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[fix](trx-backend-soapysdr): retune wfm stereo difference path

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Co-authored-by: OpenAI Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>
This commit is contained in:
Stan Grams
2026-02-28 23:41:07 +01:00
parent 0dd91a952b
commit 9453c90dac
1 changed files with 2 additions and 2 deletions
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src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs
+2 -2
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@@ -18,7 +18,7 @@ const AUDIO_BW_HZ: f32 = 15_800.0;
/// Stereo L-R subchannel bandwidth for WFM (Hz). /// Stereo L-R subchannel bandwidth for WFM (Hz).
/// Keep this a bit lower than the mono path because the recovered difference /// Keep this a bit lower than the mono path because the recovered difference
/// signal is noisier and more prone to high-frequency artifacts. /// signal is noisier and more prone to high-frequency artifacts.
const STEREO_DIFF_BW_HZ: f32 = 13_500.0; const STEREO_DIFF_BW_HZ: f32 = 14_500.0;
/// Q values for a proper 4th-order Butterworth cascade (two 2nd-order stages). /// Q values for a proper 4th-order Butterworth cascade (two 2nd-order stages).
/// Stage 1: Q = 1 / (2 cos(π/8)) /// Stage 1: Q = 1 / (2 cos(π/8))
const BW4_Q1: f32 = 0.5412; const BW4_Q1: f32 = 0.5412;
@@ -29,7 +29,7 @@ const PILOT_NOTCH_Q: f32 = 5.0;
/// Narrow 19 kHz band-pass used to derive zero-crossings for switching stereo demod. /// Narrow 19 kHz band-pass used to derive zero-crossings for switching stereo demod.
const PILOT_BPF_Q: f32 = 20.0; const PILOT_BPF_Q: f32 = 20.0;
/// Fixed phase trim on the recovered L-R channel to compensate pilot-path delay. /// Fixed phase trim on the recovered L-R channel to compensate pilot-path delay.
const STEREO_SEPARATION_PHASE_TRIM: f32 = 0.012; const STEREO_SEPARATION_PHASE_TRIM: f32 = 0.015;
/// Fixed gain trim on the recovered L-R channel. /// Fixed gain trim on the recovered L-R channel.
const STEREO_SEPARATION_GAIN: f32 = 1.006; const STEREO_SEPARATION_GAIN: f32 = 1.006;
/// Extra headroom in the stereo matrix to reduce stereo-only clipping/IMD on /// Extra headroom in the stereo matrix to reduce stereo-only clipping/IMD on