For non-minimum phase plants, a partial LTR design of optimal output disturbance cancellation controllers is discussed. A target recoverable by the partial LTR procedure is identified as an output injection with a frequency-shaped gain matrix. The partial LTR result is used to clarify system-theoretic meaning of enforcing the minimum phase LTR procedure. It is shown that the partial LTR procedu...

An important statement in Quantitative Feedback Theory(QFT) is that the nominal plant can be chosen arbitrarily whether or not it is a member of the plant set. Based on this statement, a design method for non-minimum phase and unstable plants proposed by Horowitz is to choose the stable minimum phase plant as the nominal plant. This report shows this statement is incorrect by several counterexa...

Recursive inverse filtering with non-stationary filters is becoming a useful tool in a range of applications, from multi-dimensional inverse problems to wave extrapolation. I formulate causal non-stationary convolution and combination and their adjoints in such a way that it is apparent that the corresponding non-stationary recursive filters are true inverse processes. Stationary recursive inve...

In the field of linear time-invariant systems, a process is identified as a nonminimum phase (NMP) system if its transfer function has at least one right half-plane (RHP) zero, or a RHP pole, or a time delay. Among others, systems with RHP zero(s) constitute a very important category of NMP systems, both from theoretical and practical point of view. Such zeros appear in many realworld systems s...

Surface-consistent deconvolution is a standard processing technique in land data to uniformize the wavelet across all sources and receivers. The required wavelet estimation step is generally done in the homomorphic domain since this is a convenient way to separate the phase and the amplitude spectrum in a linear fashion. Unfortunately all surface-consistent deconvolutions make a minimum-phase a...