CN109884730B - Virtual array passive detection method based on deep-sea underwater glider platform - Google Patents
Virtual array passive detection method based on deep-sea underwater glider platform Download PDFInfo
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Abstract
The invention discloses a virtual array passive detection method based on a deep-sea underwater glider platform, and relates to an underwater acoustic line spectrum target passive detection method. The invention aims to solve the problem that the existing underwater glider platform cannot finish underwater long-distance detection with low signal-to-noise ratio. The process is as follows: 1: carrying a hydrophone, a compass system, a sound velocity gradiometer, a depth meter and a GPS system on an underwater glider platform; 2: obtaining an underwater motion track of the glider; 3: segmenting acoustic signals recorded by a hydrophone into virtual vertical array signals received corresponding to different depths; 4: judging whether a target exists or not according to the peak value output by the beam spectrum; if the virtual array beam spectrum output obtained in the step 4 has a single peak value, executing the step 5; if the virtual array beam spectrum output obtained in step 4 has a plurality of peak values, executing step 6; 5: obtaining a target line spectrum frequency; 6: and obtaining the multi-target line spectrum frequency. The invention is used in the field of underwater sound passive detection.
Description
Technical Field
The invention belongs to the field of underwater acoustic passive detection, and relates to a method for passively detecting an underwater acoustic line spectrum target.
Background
Due to environment particularity, the deep sea has strict requirements on a detection system platform for realizing passive detection of underwater acoustic targets and measurement of marine environment noise characteristics. The deep sea sound propagation has obvious sound convergence and shadow region effect, the detection performance of the system is greatly influenced by the working depth, and the detection system usually has the deep sea sound signal acquisition and recording capacity for a plurality of different depths so as to ensure that the detection equipment can favorably detect targets positioned at different distances. The deep sea underwater glider platform is a good carrier capable of meeting the requirements. The underwater glider has the characteristics of long underwater working time, long cruising distance, maneuvering depth and capability of position control and information return, and can play an important role in the field of underwater sound passive detection. The underwater acoustic line spectrum target detection device has the advantages that the underwater glider platform is used for carrying acoustic equipment to detect the underwater acoustic line spectrum target in the deep sea, the sensor carried by the underwater glider can acquire acoustic signal information of the underwater acoustic line spectrum target at different depths, and the influence of a shadow area can be avoided, so that the sound convergence phenomenon is reasonably utilized, and the detection capability is improved. Because the size and the electric power of the underwater glider are limited, large sonar equipment cannot be equipped, and only a small acoustic system can be carried, the detection capability obtained by the conventional detection processing method is very limited, effective space processing gain is difficult to obtain, and the underwater long-distance detection with low signal-to-noise ratio cannot be completed.
Disclosure of Invention
The invention aims to solve the problem that the existing underwater glider platform cannot finish underwater long-distance detection with low signal-to-noise ratio, and provides a virtual array passive detection method based on a deep-sea underwater glider platform.
A virtual array passive detection method based on a deep sea underwater glider platform is characterized by comprising the following steps: the method comprises the following specific processes:
step 1: the method comprises the following steps that a hydrophone, a compass system, a sound velocity gradiometer, a depth meter and a GPS system are carried on an underwater glider platform, the underwater glider platform performs glider maneuver in the horizontal and depth two-dimensional directions, and meanwhile, acoustic signals recorded by the hydrophone, compass postures recorded by the compass system, the depth of the underwater glider platform recorded by the depth meter and sound velocity parameter information recorded by the sound velocity gradiometer are collected and stored, and GPS position information on the water surface can be obtained when the glider goes out of the water;
step 2: calculating the underwater motion trail of the glider based on the compass attitude, the depth of the underwater glider platform, the sound velocity parameter information and the GPS position information obtained in the step 1 to obtain the underwater motion trail of the glider;
and step 3: segmenting acoustic signals recorded by a hydrophone into virtual vertical array signals received corresponding to different depths;
and 4, step 4: fitting the underwater motion trail of the glider obtained in the step (2) into a virtual vertical array type, performing virtual array beam forming processing on the virtual vertical array signal obtained in the step (3) to obtain virtual vertical array beam spectrum outputs with different virtual scanning quantities, and judging whether a target exists or not according to the peak value of the beam spectrum output;
if the virtual vertical array beam spectrum output obtained in the step 4 has a single peak value, executing a step 5;
if the virtual vertical array beam spectrum output obtained in the step 4 has a plurality of peak values, executing a step 6;
and 5: compensating the output peak position of the beam spectrum to obtain a virtual array beam output signal, performing spectrum analysis on the virtual array beam output signal, and measuring the frequency of a target line spectrum according to the result of the spectrum analysis to obtain the frequency of the target line spectrum;
step 6: and (4) if the virtual vertical array beam spectrum output obtained in the step (4) has a plurality of peak values, respectively compensating the position of each peak value to obtain a virtual array beam output signal, performing spectrum analysis on the virtual array beam output signal, and measuring the frequency of a target line spectrum according to the spectrum analysis result to obtain the multi-target line spectrum frequency.
The invention has the beneficial effects that:
the invention mainly provides a passive detection method of an underwater glider virtual array aiming at the problem of long-distance detection of a deep-sea underwater target.
The invention has the advantages that the small-scale acoustic system of single or multiple array elements carried on the underwater glider is used for receiving signals, and the virtual detection vertical aperture and the processing gain are obtained by reasonably dividing the virtual array of the signals, thereby realizing the effective detection of the long-distance low signal-to-noise ratio line spectrum target and providing a new method for the passive detection of the low-frequency target by the acoustic system based on the underwater glider platform. Compared with a large-scale vertical array, the system complexity and cost can be obviously reduced, the detection system based on the glider platform can carry out autonomous maneuvering and satellite communication, is more convenient to arrange, is convenient to adjust and control the working position of the system on the sea, has the advantage of maneuvering vertical depth, is favorable for selecting the detection depth, and can carry out necessary information return on the detection result.
The dual target results are shown in fig. 7, 8, 9. The specific simulation conditions are M60, T600, and Δ T10 s. The two target frequencies are 75Hz and 100Hz respectively, and the two target distances are 15km and 30km respectively. The virtual vertical array beam spectrum output simulation result is as shown in fig. 7, and as can be seen from the figure, the beam spectrum scanning result can have double peaks when there are double targets. Focusing on respective peak values according to the positions of the two peaks to obtain respective spectrum analysis results, wherein fig. 8 is a target 1 spectrum analysis result, and fig. 9 is a target 2 spectrum analysis result. According to the comparison of the two results, the 75Hz line spectrum in FIG. 8 is obviously higher than the 75Hz spectrum result in FIG. 9, so that the 75Hz line spectrum is judged to be the characteristic of the target 1, and the 100Hz rule is opposite to the characteristic, so that the 100Hz line spectrum is judged to be the frequency corresponding to the target 2.
Drawings
FIG. 1 is a diagram illustrating simulation of deep sea sound propagation characteristics;
FIG. 2 is a schematic cross-sectional view of the state of motion of an underwater glider;
FIG. 3 is a block flow diagram of an implementation of the present invention;
FIG. 4 is a side view showing the underwater motion state of the glider and the relative position of the moving object to be detected, R0、RkThe distance from the target to the glider;
FIG. 5 is a schematic diagram of a simulation of the virtual vertical array beam spectrum output of a single target detection case;
FIG. 6 is a schematic diagram of simulation of a spectrum result corresponding to a peak of a virtual array beam spectrum of a single-target detection case;
FIG. 7 is a schematic diagram of a simulation of the output of a multi-target detection case virtual vertical array beam spectrum;
FIG. 8 is a simulation diagram of a spectrum result corresponding to a spectrum peak 1 of a virtual array beam;
FIG. 9 is a schematic diagram of simulation of a spectrum result corresponding to a spectrum peak 2 of a virtual array beam;
FIG. 10 is a schematic view of an underwater glider platform carrier coordinate system;
FIG. 11 is a schematic view of the coordinate system of the water entry point of the underwater glider platform.
Detailed Description
The first embodiment is as follows: the method for passively detecting the virtual array based on the deep-sea underwater glider platform comprises the following specific processes:
the method comprises the steps of receiving acoustic signals based on a hydrophone carried on an underwater glider in the floating or sinking process, performing time frame division equivalent virtualization on the signals into a vertical array by utilizing the spatial position change of each frame of received signals, and performing space-time combined processing on the virtual vertical array signals to obtain signal processing gain, so that the remote detection of an underwater line spectrum target is realized.
As shown in fig. 1, the sound propagation in deep sea has obvious sound convergence region and sound shadow region effect, the detection of the glider is facilitated when the detection system is located in the convergence region, the detection of the target is not facilitated when the detection system is located in the shadow region, and the depths of the sound convergence regions of the targets at different distances are different, so that the detection system of the glider has a plurality of depth sound signal acquisition recording capabilities to ensure that the detection device can favorably detect the targets at different distances.
The schematic diagram of the detection working state of the glider is shown in fig. 2, the glider keeps the gliding movement state with a large inclination angle to move downwards during detection, and acoustic signals of different depth layers can be collected during working. The glider can carry a single hydrophone or a plurality of hydrophones which are positioned at different positions of the aircraft body to synchronously acquire and store the acoustic signals, and the glider platform simultaneously carries a depth meter and a compass to synchronously acquire and store depth and compass information. The aerodone acoustic detection system mainly comprises 5 parts, namely an acoustic data acquisition and storage system, a depth acquisition system, a compass data acquisition system, a detection signal processing system and a GPS system.
The specific detection method steps are shown in fig. 3.
Step 1: the method comprises the following steps that a hydrophone, a compass system, a sound velocity gradiometer, a depth meter and a GPS system are carried on an underwater glider platform, the underwater glider platform performs glider maneuver in the horizontal and depth two-dimensional directions, acoustic signals (sound wave signals, and total sound signals obtained by mixing sound signals generated by various sound sources in water) recorded by the hydrophone, the compass attitude recorded by the compass system, the depth of the underwater glider platform recorded by the depth meter, and the sound velocity (the sound wave propagation speed of the position where the glider is located) parameter information recorded by the sound velocity gradiometer are collected and stored, and the GPS position information on the water surface can be obtained when the glider goes out of water;
the compass system model is TCM3 electronic compass of the United states PNI company;
step 2: calculating the underwater motion trail of the glider based on the compass attitude, the depth of the underwater glider platform, the sound velocity parameter information and the GPS position information obtained in the step 1 to obtain the underwater motion trail of the glider;
and step 3: segmenting acoustic signals recorded by a hydrophone into virtual vertical array signals received corresponding to different depths;
and 4, step 4: fitting the underwater motion trail of the glider obtained in the step (2) into a virtual vertical array type, performing virtual array beam forming processing on the virtual vertical array signal obtained in the step (3) to obtain virtual vertical array beam spectrum output with different virtual scanning quantities (a set scanning variable with time delay or phase shift), and judging whether a target exists or not according to the peak value of the beam spectrum output;
if the virtual vertical array beam spectrum output obtained in the step 4 has a single peak value, executing a step 5;
if the virtual vertical array beam spectrum output obtained in the step 4 has a plurality of peak values, executing a step 6;
and 5: compensating the output peak position of the beam spectrum to obtain a virtual array beam output signal, performing spectrum analysis on the virtual array beam output signal, and measuring the frequency of a target line spectrum according to the result of the spectrum analysis to obtain the frequency of the target line spectrum;
step 6: if the virtual vertical array beam spectrum output obtained in the step 4 has a plurality of peak values, judging the number of the multiple targets according to the number of the peak values; the specific process is as follows:
and roughly judging the number of the targets according to the number of the peaks when the multiple peaks occur, for example, roughly judging the double targets when the double peaks occur.
And respectively compensating each peak value position to obtain a virtual array wave beam output signal, performing spectrum analysis on the virtual array wave beam output signal, and measuring the frequency of a target line spectrum according to the spectrum analysis result to obtain the frequency of the multi-target line spectrum.
The second embodiment is as follows: the difference between the embodiment and the specific embodiment is that, in the step 2, the underwater motion track of the glider is calculated based on the compass attitude, the depth of the underwater glider platform, the sound velocity parameter information and the GPS position information obtained in the step 1, so as to obtain the underwater motion track of the glider; the specific process is as follows:
step 21, obtaining the average ocean current velocity and flow direction information of a moving area where the glider is located according to the GPS position information of the water inlet point and the water outlet point of the glider;
step 22, calculating the vertical movement speed of the glider according to a depth meter carried by the glider;
step 23, acquiring the posture of the glider at each moment by using the compass posture recorded by the compass system carried by the glider, so as to acquire a posture transfer matrix at each moment;
and 24, calculating to obtain the underwater motion track of the glider by using a navigation positioning coordinate conversion formula based on the steps 21, 22 and 23.
Other steps and parameters are the same as those in the first embodiment.
The third concrete implementation mode: the difference between the present embodiment and the first or second embodiment is that, in the step 21, the average ocean current velocity and the flow direction information of the motion area where the glider is located are obtained according to the GPS position information of the water inlet point and the water outlet point of the glider; the specific process is as follows:
assuming that the GPS coordinates of the water inlet point and the water outlet point are Gr＝(Xr,Yr) And Gc＝(Xc,Yc)，
Wherein, Xr,XcIs longitude, Yr,YcIs latitude;
the earth is regarded as a standard sphere, and the distance is obtained by solving the arc length between the water inlet point and the water outlet point; converting latitude and longitude into radian:
Y′r＝Yr*π/180
X′r＝Xr*π/180
Y′c＝Yc*π/180
X′c＝Xc*π/180
wherein, Y'rIs arc length, X 'converted from latitude of water entry point'rIs arc length, Y 'converted from the longitude of the point of entry'cIs arc length, X 'converted from water outlet point latitude'cIs the arc length converted from the water outlet point longitude; denotes a multiplication number;
then, the north-south distance between the two points is dY＝RG*|(Y′r-Y′c) L, east-west distance is dX＝RG*|(X′r-X′c)|；
Wherein R isGRepresenting the radius of the earth, RG＝6371.0km；
The time for the glider to float downwards to form a section is T, and the average ocean current velocity V of the south-north direction and the east-west direction of the moving area where the glider is located is obtainedY＝dY/T，VX＝dX/T；
It is assumed that the average current velocity is constant during one submergence and ascent of the glider.
Other steps and parameters are the same as those in the first or second embodiment.
The fourth concrete implementation mode: the present embodiment is different from the first to third embodiments in that the vertical movement speed of the glider is calculated in step 22 based on a depth gauge mounted on the glider; the specific process is as follows:
depth information (depth information) of underwater glider platform recorded at current time of gliderIs the result of the depth gauge) is derived over time to obtain the vertical movement velocity V of the glider at the time tZ(t)；
Setting the depth information of the underwater glider platform measured at the time t as h (t), and then setting the vertical motion speed V of the gliderZThe formula for calculation of (t) is:
VZ(t)＝dh(t)/dt
where d represents the derivative.
Other steps and parameters are the same as those in one of the first to third embodiments.
The fifth concrete implementation mode: the present embodiment is different from the first to the fourth embodiments in that, in the step 23, the posture of the glider at each time is obtained by using the compass posture recorded by the compass system carried by the glider, so as to obtain the posture transition matrix at each time; the specific process is as follows:
setting the posture transfer matrix at the time t as R (t); the platform carrier coordinate system is established according to the rule as shown in fig. 10: the advancing direction of the underwater glider platform is taken as the positive direction of an X 'axis, the extending direction of the wings which is vertical to the X' axis is taken as a Y 'axis, and a Z' axis is the direction which is vertical to the X 'oY' plane under the condition of adopting a right-hand coordinate system;
according to the installation mode of the compass, the anticlockwise rotation angle along the X' axis of the underwater glider platform is used as a roll angle r (t), and the included angle between the deviation of the axis of the underwater glider platform to the seabed and the horizontal direction is used as a pitch angle
Namely the angle of clockwise rotation of the underwater glider platform along the Y' axis; taking an included angle between the east-off direction and the true north direction of the underwater glider platform when the underwater glider platform travels as a course angle theta (t);
the attitude transfer matrix calculation formula is as follows:
wherein R (t) is a posture transition matrix.
Other steps and parameters are the same as in one of the first to fourth embodiments.
The sixth specific implementation mode: the difference between the present embodiment and one of the first to fifth embodiments is that, in the step 24, the underwater motion trajectory of the glider is calculated by using a navigation and positioning coordinate conversion formula; the specific process is as follows:
obtaining the instantaneous speed of the glider at the t-th moment under the action of gravity and buoyancy according to the vertical movement speed of the glider and the posture transfer matrix at each moment;
let the velocity vector of the glider platform relative to the glider platform carrier coordinate system be
That is, assuming that the glider slides forward along the underwater glider platform carrier coordinate system, only the velocity vector of the glider platform along the X 'axis direction is V'xThe value of (t) is of practical significance, and the speeds of the other two directions are 0; v'x(t) the value of which may be determined by the vertical movement velocity V obtained in step 22Z(t) obtaining the calculation formula as follows:
V′x(t)＝-Vz(t)/sinr(t)cosθ(t)
wherein, VZ(t) is the vertical movement speed of the underwater glider platform under the geodetic coordinate system,
is the velocity vector, V ', of the glider platform relative to the glider body coordinate system'x(t) is a velocity vector, V ', of the glider platform along the X ' axis 'y(t) is a velocity vector, V ', of the glider platform along the Y ' axis 'z(t) is the velocity vector of the glider platform along the Z' axis direction;
underwater glider platform instantaneous velocity vector without considering ocean current influence under earth coordinate system
Velocity vector with carrier coordinate system
Has a conversion relation of
Wherein, VE(t) instantaneous east speed, V, of underwater glider platform without consideration of ocean current influence at time t in geodetic coordinate systemN(t) the instantaneous north speed of the underwater glider platform without considering the influence of ocean currents under the geodetic coordinate system at the moment t;
the total velocity of the glider in the geodetic coordinate system is expressed as
The calculation formula for obtaining the total speed of the glider according to the ocean current flow velocity and the instantaneous velocity vector is as follows:
wherein v isE(t) is the east instantaneous velocity of the underwater glider under the geodetic coordinates at time t, vN(t) is the north instantaneous velocity of the underwater glider under the geodetic coordinates at time t, vH(t) is the vertical instantaneous speed of the underwater glider under the geodetic coordinates at the moment t;
as shown in FIG. 11, the total velocity of the glider in the geodetic coordinate system is determined based on the GPS position information of the water entry point
The instantaneous value of the time point is integrated to obtain three-dimensional coordinate information of the glider at each moment, and the coordinate combination at each moment is the glider motion track of a complete section; the coordinate output calculation formula of the time t relative to the water inlet point is as follows:
wherein X (t) is an x-axis coordinate value obtained by establishing a coordinate system under the condition that the underwater glider platform takes the water inlet point as the origin, Y (t) is a y-axis coordinate value obtained by establishing the coordinate system under the condition that the underwater glider platform takes the water inlet point as the origin, Z (t) is a z-axis coordinate value obtained by establishing the coordinate system under the condition that the underwater glider platform takes the water inlet point as the origin, t (t) is a z-axis coordinate value obtained by establishing the coordinate system under the condition that the underwater glider platform takes the wateri-1Synchronously acquiring the values of the last compass and depth meter at the moment tiIs the current time.
Other steps and parameters are the same as those in one of the first to fifth embodiments.
The seventh embodiment: the difference between this embodiment and one of the first to sixth embodiments is that, in step 3, the acoustic signals recorded by the hydrophones are segmented and divided into virtual vertical array signals received corresponding to different depths; the specific process is as follows:
the method comprises the steps of dividing acoustic signal data recorded by a hydrophone into different sections according to a time equal division relation, wherein the number of the sections is equal to that of virtual vertical array elements, namely, assuming that M elements are required to be virtualized, dividing the acoustic signal recorded by the hydrophone into M sections, wherein the time length of each section of data is equal, and each section of data represents a received signal of one virtual vertical array element.
Other steps and parameters are the same as those in one of the first to sixth embodiments.
The specific implementation mode is eight: the embodiment is different from the first to seventh embodiments in that, in the step 4, the underwater motion trajectory of the glider obtained in the step 2 is fitted into a virtual vertical array type, the virtual vertical array signal obtained in the step 3 is subjected to virtual array beam forming processing to obtain virtual vertical array beam spectrum outputs with different virtual scanning amounts (a set scanning variable with time delay or phase shift), and whether a target exists or not is judged according to a peak value of the beam spectrum output;
if the virtual vertical array beam spectrum output obtained in the step 4 has a single peak value, executing a step 5;
if the virtual vertical array beam spectrum output obtained in the step 4 has a plurality of peak values, executing a step 6;
the specific process is as follows:
obtaining a virtual vertical matrix array type of a corresponding position according to the underwater motion track of the glider obtained in the step 2 and a time relation (track calculation is carried out in the step 2 so as to obtain the motion track of the glider, and the corresponding track shape in a data processing time period is the array type of the virtual vertical matrix); performing beam scanning on the line spectrum target according to the virtual vertical array type, compensating the time delay or the phase of the virtual vertical array signal obtained in the step 3 through the beam scanning (the beam forming can be a time domain or a frequency domain, the time domain compensation is a time delay, the frequency domain compensation is a phase, the two methods are mutually equivalent), when the virtual scanning amount changes, the output energy of the virtual vertical array beam spectrum obtained through compensation is different, and when the time delay or the phase shift corresponding to the virtual scanning amount is consistent with the time delay or the phase shift of the line spectrum target propagating to the position of the virtual vertical array type (the virtual vertical array type at the corresponding position obtained in the step 2), the virtual vertical array signal (the virtual vertical array signal obtained in the step 3) can form in-phase superposition, so that the beam spectrum output forms a peak value; after the preset virtual scanning amount is scanned, judging whether a target exists or not according to the peak value output by the beam spectrum obtained by scanning, and if an obvious peak value exists, indicating that the target exists;
if the virtual vertical array beam spectrum output obtained in the step 4 has a single peak value, executing a step 5;
if the virtual vertical array beam spectrum output obtained in the step 4 has a plurality of peak values, executing a step 6;
the number of the plurality is more than or equal to 2;
(the virtual scan is a scan variable of time delay or phase shift. since it is unknown what this value is, a variable is set, the result of the calculation changes as the variable changes, and a peak appears just after the scan is consistent with the actual value, by which the detection of the presence or absence of the object is achieved.)
Other steps and parameters are the same as those in one of the first to seventh embodiments.
The specific implementation method nine: the difference between this embodiment and the first to eighth embodiment is that, in step 5, the beam spectrum output peak position is compensated to obtain a virtual array beam output signal, the virtual array beam output signal is subjected to spectrum analysis, and a target line spectrum is subjected to frequency measurement according to a spectrum analysis result to obtain a target line spectrum frequency; the specific process is as follows:
compensating a virtual compensation quantity value corresponding to the output peak position of the beam spectrum to obtain a beam output signal (beam forming is to add all array element data after time delay or phase shift compensation to obtain a path of signal which is the beam output signal), performing Fourier transform on the beam output signal to obtain a frequency spectrum analysis result, measuring the frequency of a target line spectrum according to the frequency spectrum analysis result, wherein the frequency corresponding to the peak value in the frequency spectrum is the target line spectrum frequency result;
other steps and parameters are the same as those in one to eight of the embodiments.
The detailed implementation mode is ten: the difference between this embodiment and the first to ninth embodiments is that, in step 6, if the virtual vertical array beam spectrum output obtained in step 4 has a plurality of peaks, the position of each peak is compensated to obtain a virtual array beam output signal, the virtual array beam output signal is subjected to spectrum analysis, and a target line spectrum is subjected to frequency measurement according to a spectrum analysis result to obtain a multi-target line spectrum frequency; the specific process is as follows:
step 61: compensating the virtual compensation quantity value corresponding to each peak value position to obtain a beam output signal corresponding to peak value compensation; (beam forming is to add all array element data after time delay or phase shift compensation to obtain a path of signal, which is a beam output signal.)
Step 62: carrying out Fourier transform on the wave beam output signal compensated by each peak value to obtain a spectrum analysis result of a plurality of peak value rough judgment targets;
and step 63: measuring the frequency of a target line spectrum according to the result of the frequency spectrum analysis; in the frequency measurement process, multiple targets with the same frequency may exist, and targets with different frequencies may also exist.
If the frequency measurement results of the multiple peak values are the same line spectrum frequency, the same frequency multiple targets are obtained, and the number of the targets and the line spectrum frequency value corresponding to the targets are given; the number of the targets is the number of peak values;
if the frequency measurement results of the multiple peak values respectively correspond to different line spectrum frequencies, judging the multiple targets with different frequencies, and giving the number of the targets and the line spectrum frequency value corresponding to each target; the number of the targets is the number of peak values;
the number of the plurality is 2 or more.
Other steps and parameters are the same as those in one of the first to ninth embodiments.
The following examples were used to demonstrate the beneficial effects of the present invention:
the first embodiment is as follows:
the preparation method comprises the following steps:
the invention is further described below with reference to the accompanying drawings.
Example 1:
the moving states of the single-frequency line spectrum target, the underwater glider and the target are shown in figure 4. Processing according to a predetermined detection step:
the underwater glider platform performs glider maneuvering in the horizontal and depth two-dimensional directions, and simultaneously collects and stores acoustic signals, compass postures, depths and sound velocity parameter information; calculating the underwater motion track of the glider to obtain the motion track of the underwater glider; dividing signals with the length of T received by a hydrophone into M sections, wherein each section is delta T long, and obtaining M-element virtual array signals; fitting the obtained motion trail of the underwater glider into a virtual vertical array type, carrying out virtual array beam forming processing on virtual vertical array signals, carrying out beam scanning compensation on M-element virtual array signals to obtain virtual vertical array beam spectrum outputs with different virtual scanning quantities, and judging whether a target exists or not according to the peak value of the beam spectrum output; and compensating the output peak position of the beam spectrum to obtain a virtual array beam output signal, performing spectrum analysis on the virtual array beam output signal, and measuring the frequency of a target line spectrum according to the result of the spectrum analysis to obtain the frequency of the target line spectrum.
The simulation result of the virtual vertical array beam spectrum output obtained by beam scanning is shown in fig. 5. The specific simulation conditions assume that the target is a single target with a long distance of 30km, M is 60, T is 600s, Δ T is 10s, and the single target frequency is 100 Hz. It can be seen that the beam spectrum scanning result has a distinct peak when a single target exists. The output peak position is compensated to obtain a virtual array wave beam output signal, the virtual array wave beam output signal is subjected to spectrum analysis, the result is shown in fig. 6, the line spectrum frequency information of the target can be obtained from fig. 6, the maximum value normalization comparison is carried out on the frequency spectrum of the single-element input signal and the frequency spectrum output after the virtual array wave beam is formed in fig. 6, the fact that the frequency spectrum noise background of the single-element input signal is obviously higher than the result after the wave beam is formed can be seen, and the fact that the virtual array processing can bring obvious signal-to-noise ratio gain can be verified.
Example 2:
two non-co-frequency line spectrum targets are arranged, the motion situations of the underwater glider and the targets are the same as that of a single target, and the distances between the two targets are different. Also, the processing is performed according to a predetermined detection procedure:
the underwater glider platform performs glider maneuvering in the horizontal and depth two-dimensional directions, and simultaneously collects and stores acoustic signals, compass postures, depths and sound velocity parameter information; calculating the underwater motion track of the glider to obtain the motion track of the underwater glider; dividing signals with the length of T received by a hydrophone into M sections, wherein each section is delta T long, and obtaining M-element virtual array signals; fitting the obtained motion trail of the underwater glider into a virtual vertical array type, carrying out virtual array beam forming processing on virtual vertical array signals, carrying out beam scanning compensation on M-element virtual array signals to obtain virtual vertical array beam spectrum outputs with different virtual scanning quantities, and judging whether a target exists or not according to the peak value of the beam spectrum output; and compensating the output peak position of the beam spectrum to obtain a virtual array beam output signal, performing spectrum analysis on the virtual array beam output signal, and measuring the frequency of a target line spectrum according to the result of the spectrum analysis to obtain the frequency of the target line spectrum.
The dual target results are shown in fig. 7, 8, 9. The specific simulation conditions are M60, T600, and Δ T10 s. The two target frequencies are 75Hz and 100Hz respectively, and the two target distances are 15km and 30km respectively. The virtual vertical array beam spectrum output simulation result is as shown in fig. 7, and as can be seen from the figure, the beam spectrum scanning result can have double peaks when there are double targets. Focusing on respective peak values according to the positions of the two peaks to obtain respective spectrum analysis results, wherein fig. 8 is a target 1 spectrum analysis result, and fig. 9 is a target 2 spectrum analysis result. According to the comparison of the two results, the 75Hz line spectrum in FIG. 8 is obviously higher than the 75Hz spectrum result in FIG. 9, so that the 75Hz line spectrum is judged to be the characteristic of the target 1, and the 100Hz rule is opposite to the characteristic, so that the 100Hz line spectrum is judged to be the frequency corresponding to the target 2.
The present invention is capable of other embodiments and its several details are capable of modifications in various obvious respects, all without departing from the spirit and scope of the present invention.
Claims (10)
1. A virtual array passive detection method based on a deep sea underwater glider platform is characterized by comprising the following steps: the method comprises the following specific processes:
step 1: the method comprises the following steps that a hydrophone, a compass system, a sound velocity gradiometer, a depth meter and a GPS system are carried on an underwater glider platform, the underwater glider platform performs glider maneuver in the horizontal and depth two-dimensional directions, and meanwhile, acoustic signals recorded by the hydrophone, compass postures recorded by the compass system, the depth of the underwater glider platform recorded by the depth meter and sound velocity parameter information recorded by the sound velocity gradiometer are collected and stored, and GPS position information on the water surface can be obtained when the glider goes out of the water;
step 2: calculating the underwater motion trail of the glider based on the compass attitude, the depth of the underwater glider platform, the sound velocity parameter information and the GPS position information obtained in the step 1 to obtain the underwater motion trail of the glider;
and step 3: segmenting acoustic signals recorded by a hydrophone into virtual vertical array signals received corresponding to different depths;
and 4, step 4: fitting the underwater motion trail of the glider obtained in the step (2) into a virtual vertical array type, performing virtual array beam forming processing on the virtual vertical array signal obtained in the step (3) to obtain virtual vertical array beam spectrum outputs with different virtual scanning quantities, and judging whether a target exists or not according to the peak value of the beam spectrum output;
if the virtual vertical array beam spectrum output obtained in the step 4 has a single peak value, executing a step 5;
if the virtual vertical array beam spectrum output obtained in the step 4 has a plurality of peak values, executing a step 6;
and 5: compensating the output peak position of the beam spectrum to obtain a virtual array beam output signal, performing spectrum analysis on the virtual array beam output signal, and measuring the frequency of a target line spectrum according to the result of the spectrum analysis to obtain the frequency of the target line spectrum;
step 6: and (4) if the virtual vertical array beam spectrum output obtained in the step (4) has a plurality of peak values, respectively compensating the position of each peak value to obtain a virtual array beam output signal, performing spectrum analysis on the virtual array beam output signal, and measuring the frequency of a target line spectrum according to the spectrum analysis result to obtain the multi-target line spectrum frequency.
2. The method for passively detecting the virtual array based on the deep-sea underwater glider platform is characterized in that: in the step 2, calculating the underwater motion trail of the glider based on the compass attitude, the depth of the underwater glider platform, the sound velocity parameter information and the GPS position information obtained in the step 1 to obtain the underwater motion trail of the glider; the specific process is as follows:
step 21, obtaining the average ocean current velocity and flow direction information of a moving area where the glider is located according to the GPS position information of the water inlet point and the water outlet point of the glider;
step 22, calculating the vertical movement speed of the glider according to a depth meter carried by the glider;
step 23, acquiring the posture of the glider at each moment by using the compass posture recorded by the compass system carried by the glider, so as to acquire a posture transfer matrix at each moment;
and 24, calculating to obtain the underwater motion track of the glider by using a navigation positioning coordinate conversion formula based on the steps 21, 22 and 23.
3. The deep sea underwater glider platform-based virtual array passive detection method according to claim 2, characterized in that: in the step 21, the average ocean current velocity and flow direction information of the moving area where the glider is located are obtained according to the GPS position information of the water inlet point and the water outlet point of the glider; the specific process is as follows:
assuming that the GPS coordinates of the water inlet point and the water outlet point are Gr＝(Xr,Yr) And Gc＝(Xc,Yc)，
Wherein, Xr,XcIs longitude, Yr,YcIs latitude;
obtaining a distance by solving the arc length between the water inlet point and the water outlet point; converting latitude and longitude into radian:
Y′r＝Yr*π/180
X′r＝Xr*π/180
Y′c＝Yc*π/180
X′c＝Xc*π/180
wherein, Y'rIs arc length, X 'converted from latitude of water entry point'rIs arc length, Y 'converted from the longitude of the point of entry'cIs arc length, X 'converted from water outlet point latitude'cIs the arc length converted from the water outlet point longitude; denotes a multiplication number;
then, the north-south distance between the two points is dY＝RG*|(Y′r-Y′c) L, east-west distance is dX＝RG*|(X′r-X′c)|；
Wherein R isGRepresenting the radius of the earth, RG＝6371.0km；
The time for the glider to float downwards to form a section is T, and the average ocean current velocity V of the south-north direction and the east-west direction of the moving area where the glider is located is obtainedY＝dY/T，VX＝dX/T。
4. The deep sea underwater glider platform-based virtual array passive detection method according to claim 3, characterized in that: in the step 22, the vertical movement speed of the glider is calculated according to the depth gauge carried by the glider; the specific process is as follows:
the depth information of the underwater glider platform recorded at the current moment of the glider is derived from the time to obtain the vertical movement speed V of the glider at the t momentZ(t)；
Setting the depth information of the underwater glider platform measured at the time t as h (t), and then setting the vertical motion speed V of the gliderZThe formula for calculation of (t) is:
VZ(t)＝dh(t)/dt
where d represents the derivative.
5. The method for passively detecting the virtual array based on the deep sea underwater glider platform is characterized in that: in the step 23, the posture of the glider at each moment is obtained by using the compass posture recorded by the compass system carried by the glider, so that a posture transition matrix at each moment is obtained; the specific process is as follows:
setting the posture transfer matrix at the time t as R (t); the advancing direction of the underwater glider platform is taken as the positive direction of an X 'axis, the extending direction of the wings which is vertical to the X' axis is taken as a Y 'axis, and a Z' axis is the direction which is vertical to the X 'oY' plane under the condition of adopting a right-hand coordinate system;
according to the installation mode of the compass, the anticlockwise rotation angle along the X' axis of the underwater glider platform is used as a roll angle r (t), and the included angle between the deviation of the axis of the underwater glider platform to the seabed and the horizontal direction is used as a pitch angle
Namely the angle of clockwise rotation of the underwater glider platform along the Y' axis; taking an included angle between the east-off direction and the true north direction of the underwater glider platform when the underwater glider platform travels as a course angle theta (t);
the attitude transfer matrix calculation formula is as follows:
wherein R (t) is a posture transition matrix.
6. The deep sea underwater glider platform-based virtual array passive detection method according to claim 5, characterized in that: in the step 24, a navigation positioning coordinate conversion formula is used for calculating to obtain the underwater motion track of the glider; the specific process is as follows:
obtaining the instantaneous speed of the glider at the t-th moment under the action of gravity and buoyancy according to the vertical movement speed of the glider and the posture transfer matrix at each moment;
let the velocity vector of the glider platform relative to the glider platform carrier coordinate system be
That is, assuming that the glider slides forward along the underwater glider platform carrier coordinate system, the velocity vector of the glider platform along the X 'axis direction is V'x(t), the other two directional velocities are 0; v'x(t) value is the vertical movement velocity V obtained in step 22Z(t) obtaining the calculation formula as follows:
V′x(t)＝-Vz(t)/sinr(t)cosθ(t)
wherein, VZ(t) is the vertical movement speed of the underwater glider platform under the geodetic coordinate system,
is the velocity vector, V ', of the glider platform relative to the glider body coordinate system'x(t) is a velocity vector, V ', of the glider platform along the X ' axis 'y(t) is a velocity vector, V ', of the glider platform along the Y ' axis 'z(t) is the velocity vector of the glider platform along the Z' axis direction;
underwater glider platform instantaneous velocity vector without considering ocean current influence under earth coordinate system
Velocity vector with carrier coordinate system
Has a conversion relation of
Wherein, VE(t) instantaneous east speed, V, of underwater glider platform without consideration of ocean current influence at time t in geodetic coordinate systemN(t) the instantaneous north speed of the underwater glider platform without considering the influence of ocean currents under the geodetic coordinate system at the moment t;
the total velocity of the glider in the geodetic coordinate system is expressed as
The calculation formula for obtaining the total speed of the glider in the geodetic coordinate system according to the ocean current flow velocity and the instantaneous velocity vector is as follows:
wherein v isE(t) is the east instantaneous velocity of the underwater glider under the geodetic coordinates at time t, vN(t) is the north instantaneous velocity of the underwater glider under the geodetic coordinates at time t, vH(t) is the vertical instantaneous speed of the underwater glider under the geodetic coordinates at the moment t;
using GPS position information of water inlet point as reference, and measuring total speed of glider in geodetic coordinate system
The instantaneous value of the time point is integrated to obtain three-dimensional coordinate information of the glider at each moment, and the coordinate combination at each moment is the glider motion track of a complete section; the coordinate output calculation formula of the time t relative to the water inlet point is as follows:
wherein X (t) is an x-axis coordinate value obtained by establishing a coordinate system under the condition that the underwater glider platform takes the water inlet point as the origin, Y (t) is a y-axis coordinate value obtained by establishing the coordinate system under the condition that the underwater glider platform takes the water inlet point as the origin, Z (t) is a z-axis coordinate value obtained by establishing the coordinate system under the condition that the underwater glider platform takes the water inlet point as the origin, t (t) is a z-axis coordinate value obtained by establishing the coordinate system under the condition that the underwater glider platform takes the wateri-1Synchronously acquiring the values of the last compass and depth meter at the moment tiIs the current time.
7. The method for passively detecting the virtual array based on the deep sea underwater glider platform is characterized in that: in the step 3, the acoustic signals recorded by the hydrophones are segmented and divided into virtual vertical array signals received corresponding to different depths; the specific process is as follows:
acoustic signal data recorded by the hydrophone are divided into different sections according to a time equal division relation, the number of the sections is equal to that of the virtual vertical array elements, the time length of each section of data is equal, and each section of data represents a received signal of one virtual vertical array element.
8. The method for passively detecting the virtual array based on the deep sea underwater glider platform is characterized in that: step 4, the underwater motion trail of the glider obtained in step 2 is fitted into a virtual vertical array type, the virtual vertical array signal obtained in step 3 is subjected to virtual array beam forming processing to obtain virtual vertical array beam spectrum outputs with different virtual scanning quantities, and whether a target exists or not is judged according to the peak value of the beam spectrum output;
if the virtual vertical array beam spectrum output obtained in the step 4 has a single peak value, executing a step 5;
if the virtual vertical array beam spectrum output obtained in the step 4 has a plurality of peak values, executing a step 6;
the specific process is as follows:
obtaining a virtual vertical array type of a corresponding position according to the underwater motion trail of the glider obtained in the step 2 and a time relation; performing beam scanning on the line spectrum target according to the virtual vertical array type, compensating the time delay or the phase of the virtual vertical array signal obtained in the step 3 through the beam scanning, wherein the virtual vertical array beam spectrum output energy obtained through the compensation is different when the virtual scanning amount changes, and when the time delay or the phase shift corresponding to the virtual scanning amount is consistent with the time delay or the phase shift of the line spectrum target spreading to the position of the virtual vertical array type, the virtual vertical array signal forms in-phase superposition, so that the beam spectrum output forms a peak value; after the preset virtual scanning amount is scanned, judging whether a target exists or not according to the peak value output by the beam spectrum obtained by scanning, wherein the existence of the peak value indicates that the target exists;
if the virtual vertical array beam spectrum output obtained in the step 4 has a single peak value, executing a step 5;
if the virtual vertical array beam spectrum output obtained in the step 4 has a plurality of peak values, executing a step 6;
the number of the plurality is 2 or more.
9. The method for passively detecting the virtual array based on the deep sea underwater glider platform is characterized in that: in the step 5, the output peak position of the beam spectrum is compensated to obtain a virtual array beam output signal, the virtual array beam output signal is subjected to spectrum analysis, and the target line spectrum is subjected to frequency measurement according to the spectrum analysis result to obtain the target line spectrum frequency; the specific process is as follows:
and compensating the virtual compensation quantity value corresponding to the position of the output peak value of the beam spectrum to obtain a beam output signal, performing Fourier transform on the beam output signal to obtain a spectrum analysis result, measuring the frequency of the target line spectrum according to the spectrum analysis result, wherein the frequency corresponding to the peak value in the spectrum is the target line spectrum frequency result.
10. The method for passively detecting the virtual array based on the deep sea underwater glider platform is characterized in that: in the step 6, if the virtual vertical array beam spectrum output obtained in the step 4 has a plurality of peaks, the position of each peak is compensated to obtain a virtual array beam output signal, the virtual array beam output signal is subjected to spectrum analysis, and a target line spectrum is subjected to frequency measurement according to a spectrum analysis result to obtain a multi-target line spectrum frequency; the specific process is as follows:
step 61: compensating the virtual compensation quantity value corresponding to each peak value position to obtain a beam output signal corresponding to peak value compensation;
step 62: carrying out Fourier transform on the wave beam output signal compensated by each peak value to obtain a spectrum analysis result of a plurality of peak value rough judgment targets;
and step 63: measuring the frequency of a target line spectrum according to the result of the frequency spectrum analysis;
if the frequency measurement results of the multiple peak values are the same line spectrum frequency, the same frequency multiple targets are obtained, and the number of the targets and the line spectrum frequency value corresponding to the targets are given; the number of the targets is the number of peak values;
if the frequency measurement results of the multiple peak values respectively correspond to different line spectrum frequencies, judging the multiple targets with different frequencies, and giving the number of the targets and the line spectrum frequency value corresponding to each target; the number of the targets is the number of peak values;
the number of the plurality is 2 or more.
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