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[fix](trx-backend-soapysdr): reduce AM demod distortion

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Remove half-wave clipping from the AM coherent detector output and slow the carrier-reference tracking to reduce audible distortion.

Co-authored-by: Stan Grams <sjg@haxx.space>
Signed-off-by: Stan Grams <sjg@haxx.space>
This commit is contained in:
Stan Grams
2026-03-03 01:55:30 +01:00
parent 298b7247f8
commit e2e4d34f30
1 changed files with 2 additions and 2 deletions
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src/trx-server/trx-backend/trx-backend-soapysdr/src/demod/am.rs
+2 -2
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@@ -12,7 +12,7 @@ use num_complex::Complex;
/// the conjugate reference and take the in-phase projection. /// the conjugate reference and take the in-phase projection.
pub(super) fn demod_am(samples: &[Complex<f32>]) -> Vec<f32> { pub(super) fn demod_am(samples: &[Complex<f32>]) -> Vec<f32> {
const EPSILON: f32 = 1.0e-12; const EPSILON: f32 = 1.0e-12;
const REF_BLEND: f32 = 0.08; const REF_BLEND: f32 = 0.02;
let mut out = Vec::with_capacity(samples.len()); let mut out = Vec::with_capacity(samples.len());
let mut carrier_ref = Complex::new(1.0_f32, 0.0); let mut carrier_ref = Complex::new(1.0_f32, 0.0);
@@ -36,7 +36,7 @@ pub(super) fn demod_am(samples: &[Complex<f32>]) -> Vec<f32> {
// Project the original signal onto the limiter-derived carrier phase. // Project the original signal onto the limiter-derived carrier phase.
let mixed = sample * carrier_ref.conj(); let mixed = sample * carrier_ref.conj();
out.push(mixed.re.max(0.0)); out.push(mixed.re);
} }
out out