The present invention provides a system and method for automatically controlling the phase of the clock signal for sampling an HDTV signal, which implements a new and improved method for phase detection. The system and method utilize the standard format of an HDTV signal to consistently ensure accurate phase detection. Particularly, the system and method detect the target phase for the sampling clock using a tri-level sync pattern that exists at the beginning of each display line. This tri-level sync pattern or “sync pulse” is well suited for phase detection since it includes several static areas separated by substantial transitions. Furthermore, by using the sync pulse of the HDTV signal, the system and method provide consistent and accurate results, since the sync pulse will not change regardless of the whether the video data is static or in motion.