 When both signals are nearly equal in strength, or are fading independently, the receiver may  switch from one to the other and exhibit picket fencing.
<clarity>  When both signals are nearly equal in strength, or are fading independently, the receiver may  switch from one to the other and exhibit picket fencing.
 When both signals are nearly equal in strength, or are fading independently, the receiver may rapidly switch from one to the other and exhibit picket fencing.