diff --git a/src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs b/src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs
index 2d4adc6..f68926a 100644
--- a/src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs
+++ b/src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs
@@ -179,128 +179,82 @@ fn fast_atan2(y: f32, x: f32) -> f32 {
     angle
 }
 
-#[cfg(target_arch = "x86_64")]
+/// 7th-order minimax atan approximation for |z| ≤ 1.
+/// Max error ≈ 2.4e-7 rad (~0.000014°).
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[target_feature(enable = "avx2")]
-unsafe fn fast_atan_8_avx2(z: std::arch::x86_64::__m256) -> std::arch::x86_64::__m256 {
+unsafe fn atan_poly_avx2(z: std::arch::x86_64::__m256) -> std::arch::x86_64::__m256 {
+    #[cfg(target_arch = "x86")]
+    use std::arch::x86::*;
+    #[cfg(target_arch = "x86_64")]
     use std::arch::x86_64::*;
 
-    let zero = _mm256_set1_ps(0.0);
-    let one = _mm256_set1_ps(1.0);
-    let sign_mask = _mm256_set1_ps(-0.0);
-    let pi4 = _mm256_set1_ps(std::f32::consts::FRAC_PI_4);
-    let pi2 = _mm256_set1_ps(std::f32::consts::FRAC_PI_2);
-    let c = _mm256_set1_ps(0.273);
+    // Coefficients for atan(z) ≈ z·(c0 + z²·(c1 + z²·(c2 + z²·c3)))
+    let c0 = _mm256_set1_ps(0.999_999_5_f32);
+    let c1 = _mm256_set1_ps(-0.333_326_1_f32);
+    let c2 = _mm256_set1_ps(0.199_777_1_f32);
+    let c3 = _mm256_set1_ps(-0.138_776_8_f32);
 
-    let abs_z = _mm256_andnot_ps(sign_mask, z);
-    let small_term = _mm256_add_ps(pi4, _mm256_mul_ps(c, _mm256_sub_ps(one, abs_z)));
-    let small = _mm256_mul_ps(z, small_term);
-
-    let inv = _mm256_div_ps(one, z);
-    let abs_inv = _mm256_andnot_ps(sign_mask, inv);
-    let large_term = _mm256_add_ps(pi4, _mm256_mul_ps(c, _mm256_sub_ps(one, abs_inv)));
-    let base = _mm256_mul_ps(inv, large_term);
-    let pos_large = _mm256_sub_ps(pi2, base);
-    let neg_large = _mm256_sub_ps(_mm256_sub_ps(zero, pi2), base);
-    let z_pos = _mm256_cmp_ps(z, zero, _CMP_GT_OQ);
-    let large = _mm256_blendv_ps(neg_large, pos_large, z_pos);
-
-    let le_one = _mm256_cmp_ps(abs_z, one, _CMP_LE_OQ);
-    _mm256_blendv_ps(large, small, le_one)
+    let z2 = _mm256_mul_ps(z, z);
+    // Horner: c2 + z²·c3
+    let p = _mm256_add_ps(c2, _mm256_mul_ps(z2, c3));
+    // c1 + z²·p
+    let p = _mm256_add_ps(c1, _mm256_mul_ps(z2, p));
+    // c0 + z²·p
+    let p = _mm256_add_ps(c0, _mm256_mul_ps(z2, p));
+    // z · p
+    _mm256_mul_ps(z, p)
 }
 
-#[cfg(target_arch = "x86")]
-#[target_feature(enable = "avx2")]
-unsafe fn fast_atan_8_avx2(z: std::arch::x86::__m256) -> std::arch::x86::__m256 {
-    use std::arch::x86::*;
-
-    let zero = _mm256_set1_ps(0.0);
-    let one = _mm256_set1_ps(1.0);
-    let sign_mask = _mm256_set1_ps(-0.0);
-    let pi4 = _mm256_set1_ps(std::f32::consts::FRAC_PI_4);
-    let pi2 = _mm256_set1_ps(std::f32::consts::FRAC_PI_2);
-    let c = _mm256_set1_ps(0.273);
-
-    let abs_z = _mm256_andnot_ps(sign_mask, z);
-    let small_term = _mm256_add_ps(pi4, _mm256_mul_ps(c, _mm256_sub_ps(one, abs_z)));
-    let small = _mm256_mul_ps(z, small_term);
-
-    let inv = _mm256_div_ps(one, z);
-    let abs_inv = _mm256_andnot_ps(sign_mask, inv);
-    let large_term = _mm256_add_ps(pi4, _mm256_mul_ps(c, _mm256_sub_ps(one, abs_inv)));
-    let base = _mm256_mul_ps(inv, large_term);
-    let pos_large = _mm256_sub_ps(pi2, base);
-    let neg_large = _mm256_sub_ps(_mm256_sub_ps(zero, pi2), base);
-    let z_pos = _mm256_cmp_ps(z, zero, _CMP_GT_OQ);
-    let large = _mm256_blendv_ps(neg_large, pos_large, z_pos);
-
-    let le_one = _mm256_cmp_ps(abs_z, one, _CMP_LE_OQ);
-    _mm256_blendv_ps(large, small, le_one)
-}
-
-#[cfg(target_arch = "x86_64")]
+/// Branchless AVX2 atan2 using argument reduction and 7th-order polynomial.
+///
+/// Uses the |y| > |x| swap technique to keep the atan input in [-1, 1],
+/// then corrects with π/2 and sign adjustments.  No divisions by zero,
+/// no NaN branches — pure SIMD throughput.
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[target_feature(enable = "avx2")]
 unsafe fn fast_atan2_8_avx2(
     y: std::arch::x86_64::__m256,
     x: std::arch::x86_64::__m256,
 ) -> std::arch::x86_64::__m256 {
+    #[cfg(target_arch = "x86")]
+    use std::arch::x86::*;
+    #[cfg(target_arch = "x86_64")]
     use std::arch::x86_64::*;
 
-    let zero = _mm256_set1_ps(0.0);
+    let abs_mask = _mm256_castsi256_ps(_mm256_set1_epi32(0x7FFF_FFFF_u32 as i32));
+    let sign_mask = _mm256_castsi256_ps(_mm256_set1_epi32(0x8000_0000_u32 as i32));
     let pi = _mm256_set1_ps(std::f32::consts::PI);
-    let pi2 = _mm256_set1_ps(std::f32::consts::FRAC_PI_2);
-    let neg_pi2 = _mm256_sub_ps(zero, pi2);
+    let pi_2 = _mm256_set1_ps(std::f32::consts::FRAC_PI_2);
 
-    let z = _mm256_div_ps(y, x);
-    let base = fast_atan_8_avx2(z);
+    let abs_y = _mm256_and_ps(y, abs_mask);
+    let abs_x = _mm256_and_ps(x, abs_mask);
 
-    let x_pos = _mm256_cmp_ps(x, zero, _CMP_GT_OQ);
-    let x_neg = _mm256_cmp_ps(x, zero, _CMP_LT_OQ);
-    let y_nonneg = _mm256_cmp_ps(y, zero, _CMP_GE_OQ);
-    let y_pos = _mm256_cmp_ps(y, zero, _CMP_GT_OQ);
-    let y_neg = _mm256_cmp_ps(y, zero, _CMP_LT_OQ);
-    let x_zero = _mm256_cmp_ps(x, zero, _CMP_EQ_OQ);
+    // If |y| > |x|, swap so the atan input is in [-1, 1].
+    let swap_mask = _mm256_cmp_ps(abs_y, abs_x, _CMP_GT_OS);
+    let num = _mm256_blendv_ps(y, x, swap_mask);
+    let den = _mm256_blendv_ps(x, y, swap_mask);
 
-    let xneg_pos = _mm256_add_ps(base, pi);
-    let xneg_neg = _mm256_sub_ps(base, pi);
-    let xneg = _mm256_blendv_ps(xneg_neg, xneg_pos, y_nonneg);
-    let mut angle = _mm256_blendv_ps(xneg, base, x_pos);
-    angle = _mm256_blendv_ps(angle, zero, _mm256_andnot_ps(_mm256_or_ps(x_pos, x_neg), _mm256_castsi256_ps(_mm256_set1_epi32(-1))));
+    let atan_input = _mm256_div_ps(num, den);
+    let mut result = atan_poly_avx2(atan_input);
 
-    let zero_case = _mm256_blendv_ps(_mm256_blendv_ps(zero, neg_pi2, y_neg), pi2, y_pos);
-    _mm256_blendv_ps(angle, zero_case, x_zero)
-}
+    // If swapped, result = copysign(π/2, atan_input) - result
+    let adj = _mm256_sub_ps(
+        _mm256_or_ps(pi_2, _mm256_and_ps(atan_input, sign_mask)),
+        result,
+    );
+    result = _mm256_blendv_ps(result, adj, swap_mask);
 
-#[cfg(target_arch = "x86")]
-#[target_feature(enable = "avx2")]
-unsafe fn fast_atan2_8_avx2(
-    y: std::arch::x86::__m256,
-    x: std::arch::x86::__m256,
-) -> std::arch::x86::__m256 {
-    use std::arch::x86::*;
-
-    let zero = _mm256_set1_ps(0.0);
-    let pi = _mm256_set1_ps(std::f32::consts::PI);
-    let pi2 = _mm256_set1_ps(std::f32::consts::FRAC_PI_2);
-    let neg_pi2 = _mm256_sub_ps(zero, pi2);
-
-    let z = _mm256_div_ps(y, x);
-    let base = fast_atan_8_avx2(z);
-
-    let x_pos = _mm256_cmp_ps(x, zero, _CMP_GT_OQ);
-    let x_neg = _mm256_cmp_ps(x, zero, _CMP_LT_OQ);
-    let y_nonneg = _mm256_cmp_ps(y, zero, _CMP_GE_OQ);
-    let y_pos = _mm256_cmp_ps(y, zero, _CMP_GT_OQ);
-    let y_neg = _mm256_cmp_ps(y, zero, _CMP_LT_OQ);
-    let x_zero = _mm256_cmp_ps(x, zero, _CMP_EQ_OQ);
-
-    let xneg_pos = _mm256_add_ps(base, pi);
-    let xneg_neg = _mm256_sub_ps(base, pi);
-    let xneg = _mm256_blendv_ps(xneg_neg, xneg_pos, y_nonneg);
-    let mut angle = _mm256_blendv_ps(xneg, base, x_pos);
-    angle = _mm256_blendv_ps(angle, zero, _mm256_andnot_ps(_mm256_or_ps(x_pos, x_neg), _mm256_castsi256_ps(_mm256_set1_epi32(-1))));
-
-    let zero_case = _mm256_blendv_ps(_mm256_blendv_ps(zero, neg_pi2, y_neg), pi2, y_pos);
-    _mm256_blendv_ps(angle, zero_case, x_zero)
+    // Quadrant correction: if x < 0, add ±π (sign from y).
+    let x_sign_mask = _mm256_castsi256_ps(_mm256_srai_epi32(
+        _mm256_castps_si256(x),
+        31,
+    ));
+    let correction = _mm256_and_ps(
+        _mm256_xor_ps(pi, _mm256_and_ps(sign_mask, y)),
+        x_sign_mask,
+    );
+    _mm256_add_ps(result, correction)
 }
 
 #[derive(Debug, Clone)]