Merge pull request #362 from n0mjs710/link-audio-fidelity

FM link-mode network audio: anti-alias/reconstruction filtering
Copy-construct the ds/us filters from m_filterStage1/2/3
2026-10-15 16:24:11 +02:00 · 2026-08-16 17:36:20 +01:00 · 2026-08-13 13:52:06 -05:00 · 2026-08-12 07:43:23 -05:00 · 2026-08-11 09:57:47 -05:00 · 2026-08-11 15:02:32 +01:00
43 changed files with 208 additions and 3160 deletions
@@ -1,3 +1,5 @@
+.pio
+.vscode
 *.o
 obj/
 bin/
@@ -1,36 +0,0 @@
-/*
- *   Copyright (C) 2020 by Jonathan Naylor G4KLX
- *
- *   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.
- */
-
-#if !defined(AX25DEFINES_H)
-#define  AX25DEFINES_H
-
-const uint8_t AX25_RADIO_SYMBOL_LENGTH = 20U;      // At 24 kHz sample rate
-
-const uint8_t AX25_FRAME_START = 0x7EU;
-const uint8_t AX25_FRAME_END   = 0x7EU;
-const uint8_t AX25_FRAME_ABORT = 0xFEU;
-
-const uint8_t AX25_MAX_ONES    = 5U;
-
-const uint16_t AX25_MIN_FRAME_LENGTH = 17U;        // Callsign (7) + Callsign (7) + Control (1) + Checksum (2)
-
-const uint16_t AX25_MAX_FRAME_LENGTH = 330U;       // Callsign (7) + Callsign (7) + 8 Digipeaters (56) +
-                                                   // Control (1) + PID (1) + Data (256) + Checksum (2)
-
-#endif
-
@@ -1,340 +0,0 @@
-/*
- *   Copyright (C) 2020,2023 by Jonathan Naylor G4KLX
- *   Copyright 2015-2019 Mobilinkd LLC <[email protected]>
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#include "Globals.h"
-#include "AX25Demodulator.h"
-#include "AX25Defines.h"
-
-const float32_t SAMPLE_RATE = 24000.0F;
-const float32_t SYMBOL_RATE = 1200.0F;
-
-const uint16_t DELAY_LEN = 11U;
-
-const float32_t SAMPLES_PER_SYMBOL = SAMPLE_RATE / SYMBOL_RATE;
-const float32_t PLL_LIMIT          = SAMPLES_PER_SYMBOL / 2.0F;
-
-const uint32_t LPF_FILTER_LEN = 48U;
-
-q15_t LPF_FILTER_COEFFS[] = {
-    -2,   -8,  -17,  -28,  -40,  -47,  -47,  -34,
-    -5,   46,  122,  224,  354,  510,  689,  885,
-  1092, 1302, 1506, 1693, 1856, 1987, 2077, 2124,
-  2124, 2077, 1987, 1856, 1693, 1506, 1302, 1092,
-  885,  689,  510,  354,  224,  122,   46,    -5,
-  -34,  -47,  -47,  -40,  -28,  -17,   -8,    -2
-};
-
-// Lock low-pass filter taps (80Hz Bessel)
-// scipy.signal:
-//      b, a = bessel(4, [80.0/(1200/2)], 'lowpass')
-//
-const uint8_t PLL_IIR_SIZE = 5U;
-
-const float32_t PLL_LOCK_B[] = {
-    1.077063e-03,4.308253e-03,6.462379e-03,4.308253e-03,1.077063e-03};
-
-const float32_t PLL_LOCK_A[] = {
-    1.000000e+00,-2.774567e+00,2.962960e+00,-1.437990e+00,2.668296e-01};
-
-// 64 Hz loop filter.
-// scipy.signal:
-//      loop_coeffs = firwin(9, [64.0/(1200/2)], width = None,
-//          pass_zero = True, scale = True, window='hann')
-//
-const uint32_t PLL_FILTER_LEN = 7U;
-
-float32_t PLL_FILTER_COEFFS[] = {3.196252e-02F, 1.204223e-01F, 2.176819e-01F, 2.598666e-01F, 2.176819e-01F, 1.204223e-01F, 3.196252e-02F};
-
-CAX25Demodulator::CAX25Demodulator(int8_t n) :
-m_frame(),
-m_twist(n),
-m_lpfFilter(),
-m_lpfState(),
-m_delayLine(NULL),
-m_delayPos(0U),
-m_nrziState(false),
-m_pllFilter(),
-m_pllState(),
-m_pllLast(false),
-m_pllBits(1U),
-m_pllCount(0.0F),
-m_pllJitter(0.0F),
-m_pllDCD(false),
-m_iirHistory(),
-m_hdlcOnes(0U),
-m_hdlcFlag(false),
-m_hdlcBuffer(0U),
-m_hdlcBits(0U),
-m_hdlcState(AX25_IDLE),
-m_rssiAccum(0U),
-m_rssiCount(0U)
-{
-  m_delayLine = new bool[DELAY_LEN];
-
-  m_lpfFilter.numTaps = LPF_FILTER_LEN;
-  m_lpfFilter.pState  = m_lpfState;
-  m_lpfFilter.pCoeffs = LPF_FILTER_COEFFS;
-
-  m_pllFilter.numTaps = PLL_FILTER_LEN;
-  m_pllFilter.pState  = m_pllState;
-  m_pllFilter.pCoeffs = PLL_FILTER_COEFFS;
-
-  for (uint8_t i = 0U; i < PLL_IIR_SIZE; i++)
-    m_iirHistory[i] = 0.0F;
-}
-
-bool CAX25Demodulator::process(q15_t* samples, const uint16_t* rssi, uint8_t length, CAX25Frame& frame)
-{
-  bool result = false;
-
-  q15_t fa[RX_BLOCK_SIZE];
-  m_twist.process(samples, fa, RX_BLOCK_SIZE);
-
-  int16_t buffer[RX_BLOCK_SIZE];
-  for (uint8_t i = 0; i < length; i++) {
-      bool   level = (fa[i] >= 0);
-      bool delayed = delay(level);
-      buffer[i] = (int16_t(level ^ delayed) << 1) - 1;
-  }
-
-  q15_t fc[RX_BLOCK_SIZE];
-  ::arm_fir_fast_q15(&m_lpfFilter, buffer, fc, RX_BLOCK_SIZE);
-
-  for (uint8_t i = 0; i < length; i++) {
-    m_rssiAccum += rssi[i];
-    m_rssiCount++;
-
-    bool bit = fc[i] >= 0;
-    bool sample = PLL(bit);
-
-    if (sample) {
-      // We will only ever get one frame because there are
-      // not enough bits in a block for more than one.
-      if (result) {
-        HDLC(NRZI(bit));
-      } else {
-        result = HDLC(NRZI(bit));
-        if (result) {
-          // Copy the frame data.
-          ::memcpy(frame.m_data, m_frame.m_data, AX25_MAX_PACKET_LEN);
-          frame.m_length = m_frame.m_length;
-          frame.m_fcs    = m_frame.m_fcs;
-          m_frame.m_length = 0U;
-        }
-      }
-    }
-  }
-
-  return result;
-}
-
-bool CAX25Demodulator::delay(bool b)
-{
-  bool r = m_delayLine[m_delayPos];
-
-  m_delayLine[m_delayPos++] = b;
-
-  if (m_delayPos >= DELAY_LEN)
-    m_delayPos = 0U;
-
-  return r;
-}
-
-bool CAX25Demodulator::NRZI(bool b)
-{
-  bool result = (b == m_nrziState);
-
-  m_nrziState = b;
-
-  return result;
-}
-
-bool CAX25Demodulator::PLL(bool input)
-{
-  bool sample = false;
-		
-  if (input != m_pllLast || m_pllBits > 16U) {
-    // Record transition.
-    m_pllLast = input;
-
-    if (m_pllCount > PLL_LIMIT)
-      m_pllCount -= SAMPLES_PER_SYMBOL;
-
-    float32_t adjust = m_pllBits > 16U ? 5.0F : 0.0F;
-    float32_t offset = m_pllCount / float32_t(m_pllBits);
-    float32_t jitter;
-    ::arm_fir_f32(&m_pllFilter, &offset, &jitter, 1U);
-
-    float32_t absOffset = adjust;
-    if (offset < 0.0F)
-      absOffset -= offset;
-    else
-      absOffset += offset;
-    m_pllJitter = iir(absOffset);
-
-    m_pllCount -= jitter / 2.0F;
-    m_pllBits = 1U;
-  } else {
-    if (m_pllCount > PLL_LIMIT) {
-      sample = true;
-      m_pllCount -= SAMPLES_PER_SYMBOL;
-      m_pllBits++;
-    }
-  }
-
-  m_pllCount += 1.0F;
-
-  return sample;
-}
-
-bool CAX25Demodulator::HDLC(bool b)
-{
-  if (m_hdlcOnes == AX25_MAX_ONES) {
-    if (b) {
-      // flag byte
-      m_hdlcFlag = true;
-    } else {
-      // bit stuffing...
-      m_hdlcFlag = false;
-      m_hdlcOnes = 0U;
-      return false;
-    }
-  }
-
-  m_hdlcBuffer >>= 1;
-  m_hdlcBuffer |= b ? 128U : 0U;
-  m_hdlcBits++;                      // Free-running until Sync byte.
-
-  if (b)
-    m_hdlcOnes++;
-  else
-    m_hdlcOnes = 0U;
-
-  if (m_hdlcFlag) {
-    bool result = false;
-
-    switch (m_hdlcBuffer) {
-      case AX25_FRAME_END:
-        if (m_frame.m_length >= AX25_MIN_FRAME_LENGTH) {
-          result = m_frame.checkCRC();
-          if (!result)
-              m_frame.m_length = 0U;
-        } else {
-            m_frame.m_length = 0U;
-        }
-        m_hdlcState = AX25_SYNC;
-        m_hdlcFlag = false;
-        m_hdlcBits = 0U;
-        break;
-
-      case AX25_FRAME_ABORT:
-        // Frame aborted
-        m_frame.m_length = 0U;
-        m_hdlcState = AX25_IDLE;
-        m_hdlcFlag = false;
-        m_hdlcBits = 0U;
-        break;
-
-      default:
-        break;
-    }
-
-    return result;
-  }
-
-  switch (m_hdlcState) {
-    case AX25_IDLE:
-      break;
-
-    case AX25_SYNC:
-      if (m_hdlcBits == 8U) {    // 8th bit.
-        // Start of frame data.
-        m_hdlcState = AX25_RECEIVE;
-        m_frame.append(m_hdlcBuffer);
-        m_rssiAccum = 0U;
-        m_rssiCount = 0U;
-        m_hdlcBits = 0U;
-      }
-      break;
-
-    case AX25_RECEIVE:
-      if (m_hdlcBits == 8U) {    // 8th bit.
-        m_frame.append(m_hdlcBuffer);
-        m_hdlcBits = 0U;
-      }
-      break;
-
-    default:
-      break;
-  }
-
-  return false;
-}
-
-void CAX25Demodulator::setTwist(int8_t n)
-{
-  m_twist.setTwist(n);
-}
-
-bool CAX25Demodulator::isDCD()
-{
-  if (m_pllJitter <= (SAMPLES_PER_SYMBOL * 0.03F))
-    m_pllDCD = true;
-  else if (m_pllJitter >= (SAMPLES_PER_SYMBOL * 0.15F))
-    m_pllDCD = false;
-
-  return m_pllDCD;
-}
-
-float32_t CAX25Demodulator::iir(float32_t input)
-{
-  for (int8_t i = int8_t(PLL_IIR_SIZE) - 1; i != 0; i--)
-    m_iirHistory[i] = m_iirHistory[i - 1];
-
-  m_iirHistory[0] = input;
-  for (uint8_t i = 1U; i < PLL_IIR_SIZE; i++)
-    m_iirHistory[0] -= PLL_LOCK_A[i] * m_iirHistory[i];
-
-  float32_t result = 0.0F;
-  for (uint8_t i = 0U; i < PLL_IIR_SIZE; i++)
-    result += PLL_LOCK_B[i] * m_iirHistory[i];
-
-  return result;
-}
-
-uint16_t CAX25Demodulator::getRSSI()
-{
-  if (m_rssiCount > 0U) {
-    uint16_t rssi = m_rssiAccum / m_rssiCount;
-
-    m_rssiAccum = 0U;
-    m_rssiCount = 0U;
-
-    return rssi;
-  }
-
-  return 0U;
-}
-
-#endif
-
@@ -1,81 +0,0 @@
-/*
- *   Copyright (C) 2020,2023 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#if !defined(AX25Demodulator_H)
-#define  AX25Demodulator_H
-
-#include "AX25Frame.h"
-#include "AX25Twist.h"
-
-enum AX25_STATE {
-  AX25_IDLE,
-  AX25_SYNC,
-  AX25_RECEIVE
-};
-
-class CAX25Demodulator {
-public:
-  CAX25Demodulator(int8_t n);
-
-  bool process(q15_t* samples, const uint16_t* rssi, uint8_t length, CAX25Frame& frame);
-
-  void setTwist(int8_t n);
-
-  bool isDCD();
-
-  uint16_t getRSSI();
-
-private:
-  CAX25Frame           m_frame;
-  CAX25Twist           m_twist;
-  arm_fir_instance_q15 m_lpfFilter;
-  q15_t                m_lpfState[70U];     // NoTaps + BlockSize - 1, 48 + 20 - 1 plus some spare
-  bool*                m_delayLine;
-  uint16_t             m_delayPos;
-  bool                 m_nrziState;
-  arm_fir_instance_f32 m_pllFilter;
-  float32_t            m_pllState[20U];     // NoTaps + BlockSize - 1, 7 + 1 - 1 plus some spare
-  bool                 m_pllLast;
-  uint8_t              m_pllBits;
-  float32_t            m_pllCount;
-  float32_t            m_pllJitter;
-  bool                 m_pllDCD;
-  float32_t            m_iirHistory[5U];
-  uint16_t             m_hdlcOnes;
-  bool                 m_hdlcFlag;
-  uint16_t             m_hdlcBuffer;
-  uint16_t             m_hdlcBits;
-  AX25_STATE           m_hdlcState;
-  uint32_t             m_rssiAccum;
-  uint16_t             m_rssiCount;
-
-  bool delay(bool b);
-  bool NRZI(bool b);
-  bool PLL(bool b);
-  bool HDLC(bool b);
-  float32_t iir(float32_t input);
-};
-
-#endif
-
-#endif
-
@@ -1,127 +0,0 @@
-/*
- *   Copyright (C) 2020 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#include "Globals.h"
-#include "AX25Frame.h"
-
-const uint16_t CCITT_TABLE[] = {
-	0x0000,0x1189,0x2312,0x329b,0x4624,0x57ad,0x6536,0x74bf,
-	0x8c48,0x9dc1,0xaf5a,0xbed3,0xca6c,0xdbe5,0xe97e,0xf8f7,
-	0x1081,0x0108,0x3393,0x221a,0x56a5,0x472c,0x75b7,0x643e,
-	0x9cc9,0x8d40,0xbfdb,0xae52,0xdaed,0xcb64,0xf9ff,0xe876,
-	0x2102,0x308b,0x0210,0x1399,0x6726,0x76af,0x4434,0x55bd,
-	0xad4a,0xbcc3,0x8e58,0x9fd1,0xeb6e,0xfae7,0xc87c,0xd9f5,
-	0x3183,0x200a,0x1291,0x0318,0x77a7,0x662e,0x54b5,0x453c,
-	0xbdcb,0xac42,0x9ed9,0x8f50,0xfbef,0xea66,0xd8fd,0xc974,
-	0x4204,0x538d,0x6116,0x709f,0x0420,0x15a9,0x2732,0x36bb,
-	0xce4c,0xdfc5,0xed5e,0xfcd7,0x8868,0x99e1,0xab7a,0xbaf3,
-	0x5285,0x430c,0x7197,0x601e,0x14a1,0x0528,0x37b3,0x263a,
-	0xdecd,0xcf44,0xfddf,0xec56,0x98e9,0x8960,0xbbfb,0xaa72,
-	0x6306,0x728f,0x4014,0x519d,0x2522,0x34ab,0x0630,0x17b9,
-	0xef4e,0xfec7,0xcc5c,0xddd5,0xa96a,0xb8e3,0x8a78,0x9bf1,
-	0x7387,0x620e,0x5095,0x411c,0x35a3,0x242a,0x16b1,0x0738,
-	0xffcf,0xee46,0xdcdd,0xcd54,0xb9eb,0xa862,0x9af9,0x8b70,
-	0x8408,0x9581,0xa71a,0xb693,0xc22c,0xd3a5,0xe13e,0xf0b7,
-	0x0840,0x19c9,0x2b52,0x3adb,0x4e64,0x5fed,0x6d76,0x7cff,
-	0x9489,0x8500,0xb79b,0xa612,0xd2ad,0xc324,0xf1bf,0xe036,
-	0x18c1,0x0948,0x3bd3,0x2a5a,0x5ee5,0x4f6c,0x7df7,0x6c7e,
-	0xa50a,0xb483,0x8618,0x9791,0xe32e,0xf2a7,0xc03c,0xd1b5,
-	0x2942,0x38cb,0x0a50,0x1bd9,0x6f66,0x7eef,0x4c74,0x5dfd,
-	0xb58b,0xa402,0x9699,0x8710,0xf3af,0xe226,0xd0bd,0xc134,
-	0x39c3,0x284a,0x1ad1,0x0b58,0x7fe7,0x6e6e,0x5cf5,0x4d7c,
-	0xc60c,0xd785,0xe51e,0xf497,0x8028,0x91a1,0xa33a,0xb2b3,
-	0x4a44,0x5bcd,0x6956,0x78df,0x0c60,0x1de9,0x2f72,0x3efb,
-	0xd68d,0xc704,0xf59f,0xe416,0x90a9,0x8120,0xb3bb,0xa232,
-	0x5ac5,0x4b4c,0x79d7,0x685e,0x1ce1,0x0d68,0x3ff3,0x2e7a,
-	0xe70e,0xf687,0xc41c,0xd595,0xa12a,0xb0a3,0x8238,0x93b1,
-	0x6b46,0x7acf,0x4854,0x59dd,0x2d62,0x3ceb,0x0e70,0x1ff9,
-	0xf78f,0xe606,0xd49d,0xc514,0xb1ab,0xa022,0x92b9,0x8330,
-	0x7bc7,0x6a4e,0x58d5,0x495c,0x3de3,0x2c6a,0x1ef1,0x0f78 };
-
-CAX25Frame::CAX25Frame(const uint8_t* data, uint16_t length) :
-m_data(),
-m_length(0U),
-m_fcs(0U)
-{
-  for (uint16_t i = 0U; i < length && i < (AX25_MAX_PACKET_LEN - 2U); i++)
-    m_data[m_length++] = data[i];
-}
-
-CAX25Frame::CAX25Frame() :
-m_data(),
-m_length(0U),
-m_fcs(0U)
-{
-}
-
-bool CAX25Frame::append(uint16_t c)
-{
-  if (m_length == AX25_MAX_PACKET_LEN)
-    return false;
-
-  m_data[m_length++] = uint8_t(c);
-
-  return true;
-}
-
-bool CAX25Frame::checkCRC()
-{
-  union {
-    uint16_t crc16;
-    uint8_t  crc8[2U];
-  };
-
-  crc16 = 0xFFFFU;
-  for (uint16_t i = 0U; i < (m_length - 2U); i++)
-    crc16 = uint16_t(crc8[1U]) ^ CCITT_TABLE[crc8[0U] ^ m_data[i]];
-
-  crc16 = ~crc16;
-
-  if (crc8[0U] == m_data[m_length - 2U] && crc8[1U] == m_data[m_length - 1U]) {
-    m_fcs = crc16;
-    return true;
-  } else {
-    return false;
-  }
-}
-
-void CAX25Frame::addCRC()
-{
-  union {
-    uint16_t crc16;
-    uint8_t  crc8[2U];
-  };
-
-  crc16 = 0xFFFFU;
-  for (uint16_t i = 0U; i < m_length; i++)
-    crc16 = uint16_t(crc8[1U]) ^ CCITT_TABLE[crc8[0U] ^ m_data[i]];
-
-  crc16 = ~crc16;
-
-  m_fcs = crc16;
-
-  m_data[m_length++] = crc8[0U];
-  m_data[m_length++] = crc8[1U];
-}
-
-#endif
-
@@ -1,47 +0,0 @@
-/*
- *   Copyright (C) 2020 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#if !defined(AX25Frame_H)
-#define  AX25Frame_H
-
-const uint16_t AX25_MAX_PACKET_LEN = 300U;
-
-class CAX25Frame {
-public:
-  CAX25Frame(const uint8_t* data, uint16_t length);
-  CAX25Frame();
-
-  bool append(uint16_t c);
-
-  bool checkCRC();
-
-  void addCRC();
-
-  uint8_t  m_data[AX25_MAX_PACKET_LEN];
-  uint16_t m_length;
-  uint16_t m_fcs;
-};
-
-#endif
-
-#endif
-
@@ -1,235 +0,0 @@
-/*
- *   Copyright (C) 2020,2023 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#include "Globals.h"
-#include "AX25RX.h"
-
-/*
- * Generated with Scipy Filter, 152 coefficients, 1100-2300Hz bandpass,
- * Hann window, starting and ending 0 value coefficients removed.
- *
- * np.array(
- *  firwin2(152,
- *      [
- *          0.0,
- *          1000.0/(sample_rate/2),
- *          1100.0/(sample_rate/2),
- *          2350.0/(sample_rate/2),
- *          2500.0/(sample_rate/2),
- *          1.0
- *      ],
- *      [0,0,1,1,0,0],
- *      antisymmetric = False,
- *      window='hann') * 32768,
- *  dtype=int)[10:-10]
- */
-
-const uint32_t FILTER_LEN = 130U;
-
-q15_t FILTER_COEFFS[] = {
-      5,    12,    18,    21,   19,   11,    -2,   -15,   -25,   -27,
-    -21,   -11,    -3,    -5,  -19,  -43,   -69,   -83,   -73,   -35,
-     27,    98,   155,   180,  163,  109,    39,   -20,   -45,   -26,
-     23,    74,    89,    39,  -81, -247,  -407,  -501,  -480,  -334,
-    -92,   175,   388,   479,  429,  275,    99,     5,    68,   298,
-    626,   913,   994,   740,  115, -791, -1770, -2544, -2847, -2509,
-  -1527,   -76,  1518,  2875, 3653, 3653,  2875,  1518,   -76, -1527,
-  -2509, -2847, -2544, -1770, -791,  115,   740,   994,   913,   626,
-    298,    68,     5,    99,  275,  429,   479,   388,   175,   -92,
-   -334,  -480,  -501,  -407, -247,  -81,    39,    89,    74,    23,
-    -26,   -45,   -20,    39,  109,  163,   180,   155,    98,    27,
-    -35,   -73,   -83,   -69,  -43,  -19,    -5,    -3,   -11,   -21,
-    -27,   -25,   -15,    -2,   11,   19,    21,    18,    12,     5
-};
-
-CAX25RX::CAX25RX() :
-m_filter(),
-m_state(),
-m_demod1(3),
-m_demod2(6),
-m_demod3(9),
-m_lastFCS(0U),
-m_count(0U),
-m_slotTime(30U),
-m_slotCount(0U),
-m_pPersist(128U),
-m_dcd(false),
-m_canTX(false),
-m_x(1U),
-m_a(0xB7U),
-m_b(0x73U),
-m_c(0xF6U)
-{
-  m_filter.numTaps = FILTER_LEN;
-  m_filter.pState  = m_state;
-  m_filter.pCoeffs = FILTER_COEFFS;
-
-  initRand();
-}
-
-void CAX25RX::samples(q15_t* samples, const uint16_t* rssi, uint8_t length)
-{
-  q15_t output[RX_BLOCK_SIZE];
-  ::arm_fir_fast_q15(&m_filter, samples, output, RX_BLOCK_SIZE);
-
-  m_count++;
-
-  CAX25Frame frame;
-
-  bool ret = m_demod1.process(output, rssi, length, frame);
-  if (ret) {
-    if (frame.m_fcs != m_lastFCS || m_count > 2U) {
-      m_lastFCS = frame.m_fcs;
-      m_count   = 0U;
-#if defined(SEND_RSSI_DATA)
-      uint16_t rssi = m_demod1.getRSSI();
-      if (rssi > 0U)
-        serial.writeAX25DataEx(rssi, frame.m_data, frame.m_length - 2U);
-      else
-        serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
-#else
-      serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
-#endif
-    }
-    DEBUG1("Decoder 1 reported");
-  }
-
-  ret = m_demod2.process(output, rssi, length, frame);
-  if (ret) {
-    if (frame.m_fcs != m_lastFCS || m_count > 2U) {
-      m_lastFCS = frame.m_fcs;
-      m_count   = 0U;
-#if defined(SEND_RSSI_DATA)
-      uint16_t rssi = m_demod2.getRSSI();
-      if (rssi > 0U)
-        serial.writeAX25DataEx(rssi, frame.m_data, frame.m_length - 2U);
-      else
-        serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
-#else
-      serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
-#endif
-    }
-    DEBUG1("Decoder 2 reported");
-  }
-
-  ret = m_demod3.process(output, rssi, length, frame);
-  if (ret) {
-    if (frame.m_fcs != m_lastFCS || m_count > 2U) {
-      m_lastFCS = frame.m_fcs;
-      m_count   = 0U;
-#if defined(SEND_RSSI_DATA)
-      uint16_t rssi = m_demod3.getRSSI();
-      if (rssi > 0U)
-        serial.writeAX25DataEx(rssi, frame.m_data, frame.m_length - 2U);
-      else
-        serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
-#else
-      serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
-#endif
-    }
-    DEBUG1("Decoder 3 reported");
-  }
-
-  m_slotCount += RX_BLOCK_SIZE;
-  if (m_slotCount >= m_slotTime) {
-    m_slotCount = 0U;
-
-    bool dcd1 = m_demod1.isDCD();
-    bool dcd2 = m_demod2.isDCD();
-    bool dcd3 = m_demod3.isDCD();
-    
-    if (dcd1 || dcd2 || dcd3) {
-      if (!m_dcd) {
-        io.setDecode(true);
-        io.setADCDetection(true);
-        m_dcd = true;
-      }
-
-      m_canTX = false;
-    } else {
-      if (m_dcd) {
-        io.setDecode(false);
-        io.setADCDetection(false);
-        m_dcd = false;
-      }
-
-      m_canTX = m_pPersist >= rand();
-    }
-  }
-}
-
-bool CAX25RX::canTX() const
-{
-  return m_canTX;
-}
-
-void CAX25RX::setParams(int8_t twist, uint8_t slotTime, uint8_t pPersist)
-{
-  m_demod1.setTwist(twist - 3);
-  m_demod2.setTwist(twist);
-  m_demod3.setTwist(twist + 3);
-
-  m_slotTime = slotTime * 240U;    // Slot time in samples
-  m_pPersist = pPersist;
-}
-
-// Taken from https://www.electro-tech-online.com/threads/ultra-fast-pseudorandom-number-generator-for-8-bit.124249/
-//X ABC Algorithm Random Number Generator for 8-Bit Devices:
-//This is a small PRNG, experimentally verified to have at least a 50 million byte period
-//by generating 50 million bytes and observing that there were no overapping sequences and repeats.
-//This generator passes serial correlation, entropy , Monte Carlo Pi value, arithmetic mean,
-//And many other statistical tests. This generator may have a period of up to 2^32, but this has
-//not been verified.
-//
-// By XORing 3 bytes into the a,b, and c registers, you can add in entropy from 
-//an external source easily.
-//
-//This generator is free to use, but is not suitable for cryptography due to its short period(by //cryptographic standards) and simple construction. No attempt was made to make this generator 
-// suitable for cryptographic use.
-//
-//Due to the use of a constant counter, the generator should be resistant to latching up.
-//A significant performance gain is had in that the x variable is only ever incremented.
-//
-//Only 4 bytes of ram are needed for the internal state, and generating a byte requires 3 XORs , //2 ADDs, one bit shift right , and one increment. Difficult or slow operations like multiply, etc 
-//were avoided for maximum speed on ultra low power devices.
-
-
-void CAX25RX::initRand() //Can also be used to seed the rng with more entropy during use.
-{
-  m_a = (m_a ^ m_c ^ m_x);
-  m_b = (m_b + m_a);
-  m_c = (m_c + (m_b >> 1) ^ m_a);
-}
-
-uint8_t CAX25RX::rand()
-{
-  m_x++;                           //x is incremented every round and is not affected by any other variable
-
-  m_a = (m_a ^ m_c ^ m_x);         //note the mix of addition and XOR
-  m_b = (m_b + m_a);               //And the use of very few instructions
-  m_c = (m_c + (m_b >> 1) ^ m_a);  //the right shift is to ensure that high-order bits from b can affect  
-
-  return uint8_t(m_c);             //low order bits of other variables
-}
-
-#endif
-
@@ -1,63 +0,0 @@
-/*
- *   Copyright (C) 2020,2023 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#if !defined(AX25RX_H)
-#define  AX25RX_H
-
-#include "AX25Demodulator.h"
-
-class CAX25RX {
-public:
-  CAX25RX();
-
-  void samples(q15_t* samples, const uint16_t* rssi, uint8_t length);
-
-  void setParams(int8_t twist, uint8_t slotTime, uint8_t pPersist);
-
-  bool canTX() const;
-
-private:
-  arm_fir_instance_q15 m_filter;
-  q15_t                m_state[160U];    // NoTaps + BlockSize - 1, 130 + 20 - 1 plus some spare
-  CAX25Demodulator     m_demod1;
-  CAX25Demodulator     m_demod2;
-  CAX25Demodulator     m_demod3;
-  uint16_t             m_lastFCS;
-  uint32_t             m_count;
-  uint32_t             m_slotTime;
-  uint32_t             m_slotCount;
-  uint8_t              m_pPersist;
-  bool                 m_dcd;
-  bool                 m_canTX;
-  uint8_t              m_x;
-  uint8_t              m_a;
-  uint8_t              m_b;
-  uint8_t              m_c;
-  
-  void initRand();
-  uint8_t rand();
-};
-
-#endif
-
-#endif
-
@@ -1,191 +0,0 @@
-/*
- *   Copyright (C) 2020 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#include "Globals.h"
-#include "AX25TX.h"
-
-#include "AX25Defines.h"
-#include "AX25Frame.h"
-
-
-const uint8_t START_FLAG[] = { AX25_FRAME_START };
-const uint8_t END_FLAG[]   = { AX25_FRAME_END };
-
-const uint8_t BIT_MASK_TABLE1[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };
-
-#define WRITE_BIT1(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE1[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE1[(i)&7])
-#define READ_BIT1(p,i)    (p[(i)>>3] & BIT_MASK_TABLE1[(i)&7])
-
-const uint8_t BIT_MASK_TABLE2[] = { 0x01U, 0x02U, 0x04U, 0x08U, 0x10U, 0x20U, 0x40U, 0x80U };
-
-#define WRITE_BIT2(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE2[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE2[(i)&7])
-#define READ_BIT2(p,i)    (p[(i)>>3] & BIT_MASK_TABLE2[(i)&7])
-
-const uint16_t AUDIO_TABLE_LEN = 120U;
-
-const q15_t AUDIO_TABLE_DATA[] = {
-  0, 214, 428, 641, 851, 1060, 1265, 1468, 1666, 1859, 2048, 2230, 2407, 2577, 2740, 2896, 3043, 3182, 3313, 3434, 3546, 3649,
-  3741, 3823, 3895, 3955, 4006, 4045, 4073, 4089, 4095, 4089, 4073, 4045, 4006, 3955, 3895, 3823, 3741, 3649, 3546, 3434, 3313,
-  3182, 3043, 2896, 2740, 2577, 2407, 2230, 2048, 1859, 1666, 1468, 1265, 1060, 851, 641, 428, 214, 0, -214, -428, -641, -851,
-  -1060, -1265, -1468, -1666, -1859, -2047, -2230, -2407, -2577, -2740, -2896, -3043, -3182, -3313, -3434, -3546, -3649, -3741,
-  -3823, -3895, -3955, -4006, -4045, -4073, -4089, -4095, -4089, -4073, -4045, -4006, -3955, -3895, -3823, -3741, -3649, -3546,
-  -3434, -3313, -3182, -3043, -2896, -2740, -2577, -2407, -2230, -2047, -1859, -1666, -1468, -1265, -1060, -851, -641, -428, -214
-};
-
-CAX25TX::CAX25TX() :
-m_poBuffer(),
-m_poLen(0U),
-m_poPtr(0U),
-m_txDelay(360U),
-m_tablePtr(0U),
-m_nrzi(false)
-{
-}
-
-void CAX25TX::process()
-{
-  if (m_poLen == 0U)
-    return;
-
-  if (!m_duplex) {
-    if (m_poPtr == 0U) {
-      bool tx = ax25RX.canTX();
-      if (!tx)
-        return;
-    }
-  }
-
-  uint16_t space = io.getSpace();
-
-  while (space > AX25_RADIO_SYMBOL_LENGTH) {
-    bool b = READ_BIT1(m_poBuffer, m_poPtr) != 0U;
-    m_poPtr++;
-
-    writeBit(b);
-
-    space -= AX25_RADIO_SYMBOL_LENGTH;
-
-    if (m_poPtr >= m_poLen) {
-      m_poPtr = 0U;
-      m_poLen = 0U;
-      return;
-    }
-  }
-}
-
-uint8_t CAX25TX::writeData(const uint8_t* data, uint16_t length)
-{
-  CAX25Frame frame(data, length);
-  frame.addCRC();
-
-  m_poLen    = 0U;
-  m_poPtr    = 0U;
-  m_nrzi     = false;
-  m_tablePtr = 0U;
-
-  // Add TX delay
-  for (uint16_t i = 0U; i < m_txDelay; i++, m_poLen++) {
-    bool preamble = NRZI(false);
-    WRITE_BIT1(m_poBuffer, m_poLen, preamble);
-  }
-
-  // Add the Start Flag
-  for (uint16_t i = 0U; i < 8U; i++, m_poLen++) {
-    bool b1 = READ_BIT1(START_FLAG, i) != 0U;
-    bool b2 = NRZI(b1);
-    WRITE_BIT1(m_poBuffer, m_poLen, b2);
-  }
-
-  uint8_t ones = 0U;
-  for (uint16_t i = 0U; i < (frame.m_length * 8U); i++) {
-    bool b1 = READ_BIT2(frame.m_data, i) != 0U;
-    bool b2 = NRZI(b1);
-    WRITE_BIT1(m_poBuffer, m_poLen, b2);
-    m_poLen++;
-
-    if (b1) {
-      ones++;
-      if (ones == AX25_MAX_ONES) {
-        // Bit stuffing
-        bool b = NRZI(false);
-        WRITE_BIT1(m_poBuffer, m_poLen, b);
-        m_poLen++;
-        ones = 0U;
-      }
-    } else {
-      ones = 0U;
-    }
-  }
-
-  // Add the End Flag
-  for (uint16_t i = 0U; i < 8U; i++, m_poLen++) {
-    bool b1 = READ_BIT1(END_FLAG, i) != 0U;
-    bool b2 = NRZI(b1);
-    WRITE_BIT1(m_poBuffer, m_poLen, b2);
-  }
-
-  return 0U;
-}
-
-void CAX25TX::writeBit(bool b)
-{
-  q15_t buffer[AX25_RADIO_SYMBOL_LENGTH];
-  for (uint8_t i = 0U; i < AX25_RADIO_SYMBOL_LENGTH; i++) {
-    q15_t value = AUDIO_TABLE_DATA[m_tablePtr];
-
-    if (b) {
-      // De-emphasise the lower frequency by 6dB
-      value >>= 2;
-      m_tablePtr += 6U;
-    } else {
-      m_tablePtr += 11U;
-    }
-
-    buffer[i] = value >> 1;
-
-    if (m_tablePtr >= AUDIO_TABLE_LEN)
-      m_tablePtr -= AUDIO_TABLE_LEN;
-  }
-
-  io.write(STATE_AX25, buffer, AX25_RADIO_SYMBOL_LENGTH);
-}
-
-void CAX25TX::setTXDelay(uint8_t delay)
-{
-  m_txDelay = delay * 12U;
-}
-
-uint8_t CAX25TX::getSpace() const
-{
-  return m_poLen == 0U ? 255U : 0U;
-}
-
-bool CAX25TX::NRZI(bool b)
-{
-    if (!b)
-      m_nrzi = !m_nrzi;
-
-    return m_nrzi;
-}
-
-#endif
-
@@ -1,53 +0,0 @@
-/*
- *   Copyright (C) 2020 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#if !defined(AX25TX_H)
-#define  AX25TX_H
-
-class CAX25TX {
-public:
-  CAX25TX();
-
-  uint8_t writeData(const uint8_t* data, uint16_t length);
-
-  void process();
-
-  void setTXDelay(uint8_t delay);
-
-  uint8_t getSpace() const;
-
-private:
-  uint8_t    m_poBuffer[600U];
-  uint16_t   m_poLen;
-  uint16_t   m_poPtr;
-  uint16_t   m_txDelay;
-  uint16_t   m_tablePtr;
-  bool       m_nrzi;
-
-  void writeBit(bool b);
-  bool NRZI(bool b);
-};
-
-#endif
-
-#endif
-
@@ -1,316 +0,0 @@
-/*
- *   Copyright (C) 2020 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#include "Globals.h"
-#include "AX25Twist.h"
-
-// 1200Hz = -12dB, 2200Hz = 0dB; 3381Hz cutoff; cosine.
-q15_t dB12[] = {
-  176,
-  -812,
-  -3916,
-  -7586,
-  23536,
-  -7586,
-  -3916,
-  -812,
-  176
-};
-
-// 1200Hz = -11dB, 2200Hz = 0dB; 3258Hz cutoff; cosine.
-q15_t dB11[] = {
-  121,
-  -957,
-  -3959,
-  -7383,
-  23871,
-  -7383,
-  -3959,
-  -957,
-  121
-};
-
-// 1200Hz = -10dB, 2200Hz = 0dB; 3118Hz cutoff; cosine.
-q15_t dB10[] = {
-  56,
-  -1110,
-  -3987,
-  -7141,
-  24254,
-  -7141,
-  -3987,
-  -1110,
-  56
-};
-
-// 1200Hz = -9dB, 2200Hz = 0dB; 2959Hz cutoff; cosine.
-q15_t dB9[] = {
-  -19,
-  -1268,
-  -3994,
-  -6856,
-  24688,
-  -6856,
-  -3994,
-  -1268,
-  -19
-};
-
-// 1200Hz = -8dB, 2200Hz = 0dB; 2778Hz cutoff; cosine.
-q15_t dB8[] = {
-  -104,
-  -1424,
-  -3968,
-  -6516,
-  25182,
-  -6516,
-  -3968,
-  -1424,
-  -104
-};
-
-// 1200Hz = -7dB, 2200Hz = 0dB; 2573Hz cutoff; cosine.
-q15_t dB7[] = {
-  -196,
-  -1565,
-  -3896,
-  -6114,
-  25742,
-  -6114,
-  -3896,
-  -1565,
-  -196
-};
-
-// 1200Hz = -6dB, 2200Hz = 0dB; 2343Hz cutoff; cosine.
-q15_t dB6[] = {
-  -288,
-  -1676,
-  -3761,
-  -5642,
-  26370,
-  -5642,
-  -3761,
-  -1676,
-  -288
-};
-
-// 1200Hz = -5dB, 2200Hz = 0dB; 2085Hz cutoff; cosine.
-q15_t dB5[] = {
-  -370,
-  -1735,
-  -3545,
-  -5088,
-  27075,
-  -5088,
-  -3545,
-  -1735,
-  -370
-};
-
-// 1200Hz = -4dB, 2200Hz = 0dB; 1790Hz cutoff; cosine.
-q15_t dB4[] = {
-  -432,
-  -1715,
-  -3220,
-  -4427,
-  27880,
-  -4427,
-  -3220,
-  -1715,
-  -432
-};
-
-// 1200Hz = -3dB, 2200Hz = 0dB; 1456Hz cutoff; cosine.
-q15_t dB3[] = {
-  -452,
-  -1582,
-  -2759,
-  -3646,
-  28792,
-  -3646,
-  -2759,
-  -1582,
-  -452
-};
-
-// 1200Hz = -2dB, 2200Hz = 0dB; 1070Hz cutoff; cosine.
-q15_t dB2[] = {
-  -408,
-  -1295,
-  -2123,
-  -2710,
-  29846,
-  -2710,
-  -2123,
-  -1295,
-  -408
-};
-
-// 1200Hz = -1dB, 2200Hz = 0dB; 605Hz cutoff; cosine.
-q15_t dB1[] = {
-  -268,
-  -795,
-  -1244,
-  -1546,
-  31116,
-  -1546,
-  -1244,
-  -795,
-  -268
-};
-
-q15_t dB0[] = {
-  0,
-  0,
-  0,
-  0,
-  32767,
-  0,
-  0,
-  0,
-  0,
-};
-
-// 1200Hz = 0dB, 2200Hz = -1dB; 4130Hz cutoff; cosine.
-q15_t dB_1[] = {
-  -419,
-  -177,
-  3316,
-  8650,
-  11278,
-  8650,
-  3316,
-  -177,
-  -419
-};
-
-// 1200Hz = 0dB, 2200Hz = -2dB; 3190Hz cutoff; cosine.
-q15_t dB_2[] = {
-  -90,
-  1033,
-  3975,
-  7267,
-  8711,
-  7267,
-  3975,
-  1033,
-  -90
-};
-
-// 1200Hz = 0dB, 2200Hz = -3dB; 2330Hz cutoff; cosine.
-q15_t dB_3[] = {
-  292,
-  1680,
-  3752,
-  5615,
-  6362,
-  5615,
-  3752,
-  1680,
-  292
-};
-
-// 1200Hz = 0dB, 2200Hz = -4dB; 2657Hz cutoff; boxcar.
-q15_t dB_4[] = {
-  917,
-  3024,
-  5131,
-  6684,
-  7255,
-  6684,
-  5131,
-  3024,
-  917
-};
-
-// 1200Hz = 0dB, 2200Hz = -5dB; 2360Hz cutoff; boxcar.
-q15_t dB_5[] = {
-  1620,
-  3339,
-  4925,
-  6042,
-  6444,
-  6042,
-  4925,
-  3339,
-  1620
-};
-
-// 1200Hz = 0dB, 2200Hz = -6dB; 2067Hz cutoff; boxcar.
-q15_t dB_6[] = {
-  2161,
-  3472,
-  4605,
-  5373,
-  5644,
-  5373,
-  4605,
-  3472,
-  2161
-};
-
-q15_t* coeffs[] = {
-  dB12,
-  dB11,
-  dB10,
-  dB9,
-  dB8,
-  dB7,
-  dB6,
-  dB5,
-  dB4,
-  dB3,
-  dB2,
-  dB1,
-  dB0,
-  dB_1,
-  dB_2,
-  dB_3,
-  dB_4,
-  dB_5,
-  dB_6
-};
-
-CAX25Twist::CAX25Twist(int8_t n) :
-m_filter(),
-m_state()
-{
-  setTwist(n);
-}
-
-void CAX25Twist::process(q15_t* in, q15_t* out, uint8_t length)
-{
-  ::arm_fir_fast_q15(&m_filter, in, out, length);
-}
-
-void CAX25Twist::setTwist(int8_t n)
-{
-  uint8_t twist = uint8_t(n + 6);
-
-  m_filter.numTaps = 9;
-  m_filter.pState  = m_state;
-  m_filter.pCoeffs = coeffs[twist];
-}
-
-#endif
-
@@ -1,42 +0,0 @@
-/*
- *   Copyright (C) 2020 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_AX25)
-
-#if !defined(AX25Twist_H)
-#define  AX25Twist_H
-
-class CAX25Twist {
-public:
-  CAX25Twist(int8_t n);
-
-  void process(q15_t* in, q15_t* out, uint8_t length);
-
-  void setTwist(int8_t n);
-
-private:
-  arm_fir_instance_q15 m_filter;
-  q15_t                m_state[40U];   // NoTaps + BlockSize - 1, 9 + 20 - 1 plus some spare
-};
-
-#endif
-
-#endif
-
@@ -1,66 +0,0 @@
-/*
- *   Copyright (C) 2009-2015,2020,2021 by Jonathan Naylor G4KLX
- *   Copyright (C) 2016 by Colin Durbridge G4EML
- *
- *   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"
-
-#if defined(MODE_M17)
-
-#include "Globals.h"
-#include "CalM17.h"
-#include "M17Defines.h"
-
-const uint8_t PREAMBLE[] = {0x00U,
-	0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U,
-	0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U,
-	0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U,
-	0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U,
-	0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U,
-	0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U, 0x77U};
-
-CCalM17::CCalM17() :
-m_transmit(false)
-{
-}
-
-void CCalM17::process()
-{
-  m17TX.process();
-
-  if (!m_transmit)
-    return;
-
-  uint16_t space = m17TX.getSpace();
-  if (space < 2U)
-    return;
-
-  m17TX.writeData(PREAMBLE, M17_FRAME_LENGTH_BYTES + 1U);
-}
-
-uint8_t CCalM17::write(const uint8_t* data, uint16_t length)
-{
-  if (length != 1U)
-    return 4U;
-
-  m_transmit = data[0U] == 1U;
-
-  return 0U;
-}
-
-#endif
-
@@ -1,43 +0,0 @@
-/*
- *   Copyright (C) 2009-2015,2020,2021 by Jonathan Naylor G4KLX
- *   Copyright (C) 2016 by Colin Durbridge G4EML
- *
- *   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"
-
-#if defined(MODE_M17)
-
-#if !defined(CALM17_H)
-#define  CALM17_H
-
-
-class CCalM17 {
-public:
-  CCalM17();
-
-  void process();
-
-  uint8_t write(const uint8_t* data, uint16_t length);
-
-private:
-  bool m_transmit;
-};
-
-#endif
-
-#endif
-
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017,2018,2020 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2018,2020,2025 by Jonathan Naylor G4KLX
 *
 *   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
@@ -38,18 +38,12 @@
 #define MODE_NXDN
 #define USE_NXDN_BOXCAR

-// Enable M17 support.
-#define MODE_M17
-
 // Enable POCSAG support.
 #define MODE_POCSAG

 // Enable FM support.
 #define MODE_FM

-// Enable AX.25 support, this is only enabled if FM is also enabled.
-#define MODE_AX25
-
 // Allow for the use of high quality external clock oscillators
 // The number is the frequency of the oscillator in Hertz.
 //
@@ -116,9 +110,6 @@
 // Use the YSF and P25 LEDs for NXDN
 // #define USE_ALTERNATE_NXDN_LEDS

-// Use the D-Star and P25 LEDs for M17
-#define USE_ALTERNATE_M17_LEDS
-
 // Use the D-Star and DMR LEDs for POCSAG
 #define USE_ALTERNATE_POCSAG_LEDS

@@ -2,6 +2,7 @@
 *   Copyright (C) 2009-2017,2020 by Jonathan Naylor G4KLX
 *   Copyright (C) 2016 by Colin Durbridge G4EML
 *   Copyright (C) 2017 by Andy Uribe CA6JAU
+ *   Copyright (C) 2022,2023,2026 by Adrian Musceac YO8RZZ
 *
 *   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
@@ -42,6 +43,12 @@ const uint8_t IDLE_DATA[] =
         0x36U, 0x00U, 0x0DU, 0xFFU, 0x57U, 0xD7U, 0x5DU, 0xF5U, 0xD0U, 0x03U, 0xF6U,
         0xE4U, 0x65U, 0x17U, 0x1BU, 0x48U, 0xCAU, 0x6DU, 0x4FU, 0xC6U, 0x10U, 0xB4U};

+// DT Terminator with LC, empty
+const uint8_t TERMINATOR_DATA[] =
+        {0x00U, 0xCCU, 0x01U, 0x80U, 0x01U, 0x94U, 0x01U, 0x48U, 0x08U, 0xB0U, 0x08U,
+         0x80U, 0x04U, 0xADU, 0xFFU, 0x57U, 0xD7U, 0x5DU, 0xF5U, 0xD9U, 0x65U, 0x90U,
+         0x01U, 0x78U, 0x00U, 0xD0U, 0x08U, 0x40U, 0x14U, 0x00U, 0x0DU, 0x80U, 0x15U};
+
 const uint8_t CACH_INTERLEAVE[] =
        { 1U,  2U,  3U,  5U,  6U,  7U,  9U, 10U, 11U, 13U, 15U, 16U, 17U, 19U, 20U, 21U, 23U,
         25U, 26U, 27U, 29U, 30U, 31U, 33U, 34U, 35U, 37U, 39U, 40U, 41U, 43U, 44U, 45U, 47U,
@@ -65,6 +72,7 @@ m_modFilter(),
 m_modState(),
 m_state(DMRTXSTATE_IDLE),
 m_idle(),
+m_aloha(),
 m_cachPtr(0U),
 m_shortLC(),
 m_newShortLC(),
@@ -74,7 +82,10 @@ m_poLen(0U),
 m_poPtr(0U),
 m_frameCount(0U),
 m_abortCount(),
-m_abort()
+m_abort(),
+m_controlChannel(false),
+m_trunking(false),
+m_colorCode(0U)
 {
  ::memset(m_modState, 0x00U, 16U * sizeof(q15_t));

@@ -211,6 +222,23 @@ uint8_t CDMRTX::writeShortLC(const uint8_t* data, uint16_t length)
  return 0U;
 }

+uint8_t CDMRTX::writeAloha(const uint8_t* data, uint16_t length)
+{
+  if (length != DMR_FRAME_LENGTH_BYTES)
+    return 4U;
+
+  ::memcpy(m_aloha, data, length);
+
+  // Stamp the slot type with the current colour code so that the result
+  // doesn't depend on the ordering of the ALOHA and SET_CONFIG commands.
+  CDMRSlotType slotType;
+  slotType.encode(m_colorCode, DT_CSBK, m_aloha);
+
+  m_controlChannel = true;
+
+  return 0U;
+}
+
 uint8_t CDMRTX::writeAbort(const uint8_t* data, uint16_t length)
 {
  if (length != 1U)
@@ -294,7 +322,7 @@ uint8_t CDMRTX::getSpace2() const

 void CDMRTX::createData(uint8_t slotIndex)
 {
-  if (m_fifo[slotIndex].getData() >= DMR_FRAME_LENGTH_BYTES && m_frameCount >= STARTUP_COUNT && m_abortCount[slotIndex] >= ABORT_COUNT) {
+  if ((m_fifo[slotIndex].getData() >= DMR_FRAME_LENGTH_BYTES) && (m_frameCount >= STARTUP_COUNT) && (m_abortCount[slotIndex] >= ABORT_COUNT)) {
    for (unsigned int i = 0U; i < DMR_FRAME_LENGTH_BYTES; i++) {
      m_fifo[slotIndex].get(m_poBuffer[i]);
      m_markBuffer[i] = MARK_NONE;
@@ -303,7 +331,11 @@ void CDMRTX::createData(uint8_t slotIndex)
    m_abort[slotIndex] = false;
    // Transmit an idle message
    for (unsigned int i = 0U; i < DMR_FRAME_LENGTH_BYTES; i++) {
-      m_poBuffer[i]   = m_idle[i];
+      if ((slotIndex == 0U) && m_controlChannel && m_trunking)
+        m_poBuffer[i] = m_aloha[i];
+      else
+        m_poBuffer[i] = m_idle[i];
+
      m_markBuffer[i] = MARK_NONE;
    }
  }
@@ -354,10 +386,14 @@ void CDMRTX::createCACH(uint8_t txSlotIndex, uint8_t rxSlotIndex)
    m_cachPtr = 0U;

  if (m_cachPtr == 0U) {
-    if (m_fifo[0U].getData() == 0U && m_fifo[1U].getData() == 0U)
-      ::memcpy(m_shortLC, EMPTY_SHORT_LC, 12U);
-    else
+    if ((m_fifo[0U].getData() == 0U) && (m_fifo[1U].getData() == 0U)) {
+      if (m_trunking)
+        ::memcpy(m_shortLC, m_newShortLC, 12U);
+      else
+        ::memcpy(m_shortLC, EMPTY_SHORT_LC, 12U);
+    } else {
      ::memcpy(m_shortLC, m_newShortLC, 12U);
+    }
  }

  ::memcpy(m_poBuffer, m_shortLC + m_cachPtr, 3U);
@@ -367,8 +403,8 @@ void CDMRTX::createCACH(uint8_t txSlotIndex, uint8_t rxSlotIndex)

  bool at = false;
  if (m_frameCount >= STARTUP_COUNT)
-    at = m_fifo[rxSlotIndex].getData() > 0U;
-  bool tc = txSlotIndex == 1U;
+    at = (m_fifo[rxSlotIndex].getData() > 0U);
+  bool tc  = (txSlotIndex == 1U);
  bool ls0 = true;            // For 1 and 2
  bool ls1 = true;

@@ -397,10 +433,20 @@ void CDMRTX::createCACH(uint8_t txSlotIndex, uint8_t rxSlotIndex)

 void CDMRTX::setColorCode(uint8_t colorCode)
 {
-  ::memcpy(m_idle, IDLE_DATA, DMR_FRAME_LENGTH_BYTES);
+  m_colorCode = colorCode;
+
+  if (m_trunking)
+    ::memcpy(m_idle, TERMINATOR_DATA, DMR_FRAME_LENGTH_BYTES);
+  else
+    ::memcpy(m_idle, IDLE_DATA, DMR_FRAME_LENGTH_BYTES);

  CDMRSlotType slotType;
-  slotType.encode(colorCode, DT_IDLE, m_idle);
+  if (m_trunking) {
+    slotType.encode(colorCode, DT_TERMINATOR_WITH_LC, m_idle);
+    slotType.encode(colorCode, DT_CSBK, m_aloha);
+  } else {
+    slotType.encode(colorCode, DT_IDLE, m_idle);
+  }
 }

 void CDMRTX::resetFifo1()
@@ -418,5 +464,12 @@ uint32_t CDMRTX::getFrameCount()
  return m_frameCount;
 }

-#endif
+void CDMRTX::setTrunking(bool trunking)
+{
+  m_trunking = trunking;

+  if (!trunking)
+    m_controlChannel = false;
+}
+
+#endif
@@ -1,6 +1,7 @@
 /*
 *   Copyright (C) 2015,2016,2017,2020 by Jonathan Naylor G4KLX
 *   Copyright (C) 2016 by Colin Durbridge G4EML
+ *   Copyright (C) 2026 by Adrian Musceac YO8RZZ
 *
 *   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
@@ -45,10 +46,12 @@ public:
  uint8_t writeData2(const uint8_t* data, uint16_t length);

  uint8_t writeShortLC(const uint8_t* data, uint16_t length);
+  uint8_t writeAloha(const uint8_t* data, uint16_t length);
  uint8_t writeAbort(const uint8_t* data, uint16_t length);

  void setStart(bool start);
  void setCal(bool start);
+  void setTrunking(bool trunking);

  void process();
  
@@ -62,11 +65,12 @@ public:
  void setColorCode(uint8_t colorCode);

 private:
-  CRingBuffer<uint8_t>                        m_fifo[2U];
+  CRingBuffer<uint8_t>             m_fifo[2U];
  arm_fir_interpolate_instance_q15 m_modFilter;
  q15_t                            m_modState[16U];    // blockSize + phaseLength - 1, 4 + 9 - 1 plus some spare
  DMRTXSTATE                       m_state;
  uint8_t                          m_idle[DMR_FRAME_LENGTH_BYTES];
+  uint8_t                          m_aloha[DMR_FRAME_LENGTH_BYTES];
  uint8_t                          m_cachPtr;
  uint8_t                          m_shortLC[12U];
  uint8_t                          m_newShortLC[12U];
@@ -77,6 +81,9 @@ private:
  uint32_t                         m_frameCount;
  uint32_t                         m_abortCount[2U];
  bool                             m_abort[2U];
+  bool                             m_controlChannel;
+  bool                             m_trunking;
+  uint8_t                          m_colorCode;

  void createData(uint8_t slotIndex);
  void createCACH(uint8_t txSlotIndex, uint8_t rxSlotIndex);
@@ -87,4 +94,3 @@ private:
 #endif

 #endif
-
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2020,2021,2023 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2020,2021,2023,2025 by Jonathan Naylor G4KLX
 *
 *   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
@@ -27,7 +27,8 @@ const uint16_t FM_TX_BLOCK_SIZE = 100U;
 const uint16_t FM_SERIAL_BLOCK_SIZE = 80U;//this is the number of sample pairs to send over serial. One sample pair is 3bytes.
                                          //three times this value shall never exceed 252
 const uint16_t FM_SERIAL_BLOCK_SIZE_BYTES = FM_SERIAL_BLOCK_SIZE * 3U;
-
+const uint16_t FM_LINK_EXT_GAP_MS = 60U;// How long a link-mode external-audio underrun is tolerated before it is
+                                        // treated as a real end of transmission (see linkStateMachine()).
 const uint8_t FS_LISTENING         = 0U;
 const uint8_t FS_KERCHUNK_RF       = 1U;
 const uint8_t FS_RELAYING_RF       = 2U;
@@ -62,10 +63,17 @@ m_ackMinTimer(),
 m_ackDelayTimer(),
 m_hangTimer(),
 m_reverseTimer(),
+m_extGapTimer(),
 m_needReverse(false),
 m_filterStage1(  724,   1448,   724, 32768, -37895, 21352),//3rd order Cheby Filter 300 to 2700Hz, 0.2dB passband ripple, sampling rate 24kHz
 m_filterStage2(32768,      0,-32768, 32768, -50339, 19052),
 m_filterStage3(32768, -65536, 32768, 32768, -64075, 31460),
+m_dsFilterStage1(m_filterStage1),//same coefficients, separate state
+m_dsFilterStage2(m_filterStage2),
+m_dsFilterStage3(m_filterStage3),
+m_usFilterStage1(m_filterStage1),//same coefficients, separate state
+m_usFilterStage2(m_filterStage2),
+m_usFilterStage3(m_filterStage3),
 m_blanking(),
 m_accessMode(1U),
 m_linkMode(false),
@@ -85,6 +93,7 @@ m_rssiAccum(0U),
 m_rssiCount(0U)
 {
  m_reverseTimer.setTimeout(0U, 150U);
+  m_extGapTimer.setTimeout(0U, FM_LINK_EXT_GAP_MS);

  insertDelay(100U);
 }
@@ -119,6 +128,7 @@ void CFM::repeaterSamples(bool cos, q15_t* samples, const uint16_t* rssi, uint8_

    q15_t currentExtSample;
    bool inputExt = m_inputExtRB.getSample(currentExtSample);//always consume the external input data so it does not overflow
+    currentExtSample = m_usFilterStage3.filter(m_usFilterStage2.filter(m_usFilterStage1.filter(currentExtSample)));
    inputExt = inputExt && m_extEnabled;

    switch (m_accessMode) {
@@ -200,8 +210,10 @@ void CFM::repeaterSamples(bool cos, q15_t* samples, const uint16_t* rssi, uint8_
    if (m_duplex) {
      if (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF || m_state == FS_RELAYING_EXT || m_state == FS_KERCHUNK_EXT) {
        currentSample = m_blanking.process(currentSample);
-        if (m_extEnabled && (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF))
-          m_downSampler.addSample(currentSample);
+        if (m_extEnabled && (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF)) {
+          q15_t dsSample = m_dsFilterStage3.filter(m_dsFilterStage2.filter(m_dsFilterStage1.filter(currentSample)));
+          m_downSampler.addSample(dsSample);
+        }

        currentSample *= currentBoost;
      } else {
@@ -211,9 +223,11 @@ void CFM::repeaterSamples(bool cos, q15_t* samples, const uint16_t* rssi, uint8_
        if (m_state == FS_RELAYING_EXT || m_state == FS_KERCHUNK_EXT) {
          currentSample *= currentBoost;
        } else {
-          if (m_extEnabled && (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF))
-            m_downSampler.addSample(currentSample);
-          continue; 
+          if (m_extEnabled && (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF)) {
+            q15_t dsSample = m_dsFilterStage3.filter(m_dsFilterStage2.filter(m_dsFilterStage1.filter(currentSample)));
+            m_downSampler.addSample(dsSample);
+          }
+          continue;
        }
    }

@@ -250,14 +264,17 @@ void CFM::linkSamples(bool cos, q15_t* samples, uint8_t length)

  uint8_t i = 0U;
  for (; i < length; i++) {
-    // ARMv7-M has hardware integer division 
    q15_t currentRFSample = q15_t((q31_t(samples[i]) << 8) / m_rxLevel);

    if (m_noiseSquelch)
      cos = m_squelch.process(currentRFSample);

-    q15_t currentExtSample;
+    // Zero-initialized: getSample() leaves this untouched on underrun, and
+    // with the ext-gap debounce below, m_extSignal can now stay true for a
+    // few samples past that point
+    q15_t currentExtSample = 0;
    bool inputExt = m_inputExtRB.getSample(currentExtSample);//always consume the external input data so it does not overflow
+    currentExtSample = m_usFilterStage3.filter(m_usFilterStage2.filter(m_usFilterStage1.filter(currentExtSample)));
    inputExt = inputExt && m_extEnabled;

    switch (m_accessMode) {
@@ -327,7 +344,8 @@ void CFM::linkSamples(bool cos, q15_t* samples, uint8_t length)

    if (m_rfSignal && m_extEnabled) {
      q15_t currentSample = m_blanking.process(currentRFSample);
-      m_downSampler.addSample(currentSample);
+      q15_t dsSample = m_dsFilterStage3.filter(m_dsFilterStage2.filter(m_dsFilterStage1.filter(currentSample)));
+      m_downSampler.addSample(dsSample);
    }

    if (!m_extSignal)
@@ -407,6 +425,12 @@ void CFM::reset()
  m_inputExtRB.reset();

  m_downSampler.reset();
+  m_dsFilterStage1.reset();
+  m_dsFilterStage2.reset();
+  m_dsFilterStage3.reset();
+  m_usFilterStage1.reset();
+  m_usFilterStage2.reset();
+  m_usFilterStage3.reset();
  m_squelch.reset();
  
  m_needReverse = false;
@@ -601,6 +625,7 @@ void CFM::clock(uint8_t length)
  m_ackDelayTimer.clock(length);
  m_hangTimer.clock(length);
  m_reverseTimer.clock(length);
+  m_extGapTimer.clock(length);
 }

 void CFM::listeningStateDuplex(bool validRFSignal, bool validExtSignal)
@@ -1231,6 +1256,12 @@ void CFM::linkStateMachine(bool validRFSignal, bool validExtSignal)
    m_extSignal = true;
  }

+  if (validExtSignal && m_extGapTimer.isRunning()) {
+    // Recovered before the gap timer committed to a real loss below --
+    // m_extSignal was never flipped, so there is nothing else to undo.
+    m_extGapTimer.stop();
+  }
+
  if (!validRFSignal && m_rfSignal) {
    io.setDecode(false);
    io.setADCDetection(false);
@@ -1248,14 +1279,28 @@ void CFM::linkStateMachine(bool validRFSignal, bool validExtSignal)
  }

  if (!validExtSignal && m_extSignal) {
-    if (!m_rfSignal) {
-      DEBUG1("State to LISTENING");
-      m_state = FS_LISTENING;
-      serial.writeFMStatus(m_state);
-    }
+    // A missed/late sample used to flip m_extSignal false right here, on
+    // the very first bad sample, with zero debounce -- that is what
+    // actually keys the transmitter off (IO::process() drops PTT the
+    // instant the downstream TX buffer runs dry, see IO.cpp). A gap well
+    // under FM_LINK_EXT_GAP_MS is less offensive than the PTT
+    // drop-and-rekey it triggers. Give it a short grace period
+    // mirroring the RELAYING_EXT/RELAYING_WAIT_EXT pattern the
+    // non-link duplex/simplex paths already use for exactly this
+    // situation (see relayingExtStateDuplex()/relayingExtWaitStateDuplex()).
+    if (!m_extGapTimer.isRunning()) {
+      m_extGapTimer.start();
+    } else if (m_extGapTimer.hasExpired()) {
+      if (!m_rfSignal) {
+        DEBUG1("State to LISTENING");
+        m_state = FS_LISTENING;
+        serial.writeFMStatus(m_state);
+      }

-    m_needReverse = true;
-    m_extSignal   = false;
+      m_needReverse = true;
+      m_extSignal   = false;
+      m_extGapTimer.stop();
+    }
  }
 }

@@ -1285,7 +1330,7 @@ uint8_t CFM::getSpace() const
  return m_inputExtRB.getSpace() / FM_SERIAL_BLOCK_SIZE_BYTES;
 }

-uint8_t CFM::writeData(const uint8_t* data, uint8_t length)
+uint8_t CFM::writeData(const uint8_t* data, uint16_t length)
 {
  //todo check if length is a multiple of 3
  m_inputExtRB.addData(data, length);
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2020,2021,2023 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2020,2021,2023,2025 by Jonathan Naylor G4KLX
 *
 *   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
@@ -53,7 +53,7 @@ public:

  uint8_t getSpace() const;

-  uint8_t writeData(const uint8_t* data, uint8_t length);
+  uint8_t writeData(const uint8_t* data, uint16_t length);

 private:
  CFMKeyer             m_callsign;
@@ -75,10 +75,17 @@ private:
  CFMTimer             m_ackDelayTimer;
  CFMTimer             m_hangTimer;
  CFMTimer             m_reverseTimer;
+  CFMTimer             m_extGapTimer;   // debounce for link-mode ext-audio underrun, see linkStateMachine()
  bool                 m_needReverse;
  CFMDirectFormI       m_filterStage1;
  CFMDirectFormI       m_filterStage2;
  CFMDirectFormI       m_filterStage3;
+  CFMDirectFormI       m_dsFilterStage1; // anti-alias filter for the downsampler, own state
+  CFMDirectFormI       m_dsFilterStage2;
+  CFMDirectFormI       m_dsFilterStage3;
+  CFMDirectFormI       m_usFilterStage1; // reconstruction filter for the upsampler, own state
+  CFMDirectFormI       m_usFilterStage2;
+  CFMDirectFormI       m_usFilterStage3;
  CFMBlanking          m_blanking;
  uint8_t              m_accessMode;
  bool                 m_linkMode;
@@ -34,6 +34,7 @@ m_sampleIndex(0U)

 void CFMDownSampler::addSample(q15_t sample)
 {
+  sample = __SSAT(sample, 12);//clamp before packing to 12 bits
  uint32_t usample = uint32_t(int32_t(sample) + 2048);
  //only take one of three samples
  switch(m_sampleIndex){
@@ -74,6 +75,8 @@ uint16_t CFMDownSampler::getData()
 void CFMDownSampler::reset()
 {
  m_sampleIndex = 0U;
+  m_samplePack  = 0U;
+  m_ringBuffer.reset();
 }

 #endif
@@ -36,7 +36,8 @@ m_count(0U),
 m_q0(0),
 m_q1(0),
 m_state(false),
-m_validCount(0U)
+m_validCount(0U),
+m_invalidCount(0U)
 {

 }
@@ -127,6 +128,8 @@ void CFMNoiseSquelch::reset()
  m_q1 = 0;
  m_state = false;
  m_count = 0U;
+  m_validCount = 0U;
+  m_invalidCount = 0U;
 }

 #endif
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017,2018,2020,2021 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2018,2020,2021,2025 by Jonathan Naylor G4KLX
 *
 *   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
@@ -48,9 +48,7 @@ enum MMDVM_STATE {
  STATE_P25       = 4,
  STATE_NXDN      = 5,
  STATE_POCSAG    = 6,
-  STATE_M17       = 7,
  STATE_FM        = 10,
-  STATE_AX25      = 11,

  // Dummy states start at 90
  STATE_NXDNCAL1K = 91,
@@ -69,8 +67,7 @@ enum MMDVM_STATE {
  STATE_FMCAL15K  = 104,
  STATE_FMCAL20K  = 105,
  STATE_FMCAL25K  = 106,
-  STATE_FMCAL30K  = 107,
-  STATE_M17CAL    = 108
+  STATE_FMCAL30K  = 107
 };

 #include "SerialPort.h"
@@ -85,8 +82,6 @@ enum MMDVM_STATE {
 #include "YSFTX.h"
 #include "P25RX.h"
 #include "P25TX.h"
-#include "M17RX.h"
-#include "M17TX.h"
 #include "NXDNRX.h"
 #include "NXDNTX.h"
 #include "POCSAGTX.h"
@@ -99,9 +94,6 @@ enum MMDVM_STATE {
 #include "CalPOCSAG.h"
 #include "CalRSSI.h"
 #include "CWIdTX.h"
-#include "AX25RX.h"
-#include "AX25TX.h"
-#include "CalM17.h"
 #include "Debug.h"
 #include "IO.h"
 #include "FM.h"
@@ -129,9 +121,7 @@ extern bool m_ysfEnable;
 extern bool m_p25Enable;
 extern bool m_nxdnEnable;
 extern bool m_pocsagEnable;
-extern bool m_m17Enable;
 extern bool m_fmEnable;
-extern bool m_ax25Enable;

 extern bool m_duplex;

@@ -184,23 +174,11 @@ extern CPOCSAGTX  pocsagTX;
 extern CCalPOCSAG calPOCSAG;
 #endif

-#if defined(MODE_M17)
-extern CM17RX m17RX;
-extern CM17TX m17TX;
-
-extern CCalM17 calM17;
-#endif
-
 #if defined(MODE_FM)
 extern CFM    fm;
 extern CCalFM calFM;
 #endif

-#if defined(MODE_AX25)
-extern CAX25RX ax25RX;
-extern CAX25TX ax25TX;
-#endif
-
 extern CCalRSSI calRSSI;

 extern CCWIdTX cwIdTX;
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017,2018,2020,2021,2023 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2018,2020,2021,2023,2025,2026 by Jonathan Naylor G4KLX
 *   Copyright (C) 2015 by Jim Mclaughlin KI6ZUM
 *   Copyright (C) 2016 by Colin Durbridge G4EML
 *
@@ -36,14 +36,6 @@ static q15_t RRC_0_2_FILTER[] = {401, 104, -340, -731, -847, -553, 112, 909, 147
 const uint16_t RRC_0_2_FILTER_LEN = 42U;
 #endif

-#if defined(MODE_M17)
-// Generated using rcosdesign(0.5, 8, 5, 'sqrt') in MATLAB
-static q15_t RRC_0_5_FILTER[] = {-147, -88, 72, 220, 223, 46, -197, -285, -79, 334, 623, 390, -498, -1691, -2363, -1556, 1284, 5872, 11033,
-				  15109, 16656, 15109, 11033, 5872, 1284, -1556, -2363, -1691, -498, 390, 623, 334, -79, -285, -197, 46, 223,
-				  220, 72, -88, -147, 0};
-const uint16_t RRC_0_5_FILTER_LEN = 42U;
-#endif
-
 #if defined(MODE_NXDN)
 #if defined(USE_NXDN_BOXCAR)
 // One symbol boxcar filter
@@ -114,10 +106,6 @@ m_nxdnState(),
 m_nxdnISincState(),
 #endif
 #endif
-#if defined(MODE_M17)
-m_rrc05Filter(),
-m_rrc05State(),
-#endif
 m_pttInvert(false),
 m_rxLevel(128 * 128),
 m_cwIdTXLevel(128 * 128),
@@ -126,10 +114,8 @@ m_dmrTXLevel(128 * 128),
 m_ysfTXLevel(128 * 128),
 m_p25TXLevel(128 * 128),
 m_nxdnTXLevel(128 * 128),
-m_m17TXLevel(128 * 128),
 m_pocsagTXLevel(128 * 128),
 m_fmTXLevel(128 * 128),
-m_ax25TXLevel(128 * 128),
 m_rxDCOffset(DC_OFFSET),
 m_txDCOffset(DC_OFFSET),
 m_useCOSAsLockout(false),
@@ -197,13 +183,6 @@ m_lockout(false)
 #endif
 #endif

-#if defined(MODE_M17)
-  ::memset(m_rrc05State, 0x00U, 70U * sizeof(q15_t));
-  m_rrc05Filter.numTaps = RRC_0_5_FILTER_LEN;
-  m_rrc05Filter.pState  = m_rrc05State;
-  m_rrc05Filter.pCoeffs = RRC_0_5_FILTER;
-#endif
-
  initInt();
  
  selfTest();
@@ -227,9 +206,6 @@ void CIO::selfTest()
 #if !defined(USE_ALTERNATE_NXDN_LEDS)
    setNXDNInt(ledValue);
 #endif
-#if !defined(USE_ALTERNATE_M17_LEDS)
-    setM17Int(ledValue);
-#endif
 #if !defined(USE_ALTERNATE_POCSAG_LEDS)
    setPOCSAGInt(ledValue);
 #endif
@@ -248,9 +224,6 @@ void CIO::selfTest()
 #if !defined(USE_ALTERNATE_NXDN_LEDS)
  setNXDNInt(false);
 #endif
-#if !defined(USE_ALTERNATE_M17_LEDS)
-  setM17Int(false);
-#endif
 #if !defined(USE_ALTERNATE_POCSAG_LEDS)
  setPOCSAGInt(false);
 #endif
@@ -273,11 +246,6 @@ void CIO::selfTest()
  setNXDNInt(true);
 #endif

-#if !defined(USE_ALTERNATE_M17_LEDS)
-  delayInt(250);
-  setM17Int(true);
-#endif
-
 #if !defined(USE_ALTERNATE_POCSAG_LEDS)
  delayInt(250);
  setPOCSAGInt(true);
@@ -296,11 +264,6 @@ void CIO::selfTest()
  setPOCSAGInt(false);
 #endif

-#if !defined(USE_ALTERNATE_M17_LEDS)
-  delayInt(250);
-  setM17Int(false);
-#endif
-
 #if !defined(USE_ALTERNATE_NXDN_LEDS)
  delayInt(250);
  setNXDNInt(false);
@@ -338,7 +301,7 @@ void CIO::process()
  if (m_started) {
    // Two seconds timeout
    if (m_watchdog >= 48000U) {
-      if (m_modemState == STATE_DSTAR || m_modemState == STATE_DMR || m_modemState == STATE_YSF || m_modemState == STATE_P25 || m_modemState == STATE_NXDN || m_modemState == STATE_M17 || m_modemState == STATE_POCSAG) {
+      if (m_modemState == STATE_DSTAR || m_modemState == STATE_DMR || m_modemState == STATE_YSF || m_modemState == STATE_P25 || m_modemState == STATE_NXDN || m_modemState == STATE_POCSAG) {
 #if defined(MODE_DMR)
        if (m_modemState == STATE_DMR && m_tx)
          dmrTX.setStart(false);
@@ -490,18 +453,6 @@ void CIO::process()
      }
 #endif

-#if defined(MODE_M17)
-      if (m_m17Enable) {
-        q15_t RRCVals[RX_BLOCK_SIZE];
-#if defined(USE_DCBLOCKER)
-        ::arm_fir_fast_q15(&m_rrc05Filter, dcSamples, RRCVals, RX_BLOCK_SIZE);
-#else
-        ::arm_fir_fast_q15(&m_rrc05Filter, samples, RRCVals, RX_BLOCK_SIZE);
-#endif
-        m17RX.samples(RRCVals, rssi, RX_BLOCK_SIZE);
-      }
-#endif
-
 #if defined(MODE_FM)
      if (m_fmEnable) {
        bool cos = getCOSInt();
@@ -512,16 +463,6 @@ void CIO::process()
 #endif
      }
 #endif
-
-#if defined(MODE_FM) && defined(MODE_AX25)
-      if (m_ax25Enable) {
-#if defined(USE_DCBLOCKER)
-        ax25RX.samples(dcSamples, rssi, RX_BLOCK_SIZE);
-#else
-        ax25RX.samples(samples, rssi, RX_BLOCK_SIZE);
-#endif
-      }
-#endif
    }

 #if defined(MODE_DSTAR)
@@ -609,37 +550,13 @@ void CIO::process()
    }
 #endif

-#if defined(MODE_M17)
-    else if (m_modemState == STATE_M17) {
-      if (m_m17Enable) {
-        q15_t M17Vals[RX_BLOCK_SIZE];
-#if defined(USE_DCBLOCKER)
-        ::arm_fir_fast_q15(&m_rrc05Filter, dcSamples, M17Vals, RX_BLOCK_SIZE);
-#else
-        ::arm_fir_fast_q15(&m_rrc05Filter, samples, M17Vals, RX_BLOCK_SIZE);
-#endif
-        m17RX.samples(M17Vals, rssi, RX_BLOCK_SIZE);
-      }
-    }
-#endif
-
 #if defined(MODE_FM)
    else if (m_modemState == STATE_FM) {
      bool cos = getCOSInt();
 #if defined(USE_DCBLOCKER)
      fm.samples(cos, dcSamples, rssi, RX_BLOCK_SIZE);
-
-#if defined(MODE_AX25)
-      if (m_ax25Enable)
-        ax25RX.samples(dcSamples, rssi, RX_BLOCK_SIZE);
-#endif
 #else
      fm.samples(cos, samples, rssi, RX_BLOCK_SIZE);
-
-#if defined(MODE_AX25)
-      if (m_ax25Enable)
-        ax25RX.samples(samples, rssi, RX_BLOCK_SIZE);
-#endif
 #endif
    }
 #endif
@@ -691,18 +608,12 @@ void CIO::write(MMDVM_STATE mode, q15_t* samples, uint16_t length, const uint8_t
    case STATE_NXDN:
      txLevel = m_nxdnTXLevel;
      break;
-    case STATE_M17:
-      txLevel = m_m17TXLevel;
-      break;
    case STATE_POCSAG:
      txLevel = m_pocsagTXLevel;
      break;
    case STATE_FM:
      txLevel = m_fmTXLevel;
      break;
-    case STATE_AX25:
-      txLevel = m_ax25TXLevel;
-      break;
    default:
      txLevel = m_cwIdTXLevel;
      break;
@@ -754,7 +665,6 @@ void CIO::setMode(MMDVM_STATE state)
    case STATE_YSF:    setYSFInt(false);    break;
    case STATE_P25:    setP25Int(false);    break;
    case STATE_NXDN:   setNXDNInt(false);   break;
-    case STATE_M17:    setM17Int(false);    break;
    case STATE_POCSAG: setPOCSAGInt(false); break;
    case STATE_FM:     setFMInt(false);     break;
    default: break;
@@ -766,7 +676,6 @@ void CIO::setMode(MMDVM_STATE state)
    case STATE_YSF:    setYSFInt(true);    break;
    case STATE_P25:    setP25Int(true);    break;
    case STATE_NXDN:   setNXDNInt(true);   break;
-    case STATE_M17:    setM17Int(true);    break;
    case STATE_POCSAG: setPOCSAGInt(true); break;
    case STATE_FM:     setFMInt(true);     break;
    default: break;
@@ -776,7 +685,7 @@ void CIO::setMode(MMDVM_STATE state)
  m_modemState = state;
 }

-void CIO::setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rxLevel, uint8_t cwIdTXLevel, uint8_t dstarTXLevel, uint8_t dmrTXLevel, uint8_t ysfTXLevel, uint8_t p25TXLevel, uint8_t nxdnTXLevel, uint8_t m17TXLevel, uint8_t pocsagTXLevel, uint8_t fmTXLevel, uint8_t ax25TXLevel, int16_t txDCOffset, int16_t rxDCOffset, bool useCOSAsLockout)
+void CIO::setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rxLevel, uint8_t cwIdTXLevel, uint8_t dstarTXLevel, uint8_t dmrTXLevel, uint8_t ysfTXLevel, uint8_t p25TXLevel, uint8_t nxdnTXLevel, uint8_t pocsagTXLevel, uint8_t fmTXLevel, int16_t txDCOffset, int16_t rxDCOffset, bool useCOSAsLockout)
 {
  m_pttInvert = pttInvert;

@@ -787,10 +696,8 @@ void CIO::setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rx
  m_ysfTXLevel    = q15_t(ysfTXLevel * 128);
  m_p25TXLevel    = q15_t(p25TXLevel * 128);
  m_nxdnTXLevel   = q15_t(nxdnTXLevel * 128);
-  m_m17TXLevel    = q15_t(m17TXLevel * 128);
  m_pocsagTXLevel = q15_t(pocsagTXLevel * 128);
  m_fmTXLevel     = q15_t(fmTXLevel * 128);
-  m_ax25TXLevel   = q15_t(ax25TXLevel * 128);

  m_rxDCOffset   = DC_OFFSET + rxDCOffset;
  m_txDCOffset   = DC_OFFSET + txDCOffset;
@@ -806,7 +713,6 @@ void CIO::setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rx
    m_ysfTXLevel    = -m_ysfTXLevel;
    m_p25TXLevel    = -m_p25TXLevel;
    m_nxdnTXLevel   = -m_nxdnTXLevel;
-    m_m17TXLevel    = -m_m17TXLevel;
    m_pocsagTXLevel = -m_pocsagTXLevel;
  }
 }
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017,2018,2020,2021 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2018,2020,2021,2025 by Jonathan Naylor G4KLX
 *
 *   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
@@ -46,7 +46,7 @@ public:
  
  void interrupt();

-  void setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rxLevel, uint8_t cwIdTXLevel, uint8_t dstarTXLevel, uint8_t dmrTXLevel, uint8_t ysfTXLevel, uint8_t p25TXLevel, uint8_t nxdnTXLevel, uint8_t m17TXLevel, uint8_t pocsagTXLevel, uint8_t fmTXLevel, uint8_t ax25TXLevel, int16_t txDCOffset, int16_t rxDCOffset, bool useCOSAsLockout);
+  void setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rxLevel, uint8_t cwIdTXLevel, uint8_t dstarTXLevel, uint8_t dmrTXLevel, uint8_t ysfTXLevel, uint8_t p25TXLevel, uint8_t nxdnTXLevel, uint8_t pocsagTXLevel, uint8_t fmTXLevel, int16_t txDCOffset, int16_t rxDCOffset, bool useCOSAsLockout);

  void getOverflow(bool& adcOverflow, bool& dacOverflow);

@@ -108,11 +108,6 @@ private:
 #endif
 #endif

-#if defined(MODE_M17)
-  arm_fir_instance_q15 m_rrc05Filter;
-  q15_t                m_rrc05State[70U];         // NoTaps + BlockSize - 1, 42 + 20 - 1 plus some spare
-#endif
-
  bool                 m_pttInvert;
  q15_t                m_rxLevel;
  q15_t                m_cwIdTXLevel;
@@ -121,10 +116,8 @@ private:
  q15_t                m_ysfTXLevel;
  q15_t                m_p25TXLevel;
  q15_t                m_nxdnTXLevel;
-  q15_t                m_m17TXLevel;
  q15_t                m_pocsagTXLevel;
  q15_t                m_fmTXLevel;
-  q15_t                m_ax25TXLevel;

  uint16_t             m_rxDCOffset;
  uint16_t             m_txDCOffset;
@@ -159,10 +152,10 @@ private:
  void setP25Int(bool on);
  void setNXDNInt(bool on);
  void setPOCSAGInt(bool on);
-  void setM17Int(bool on);
  void setFMInt(bool on);
  
  void delayInt(unsigned int dly);
 };

 #endif
+
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017,2018,2020 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2018,2020,2025 by Jonathan Naylor G4KLX
 *   Copyright (C) 2015 by Jim Mclaughlin KI6ZUM
 *   Copyright (C) 2016 by Colin Durbridge G4EML
 *
@@ -107,13 +107,10 @@ void CIO::initInt()
 #if !defined(USE_ALTERNATE_NXDN_LEDS)
  pinMode(PIN_NXDN,   OUTPUT);
 #endif
-#if !defined(USE_ALTERNATE_M17_LEDS)
-  pinMode(PIN_M17,    OUTPUT);
-#endif
 #if !defined(USE_ALTERNATE_POCSAG_LEDS)
  pinMode(PIN_POCSAG, OUTPUT);
 #endif
-#if !defined(USE_ALTERNATE_POCSAG_LEDS)
+#if !defined(USE_ALTERNATE_FM_LEDS)
  pinMode(PIN_FM,     OUTPUT);
 #endif
 #endif
@@ -256,16 +253,6 @@ void CIO::setNXDNInt(bool on)
 #endif
 }

-void CIO::setM17Int(bool on)
-{
-#if defined(USE_ALTERNATE_M17_LEDS)
-  digitalWrite(PIN_DSTAR, on ? HIGH : LOW);
-  digitalWrite(PIN_P25,   on ? HIGH : LOW);
-#else
-  digitalWrite(PIN_M17, on ? HIGH : LOW);
-#endif
-}
-
 void CIO::setPOCSAGInt(bool on)
 {
 #if defined(USE_ALTERNATE_POCSAG_LEDS)
@@ -1,7 +1,7 @@
 /*
 *   Copyright (C) 2016 by Jim McLaughlin KI6ZUM
 *   Copyright (C) 2016,2017,2018 by Andy Uribe CA6JAU
- *   Copyright (C) 2017,2018,2020,2023 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2017,2018,2020,2023,2025 by Jonathan Naylor G4KLX
 *   Copyright (C) 2019,2020 by BG5HHP
 *
 *   This program is free software; you can redistribute it and/or modify
@@ -106,14 +106,6 @@ void CIO::initInt()
   GPIO_Init(PORT_NXDN, &GPIO_InitStruct);
 #endif

-#if !defined(USE_ALTERNATE_M17_LEDS)
-   // M17 pin
-   RCC_AHB1PeriphClockCmd(RCC_Per_M17, ENABLE);
-   GPIO_InitStruct.GPIO_Pin   = PIN_M17;
-   GPIO_InitStruct.GPIO_Mode  = GPIO_Mode_OUT;
-   GPIO_Init(PORT_M17, &GPIO_InitStruct);
-#endif
-
 #if !defined(USE_ALTERNATE_POCSAG_LEDS)
   // POCSAG pin
   RCC_AHB1PeriphClockCmd(RCC_Per_POCSAG, ENABLE);
@@ -165,14 +157,6 @@ void CIO::initInt()
   GPIO_Init(PORT_MNXDN, &GPIO_InitStruct);
 #endif

-#if !defined(USE_ALTERNATE_M17_LEDS)
-   // M17 mode pin
-   RCC_AHB1PeriphClockCmd(RCC_Per_MM17, ENABLE);
-   GPIO_InitStruct.GPIO_Pin   = PIN_MM17;
-   GPIO_InitStruct.GPIO_Mode  = GPIO_Mode_OUT;
-   GPIO_Init(PORT_MM17, &GPIO_InitStruct);
-#endif
-
 #if !defined(USE_ALTERNATE_POCSAG_LEDS)
   // POCSAG mode pin
   RCC_AHB1PeriphClockCmd(RCC_Per_MPOCSAG, ENABLE);
@@ -462,27 +446,6 @@ void CIO::setNXDNInt(bool on)
 #endif
 }

-void CIO::setM17Int(bool on)
-{
-#if defined(MODE_LEDS)
-#if defined(USE_ALTERNATE_M17_LEDS)
-   GPIO_WriteBit(PORT_DSTAR, PIN_DSTAR, on ? Bit_SET : Bit_RESET);
-   GPIO_WriteBit(PORT_P25,   PIN_P25, on ? Bit_SET : Bit_RESET);
-#else
-   GPIO_WriteBit(PORT_M17, PIN_M17, on ? Bit_SET : Bit_RESET);
-#endif
-#endif
-
-#if defined(MODE_PINS) && defined(STM32F4_NUCLEO_MORPHO_HEADER) && (defined(STM32F4_NUCLEO) || defined(STM32F722_RPT_HAT))
-#if defined(USE_ALTERNATE_M17_LEDS)
-   GPIO_WriteBit(PORT_MDSTAR, PIN_MDSTAR, on ? Bit_SET : Bit_RESET);
-   GPIO_WriteBit(PORT_MP25,   PIN_MP25,   on ? Bit_SET : Bit_RESET);
-#else
-   GPIO_WriteBit(PORT_MM17, PIN_MM17, on ? Bit_SET : Bit_RESET);
-#endif
-#endif
-}
-
 void CIO::setPOCSAGInt(bool on)
 {
 #if defined(MODE_LEDS)
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2016,2017,2018,2020 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2016,2017,2018,2020,2025 by Jonathan Naylor G4KLX
 *
 *   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
@@ -75,9 +75,6 @@ void CIO::initInt()
 #if !defined(USE_ALTERNATE_NXDN_LEDS)
  pinMode(PIN_NXDN,   OUTPUT);
 #endif
-#if !defined(USE_ALTERNATE_M17_LEDS)
-  pinMode(PIN_M17,    OUTPUT);
-#endif
 #if !defined(USE_ALTERNATE_POCSAG_LEDS)
  pinMode(PIN_POCSAG, OUTPUT);
 #endif
@@ -240,16 +237,6 @@ void CIO::setNXDNInt(bool on)
 #endif
 }

-void CIO::setM17Int(bool on)
-{
-#if defined(USE_ALTERNATE_M17_LEDS)
-  digitalWrite(PIN_DSTAR, on ? HIGH : LOW);
-  digitalWrite(PIN_P25,   on ? HIGH : LOW);
-#else
-  digitalWrite(PIN_M17, on ? HIGH : LOW);
-#endif
-}
-
 void CIO::setPOCSAGInt(bool on)
 {
 #if defined(USE_ALTERNATE_POCSAG_LEDS)
@@ -1,67 +0,0 @@
-/*
- *   Copyright (C) 2016,2017,2018,2020,2021 by Jonathan Naylor G4KLX
- *
- *   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.
- */
-
-#if !defined(M17DEFINES_H)
-#define  M17DEFINES_H
-
-const unsigned int M17_RADIO_SYMBOL_LENGTH = 5U;      // At 24 kHz sample rate
-
-const unsigned int M17_FRAME_LENGTH_BITS    = 384U;
-const unsigned int M17_FRAME_LENGTH_BYTES   = M17_FRAME_LENGTH_BITS / 8U;
-const unsigned int M17_FRAME_LENGTH_SYMBOLS = M17_FRAME_LENGTH_BITS / 2U;
-const unsigned int M17_FRAME_LENGTH_SAMPLES = M17_FRAME_LENGTH_SYMBOLS * M17_RADIO_SYMBOL_LENGTH;
-
-const unsigned int M17_SYNC_LENGTH_BITS    = 16U;
-const unsigned int M17_SYNC_LENGTH_BYTES   = M17_SYNC_LENGTH_BITS / 8U;
-const unsigned int M17_SYNC_LENGTH_SYMBOLS = M17_SYNC_LENGTH_BITS / 2U;
-const unsigned int M17_SYNC_LENGTH_SAMPLES = M17_SYNC_LENGTH_SYMBOLS * M17_RADIO_SYMBOL_LENGTH;
-
-const uint8_t M17_LINK_SETUP_SYNC_BYTES[] = {0x55U, 0xF7U};
-const uint8_t M17_STREAM_SYNC_BYTES[]     = {0xFFU, 0x5DU};
-const uint8_t M17_EOF_SYNC_BYTES[]        = {0x55U, 0x5DU};
-
-const uint16_t M17_LINK_SETUP_SYNC_BITS = 0x55F7U;
-const uint16_t M17_STREAM_SYNC_BITS     = 0xFF5DU;
-const uint16_t M17_EOF_SYNC_BITS        = 0x555DU;
-
-// 5     5     F     7
-// 01 01 01 01 11 11 01 11
-// +3 +3 +3 +3 -3 -3 +3 -3
-
-const int8_t M17_LINK_SETUP_SYNC_SYMBOLS_VALUES[] = {+3, +3, +3, +3, -3, -3, +3, -3};
-
-const uint8_t M17_LINK_SETUP_SYNC_SYMBOLS = 0xF2U;
-
-// F     F     5     D
-// 11 11 11 11 01 01 11 01
-// -3 -3 -3 -3 +3 +3 -3 +3
-
-const int8_t M17_STREAM_SYNC_SYMBOLS_VALUES[] = {-3, -3, -3, -3, +3, +3, -3, +3};
-
-const uint8_t M17_STREAM_SYNC_SYMBOLS = 0x0DU;
-
-// 5     5     5     D
-// 01 01 01 01 01 01 11 01
-// +3 +3 +3 +3 +3 +3 -3 +3
-
-const int8_t M17_EOF_SYNC_SYMBOLS_VALUES[] = {+3, +3, +3, +3, +3, +3, -3, +3};
-
-const uint8_t M17_EOF_SYNC_SYMBOLS = 0xFDU;
-
-#endif
-
@@ -1,485 +0,0 @@
-/*
- *   Copyright (C) 2009-2017,2020,2021 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_M17)
-
-#include "Globals.h"
-#include "M17RX.h"
-#include "Utils.h"
-
-const q15_t SCALING_FACTOR = 18750;      // Q15(0.55)
-
-const uint8_t MAX_SYNC_BIT_START_ERRS = 0U;
-const uint8_t MAX_SYNC_BIT_RUN_ERRS   = 2U;
-
-const uint8_t MAX_SYNC_SYMBOL_START_ERRS = 0U;
-const uint8_t MAX_SYNC_SYMBOL_RUN_ERRS   = 1U;
-
-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 = 3U + 1U;
-
-CM17RX::CM17RX() :
-m_state(M17RXS_NONE),
-m_bitBuffer(),
-m_buffer(),
-m_bitPtr(0U),
-m_dataPtr(0U),
-m_startPtr(NOENDPTR),
-m_endPtr(NOENDPTR),
-m_syncPtr(NOENDPTR),
-m_minSyncPtr(NOENDPTR),
-m_maxSyncPtr(NOENDPTR),
-m_maxCorr(0),
-m_lostCount(0U),
-m_countdown(0U),
-m_nextState(M17RXS_NONE),
-m_centre(),
-m_centreVal(0),
-m_threshold(),
-m_thresholdVal(0),
-m_averagePtr(NOAVEPTR),
-m_rssiAccum(0U),
-m_rssiCount(0U)
-{
-}
-
-void CM17RX::reset()
-{
-  m_state        = M17RXS_NONE;
-  m_dataPtr      = 0U;
-  m_bitPtr       = 0U;
-  m_maxCorr      = 0;
-  m_averagePtr   = NOAVEPTR;
-  m_startPtr     = NOENDPTR;
-  m_endPtr       = NOENDPTR;
-  m_syncPtr      = NOENDPTR;
-  m_minSyncPtr   = NOENDPTR;
-  m_maxSyncPtr   = NOENDPTR;
-  m_centreVal    = 0;
-  m_thresholdVal = 0;
-  m_lostCount    = 0U;
-  m_countdown    = 0U;
-  m_nextState    = M17RXS_NONE;
-  m_rssiAccum    = 0U;
-  m_rssiCount    = 0U;
-}
-
-void CM17RX::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 M17RXS_LINK_SETUP:
-    case M17RXS_STREAM:
-      processData(sample);
-      break;
-    default:
-      processNone(sample);
-      break;
-    }
-
-    m_dataPtr++;
-    if (m_dataPtr >= M17_FRAME_LENGTH_SAMPLES)
-      m_dataPtr = 0U;
-
-    m_bitPtr++;
-    if (m_bitPtr >= M17_RADIO_SYMBOL_LENGTH)
-      m_bitPtr = 0U;
-  }
-}
-
-void CM17RX::processNone(q15_t sample)
-{
-  bool ret1 = correlateSync(M17_LINK_SETUP_SYNC_SYMBOLS, M17_LINK_SETUP_SYNC_SYMBOLS_VALUES, M17_LINK_SETUP_SYNC_BYTES, MAX_SYNC_SYMBOL_START_ERRS, MAX_SYNC_BIT_START_ERRS);
-  bool ret2 = correlateSync(M17_STREAM_SYNC_SYMBOLS,     M17_STREAM_SYNC_SYMBOLS_VALUES,     M17_STREAM_SYNC_BYTES,     MAX_SYNC_SYMBOL_START_ERRS, MAX_SYNC_BIT_START_ERRS);
-
-  if (ret1 || ret2) {
-    // 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 = 5U;
-      
-      if (ret1) m_nextState = M17RXS_LINK_SETUP;
-      if (ret2) m_nextState = M17RXS_STREAM;
-    }
-  }
-
-  if (m_countdown > 0U)
-    m_countdown--;
-
-  if (m_countdown == 1U) {
-    m_minSyncPtr = m_syncPtr + M17_FRAME_LENGTH_SAMPLES - 1U;
-    if (m_minSyncPtr >= M17_FRAME_LENGTH_SAMPLES)
-      m_minSyncPtr -= M17_FRAME_LENGTH_SAMPLES;
-
-    m_maxSyncPtr = m_syncPtr + 1U;
-    if (m_maxSyncPtr >= M17_FRAME_LENGTH_SAMPLES)
-      m_maxSyncPtr -= M17_FRAME_LENGTH_SAMPLES;
-
-    m_state     = m_nextState;
-    m_countdown = 0U;
-    m_nextState = M17RXS_NONE;
-  }
-}
-
-void CM17RX::processData(q15_t sample)
-{
-  bool eof = false;
-
-  if (m_minSyncPtr < m_maxSyncPtr) {
-    if (m_dataPtr >= m_minSyncPtr && m_dataPtr <= m_maxSyncPtr) {
-      bool ret = correlateSync(M17_STREAM_SYNC_SYMBOLS, M17_STREAM_SYNC_SYMBOLS_VALUES, M17_STREAM_SYNC_BYTES,  MAX_SYNC_SYMBOL_RUN_ERRS, MAX_SYNC_BIT_RUN_ERRS);
-
-      eof = correlateSync(M17_EOF_SYNC_SYMBOLS, M17_EOF_SYNC_SYMBOLS_VALUES, M17_EOF_SYNC_BYTES, MAX_SYNC_SYMBOL_RUN_ERRS, MAX_SYNC_BIT_RUN_ERRS);
-
-      if (ret) m_state = M17RXS_STREAM;
-    }
-  } else {
-    if (m_dataPtr >= m_minSyncPtr || m_dataPtr <= m_maxSyncPtr) {
-      bool ret = correlateSync(M17_STREAM_SYNC_SYMBOLS, M17_STREAM_SYNC_SYMBOLS_VALUES, M17_STREAM_SYNC_BYTES,  MAX_SYNC_SYMBOL_RUN_ERRS, MAX_SYNC_BIT_RUN_ERRS);
-
-      eof = correlateSync(M17_EOF_SYNC_SYMBOLS, M17_EOF_SYNC_SYMBOLS_VALUES, M17_EOF_SYNC_BYTES, MAX_SYNC_SYMBOL_RUN_ERRS, MAX_SYNC_BIT_RUN_ERRS);
-
-      if (ret) m_state = M17RXS_STREAM;
-    }
-  }
-
-  if (eof) {
-    DEBUG4("M17RX: eof sync found pos/centre/threshold", m_syncPtr, m_centreVal, m_thresholdVal);
-
-    io.setDecode(false);
-    io.setADCDetection(false);
-
-    serial.writeM17EOT();
-
-    m_state      = M17RXS_NONE;
-    m_endPtr     = NOENDPTR;
-    m_averagePtr = NOAVEPTR;
-    m_countdown  = 0U;
-    m_nextState  = M17RXS_NONE;
-    m_maxCorr    = 0;
-  }
-
-  if (m_dataPtr == m_endPtr) {
-    // Only update the centre and threshold if they are from a good sync
-    if (m_lostCount == MAX_SYNC_FRAMES) {
-      m_minSyncPtr = m_syncPtr + M17_FRAME_LENGTH_SAMPLES - 1U;
-      if (m_minSyncPtr >= M17_FRAME_LENGTH_SAMPLES)
-        m_minSyncPtr -= M17_FRAME_LENGTH_SAMPLES;
-
-      m_maxSyncPtr = m_syncPtr + 1U;
-      if (m_maxSyncPtr >= M17_FRAME_LENGTH_SAMPLES)
-        m_maxSyncPtr -= M17_FRAME_LENGTH_SAMPLES;
-    }
-
-    calculateLevels(m_startPtr, M17_FRAME_LENGTH_SYMBOLS);
-
-    switch (m_state) {
-      case M17RXS_LINK_SETUP:
-        DEBUG4("M17RX: link setup sync found pos/centre/threshold", m_syncPtr, m_centreVal, m_thresholdVal);
-        break;
-      case M17RXS_STREAM:
-        DEBUG4("M17RX: stream sync found pos/centre/threshold", m_syncPtr, m_centreVal, m_thresholdVal);
-        break;
-      default:
-        break;  
-    }
-
-    uint8_t frame[M17_FRAME_LENGTH_BYTES + 3U];
-    samplesToBits(m_startPtr, M17_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
-
-    // We've not seen a stream sync for too long, signal RXLOST and change to RX_NONE
-    m_lostCount--;
-    if (m_lostCount == 0U) {
-      DEBUG1("M17RX: sync timed out, lost lock");
-
-      io.setDecode(false);
-      io.setADCDetection(false);
-
-      serial.writeM17Lost();
-
-      m_state      = M17RXS_NONE;
-      m_endPtr     = NOENDPTR;
-      m_averagePtr = NOAVEPTR;
-      m_countdown  = 0U;
-      m_nextState  = M17RXS_NONE;
-      m_maxCorr    = 0;
-    } else {
-      frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
-
-      switch (m_state) {
-        case M17RXS_LINK_SETUP:
-          writeRSSILinkSetup(frame);
-          break;
-        case M17RXS_STREAM:
-          writeRSSIStream(frame);
-          break;
-        default:
-          break;  
-      }
-
-      m_maxCorr   = 0;
-      m_nextState = M17RXS_NONE;
-    }
-  }
-}
-
-bool CM17RX::correlateSync(uint8_t syncSymbols, const int8_t* syncSymbolValues, const uint8_t* syncBytes, uint8_t maxSymbolErrs, uint8_t maxBitErrs)
-{
-  if (countBits8(m_bitBuffer[m_bitPtr] ^ syncSymbols) <= maxSymbolErrs) {
-    uint16_t ptr = m_dataPtr + M17_FRAME_LENGTH_SAMPLES - M17_SYNC_LENGTH_SAMPLES + M17_RADIO_SYMBOL_LENGTH;
-    if (ptr >= M17_FRAME_LENGTH_SAMPLES)
-      ptr -= M17_FRAME_LENGTH_SAMPLES;
-
-    q31_t corr = 0;
-    q15_t min =  16000;
-    q15_t max = -16000;
-
-    for (uint8_t i = 0U; i < M17_SYNC_LENGTH_SYMBOLS; i++) {
-      q15_t val = m_buffer[ptr];
-
-      if (val > max)
-        max = val;
-      if (val < min)
-        min = val;
-
-      switch (syncSymbolValues[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 += M17_RADIO_SYMBOL_LENGTH;
-      if (ptr >= M17_FRAME_LENGTH_SAMPLES)
-        ptr -= M17_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 + M17_FRAME_LENGTH_SAMPLES - M17_SYNC_LENGTH_SAMPLES + M17_RADIO_SYMBOL_LENGTH;
-      if (startPtr >= M17_FRAME_LENGTH_SAMPLES)
-        startPtr -= M17_FRAME_LENGTH_SAMPLES;
-
-      uint8_t sync[M17_SYNC_LENGTH_BYTES];
-      samplesToBits(startPtr, M17_SYNC_LENGTH_SYMBOLS, sync, 0U, m_centreVal, m_thresholdVal);
-
-      uint8_t errs = 0U;
-      for (uint8_t i = 0U; i < M17_SYNC_LENGTH_BYTES; i++)
-        errs += countBits8(sync[i] ^ syncBytes[i]);
-
-      if (errs <= maxBitErrs) {
-        m_maxCorr   = corr;
-        m_lostCount = MAX_SYNC_FRAMES;
-        m_syncPtr   = m_dataPtr;
-
-        m_startPtr = startPtr;
-
-        m_endPtr = m_dataPtr + M17_FRAME_LENGTH_SAMPLES - M17_SYNC_LENGTH_SAMPLES - 1U;
-        if (m_endPtr >= M17_FRAME_LENGTH_SAMPLES)
-          m_endPtr -= M17_FRAME_LENGTH_SAMPLES;
-
-        return true;
-      }
-    }
-  }
-
-  return false;
-}
-
-void CM17RX::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 += M17_RADIO_SYMBOL_LENGTH;
-    if (start >= M17_FRAME_LENGTH_SAMPLES)
-      start -= M17_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("M17RX: 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 CM17RX::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 += M17_RADIO_SYMBOL_LENGTH;
-    if (start >= M17_FRAME_LENGTH_SAMPLES)
-      start -= M17_FRAME_LENGTH_SAMPLES;
-  }
-}
-
-void CM17RX::writeRSSILinkSetup(uint8_t* data)
-{
-#if defined(SEND_RSSI_DATA)
-  if (m_rssiCount > 0U) {
-    uint16_t rssi = m_rssiAccum / m_rssiCount;
-
-    data[49U] = (rssi >> 8) & 0xFFU;
-    data[50U] = (rssi >> 0) & 0xFFU;
-
-    serial.writeM17LinkSetup(data, M17_FRAME_LENGTH_BYTES + 3U);
-  } else {
-    serial.writeM17LinkSetup(data, M17_FRAME_LENGTH_BYTES + 1U);
-  }
-#else
-  serial.writeM17LinkSetup(data, M17_FRAME_LENGTH_BYTES + 1U);
-#endif
-
-  m_rssiAccum = 0U;
-  m_rssiCount = 0U;
-}
-
-void CM17RX::writeRSSIStream(uint8_t* data)
-{
-#if defined(SEND_RSSI_DATA)
-  if (m_rssiCount > 0U) {
-    uint16_t rssi = m_rssiAccum / m_rssiCount;
-
-    data[49U] = (rssi >> 8) & 0xFFU;
-    data[50U] = (rssi >> 0) & 0xFFU;
-
-    serial.writeM17Stream(data, M17_FRAME_LENGTH_BYTES + 3U);
-  } else {
-    serial.writeM17Stream(data, M17_FRAME_LENGTH_BYTES + 1U);
-  }
-#else
-  serial.writeM17Stream(data, M17_FRAME_LENGTH_BYTES + 1U);
-#endif
-
-  m_rssiAccum = 0U;
-  m_rssiCount = 0U;
-}
-
-#endif
-
@@ -1,77 +0,0 @@
-/*
- *   Copyright (C) 2015,2016,2017,2020,2021 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_M17)
-
-#if !defined(M17RX_H)
-#define  M17RX_H
-
-#include "M17Defines.h"
-
-enum M17RX_STATE {
-  M17RXS_NONE,
-  M17RXS_LINK_SETUP,
-  M17RXS_STREAM
-};
-
-class CM17RX {
-public:
-  CM17RX();
-
-  void samples(const q15_t* samples, uint16_t* rssi, uint8_t length);
-
-  void reset();
-
-private:
-  M17RX_STATE m_state;
-  uint8_t     m_bitBuffer[M17_RADIO_SYMBOL_LENGTH];
-  q15_t       m_buffer[M17_FRAME_LENGTH_SAMPLES];
-  uint16_t    m_bitPtr;
-  uint16_t    m_dataPtr;
-  uint16_t    m_startPtr;
-  uint16_t    m_endPtr;
-  uint16_t    m_syncPtr;
-  uint16_t    m_minSyncPtr;
-  uint16_t    m_maxSyncPtr;
-  q31_t       m_maxCorr;
-  uint16_t    m_lostCount;
-  uint8_t     m_countdown;
-  M17RX_STATE m_nextState;
-  q15_t       m_centre[16U];
-  q15_t       m_centreVal;
-  q15_t       m_threshold[16U];
-  q15_t       m_thresholdVal;
-  uint8_t     m_averagePtr;
-  uint32_t    m_rssiAccum;
-  uint16_t    m_rssiCount;
-
-  void processNone(q15_t sample);
-  void processData(q15_t sample);
-  bool correlateSync(uint8_t syncSymbols, const int8_t* syncSymbolValues, const uint8_t* syncBytes, uint8_t maxSymbolErrs, uint8_t maxBitErrs);
-  void calculateLevels(uint16_t start, uint16_t count);
-  void samplesToBits(uint16_t start, uint16_t count, uint8_t* buffer, uint16_t offset, q15_t centre, q15_t threshold);
-  void writeRSSILinkSetup(uint8_t* data);
-  void writeRSSIStream(uint8_t* data);
-};
-
-#endif
-
-#endif
-
@@ -1,190 +0,0 @@
-/*
- *   Copyright (C) 2009-2018,2020,2021 by Jonathan Naylor G4KLX
- *   Copyright (C) 2017 by Andy Uribe CA6JAU
- *
- *   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"
-
-#if defined(MODE_M17)
-
-#include "Globals.h"
-#include "M17TX.h"
-
-#include "M17Defines.h"
-
-// Generated using rcosdesign(0.5, 8, 5, 'sqrt') in MATLAB
-static q15_t RRC_0_5_FILTER[] = {0, 0, 0, 0, -290, -174, 142, 432, 438, 90, -387, -561, -155, 658, 1225, 767,
-				  -980, -3326, -4648, -3062, 2527, 11552, 21705, 29724, 32767, 29724, 21705,
-				  11552, 2527, -3062, -4648, -3326, -980, 767, 1225, 658, -155, -561, -387, 90,
-				  438, 432, 142, -174, -290}; // numTaps = 45, L = 5
-const uint16_t RRC_0_5_FILTER_PHASE_LEN = 9U; // phaseLength = numTaps/L
-
-const q15_t M17_LEVELA =  1481;
-const q15_t M17_LEVELB =  494;
-const q15_t M17_LEVELC = -494;
-const q15_t M17_LEVELD = -1481;
-
-const uint8_t M17_START_SYNC = 0x77U;
-const uint8_t M17_END_SYNC   = 0xFFU;
-const uint8_t M17_HANG       = 0x00U;
-
-CM17TX::CM17TX() :
-m_buffer(TX_BUFFER_LEN),
-m_modFilter(),
-m_modState(),
-m_poBuffer(),
-m_poLen(0U),
-m_poPtr(0U),
-m_txDelay(240U),      // 200ms
-m_txHang(4800U),      // 4s
-m_txCount(0U)
-{
-  ::memset(m_modState, 0x00U, 16U * sizeof(q15_t));
-
-  m_modFilter.L           = M17_RADIO_SYMBOL_LENGTH;
-  m_modFilter.phaseLength = RRC_0_5_FILTER_PHASE_LEN;
-  m_modFilter.pCoeffs     = RRC_0_5_FILTER;
-  m_modFilter.pState      = m_modState;
-}
-
-void CM17TX::process()
-{
-  // If we have M17 data to transmit, do so.
-  if (m_poLen == 0U && m_buffer.getData() > 0U) {
-    if (!m_tx) {
-      for (uint16_t i = 0U; i < m_txDelay; i++)
-        m_poBuffer[m_poLen++] = M17_START_SYNC;
-    } else {
-      for (uint8_t i = 0U; i < M17_FRAME_LENGTH_BYTES; i++) {
-        uint8_t c = 0U;
-        m_buffer.get(c);
-        m_poBuffer[m_poLen++] = c;
-      }
-    }
-
-    m_poPtr = 0U;
-  }
-
-  if (m_poLen > 0U) {
-    // Transmit M17 data.
-    uint16_t space = io.getSpace();
-
-    while (space > (4U * M17_RADIO_SYMBOL_LENGTH)) {
-      uint8_t c = m_poBuffer[m_poPtr++];
-      writeByte(c);
-
-      // Reduce space and reset the hang timer.
-      space -= 4U * M17_RADIO_SYMBOL_LENGTH;
-      if (m_duplex)
-        m_txCount = m_txHang;
-
-      if (m_poPtr >= m_poLen) {
-        m_poPtr = 0U;
-        m_poLen = 0U;
-        return;
-      }
-    }
-  } else if (m_txCount > 0U) {
-    // Transmit silence until the hang timer has expired.
-    uint16_t space = io.getSpace();
-
-    while (space > (4U * M17_RADIO_SYMBOL_LENGTH)) {
-      writeSilence();
-
-      space -= 4U * M17_RADIO_SYMBOL_LENGTH;
-      m_txCount--;
-
-      if (m_txCount == 0U)
-        return;
-    }
-  }
-}
-
-uint8_t CM17TX::writeData(const uint8_t* data, uint8_t length)
-{
-  if (length != (M17_FRAME_LENGTH_BYTES + 1U))
-    return 4U;
-
-  uint16_t space = m_buffer.getSpace();
-  if (space < M17_FRAME_LENGTH_BYTES)
-    return 5U;
-
-  for (uint8_t i = 0U; i < M17_FRAME_LENGTH_BYTES; i++)
-    m_buffer.put(data[i + 1U]);
-
-  return 0U;
-}
-
-void CM17TX::writeByte(uint8_t c)
-{
-  q15_t inBuffer[4U];
-  q15_t outBuffer[M17_RADIO_SYMBOL_LENGTH * 4U];
-
-  const uint8_t MASK = 0xC0U;
-
-  for (uint8_t i = 0U; i < 4U; i++, c <<= 2) {
-    switch (c & MASK) {
-      case 0xC0U:
-        inBuffer[i] = M17_LEVELA;
-        break;
-      case 0x80U:
-        inBuffer[i] = M17_LEVELB;
-        break;
-      case 0x00U:
-        inBuffer[i] = M17_LEVELC;
-        break;
-      default:
-        inBuffer[i] = M17_LEVELD;
-        break;
-    }
-  }
-
-  ::arm_fir_interpolate_q15(&m_modFilter, inBuffer, outBuffer, 4U);
-
-  io.write(STATE_M17, outBuffer, M17_RADIO_SYMBOL_LENGTH * 4U);
-}
-
-void CM17TX::writeSilence()
-{
-  q15_t inBuffer[4U] = {0, 0, 0, 0};
-  q15_t outBuffer[M17_RADIO_SYMBOL_LENGTH * 4U];
-
-  ::arm_fir_interpolate_q15(&m_modFilter, inBuffer, outBuffer, 4U);
-
-  io.write(STATE_M17, outBuffer, M17_RADIO_SYMBOL_LENGTH * 4U);
-}
-
-void CM17TX::setTXDelay(uint8_t delay)
-{
-  m_txDelay = 600U + uint16_t(delay) * 12U;        // 500ms + tx delay
-
-  if (m_txDelay > 1200U)
-    m_txDelay = 1200U;
-}
-
-uint8_t CM17TX::getSpace() const
-{
-  return m_buffer.getSpace() / M17_FRAME_LENGTH_BYTES;
-}
-
-void CM17TX::setParams(uint8_t txHang)
-{
-  m_txHang = txHang * 1200U;
-}
-
-#endif
-
@@ -1,60 +0,0 @@
-/*
- *   Copyright (C) 2015,2016,2017,2020 by Jonathan Naylor G4KLX
- *
- *   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"
-
-#if defined(MODE_M17)
-
-#if !defined(M17TX_H)
-#define  M17TX_H
-
-#include "RingBuffer.h"
-
-class CM17TX {
-public:
-  CM17TX();
-
-  uint8_t writeData(const uint8_t* data, uint8_t length);
-
-  void process();
-
-  void setTXDelay(uint8_t delay);
-
-  uint8_t getSpace() const;
-
-  void setParams(uint8_t txHang);
-
-private:
-  CRingBuffer<uint8_t>             m_buffer;
-  arm_fir_interpolate_instance_q15 m_modFilter;
-  q15_t                            m_modState[16U];    // blockSize + phaseLength - 1, 4 + 9 - 1 plus some spare
-  uint8_t                          m_poBuffer[1200U];
-  uint16_t                         m_poLen;
-  uint16_t                         m_poPtr;
-  uint16_t                         m_txDelay;
-  uint32_t                         m_txHang;
-  uint32_t                         m_txCount;
-
-  void writeByte(uint8_t c);
-  void writeSilence();
-};
-
-#endif
-
-#endif
-
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017,2018,2020,2021 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2018,2020,2021,2025 by Jonathan Naylor G4KLX
 *   Copyright (C) 2016 by Mathis Schmieder DB9MAT
 *   Copyright (C) 2016 by Colin Durbridge G4EML
 *
@@ -31,10 +31,8 @@ bool m_dmrEnable    = true;
 bool m_ysfEnable    = true;
 bool m_p25Enable    = true;
 bool m_nxdnEnable   = true;
-bool m_m17Enable    = true;
 bool m_pocsagEnable = true;
 bool m_fmEnable     = true;
-bool m_ax25Enable   = true;

 bool m_duplex = true;

@@ -79,13 +77,6 @@ CNXDNTX nxdnTX;
 CCalNXDN calNXDN;
 #endif

-#if defined(MODE_M17)
-CM17RX m17RX;
-CM17TX m17TX;
-
-CCalM17 calM17;
-#endif
-
 #if defined(MODE_POCSAG)
 CPOCSAGTX  pocsagTX;
 CCalPOCSAG calPOCSAG;
@@ -96,11 +87,6 @@ CFM    fm;
 CCalFM calFM;
 #endif

-#if defined(MODE_AX25)
-CAX25RX ax25RX;
-CAX25TX ax25TX;
-#endif
-
 CCalRSSI calRSSI;

 CCWIdTX cwIdTX;
@@ -149,21 +135,11 @@ void loop()
    nxdnTX.process();
 #endif

-#if defined(MODE_M17)
-  if (m_m17Enable && m_modemState == STATE_M17)
-    m17TX.process();
-#endif
-
 #if defined(MODE_POCSAG)
  if (m_pocsagEnable && (m_modemState == STATE_POCSAG || pocsagTX.busy()))
    pocsagTX.process();
 #endif

-#if defined(MODE_AX25)
-  if (m_ax25Enable && (m_modemState == STATE_IDLE || m_modemState == STATE_FM))
-    ax25TX.process();
-#endif
-
 #if defined(MODE_FM)
  if (m_fmEnable && m_modemState == STATE_FM)
    fm.process();
@@ -194,11 +170,6 @@ void loop()
    calNXDN.process();
 #endif

-#if defined(MODE_M17)
-  if (m_modemState == STATE_M17CAL)
-    calM17.process();
-#endif
-
 #if defined(MODE_POCSAG)
  if (m_modemState == STATE_POCSAGCAL)
    calPOCSAG.process();
@@ -217,3 +188,4 @@ int main()
 }

 #endif
+
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017,2018,2020,2021 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2018,2020,2021,2025 by Jonathan Naylor G4KLX
 *   Copyright (C) 2016 by Colin Durbridge G4EML
 *
 *   This program is free software; you can redistribute it and/or modify
@@ -28,10 +28,8 @@ bool m_dmrEnable    = true;
 bool m_ysfEnable    = true;
 bool m_p25Enable    = true;
 bool m_nxdnEnable   = true;
-bool m_m17Enable    = true;
 bool m_pocsagEnable = true;
 bool m_fmEnable     = true;
-bool m_ax25Enable   = true;

 bool m_duplex = true;

@@ -76,13 +74,6 @@ CNXDNTX nxdnTX;
 CCalNXDN calNXDN;
 #endif

-#if defined(MODE_M17)
-CM17RX m17RX;
-CM17TX m17TX;
-
-CCalM17 calM17;
-#endif
-
 #if defined(MODE_POCSAG)
 CPOCSAGTX  pocsagTX;
 CCalPOCSAG calPOCSAG;
@@ -93,11 +84,6 @@ CFM    fm;
 CCalFM calFM;
 #endif

-#if defined(MODE_AX25)
-CAX25RX ax25RX;
-CAX25TX ax25TX;
-#endif
-
 CCalRSSI calRSSI;

 CCWIdTX cwIdTX;
@@ -146,21 +132,11 @@ void loop()
    nxdnTX.process();
 #endif

-#if defined(MODE_M17)
-  if (m_m17Enable && m_modemState == STATE_M17)
-    m17TX.process();
-#endif
-
 #if defined(MODE_POCSAG)
  if (m_pocsagEnable && (m_modemState == STATE_POCSAG || pocsagTX.busy()))
    pocsagTX.process();
 #endif

-#if defined(MODE_AX25)
-  if (m_ax25Enable && (m_modemState == STATE_IDLE || m_modemState == STATE_FM))
-    ax25TX.process();
-#endif
-
 #if defined(MODE_FM)
  if (m_fmEnable && m_modemState == STATE_FM)
    fm.process();
@@ -191,11 +167,6 @@ void loop()
    calNXDN.process();
 #endif

-#if defined(MODE_M17)
-  if (m_modemState == STATE_M17CAL)
-    calM17.process();
-#endif
-
 #if defined(MODE_POCSAG)
  if (m_modemState == STATE_POCSAGCAL)
    calPOCSAG.process();
@@ -149,9 +149,9 @@ DEFS_EDA_446=-DUSE_STDPERIPH_DRIVER -DSTM32F4XX -DSTM32F446xx -DSTM32F4_EDA_446

 # Build compiler flags
 CFLAGS_F4=-c $(MCFLAGS_F4) $(INCLUDES_F4)
-CXXFLAGS_F4=-c $(MCFLAGS_F4) $(INCLUDES_F4)
+CXXFLAGS_F4=-c $(MCFLAGS_F4) $(INCLUDES_F4) -std=c++11
 CFLAGS_F7=-c $(MCFLAGS_F7) $(INCLUDES_F7)
-CXXFLAGS_F7=-c $(MCFLAGS_F7) $(INCLUDES_F7)
+CXXFLAGS_F7=-c $(MCFLAGS_F7) $(INCLUDES_F7) -std=c++11

 # Linker flags
 LDFLAGS_F4 =-T stm32f4xx_link.ld $(MCFLAGS_F4) --specs=nosys.specs $(INCLUDES_LIBS_F4)
@@ -1,4 +1,4 @@
-This is the source code of the MMDVM firmware that supports D-Star, DMR, System Fusion, P25, NXDN, M17, POCSAG, AX.25, and FM modes.
+This is the source code of the MMDVM firmware that supports D-Star, DMR, System Fusion, P25, NXDN, POCSAG, and FM modes.

 It runs on the Arduino Due, the ST-Micro STM32F4xxx and STM32F7xxx processors, as well as the Teensy 3.5/3.6. What these platforms have in common is the use of an ARM Cortex-M3, M4, or M7 processors with a minimum clock speed greater of 80 MHz, and access to at least one analogue to digital converter, one digital to analogue converter, as well as a number of GPIO pins.

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2020,2026 by Jonathan Naylor G4KLX
 *   Copyright (C) 2020 by Geoffrey Merck F4FXL - KC3FRA
 *
 *   This program is free software; you can redistribute it and/or modify
@@ -50,7 +50,7 @@ public:
  
  uint16_t getData() const;

-  bool put(TDATATYPE item) volatile;
+  bool put(const TDATATYPE& item) volatile;

  bool get(TDATATYPE& item) volatile;

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2020,2026 by Jonathan Naylor G4KLX
 *   Copyright (C) 2020 by Geoffrey Merck F4FXL - KC3FRA
 *
 *   This program is free software; you can redistribute it and/or modify
@@ -56,7 +56,7 @@ template <typename TDATATYPE> uint16_t CRingBuffer<TDATATYPE>::getData() const
    return m_length - m_tail + m_head;
 }

-template <typename TDATATYPE> bool CRingBuffer<TDATATYPE>::put(TDATATYPE item) volatile
+template <typename TDATATYPE> bool CRingBuffer<TDATATYPE>::put(const TDATATYPE& item) volatile
 {
  if (m_full) {
    m_overflow = true;
@@ -61,7 +61,7 @@ void CSTMUART::handleIRQ()
  if (USART_GetITStatus(m_usart, USART_IT_RXNE)) {
    if(!m_rxFifo.isFull())
      m_rxFifo.put((uint8_t) USART_ReceiveData(m_usart));
-    USART_ClearITPendingBit(USART1, USART_IT_RXNE);
+    USART_ClearITPendingBit(m_usart, USART_IT_RXNE);
  }

  if (USART_GetITStatus(m_usart, USART_IT_TXE)) {
@@ -82,8 +82,12 @@ void CSTMUART::flush()
  if(m_usart == NULL)
    return;

-   // wait until the TXE shows the shift register is empty
-   while (USART_GetITStatus(m_usart, USART_FLAG_TXE))
+   // wait until the TX FIFO has drained
+   while (!m_txFifo.isEmpty())
+      ;
+
+   // wait until the TC flag shows the shift register is empty
+   while (USART_GetFlagStatus(m_usart, USART_FLAG_TC) == RESET)
      ;
 }

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2013,2015-2021,2023 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2013,2015-2021,2023,2025 by Jonathan Naylor G4KLX
 *   Copyright (C) 2016 by Colin Durbridge G4EML
 *
 *   This program is free software; you can redistribute it and/or modify
@@ -45,6 +45,7 @@ const uint8_t MMDVM_DSTAR_DATA   = 0x11U;
 const uint8_t MMDVM_DSTAR_LOST   = 0x12U;
 const uint8_t MMDVM_DSTAR_EOT    = 0x13U;

+const uint8_t MMDVM_DMR_ALOHA    = 0x17U;
 const uint8_t MMDVM_DMR_DATA1    = 0x18U;
 const uint8_t MMDVM_DMR_LOST1    = 0x19U;
 const uint8_t MMDVM_DMR_DATA2    = 0x1AU;
@@ -63,17 +64,8 @@ const uint8_t MMDVM_P25_LOST     = 0x32U;
 const uint8_t MMDVM_NXDN_DATA    = 0x40U;
 const uint8_t MMDVM_NXDN_LOST    = 0x41U;

-const uint8_t MMDVM_M17_LINK_SETUP = 0x45U;
-const uint8_t MMDVM_M17_STREAM     = 0x46U;
-const uint8_t MMDVM_M17_PACKET     = 0x47U;
-const uint8_t MMDVM_M17_LOST       = 0x48U;
-const uint8_t MMDVM_M17_EOT        = 0x49U;
-
 const uint8_t MMDVM_POCSAG_DATA  = 0x50U;

-const uint8_t MMDVM_AX25_DATA    = 0x55U;
-const uint8_t MMDVM_AX25_DATA_EX = 0x56U;
-
 const uint8_t MMDVM_FM_PARAMS1   = 0x60U;
 const uint8_t MMDVM_FM_PARAMS2   = 0x61U;
 const uint8_t MMDVM_FM_PARAMS3   = 0x62U;
@@ -264,14 +256,7 @@ void CSerialPort::getStatus()
  reply[11U] = 0U;
 #endif

-#if defined(MODE_M17)
-  if (m_m17Enable)
-    reply[12U] = m17TX.getSpace();
-  else
-    reply[12U] = 0U;
-#else
  reply[12U] = 0U;
-#endif

 #if defined(MODE_FM)
  if (m_fmEnable)
@@ -291,15 +276,7 @@ void CSerialPort::getStatus()
  reply[14U] = 0U;
 #endif

-#if defined(MODE_AX25)
-  if (m_ax25Enable)
-    reply[15U] = ax25TX.getSpace();
-  else
-    reply[15U] = 0U;
-#else
  reply[15U] = 0U;
-#endif
-
  reply[16U] = 0x00U;
  reply[17U] = 0x00U;
  reply[18U] = 0x00U;
@@ -335,9 +312,6 @@ void CSerialPort::getVersion()
 #if defined(MODE_NXDN)
  reply[4U] |= 0x10U;
 #endif
-#if defined(MODE_M17)
-  reply[4U] |= 0x20U;
-#endif
 #if defined(MODE_FM)
  reply[4U] |= 0x40U;
 #endif
@@ -346,9 +320,6 @@ void CSerialPort::getVersion()
 #if defined(MODE_POCSAG)
  reply[5U] |= 0x01U;
 #endif
-#if defined(MODE_AX25)
-  reply[5U] |= 0x02U;
-#endif

  // CPU type/manufacturer. 0=Atmel ARM, 1=NXP ARM, 2=St-Micro ARM
  reply[6U] = io.getCPU();
@@ -400,15 +371,9 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint16_t length)
 #if defined(MODE_FM)
  bool fmEnable     = (data[1U] & 0x20U) == 0x20U;
 #endif
-#if defined(MODE_M17)
-  bool m17Enable    = (data[1U] & 0x40U) == 0x40U;
-#endif
 #if defined(MODE_POCSAG)
  bool pocsagEnable = (data[2U] & 0x01U) == 0x01U;
 #endif
-#if defined(MODE_AX25)
-  bool ax25Enable   = (data[2U] & 0x02U) == 0x02U;
-#endif

  uint8_t txDelay = data[3U];
  if (txDelay > 50U)
@@ -416,8 +381,8 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint16_t length)

  MMDVM_STATE modemState = MMDVM_STATE(data[4U]);

-  if (modemState != STATE_IDLE && modemState != STATE_DSTAR && modemState != STATE_DMR && modemState != STATE_YSF && modemState != STATE_P25 && modemState != STATE_NXDN && modemState != STATE_M17 && modemState != STATE_POCSAG && modemState != STATE_FM &&
-      modemState != STATE_DSTARCAL && modemState != STATE_DMRCAL && modemState != STATE_RSSICAL && modemState != STATE_LFCAL && modemState != STATE_DMRCAL1K && modemState != STATE_P25CAL1K && modemState != STATE_DMRDMO1K && modemState != STATE_NXDNCAL1K && modemState != STATE_M17CAL && modemState != STATE_POCSAGCAL &&
+  if (modemState != STATE_IDLE && modemState != STATE_DSTAR && modemState != STATE_DMR && modemState != STATE_YSF && modemState != STATE_P25 && modemState != STATE_NXDN && modemState != STATE_POCSAG && modemState != STATE_FM &&
+      modemState != STATE_DSTARCAL && modemState != STATE_DMRCAL && modemState != STATE_RSSICAL && modemState != STATE_LFCAL && modemState != STATE_DMRCAL1K && modemState != STATE_P25CAL1K && modemState != STATE_DMRDMO1K && modemState != STATE_NXDNCAL1K && modemState != STATE_POCSAGCAL &&
      modemState != STATE_FMCAL10K && modemState != STATE_FMCAL12K && modemState != STATE_FMCAL15K && modemState != STATE_FMCAL20K && modemState != STATE_FMCAL25K && modemState != STATE_FMCAL30K)
    return 4U;

@@ -461,14 +426,6 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint16_t length)
    return 4U;
 #endif

-#if defined(MODE_M17)
-  if (modemState == STATE_M17 && !m17Enable)
-    return 4U;
-#else
-  if (modemState == STATE_M17)
-    return 4U;
-#endif
-
 #if defined(MODE_POCSAG)
  if (modemState == STATE_POCSAG && !pocsagEnable)
    return 4U;
@@ -496,10 +453,8 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint16_t length)
  uint8_t ysfTXLevel    = data[11U];
  uint8_t p25TXLevel    = data[12U];
  uint8_t nxdnTXLevel   = data[13U];
-  uint8_t m17TXLevel    = data[14U];
  uint8_t pocsagTXLevel = data[15U];
  uint8_t fmTXLevel     = data[16U];
-  uint8_t ax25TXLevel   = data[17U];

 #if defined(MODE_YSF)
  uint8_t ysfTXHang     = data[20U];
@@ -510,11 +465,9 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint16_t length)
 #if defined(MODE_NXDN)
  uint8_t nxdnTXHang    = data[22U];
 #endif
-#if defined(MODE_M17)
-  uint8_t m17TXHang     = data[23U];
-#endif

 #if defined(MODE_DMR)
+  bool trunking = (data[25U] & 128U) == 128U;
  uint8_t colorCode = data[26U];
  if (colorCode > 15U)
    return 4U;
@@ -522,16 +475,6 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint16_t length)
  uint8_t dmrDelay = data[27U];
 #endif

-#if defined(MODE_AX25)
-  int8_t ax25RXTwist    = int8_t(data[28U]) - 128;
-  if (ax25RXTwist < -4 || ax25RXTwist > 10)
-    return 4U;
-
-  uint8_t ax25TXDelay   = data[29U];
-  uint8_t ax25SlotTime  = data[30U];
-  uint8_t ax25PPersist  = data[31U];
-#endif
-
  setMode(modemState);

  m_duplex       = !simplex;
@@ -543,7 +486,7 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint16_t length)
 #if defined(MODE_DMR)
  m_dmrEnable    = dmrEnable;
  dmrDMOTX.setTXDelay(txDelay);
-
+  dmrTX.setTrunking(trunking);
  dmrTX.setColorCode(colorCode);
  dmrRX.setColorCode(colorCode);
  dmrRX.setDelay(dmrDelay);
@@ -565,25 +508,15 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint16_t length)
  nxdnTX.setTXDelay(txDelay);
  nxdnTX.setParams(nxdnTXHang);
 #endif
-#if defined(MODE_M17)
-  m_m17Enable    = m17Enable;
-  m17TX.setTXDelay(txDelay);
-  m17TX.setParams(m17TXHang);
-#endif
 #if defined(MODE_POCSAG)
  m_pocsagEnable = pocsagEnable;
  pocsagTX.setTXDelay(txDelay);
 #endif
-#if defined(MODE_AX25)
-  m_ax25Enable   = ax25Enable;
-  ax25TX.setTXDelay(ax25TXDelay);
-  ax25RX.setParams(ax25RXTwist, ax25SlotTime, ax25PPersist);
-#endif
 #if defined(MODE_FM)
  m_fmEnable     = fmEnable;
 #endif

-  io.setParameters(rxInvert, txInvert, pttInvert, rxLevel, cwIdTXLevel, dstarTXLevel, dmrTXLevel, ysfTXLevel, p25TXLevel, nxdnTXLevel, m17TXLevel, pocsagTXLevel, fmTXLevel, ax25TXLevel, txDCOffset, rxDCOffset, useCOSAsLockout);
+  io.setParameters(rxInvert, txInvert, pttInvert, rxLevel, cwIdTXLevel, dstarTXLevel, dmrTXLevel, ysfTXLevel, p25TXLevel, nxdnTXLevel, pocsagTXLevel, fmTXLevel, txDCOffset, rxDCOffset, useCOSAsLockout);

  io.start();

@@ -697,8 +630,8 @@ uint8_t CSerialPort::setMode(const uint8_t* data, uint16_t length)
  if (modemState == m_modemState)
    return 0U;

-  if (modemState != STATE_IDLE && modemState != STATE_DSTAR && modemState != STATE_DMR && modemState != STATE_YSF && modemState != STATE_P25 && modemState != STATE_NXDN && modemState != STATE_M17 && modemState != STATE_POCSAG && modemState != STATE_FM &&
-      modemState != STATE_DSTARCAL && modemState != STATE_DMRCAL && modemState != STATE_RSSICAL && modemState != STATE_LFCAL && modemState != STATE_DMRCAL1K && modemState != STATE_P25CAL1K && modemState != STATE_DMRDMO1K && modemState != STATE_NXDNCAL1K && modemState != STATE_M17CAL && modemState != STATE_POCSAGCAL &&
+  if (modemState != STATE_IDLE && modemState != STATE_DSTAR && modemState != STATE_DMR && modemState != STATE_YSF && modemState != STATE_P25 && modemState != STATE_NXDN && modemState != STATE_POCSAG && modemState != STATE_FM &&
+      modemState != STATE_DSTARCAL && modemState != STATE_DMRCAL && modemState != STATE_RSSICAL && modemState != STATE_LFCAL && modemState != STATE_DMRCAL1K && modemState != STATE_P25CAL1K && modemState != STATE_DMRDMO1K && modemState != STATE_NXDNCAL1K && modemState != STATE_POCSAGCAL &&
      modemState != STATE_FMCAL10K  && modemState != STATE_FMCAL12K && modemState != STATE_FMCAL15K && modemState != STATE_FMCAL20K && modemState != STATE_FMCAL25K && modemState != STATE_FMCAL30K)
    return 4U;

@@ -742,14 +675,6 @@ uint8_t CSerialPort::setMode(const uint8_t* data, uint16_t length)
    return 4U;
 #endif

-#if defined(MODE_M17)
-  if (modemState == STATE_M17 && !m_m17Enable)
-    return 4U;
-#else
-  if (modemState == STATE_M17)
-    return 4U;
-#endif
-
 #if defined(MODE_POCSAG)
  if (modemState == STATE_POCSAG && !m_pocsagEnable)
    return 4U;
@@ -789,9 +714,6 @@ void CSerialPort::setMode(MMDVM_STATE modemState)
    case STATE_NXDN:
      DEBUG1("Mode set to NXDN");
      break;
-    case STATE_M17:
-      DEBUG1("Mode set to M17");
-      break;
    case STATE_POCSAG:
      DEBUG1("Mode set to POCSAG");
      break;
@@ -823,7 +745,7 @@ void CSerialPort::setMode(MMDVM_STATE modemState)
      DEBUG1("Mode set to FM 20Khz Calibrate");
      break;
    case STATE_FMCAL25K:
-      DEBUG1("Mode set to FM 10Khz Calibrate");
+      DEBUG1("Mode set to FM 25Khz Calibrate");
      break;
    case STATE_FMCAL30K:
      DEBUG1("Mode set to FM 30Khz Calibrate");
@@ -840,9 +762,6 @@ void CSerialPort::setMode(MMDVM_STATE modemState)
    case STATE_POCSAGCAL:
      DEBUG1("Mode set to POCSAG Calibrate");
      break;
-    case STATE_M17CAL:
-      DEBUG1("Mode set to M17 Calibrate");
-      break;
    default:        // STATE_IDLE
      DEBUG1("Mode set to Idle");
      break;
@@ -876,11 +795,6 @@ void CSerialPort::setMode(MMDVM_STATE modemState)
    nxdnRX.reset();
 #endif

-#if defined(MODE_M17)
-  if (modemState != STATE_M17)
-    m17RX.reset();
-#endif
-
 #if defined(MODE_FM)
  if (modemState != STATE_FM)
    fm.reset();
@@ -1080,10 +994,6 @@ void CSerialPort::processMessage(uint8_t type, const uint8_t* buffer, uint16_t l
      if (m_modemState == STATE_NXDNCAL1K)
        err = calNXDN.write(buffer, length);
 #endif
-#if defined(MODE_M17)
-      if (m_modemState == STATE_M17CAL)
-        err = calM17.write(buffer, length);
-#endif
 #if defined(MODE_POCSAG)
      if (m_modemState == STATE_POCSAGCAL)
        err = calPOCSAG.write(buffer, length);
@@ -1215,6 +1125,15 @@ void CSerialPort::processMessage(uint8_t type, const uint8_t* buffer, uint16_t l
      }
      break;

+    case MMDVM_DMR_ALOHA:
+      if (m_dmrEnable)
+        err = dmrTX.writeAloha(buffer, length);
+      if (err != 0U) {
+        DEBUG2("Received invalid DMR ALOHA", err);
+        sendNAK(type, err);
+      }
+      break;
+
    case MMDVM_DMR_ABORT:
      if (m_dmrEnable)
        err = dmrTX.writeAbort(buffer, length);
@@ -1287,50 +1206,6 @@ void CSerialPort::processMessage(uint8_t type, const uint8_t* buffer, uint16_t l
      break;
 #endif

-#if defined(MODE_M17)
-    case MMDVM_M17_LINK_SETUP:
-      if (m_m17Enable) {
-        if (m_modemState == STATE_IDLE || m_modemState == STATE_M17)
-          err = m17TX.writeData(buffer, length);
-      }
-      if (err == 0U) {
-        if (m_modemState == STATE_IDLE)
-          setMode(STATE_M17);
-      } else {
-        DEBUG2("Received invalid M17 link setup data", err);
-        sendNAK(type, err);
-      }
-      break;
-
-    case MMDVM_M17_STREAM:
-      if (m_m17Enable) {
-        if (m_modemState == STATE_IDLE || m_modemState == STATE_M17)
-          err = m17TX.writeData(buffer, length);
-      }
-      if (err == 0U) {
-        if (m_modemState == STATE_IDLE)
-          setMode(STATE_M17);
-      } else {
-        DEBUG2("Received invalid M17 stream data", err);
-        sendNAK(type, err);
-      }
-      break;
-
-    case MMDVM_M17_EOT:
-      if (m_m17Enable) {
-        if (m_modemState == STATE_IDLE || m_modemState == STATE_M17)
-          err = m17TX.writeData(buffer, length);
-      }
-      if (err == 0U) {
-        if (m_modemState == STATE_IDLE)
-          setMode(STATE_M17);
-      } else {
-        DEBUG2("Received invalid M17 EOT", err);
-        sendNAK(type, err);
-      }
-      break;
-#endif
-
 #if defined(MODE_POCSAG)
    case MMDVM_POCSAG_DATA:
      if (m_pocsagEnable) {
@@ -1363,19 +1238,6 @@ void CSerialPort::processMessage(uint8_t type, const uint8_t* buffer, uint16_t l
      break;
 #endif

-#if defined(MODE_AX25)
-    case MMDVM_AX25_DATA:
-      if (m_ax25Enable) {
-        if (m_modemState == STATE_IDLE || m_modemState == STATE_FM)
-          err = ax25TX.writeData(buffer, length);
-      }
-      if (err != 0U) {
-        DEBUG2("Received invalid AX.25 data", err);
-        sendNAK(type, err);
-      }
-      break;
-#endif
-
    case MMDVM_TRANSPARENT:
    case MMDVM_QSO_INFO:
      // Do nothing on the MMDVM.
@@ -1675,88 +1537,6 @@ void CSerialPort::writeNXDNLost()
 }
 #endif

-#if defined(MODE_M17)
-void CSerialPort::writeM17LinkSetup(const uint8_t* data, uint8_t length)
-{
-  if (m_modemState != STATE_M17 && m_modemState != STATE_IDLE)
-    return;
-
-  if (!m_m17Enable)
-    return;
-
-  uint8_t reply[130U];
-
-  reply[0U] = MMDVM_FRAME_START;
-  reply[1U] = 0U;
-  reply[2U] = MMDVM_M17_LINK_SETUP;
-
-  uint8_t count = 3U;
-  for (uint8_t i = 0U; i < length; i++, count++)
-    reply[count] = data[i];
-
-  reply[1U] = count;
-
-  writeInt(1U, reply, count);
-}
-
-void CSerialPort::writeM17Stream(const uint8_t* data, uint8_t length)
-{
-  if (m_modemState != STATE_M17 && m_modemState != STATE_IDLE)
-    return;
-
-  if (!m_m17Enable)
-    return;
-
-  uint8_t reply[130U];
-
-  reply[0U] = MMDVM_FRAME_START;
-  reply[1U] = 0U;
-  reply[2U] = MMDVM_M17_STREAM;
-
-  uint8_t count = 3U;
-  for (uint8_t i = 0U; i < length; i++, count++)
-    reply[count] = data[i];
-
-  reply[1U] = count;
-
-  writeInt(1U, reply, count);
-}
-
-void CSerialPort::writeM17EOT()
-{
-  if (m_modemState != STATE_M17 && m_modemState != STATE_IDLE)
-    return;
-
-  if (!m_m17Enable)
-    return;
-
-  uint8_t reply[3U];
-
-  reply[0U] = MMDVM_FRAME_START;
-  reply[1U] = 3U;
-  reply[2U] = MMDVM_M17_EOT;
-
-  writeInt(1U, reply, 3);
-}
-
-void CSerialPort::writeM17Lost()
-{
-  if (m_modemState != STATE_M17 && m_modemState != STATE_IDLE)
-    return;
-
-  if (!m_m17Enable)
-    return;
-
-  uint8_t reply[3U];
-
-  reply[0U] = MMDVM_FRAME_START;
-  reply[1U] = 3U;
-  reply[2U] = MMDVM_M17_LOST;
-
-  writeInt(1U, reply, 3);
-}
-#endif
-
 #if defined(MODE_FM)
 void CSerialPort::writeFMData(const uint8_t* data, uint16_t length)
 {
@@ -1845,78 +1625,6 @@ void CSerialPort::writeFMEOT()
 }
 #endif

-#if defined(MODE_AX25)
-void CSerialPort::writeAX25Data(const uint8_t* data, uint16_t length)
-{
-  if (m_modemState != STATE_FM && m_modemState != STATE_IDLE)
-    return;
-
-  if (!m_ax25Enable)
-    return;
-
-  uint8_t reply[512U];
-
-  reply[0U] = MMDVM_FRAME_START;
-
-  if (length > 252U) {
-    reply[1U] = 0U;
-    reply[2U] = (length + 4U) - 255U;
-    reply[3U] = MMDVM_AX25_DATA;
-
-    for (uint16_t i = 0U; i < length; i++)
-      reply[i + 4U] = data[i];
-
-    writeInt(1U, reply, length + 4U);
-  } else {
-    reply[1U] = length + 3U;
-    reply[2U] = MMDVM_AX25_DATA;
-
-    for (uint16_t i = 0U; i < length; i++)
-      reply[i + 3U] = data[i];
-
-    writeInt(1U, reply, length + 3U);
-  }
-}
-
-void CSerialPort::writeAX25DataEx(uint16_t rssi, const uint8_t* data, uint16_t length)
-{
-  if (m_modemState != STATE_FM && m_modemState != STATE_IDLE)
-    return;
-
-  if (!m_ax25Enable)
-    return;
-
-  uint8_t reply[512U];
-
-  reply[0U] = MMDVM_FRAME_START;
-
-  if (length > 250U) {
-    reply[1U] = 0U;
-    reply[2U] = (length + 6U) - 255U;
-    reply[3U] = MMDVM_AX25_DATA_EX;
-
-    reply[4U] = (rssi >> 8) & 0xFFU;
-    reply[5U] = (rssi >> 0) & 0xFFU;
-  
-    for (uint16_t i = 0U; i < length; i++)
-      reply[i + 6U] = data[i];
-
-    writeInt(1U, reply, length + 6U);
-  } else {
-    reply[1U] = length + 5U;
-    reply[2U] = MMDVM_AX25_DATA_EX;
-
-    reply[3U] = (rssi >> 8) & 0xFFU;
-    reply[4U] = (rssi >> 0) & 0xFFU;
-  
-    for (uint16_t i = 0U; i < length; i++)
-      reply[i + 5U] = data[i];
-
-    writeInt(1U, reply, length + 5U);
-  }
-}
-#endif
-
 #if defined(SERIAL_REPEATER)
 void CSerialPort::writeSerialData(const uint8_t* data, uint8_t length)
 {
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017,2018,2020,2021,2023 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2018,2020,2021,2023,2025 by Jonathan Naylor G4KLX
 *
 *   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
@@ -64,18 +64,6 @@ public:
  void writeNXDNLost();
 #endif

-#if defined(MODE_M17)
-  void writeM17LinkSetup(const uint8_t* data, uint8_t length);
-  void writeM17Stream(const uint8_t* data, uint8_t length);
-  void writeM17Lost();
-  void writeM17EOT();
-#endif
-
-#if defined(MODE_AX25)
-  void writeAX25Data(const uint8_t* data, uint16_t length);
-  void writeAX25DataEx(uint16_t rssi, const uint8_t* data, uint16_t length);
-#endif
-
 #if defined(MODE_FM)
  void writeFMData(const uint8_t* data, uint16_t length);
  void writeFMStatus(uint8_t status);
@@ -134,3 +122,4 @@ private:
 };

 #endif
+
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2020,2021,2022,2023 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2020,2021,2022,2023,2025,2026 by Jonathan Naylor G4KLX
 *
 *   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
@@ -19,7 +19,6 @@
 #if !defined(VERSION_H)
 #define  VERSION_H

-#define VERSION "20230802"
+#define VERSION "20260424"

 #endif
-
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2017,2020 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2017,2020,2024 by Jonathan Naylor G4KLX
 *
 *   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
@@ -39,7 +39,7 @@ const uint8_t NOAVEPTR = 99U;

 const uint16_t NOENDPTR = 9999U;

-const unsigned int MAX_SYNC_FRAMES = 1U + 1U;
+const unsigned int MAX_SYNC_FRAMES = 4U + 1U;

 CYSFRX::CYSFRX() :
 m_state(YSFRXS_NONE),
Author	SHA1	Message	Date
Jonathan Naylor	046e1df161	Merge pull request #362 from n0mjs710/link-audio-fidelity FM link-mode network audio: anti-alias/reconstruction filtering	2026-08-16 17:36:20 +01:00
Cort Buffington	d70ab85bae	Copy-construct the ds/us filters from m_filterStage1/2/3 Same coefficients, no need to retype them. CFMDirectFormI's copy ctor already copies coefficients and (zeroed, at this point) state.	2026-08-13 13:52:06 -05:00
Cort Buffington	384c5d559d	Reconstruction filter after ext-audio upsampling in FM mode CFMUpSampler zero-stuffs 8kHz to 24kHz with no lowpass after it, leaving imaging artifacts in the reconstructed ext audio. Filter it with a second, separately-stated pass of the same 300-2700Hz design already used for TX shaping, right where it comes out of the upsampler.	2026-08-12 07:43:23 -05:00
Cort Buffington	4c7e8fbe46	Anti-alias filter before RF->network downsampling in FM mode The 24kHz->8kHz decimation in CFMDownSampler had no lowpass ahead of it, aliasing everything above 4kHz back into the audio band. Reuse the existing 300-2700Hz filter design (separate instance/state) ahead of all three addSample() call sites in FM.cpp. Also: reset() wasn't clearing the ring buffer or in-progress sample pack, so stale audio could bleed into the next transmission. And addSample() packed samples into 12 bits with no saturation, so an out-of-range value corrupted the neighbouring sample.	2026-08-11 09:57:47 -05:00
Jonathan Naylor	894ba76432	Merge pull request #361 from n0mjs710/link-mode-ext-gap Link mode ext audio gap	2026-08-11 15:02:32 +01:00
Cort Buffington	8a89804fda	Refactor FM_LINK_EXT_GAP_MS and improve comments Updated the FM_LINK_EXT_GAP_MS constant declaration and added comments for clarity.	2026-08-11 08:55:22 -05:00
Cort Buffington	8bd467598c	Debounce link-mode external-audio underrun before dropping PTT Under [FM] LinkMode=1, linkStateMachine() set m_extSignal false the instant a single ext-audio sample went missing, with no debounce -- unlike the non-link duplex/simplex paths, which already tolerate a brief gap via the RELAYING_EXT -> RELAYING_WAIT_EXT / m_ackDelayTimer pattern before declaring a real loss. Since IO::process() drops PTT the moment the downstream TX buffer runs dry, that zero-debounce cutoff meant even a very brief, late-but-recoverable gap from the gateway (scheduling jitter, a late UDP frame, etc.) could cascade into a full PTT drop-and-rekey cycle -- far more audible than the underlying gap itself. Adds m_extGapTimer, mirroring the existing pattern: on the first missed sample, start the timer instead of immediately clearing m_extSignal; a gap that recovers before FM_LINK_EXT_GAP_MS (default 60ms) expires never affects m_extSignal at all, so the transmitter never notices. Only a gap that outlasts the timer is treated as a genuine end of transmission, exactly as before. linkSamples()'s currentExtSample is now zero-initialized, since m_extSignal can now stay true for a few samples past an underrun -- silence, not stack garbage, must be what gets played out to the modem during that window.	2026-08-09 11:42:20 -05:00
Jonathan Naylor	715d3f5839	Merge pull request #359 from chancellor1101/bugfixes Fix several small bugs: STM UART repeater port, FM noise squelch, Due FM LED, DMR trunking state	2026-07-13 12:07:39 +01:00
Clint Chance	68252f15f5	Fix the FM 25kHz calibration debug message. It said 10kHz, a copy and paste from the case above.	2026-07-12 16:45:24 -05:00
Clint Chance	96061a6013	Make DMR trunking state handling order-independent. The CSBK slot type was only encoded into the ALOHA frame inside setColorCode(), so it took effect only if a reconfigure happened after an ALOHA frame had already been received; on the usual command ordering (SET_CONFIG then ALOHA) the transmitted slot type depended entirely on the host-supplied bytes. Remember the colour code and stamp the slot type in writeAloha() as well. Also clear m_controlChannel when trunking is disabled, so the host has a way to stop control channel transmission other than rebooting, and fix a stray tab introduced in createCACH().	2026-07-12 16:45:24 -05:00
Clint Chance	90220cbb9d	Fix the FM mode LED pin guard on the Arduino Due. The pinMode() call for PIN_FM was guarded by USE_ALTERNATE_POCSAG_LEDS instead of USE_ALTERNATE_FM_LEDS, a copy and paste error. The Teensy version and the setFMInt() implementation in this file both use the FM macro.	2026-07-12 16:42:58 -05:00
Clint Chance	2eb6f7fd06	Initialise and reset the FM noise squelch invalid counter. m_invalidCount was missing from the constructor initialiser list and was read uninitialised in process(), making the squelch behaviour after power-up indeterminate. reset() also cleared neither hysteresis counter, so state leaked across squelch resets.	2026-07-12 16:42:58 -05:00
Clint Chance	a1794b44ed	Fix RX interrupt flag being cleared on the wrong USART in STMUART. handleIRQ() hardcoded USART1 when clearing the RXNE pending bit, so on boards where the repeater/display UART is not USART1 (Nucleo, Discovery, F767, UART5-based boards) the flag was cleared on the wrong peripheral. Use the m_usart member, matching the TXE handling below. Also fix flush(): it passed a flag constant to USART_GetITStatus and span while TXE was set, which returns immediately since TXE indicates the data register is already empty. Wait for the software TX FIFO to drain and then for the TC flag, which indicates the shift register has actually emptied.	2026-07-12 16:42:47 -05:00
Jonathan Naylor	57e692ad8c	Small cleanups of the DMR trunking code.	2026-04-24 16:54:23 +01:00
Jonathan Naylor	841d7505c2	Merge pull request #358 from qradiolink/trunking_patches Add support for DMR tier III trunking	2026-04-24 14:50:28 +01:00
adrian	549dfd7258	Change DMR ALOHA header to 0x17	2026-04-19 11:32:07 +03:00
adrian	30ba4c4c55	Fix merge gone wrong in DMRTX.cpp	2026-04-19 11:12:37 +03:00
adrian	a696fd454c	DMR trunking patches to DMRTX and SerialPort	2026-04-18 11:29:48 +03:00
Jonathan Naylor	3fd84d5ed4	Fix merge compilation issue.	2026-02-19 15:59:46 +00:00
Jonathan Naylor	78216afbb7	Clean up the ring buffer.	2026-02-18 13:40:05 +00:00
Jonathan Naylor	0308bfc6c7	Merge branch 'master' into mqtt	2026-02-18 13:36:22 +00:00
Jonathan Naylor	278c69152a	Merge pull request #356 from F4FXL/C++11-Flags	2026-01-20 20:31:18 +00:00
Geoffrey Merck	8e144e81d0	Add C++11 standard flag to compiler flags Debian Trixie ships with arm-none-eabi-g++ v14.2.1 which defaults to c++17, this forces compilation with c++11	2026-01-20 20:29:04 +01:00
Jonathan Naylor	5dd59fc473	Merge branch 'master' into mqtt	2025-08-28 17:00:21 +01:00
Jonathan Naylor	5fb5986d50	Remove M17 and AX.25	2025-08-27 18:35:30 +01:00
Jonathan Naylor	824c9b9852	Widened the size of serial data going into M17 and FM.	2025-01-13 15:05:28 +00:00
Jonathan Naylor	f324f96db7	Increase the number of frames before YSF declares a signal to be lost.	2024-11-21 17:50:15 +00:00