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MMDVM
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76 Commits

Author SHA1 Message Date
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
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 5dd59fc473 Merge branch 'master' into mqtt 2025-08-28 17:00:21 +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 3e079f58ad Add RSSI reporting to FM and AX.25 2023-08-02 17:34:52 +01:00
Jonathan Naylor 7ef0d992d9 Improve the status reporting for FM mode. 2023-01-18 14:30:02 +00:00
Jonathan Naylor ee07f76bd5 Split the repeater and link mode audio paths. 2021-09-30 18:16:51 +01:00
Jonathan Naylor 6a4dad4c44 Change the LinkMode state machine. 2021-09-06 22:50:40 +01:00
Jonathan Naylor ed6bd66fab Rename SimpleMode to LinkMode. 2021-09-06 21:53:01 +01:00
Jonathan Naylor 70bf47f93e Add a bery simple FM mode for internet gatewaying. 2021-09-05 19:06:56 +01:00
Jonathan Naylor 81518bf74c Make AX.25, DMR, P25, NXDN and FM selectable at compile time. 2020-11-08 22:23:27 +00:00
Jonathan Naylor d8f138066e Add an experimental noise squelch. 2020-07-28 13:55:50 +01:00
Jonathan Naylor 9ff59570c7 Merge branch 'AX25' into AX25_FM 2020-07-15 10:42:43 +01:00
Jonathan Naylor dc41fd83d2 Test the use of a reverse burst at the end of a transmission. 2020-07-14 12:20:42 +01:00
Jonathan Naylor 20013e3adc Make Use COS As Lockout a run-time parameter and allow for different access modes. 2020-07-13 17:13:01 +01:00
Jonathan Naylor ad77fd60fd Remove KerchunkTX. 2020-07-07 17:57:31 +01:00
Jonathan Naylor aab8f5469f Add timeouts to the FM simplex state machine. 2020-07-06 10:56:35 +01:00
Jonathan Naylor c99f50575d Add a simpe simplex FM controller state machine. 2020-07-01 13:02:14 +01:00
Jonathan Naylor 14d5098018 Rename FMDownsampler to FMDownSampler. 2020-06-30 12:44:02 +01:00
Jonathan Naylor 0ea732780d Implement Kerchunk TX option. 2020-06-20 21:03:11 +01:00
Geoffrey Merck 994226e4b1 Tighten incoming data, Add FM UpSampler 2020-05-12 22:06:26 +02:00
Jonathan Naylor df0a9ebe72 Merge branch 'FM' into FM_Ext 2020-05-12 15:51:41 +01:00
Jonathan Naylor 435544f7a1 Add CTCSS hysteresis. 2020-05-12 13:55:30 +01:00
Geoffrey Merck b64712f657 Restore silence 2020-05-12 14:45:03 +02:00
Geoffrey Merck a0a3080da2 Make sure downsampler always buffers 22 samples at a time 2020-05-12 14:15:04 +02:00
Geoffrey Merck ca1cc7096a Fix modem not goign on transmit, still some cleansing to be done 2020-05-12 08:36:38 +02:00
Geoffrey Merck 042c26b3bb Trying to fix no tx, WIP 2020-05-11 22:32:24 +02:00
Jonathan Naylor 4a5a260c28 Perform FM mode changing in a more conventional manner. 2020-05-11 13:15:13 +01:00
Jonathan Naylor 67e0bf02e2 Merge branch 'FM' into FM_Ext 2020-05-09 13:06:32 +01:00
Jonathan Naylor 3bb7cde322 Add input audio delay to match the CTCSS decoder results. 2020-05-09 13:01:02 +01:00
Geoffrey Merck 05775f0bfa Add RingBuffer Template 2020-05-09 10:57:16 +02:00
Geoffrey Merck ff3e6feeb6 Use more explicit names 2020-05-09 08:00:24 +02:00
Geoffrey Merck 0e2a83bc7b Add incoming network data buffer 2020-05-09 07:57:45 +02:00
Geoffrey Merck e0234dfc00 Merge remote-tracking branch 'upstream/FM' into FM_Ext 2020-05-08 21:39:18 +02:00
Jonathan Naylor 9b0fed975c Buffer output after adding some initial silence. 2020-05-08 15:48:03 +01:00
Geoffrey Merck 9afcf3acc9 Merge remote-tracking branch 'upstream/FM' into FM_Ext 2020-05-08 12:00:36 +02:00
Geoffrey Merck feff1ee2c7 remove emphasis 2020-05-08 09:04:28 +02:00
Geoffrey Merck 77e0deee76 Make whole FM chain RX level independant 2020-05-08 09:01:00 +02:00
Jonathan Naylor d7cd7096d0 Add the external audio state machine and the beginnings of the audio 
processing.
 2020-05-07 22:39:17 +01:00
Jonathan Naylor 96364dc189 Add the external audio parameters. 2020-05-07 22:01:48 +01:00
Jonathan Naylor a816818e3f Beginnings of external audio for the FM controller. 2020-05-07 16:17:00 +01:00
Jonathan Naylor eb9c0dfd93 Allow for the inversion of COS levels. 2020-05-06 11:34:04 +01:00
Jonathan Naylor aa7a484c7a Allow the start callsign to occur when the kerchunk timer has latched. 2020-05-04 22:18:51 +01:00
Jonathan Naylor 4feca3c5b7 Clock the timers seperately. 2020-05-03 13:08:33 +01:00
Geoffrey Merck b23620ede3 Add de and pre emphasis 2020-04-29 20:42:20 +02:00
Geoffrey Merck cf18f95a92 Add Downsampling 2020-04-28 21:37:06 +02:00
Jonathan Naylor dac0f26e5d Rename RXBoost to RFAudioBoost. 2020-04-28 14:43:40 +01:00
Geoffrey Merck 93a8e63233 Remove m_rxLevel 2020-04-27 11:26:19 +02:00
Geoffrey Merck 4ffaa62855 Move division to CTCSSRX, change sample unscaling to 1/rxLevel 2020-04-27 11:16:06 +02:00