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Merge pull request #361 from n0mjs710/link-mode-ext-gap 

Link mode ext audio gap
This commit is contained in:
Jonathan Naylor 2026-08-11 15:02:32 +01:00 committed by GitHub
parent 715d3f5839 8a89804fda
commit 894ba76432
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GPG Key ID: B5690EEEBB952194
2 changed files with 37 additions and 10 deletions
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32
FM.cpp
View File

@ -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;
@ -62,6 +63,7 @@ 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),
@ -85,6 +87,7 @@ m_rssiAccum(0U),
m_rssiCount(0U)
{
m_reverseTimer.setTimeout(0U, 150U);
m_extGapTimer.setTimeout(0U, FM_LINK_EXT_GAP_MS);
insertDelay(100U);
}
@ -250,13 +253,15 @@ 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
inputExt = inputExt && m_extEnabled;
@ -601,6 +606,7 @@ 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 +1237,12 @@ 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);
@ -1248,6 +1260,18 @@ void CFM::linkStateMachine(bool validRFSignal, bool validExtSignal)
}
if (!validExtSignal && m_extSignal) {
// 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;
@ -1256,6 +1280,8 @@ void CFM::linkStateMachine(bool validRFSignal, bool validExtSignal)
m_needReverse = true;
m_extSignal = false;
m_extGapTimer.stop();
}
}
}

1
FM.h
View File

@ -75,6 +75,7 @@ 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;