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Opt-in channel-power squelch for AM audio RX (#3315)

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* AM: add opt-in channel-power squelch for AM audio RX

Add an SDR++-style power squelch on the complex channel signal for the
Analog Audio RX app in AM modes (DSB/SSB/CW). The squelch measures the
mean channel power, converts it to dBFS, and mutes the demodulated audio
when the signal is below a user-set threshold. Being carrier-based it
keys on the AM carrier (e.g. airband/ATC) rather than on audio-band
noise, which the existing FM squelch could not do for AM.

A new 'SQ' field (0-99, 0 = off) is added to the AM options view and is
persisted per app via app_settings. Default is 0, so existing AM
behaviour is unchanged unless the user enables it. Threshold maps 1..99
to -80..-20 dBFS.

Touches: message (AMConfigureMessage.squelch_level), baseband_api
(AMConfig::apply), receiver_model (am_squelch_level get/set),
app_settings (persistence), proc_am_audio (DSP), analog_audio_app (UI).

* Refactor audio power calculation to use magnitude squared

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
This commit is contained in:
Mo
2026-09-14 20:54:54 +02:00
committed by GitHub
parent d72b5ed0b1
commit b8ad44c431
11 changed files with 78 additions and 10 deletions
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firmware/application/baseband_api.cpp
+5 -4
View File
@@ -70,11 +70,11 @@ static void send_message(const Message* const message) {
}
}
void AMConfig::apply() const {
apply((AMConfigureMessage::Zoom_waterfall)spectrum_decimation_factor);
void AMConfig::apply(const uint8_t squelch_level) const {
apply((AMConfigureMessage::Zoom_waterfall)spectrum_decimation_factor, squelch_level);
}
void AMConfig::apply(const AMConfigureMessage::Zoom_waterfall spectrum_zoom) const {
void AMConfig::apply(const AMConfigureMessage::Zoom_waterfall spectrum_zoom, const uint8_t squelch_level) const {
const AMConfigureMessage message{
taps_6k0_decim_0, // common FIR filter taps pre-decim_0 to all 6 x AM mod types.(AM-9K, AM-6K, USB, LSB, CW, AMFM-WFAX)
decim_1, // var decim_1 FIR taps filter , variable values , to handle two spectrum decim factor 1 and 2 (zoom) and more APT LPF filtered .
@@ -82,7 +82,8 @@ void AMConfig::apply(const AMConfigureMessage::Zoom_waterfall spectrum_zoom) con
channel, // var channel FIR taps filter , variable values, depending selected AM mode, each one different (DSB-9K, DSB-6K, USB-3K, LSB-3K,CW,AMFM-WFAX)
modulation, // var parameter . enum class Modulation : int32_t {DSB = 0, SSB = 1, SSB_FM = 2}
audio_12k_iir_filter_config, // var parameter , 300 Hz hpf all except Wefax (1.500Hz lpf)
(size_t)spectrum_zoom};
(size_t)spectrum_zoom,
squelch_level};
send_message(&message);
audio::set_rate(audio::Rate::Hz_12000);
}