diff --git a/AsbCloudInfrastructure/Services/DetectOperations/OperationDetectionBackgroundService.cs b/AsbCloudInfrastructure/Services/DetectOperations/OperationDetectionBackgroundService.cs
index ead356ca..e4a6867b 100644
--- a/AsbCloudInfrastructure/Services/DetectOperations/OperationDetectionBackgroundService.cs
+++ b/AsbCloudInfrastructure/Services/DetectOperations/OperationDetectionBackgroundService.cs
@@ -173,7 +173,14 @@ namespace AsbCloudInfrastructure.Services.DetectOperations
 
                 if (!isDetected)
                 {
-                    startDate = startDate.AddSeconds(0.95 * take);
+                    var i = skip - minFragmentLength;
+                    i = i > data.Length
+                        ? data.Length - minStepLength
+                        : i;
+                    i = i < minFragmentLength
+                        ? minFragmentLength
+                        : i;
+                    startDate = data[i].DateTime;
                 }
             }