Topic
Linear phase
About: Linear phase is a research topic. Over the lifetime, 5504 publications have been published within this topic receiving 79723 citations.
Papers published on a yearly basis
Papers
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TL;DR: A simple and efficient linear phase lead compensation repetitive control scheme for engineers to develop high-performance power converter systems that helps a repetitive controller to achieve faster convergence rate, higher tracking accuracy, and wider stability region.
Abstract: This paper presents a simple and efficient linear phase lead compensation repetitive control scheme for engineers to develop high-performance power converter systems. The linear phase lead compensation helps a repetitive controller to achieve faster convergence rate, higher tracking accuracy, and wider stability region. In the proposed scheme, the phase lead compensation repetitive controller is plugged into generic state-feedback-controlled converter systems. Its comprehensive synthesis, which involves principle, analysis, design, modeling, implementation, and experiments, is systematically and completely presented in great detail. A complete series of experiments is successfully carried out to verify the solution.
239 citations
TL;DR: A class of lapped orthogonal transforms with extended overlap (GenLOTs) is developed as a subclass of the general class of LPPUFB as a method to process finite-length signals.
Abstract: The general factorization of a linear-phase paraunitary filter bank (LPPUFB) is revisited. From this new perspective, a class of lapped orthogonal transforms with extended overlap (generalized linear-phase lapped orthogonal transforms (GenLOTs)) is developed as a subclass of the general class of LPPUFB. In this formulation, the discrete cosine transform (DCT) is the order-1 GenLOT, the lapped orthogonal transform is the order-2 GenLOT, and so on, for any filter length that is an integer multiple of the block size. The GenLOTs are based on the DCT and have fast implementation algorithms. The implementation of GenLOTs is explained, including the method to process finite-length signals. The degrees of freedom in the design of GenLOTs are described, and design examples are presented along with image compression tests.
235 citations
TL;DR: A direct measurement of the amplitude and the phase of a femtosecond light pulse is performed for the first time to the authors' knowledge, and the time dependence of the field can be easily obtained by a Fourier transform.
Abstract: A direct measurement of the amplitude and the phase of a femtosecond light pulse is performed for the first time to our knowledge The measurement is made in the frequency domain, and the time dependence of the field can be easily obtained by a Fourier transform The technique relies on a pulse synthesis scheme to unravel the frequency dependence of the phase A mask filters the spectrum, which gives rise to a pulse with a measurable temporal profile related to the frequency dependence of the phase In particular, with a rectangular slit the time delay of the synthesized pulse is the first derivative of the phase with respect to the frequency of the original pulse at the central frequency of the filter The amplitude of the spectrum is obtained from the power spectrum
233 citations
TL;DR: The phase response and resulting dispersion of optical filters in general and their impact on WDM system performance are considered and possible ways of linearizing the phase response without affecting the amplitude response are considered in an attempt to approximate the ideal filter and achieve the highest bandwidth utilization.
Abstract: Wavelength division multiplexing (WDM) communication systems invariably require good optical filters meeting stringent requirements on their amplitude response, the ideal being a perfectly rectangular filter. To achieve high bandwidth utilization, the phase response of these filters is of equal importance, with the ideal filter having perfectly linear phase and therefore constant time delay and no dispersion. This aspect of optical filters for WDM systems has not received much attention until very recently. It is the objective of this paper to consider the phase response and resulting dispersion of optical filters in general and their impact on WDM system performance. To this end we use general concepts from linear systems, in particular, minimum and nonminimum phase response and the applicability of Hilbert transforms (also known as Kramers-Kronig relations). We analyze three different classes of optical filters, which are currently being used in WDM systems and compare their performance in terms of their phase response. Finally, we consider possible ways of linearizing the phase response without affecting the amplitude response, in an attempt to approximate the ideal filter and achieve the highest bandwidth utilization.
215 citations
TL;DR: In this paper, the authors developed a simple, high-speed, nearly vibration-free, mechanically scanned, optical delay line suitable for femtosecond time-resolved signal-averaging measurements.
Abstract: We have developed a simple, high-speed, nearly vibration-free, mechanically scanned, optical delay line suitable for femtosecond time-resolved signal-averaging measurements. We demonstrate a 2-ps time window autocorrelator with a display updated at 400 Hz. The delay line uses a dithering planar mirror as a time-varying linear phase ramp in the spectral plane of a modified grating-lens femtosecond pulse shaper. The time delay is linearly proportional to the angular deviation of the mirror. The high speed and low vibration are a result of the extremely small angular changes required to generate a large time delay.
205 citations