Comments on "Optimal minimal-order observer-estimators for discrete linear time-varying systems"

In Section IV of the above paper a method is developed for obtaining one explicit minimal-order optimal observer-estimator for the case in which some measurements are noisy while others are noise free. In this correspondence a more analytic and simpler method than the above one is presented. It is also shown that the simplest deadbeat observer given in Section V of the above paper can be refined.