Browsing by Subject "Time-frequency distributions"

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    Fractional Fourier domains
    (Elsevier BV, 1995-09) Özaktaş, Haldun M.; Aytür, O.
    It is customary to define the time-frequency plane such that time and frequency are mutually orthogonal coordinates. Representations of a signal in these domains are related by the Fourier transform. We consider a continuum of “fractional” domains making arbitrary angles with the time and frequency domains. Representations in these domains are related by the fractional Fourier transform. We derive transformation, commutation, and uncertainty relations among coordinate multiplication, differentiation, translation, and phase shift operators between domains making arbitrary angles with each other. These results have a simple geometric interpretation in time-frequency space.
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    Generalization of time-frequency signal representations to joint fractional Fourier domains
    (IEEE, 2005-09) Durak, L.; Özdemir, A. K.; Arıkan, Orhan; Song, I.
    The 2-D signal representations of variables rather than time and frequency have been proposed based on either Hermitian or unitary operators. As an alternative to the theoretical derivations based on operators, we propose a joint fractional domain signal representation (JFSR) based on an intuitive understanding from a time-frequency distribution constructing a 2-D function which designates the joint time and frequency content of signals. The JFSR of a signal is so designed that its projections on to the defining joint fractional Fourier domains give the modulus square of the fractional Fourier transform of the signal at the corresponding orders. We derive properties of the JFSR including its relations to quadratic time-frequency representations and fractional Fourier transformations. We present a fast algorithm to compute radial slices of the JFSR.
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    Zaman-frekans dağılımı için çekirdek kestirimi
    (IEEE, 2015-05) Deprem, Zeynel; Çetin, A. Enis
    Bu dokümanda çözünürlüğü yüksek ve çapraz terim içermeyen Cohen sınıfı bir Zaman-frekans (ZF) dağılımının, çekirdek kestirim yöntemi ile elde edilmesi tanıtılmaktadır. Çekirdek kestirimi, başlangıç taslak bir zaman-frekans dağılımının l1 normuna ait epigraf kümesi üzerine izdüşümü ile elde edilmektedir. Kestirilen çekirdek, sinyalin belirsizlik (Ambiguity) düzlemindeki hizalanması ile uyumlu ve çapraz terimleri içermeyecek bir filtreleme sağlamaktadır.