In this paper, we show that signal sampling operation can be considered as a kind of all-pass filtering in the time domain, when Nyquist frequency is larger or equal to maximal spectrum sampled. We demonstrate seemingly obvious observation has wide-ranging implications. They are discussed here detail. Furthermore, discuss also shaping effects occur case under-sampling. That is, smaller than Fur...

We consider optical systems composed of an arbitrary number of lenses and filters, separated by arbitrary distances, under the standard approximations of Fourier optics. We show that every such system is equivalent to (i) consecutive filtering operations in several fractional Fourier domains and (ii) consecutive filtering operations alternately in the space and the frequency domains.

The effect of filtering the time trajectories of spectral envelopes on speech intelligibility was investigated. Since LPC cepstrum forms the basis of many automatic speech recognition systems, we filtered time trajectories of LPC cepstrum of speech sounds, and the modified speech was reconstructed after the filtering. For processing, we applied low-pass, high-pass and band-pass filters. The res...

There is a need for automatic methods for parametrization of the voice source signals. Representatives of the two types of methods that have been used most often for parametrization were tested and compared. For this purpose a novel evaluation procedure is proposed which makes it possible to perform the numerous tests needed for a detailed comparison of the methods. This evaluation procedure re...

In iterative learning control (ILC), it is highly desirable to have a learning compensator with a unitgain for all frequencies, in order to avoid noise amplification and learning speed degradation during the learning process. In this paper, we show that the realization of a unit-gain compensator is straightforward in ILC, using both forward and backward filtering. As an illustrative example, a ...

1 Basics of Noise Reduction ......................................2 2 Noise Reduction on the SC140 Core ......................5 2.1 Fast Fourier Transform ...........................................5 2.2 Logarithmic Function ..............................................7 2.3 Exponential Function ..............................................7 2.4 Low-Pass Filter ..................................

Introduction: In principle, gadolinium-enhanced carotid MRA has well-documented advantages over methods based on time-offlight contrast. Unfortunately, conventional Fourier imaging methods fail to achieve adequate spatial resolution because data acquisition is limited to the brief first pass of contrast material. However, the conventional Fourier sampling theorem does not exploit the strong pri...