A method for determining orthopedic alignment is provided. The method includes monitoring a first and second sequence of signals transmitted from the first device to a second device, estimating a location of the first device from sensory measurements of the signals at respective sensors on the second device, calculating a set of phase differences, weighting a difference of an expected location and estimated location of the first device with the set of phase differences to produce a relative displacement, and reporting a position of an orthopedic instrument coupled to the first device based on the relative displacement.