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Background equalization method for reducing low-frequency noise level

A technology of low-frequency noise and equalization method, which is applied to radio wave measurement systems, instruments, etc., and can solve problems such as effect discounting and inability to suppress low-frequency noise well

Active Publication Date: 2021-06-08
NAT UNIV OF DEFENSE TECH
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Problems solved by technology

However, although these three methods can effectively reduce the non-uniform interference background in the time-frequency diagram, none of them can well suppress the low-frequency noise generated by the sonar receiving equipment; in addition, the performance of the OTA method and the S3PM method is more Rely on empirical parameters manually set, if the empirical parameters are not set properly, the effect of these two methods will be greatly reduced

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  • Background equalization method for reducing low-frequency noise level
  • Background equalization method for reducing low-frequency noise level
  • Background equalization method for reducing low-frequency noise level

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specific Embodiment approach

[0030] figure 1 It is the realization flowchart of the present invention. The specific implementation method comprises the following steps:

[0031] The first step is to take out the data row vector corresponding to a certain moment t in the time-frequency diagram (t=1,2,...,T, T represents the number of pixels in the time-frequency diagram in the time dimension) (if the corresponding data is a column vector is transposed as a row vector).

[0032] In the second step, the search gets all peaks and all valleys in the data row vector.

[0033] The third step, for a certain peak, search to find its left and right adjacent valleys that are the second closest to it, and then intercept the data between these two valleys, denoted as x(1),x(2),.. .,x(M), a total of M points, and record the largest and smallest valleys in this data as x min1 and x min2 , with the largest peak at x max .

[0034] If only 1 or 0 valleys are found on the left side of the peak, then x(1) takes the f...

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Abstract

The invention belongs to the technical field of sonar signal display, and relates to a background equalization method for reducing a low-frequency noise level, which designs a new background equalization mode, and comprises the following steps of: searching peak values and valley values in a time-frequency diagram image in a segmented manner, comparing the peak values and the valley values with preset thresholds, and outputting a background-equalized time-frequency diagram through point-by-point minimum value processing. The method provided by the invention has the beneficial effects that 1, the method does not need to manually set empirical parameters; and 2, compared with an S3PM method, an OTA method and a beam scanning feature method, the finally output background-balanced time-frequency graph has a lower average noise level at each frequency point, and particularly has a better noise suppression effect at a low frequency band, so that a line spectrum in the time-frequency graph can be more effectively detected and analyzed.

Description

technical field [0001] The invention belongs to the technical field of sonar signal display and relates to a background equalization method for reducing low-frequency noise level. Background technique [0002] An important method for sonar equipment to detect underwater targets is to use the radiation noise of underwater submarines, torpedoes and other targets as the received signal, and then analyze each frequency component in the time-frequency image (hereinafter referred to as the time-frequency image) of the received signal through detection and analysis. The "line spectrum" on the target (that is, the bright line on the frequency component that appears within a certain period of time, indicating that the frequency component has a relatively high amplitude during this period of time) is used to judge the presence and type of the target. Generally speaking, the line spectrum components of underwater target radiated noise are mainly concentrated in the lower frequency band...

Claims

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Application Information

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IPC IPC(8): G01S7/537
CPCG01S7/537
Inventor 朱家华张兵兵彭承彦徐国军吴艳群张卫华郭微胡正良朱敏
Owner NAT UNIV OF DEFENSE TECH
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