نتایج جستجو برای: time fourier transform

تعداد نتایج: 1995949  

Journal: :Applied optics 1980
D Casasent D Psaltis

A review of multichannel long integration time, optical Fourier transform techniques for advanced Fourier spectroscopy systems is followed by the description of a new multichannel time-integrating optical Fourier transform chirp-Z system and a discussion of its use in Fourier spectroscopy signal processing.

Journal: :Electronics Letters 2023

This letter addresses the coherent integration problem for detecting high-speed target. A fast method based on short-time Fourier transform (STFT) and sequence reversing (SRT), that is, STFT-SRT, is proposed. In this method, STFT first employed to obtain velocity improve SNR without additional calculation. After that, SRT presented remove range migration (RM). Finally, (FT) conducted achieve in...

1999
Nizamettin Aydin Hugh S. Markus

Early and accurate detection of microemboli is important for monitoring of preventive therapy in stroke-prone patients. Embolic signals have large amplitude and show transient characteristics because of their reflectivity and size compared to the blood cells. One of the problems in detection of microemboli is the identification of an embolic signal caused by very small microemboli. The amplitud...

1997
Martin J. Bastiaans

The windowed Fourier transform of a time signal is considered, as well as a way to reconstruct the signal from a su ciently densely sampled version of its windowed Fourier transform using a Gabor representation; followingGabor, sampling occurs on a two-dimensional time-frequency lattice with equidistant time intervals and equidistant frequency intervals. In the limit of innitely dense sampling,...

Journal: :International Journal of Information and Communication Sciences 2017

1999
Soo-Chang Pei Min-Hung Yeh

Hadamard transform is an important tool in discrete signal processing. In this paper, we define the discrete fractional Hadamard transform which is a generalized one. The development of discrete fractional Hadamard is based upon the same spirit of discrete fractional Fourier transform.

2003
Soo-Chang Pei Jian-Jiun Ding

In this paper, we develop some methods to save the bandwidth required in the fractional domain. The fractional domain is the transformed domain of the fractional Fourier transform (FRFT). It is the intermediate of the time domain and the frequency domain. We find that, with the aid of the fractional Hilbert transform and other techniques, we can save 112 or 314 of the bandwidth in the fractiona...

1998
Sylvain Marchand

The purpose of this presentation is to demonstrate the practical interest of an original improvement of the classic Fourier analysis. The n-th order short-time Fourier Transform (FT) extends the classic short-time Fourier transform by also considering the first n signal derivatives. This technique greatly improves Fourier analysis precision not only in frequency and amplitude but also in time, ...

S. Gazor and A. M. Doosthoseini, S. Sadri,

During the last two decades, Maximum Likelihood estimation (ML) has been used to determine Direction Of Arrival (DOA) and signals propagated by the sources, using narrowband array signals. The algorithm fails in the case of wideband signals. As an attempt by the present study to overcome the problem, the array outputs are transformed into narrowband frequency bins, using short time Fourier tran...

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