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MMDVM
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Adding DC estimator filter for all modes

boxcar
Andy CA6JAU 2017-07-06 00:51:46 -04:00
parent 6c4496e034
commit f8d767913e
11 changed files with 42 additions and 34 deletions
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2
DMRDMORX.cpp
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@ -88,7 +88,7 @@ bool CDMRDMORX::processSample(q15_t sample, uint16_t rssi)
m_rssi[m_dataPtr] = rssi;
m_bitBuffer[m_bitPtr] <<= 1;
if (sample < 0)
if (sample < m_dc_level)
m_bitBuffer[m_bitPtr] |= 0x01U;
if (m_state == DMORXS_NONE) {

2
DMRSlotRX.cpp
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@ -104,7 +104,7 @@ bool CDMRSlotRX::processSample(q15_t sample, uint16_t rssi)
m_rssi[m_dataPtr] = rssi;
m_bitBuffer[m_bitPtr] <<= 1;
if (sample < 0)
if (sample < m_dc_level)
m_bitBuffer[m_bitPtr] |= 0x01U;
if (m_state == DMRRXS_NONE) {

30
DStarRX.cpp
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@ -34,10 +34,6 @@ const unsigned int SYNC_POS = 21U * DSTAR_DATA_LENGTH_BITS;
const unsigned int SYNC_SCAN_START = SYNC_POS - 3U;
const unsigned int SYNC_SCAN_END = SYNC_POS + 3U;
// Generated using [b, a] = butter(1, 0.001) in MATLAB
static q31_t DC_FILTER[] = {3367972, 0, 3367972, 0, 2140747704, 0}; // {b0, 0, b1, b2, -a1, -a2}
const uint32_t DC_FILTER_STAGES = 1U; // One Biquad stage
// D-Star bit order version of 0x55 0x55 0x6E 0x0A
const uint32_t FRAME_SYNC_DATA = 0x00557650U;
const uint32_t FRAME_SYNC_MASK = 0x00FFFFFFU;
@ -261,16 +257,8 @@ m_pathMemory2(),
m_pathMemory3(),
m_fecOutput(),
m_rssiAccum(0U),
m_rssiCount(0U),
m_dcFilter(),
m_dcState()
m_rssiCount(0U)
{
::memset(m_dcState, 0x00U, 4U * sizeof(q31_t));
m_dcFilter.numStages = DC_FILTER_STAGES;
m_dcFilter.pState = m_dcState;
m_dcFilter.pCoeffs = DC_FILTER;
m_dcFilter.postShift = 0;
}
void CDStarRX::reset()
@ -286,24 +274,12 @@ void CDStarRX::reset()
}
void CDStarRX::samples(const q15_t* samples, const uint16_t* rssi, uint8_t length)
{
q31_t dc_level = 0;
q31_t dcVals[20];
q31_t intSamp[20];
::arm_q15_to_q31((q15_t*)samples, intSamp, length);
::arm_biquad_cascade_df1_q31(&m_dcFilter, intSamp, dcVals, length);
for (uint8_t i = 0U; i < length; i++)
dc_level += dcVals[i];
dc_level /= length;
{
for (uint16_t i = 0U; i < length; i++) {
m_rssiAccum += rssi[i];
m_rssiCount++;
bool bit = samples[i] < (q15_t) (dc_level >> 16);
bool bit = samples[i] < m_dc_level;
if (bit != m_prev) {
if (m_pll < (PLLMAX / 2U))

2
DStarRX.h
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@ -53,8 +53,6 @@ private:
uint8_t m_fecOutput[42U];
uint32_t m_rssiAccum;
uint16_t m_rssiCount;
arm_biquad_casd_df1_inst_q31 m_dcFilter;
q31_t m_dcState[4];
void processNone(bool bit);
void processHeader(bool bit);

2
Globals.h
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@ -93,6 +93,8 @@ extern bool m_duplex;
extern bool m_tx;
extern bool m_dcd;
extern q15_t m_dc_level;
extern CSerialPort serial;
extern CIO io;

28
IO.cpp
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@ -36,6 +36,10 @@ const uint16_t GAUSSIAN_0_5_FILTER_LEN = 12U;
static q15_t BOXCAR_FILTER[] = {3000, 3000, 3000, 3000, 3000, 0};
const uint16_t BOXCAR_FILTER_LEN = 6U;
// Generated using [b, a] = butter(1, 0.001) in MATLAB
static q31_t DC_FILTER[] = {3367972, 0, 3367972, 0, 2140747704, 0}; // {b0, 0, b1, b2, -a1, -a2}
const uint32_t DC_FILTER_STAGES = 1U; // One Biquad stage
const uint16_t DC_OFFSET = 2048U;
CIO::CIO() :
@ -62,11 +66,14 @@ m_detect(false),
m_adcOverflow(0U),
m_dacOverflow(0U),
m_watchdog(0U),
m_lockout(false)
m_lockout(false),
m_dcFilter(),
m_dcState()
{
::memset(m_rrcState, 0x00U, 70U * sizeof(q15_t));
::memset(m_gaussianState, 0x00U, 40U * sizeof(q15_t));
::memset(m_boxcarState, 0x00U, 30U * sizeof(q15_t));
::memset(m_dcState, 0x00U, 4U * sizeof(q31_t));
m_rrcFilter.numTaps = RRC_0_2_FILTER_LEN;
m_rrcFilter.pState = m_rrcState;
@ -79,6 +86,11 @@ m_lockout(false)
m_boxcarFilter.numTaps = BOXCAR_FILTER_LEN;
m_boxcarFilter.pState = m_boxcarState;
m_boxcarFilter.pCoeffs = BOXCAR_FILTER;
m_dcFilter.numStages = DC_FILTER_STAGES;
m_dcFilter.pState = m_dcState;
m_dcFilter.pCoeffs = DC_FILTER;
m_dcFilter.postShift = 0;
initInt();
}
@ -156,6 +168,20 @@ void CIO::process()
if (m_lockout)
return;
q31_t dc_level = 0;
q31_t dcVals[20];
q31_t intSamp[20];
::arm_q15_to_q31((q15_t*)samples, intSamp, RX_BLOCK_SIZE);
::arm_biquad_cascade_df1_q31(&m_dcFilter, intSamp, dcVals, RX_BLOCK_SIZE);
for (uint8_t i = 0U; i < RX_BLOCK_SIZE; i++)
dc_level += dcVals[i];
dc_level /= RX_BLOCK_SIZE;
m_dc_level = (q15_t) (dc_level >> 16);
if (m_modemState == STATE_IDLE) {
if (m_dstarEnable) {

2
IO.h
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@ -66,6 +66,8 @@ private:
q15_t m_rrcState[70U]; // NoTaps + BlockSize - 1, 42 + 20 - 1 plus some spare
q15_t m_gaussianState[40U]; // NoTaps + BlockSize - 1, 12 + 20 - 1 plus some spare
q15_t m_boxcarState[30U]; // NoTaps + BlockSize - 1, 6 + 20 - 1 plus some spare
arm_biquad_casd_df1_inst_q31 m_dcFilter;
q31_t m_dcState[4];
bool m_pttInvert;
q15_t m_rxLevel;

2
MMDVM.cpp
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@ -36,6 +36,8 @@ bool m_duplex = true;
bool m_tx = false;
bool m_dcd = false;
q15_t m_dc_level = 0;
CDStarRX dstarRX;
CDStarTX dstarTX;

2
MMDVM.ino
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@ -33,6 +33,8 @@ bool m_duplex = true;
bool m_tx = false;
bool m_dcd = false;
q15_t m_dc_level = 0;
CDStarRX dstarRX;
CDStarTX dstarTX;

2
P25RX.cpp
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@ -95,7 +95,7 @@ void CP25RX::samples(const q15_t* samples, uint16_t* rssi, uint8_t length)
m_rssiCount++;
m_bitBuffer[m_bitPtr] <<= 1;
if (sample < 0)
if (sample < m_dc_level)
m_bitBuffer[m_bitPtr] |= 0x01U;
m_buffer[m_dataPtr] = sample;

2
YSFRX.cpp
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@ -91,7 +91,7 @@ void CYSFRX::samples(const q15_t* samples, uint16_t* rssi, uint8_t length)
m_rssiCount++;
m_bitBuffer[m_bitPtr] <<= 1;
if (sample < 0)
if (sample < m_dc_level)
m_bitBuffer[m_bitPtr] |= 0x01U;
m_buffer[m_dataPtr] = sample;