We investigated applying the stability of the position on the optical axis direction corresponding to the phase minimum values of different frequencies for signal processing in multiple pulse-train interferometry. We calculated the position on the optical axis direction corresponding to the phase minimum value of different frequencies and obtained accurate peak position measurements of the fringe envelope using our selected frequency components. We chose this method because matching phases of frequencies means that these frequencies are less affected by measurement noise. We used an unbalanced Michelson interferometer with a fixed mirror position measurement to evaluate the performance of our proposed system. This method is expected to be useful for simple and long-range absolute distance measurements.