The present invention is directed to method and apparatus for determining a transducer's reference position in a disk drive having a disk surface with spiral servo information written thereon. The transducer comprises a read head for reading spiral servo information and a read signal envelope is generated when the read head reads the spiral servo information. An integration is performed over a first integration window, wherein the first integration window includes a read signal envelope. A reference position is determined for the read head using a second integration window (virtual integration window) that is included within, and smaller than, the first integration window. In one embodiment, the integration may be performed on a frame-by-frame basis. A determination may be made of the frame in the first integration window that includes a maximum sync amplitude. The second integration window may be centered using the frame that includes the maximum sync amplitude.