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Refactor FM_LINK_EXT_GAP_MS and improve comments 

Updated the FM_LINK_EXT_GAP_MS constant declaration and added comments for clarity.
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Cort Buffington 2026-08-11 08:55:22 -05:00 committed by GitHub
parent 8bd467598c
commit 8a89804fda
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1 changed files with 6 additions and 14 deletions
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20
FM.cpp
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@ -27,14 +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;
// How long a link-mode external-audio underrun is tolerated before it is
// treated as a real end of transmission (see linkStateMachine()). A gap
// shorter than this is inaudible on its own; the PTT drop-and-rekey it
// would otherwise trigger is not. Tune here if needed -- no other code
// depends on this value.
const uint16_t FM_LINK_EXT_GAP_MS = 60U;
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;
@ -259,7 +253,6 @@ 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)
@ -267,8 +260,7 @@ void CFM::linkSamples(bool cos, q15_t* samples, uint8_t length)
// 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 -- silence, not stack garbage, must be
// what gets played out to the modem in that window.
// 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;
@ -1272,9 +1264,9 @@ void CFM::linkStateMachine(bool validRFSignal, bool validExtSignal)
// 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 inaudible on its own; the PTT
// drop-and-rekey it triggers is not. Give it a short grace period
// instead, mirroring the RELAYING_EXT/RELAYING_WAIT_EXT pattern the
// 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()) {