diff --git a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/bd/FocusCalculator3.java b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/bd/FocusCalculator3.java
index f300c85a..a208dbc6 100644
--- a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/bd/FocusCalculator3.java
+++ b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/bd/FocusCalculator3.java
@@ -14,6 +14,7 @@ public class FocusCalculator3 extends FocusCalculator1{
     public FocusCalculator3(Device bsDevice){
         super();
         this.bsDevice = bsDevice;
+        gravityMinCount = 80;
     }
 /*
     static class EComparator implements Comparator<double[]>{