JPH06102345A - System for acoustic simulation of target used for active sonar - Google Patents

Abstract

PURPOSE:To simulate the acoustic signature of a target used for an active sonar, which is inexpensive, small in scale and accurate. CONSTITUTION:A computer means calculates out the target strength of an underwater travelling body and the like linked with only an aspect plane according to the incoming direction of a pulse detected by an azimuth sensor 11, and at the same time calculates the extension of a target echo in accordance with the incoming direction of a pulse and the width of a pulse detected by a pulse sensor 12 and at the same time calculates out a doppler. An acoustic converter means provides a simulated acoustic output in accordance with the target strength, the target echo and the doppler. In that case, when a data base 14 with simulated acoustic data built in according to the incoming direction of a pulse and the width of a pulse is provided, the computer means retrieves a data base in accordance with the incoming direction of a pulse and the width of a pulse to send out the output of simulated sound.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to simulating target acoustic signatures for active sonar.

[0002]

2. Description of the Related Art An acoustic signature of an active sonar for underwater and overwater targets (hereinafter sometimes referred to as "underwater target, etc.") consists of target strength, target echo extension, Doppler, reflected sound quality, etc. Testing and training with these real acoustic signatures
Due to cost, safety, and flexibility constraints, alternative systems that simulate acoustics have been used.

FIG. 2 is a diagram for explaining a target acoustic simulation system for an active sonar used as a conventional stationary target. In FIG. 2, reference numeral 21 denotes an underwater vehicle of the active homing system (hereinafter sometimes referred to as "underwater vehicle"), which travels in the sea.
22 is a watercraft or the like. The underwater vehicle 21, the watercraft 22 and the like are equipped with an active sonar. A hydrophone 23 is an underwater vehicle 21 or a watercraft, etc. 2
The ultrasonic pulse signal radiated from the active sonar 2 is received, and the simulated acoustic signature is output according to the received ultrasonic pulse signal to simulate as if an underwater target emits a reverberant sound. 24 is the sea level. Reference numeral 25 is a lead wire, and the hydrophone 23 is connected to one end of the lead wire 25. 26 is a float, which floats above the sea surface 24. In the housing of the float 26, a power supply and a signal processing device and a power supply for amplifying weak transmission pulses coming from the underwater vehicle 21 or the watercraft 22 to repeat and generate a simulated acoustic signature such as an underwater target. Built in.

Next, in the system configured as described above, the operation of the target acoustic simulation system for active sonar (hereinafter sometimes referred to as "underwater target etc.") used as a conventional stationary type target and The operation will be described. In FIG. 2, an underwater vehicle 21 injected into the sea radiates ultrasonic pulse signals from the tip sonar while traveling underwater, and a ship 22 on the water from the bottom sonar while radiating ultrasonic pulse signals. Search for targets, etc.

The hydrophone 23 such as an underwater target receives the ultrasonic pulse signal of the active sonar,
It outputs a simulated acoustic signature as if the underwater target emits a reverberant sound. To describe the process up to the output in a little more detail, a weak transmission pulse arriving from the underwater vehicle 21 or a ship 22 on the water is converted from acoustic energy to electric energy by the hydrophone 23,
After the signal is processed in the float 26 via the lead wire 25, the simulated acoustic signature raised to the level of the underwater target or the like is oscillated again via the hydrophone 23. The simulated acoustic signature is composed of target strength, Doppler, and echo expansion (constant), and outputs a pre-programmed (set) value before the underwater target is put into water.

Here, the target strength of the above-described simulated sound signature will be described.

In active sonar, the parameter target strength is related to the reverberant sound returning from an underwater target. Then, at a distance of 1 yard (about 0.9144 m) from the acoustic center of the target, the ratio of the intensity of the sound reflected from the target to the intensity of the sound incident from a distant sound source is 10 times the logarithm whose base is 10. Define as. That is, the target strength TS is

TS = (10 log (Ir / Ii)) _{r = 1} (1)

Here, the intensity of the reflected wave at Ir = 1 yard, Ii = the intensity of the incident wave

Here, in FIG.
Consider a plane wave of i is incident, if the radius of the sphere is a, power incident wave is blocked by the sphere,? pa ² I
i, and if the sphere reflects this power uniformly in all directions, the intensity of the reflected wave at a distance r yard from the sphere is the ratio of the power to the surface area of the sphere of radius r. That is,

Ir = πa ² Ii / 4πr ² = Ii · a ² / 4r ² (2)

[0012] Here, Ir is the intensity of reflection at the distance r. The reference distance of one yard ratio of intensity Ir strength of the incident wave and the reflected wave _{(Ir / Ii) r = 1} = a 2/4 (3)

And the target strength of the sphere is

[0014] TS = (10log (Ir / Ii )) r = 1 = 10log (a 2/4) (4)

[0015] Therefore, the radius is 2 yards (a = 2)
It is clear that the ideal sphere has a target strength of 0 dB.

[0016]

Regarding the target strength described above, in the omnidirectional transducer (omnidirectional), if it is set to a constant value (dB), the characteristics of the transducer Although there is some distortion, the same value (circle if there is no distortion) is obtained regardless of the direction of the underwater target, etc., and the pattern shows a pattern different from the actual target strength of the underwater target. Also,
The target echo shows acoustically different elongation depending on the aspect angle and the pulse width, but the elongation was set to be constant. Alternatively, there were some that did not set this growth. In addition, the Doppler changes depending on the aspect angle and speed, but in the case of the static type, the same Doppler according to the set value is repeated from any aspect angle, so it is a phenomenon different from the actual underwater target Doppler etc. . However, in the case of a mobile underwater target or the like, this problem does not occur. Further, in many cases, the target sound quality and the like are not taken into consideration in the above system.

Using such a target acoustic simulation system for an underwater target, etc., a high-level target categorization (determining whether or not the detected target is a real underwater target etc.) as an underwater target, etc., and target strength Not only when training with an underwater vehicle 21 having a homing system that also evaluates Doppler and target echo elongation, etc., or when testing the sonar signal processing capacity limit etc. using an underwater target etc. This system has a problem that the expected results cannot be obtained.

The problem to be solved by the present invention is that an inexpensive and small-scale system can accurately perform active
Sonar target acoustic signature, that is, target strength, target echo extension, Doppler, reflected sound quality, etc. can be systematically generated and simulated, and active training that can obtain advanced training evaluation and test accuracy close to an actual underwater target. To provide a target sound simulation system for sonar.

[0019]

In order to solve the above problems, a target acoustic simulation system for an active sonar according to the present invention is provided with an azimuth sensor for detecting the arrival direction of a pulse propagating in water, and a detection direction of the azimuth sensor. And a sound converting means for outputting a simulated sound corresponding to the target strength calculated by the calculating means.

In addition to the above configuration, a pulse sensor for detecting the arrival pulse width is further provided, the calculation means calculates the elongation of the target echo according to the arrival direction of the pulse and the pulse width, and the acoustic conversion means is the target. Outputs a simulated sound according to the extension of the echo.

Further, in addition to the above configuration, the calculation means calculates the Doppler corresponding to the arrival direction of the pulse with respect to the preset speed, and the acoustic conversion means outputs the simulated sound corresponding to the Doppler.

Further, it is provided with an angle detecting means for detecting its own posture angle, and the calculating means corrects the change angle detected by the angle detecting means with respect to the detection direction of the azimuth sensor to obtain the target strength and the target echo. Calculate elongation and Doppler.

Furthermore, a data base having simulated acoustic data according to the arrival direction of the pulse and the pulse width is provided,
Instead of the above calculation, the calculation means may search the database according to the arrival direction of the pulse and the pulse width.

With the above structure, the sound quality of the simulated sound calculated by the calculation means and emitted from the sound conversion means is such that the sound quality reflects metal sound or the sound quality reflected by installing the sound insulation tile on the metal hull surface.

Further, the calculation means corrects the value of the transmission level with respect to the aspect so that the direction characteristic of the acoustic conversion means becomes uniform in all directions.

Further, an external storage means is provided to store the detection direction of the azimuth sensor, the pulse width of the pulse sensor, the attitude angle data of the angle detection means, and the output data calculated by the calculation means or the retrieved search data. You may

The system may be mobile and at least the orientation sensor and the plurality of acoustic transducers may be mounted in an array towed by the mobile enclosure.

[0028]

The above-described structure operates as follows. The direction sensor detects a pulse propagating in water and detects the direction of arrival of the pulse with respect to a simulated system, that is, a simulated underwater target. The pulse sensor detects the incoming pulse width.

The calculating means calculates the target strength of the underwater vehicle linked only to the aspect plane according to the arrival direction of the pulse detected by the direction sensor, and detects the arrival direction of the pulse and the pulse sensor. The elongation of the target echo according to the pulse width is calculated. At this time, the calculation means calculates the Doppler corresponding to the direction in which the pulse arrives with respect to the speed of the underwater target simulated at this time.

The sound converting means outputs a simulated sound corresponding to the target strength calculated by the calculating means, the extension of the target echo, and the Doppler. At this time, when a data base containing simulated acoustic data mainly including acoustic measurement data of underwater vehicle according to the arrival direction of the pulse and the pulse width is provided, the calculation means replaces the above calculation. , The data according to the pulse arrival direction and pulse width.
The base is searched and a simulated sound is output.

These simulated sounds are subjected to signal processing by the calculation means so as to have a metal sound reflection sound quality or a reflection sound quality in which the metal hull surface is equipped with sound insulation tiles, and when the directional characteristics of the sound conversion means are not uniform. , Is corrected by the calculating means so that the value of the transmission level with respect to the aspect becomes uniform in all directions.

When the system is a stationary type, the calculation means corrects the detection direction of the azimuth sensor according to the change amount of the posture angle of the self detected by the angle detection means,
Calculate the target strength, target echo stretch and Doppler.

Since the external storage means is provided, the detection direction of the azimuth sensor, the pulse width of the pulse sensor, the attitude angle data of the angle detection means, and the output data calculated by the calculation means or the retrieved search data are necessary. Memorize it and use it for later examination.

If the system is mobile and at least the orientation sensor and the plurality of acoustic transducing means are mounted in an array towed by a mobile housing, the geometric positions of the plurality of acoustic transducing means and A more realistic simulation system is realized by the characteristics.

[0035]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a target acoustic simulation system for active sonar of the present invention. 11 is a direction sensor,
The directions of incoming echoes (pulses) of the active sonar of the underwater vehicle 21 and the watercraft 22 shown in FIG. 2 are measured. A pulse sensor 12 measures the pulse width of the incoming echo. Numeral 13 is a gyro, which measures a soft absolute angle with respect to the initial azimuth angle even if this system rotates hard due to a tidal current or the like, and maintains a constant simulated acoustic pattern according to the azimuth of the incoming echo. It is a thing. 1
Reference numeral 4 is a data base that constitutes a disk unit, and incorporates acoustic measurement data required for acoustic signature generation. Reference numeral 15 is a digital computer, and the orientation sensor 11
Aspect angle data obtained from the pulse sensor 12
Based on the pulse width data obtained from the gyro 13 and the attitude angle data obtained from the gyro 13, acoustic simulation calculation corresponding to the underwater target or acoustic measurement data on the data base 14 is searched. Reference numeral 16 is an omnidirectional (omnidirectional) hydrophone as a general-purpose transducer. Reference numeral 17 is a wave transmission / reception switch. Reference numeral 18 denotes an acoustic signal processing device, which receives incoming echoes (pulses) of an active sonar from an underwater vehicle 21 and a watercraft 22 shown in FIG. 2 with a hydrophone, and converts acoustic energy into electric energy. A target acoustic signature such as an underwater target is generated by the command of the digital computer 15 in the acoustic signal processing device 18 via the transducer switching device 17. This electrical acoustic signature is again oscillated into seawater as an acoustic signal from the hydrophone 16 after passing through the transducer switching unit 17. Reference numeral 19 is an external storage device, and if necessary, input detection data (direction sensor 11, pulse sensor 1
2, data from the gyro 13) and simulated output data (calculation or search data of the digital computer 15) are recorded.

Here, when the characteristics of the underwater target (for example, a submarine) with respect to the target strength and the aspect (direction of the underwater target or the like with respect to the sound flux line direction) are roughly summarized, it is considered that a butterfly pattern as shown in FIG. 4 is obtained. This butterfly pattern has the following features.

A sideways wing is about 25d
B is reached, which is caused by specular reflection.

(A) A stern aspect aspect is caused by the shadow and wake of the hull.

(C) The sub-pole approximately 20 degrees from the bow is 1-2 dB larger than the normal level of the pattern. This is probably due to internal reflection in the underwater target tank structure.

D. Circular shapes other than the above are due to the diversity of waves returning from the underwater target and the complex structures attached to it.

Note that these are the features of the idealized pattern.

FIG. 5 shows an example of the beam pattern (vertical plane) of the omnidirectional (omnidirectional) hydrophone 16, which is not uniform in all directions.

FIG. 6A shows the target strength of the aspect bow, FIG. 6B shows the target strength of the aspect aspect ratio, and FIG. 6C shows the target strength of the aspect around 225 degrees.

In the case of simulating the target strength of an underwater target or the like, it is generally impossible to simulate the target strength of the underwater target exemplified by FIG. 4 with the hydrophone 16. Therefore, the present invention outputs this as a function of change according to the aspect angle without simulating it all at once. For example, the response from the bow is shown in Figure 1.
Direction sensor 11 built into the acoustic simulation system shown in
6 to detect the aspect angle, and calculate the corresponding target strength by the digital computer 15 or as a search result from the data base 14 as shown in FIG.
The target strength 613 of the aspect bow 611 in (a) is output. The feature points in FIG. 6A are
Only the aspect planes are linked at the same level, and the characteristic 612 for the target strength aspect of the underwater target in the shaded area and the simulated characteristic 613 for the target strength aspect of the simulated target shown by a circle 613.
Is the difference. Further, as shown in FIG. 6B, the target strength in the vicinity of the aspect normal width 621 is also output by the same logic, and the simulated characteristic 623 for the aspect of the target strength of the underwater target in the shaded area is also the maximum circle. is doing. Further, in the target strength near the aspect of 225 degrees as shown in FIG. 6C, similarly, only the aspect surfaces near the aspect 225 of 631 are linked at the same level. When the circular simulated target strength is plotted over the entire circumference in this manner, the curve as a whole exhibits the characteristics of the delicate underwater target target strength as shown in FIG. The target strength of this underwater target shown in FIG. 4 is a plane, but is actually a solid. The target strength varies depending on the shape and structure of the underwater target, the hull material, the frequency, the depth, the distance, the pulse width, etc., and the target strength of the underwater target does not always have the butterfly pattern shown in FIG. . Therefore, FIG. 4 shows one sample, and it is necessary to calculate a butterfly pattern suitable for the characteristic by the digital computer 15 or retrieve it from the database 14 to simulate it.

If the beam pattern of the hydrophone 16 has distortion with respect to each aspect plane, the characteristic data thereof is corrected by the digital computer 15 which is input in advance.
This means that, for example, in FIG.
Even if the output of the target strength is set to 10 dB, if the hydrophone 16 itself is distorted, there may be a case where the output is only 9.5 dB at a certain aspect angle. In such a case, the aspect surface is the same. At that angle to link to 10.5d
Correct the output to B.

Next, the elongation of the target echo relating to the pulse and the aspect will be described with reference to FIG. 7 showing an embodiment.
FIG. 7 (a) is a diagram showing a relationship between an underwater target facing obliquely and an acoustic pulse corresponding to it, FIG. 7 (b) is a diagram showing a waveform of a reverberant sound, and FIG. 7 (c) is a convex / concave portion of the target. It is a figure explaining the relationship between and a reflection echo. 7 (a), (b),
AA ', BB', CC ', and DD' in (c) are symbols for explaining the extension of each hull portion of the pulse.
Here, as an example, the underwater target 7 facing diagonally
Considering the acoustic pulse 72, which corresponds to 1, pulse 7
2 is approaching the target from the bow. When the tip of the pulse 72 reaches point A, energy reflection begins. When the end of the pulse passes point A, the returning energy decreases (at which point the tip is at point A '). At point B, where there is a new wall for the pulse, the reverberant energy level increases again. After the end of the pulse passes point B,
Energy levels decrease. At that time, the tip of the pulse is at point B '. The energy level remains at this level until the end of the pulse passes point C. Then, when the tip of the pulse reaches point D, the energy of the reverberant sound drops and falls below ambient noise. Therefore, the total length of the returned echoes is the target length (a function of the target angle of attack (in the case of monostatic sonar, 2Lcosθ / c,
Where L = length of underwater target, θ = incident angle, c = sound velocity)) and pulse width.

In this way, the azimuth sensor 11 and the pulse sensor 12 shown in FIG. 1 calculate the elongation of the echo which changes according to the pulse width and the aspect as described above by the digital computer 15 or the retrieval result from the database 14. As a result, the reverberant sound waveform shown in FIG. Here the amplitude of the waveform is a function of the target strength. The length of the waveform will be the target depth plus the pulse width (as a function of apparent orientation). The points A and B of the reverberation sound waveform shown in FIG.
In (a), it is reflected from the points A and B of the underwater target facing diagonally. Reverberation waveform (Fig. 7
In (b), A to D indicate target depths. The energy is reflected from the time the tip of the pulse hits point D until the end of the pulse passes point D, so the area from D to D'is determined by the pulse length. Figure 7
The large amplitude portions of the waveforms between A and A ', B and B'in the reverberant sound in (b) are the pulses at points A and B (Fig. 7 (a)) of the underwater target facing diagonally. Is due to the reflection on the wall.

The target structure, which is related to resolution, can also be analyzed as a function of pulse width. The shorter the pulse, the shorter the distance between the target bumps (which changes the reflection intensity) that can be resolved. In order to resolve the target bumps, the pulse time must be shorter than the time required for the pulse tip to propagate from one bump to the next. The bumps and dips are shown as points where there are walls that change the pulse. If the pulse width is as shown in Fig. 7 (c)
If there is a point A to a point B, the reflection at the end point of the pulse is still continuing when the tip of the pulse reaches point B. Therefore, these two points overlap and point B cannot be identified (decomposed). The ruggedness can be disassembled, and FIG.
The maximum pulse width that can identify the target as shown in (c) is determined as follows. Figure 7 (c)
In, the distance between point A and the first important convex / concave point B is 10
It is 0 ft (about 30.48 m). Sound velocity is 5000ft
Assuming / sec, this distance is expressed in time.

T = d / c (5)

Where c: sound velocity (ft / sec),
d: distance propagated during time t (ft), t: time required for sound to propagate during distance d (second)

For the distance between points A and B,

T = d / c = 100 / (5 × 10 ³ ) = 20 ms

If the pulse width is longer than 20 ms, it is not possible to resolve the unevenness at the point B.

Such algorithm calculation is performed by the aspect angle data obtained from the azimuth sensor 11 in FIG. 1, the pulse width data obtained from the pulse sensor 12,
It is performed in the digital computer 15 based on the attitude angle data obtained from the gyro 13.

FIG. 8 is a diagram for explaining the embodiment of the Doppler, showing the relationship between the aspect and the Doppler. In FIG. 8, 81 is an aspect stern and the Doppler is low. Reference numeral 82 indicates an aspect horizontal direction, and the underwater target is moving to the left, but there is no Doppler. Similarly, the 83 is moving to the right with the aspect ratio horizontal, but there is no Doppler. The 84 is the aspect bow and has a high Doppler. Such Doppler is calculated in the digital computer 15 according to the aspect data obtained from the azimuth sensor 11 and the assumed speed or actual speed preset for the underwater target to be simulated. In a sonar having an ODN (self-doppler eliminator) (in FIG. 2, the underwater vehicle 21, the ship 22 on the water is mounted), detection of a Doppler such as an underwater target is performed.
The aspect is related to the opponent's underwater target Doppler.

The frequency of the echo from the moving underwater object or the like changes due to the so-called Doppler effect. The amount is given by the following equation.

Δf = 2 (v / c) · f

Where Δf = Doppler frequency (Hz) v = variation rate: Relative velocity (kt) between the sound source on the line of sight and the underwater target, etc. c = Sonic velocity (4800 ft / sec = 2900 kt) f = Sonar's Oscillation frequency (Hz)

Therefore, the above equation is as follows.

Δf = 2f · v / 2900

Therefore,

Δf = 0.69 · 10 ⁻³ · f · v

If f is expressed in kHz, it becomes even simpler.

Δf = ± 0.69f · v

It becomes Here, when the oscillation frequency of the echo of the underwater target or the like approaching the relative speed of 10 kn is 10 kHz, the frequency shifts to a frequency higher by 69 Hz. The ± sign is + when an echo is coming from an approaching underwater target, and − when it is moving away.

Although a simple calculation example has been shown above, the Doppler is calculated by such an algorithm.

In the above-described embodiment, the system using one hydrophone 16 is used.
Two or more mobile array towed sound simulation systems may be used.

FIG. 9 is a diagram showing a mobile array towed acoustic simulation system. In FIG. 9, reference numeral 91 is a towed vehicle, in which fuel and engine (battery and motor in the case of electric propulsion), autopilot, sensor (direction sensor 11, pulse sensor 12 in FIG. 1, etc.)
And a computer (digital computer 1 in FIG. 1
5), a low frequency transducer (corresponding to the hydrophone 16 in FIG. 1 for low frequency), a signal processing device (including an acoustic signal processing device 18, a transducer switching device 17 in FIG. 1), and the like. Mount. A towline 92 includes a signal cable. Reference numeral 63 is a responder for underwater vehicle of a plurality of towed arrays, and corresponds to the hydrophone 16 in FIG.

By towing a plurality of responders in this manner, the target strength and the length of the physical underwater target, the geometrical reality of the Doppler and the cruising distance are enabled, or all of the underwater objects and the like are realized. It is possible to correspond to the technology of hitting the underwater vehicle at an arbitrary position from the sound reflected from the rear and the target identification technology.Moreover, it is possible to use multiple transducers that match the characteristics of the frequency. The target acoustic simulation system of a simple sonar can be realized.

[0070]

As described in detail above, according to the present invention, the output corresponding to the pulse width can be finely simulated by the computer's arithmetic function with the aspect angle with a simple system. Therefore, this system can be used practically and highly as a target system for underwater vehicles and sonars, and as a test system for underwater vehicles and sonars.

A homing system for an underwater vehicle for an underwater target or the like generates a target acoustic simulation system for active sonar, for example, a Doppler with a strong aspect bow and a strong target strength with a wide ship aspect, and a target echo extension. It enables detection and gate (detection) from a long distance. On the one hand, this can be used as a system to protect oneself from underwater vehicles approaching underwater targets and the like. Further, the target strength not only indicates the existence of the target but also leads to the target identification by the pattern recognition of the target strength. Therefore, if there is a system for identifying the target strength, it is possible to test and take measures to what extent it is. The system does not have to consider difficult ray paths and ambient noise.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a target acoustic simulation system for active sonar of the present invention.

FIG. 2 is a diagram for explaining a target acoustic simulation system for an active sonar used as a conventional stationary target.

FIG. 3 is a diagram illustrating a target strength of a simulated sound signature.

FIG. 4 is a diagram showing characteristics of an underwater target with respect to target strength and aspect.

FIG. 5 is a diagram showing an example of a beam pattern (vertical plane) of a hydrophone.

FIG. 6 is a diagram illustrating target strength according to the embodiment of this invention.

FIG. 7 is a diagram for explaining expansion of a target echo.

FIG. 8 is a diagram illustrating an example of a Doppler.

FIG. 9 is a diagram showing a mobile array towed acoustic simulation system.

[Explanation of symbols]

 11 Direction Sensor 12 Pulse Sensor 13 Gyro 14 Data Base 15 Digital Computer 16 Hydrophone 17 Transducer Switch 18 Acoustic Signal Processing Device 19 External Storage Device

Claims (9)

[Claims] 1. An azimuth sensor for detecting the direction of arrival of a pulse propagating in water, a calculation means for calculating a target strength to be simulated according to the detection direction of the azimuth sensor, and a target calculated by the calculation means.・
A target sound simulation system for an active sonar, comprising: a sound conversion unit that outputs a simulation sound according to strength. 2. An azimuth sensor for detecting the arrival direction of a pulse propagating in water, a pulse sensor for detecting the arrival pulse width, and a target strength to be simulated according to the detection direction of the azimuth sensor. ,
A calculating means for calculating the elongation of the target echo according to the arrival direction of the pulse and the pulse width, and an acoustic converting means for outputting a simulated sound according to the elongation of the target strength and the target echo calculated by the calculating means. A target acoustic simulation system for active sonar, which is equipped with. 3. An azimuth sensor for detecting an arrival direction of a pulse propagating in water, a pulse sensor for detecting an arrival pulse width, a target strength to be simulated according to the detection direction of the azimuth sensor, and a pulse Calculating the elongation of the target echo according to the direction of arrival and the pulse width, and calculating means for calculating the Doppler according to the preset speed and the detection direction of the direction sensor, and the target strength calculated by the calculating means. And a target sound simulation system for an active sonar, comprising: a sound conversion unit that outputs a simulation sound corresponding to Doppler along with the expansion of the target echo. 4. An angle detecting means for detecting the attitude angle of the self is provided, and the calculating means corrects the change angle detected by the angle detecting means with respect to the detection direction of the azimuth sensor to obtain the target strength and the target echo. The target acoustic simulation system for an active sonar according to any one of claims 1 to 3, wherein elongation and Doppler are calculated. 5. A data base having simulated acoustic data according to the arrival direction of the pulse and the pulse width is provided, and the calculation means calculates the data according to the arrival direction and the pulse width of the pulse.
The target acoustic simulation system for active sonar according to any one of claims 1 to 4, wherein a base is searched. 6. The sound quality of the simulated sound calculated by the calculation means is a metal sound reflection sound quality or a reflection sound quality in which a metal hull surface is equipped with sound insulation tiles. Target sound simulation system for active sonar. 7. The value of the transmission level with respect to the aspect is corrected by the calculation means so that the direction characteristic of the acoustic conversion means is omnidirectional in the hydrophone so that even if the output is distorted, it becomes uniform in all directions. The target sound simulation system for an active sonar according to any one of claims 1 to 5. 8. An external storage means for storing the detection direction of the azimuth sensor, the pulse width of the pulse sensor, the attitude angle data of the angle detection means, and the output data calculated by the calculation means or the searched search data. The target sound simulation system for an active sonar according to any one of claims 1 to 7. 9. The target acoustic simulation system for an active sonar according to claim 1, wherein the plurality of acoustic conversion means are mounted on an array towed by a movable casing.