FORWARD ACOUSTIC SCATTERING BASED DOUBLE-TRANSMITTER AND DOUBLE-RECEIVER NETWORKING TARGET DETECTION SYSTEM AND METHOD THEREOF

Abstract

The present invention relates to a forward acoustic scattering based double-transmitter and double-receiver networking target detection system and method thereof. Two transmitting ends and two receiving ends are adopted, anchored at a sea bottom, and arranged in a parallelogram layout. Time of a target crossing transmitting-receiving connection lines is extracted by adopting a proper direct wave suppression method; and unknown parameters of the horizontal distance, the target velocity and the included angle between the target track and the transmitting-receiving connection lines are estimated at corresponding moving time intervals when the target crosses the four transmitting-receiving connection lines according to different crossing modes. An arrangement mode is simple and flexible, and monitoring of sea areas and sea channels can be realized. The information of the time of the target crossing the transmitting-receiving connection lines, extracted by the method, is more accurate and reliable.

Claims

1. A forward acoustic scattering based double-transmitter and double-receiver networking target detection system, comprising: two transmitting ends and two receiving ends; wherein the two transmitting ends and the two receiving ends are anchored at a sea bottom, and formed in a parallelogram layout; the two transmitting ends are respectively marked as T.sub.x1 and T.sub.x2; the two receiving ends are respectively marked as R.sub.x1 and R.sub.x2; T.sub.x1-R.sub.x1, R.sub.x1-R.sub.x2, R.sub.x2-T.sub.x2 and T.sub.x2-T.sub.x1 form four edges of the parallelogram; T.sub.x1-R.sub.x2 and T.sub.x2-R.sub.x1 are two diagonal lines of the parallelogram; a length of T.sub.x1-R.sub.x1 is marked as l; a length of R.sub.x1-R.sub.x2 is marked as h; an included angle between T.sub.x1-T.sub.x2 and T.sub.x2-R.sub.x2 is marked as ; and four transmitting-receiving connection lines are formed: T.sub.x1-R.sub.x1, T.sub.x1-R.sub.x2, T.sub.x2-R.sub.x1 and T.sub.x2-R.sub.x2; and depths of the transmitting ends and the receiving ends are equal.

2. The forward acoustic scattering based double-transmitter and double-receiver networking target detection system according to claim 1, wherein when the number of transmitting sound sources of the transmitting ends is in a range of 2-50, and the number of receiving hydrophone arrays is in a range of 2-50; a multi-transmitter multi-receiver forward detection system is formed.

3. The forward acoustic scattering based double-transmitter and double-receiver networking target detection system according to claim 1, wherein a spacing of the transmitting sound sources is 10-10000 meters.

4. The forward acoustic scattering based double-transmitter and double-receiver networking target detection system according to claim 1, wherein a spacing of the receiving hydrophone arrays is 10-10000 meters.

5. A method for detection by using the forward acoustic scattering based double-transmitter and double-receiver networking target detection system according to claim 1, comprising the following steps of estimating unknown parameters of d, v and when a target successively crosses T.sub.x1-R.sub.x1, T.sub.x2-R.sub.x1, T.sub.x1-R.sub.x2 and T.sub.x2-R.sub.x2 at uniform velocity v along a straight line, with a horizontal distance from a crossing point of the target on the transmitting-receiving connection line T.sub.x1-R.sub.x1 to R.sub.x1 marked as d and an included angle between a target track and the transmitting-receiving connection line T.sub.x1-R.sub.x1 marked as : step 1: extracting time of the target crossing transmitting-receiving connection lines by adopting a direct wave suppression method, wherein since four transmitting-receiving connection lines exist under a double-transmitter and double-receiver configuration, four time are successively marked as t.sub.1, t.sub.2, t.sub.3 and t.sub.4 according to a time sequence; step 2: calculating corresponding moving time intervals when the target crosses the four transmitting-receiving connection lines as t.sub.21=t.sub.2.sub.1, t.sub.32=t.sub.3t.sub.2 and t.sub.43=t.sub.4t.sub.3; step 3: substituting parameters of t.sub.21, t.sub.32, t.sub.43 and l into the following formula to obtain an estimated value of a target distance d: $d=\frac{.Math..Math.t_{21}\left(.Math..Math.t_{21}+.Math..Math.t_{32}-.Math..Math.t_{43}\right)}{.Math..Math.t_{32}\left(.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.Math.l$ wherein l is a length of T.sub.x1-R.sub.x1; step 4: substituting parameters of t.sub.21, t.sub.32, t.sub.43, l, h and into the following formula to obtain an estimated value of an inclined angle of a target track: $={\tan }^{-1}\left(\frac{1}{\frac{l}{h.Math..Math.\sin .Math..Math.}.Math.\frac{.Math..Math.t_{21}-.Math..Math.t_{43}}{.Math..Math.t_{32}}-\frac{1}{\tan .Math..Math.}}\right)$ wherein h is a length of R.sub.x1-R.sub.x2 and is an included angle between T.sub.x1-T.sub.x2 and T.sub.x2-R.sub.x2; and step 5: substituting parameters of t.sub.2, t.sub.32, t.sub.43, l, h and into the following formula to obtain an estimated value of a moving velocity v of the target: $v=\frac{\sqrt{h^2.Math..Math..Math.t_{32}^2.Math.{\sin }^2.Math.+{\left[l\left(.Math..Math.t_{21}-.Math..Math.t_{43}\right)-h.Math..Math..Math..Math.t_{32}.Math.\cos .Math..Math.\right]}^2}}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.$

6. The method for detection by using the forward acoustic scattering based double-transmitter and double-receiver networking target detection system according to claim 1, wherein the method comprises the following steps of estimating unknown parameters of d, v and when a target successively crosses T.sub.x1-R.sub.x1, T.sub.x1-R.sub.x2, T.sub.x2-R.sub.x1 and T.sub.x2-R.sub.x2 at uniform velocity v along a straight line, with a horizontal distance from a crossing point of the target on the transmitting-receiving connection line T.sub.x1-R.sub.x1 to R.sub.x1 marked as d and an included angle between a target track and the transmitting-receiving connection line T.sub.x1-R.sub.x1 marked as : step 1: extracting time of the target crossing transmitting-receiving connection lines by adopting a direct wave suppression method, wherein since four transmitting-receiving connection lines exist under a double-transmitter double-receiver configuration, four time are successively marked as t.sub.1, t.sub.2, t.sub.3 and t.sub.4 according to a time sequence; step 2: calculating corresponding moving time intervals when the target crosses the four transmitting-receiving connection lines as t.sub.21=t.sub.2t.sub.1, t.sub.32=t.sub.3t.sub.2 and t.sub.43=t.sub.4t.sub.3; step 3: substituting parameters of t.sub.21, t.sub.32, t.sub.43 and l into the following formula to obtain an estimated value of a target distance d: $d=-\frac{\left(.Math..Math.t_{21}+.Math..Math.t_{32}\right).Math.\left(.Math..Math.t_{21}-.Math..Math.t_{32}-.Math..Math.t_{43}\right)}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.Math.l$ wherein l is a length of T.sub.x1-R.sub.x1; step 4: substituting parameters of t.sub.21, t.sub.32, t.sub.43, l, h and into the following formula to obtain an estimated value of an inclined angle of a target track: $={\tan }^{-1}\left(\frac{1}{\frac{l}{h.Math..Math.\sin .Math..Math.}.Math.\frac{.Math..Math.t_{43}-.Math..Math.t_{21}}{.Math..Math.t_{32}}-\frac{1}{\tan .Math..Math.}}\right)$ wherein h is a length of R.sub.x1-R.sub.x2 and is an included angle between T.sub.x1-T.sub.x2 and T.sub.x2-R.sub.x2; and step 5: substituting parameters of t.sub.21, t.sub.32, t.sub.43, l, h and into the following formula to obtain an estimated value of a moving velocity v of the target: $v=\frac{\sqrt{h^2.Math..Math..Math.t_{32}^2.Math.{\sin }^2.Math.+{\left[l\left(.Math..Math.t_{43}-.Math..Math.t_{21}\right)-h.Math..Math..Math..Math.t_{32}.Math.\cos .Math..Math.\right]}^2}}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.$

Description

DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 shows a schematic diagram of a forward acoustic scattering based double-transmitter double-receiver detection network (parallelogram layout-crossing case 1);

[0033] FIG. 1 shows a schematic diagram of a forward acoustic scattering based double-transmitter double-receiver detection network (parallelogram layout-crossing case 2);

[0034] FIG. 3 shows a schematic diagram of a forward acoustic scattering based double-transmitter double-receiver detection network (rectangle layout-crossing case 1); and

[0035] FIG. 4 shows a schematic diagram of a forward acoustic scattering based double-transmitter double-receiver detection network (rectangle layout-crossing case 2).

DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention is further described in combination with embodiments and drawings.

[0037] A target detection system comprises two transmitting ends and two receiving ends; the two transmitting ends and the two receiving ends are anchored at a sea bottom, and formed in a parallelogram layout; the two transmitting ends are respectively marked as T.sub.x1 and T.sub.x2; the two receiving ends are respectively marked as R.sub.x1 and R.sub.x2; T.sub.x1-R.sub.x1, R.sub.x1-R.sub.x2, R.sub.x2-T.sub.x2 and T.sub.x2-T.sub.x1 form four edges of the parallelogram; T.sub.x1-R.sub.x2 and T.sub.x2-R.sub.x1 are two diagonal lines of the parallelogram; a length of T.sub.x1-R.sub.x1 is marked as l; a length of R.sub.x1-R.sub.x2 is marked as h; an included angle between T.sub.x1-T.sub.x2 and T.sub.x2-R.sub.x2 is marked as ; formed four transmitting-receiving connection lines are: T.sub.x1-R.sub.x1, T.sub.x1-R.sub.x2, T.sub.x2-R.sub.x1 and T.sub.x2-R.sub.x2; and depths of the transmitting ends and the receiving ends are equal.

[0038] Firstly, derivation processes of estimation formulas of a target distance d, a moving velocity v and a track angle are given.

[0039] In FIG. 1, two transmitting ends T.sub.x1 and T.sub.x2 are respectively located at A point and B point; and two receiving ends R.sub.x1 and R.sub.x2 are respectively located at C point and D point. Positions and connection lines of the transmitting ends and the receiving ends form a parallelogram, wherein |AC|=1, |CD|=h, and an included angle between AB and BD is marked as . In this way, four transmitting-receiving connection lines are formed: AC(T.sub.x1-R.sub.x1), BC(T.sub.x1-R.sub.x2), AD(T.sub.x1-R.sub.x2) and BD (T.sub.x2-R.sub.x2).

[0040] The target successively crosses the four transmitting-receiving connection lines of AC, BC, AD and BD at a constant velocity v along a straight track, and crossing points of the target and the four transmitting-receiving connection lines are marked as E, F, G and H. A horizontal distance from the crossing point E of the target on AC to the crossing point C (R.sub.x1) is marked as d, and an included angle between the target track and AC is marked as . Vertical lines are respectively made to AC from three crossing points F, G and H, and crossed at P point, Q point and R point.

[0041] According to a triangle similarity relationship: CFE111BFH, a formula is obtained

[00007]$\begin{array}{cc}.Math.\mathrm{BH}.Math.=\frac{.Math..Math.t_{32}+.Math..Math.t_{43}}{.Math..Math.t_{21}}.Math.d.& \left(1\right)\end{array}$

[0042] According to a triangle similarity relationship: AGEDGH, a formula is obtained

[00008]$\begin{array}{cc}.Math.\mathrm{DH}.Math.=\frac{.Math..Math.t_{43}}{.Math..Math.t_{21}+.Math..Math.t_{32}}.Math.\left(l-d\right).& \left(2\right)\end{array}$

[0043] Since |BH|+|DH|=1, formula (1) and formula (2) are substituted into the formula to obtain

[00009]$\begin{array}{cc}d=\frac{.Math..Math.t_{21}\left(.Math..Math.t_{21}+.Math..Math.t_{32}-.Math..Math.t_{43}\right)}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.Math.l.& \left(3\right)\end{array}$

[0044] In a right triangle EHR, |ER|=h sin /tan , and substituted into |ER|+|DH|+h cos =d to obtain

[00010]$\begin{array}{cc}={\tan }^{-1}\left(\frac{1}{\frac{l}{h.Math..Math.\sin .Math..Math.}.Math.\frac{.Math..Math.t_{21}-.Math..Math.t_{43}}{.Math..Math.t_{32}}-\frac{1}{\tan .Math..Math.}}\right).& \left(4\right)\end{array}$

[0045] In a right triangle EHR,

[00011]$\begin{array}{cc}{.Math.\mathrm{EH}.Math.}^2={.Math.\mathrm{HR}.Math.}^2.Math.\left(1+\frac{1}{{\tan }^2.Math.}\right).& \left(5\right)\end{array}$

[0046] Formula (4) is substituted into formula (5) to obtain

[00012]$\begin{array}{cc}.Math.\mathrm{EH}.Math.=\frac{1}{.Math..Math.t_{32}}.Math.\sqrt{.Math..Math.t_{32}^2.Math.h^2.Math.{\sin }^2.Math.+{\left[l\left(.Math..Math.t_{21}-.Math..Math.t_{43}\right)-h.Math..Math..Math..Math.t_{32}.Math.\cos .Math..Math.\right]}^2}.& \left(6\right)\\ \mathrm{Since}.Math..Math..Math.\mathrm{EH}.Math.=v\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right),\mathrm{then}& \\ v=\frac{\sqrt{.Math..Math.t_{32}^2.Math.h^2.Math.{\sin }^2.Math.+{\left[l\left(.Math..Math.t_{21}-.Math..Math.t_{43}\right)-h.Math..Math..Math..Math.t_{32}.Math.\cos .Math..Math.\right]}^2}}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.& \left(7\right)\end{array}$

[0047] In FIG. 2, two transmitting ends T.sub.x1 and T.sub.x2 are respectively located at A point and B point; and two receiving ends R.sub.x1 and R.sub.x2 are respectively located at C point and D point. Positions and connection lines of the transmitting ends and the receiving ends form a parallelogram, wherein |AC|=1, |CD|=h, and an included angle between AB and BD is marked as a. In this way, four transmitting-receiving connection lines are formed: AC(T.sub.x1-R.sub.x1), BC(T.sub.x1-R.sub.x2), AD(T.sub.x1-R.sub.x2) and BD (T.sub.x2-R.sub.x2).

[0048] The target successively crosses the four transmitting-receiving connection lines of AC, AD, BC and BD at a constant velocity v along a straight track, and crossing points of the target and the four transmitting-receiving connection lines are marked as E, F, G and H. A horizontal distance from the crossing point E of the target on AC to the crossing point C (R.sub.x1) is marked as d, and an included angle between the target track and AC is marked as . Vertical lines are respectively made to AC from three crossing points F, G and H, and crossed at P point, Q point and R point.

[0049] According to a triangle similarity relationship: AFEDFH, a formula is obtained

[00013]$\begin{array}{cc}.Math.\mathrm{DH}.Math.=\frac{.Math..Math.t_{32}+.Math..Math.t_{43}}{.Math..Math.t_{21}}.Math.\left(l-d\right).& \left(8\right)\end{array}$

[0050] According to a triangle similarity relationship: CGEBGH, a formula is obtained

[00014]$\begin{array}{cc}.Math.\mathrm{BH}.Math.=\frac{.Math..Math.t_{43}}{.Math..Math.t_{21}+.Math..Math.t_{32}}.Math.d.& \left(9\right)\end{array}$

[0051] Since |BH|+|DH|=1, formula (8) and formula (9) are substituted into the formula to obtain

[00015]$\begin{array}{cc}d=-\frac{\left(.Math..Math.t_{21}+.Math..Math.t_{32}\right).Math.\left(.Math..Math.t_{21}-.Math..Math.t_{32}-.Math..Math.t_{43}\right)}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.Math.l.& \left(10\right)\end{array}$

[0052] In a right triangle EHR, |ER|=h sin /tan() and substituted into |BH|h cos +|ER|=1d to obtain

[00016]$\begin{array}{cc}={\tan }^{-1}\left(\frac{1}{\frac{.Math..Math.t_{43}-.Math..Math.t_{21}}{.Math..Math.t_{32}}.Math.\frac{l}{h.Math..Math.\sin .Math..Math.}-\frac{1}{\tan .Math..Math.}}\right).& \left(11\right)\end{array}$

[0053] In a right triangle EHR,

[00017]$\begin{array}{cc}{.Math.\mathrm{EH}.Math.}^2={.Math.\mathrm{HR}.Math.}^2.Math.\left(1+\frac{1}{{\tan }^2.Math.}\right).& \left(12\right)\end{array}$

[0054] Formula (11) is substituted into formula (12) to obtain

[00018]$\begin{array}{cc}.Math.\mathrm{EH}.Math.=\frac{1}{.Math..Math.t_{32}}.Math.\sqrt{.Math..Math.t_{32}^2.Math.h^2.Math.{\sin }^2.Math.+{\left[l\left(.Math..Math.t_{43}-.Math..Math.t_{21}\right)-h.Math..Math..Math..Math.t_{32}.Math.\cos .Math..Math.\right]}^2}.& \left(13\right)\\ \mathrm{Since}.Math..Math..Math.\mathrm{EH}.Math.=v\left(.Math..Math.t.Math..Math.21+.Math..Math.t.Math..Math.32+.Math..Math.t.Math..Math.43\right),\mathrm{then}& \\ v=\frac{\sqrt{.Math..Math.t_{32}^2.Math.h^2.Math.{\sin }^2.Math.+{\left[l\left(.Math..Math.t_{43}-.Math..Math.t_{21}\right)-h.Math..Math..Math..Math.t_{32}.Math.\cos .Math..Math.\right]}^2}}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.& \left(14\right)\end{array}$

[0055] When =90, a parallelogram layout shown in FIG. 1 is simplified as a rectangle layout shown in FIG. 3. In this case, a calculation formula of the target distance d, the inclined angle of the track and the moving velocity v can be simplified as follows:

[00019]$\begin{array}{cc}d=\frac{.Math..Math.t_{21}\left(.Math..Math.t_{21}+.Math..Math.t_{32}-.Math..Math.t_{43}\right)}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.Math.l,& \left(15\right)\\ ={\tan }^{-1}\left(\frac{h}{l}.Math.\frac{.Math..Math.t_{32}}{.Math..Math.t_{21}-.Math..Math.t_{43}}\right),& \left(16\right)\\ v=\frac{\sqrt{.Math..Math.t_{32}^2.Math.h^2+{\left(.Math..Math.t_{21}-.Math..Math.t_{43}\right)}^2.Math.l^2}}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.& \left(17\right)\end{array}$

[0056] When =90, a parallelogram layout shown in FIG. 2 is simplified as a rectangle layout shown in FIG. 4. In this case, a calculation formula of the target distance d, the inclined angle of the track and the moving velocity v can be simplified as follows:

[00020]$\begin{array}{cc}d=-\frac{\left(.Math..Math.t_{21}+.Math..Math.t_{32}\right).Math.\left(.Math..Math.t_{21}-.Math..Math.t_{32}-.Math..Math.t_{43}\right)}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.Math.l,& \left(18\right)\\ ={\tan }^{-1}\left(\frac{h}{l}.Math.\frac{.Math..Math.t_{32}}{.Math..Math.t_{43}-.Math..Math.t_{21}}\right),& \left(19\right)\\ v=\frac{\sqrt{.Math..Math.t_{32}^2.Math.h^2+{\left(.Math..Math.t_{43}-.Math..Math.t_{21}\right)}^2.Math.l^2}}{.Math..Math.t_{32}\left(.Math..Math.t_{21}+.Math..Math.t_{32}+.Math..Math.t_{43}\right)}.& \left(20\right)\end{array}$

[0057] An application example is given in a second part. Firstly, FIG. 1 is taken as an example for description. It is assumed that l=1000 m, h=500 m and =60. The target successively crosses the transmitting-receiving connection lines of AC, BC, AD and BD at a velocity v=2.5 m/s along a straight line; a horizontal distance from the crossing point on AC to point C is d=500 m; and the inclined angle of the track is 80. Relative to a certain reference time (t=0), four crossing time extracted by a direct wave suppression method are respectively t.sub.1=100 s, t.sub.2=166.3 s, t.sub.3=230.6 s and t.sub.4=275.9 s. Then, moving time intervals are calculated: t.sub.21=66.3 s, t.sub.32=64.3 s and t.sub.43=45.3 s. Related parameters are successively substituted into formula (3), formula (4) and formula (7) to obtain the following estimated values: d499.7 m, 80.03, and v2.49 m/s.

[0058] Taking FIG. 2 as an example, it is assumed that l=1000 m, h=500 m and =60. The target successively crosses the transmitting-receiving connection lines of AC, AD, BC and BD at a velocity v=2.5 m/s along a straight line; a horizontal distance from the crossing point on AC to point C is d=500 m; and the inclined angle of the track is 133. Relative to a certain reference time (t=0), four crossing time extracted by a direct wave suppression method are respectively t.sub.1=100 s, t.sub.2=202.6 s, t.sub.3=240 s and t.sub.4=336.8 s. Then, moving time intervals are calculated: t.sub.21=102.6 s, t.sub.32=37.4 s and t.sub.43=96.8 s. Related parameters are successively substituted into formula (10), formula (11) and formula (14) to obtain the following estimated values: d499.3 m, 133.1 and v2.50 m/s.

[0059] The direct wave suppression method in the present embodiment adopts the direct wave suppression method based on adaptive interference cancellation proposed in patent ZL201418002697.7 to extract the time of the target crossing the transmitting-receiving connection lines.

[0060] The present invention obtains obvious implementation effects in typical embodiments. The forward acoustic scattering based double-transmitter double-receiver networking target detection method is convenient in operation, and simple in algorithm, has good robustness, can be used for detecting underwater targets in important ports, sea channels, straits and the like, and has wide application prospect.