sjg/trx-rs
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[fix](trx-backend-soapysdr): revert wfm resampler taps back to 16

Browse Source 
32 taps caused audio silence on real signals. Revert to 16 taps
which works correctly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>
This commit is contained in:
Stan Grams
2026-03-01 02:20:42 +01:00
parent edb456e843
commit a5e66ed287
1 changed files with 8 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs
+8 -3
View File
@@ -39,8 +39,7 @@ const STEREO_MATRIX_GAIN: f32 = 0.50;
/// and modulate higher-frequency stereo detail. /// and modulate higher-frequency stereo detail.
const STEREO_DIFF_DC_R: f32 = 0.9995; const STEREO_DIFF_DC_R: f32 = 0.9995;
/// Fractional-resampler FIR taps for WFM audio reconstruction. /// Fractional-resampler FIR taps for WFM audio reconstruction.
/// 32 taps gives ~50 dB stopband rejection, enough for clean treble. const WFM_RESAMP_TAPS: usize = 16;
const WFM_RESAMP_TAPS: usize = 32;
/// Polyphase slots for the WFM fractional FIR resampler. /// Polyphase slots for the WFM fractional FIR resampler.
const WFM_RESAMP_PHASES: usize = 32; const WFM_RESAMP_PHASES: usize = 32;
/// Slightly sub-Nyquist sinc cutoff to tame top-end imaging. /// Slightly sub-Nyquist sinc cutoff to tame top-end imaging.
@@ -235,7 +234,13 @@ unsafe fn fast_atan2_8_avx2(
let num = _mm256_blendv_ps(y, x, swap_mask); let num = _mm256_blendv_ps(y, x, swap_mask);
let den = _mm256_blendv_ps(x, y, swap_mask); let den = _mm256_blendv_ps(x, y, swap_mask);
let atan_input = _mm256_div_ps(num, den); // Add tiny epsilon to denominator to avoid 0/0 NaN when both x and y are zero.
let eps = _mm256_set1_ps(1.0e-30);
let safe_den = _mm256_or_ps(den, _mm256_and_ps(
_mm256_cmp_ps(den, _mm256_setzero_ps(), _CMP_EQ_OQ),
eps,
));
let atan_input = _mm256_div_ps(num, safe_den);
let mut result = atan_poly_avx2(atan_input); let mut result = atan_poly_avx2(atan_input);
// If swapped, result = copysign(π/2, atan_input) - result // If swapped, result = copysign(π/2, atan_input) - result