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[fix](trx-cw): widen tone scan range and clamp by Nyquist

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Expand CW decoder tone scan/control range to 100-10000 Hz and cap the
upper bound by sample-rate Nyquist to keep detection stable.

Co-authored-by: Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>
This commit is contained in:
Stan Grams
2026-03-04 23:05:10 +01:00
parent f3f0b1dfd3
commit c1f37a320f
1 changed files with 17 additions and 4 deletions
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src/decoders/trx-cw/src/lib.rs
+17 -4
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@@ -89,12 +89,21 @@ fn goertzel_energy(buf: &[f32], coeff: f32) -> f32 {
// Tone scan bins // Tone scan bins
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
const TONE_SCAN_LOW: u32 = 300; const TONE_SCAN_LOW: u32 = 100;
const TONE_SCAN_HIGH: u32 = 1200; const TONE_SCAN_HIGH: u32 = 10_000;
const TONE_SCAN_STEP: u32 = 25; const TONE_SCAN_STEP: u32 = 25;
const TONE_STABLE_NEEDED: u32 = 3; const TONE_STABLE_NEEDED: u32 = 3;
const THRESHOLD: f32 = 0.05; const THRESHOLD: f32 = 0.05;
fn tone_scan_high_for_sample_rate(sample_rate: u32) -> u32 {
let nyquist = sample_rate / 2;
if nyquist <= TONE_SCAN_LOW + 1 {
TONE_SCAN_LOW
} else {
TONE_SCAN_HIGH.min(nyquist - 1)
}
}
struct ToneScanBin { struct ToneScanBin {
freq: u32, freq: u32,
coeff: f32, coeff: f32,
@@ -152,7 +161,8 @@ impl CwDecoder {
// Build scan bins // Build scan bins
let mut tone_scan_bins = Vec::new(); let mut tone_scan_bins = Vec::new();
let mut f = TONE_SCAN_LOW; let mut f = TONE_SCAN_LOW;
while f <= TONE_SCAN_HIGH { let scan_high = tone_scan_high_for_sample_rate(sample_rate);
while f <= scan_high {
let bk = (f as f32 * window_size as f32 / sample_rate as f32).round(); let bk = (f as f32 * window_size as f32 / sample_rate as f32).round();
let b_omega = (2.0 * std::f32::consts::PI * bk) / window_size as f32; let b_omega = (2.0 * std::f32::consts::PI * bk) / window_size as f32;
tone_scan_bins.push(ToneScanBin { tone_scan_bins.push(ToneScanBin {
@@ -195,7 +205,10 @@ impl CwDecoder {
} }
pub fn set_tone_hz(&mut self, tone_hz: u32) { pub fn set_tone_hz(&mut self, tone_hz: u32) {
let tone_hz = tone_hz.clamp(TONE_SCAN_LOW, TONE_SCAN_HIGH); let tone_hz = tone_hz.clamp(
TONE_SCAN_LOW,
tone_scan_high_for_sample_rate(self.sample_rate),
);
self.recompute_goertzel(tone_hz); self.recompute_goertzel(tone_hz);
} }