Abstract
The paper reveals the time-frequency symmetric property of the weighted-type fractional Fourier transform (WFRFT) by investigating the original definition of the WFRFT, and proposes a discrete algorithm of the WFRFT based on the weighted discrete Fourier transform (WDFT) algorithm with constraint conditions of the definition of the WFRFT and time-domain sampling. When the WDFT is considered in digital computation of the WFRFT, the Fourier transform in the definition of the WFRFT should be defined in frequency (Hz) but not angular frequency (rad/s). The sampling period Δt and sampling duration T should satisfy \(\Delta t = {T \mathord{\left/ {\vphantom {T N}} \right. \kern-\nulldelimiterspace} N} = {1 \mathord{\left/ {\vphantom {1 {\sqrt N }}} \right. \kern-\nulldelimiterspace} {\sqrt N }}\) when N-point DFT is utilized. Since Hermite-Gaussian functions are the best known eigenfunctions of the fractional Fourier transform (FRFT), digital computation based on eigendecomposition is also carried out as the additional verification and validation for the WFRFT calculation.
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References
Sejdic E, Djurovic I, Jiang J. Time-frequency feature representation using energy concentration: An overview of recent advances. Digit Signal Prog, 2009, 19: 153–183
Sejdic E, Djurovic I, Stankovic L. Fractional Fourier transform as a signal processing tool: An overview of recent developments. Signal Process, 2011, 91: 1351–1369
Cariolaro G, Erseghe T, Kraniauskas P, et al. A unified framework for the fractional Fourier transforms. IEEE Trans Signal Process, 1998, 46: 3206–3219
Cariolaro G, Erseghe T, Kraniauskas P, et al. Multiplicity of fractional Fourier transforms and their relationships. IEEE Trans Signal Process, 2000, 48: 227–241
Ran Q, Yeung D S, Tsang E C C, et al. General multifractional Fourier transform method based on the generalized permutation matrix group. IEEE Trans Signal Process, 2005, 53: 83–98
Tao R, Zhang F, Wang Y. Research progress on discretization of fractional Fourier transform. Sci China Ser F-Inf Sci, 2008, 51: 859–880
Ozaktas H M, Ankan O, Kutay M A, et al. Digital computation of the fractional Fourier transform. IEEE Trans Signal Process, 1996, 44: 2141–2150
Candan C, Kutay M A, Ozaktas H M. The discrete fractional Fourier transform. IEEE Trans Signal Process, 2000, 48: 1329–1337
Erseghe T, Cariolaro G. An orthonormal class of exact and simple DFT eigenvectors with a high degree of symmetry. IEEE Trans Signal Process, 2003, 51: 2527–2539
Pei S C, Hsue W L, Ding J J. Discrete fractional Fourier transform based on new nearly tridiagonal commuting matrices. IEEE Trans Signal Process, 2006, 54: 3815–3828
Santhanam B, McClellan J. The discrete rotational Fourier transform. IEEE Trans Signal Process, 1996, 44: 994–998
Pei S C, Yeh M H, Tseng C C. Discrete fractional Fourier transform based on orthogonal projections. IEEE Trans Signal Process, 1999, 47: 1335–1348
Shih C C. Fractionalization of Fourier transform. Opt Commun, 1995, 118: 495–498
Xia X G. On bandlimited signals with fractional Fourier transform. IEEE Signal Process Lett, 1996, 3: 72–74
Bhandari A, Zayed A I. Shift-invariant and sampling spaces associated with the fractional Fourier transform domain signal. IEEE Trans Signal Process, 2012, 60: 1627–1637
Feng Z, Ran T, Yue W. Multi-channel sampling theorems for band-limited signals with fractional Fourier transform. Sci China Ser E-Tech Sci, 2008, 51: 790–802
Shi J, Chi Y, Zhang N T. Multichannel sampling and reconstruction of bandlimited signals in fractional Fourier domain. IEEE Signal Process Lett, 2010, 17: 909–912
Bhandari A, Marziliano P. Sampling and reconstruction of sparse signals in fractional Fourier domain. IEEE Signal Process Lett, 2010, 17: 221–224
Tao R, Li B Z, Wang Y. Spectral analysis and reconstruction for periodic nonuniformly sampled signals in fractional Fourier domain. IEEE Trans Signal Process, 2007, 55: 3541–3547
Meng X, Tao R, Wang Y. Fractional Fourier domain analysis of decimation and interpolation. Sci China Ser F-Inf Sci, 2007, 50: 521–538
Tao R, Deng B, Zhang W Q, et al. Sampling and sampling rate conversion of band limited signals in the fractional Fourier transform domain. IEEE Trans Signal Process, 2008, 56: 158–171
Ozaktas H M, Mendlovic D. Fourier transforms of fractional order and their optical interpretation. Opt Commun, 1993, 101: 163–169
Liu S T, Zhang J D, Zhang Y. Properties of the fractionalization of a Fourier transform. Opt Commun, 1997, 133: 50–54
Yeung D S, Ran Q W, Tsang E C, et al. Complete way to fractionalize Fourier transform. Opt Commun, 2004, 230: 55–57
Lang J, Tao R, Ran Q W, et al. The multiple-parameter fractional Fourier transform. Sci China Ser F-Inf Sci, 2008, 51: 1010–1024
Candan C. On higher order approximations for Hermite-Gaussian functions and discrete fractional Fourier transforms. IEEE Signal Process Lett, 2007, 14: 699–702
Santhanam B, Santhanam T S. On discrete Gauss-Hermite functions and eigenvectors of the discrete Fourier transform. Signal Process, 2008, 88: 2738–2746
Hanna M T. Direct batch evaluation of optimal orthonormal eigenvectors of the DFT matrix. IEEE Trans Signal Process, 2008, 56: 2138–2143
Hanna M T, Seif N P A, AhmedWA E M. Discrete fractional Fourier transform based on the eigenvectors of tridiagonal and nearly tridiagonal matrices. Digit Signal Prog, 2008, 18: 709–727
Ran Q W, Zhang H Y, Zhang J, et al. Deficiencies of the cryptography based on multiple-parameter fractional Fourier transform. Opt Lett, 2009, 34: 2945
Lang J, Tao R, Wang Y. Image encryption based on the multiple-parameter discrete fractional Fourier transform and chaos function. Opt Commun, 2010, 283: 2092–2096
Lang J, Tao R, Wang Y. The discrete multiple-parameter fractional Fourier transform. Sci China Inf Sci, 2010, 53: 2287–2299
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Mei, L., Zhang, Q., Sha, X. et al. Digital computation of the weighted-type fractional Fourier transform. Sci. China Inf. Sci. 56, 1–12 (2013). https://doi.org/10.1007/s11432-013-4818-5
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DOI: https://doi.org/10.1007/s11432-013-4818-5