CN110082818A - A kind of ship noise robust identification method - Google Patents
A kind of ship noise robust identification method Download PDFInfo
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- CN110082818A CN110082818A CN201910367690.7A CN201910367690A CN110082818A CN 110082818 A CN110082818 A CN 110082818A CN 201910367690 A CN201910367690 A CN 201910367690A CN 110082818 A CN110082818 A CN 110082818A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H17/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
Abstract
The present invention relates to a kind of steady ship noise recognition methods, belong to ocean field of signal processing, the steps include: first to be standardized the signal of extraction, and then obtain the modulation spectrum of signal using filter and Fourier transformation combined treatment.Secondly, calculating modulation conspicuousness statistic, the calculation method of the statistic is the value of the maximum spectral line of amplitude in modulation spectrum divided by the average amplitude of modulation spectrum.Finally will modulation conspicuousness statistic with thresholding compared with, then think there is ship appearance if it is greater than thresholding, if a period of time it is interior continuously less than thresholding if think around without ship.Present invention utilizes this more stable physical quantitys of the modulating characteristic of ship noise, and compared to using signal power detection ship noise more steady, anti-interference is stronger.
Description
Technical field
The invention belongs to Yu Haiyang's field of signal processing, are related to a kind of ship noise robust identification method.
Background technique
The wind speed on sea and rainfall can be obtained by undersea noise inverting, this is the observation of ocean surface wind speed and rainfall
Provide a kind of new means.Noise in ocean is also influenced by ship around and mammal etc., Wind Speed Inversion and rainfall
It needs first to identify noise source before.The cry of mammal has transient state, is easier to distinguish.Surrounding ship occurs
When, the overall power level of ambient sea noise can improve, and whether may determine that surrounding accordingly with the presence of ship, this is also current
Common method.But this method also has its disadvantage: this method needs to be arranged the power inspection in some prior frequency range
Thresholding is surveyed, when noise power is more than detection threshold, it is believed that surrounding ship occur.This detection threshold is more difficult in practice to be obtained
It takes, has relationship with hydrophone sensitivity and ambient noise present level.Even if tracking current environment using adaptive method
Noise level, it is also possible to occur by wind speed increase and caused by noise level be lifted, be mistaken for the possibility of ship around.
Summary of the invention
For the presence for overcoming the problems, such as existing system, the present invention provides a kind of ship noise robust identification methods.This method
Steady identification is realized with the modulating characteristic of ship noise.
The present invention solve method used by its technical problem the following steps are included:
A kind of ship noise robust identification method, the described method comprises the following steps:
The first step, obtains one section of noise signal s that total length is T, and normalized operation obtains standardized noise letter
Number st；
Further, the step of normalizing operation is the DC component of removing signal first: st1=s-mean (s),
Wherein mean () expression takes averaging operation, then by the power normalization of signal: st=st1/std(st1), wherein std () is indicated
Standard deviation is taken to operate；
Second step, to signal stExecute bandpass filtering operation: sd1=filterbandpass(st), the frequency range of bandpass filtering is
3000Hz-5000Hz, then to square execution low-pass filtering of signal:Low-pass filtering
Upper limiting frequency is 200Hz, executes remove signal DC operation: s againd=sd2-mean(sd2)；
Third step, to signal sdFrequency spectrum P (f) is obtained using Fast Fourier Transform (FFT) (FFT), in 0.5Hz-200Hz range
Inside seek modulation conspicuousness statisticWherein max () expression is maximized operation；
4th step is set by modulation conspicuousness statistic T compared with thresholding D if modulation conspicuousness statistic T is more than or equal to
The thresholding D set, it is considered that surrounding is with the presence of ship；If continuously less than the thresholding D of setting in the period W of setting, that
Think around without ship.
Further, the setting method of the thresholding D are as follows: one section of noise signal when calculating separately ship and without ship
Modulate conspicuousness statistic T1(t) and T0(t), the value of thresholding D should ensure that at any time, D > T0(t), while in 85-95%
Time D < T1(t)。
Compared with the prior art, the invention has the advantages that:
The method of the present invention has used this more stable physical mechanism of the modulating characteristic of ship noise, can be more accurate
It identifies whether surrounding has ship appearance with stable, and then can be conducive to reject ship interference, so that utilizing marine environment
Noise Wind Speed Inversion and rainfall are more accurate.
Detailed description of the invention
Fig. 1 is ship noise modulation spectrogram；
Fig. 2 is wind or rainfall seanoise modulation spectrogram；
Fig. 3 is the method for the present invention step schematic diagram；
Fig. 4 has ship time noise signal and the method for the present invention processing result figure around being；
Fig. 5 is around without ship time noise signal and the method for the present invention processing result figure；
In figure, Fig. 4 (a) has ship time noise time-domain signal, and Fig. 4 (b) modulates conspicuousness statistic compared with thresholding, Fig. 4 (c)
Ship identification result；Fig. 5 (a) is without ship time noise time-domain signal, and Fig. 5 (b) modulates conspicuousness statistic compared with thresholding, Fig. 5 (c)
Ship identification result.
Specific embodiment
Technical solution of the present invention is further explained below by embodiment, but protection scope of the present invention not by
The limitation of embodiment in any form.
Embodiment 1
For inverting ocean surface wind speed and the hydrophone of rainfall generally to be laid on subsurface buoy, buoy, Argo and water from capacitance type
On the platforms such as lower aerodone.The influence of the vibration and noise of platform to hydrophone should be considered when laying.Under normal circumstances
Platform should carry out vibration and noise reducing work, including main floating body airflow design, change and shackle junction use rubber vibration isolation etc..
Furthermore generally it is connected by spring or elastic thread between hydrophone and platform, isolation platform vibration.
When having ship to pass through around hydrophone, the noise of ship can be received by hydrophone, if without effective
Identification and rejecting, can bring biggish error to ambient noise Wind Speed Inversion and rainfall result.The noise of ship compares in addition to itself
Environmental background noise power is high outer, there are one being significantly characterized in, the modulating action of the rotation of propeller to it.When surrounding has
When ship, hydrophone receives signal and can be described by following formula:
Wherein, vc(t) bring cavitation noise, v are rotated for propelleraIt (t) is ambient noise, ωsFor the rotation angular frequency of rotor shaft
Rate, miFor the index of modulation of i subharmonic modulation product, θsIt (t) is phase modulation, K is overtone order.It makes an uproar as shown in Figure 1 for ship
The modulation spectrogram of sound, it can be seen that have an apparent modulation spectral line in 12.8Hz.
The modulation signature of sea surface wind or rainfall bring noise not as ship noise, be illustrated in figure 2 wind or
The modulation spectrogram of rainfall seanoise, compared to Fig. 1 it can be seen that modulating characteristic is weaker in the signal of analysis.
In summary it analyzes, the invention proposes a kind of steady ship noise recognition methods, and the method define modulation
Conspicuousness statistic, the calculation method of the statistic are value being averaged divided by modulation spectrum of the maximum spectral line of amplitude in modulation spectrum
Amplitude, furthermore signal amplitude generates interference to calculated result in order to prevent, is standardized first before signal processing.
Specific operating procedure (see Fig. 3) includes: firstly, one section of noise signal s that acquisition total length is T, executes standard
Change operation and obtains standardized noise signal st.The size of T is traditionally arranged to be 10 seconds.The step of normalizing operation is to remove first
The DC component of signal: st1=s-mean (s), wherein mean () expression takes averaging operation, then by the power normalizing of signal
Change: st=st1/std(st1), wherein std () expression takes standard deviation to operate.Secondly, to signal stExecute bandpass filtering operation: sd1
=filterbandpass(st), the frequency range of bandpass filtering is 3000Hz-5000Hz, and the modulation of ship noise is special in this frequency range
Property is more obvious, this is also the frequency range that cavitation noise is more concentrated.Then to signal sd1Square execute low-pass filtering: The upper limiting frequency of low-pass filtering is 200Hz.It executes again and removes signal DC operation: sd=sd2-
mean(sd2).Third step, to signal sdFrequency spectrum P (f) is obtained using Fast Fourier Transform (FFT) (FFT), this has just obtained signal
Modulation spectrum.Modulation conspicuousness statistic is sought within the scope of 0.5Hz-200HzIts
Middle max () indicates to be maximized operation.Finally, by modulation conspicuousness statistic T compared with thresholding D, if modulation conspicuousness system
The thresholding D that T is more than or equal to setting is measured, it is considered that surrounding is with the presence of ship；If in the period W of setting continuously less than
The thresholding D of setting, it is considered that surrounding does not have ship.
The present invention is described in detail combined with specific embodiments below.
Embodiment 1
When having ship to pass through around, noise signal is obtained using hydrophone measurement, time domain waveform is shown in Fig. 4 (a), can be with
See that time domain waveform amplitude occurs one by small and big again by large and small process, shows have a ship at hydrophone
It is again separate.If judged from signal amplitude (representing noise power size) merely, at the beginning and end of ship noise is specific
Between more difficult determination.Modulation conspicuousness statistic is calculated using the method for the present invention to obtain as shown in Fig. 4 (b) as a result, wherein dotted line is
Thresholding, value 20, solid line are that modulation conspicuousness counts magnitude.It can be seen that modulating conspicuousness statistic near the 200th second
Value starts to be greater than 20.In the subsequent time, modulation conspicuousness statistic has respective time less than 20, and this is mainly due to ships to make an uproar
The variation of sound itself and ocean channel causes.It is respectively less than 20 within the time of period W=120 second of setting and just thinks ship
It is separate, therefore respective time modulation conspicuousness statistic is less than available effective solution of setting threshold value.Fig. 4 (c) is provided
Ship identification is as a result, wherein 0 indicate no ship, 1 indicate ship appearance.It can be seen that the technology of the present invention method is to ship
Noise has carried out effective identification.
Embodiment 2
Without ship time around, ambient sea noise time domain plethysmographic signal is shown in Fig. 5 (a).It is calculated and is modulated using the method for the present invention
Conspicuousness statistic is obtained as shown in Fig. 5 (b) as a result, wherein dotted line is thresholding, and value 20, solid line is modulation conspicuousness statistics
Magnitude.It can be seen that modulation conspicuousness statistics magnitude is not above thresholding in whole noise signal time, it is consistent with expection
It closes.Fig. 5 (c) gives recognition result, and output is 0, shows that no ship occurs.Further demonstrate the method for the present invention.
Claims (3)
1. a kind of ship noise robust identification method, it is characterised in that the described method comprises the following steps:
The first step, obtains one section of noise signal s that total length is T, and normalized operation obtains standardized noise signal st；
Second step, to signal stExecute bandpass filtering operation: sd1=filterbandpass(st), the frequency range of bandpass filtering is
3000Hz-5000Hz, then to square execution low-pass filtering of signal:Low-pass filtering
Upper limiting frequency is 200Hz, executes remove signal DC operation: s againd=sd2-mean(sd2)；
Third step, to signal sdFrequency spectrum P (f) is obtained using Fast Fourier Transform (FFT) (FFT), tune is sought within the scope of 0.5Hz-200Hz
Conspicuousness statistic T=max processed0.5≤f≤200(P)/mean0.5≤f≤200(P)；
4th step, by modulation conspicuousness statistic T compared with thresholding D, if modulation conspicuousness statistic T is more than or equal to setting
Thresholding D, it is considered that surrounding is with the presence of ship；If recognized in the period W of setting continuously less than the thresholding D of setting
There is no ship for surrounding.
2. a kind of ship noise robust identification method according to claim 1, it is characterised in that the normalizing operation
The step of for the DC component of removing signal first: st1=s-mean (s), wherein mean () expression take averaging operation, then will
The power normalization of signal: st=st1/std(st1), wherein std () expression takes standard deviation to operate.
3. a kind of ship noise robust identification method according to claim 1, it is characterised in that the setting side of the thresholding D
Method are as follows: the modulation conspicuousness statistic T of one section of noise signal when calculating separately ship and without ship1(t) and T0(t), thresholding
The value of D should ensure that at any time, D > T0(t), while in the time D < T of 85-95%1(t)。
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112712047A (en) * | 2021-01-08 | 2021-04-27 | 自然资源部第一海洋研究所 | Marine mammal echo positioning signal detection method based on image processing |
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