An ink-jet head mount to guide positions of ink-jet heads with a high precision and an ink-jet printing apparatus including the same. Such an approach includes a strong identification mechanism to get a positive identification on a person and a weak identification mechanism to maintain location information for the person moving in a facility. Each periphery flange defines a recess to receive the corresponding electric circuit board. In operation, the delay receives the input signal and generates a delayed input signal and the difference integrator receives the delayed and input signals and generates a frequency estimate value representing both the estimated central frequency of the input signal and the estimated energy of the input signal.