= 2)
{
m_inverted = true;
m_gotSync = true;
m_numCode = -1;
m_fifo.numBits = 0;
}
else
{
// Cause it to load one more bit
m_fifo.numBits = 31;
}
} // Not got sync
else
{
// Increment the word count
// ------------------------
++m_numCode; // It got set to -1 when a sync was found, now count the 16 words
uint32_t val = m_inverted ? ~m_fifo.codeword : m_fifo.codeword;
OnDataWord(val, m_numCode);
// If at the end of a 16 word block
// --------------------------------
if (m_numCode >= 15)
{
msgCnt += OnDataFrame(m_numCode+1, (m_samplesPerSec<<10) / m_lastStableSymbolLen_1024);
m_gotSync = false;
m_numCode = -1;
}
m_fifo.numBits = 0;
}
} // If number of bits in fifo equals 32
} // While there is unread data in the bits buffer
return msgCnt;
} // extractFrames
// ====================================================================
//
// ====================================================================
short POCSAGProcessor::getBit()
{
if (m_bitsEnd != m_bitsStart)
{
if (++m_bitsEnd >= BIT_BUF_SIZE)
{
m_bitsEnd = 0;
}
return m_bits[m_bitsEnd];
}
else
{
return -1;
}
}
// ====================================================================
//
// ====================================================================
int POCSAGProcessor::getNoOfBits()
{
int bits = m_bitsEnd - m_bitsStart;
if (bits < 0) { bits += BIT_BUF_SIZE; }
return bits;
}
// ====================================================================
//
// ====================================================================
uint32_t POCSAGProcessor::getRate()
{
return ((m_samplesPerSec<<10)+512) / m_lastStableSymbolLen_1024;
}
// ====================================================================
//
// ====================================================================
int main() {
EventDispatcher event_dispatcher { std::make_unique<POCSAGProcessor>() };
event_dispatcher.run();

74
firmware/baseband/proc_pocsag.hpp
View File

@ -33,7 +33,6 @@
#include "dsp_demodulate.hpp"
#include "pocsag_packet.hpp"
#include "extract_frame_pager.hpp"
#include "pocsag.hpp"
#include "message.hpp"
@ -41,8 +40,11 @@
#include "portapack_shared_memory.hpp"
#include <cstdint>
#include <bitset>
using namespace std;
// Class used to smooth demodulated waveform prior to decoding
// -----------------------------------------------------------
template <class ValType, class CalcType>
class SmoothVals
{
@ -121,14 +123,15 @@ public:
// --------------------------------------------------
// Class to process base band data to pocsag frames
// --------------------------------------------------
class POCSAGProcessor : public BasebandProcessor, extract_frame_pager {
class POCSAGProcessor : public BasebandProcessor{
public:
void execute(const buffer_c8_t& buffer) override;
void on_message(const Message* const message) override;
virtual int OnDataFrame(int len, int baud);
virtual int OnDataWord(uint32_t word, int pos);
int OnDataFrame(int len, int baud);
int OnDataWord(uint32_t word, int pos);
private:
static constexpr size_t baseband_fs = 3072000;
@ -157,8 +160,65 @@ private:
bool configured = false;
pocsag::POCSAGPacket packet { };
void configure(const POCSAGConfigureMessage& message);
void configure();
// ----------------------------------------
// Frame extractraction methods and members
// ----------------------------------------
private:
void initFrameExtraction();
struct FIFOStruct {
unsigned long codeword;
int numBits;
};
#define BIT_BUF_SIZE (64)
void resetVals();
void setFrameExtractParams(long a_samplesPerSec, long a_maxBaud = 8000, long a_minBaud = 200, long maxRunOfSameValue = 32);
int processDemodulatedSamples(float * sampleBuff, int noOfSamples);
int extractFrames();
void storeBit();
short getBit();
int getNoOfBits();
uint32_t getRate();
uint32_t m_averageSymbolLen_1024{0};
uint32_t m_lastStableSymbolLen_1024{0};
uint32_t m_samplesPerSec{0};
uint32_t m_goodTransitions{0};
uint32_t m_badTransitions{0};
uint32_t m_sampleNo{0};
float m_sample{0};
float m_valMid{0.0f};
float m_lastSample{0.0f};
uint32_t m_lastTransPos_1024{0};
uint32_t m_lastSingleBitPos_1024{0};
uint32_t m_nextBitPosInt{0}; // Integer rounded up version to save on ops
uint32_t m_nextBitPos_1024{0};
uint32_t m_lastBitPos_1024{0};
uint32_t m_shortestGoodTrans_1024{0};
uint32_t m_minSymSamples_1024{0};
uint32_t m_maxSymSamples_1024{0};
uint32_t m_maxRunOfSameValue{0};
bitset<(size_t)BIT_BUF_SIZE> m_bits{0};
long m_bitsStart{0};
long m_bitsEnd{0};
FIFOStruct m_fifo{0,0};
bool m_gotSync{false};
int m_numCode{0};
bool m_inverted{false};
};