diff --git a/vd960Loop/utilities/at32f421_freertos_demo/src/TaskLoop.c b/vd960Loop/utilities/at32f421_freertos_demo/src/TaskLoop.c
index cbd9198..3c89164 100644
--- a/vd960Loop/utilities/at32f421_freertos_demo/src/TaskLoop.c
+++ b/vd960Loop/utilities/at32f421_freertos_demo/src/TaskLoop.c
@@ -449,15 +449,15 @@ void vd1_task_per_channel(Loop154_Unit *unit)
      *    - 用途: 进入/离开检测判定
      *================================================================*/
 
-    /* 1a. 慢速 IIR — 斜率限幅 */
+    /* 1a. 慢速 IIR — 斜率限幅（参考 CAPVD）*/
     {
-        uint32_t fast_input;  // 快速 IIR 的输入：限幅后的原始值，不经慢速 IIR 滞后
+        uint32_t fast_input;
 
         if (unit->loop_CAPVD == 0) {
             unit->loop_CAPVD = unit->loop_Value;
             fast_input = unit->loop_Value;
         } else {
-            /* 斜率限幅: 物理车辆不可能让频率瞬间跳变 > MAX_SLOPE_RATE% */
+            /*--- 慢速路径：斜率限幅参考 CAPVD (τ=135ms)，保护基线跟踪 ---*/
             int32_t raw_delta = (int32_t)unit->loop_Value - (int32_t)unit->loop_CAPVD;
             int32_t max_step = (int32_t)(unit->loop_CAPVD * MAX_SLOPE_RATE / 100);
             if (max_step < 100) max_step = 100;
@@ -465,11 +465,21 @@ void vd1_task_per_channel(Loop154_Unit *unit)
             if (raw_delta < -max_step) raw_delta = -max_step;
             uint32_t clamped_value = (uint32_t)((int32_t)unit->loop_CAPVD + raw_delta);
             unit->loop_CAPVD = get_flt_value(clamped_value, unit->loop_CAPVD);
-            fast_input = clamped_value;
+
+            /*--- 快速路径：斜率限幅参考 CAPVD_fast (τ=28ms)，限幅窗口随快速值扩展 ---*/
+            if (unit->loop_CAPVD_fast == 0) {
+                fast_input = clamped_value;
+            } else {
+                int32_t f_delta = (int32_t)unit->loop_Value - (int32_t)unit->loop_CAPVD_fast;
+                int32_t f_max   = (int32_t)(unit->loop_CAPVD_fast * MAX_SLOPE_RATE / 100);
+                if (f_max < 100) f_max = 100;
+                if (f_delta > f_max)  f_delta = f_max;
+                if (f_delta < -f_max) f_delta = -f_max;
+                fast_input = (uint32_t)((int32_t)unit->loop_CAPVD_fast + f_delta);
+            }
         }
 
-        /* 1b. 快速 IIR — α=0.5: (old + new) / 2
-         * 输入直接用限幅后的原始值，不经过慢速 IIR，保持 τ≈28ms 的响应速度 */
+        /* 1b. 快速 IIR — α=0.5: (old + new) / 2 */
         if (unit->loop_CAPVD_fast == 0) {
             unit->loop_CAPVD_fast = fast_input;
         } else {