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[fix](trx-backend-soapysdr): retune wfm sum and diff cutoffs

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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 23:55:17 +01:00
parent 635d2b39bb
commit 32822effda
1 changed files with 4 additions and 5 deletions
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src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs
+4 -5
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@@ -11,14 +11,13 @@ const RDS_BPF_Q: f32 = 10.0;
/// Pilot tone frequency (Hz).
const PILOT_HZ: f32 = 19_000.0;
/// Audio bandwidth for WFM (Hz).
/// 15.8 kHz leaves more guard band below the 19 kHz pilot and reduces
/// top-end artifacts on strong signals while still preserving the useful
/// broadcast audio range.
const AUDIO_BW_HZ: f32 = 15_800.0;
/// 17 kHz preserves more top-end while still leaving guard band below the
/// 19 kHz pilot.
const AUDIO_BW_HZ: f32 = 17_000.0;
/// Stereo L-R subchannel bandwidth for WFM (Hz).
/// Keep this a bit lower than the mono path because the recovered difference
/// signal is noisier and more prone to high-frequency artifacts.
const STEREO_DIFF_BW_HZ: f32 = 14_500.0;
const STEREO_DIFF_BW_HZ: f32 = 15_800.0;
/// Q values for a proper 4th-order Butterworth cascade (two 2nd-order stages).
/// Stage 1: Q = 1 / (2 cos(π/8))
const BW4_Q1: f32 = 0.5412;