Study on the Fractional Power Spectrum of the Improved 1-D Time-varying Sea Surface Model

The coprime discrete Fourier transform (DFT) filter banks provide an effective scheme of spectral sensing for wide-sense stationary (WSS) signals in case that the sampling rate is far lower than the Nyquist sampling rate. And the resolution of the coprime DFT filter banks in the Fourier domain (FD) is 2π/MN, where M and N are coprime. In this work, a digital fractional Fourier transform- (DFrFT-) based coprime filter banks spectrum sensing method is suggested. Our proposed method has the same sampling principle as the coprime DFT filter banks but has some advantages compared to the coprime DFT filter banks. Firstly, the fractional power spectrum of the chirp-stationary signals which are nonstationary in the FD can be sensed effectively by the coprime DFrFT filter banks because of the linear time-invariant (LTI) property of the proposed system in discrete-time Fourier domain (DTFD), while the coprime DFT filter banks can only sense the power spectrum of the WSS signals. Secondly, the coprime DFrFT filter banks improve the resolution from 2π/MN to 2π sin α/MN by combining the fractional filter banks theory with the coprime theory. Simulation results confirm the obtained analytical results.

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Detection of SMSP Jamming in Netted Radar System Based on Fractional Power Spectrum

2014 IEEE 17th International Conference on Computational Science and Engineering ◽

10.1109/cse.2014.197 ◽

2014 ◽

Author(s):

Yuan Zhao ◽

Dong-Ping Du ◽

Ahmed Abdalla Ali ◽

Bin Tang

Keyword(s):

Power Spectrum ◽

Fractional Power ◽

Radar System ◽

Fractional Power Spectrum

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The Fast Simulation of Scattering Characteristics from a Simplified Time Varying Sea Surface

International Journal of Antennas and Propagation ◽

10.1155/2015/815913 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Yiwen Wei ◽

Lixin Guo ◽

Xiao Meng

Keyword(s):

Realistic Model ◽

Short Wave ◽

Capillary Waves ◽

Long Waves ◽

Sea Surface ◽

Surface Model ◽

Time Varying ◽

Resonant Condition ◽

Scattering Coefficients ◽

Doppler Shifts

This paper aims at applying a simplified sea surface model into the physical optics (PO) method to accelerate the scattering calculation from 1D time varying sea surface. To reduce the number of the segments and make further improvement on the efficiency of PO method, a simplified sea surface is proposed. In this simplified sea surface, the geometry of long waves is locally approximated by tilted facets that are much longer than the electromagnetic wavelength. The capillary waves are considered to be sinusoidal line superimposing on the long waves. The wavenumber of the sinusoidal waves is supposed to satisfy the resonant condition of Bragg waves which is dominant in all the scattered short wave components. Since the capillary wave is periodical within one facet, an analytical integration of the PO term can be performed. The backscattering coefficient obtained from a simplified sea surface model agrees well with that obtained from a realistic sea surface. The Doppler shifts and width also agree well with the realistic model since the capillary waves are taken into consideration. The good agreements indicate that the simplified model is reasonable and valid in predicting both the scattering coefficients and the Doppler spectra.

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