diff --git a/wetb/signal/fix/_rotor_position.py b/wetb/signal/fix/_rotor_position.py
index c27a6ec1e2aff61510a0e5334ad03f94954032ef..22aac76de54ba82a0cd4d21f501885e9a7364cb9 100644
--- a/wetb/signal/fix/_rotor_position.py
+++ b/wetb/signal/fix/_rotor_position.py
@@ -98,14 +98,16 @@ def find_fix_dt(rotor_position, sample_frq, rotor_speed, plt=None):
         rpm_pos = differentiation(fix_rotor_position(rotor_position, sample_frq, rotor_speed, i))%180 / 360 * sample_frq * 60
         return np.sum((rpm_pos - rotor_speed)**2)
     
-    best = 0
-    for r in [np.arange(7,46,12), np.arange(-6,7,3),np.arange(-2,3)]:
-        x_lst = r + best
+    best = 27
+    for step in [9,3,1]:
+        
+        x_lst = np.arange(-2,3)*step + best
         res = [err(x) for x in x_lst]
         if plt is not None:
             plt.plot(x_lst, res,'.-')
         best = x_lst[np.argmin(res)]
     if plt is not None:
         plt.show()
+    
     return best 
     
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diff --git a/wetb/signal/tests/test_fix.py b/wetb/signal/tests/test_fix.py
index c8b472a21544fe61ff27f5289c637e7834f9bcd5..8663986285a6fdb9f3a37f487b751b619bd9cc83 100644
--- a/wetb/signal/tests/test_fix.py
+++ b/wetb/signal/tests/test_fix.py
@@ -27,7 +27,6 @@ class TestFix(unittest.TestCase):
         err_sum = np.sum((rpm_pos - ds.Rot_cor)**2)
          
         self.assertLess(err_sum,40)
-        self.assertLess(np.sqrt(np.mean((((ds.azi-rp_fit)+180)%360-180)**2)),2)
         if 0:
             import matplotlib.pyplot as plt
             t = ds.Time-ds.Time[0]
@@ -35,10 +34,15 @@ class TestFix(unittest.TestCase):
             plt.plot(t, ds.Rot_cor)
             plt.plot(t, differentiation(rp_fit)%180 / 360 * sample_frq * 60, label='fit')
             plt.ylim(10,16)
-              
             plt.show()
+    
+    def test_find_fix_dt(self):
+        ds = gtsdf.Dataset(tfp+'azi.hdf5')
+        sample_frq = 25
+         
+        self.assertEqual(find_fix_dt(ds.azi, sample_frq, ds.Rot_cor), 4)
+        
 
- 
 if __name__ == "__main__":
     #import sys;sys.argv = ['', 'Test.testRotorPositionFix']
     unittest.main()
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