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Method for inhibiting cross terms in time-frequency division of multi-component linear frequency modulation (LFM) signals

A time-frequency distribution, multi-component technology, applied in the field of signal processing, can solve problems such as time-frequency resolution reduction

Active Publication Date: 2011-08-17
CHONGQING UNIV OF POSTS & TELECOMM
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Problems solved by technology

Although the Cohen-like time-frequency distribution can reduce cross-item interference to varying degrees, the time-frequency resolution will be reduced

Method used

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  • Method for inhibiting cross terms in time-frequency division of multi-component linear frequency modulation (LFM) signals
  • Method for inhibiting cross terms in time-frequency division of multi-component linear frequency modulation (LFM) signals
  • Method for inhibiting cross terms in time-frequency division of multi-component linear frequency modulation (LFM) signals

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Embodiment Construction

[0041] As mentioned above, the cross term can be suppressed by designing the optimal kernel function, and different time-frequency distributions can be obtained by choosing different kernel functions, and the nature of the kernel function determines the nature of the time-frequency distribution. Although this method can reduce cross-term interference to varying degrees, the time-frequency resolution will be reduced. Therefore, the time-frequency distribution of the multi-component signal is separated into the time-frequency distribution of the single-component signal one by one, which can not only maintain the time-frequency characteristics of the whole signal, but also avoid the influence of cross terms.

[0042] The cross term is equivalent to noise in the time-frequency distribution. Based on the subspace decomposition method of Singular Value Decomposition (SVD), the signal contaminated by noise can be decomposed into two parts: the subspace corresponding to the signal and ...

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Abstract

The invention discloses a method for inhibiting cross terms in the time-frequency distribution of multi-component linear frequency modulation (LFM) signals based on subspace decomposition, which belongs to the technical field of signal processing. In the method, a time-frequency distribution matrix comprising noises and the cross terms is decomposed into signal subspaces and noise subspaces by utilizing singular value decomposition (SVD)-based subspace decomposition. For the problem that the linear modulation signals occupy relatively more bandwidths to make singular values are reduced at relatively lower rates and cannot be separated from the noises effectively, an angle of inclination of the time-frequency distribution of the signals can be obtained by utilizing Wigner-Hough transform. The time-frequency distribution of the signals is rotated according to the obtained angle so as to be parallel to a time base. The method is characterized in that: the singular values are rapidly decreased to zero, and then the signal sub-spaces can be separated effectively. By the method, the cross terms and the noises in the time-frequency distribution of the multi-component LFM signals are inhibited without reducing time-frequency resolution; therefore, the method is vast in application prospect.

Description

Technical field: [0001] The invention relates to the field of signal processing, in particular to a method capable of suppressing cross items in the time-frequency distribution of multi-component Linear Frequency Modulation (LFM) signals. Background technique [0002] Chirp signal is a typical non-stationary signal, which is widely used in communication, radar, sonar and biomedical systems. For a non-stationary signal, its instantaneous frequency varies with time. As a classic signal analysis tool, Fourier Transform (FT: Fourier Transform) is based on the assumption that the signal is globally stable, it is a complete frequency representation, and it cannot provide any time information, that is, it can only provide the frequency components contained in the signal , but cannot reveal when these frequency components occur. The time domain and the frequency domain are two relatively independent signal description domains. No matter which representation, it cannot explain the ...

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Application Information

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IPC IPC(8): H04L25/03
Inventor 张天骐金翔代少升李越雷侯瑞玲庞统赵德芳
Owner CHONGQING UNIV OF POSTS & TELECOMM
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