{HEAD ~ The method} 2, wherein {TAIL ~ the magnitude} and phase angle of both the pseudo tracking servo output signal and the tracking servo output signal are identical 
{ HEAD ~ The method } 2 , wherein { TAIL ~ the magnitude } and phase angle of both the pseudo tracking servo output signal and the tracking servo output signal are identical
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH