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Time-Frequency Analysis and Reconstruction Method of Shock Signals Based on Time Rearrangement Compression Transform

A technology of compression transformation and time-frequency analysis, applied in the field of time-frequency analysis of non-stationary signals, can solve the problems of poor time-frequency aggregation, large instantaneous frequency, large reconstruction error, etc., and achieve high time-frequency aggregation and strong anti-noise The effect of performance and strong readability

Active Publication Date: 2020-08-18
XI AN JIAOTONG UNIV
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Problems solved by technology

The theoretical analysis shows that, for this case, if the time-frequency analysis is performed according to the existing synchronous compression transform method, there will be a large instantaneous frequency estimation error, resulting in poor time-frequency aggregation and large reconstruction errors

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  • Time-Frequency Analysis and Reconstruction Method of Shock Signals Based on Time Rearrangement Compression Transform
  • Time-Frequency Analysis and Reconstruction Method of Shock Signals Based on Time Rearrangement Compression Transform
  • Time-Frequency Analysis and Reconstruction Method of Shock Signals Based on Time Rearrangement Compression Transform

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Embodiment Construction

[0033] The following combines an example to verify the effectiveness of the present invention in application, but this example is not intended to limit the present invention.

[0034] In order to illustrate the superiority of the time-rearrangement compression transform over the traditional short-time Fourier transform and synchronous compression transform, a noise-containing simulation signal is selected, and its time-domain waveform is as follows image 3 As shown in , it can be seen that the duration of the simulated signal in the time domain is relatively short, showing a certain impact characteristic. The expression of the simulated signal is:

[0035]

[0036] Phase in the formula f∈[0,1MHz], the frequency interval is 1KHz, that is, f=0:1000:1×10 6 Hz. f -1 (·) means inverse Fourier transform; noise means adding Gaussian white noise. The total duration of signal sampling is 1ms, the sampling frequency is 2MHz, the number of sampling points is N=2000, Gaussian wh...

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Abstract

The invention discloses a time-rearrangement compression transformation-based time-frequency analysis and reconstruction method of an impact-type signal. The method includes: 1) calculating short-timeFourier transform (STFT) of a to-be-analyzed discrete signal to obtain a corresponding time-frequency complex-matrix S<x>[n,k]; 2) carrying out short-time Fourier transform on the product of a time variable and the signal to obtain a time-frequency complex-matrix S<tx>[n,k]; 3) calculating a group delay estimation operator; 4) only rearranging the time-frequency complex-matrix S<x>[n,k], which isobtained in the step 1, along a time direction to obtain a time-frequency matrix V<x>[m,k] after time-rearrangement compression transformation; and 5) adding all rows of elements of the time-frequency matrix V<x>[m,k], which is obtained after time-rearrangement compression transformation, together to obtain a one-dimensional column vector, and then dividing the column vector by a mean value of awindow function, which is used by short-time Fourier transform, to obtain a frequency spectrum of a reconstructed signal. For analyzing the impact-type signal, the time-frequency graph aggregation obtained by time-rearrangement compression transformation to which the invention relates is higher than that of synchronous compression transformation, and good anti-noise performance is realized. Compared with traditional time-frequency rearrangement, the method has the advantages of reconstructability and a fast calculation speed.

Description

technical field [0001] The invention belongs to the field of time-frequency analysis of non-stationary signals, in particular to a method for time-frequency analysis and reconstruction of shock signals based on time rearrangement compression transformation. Background technique [0002] The time-frequency analysis method is a method of transforming a one-dimensional time-domain signal into a two-dimensional joint time-frequency domain (time-frequency domain) distribution, that is, considering the two variables of time and frequency, it can reveal that each component in the signal changes with time. or frequency variation. Due to the time-frequency joint characterization capability of time-frequency analysis, it is widely used in many fields including vibration signal analysis, speech signal processing, image processing, etc. There are two main research objectives of the time-frequency analysis method, one is to improve readability, and the other is to improve reconfigurabil...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F17/14G06F17/15
Inventor 曹宏瑞贺东陈雪峰訾艳阳席松涛
Owner XI AN JIAOTONG UNIV
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