Files
MMDVM/FM.h
T
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

146 lines
5.4 KiB
C++

/*
* 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
* 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_FM)
#if !defined(FM_H)
#define FM_H
#include "FMBlanking.h"
#include "FMCTCSSRX.h"
#include "FMCTCSSTX.h"
#include "FMTimeout.h"
#include "FMKeyer.h"
#include "FMTimer.h"
#include "RingBuffer.h"
#include "FMDirectForm1.h"
#include "FMDownSampler.h"
#include "FMUpSampler.h"
#include "FMNoiseSquelch.h"
class CFM {
public:
CFM();
void samples(bool cos, q15_t* samples, const uint16_t* rssi, uint8_t length);
void process();
void reset();
uint8_t setCallsign(const char* callsign, uint8_t speed, uint16_t frequency, uint8_t time, uint8_t holdoff, uint8_t highLevel, uint8_t lowLevel, bool callsignAtStart, bool callsignAtEnd, bool callsignAtLatch);
uint8_t setAck(const char* rfAck, uint8_t speed, uint16_t frequency, uint8_t minTime, uint16_t delay, uint8_t level);
uint8_t setMisc(uint16_t timeout, uint8_t timeoutLevel, uint8_t ctcssFrequency, uint8_t ctcssHighThreshold, uint8_t ctcssLowThreshold, uint8_t ctcssLevel, uint8_t kerchunkTime, uint8_t hangTime, uint8_t accessMode, bool linkMode, bool cosInvert, bool noiseSquelch, uint8_t squelchHighThreshold, uint8_t squelchLowThreshold, uint8_t rfAudioBoost, uint8_t maxDev, uint8_t rxLevel);
uint8_t setExt(const char* ack, uint8_t audioBoost, uint8_t speed, uint16_t frequency, uint8_t level);
uint8_t getSpace() const;
uint8_t writeData(const uint8_t* data, uint16_t length);
private:
CFMKeyer m_callsign;
CFMKeyer m_rfAck;
CFMKeyer m_extAck;
CFMCTCSSRX m_ctcssRX;
CFMCTCSSTX m_ctcssTX;
CFMNoiseSquelch m_squelch;
CFMTimeout m_timeoutTone;
uint8_t m_state;
bool m_callsignAtStart;
bool m_callsignAtEnd;
bool m_callsignAtLatch;
CFMTimer m_callsignTimer;
CFMTimer m_timeoutTimer;
CFMTimer m_holdoffTimer;
CFMTimer m_kerchunkTimer;
CFMTimer m_ackMinTimer;
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;
CFMBlanking m_blanking;
uint8_t m_accessMode;
bool m_linkMode;
bool m_cosInvert;
bool m_noiseSquelch;
q15_t m_rfAudioBoost;
q15_t m_extAudioBoost;
CFMDownSampler m_downSampler;
bool m_extEnabled;
q15_t m_rxLevel;
CRingBuffer<q15_t> m_inputRFRB;
CRingBuffer<q15_t> m_outputRFRB;
CFMUpSampler m_inputExtRB;
bool m_rfSignal;
bool m_extSignal;
uint32_t m_rssiAccum;
uint16_t m_rssiCount;
void stateMachine(bool validRFSignal, bool validExtSignal);
void repeaterSamples(bool cos, q15_t* samples, const uint16_t* rssi, uint8_t length);
void linkSamples(bool cos, q15_t* samples, uint8_t length);
void duplexStateMachine(bool validRFSignal, bool validExtSignal);
void listeningStateDuplex(bool validRFSignal, bool validExtSignal);
void kerchunkRFStateDuplex(bool validSignal);
void relayingRFStateDuplex(bool validSignal);
void relayingRFWaitStateDuplex(bool validSignal);
void timeoutRFStateDuplex(bool validSignal);
void timeoutRFWaitStateDuplex(bool validSignal);
void kerchunkExtStateDuplex(bool validSignal);
void relayingExtStateDuplex(bool validSignal);
void relayingExtWaitStateDuplex(bool validSignal);
void timeoutExtStateDuplex(bool validSignal);
void timeoutExtWaitStateDuplex(bool validSignal);
void hangStateDuplex(bool validRFSignal, bool validExtSignal);
void simplexStateMachine(bool validRFSignal, bool validExtSignal);
void listeningStateSimplex(bool validRFSignal, bool validExtSignal);
void relayingRFStateSimplex(bool validSignal);
void relayingRFWaitStateSimplex(bool validSignal);
void timeoutRFStateSimplex(bool validSignal);
void timeoutRFWaitStateSimplex(bool validSignal);
void relayingExtStateSimplex(bool validSignal);
void relayingExtWaitStateSimplex(bool validSignal);
void timeoutExtStateSimplex(bool validSignal);
void timeoutExtWaitStateSimplex(bool validSignal);
void linkStateMachine(bool validRFSignal, bool validExtSignal);
void clock(uint8_t length);
void sendCallsign();
void beginRelaying();
void insertDelay(uint16_t ms);
void insertSilence(uint16_t ms);
};
#endif
#endif