### Optimization and Systems Theory Seminar

Tuesday, September 16, 2003, 11.00-12.00, Room 3721, Lindstedtsv. 25

**Professor Yutaka Yamamoto**

Department of Applied Analysis and Complex Dynamical Systems

Graduate School of Informatics

Kyoto University

Kyoto 606-8501

Japan

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Signal processing via sampled-data control theory

There has been remarkable progress in sampled-data control theory in
the last decade. The main accomplishment here is that there exists a
digital (discrete-time) control law that takes the intersampling
behavior into account and makes the overall analog (continuous-time)
performance optimal, in the sense of H-infinity norm. It has been
also recognized that the new method can give rise to a substantial
improvement in analog performance. The crux of this theory is in
incorporating an analog model for the design of digital controllers.
Digital signal processing also aims at designing a digital controller (filter)
for an optimal processing of analog signals. While this has much in common
with sampled-data control theory, the primary analog model employed thus far
is based on Shannon perfect band-limited assmption.

We observe that this can often lead to a fairly undesirable result,
e.g., harsh ringing in CD processing, block and mosquito noise in
digital images, and show that sampled-data theory can provide an
optimal platform to circumvent such defects. We will give a new
design method based on H-infinity sampled-data control theory not
based on the perfect band-limited hypothesis. Examples of sound/image
processing will be presented to illustrate the advantage of the
proposed theory.

Calendar of seminars

*Last update: September 1, 2003 by
Anders Forsgren,
anders.forsgren@math.kth.se.
*