Disclosed is a method and apparatus for calibrating a time vernier in an automatic test equipment (ATE) system, the method including generating a data signal and a reference signal whose periods differ by a small amount (dt), using precession of the data signal and reference signal to create accurate delay increments, and creating a trigger signal for Bit Error Rate Test (BERT) counting, the trigger signal having a select frequency such than an integer number (N) of triggers are generated with a precession period (TPREC). Upon occurrence of each trigger, a BERT is initiated for measuring data to determine strobe positions with respect to the data signal.