The fan-chirp transform for non-stationary harmonic signals

Weruaga, Luis; Képesi, Marián

doi:10.1016/j.sigpro.2007.01.006

Cited by 53 publications

(55 citation statements)

References 21 publications

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“…However, the fast FChT can be implemented as the Fourier transform of a time warped signal, which makes the speed dependent to the applied interpolation algorithm for time warping. Weruaga and Képesi performed an analysis on computing requirements for the fast FChT and approximated the computational complexity as N (7+log(N )) [39]. Dunn et al demonstrated that the choice of interpolation method gives a trade-off between the computational speed and the accuracy of the transformation [41].…”

Section: Discussionmentioning

confidence: 99%

“…The Fan Chirp transform was recently introduced into chirp analysis by Képesi and Weruaga [38], [39]. It has been employed in speech analysis [38], music representation [40], signal parameter estimation [41], and time-frequency representation of the chirps [39].…”

Section: The Fan Chirp Transform (Fcht)mentioning

confidence: 99%

“…It has been employed in speech analysis [38], music representation [40], signal parameter estimation [41], and time-frequency representation of the chirps [39]. However, the use of FChT has not been reported for ultrasound applications.…”

Section: The Fan Chirp Transform (Fcht)mentioning

confidence: 99%

“…1(D), where the resulting projection gives rise to the FChT spectrum. The observer can achieve the finest representation for linear frequency modulated chirps located with a fan geometry on the time-frequency plane, i. e. harmonically related chirps [39].…”

Section: The Fan Chirp Transform (Fcht)mentioning

confidence: 99%

See 3 more Smart Citations

Superharmonic imaging with chirp coded excitation: filtering spectrally overlapped harmonics

Harput

McLaughlan

Cowell

et al. 2014

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-Superharmonic imaging improves the spatial resolution by using the higher-order harmonics generated in tissue. The superharmonic component is formed by combining the third, fourth and fifth harmonics, which has low energy content and therefore poor SNR. This study uses coded excitation to increase the excitation energy. The SNR improvement is achieved on the receiver side by performing pulse compression with harmonic matched filters.The use of coded signals also introduces new filtering capabilities that are not possible with pulsed excitation. This is especially important when using wideband signals. For narrowband signals the spectral boundaries of the harmonics are clearly separated and thus easy to filter, however the available imaging bandwidth is underused. Wideband excitation is preferable for harmonic imaging applications to preserve axial resolution, but it generates spectrally overlapping harmonics that are not possible to filter in time and frequency domains. After pulse compression this overlap increases the range sidelobes, which appear as imaging artifacts and reduce the B-mode image quality. In this study, the isolation of higher-order harmonics was achieved in another domain by using the Fan Chirp Transform (FChT).To show the effect of excitation bandwidth in superharmonic imaging, measurements were performed by using linear frequency modulated chirp excitation with varying bandwidths of 10 − 50%. Superharmonic imaging was performed on a wire phantom using a wideband chirp excitation. Results were presented with and without applying the FChT filtering technique by comparing the spatial resolution and sidelobe levels. Wideband excitation signals achieved a better resolution as expected, however range sidelobes as high as −23 dB were observed for the superharmonic component of chirp excitation with 50% fractional bandwidth. The proposed filtering technique achieved > 50 dB range sidelobe suppression and improved the image quality without affecting the axial resolution.

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Section: Discussionmentioning

confidence: 99%

Section: The Fan Chirp Transform (Fcht)mentioning

confidence: 99%

Section: The Fan Chirp Transform (Fcht)mentioning

confidence: 99%

Section: The Fan Chirp Transform (Fcht)mentioning

confidence: 99%

See 2 more Smart Citations

Superharmonic imaging with chirp coded excitation: filtering spectrally overlapped harmonics

Harput

McLaughlan

Cowell

et al. 2014

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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show abstract

“…The Fractional Fourier Transform (FrFT) [8], [9] and Chirp Transform (CT) [10], [11] are suitable for linearly changing frequency components, whereas the Fan-Chirp Transform [12], [13] is suitable for signals with frequency components varying linearly on a fan geometry.…”

Section: Introductionmentioning

confidence: 99%

Efficient Spectral Estimation of Non-Stationary Harmonic Signals Using Harmonic Transform

Trzos

Khaddour²

2012

International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems

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Abstract-Non-stationary harmonic signals cannot be accurately represented by Fourier transform (FT). Fortunately, several methods for representing non-stationary harmonic signals exist including Fan-Chirp trasnform (FChT) or Harmonic transform (HT). This article is focused on the Harmonic transform and its computation. Estimation of slope of fundamental frequency change between analysed segments is essential for computation of the HT. The slope is estimated using several realisations of HT and comparing the spectral flatness. Optimisation of this procedure is presented in the article.

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Time–Frequency Analysis of Vietnamese Speech Inspired on Chirp Auditory Selectivity

Nguyen

Weruaga

2008

PRICAI 2008: Trends in Artificial Intelligence

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The fan-chirp transform for non-stationary harmonic signals

Cited by 53 publications

References 21 publications

Superharmonic imaging with chirp coded excitation: filtering spectrally overlapped harmonics

Superharmonic imaging with chirp coded excitation: filtering spectrally overlapped harmonics

Efficient Spectral Estimation of Non-Stationary Harmonic Signals Using Harmonic Transform

Time–Frequency Analysis of Vietnamese Speech Inspired on Chirp Auditory Selectivity

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