CN113884986B - Beam focusing enhanced strong impact signal space-time domain joint detection method and system - Google Patents

Beam focusing enhanced strong impact signal space-time domain joint detection method and system Download PDF

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CN113884986B
CN113884986B CN202111464885.7A CN202111464885A CN113884986B CN 113884986 B CN113884986 B CN 113884986B CN 202111464885 A CN202111464885 A CN 202111464885A CN 113884986 B CN113884986 B CN 113884986B
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sound source
source signal
signal
array
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CN113884986A (en
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曹祖杨
张凯强
黄明
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Hangzhou Crysound Electronics Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/18—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using ultrasonic, sonic, or infrasonic waves
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
    • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
    • G10L25/48—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 specially adapted for particular use
    • G10L25/51—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 specially adapted for particular use for comparison or discrimination

Abstract

The invention discloses a method and a system for detecting strong impact signal space-time domain combination by enhancing beam focusing, wherein the method comprises the following steps: s1, calculating the time delay of each array element in the microphone array relative to the time delay of the sound source signal received by the array center, and accordingly constructing an array flow pattern matrix; s2, based on the array flow pattern matrix, obtaining the space energy distribution through the beam forming space scanning, and further determining the sound source signal position; s3, based on the sound source signal position and the microphone array, beam forming focusing is carried out to obtain an enhanced sound source signal of the sound source signal through time-frequency domain enhancement; and S4, calculating a likelihood ratio function based on the enhanced sound source signal by a maximum likelihood detection method, and judging whether the enhanced sound source signal has the impact signal according to the likelihood ratio function. The method can perform beam forming focusing on the sound source after the position of the sound source is determined, and judge whether a strong impact signal exists in the sound source through a maximum likelihood detection method, so that a false alarm phenomenon is avoided, and the detection reliability and the robustness are high.

Description

Beam focusing enhanced strong impact signal space-time domain joint detection method and system
Technical Field
The invention belongs to the technical field of impact signal detection, and particularly relates to a method and a system for detecting strong impact signals in a space-time domain combined manner by enhancing beam focusing.
Background
Acoustic imaging (acoustic imaging) is based on a microphone array measurement technology, and is characterized in that the position of a sound source is determined according to a phased array principle by measuring the phase difference of signals of sound waves in a certain space reaching each microphone, the amplitude of the sound source is measured, and the distribution of the sound source in the space is displayed in an image mode, namely a cloud image-sound image of the spatial sound field distribution is obtained, wherein the intensity is represented by the color and the brightness of the image. Therefore, the positioning research on the sound source position is mature at present, but the research on the sound source property is less at present, so that the false alarm phenomenon occurs in the detection of the strong impact signal, and the detection reliability is low.
For example, chinese patent publication No. CN113126028A discloses a noise source positioning method based on multiple microphone arrays. M microphone sensors are selected to construct an annular microphone array, one microphone sensor is arranged to serve as a reference microphone sensor, an array coordinate system is established by the reference microphone sensor, the other M-1 microphone sensors are arranged around the reference microphone sensor, and D sound sources are arranged in a cabin; obtaining relative transfer functions from D sound sources to each microphone sensor, and constructing an array flow pattern matrix of the annular microphone array; further introducing the linear distance between the sound source and the reference microphone sensor, the azimuth angle of the sound source relative to the reference microphone sensor and the sound source frequency to construct an array flow pattern near-field model; estimating the azimuth angle of each sound source relative to the reference microphone sensor by adopting a MUSIC algorithm; more than two identical annular microphone arrays are preset in a cabin, azimuth angles of a sound source relative to each annular microphone array relative to a reference microphone sensor are estimated, the distance from the sound source to each annular microphone array is solved by using a least square method overall, and then sound source position information is acquired.
Therefore, a scheme is needed to avoid noise interference and stably and reliably detect short-time strong impact signals such as metal collision, power supply line discharge and the like.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the wave beam focusing enhanced strong impact signal space-time domain joint detection method and system, which can not only determine the position of a sound source, but also judge whether the strong impact signal exists in the sound source after determining the position of the sound source, eliminate the interference of noise, avoid the false alarm phenomenon in the detection of the strong impact signal, and have high detection reliability and strong robustness.
The invention adopts the following technical scheme:
the strong impact signal space-time domain joint detection method of beam focusing enhancement comprises the following steps:
s1, calculating the time delay of each array element in the microphone array relative to the time delay of the sound source signal received by the array center, and accordingly constructing an array flow pattern matrix;
s2, based on the array flow pattern matrix, obtaining the space energy distribution through the beam forming space scanning, and further determining the sound source signal position;
s3, based on the sound source signal position and the microphone array, beam forming focusing is carried out to obtain an enhanced sound source signal of the sound source signal through time-frequency domain enhancement;
and S4, calculating a likelihood ratio function based on the enhanced sound source signal by a maximum likelihood detection method, and judging whether the enhanced sound source signal has the impact signal according to the likelihood ratio function.
Preferably, step S1 includes the steps of:
s1.1, calculating to obtain the time delay of each array element for receiving a sound source signal by taking the center of the microphone array as a reference center;
s1.2, obtaining the phase shift of each array element receiving sound source signals according to the time delay of each array element receiving sound source signals;
s1.3, obtaining an array flow pattern matrix of each array element according to the phase shift of the sound source signal received by each array element.
Preferably, in step S1.1, a two-dimensional planar microphone array is used, and the time delay of each array element for receiving the sound source signal is calculated as:
Figure 201504DEST_PATH_IMAGE001
（1），
wherein the content of the first and second substances,
Figure 23704DEST_PATH_IMAGE002
and
Figure 334600DEST_PATH_IMAGE003
respectively representing the sound source signal relative to
Figure 464230DEST_PATH_IMAGE004
A plane surface,
Figure 216285DEST_PATH_IMAGE005
The angle of incidence of the plane is such that,
Figure 242010DEST_PATH_IMAGE006
which is indicative of the speed of sound,
Figure 243464DEST_PATH_IMAGE007
and
Figure 848889DEST_PATH_IMAGE008
respectively represent
Figure 48926DEST_PATH_IMAGE009
Of array elements
Figure 947350DEST_PATH_IMAGE005
Direction coordinates and
Figure 639362DEST_PATH_IMAGE004
the coordinates of the direction are shown in the figure,
Figure 173112DEST_PATH_IMAGE010
，
Figure 103022DEST_PATH_IMAGE011
indicating the number of array elements.
Preferably, in step S1.2, the phase shift of the sound source signal received by each array element is calculated by the following formula:
Figure 267287DEST_PATH_IMAGE012
（2），
wherein the content of the first and second substances,
Figure 712174DEST_PATH_IMAGE013
which is indicative of the frequency of the signal,
Figure 721719DEST_PATH_IMAGE014
representing an imaginary operator.
Preferably, the array flow pattern matrix of each array element in step S1.3 is:
Figure DEST_PATH_IMAGE016A
（3），
wherein the content of the first and second substances,
Figure 332566DEST_PATH_IMAGE017
to represent
Figure 74257DEST_PATH_IMAGE005
The discrete angle of the dimension(s) is,
Figure 334338DEST_PATH_IMAGE018
to represent
Figure 819677DEST_PATH_IMAGE004
The discrete angle of the dimension(s) is,
Figure 114392DEST_PATH_IMAGE020
，
Figure 292563DEST_PATH_IMAGE022
，
Figure 977623DEST_PATH_IMAGE023
to represent
Figure 391286DEST_PATH_IMAGE004
The number of the dimension grids is increased,
Figure 648830DEST_PATH_IMAGE024
to represent
Figure 122537DEST_PATH_IMAGE005
And (5) maintaining the number of grids. Preferably, step S2 includes the steps of:
s2.1, based on an array flow pattern matrix, and forming space scanning through a beam to obtain space energy distribution:
Figure 232575DEST_PATH_IMAGE025
（4），
wherein the content of the first and second substances,
Figure 387613DEST_PATH_IMAGE026
which indicates the lower limit of the processing band,
Figure 391341DEST_PATH_IMAGE027
the upper limit of the processing band is shown,
Figure 911315DEST_PATH_IMAGE028
is composed of
Figure 633284DEST_PATH_IMAGE029
Performing Fourier transform on the received signals of the array elements to obtain frequency domain representation;
s2.2, determining the spatial position of the sound source signal based on the spatial energy distribution and by maximum scanning
Figure 264116DEST_PATH_IMAGE030
。
Preferably, step S3 includes the steps of:
s3.1, pointing the microphone array to a spatial position
Figure 60034DEST_PATH_IMAGE030
To obtain a beam focusing signal, the calculation formula is:
Figure 875543DEST_PATH_IMAGE031
（5）；
s3.2, carrying out inverse Fourier transform on the wave beam focusing signal to obtain an enhanced sound source signal of the sound source signal enhanced by the time-frequency domain, wherein the calculation formula is as follows:
Figure 193130DEST_PATH_IMAGE032
（6）。
preferably, step S4 includes the steps of:
s4.1, acquiring n sample values in the enhanced sound source signal;
s4.2, calculating the one-dimensional probability density of the n sample values when only noise exists, wherein the calculation formula is as follows:
Figure 17866DEST_PATH_IMAGE033
（8），
wherein the content of the first and second substances,
Figure 933870DEST_PATH_IMAGE034
which represents the ith sample point, is,
Figure 326805DEST_PATH_IMAGE035
which is representative of the noise signal(s),
Figure 633153DEST_PATH_IMAGE036
representing the noise power;
s4.3, deriving a first joint probability density of the n sample values when only noise exists according to the formula (8), wherein the calculation formula is as follows:
Figure 933684DEST_PATH_IMAGE037
（9），
wherein the content of the first and second substances,
Figure 766511DEST_PATH_IMAGE038
representing a first joint probability density;
s4.4, when the impact signal exists, deducing and obtaining a second combined probability density of the n sample values according to the formula (8), wherein the calculation formula is as follows:
Figure 799189DEST_PATH_IMAGE039
（10），
wherein, the first and the second end of the pipe are connected with each other,
Figure 717466DEST_PATH_IMAGE040
a second combined probability density is represented that is,
Figure 821688DEST_PATH_IMAGE041
which is indicative of a shock signal,
Figure 617344DEST_PATH_IMAGE042
representing the impulse signal power;
s4.5, based on the formulas (9) and (10), calculating to obtain a likelihood ratio function;
and S4.6, judging whether the likelihood ratio function is greater than a detection threshold value, if so, judging that an impact signal exists, otherwise, judging that the impact signal does not exist.
Preferably, in step S4.5, the likelihood ratio function is:
Figure 211136DEST_PATH_IMAGE043
（11）。
correspondingly, the system for detecting the space-time domain combination of the strong impact signals of the beam focusing enhancement is also provided, and comprises a matrix construction module, a positioning module, a signal enhancement module and a judgment module which are sequentially connected based on the detection method;
the matrix construction module is used for calculating the time delay of each array element in the microphone array relative to the time delay of the sound source signal received by the array center so as to construct an array flow pattern matrix;
the positioning module is used for obtaining spatial energy distribution through beam forming spatial scanning based on the array flow pattern matrix so as to determine the position of a sound source signal;
the signal enhancement module is used for carrying out beam forming focusing on the basis of the sound source signal position and the microphone array so as to obtain an enhanced sound source signal of the sound source signal enhanced by the time-frequency domain;
and the judging module is used for calculating a likelihood ratio function based on the enhanced sound source signal by a maximum likelihood detection method, and judging whether the enhanced sound source signal has an impact signal according to the likelihood ratio function.
The invention has the beneficial effects that:
the method not only can determine the position of the sound source, but also can perform beam forming focusing on the sound source after determining the position of the sound source, and judges whether a strong impact signal exists in the sound source through a maximum likelihood detection method, namely, joint detection of a space domain and a time domain is adopted, so that the interference of noise is eliminated, the false alarm phenomenon in the detection of the strong impact signal is avoided, and the detection reliability and the robustness are high.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of the method for detecting the space-time domain combination of strong impact signals with enhanced beam focusing according to the present invention;
FIG. 2 is a schematic diagram of a two-dimensional microphone array geometry;
FIG. 3 is a schematic diagram of spatial energy distribution;
FIG. 4 is a diagram illustrating the results of beam focus enhancement;
fig. 5 is a schematic structural diagram of a beam focusing enhanced strong impact signal space-time domain joint detection system according to the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
The first embodiment is as follows:
referring to fig. 1, the present embodiment provides a method for detecting a strong impulse signal space-time domain joint with enhanced beam focusing, including the steps of:
s1, calculating the time delay of each array element in the microphone array relative to the time delay of the sound source signal received by the array center, and accordingly constructing an array flow pattern matrix;
s2, based on the array flow pattern matrix, obtaining the space energy distribution through the beam forming space scanning, and further determining the sound source signal position;
s3, based on the sound source signal position and the microphone array, beam forming focusing is carried out to obtain an enhanced sound source signal of the sound source signal through time-frequency domain enhancement;
and S4, calculating a likelihood ratio function based on the enhanced sound source signal by a maximum likelihood detection method, and judging whether the enhanced sound source signal has the impact signal according to the likelihood ratio function.
Therefore, the invention can not only determine the position of the sound source, but also perform beam forming focusing on the sound source after determining the position of the sound source, and judge whether the sound source has strong impact signals through a maximum likelihood detection method, namely, the joint detection of a space domain and a time domain is adopted, the interference of noise is eliminated, the false alarm phenomenon in the detection of the strong impact signals is avoided, and the detection reliability and the robustness are high. The short-time strong impact signals such as metal collision, power supply line discharge and the like can be effectively detected.
Specifically, the method comprises the following steps:
consider a two-dimensional planar microphone array with microphone elements distributed in the xy plane. Under the assumption of plane waves, a sound source is incident into a microphone array at a certain angle, and the time for the sound wave to propagate to each microphone element is different. And considering narrowband signal or wideband signal frequency domain processing, the time delay of the sound source signal, i.e. the phase shift of the signal. Therefore, step S1 includes the steps of:
s1.1, with the center of a microphone array as a reference center, calculating the time delay of each array element for receiving a sound source signal, wherein the calculation formula is as follows:
Figure 960918DEST_PATH_IMAGE001
（1），
wherein the content of the first and second substances,
Figure 931148DEST_PATH_IMAGE002
and
Figure 348354DEST_PATH_IMAGE003
respectively representing the sound source signal relative to
Figure 847468DEST_PATH_IMAGE004
A plane surface,
Figure 678021DEST_PATH_IMAGE005
The angle of incidence of the plane is such that,
Figure 796149DEST_PATH_IMAGE006
which is indicative of the speed of sound,
Figure 458075DEST_PATH_IMAGE007
and
Figure 331353DEST_PATH_IMAGE008
respectively represent
Figure 819841DEST_PATH_IMAGE009
Of array elements
Figure 600715DEST_PATH_IMAGE005
Direction coordinates and
Figure 992513DEST_PATH_IMAGE004
the coordinates of the direction are shown in the figure,
Figure 833430DEST_PATH_IMAGE010
，
Figure 576258DEST_PATH_IMAGE011
the number of array elements is shown, and can be specifically referred to fig. 2.
S1.2, obtaining the phase shift of each array element receiving sound source signals according to the time delay of each array element receiving sound source signals, wherein the calculation formula is as follows:
Figure 364086DEST_PATH_IMAGE012
（2），
wherein the content of the first and second substances,
Figure 735024DEST_PATH_IMAGE013
which is indicative of the frequency of the signal,
Figure 622209DEST_PATH_IMAGE014
representing an imaginary operator.
S1.3, obtaining an array flow pattern matrix of each array element according to the phase shift of the sound source signal received by each array element, wherein the array flow pattern matrix is as follows:
Figure DEST_PATH_IMAGE045
（3），
wherein, the two-dimensional space is gridded to obtain discrete two-dimensional angles,
Figure 445808DEST_PATH_IMAGE017
to represent
Figure 207966DEST_PATH_IMAGE005
The discrete angle of the dimension(s) is,
Figure 698990DEST_PATH_IMAGE018
to represent
Figure 757076DEST_PATH_IMAGE004
The discrete angle of the dimension(s) is,
Figure 536813DEST_PATH_IMAGE046
，
Figure DEST_PATH_IMAGE047
，
Figure 869705DEST_PATH_IMAGE023
to represent
Figure 215236DEST_PATH_IMAGE004
The number of the dimension grids is increased,
Figure 709803DEST_PATH_IMAGE024
to represent
Figure 711257DEST_PATH_IMAGE005
And (5) maintaining the number of grids.
The beam forming is a spatial filtering method, which can obtain an enhanced signal in a certain direction of a space, and the target azimuth angle can be obtained by the known array flow pattern matrix through the spatial scanning of the beam forming.
In step S2, the method includes the steps of:
s2.1, based on the array flow pattern matrix, and forming a space scanning through a beam to obtain a space energy distribution (shown in a reference figure 3):
Figure 706894DEST_PATH_IMAGE025
（4），
wherein the content of the first and second substances,
Figure 15254DEST_PATH_IMAGE026
which indicates the lower limit of the processing band,
Figure 8618DEST_PATH_IMAGE027
the upper limit of the processing band is shown,
Figure 294105DEST_PATH_IMAGE028
is composed of
Figure 437642DEST_PATH_IMAGE029
Performing Fourier transform on the received signals of the array elements to obtain frequency domain representation;
s2.2, determining the spatial position of the sound source signal based on the spatial energy distribution and by maximum scanning
Figure 757765DEST_PATH_IMAGE030
。
Assuming that the spatial position of the sound source signal is obtained by the second calculation
Figure 594134DEST_PATH_IMAGE030
Since a high signal-to-noise ratio signal of the sound source signal can be obtained by the beamforming focusing, the step S3 includes the steps of:
s3.1, pointing the microphone array to a spatial position
Figure 304601DEST_PATH_IMAGE030
To obtain a beam focusing signal, the calculation formula is:
Figure 642041DEST_PATH_IMAGE031
（5）；
s3.2, carrying out inverse Fourier transform on the wave beam focusing signal to obtain an enhanced sound source signal of the sound source signal enhanced by a time-frequency domain, and referring to FIG. 4, wherein a part with large amplitude in the graph is the enhanced sound source signal, a part with small amplitude is the original pulse sound source signal, and the calculation formula is as follows:
Figure 692037DEST_PATH_IMAGE032
（6）。
the maximum likelihood detection method is used for detecting enhanced sound source signals enhanced by time-frequency domain
Figure 558362DEST_PATH_IMAGE035
Which is representative of the noise signal(s),
Figure 192343DEST_PATH_IMAGE041
representing the impact signal. In this way, two decision events can be formed:
Figure 802316DEST_PATH_IMAGE048
（7）
both the impulse signal and the noise signal can be assumed to be stationary random signals following a gaussian distribution.
Therefore, step S4 specifically includes the following steps:
s4.1, acquiring n sample values in the enhanced sound source signal,
Figure DEST_PATH_IMAGE049
；
s4.2, calculating the one-dimensional probability density of the n sample values when only noise exists, wherein the calculation formula is as follows:
Figure 441239DEST_PATH_IMAGE033
（8），
wherein the content of the first and second substances,
Figure 478465DEST_PATH_IMAGE034
which represents the ith sample point, is,
Figure 101207DEST_PATH_IMAGE036
representing the noise power;
s4.3, deriving a first joint probability density of the n sample values when only noise exists according to the formula (8), wherein the calculation formula is as follows:
Figure 780450DEST_PATH_IMAGE037
（9），
wherein the content of the first and second substances,
Figure 867355DEST_PATH_IMAGE038
representing a first joint probability density;
s4.4, when the impact signal exists, deducing and obtaining a second combined probability density of the n sample values according to the formula (8), wherein the calculation formula is as follows:
Figure 216428DEST_PATH_IMAGE039
（10），
wherein the content of the first and second substances,
Figure 185521DEST_PATH_IMAGE040
a second combined probability density is represented that is,
Figure 511198DEST_PATH_IMAGE041
which is indicative of a shock signal,
Figure 780505DEST_PATH_IMAGE042
representing the impulse signal power;
s4.5, based on the expressions (9) and (10), calculating to obtain a likelihood ratio function, wherein the likelihood ratio function is as follows:
Figure 362796DEST_PATH_IMAGE043
（11）。
s4.6, when the likelihood ratio function is larger than a certain value, it can be considered that
Figure 694552DEST_PATH_IMAGE050
The event is established:
Figure DEST_PATH_IMAGE051
（12）
order to
Figure 450018DEST_PATH_IMAGE052
（13）
When in use
Figure 183619DEST_PATH_IMAGE053
（14）
Consider that
Figure 999128DEST_PATH_IMAGE050
An event occurs, i.e. a shock signal is present.
When in use
Figure DEST_PATH_IMAGE054
（15）
Consider that
Figure DEST_PATH_IMAGE055
An event occurs, i.e. there is no impact signal.
Figure DEST_PATH_IMAGE056
、
Figure DEST_PATH_IMAGE057
All represent detection threshold values, through control
Figure DEST_PATH_IMAGE058
The detection probability and the false alarm probability of the impact signal can be adjusted, the detection reliability is improved, and the robustness is strong.
The second embodiment:
referring to fig. 5, the present embodiment provides a beam focusing enhanced high impact signal space-time domain joint detection system, which includes a matrix construction module, a positioning module, a signal enhancement module, and a determination module, which are sequentially connected, based on the detection method described in the first embodiment;
the matrix construction module is used for calculating the time delay of each array element in the microphone array relative to the time delay of the sound source signal received by the array center so as to construct an array flow pattern matrix;
the positioning module is used for obtaining spatial energy distribution through beam forming spatial scanning based on the array flow pattern matrix so as to determine the position of a sound source signal;
the signal enhancement module is used for carrying out beam forming focusing on the basis of the sound source signal position and the microphone array so as to obtain an enhanced sound source signal of the sound source signal enhanced by the time-frequency domain;
and the judging module is used for calculating a likelihood ratio function based on the enhanced sound source signal by a maximum likelihood detection method, and judging whether the enhanced sound source signal has an impact signal according to the likelihood ratio function.
It should be noted that, similar to the embodiments, the strong impact signal detection system of the focus enhancement time-frequency domain provided in this embodiment is not described herein again.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention by those skilled in the art should fall within the protection scope of the present invention without departing from the design spirit of the present invention.

Claims (10)

1. The strong impact signal space-time domain joint detection method for beam focusing enhancement is characterized by comprising the following steps of:
s1, calculating the time delay of each array element in the microphone array relative to the time delay of the sound source signal received by the array center, and accordingly constructing an array flow pattern matrix;
s2, based on the array flow pattern matrix, obtaining the space energy distribution through the beam forming space scanning, and further determining the sound source signal position;
s3, based on the sound source signal position and the microphone array, beam forming focusing is carried out to obtain an enhanced sound source signal of the sound source signal through time-frequency domain enhancement;
s4, calculating to obtain a likelihood ratio function based on the enhanced sound source signal by a maximum likelihood detection method, and judging whether an impact signal exists in the enhanced sound source signal according to the likelihood ratio function;
in step S4, the method includes the steps of:
s4.1, acquiring n sample values in the enhanced sound source signal;
s4.2, calculating the one-dimensional probability density of the n sample values when only noise exists;
s4.3, deducing to obtain a first combined probability density of the n sample values only with noise based on the one-dimensional probability density;
s4.4, deducing and obtaining a second combined probability density of the n sample values when the impact signal exists based on the one-dimensional probability density;
s4.5, calculating to obtain a likelihood ratio function based on the first joint probability density and the second joint probability density;
and S4.6, judging whether the likelihood ratio function is greater than a detection threshold value, if so, judging that an impact signal exists, otherwise, judging that the impact signal does not exist.
2. The method for detecting spatial-temporal combination of strong impulse signals with enhanced beam focusing according to claim 1, wherein step S1 includes the steps of:
s1.1, calculating to obtain the time delay of each array element for receiving a sound source signal by taking the center of the microphone array as a reference center;
s1.2, obtaining the phase shift of each array element receiving sound source signals according to the time delay of each array element receiving sound source signals;
s1.3, obtaining an array flow pattern matrix of each array element according to the phase shift of the sound source signal received by each array element.
3. The method for detecting the space-time domain combination of the strong impact signals with the enhanced beam focusing according to claim 2, wherein in step S1.1, a two-dimensional planar microphone array is adopted, the time delay of each array element for receiving the sound source signal is calculated as:
Figure DEST_PATH_IMAGE001
（1），
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE002
and
Figure DEST_PATH_IMAGE003
respectively representing the sound source signal relative to
Figure DEST_PATH_IMAGE004
A plane surface,
Figure DEST_PATH_IMAGE005
The angle of incidence of the plane is such that,
Figure DEST_PATH_IMAGE006
which is indicative of the speed of sound,
Figure DEST_PATH_IMAGE007
and
Figure DEST_PATH_IMAGE008
respectively represent
Figure DEST_PATH_IMAGE009
Of array elements
Figure 142758DEST_PATH_IMAGE005
Direction coordinates and
Figure 591056DEST_PATH_IMAGE004
the coordinates of the direction are shown in the figure,
Figure DEST_PATH_IMAGE010
，
Figure DEST_PATH_IMAGE011
indicating the number of array elements.
4. The method according to claim 3, wherein in step S1.2, the phase shift of the sound source signal received by each array element is calculated as:
Figure DEST_PATH_IMAGE012
（2），
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE013
which is indicative of the frequency of the signal,
Figure DEST_PATH_IMAGE014
representing an imaginary operator.
5. The method for space-time domain joint detection of strong impact signals with enhanced beam focusing according to claim 4, wherein the array flow pattern matrix of each array element in step S1.3 is:
Figure DEST_PATH_IMAGE015
（3），
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE016
represent
Figure 855947DEST_PATH_IMAGE005
The discrete angle of the dimension(s) is,
Figure DEST_PATH_IMAGE017
to represent
Figure 313473DEST_PATH_IMAGE004
The discrete angle of the dimension(s) is,
Figure DEST_PATH_IMAGE018
，
Figure DEST_PATH_IMAGE019
，
Figure DEST_PATH_IMAGE020
to represent
Figure 737632DEST_PATH_IMAGE004
The number of the dimension grids is increased,
Figure DEST_PATH_IMAGE021
to represent
Figure 373144DEST_PATH_IMAGE005
And (5) the number of grids is maintained.
6. The method for space-time domain joint detection of strong impact signals with enhanced beam focusing of claim 5, wherein the step S2 comprises the steps of:
s2.1, based on an array flow pattern matrix, and obtaining spatial energy distribution through beam forming spatial scanning:
Figure DEST_PATH_IMAGE022
（4），
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE023
which indicates the lower limit of the processing band,
Figure DEST_PATH_IMAGE024
the upper limit of the processing band is shown,
Figure DEST_PATH_IMAGE025
is composed of
Figure DEST_PATH_IMAGE026
Performing Fourier transform on the received signals of the array elements to obtain frequency domain representation;
s2.2, determining the spatial position of the sound source signal based on the spatial energy distribution and by maximum scanning
Figure DEST_PATH_IMAGE027
。
7. The method for space-time domain joint detection of strong impact signals with enhanced beam focusing according to claim 6, wherein the step S3 comprises the steps of:
s3.1, pointing the microphone array to a spatial position
Figure 637248DEST_PATH_IMAGE027
To obtain a beam focusing signal, the calculation formula is:
Figure DEST_PATH_IMAGE028
（5）；
s3.2, performing inverse Fourier transform on the wave beam focusing signal to obtain an enhanced sound source signal of which the sound source signal is enhanced through a time-frequency domain, wherein the calculation formula is as follows:
Figure DEST_PATH_IMAGE029
（6）。
8. the method according to claim 7, wherein the method for detecting the strong impulse signal by space-time domain joint comprises,
in step S4.2, the one-dimensional probability density has the calculation formula:
Figure DEST_PATH_IMAGE030
（8），
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE031
which represents the ith sample point, is,
Figure DEST_PATH_IMAGE032
which is representative of the noise signal(s),
Figure DEST_PATH_IMAGE033
representing the noise power;
in step S4.3, the first joint probability density is calculated by the following formula:
Figure DEST_PATH_IMAGE034
（9），
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE035
representing a first joint probability density;
in step S4.4, the second joint probability density is calculated as:
Figure DEST_PATH_IMAGE036
（10），
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE037
a second combined probability density is represented that is,
Figure DEST_PATH_IMAGE038
which is indicative of a shock signal,
Figure DEST_PATH_IMAGE039
representing the shock signal power.
9. The method according to claim 8, wherein in step S4.5, the likelihood ratio function is:
Figure DEST_PATH_IMAGE040
（11）。
10. the strong impact signal space-time domain joint detection system based on any one of claims 1-9 is characterized by comprising a matrix construction module, a positioning module, a signal enhancement module and a judgment module which are connected in sequence;
the matrix construction module is used for calculating the time delay of each array element in the microphone array relative to the time delay of the sound source signal received by the array center so as to construct an array flow pattern matrix;
the positioning module is used for obtaining spatial energy distribution through beam forming spatial scanning based on the array flow pattern matrix so as to determine the position of a sound source signal;
the signal enhancement module is used for carrying out beam forming focusing on the basis of the sound source signal position and the microphone array so as to obtain an enhanced sound source signal of the sound source signal enhanced by the time-frequency domain;
and the judging module is used for calculating a likelihood ratio function based on the enhanced sound source signal by a maximum likelihood detection method, and judging whether the enhanced sound source signal has an impact signal according to the likelihood ratio function.
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