A Transient Weak Signal Detection Method Based on Nonlinear Time Squeezing Time-Frequency Transform
A technology for detecting weak signals and transient signals, which is applied in seismic signal processing, measuring devices, geophysical measurements, etc., can solve the problems that nonlinear squeezing time-frequency transformation is not suitable for detecting strong frequency signals, etc., and achieves easy implementation and improved Good time resolution and operability
Active Publication Date: 2022-03-08
CHINA NAT OFFSHORE OIL CORP +1
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Problems solved by technology
[0006] (1) Non-linear squeezing time-frequency transformation is not suitable for detecting signals with strong frequency;
[0007] (2) Time synchronization squeeze transformation is not suitable for signals with weak components
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Embodiment 1
[0048] In this embodiment, the synthetic shock signal is used to test the effectiveness of the method of the present invention.
[0049] As shown in Fig. 1(a), an impulse response occurs at 0.25s and 0.75s, and their magnitudes are 2 and 0.02, respectively. The sampling frequency of the signal is 200Hz, and the sampling time is 1s. This example presents the time-frequency results of the short-time Fourier transform (Fig. 1(b)), the time-synchronously squeezed transform (Fig. 1(c)) and the nonlinear time-squeezed transform (Fig. 1(d)) . Through observation, it can be obtained that the energy in the time direction of the time-frequency spectrum of the time-synchronous squeeze transform is more concentrated than that of the short-time Fourier transform, but the existence of weak signals cannot be detected. However, as a result of the method of the present invention, components with weak energy can be accurately and clearly detected.
[0050] Then this embodiment provides a sim...
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The present invention relates to a weak signal detection method based on nonlinear time-squeezing transformation, comprising: 1) using the short-time Fourier transform formula to transform the transient signal f(t) to be detected to obtain its short-time Fourier transform Result; 2) Estimating the group delay operator based on the impulse signal to obtain the group delay operator; 3) Using the group delay operator in step 2) and the transient signal to be detected in step 1) The short-time Fourier transform coefficient calculates the time-frequency result of nonlinear time-squeezing transformation, and obtains the time-frequency coefficient at the time when the transient signal to be detected occurs according to the time-frequency result. The nonlinear time-squeezing time-frequency transformation proposed by the present invention can clearly detect signal components with relatively weak energy in the time-frequency domain. The technical scheme is easy to realize and has strong operability. Therefore, it can be widely used in the detection field of transient weak signals.
Description
technical field [0001] The invention belongs to the field of signal processing in geophysical prospecting, and relates to a detection method for transient weak signals, in particular to a detection method for transient weak signals based on nonlinear time-squeezing time-frequency transformation. Background technique [0002] The phenomenon of weak signal is very common in practical engineering, and its detection and identification is an important task. Aiming at the detection of weak signals, there have been many theoretical and applied researches. The more commonly used methods include wavelet transform, curvelet transform and so on. However, the wavelet threshold method lacks effective protection of the signal amplitude when suppressing random noise, and its detection effect on weak signals is not ideal; while the curvelet threshold method can effectively detect weak signals, but the results often contain some " Artifacts". [0003] In the new technology, some scholars ...
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IPC IPC(8): G01V1/30
CPCG01V1/307G01V2210/63
Inventor 王清振高静怀张金淼姜秀娣朱振宇翁斌丁继才孙文博桑淑云李振赵小龙李超郑颖
Owner CHINA NAT OFFSHORE OIL CORP