JPH0720230A - Sonar depression angle controller - Google Patents

Abstract

PURPOSE:To make automatic control possible accurately considering the refraction or the like of sounds in the control of a depression angle of a beam of a sonar. CONSTITUTION:A vertical beam area is calculated with an optimum beam depression angle calculating section 5 considering the refraction of sounds from various pieces of information from a sonar 2, a water temperature measuring device 3 and a navigator 4, signal excess level calculating conditions inputted from an input part 6, the vertical beam area inputted from a data registering section 7, a signal excess calculation parameter and the like. Calculation of the position of a target is performed from various pieces of information to be inputted from the sonar 2 and the navigator 4 in the detection of the target. Thereafter, when the position of the target is deviated from a reference in the vertical beam area with the moving of a ship, the depression angle of a beam is changed thereby controlling the depression angle at such a position on a center sound line that a signal excess level is at its maximum or positive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sonar depression angle control device, and more particularly, it searches for a target on the seabed or a target supported near the seabed by using a beam having directivity in the vertical direction and variably controllable in the depression direction. The present invention relates to a sonar beam depression angle control device.

[0002]

2. Description of the Related Art A schematic configuration of a conventional sonar depression angle control device is shown in FIG. The sonar automatic depression angle control device 1 has an optimum beam depression angle calculation unit 5 for calculating an optimum beam, and a detection target 8 obtained from the sonar 2
Based on the distance RTO to (see FIG. 15) and the water depth ZTO obtained from the navigation device 4, as shown in FIG. 15, the optimum beam depression angle θB1 is calculated geometrically (using a trigonometric function). There is.

[0003]

In the conventional sonar depression angle control device as described above, the optimum beam depression angle is geometrically calculated only by the two parameters of the water depth and the detection target distance. There is a drawback that accurate automatic depression angle tracking cannot be performed because the sound is bent in the vertical direction and propagated due to changes in the water temperature and water pressure in the direction.

An object of the present invention is to provide a sonar depression angle control device for accurately calculating the beam depression angle in consideration of sound refraction and the like.

Another object of the present invention is to provide a depression angle control device for a sonar, which is adapted to accurately perform automatic depression angle tracking of a detection target as a ship moves.

[0006]

A sonar depression angle control device according to the present invention is a sonar depression angle control device for searching a target on the seabed using a beam having directivity in a vertical direction, at a set depression angle of the sonar. The beam center sound ray is calculated in consideration of the vertical distribution of the water temperature, and the means for obtaining the intersection point of this sound ray and the sea bottom, and the direct distance which is the target distance detected by the sonar, the sonar depth and the water depth are used to determine the water temperature. A means for calculating the seabed position of the detection target by performing sound ray calculation while considering the vertical distribution, and a means for calculating the depression angle at which the intersection and the seabed position are matched to perform the transmission / reception depression angle control of the sonar. Characterize.

Another sonar depression angle control device according to the present invention is a sonar depression angle control device that searches for a target on the seabed using a beam having vertical directivity, which is the target distance detected by the sonar. The sound ray calculation is performed from the direct distance, the sonar depth and the water depth while considering the vertical distribution of the water temperature, and the signal surplus level for the target in the area where the sonar beam based on the calculated sound ray intersects the seabed is calculated by the sonar. Of the target seabed position by calculating the sound ray while considering the vertical distribution of the water temperature from the means for calculating from the performance value of the seabed and the reflection loss of the seabed and further the sound wave propagation loss, and the direct distance and the sonar depth and the water depth. And a means for calculating a depression angle at which the maximum seafloor position of the signal surplus level and the detection target seafloor position are coincident with each other to control the transmission / reception depression angle of the sonar. The features.

Another sonar depression angle control device according to the present invention, in addition to the above-mentioned configuration, further calculates a signal surplus level based on a preset detection probability, and determines the signal surplus level at two near and far seabed positions where the signal surplus level is positive. On the other hand, when the ship approaches the target, the depression angle at which the near position and the seabed position of the detection target match is calculated, and when the ship departs from the target, the depression angle at which the far position and the seabed position of the target position match. Is included to control the transmission / reception depression angle of the sonar.

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic block diagram of an embodiment of the present invention, in which the optimum beam depression angle calculation unit 5 uses the data from the sonar 2, the water temperature detection unit 3, the navigation device 4, the input unit 6, and the data registration unit 7. Based on this, the optimum beam depression angle is calculated.

The procedure for calculating the optimum beam depression angle will be described in detail below with reference to FIGS.

Based on the sonar operation mode and the beam depression angle θBO input from the sonar 2, the sonar beam width (see FIG. 4) output from the data registration unit 7 and the water temperature distribution with respect to the depth input from the water temperature measuring device 3 From the above, the vertical beam region (see FIGS. 2 and 3) and the acoustic line of the beam depression angle θBO (beam central acoustic line) are calculated.

As shown in FIG. 2, the sound ray is a line representing the way the sound propagates at the sound emission angle, and is assumed to be composed of n sampling points given at a constant distance Δl. Considering this, each sampling position is approximately calculated by Snell's law by the following procedure.

The coordinates of the initial sampling position (sonar position) are horizontal distance X0 and depth Z0. The sound emission angle is θ0. From the vertical distribution of the water temperature, the sound velocity C0 at the depth Z0 is calculated by the Leroy formula.

Then, the next sampling position (X1, Z1) advanced by the distance of the sampling interval Δl is calculated by X1 = X0 + Δlcos θ0 Z1 = Z0 + Δlsin θ0. The sound velocity C1 at this depth Z1 is similarly obtained by the Leroy equation.

Next, according to Snell's law, the sound emission angle θ1 at the sample position (X1, Z1) is given by

[0017]

[Equation 1]

It is calculated by the following equation.

After that, by calculating each sampling position one after another using each of the above-mentioned procedures, the central ray of the beam can be obtained in consideration of the vertical distribution of the water sound. The beam center sound ray is a sound ray when the emission angle of the sound at the initial sampling position (soner position) is the beam depression angle θB0.

Next, from the water depth data input from the navigation device 4, the intersection of the beam center sound ray and the seabed is obtained and X in FIG.
Calculate T1. In this case, an intersection (XBt, ZT0) between the beam center sound ray and the water depth (sea bottom) ZT0 previously obtained is obtained, and from this intersection and the sonar position (X0, Z0), XT1 = XBT-X0 XT1 of is calculated.

Then, the target position PT0 is obtained from the detected distance RS0 (the direct distance between the sonar 2 and the target 8) RS0 input from the sonar 2, the water depth ZT0, and the water temperature distribution data, and the horizontal distance XT0 is calculated. (See FIG. 3).

The method of calculating the target position PT0 is as follows. First, as input information, the water depth ZT0 at the time of detecting the target of the navigation device 4, the vertical distribution of the water temperature of the water temperature measuring device 3, and the sonar beam width of the data registration unit 7 are given. And FIG.
As shown in, sampling launch angle in sonar beam △
Assume N sound rays denoted by θ.

In the range from the sonar to the seabed, the Mth (M
= 1, 2, ..., N) sound ray calculation is performed, and sound ray length L
M is calculated as LM = (sum of sampling intervals Δl) + (intersection between sound ray and seabed, distance ΔlEND between last sampling points) (see FIG. 5).

Then, a sound ray whose length LM is equal to the detection distance RSO is searched, and the intersection of the sound ray whose length is equal to the seabed is set as the detection target position PT0 (XT0, ZT0). .

As shown in FIG. 7, when the detection target 8 no longer exists on the central sound ray due to the movement of the ship, the position of the detection target 8 in the vertical beam region (front side or outside with respect to the central sound ray). Or) exists.

In this determination, it is assumed that the water depth ZT0 and the positional relationship between the sonar and the vertical beam region (sound ray) do not change as a prerequisite. Under this condition,
Horizontal distance XT0 from the sonar to the target (XT0 changes when the ship moves forward or backward) and horizontal distance XT1 from the sonar to the intersection of the center ray and the seabed (XT1 even while the ship is moving)
Is fixed).

That is, when XT0 <XT1, it is determined to be on the front side of the central sound ray, and when XT0> XT1, it is determined to be outside the central sound ray (see FIG. 6).

When the detection target 8 is on the front side of the central sound ray, the beam depression angle is changed in the increasing direction, and when it is on the outer side, the beam depression angle is changed to the decreasing direction, and the depression angles at which the horizontal distances XT0 and XT1 coincide ( Calculate the optimum beam depression angle θB1) (Fig. 6)
reference).

The optimum beam depression angle θB1 is obtained as follows by changing the beam depression angle θB0 which is the emission angle of the central sound ray and recalculating the central sound ray.

When the detection target is on the front side of the central sound ray, the change direction of the beam depression angle θB0 (the emission angle of the central sound ray) is changed to
Increase (θB0 + Δθ), and if it is outside, decrease (θB0-Δθ).

The central sound ray thus changed is recalculated. And the horizontal distance XT0 from the sonar to the detection target
And the central sound ray recalculated from the sonar and the seabed (water depth Z
Calculate the horizontal distance XT1 to the intersection with (T0).

When the horizontal distances XT1 and XT0 are compared and the distances are different from each other, the above change in the beam depression angle (± Δ) is again performed.
θ) Return to processing. When they match, the beam depression angle used to calculate the central sound ray is set as the optimum beam depression angle θB1.

Next, another embodiment of the present invention will be described. The configuration of this embodiment is the same as that of the block of FIG. 1, but the calculation procedure of the optimum beam depression angle calculation unit 5 is different and will be described in detail below.

Based on the sonar operation mode and the beam depression angle θB0 input from the sonar 2, from the sonar beam width output from the data registration section 7 and the temperature distribution data for the depth input from the water temperature measuring device 3, Beam area (see FIG. 2) and sound ray calculation are performed. Further, the sound wave propagation loss is calculated from the water depth data input from the navigation device 4 in the range where the vertical beam region and the sea bottom intersect.

The sound wave propagation loss TL is a loss level indicating how much the sonar transmission level (firing sound level) is attenuated during underwater propagation.

[0036]

[Equation 2]

It is calculated by

Where r is the length of the sound ray LM (M = 1 to 1)
N), and α is the damping coefficient [dB / kyd] (THOR
Calculation by the formula of P) is shown.

N sound ray calculations are performed in the vertical beam region,
The length LM (M = 1 to N) of each sound ray and the intersection of the sound ray and the seabed are calculated. Then, using the sound ray length LM, the sound wave propagation loss T at the intersection of each sound ray and the seabed
LM (M = 1 to N) is calculated by the above formula (see FIG. 8).

Based on the sonar operation mode input from the sonar 2, the transmission level, beam characteristics, dome noise characteristics output from the data registration section 7, and further the input section 6
Based on the seabed quality set in step 1, the signal surplus level in the range where the vertical beam region and the seabed shown in FIG. 9 intersect from the seabed scattering intensity output from the data registration unit 7 and the sound wave propagation loss TL obtained previously. Is calculated.

Signal surplus level SE (Signal Ex)
cess) indicates the level difference between the signal level and the residual sound level at a certain position in the sonar beam,
It is calculated by the following formula. Incidentally, when SE> 0, it has a characteristic that a target can be detected with the set target detection probability.

The signal surplus level SE is obtained by SE = SL-2TL + TS-NRL-RD. SL is a sonar transmission level, 2TL is a round trip propagation loss level, TS is a target string (which varies depending on the target to be detected), NRL is noise and reverberation level, and RD is a recognition differential (which varies depending on the detection probability).

The signal surplus level SEM (M = 1 to 1) at the intersection of each sound ray and the seabed obtained when calculating the sound wave propagation loss TL.
N) is calculated by the above formula. At this time, SL, TS, N
The data of the data registration unit 7 is used for RL and RD, and the calculated value is used for TL.

The horizontal distance between the sonar and the position (intersection between the sound ray M and the seabed) where the level is maximum in the SEM calculated in this way is calculated as XT2 (see FIG. 10).

Next, the detection distance input from the sonar 2 (the distance RS0 between the sonar and the target, the water depth ZT0 input from the navigation device 4, and the water temperature distribution data with respect to the depth input from the water temperature measuring device 3) From the above, the detection target position PT0 is obtained by the same method as described in the first embodiment,
Calculate the horizontal distance XT0.

When the target 2 does not exist on the position where the maximum signal surplus level is present due to the movement of the ship (FIG. 9),
By changing the beam depression angle in the increasing or decreasing direction, the depression angle (optimum beam depression angle θ
B1) is calculated (see FIG. 10).

In the system of the second embodiment, the beam depression angle is controlled so that the target detection probability becomes highest as compared with the system of the first embodiment, so that stable tracking is possible.

Next, the third embodiment will be described below. Based on the sonar operation mode and the beam depression angle θB0 input from the sonar 2, from the sonar beam width input from the data registration unit 7 and the water temperature distribution with respect to the depth input from the water temperature measuring device 3, the vertical beam area (Fig. 2)) and sound ray calculation, and further, from the water depth data input from the navigation device 4, in the range where the vertical beam region and the seabed intersect, the sound wave propagation loss TL is calculated in the same manner as in the second embodiment. To do.

Then, based on the sonar operation mode input from the sonar 2, based on the transmission level from the data registration section 7, the beam characteristics, the dome noise characteristics, and the seabed quality set by the input section 6, From the seabed scattering intensity from the data registration unit 7, the target detection probability value set by the input unit 6, and the sound wave propagation loss described above, the signal surplus level of the signal surplus level is determined in the range where the vertical beam region and the seabed described above intersect. Calculation is performed (see FIG. 11).

Then, the lower limit XT3 and the upper limit XT4 of the horizontal distance where the signal surplus level is positive (the signal surplus level is positive when the target detection is possible by the set target detection establishment) are obtained (FIG. 12 and FIG. 12). 13).

Next, from the detected distance (the direct distance between the sonar and the target) RS0 input from the sonar 2, the water depth ZT0 input from the navigation device 4, and the water temperature distribution data for the depth input from the water temperature measuring device 3. , The detection target position PT0 is obtained, and the horizontal distance XT0 is calculated (see FIG. 3).

When the detection target 8 does not exist at the position where the signal surplus level becomes positive with the movement of the ship (see FIG. 11) and the ship is moving forward, the horizontal distances XT0 and XT3 become Calculate the matching depression angle (optimum beam depression angle θB1). When the ship is moving backward, the depression angle at which XT0 and XT4 match (optimum beam depression angle θB1) is calculated (see FIG. 12).

In the third embodiment, the beam depression angle .theta.B0 is automatically controlled according to the optimum beam depression angle .theta.B1 output from the sonar automatic depression angle control device 1 to automatically detect the depression angle of the detection target.

[0054]

As described above, according to the present invention, the vertical beam area is calculated for each movement of the ship even when the sound is propagated while being bent in the vertical direction, and the target is set to the central sound ray or set. By calculating the optimum beam depression angle so as to be at the position of the signal surplus level, there is an effect that an accurate automatic depression angle tracking becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing a concept of central sound ray calculation.

FIG. 3 is a diagram showing a concept of calculating a detection target position.

FIG. 4 is a conceptual diagram of calculation of a detection target position and a horizontal distance.

FIG. 5 is a conceptual diagram for calculating a sound ray length LM.

FIG. 6 is a conceptual diagram of optimum beam depression angle calculation in the first embodiment.

FIG. 7 is a diagram showing a positional relationship between a vertical beam region and a detection target when the ship is moving.

FIG. 8 is a diagram showing a calculation range when calculating a sound wave propagation loss.

FIG. 9 is a diagram showing a relationship between a detection target position and a maximum signal surplus level position.

FIG. 10 is a conceptual diagram of optimum beam depression angle calculation in the second embodiment.

FIG. 11 is a diagram showing a relationship between a detection target position and a signal surplus level position.

FIG. 12 is a conceptual diagram of optimum beam depression angle calculation in the third embodiment.

FIG. 13 is a diagram showing a detailed relationship between a detection target position and a signal surplus level position.

FIG. 14 is a block diagram of a conventional sonar depression angle control device.

FIG. 15 is a conceptual diagram of a conventional optimum beam depression angle calculation method.

[Explanation of symbols]

 1 Automatic sonar depression angle control device 2 Sonar 3 Water temperature measuring device 4 Navigation device 5 Optimal beam depression angle calculation unit 6 Input unit 7 Data registration unit 8 Detection target

Claims (3)

[Claims] 1. A depression angle control device for a sonar, which searches a target on the seabed using a beam having directivity in a vertical direction, wherein a beam center sound ray at a depression angle set by the sonar is considered in consideration of a vertical distribution of water temperature. A sound ray calculation is performed by taking into account the vertical distribution of the water temperature from the means for calculating the intersection of the sound ray and the seabed and the direct distance which is the target distance detected by the sonar and the sonar depth and water depth. A sonar depression angle control device, and means for calculating a depression angle at which the intersection and the seabed position coincide with each other to perform a transmission / reception depression angle control of the sonar. 2. A depression angle control device for a sonar, which searches for a target on the seabed using a beam having directivity in a vertical direction, comprising: a direct distance, which is a target distance detected by the sonar, a sonar depth, and a water depth. , The sound ray calculation is performed in consideration of the vertical distribution of the water temperature, and the signal surplus level for the target in the area where the sonar beam based on the calculated sound ray intersects the seabed is calculated as the sonar's capability value and the seafloor reflection loss. Further, means for calculating from sound wave propagation loss, means for calculating the target seabed position by performing sound ray calculation from the direct distance, sonar depth and water depth while considering the vertical distribution of water temperature, and the signal surplus level. A sonar depression angle control device for calculating the depression angle at which the maximum seabed position of the above and the detection target seabed position are coincident with each other to control the transmission / reception depression angle of the sonar. 3. A signal surplus level based on a preset detection probability is calculated, and when the ship approaches a target, the near position and the detection are detected as the two seabed positions where the signal surplus level is positive. A means for calculating a depression angle at which the target seabed position matches and calculating a depression angle at which the distant position and the seabed position at the target position match when the ship departs from the target to control the depression and reception of the sonar. The sonar depression angle control device according to claim 2.