JP2913568B2 - Sound target simulation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic target simulator for acoustically simulating an active sonar target.

[0002]

2. Description of the Related Art Conventionally, as a device for acoustically simulating a target of an active sonar, there is a device in which a plurality of so-called echo repeaters for directly transmitting a received active pulse sound are arranged in a linear array. FIG. 4 is an explanatory view showing the arrangement and configuration of a conventional acoustic target simulation device. (A) of FIG. 2 shows units # 1 to #N 9-N each having a built-in echo repeater arranged in a linear array at predetermined intervals.
Each of them is connected by a towing cable and is towed in water. FIG. 4B is a block diagram showing the configuration of a conventional echo repeater unit. Each echo repeater unit 9-i (i = 1, 2,... N) includes a receiver 1, a signal detector 2, Signal feature extraction unit 3, signal reconstruction unit 4
And a transmitter 5.

FIG. 5 is a diagram showing the positional relationship between the direction of the linear array in FIG. 4 and the acoustic wavefront, and FIG. 6 is a waveform diagram showing the process of generating a pseudo echo by the conventional device.

The operation of FIG. 4 will be described with reference to FIGS. The active pulse sound arriving from an arbitrary direction in the water is output from each echo repeater unit 9-i (i = 1, 2, 2).
.. N), and the active pulse sound is detected by the signal detection unit 2. From the detected active pulse sound, the characteristics of the pulse sound such as the center frequency, amplitude, and pulse width of the pulse sound are extracted by the signal characteristic extraction unit 3 in the next stage. Then, based on the extracted features, the next-stage signal reconstructing unit 4 reconstructs pulse signals having the same features, and transmits them from the transmitter 5 as pseudo echoes.

When the active pulse sound is received, N echo repeater units 9-i (i = 1, 2,... N) for individually transmitting the pseudo echo signals are spatially distributed. Therefore, when an active pulse sound is applied to the acoustic simulation apparatus, a pseudo echo similar to the echo obtained when the active pulse sound is applied to a real target is obtained. For example, as shown in FIG. 5, when a sound wave enters the acoustic target simulation device from an oblique direction, a multi-echo based on the propagation path difference is generated.

[0006] In FIG. 5, the wavefront X of the incident wave S is based on the time _{t X} that has reached the # 1 echo repeater unit 9-1, within the unit 9-1 from the # 1 echo repeater unit 9-1 A pseudo echo R ₁ is generated with a delay of the processing time τ ₀ . (See (a) and (b) of FIG. 6). # Reception time of the signal propagating from the second echo repeater unit 9-2 wavefront X is delayed the t _X than by the time tau _2, echo replica R ₂ generated by the unit 9-2
There is transmitting to reach the position of the wavefront X that the reference is made to the time delayed from the t _X by 2τ _{2 +} τ ₀ (see (c) of FIG. 6). Similarly #N Echo Repeater Unit 9-N pseudo generated by echo R _N has reached the position of the transmitting wavefront X will time delayed from t _X only 2τ _{N +} τ ₀ (in FIG. 6 ( d)).

The # 1 to #N eco-repeater units 9-
1 to 9-N echo replica R ₁ ~ produced respectively by
R _N The synthesis pseudo echo received at a sufficiently distant R (see (e) in FIG. 6) is similar to the real echoes from the structure each having a sound scattering points to generate the position of each pseudo echo.
Therefore, a plurality of echo repeater units arranged in a linear array will operate as an acoustic target simulator as a whole.

[0008]

However, in the conventional acoustic target simulation apparatus as described above, when the incident direction of the active pulse sound changes, the time interval between the generated pseudo echoes changes according to the direction change. Although it is possible to simulate by following the change, the amplitude of each pseudo echo is always constant, and the pseudo echo is composed of N equal amplitude components. In particular, when the incident direction of the active pulse sound is in front of or behind the linear array, in the actual structure, only the echo from the tip of the structure from which the sound wave arrives is dominant, and the echo from other parts is dominant. Since almost no noise occurs, there is a problem that a real echo is greatly different from a simulated echo simulating this.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. Not only does the time interval between generated pseudo echoes change depending on the arrival direction of the active pulse sound, but also each pseudo echo It is an object of the present invention to obtain an acoustic target simulation apparatus capable of generating a pseudo echo very similar to a real echo by varying the amplitude of the target.

[0010]

An acoustic target simulation apparatus according to the present invention comprises a plurality of echo repeaters arranged in a linear array, wherein each of the plurality of echo repeaters has an arbitrary direction in water. An acoustic target simulation apparatus for receiving an active pulse sound arriving from a received signal, amplifying a pulse signal reconstructed based on the features extracted from the received signal, and transmitting the amplified signal as a sound wave. At least two receivers respectively provided at predetermined positions in the array arrangement and receiving the active pulse sound, and a difference between reception times of the active pulse sounds received by the respective receivers is determined based on a difference between reception times of the active pulse sounds. Direction detecting means comprising a direction calculator for calculating the direction of arrival; and A storage unit for storing a transmission coefficient weight coefficient for each of the echo repeaters; and a transmission amplitude weight for each of the plurality of echo repeaters read from the storage unit based on the arrival direction of the active pulse sound detected by the direction detection unit. Amplitude control means comprising an amplitude controller for supplying an amplitude control signal based on a coefficient to each of the plurality of echo repeaters, and an amplitude control means built in each of the plurality of echo repeaters,
A pulse signal reconstructed based on a feature extracted from a received signal in each echo repeater, for each of the plurality of echo repeaters, each of which amplifies with a variable gain by an amplitude control signal supplied from the amplitude control means. And a variable gain amplifier.

[0011]

According to the present invention, a plurality of echo repeaters are arranged in a linear array, and each of the plurality of echo repeaters receives an active pulse sound arriving from an arbitrary direction in water. In an acoustic target simulation apparatus for amplifying a pulse signal reconstructed based on a feature extracted from a received signal and transmitting the amplified signal as a sound wave, a direction detecting unit is provided at a predetermined position in the linear array. At least two receivers and a direction calculator are provided, each of the receivers receiving the active pulse sound, and the direction calculator is configured to receive the active pulse sound received by the receiver respectively. The arrival direction of the active pulse sound is calculated from the difference between the reception times. The amplitude control means includes a storage device and an amplitude controller, wherein the storage device stores in advance a weighting coefficient of a transmission amplitude for each of the plurality of echo repeaters corresponding to each direction in which the active pulse sound arrives, and The controller controls the plurality of echo repeaters corresponding to the amplitude control signals based on the transmission coefficient weighting coefficient for each of the plurality of echo repeaters read out from the storage device based on the arrival direction of the active pulse sound detected by the direction detection means. To supply. Each of the plurality of echo repeaters has a built-in variable gain amplifier for controlling the transmission amplitude,
Each of the variable gain amplifiers amplifies a pulse signal reconstructed based on a feature extracted from a received signal in each echo repeater with a variable gain according to an amplitude control signal supplied from the amplitude control means.

[0012]

FIG. 1 is a block diagram showing the configuration of an acoustic target simulation apparatus according to the present invention, and FIG. 2 is an explanatory diagram showing the arrangement of the acoustic target simulator of FIG. In FIG. 2, the leading # 1 receiver 10-1 to the trailing # 3 receiver 10- connected respectively by the towing cable.
Each device up to 3 is originally arranged in a linear array, but is drawn in a folded state because it cannot be drawn as a straight line due to lack of space.

In FIGS. 1 and 2, 10-1 and 10-
Reference numerals 2 and 10-3 denote # 1, # 2 and # 3 receivers, respectively, as N acoustic control echo repeater units 8-1 shown in FIG. 2 as acoustic sensors for detecting the arrival direction of the active pulse sound. ... 8-N are arranged at the beginning, the center and the end, respectively. Reference numeral 11 denotes a direction detection and amplitude control unit, in which a direction calculator 1 is provided.
2, an amplitude weighting coefficient memory 13 and an amplitude controller 14 are included. The direction detection and amplitude control unit 11 is arranged substantially at the center of the linear array configuration as in the example of FIG.

The operation of FIG. 1 will be described with reference to FIG. As shown in FIG. 2, # 1 to # 3 receivers 10-1 to 10- arranged at the head, center, and end of the linear array, respectively.
The active pulse signals respectively received by 3 are:
It is input to a direction calculator 12 in the direction detection and amplitude controller 11. The direction calculator 12 includes # 1 to # 3 receivers 10-1 to 10-1.
10-3 detects the difference (i.e., time) between the reception times of the received active pulse sounds, and calculates the arrival direction of the active pulse sound from the difference time.

As a method of calculating the arrival direction of the sound wave, for example, when the hyperbolic method is used, the # 1 receiver 10-1 and the # 2 receiver 1
The difference τ _{12 in} the reception time between 0-2 and the # 2 receiver 10−
By detecting the difference τ ₂₃ in the reception time between the receiver 2 and the # 3 receiver 10-3, the arrival direction θ of the sound wave can be calculated by the following approximate expression (1).

(Equation 1) In the formula (1), C is sound _{velocity, d 12} is # 1 receivers 10
-1 and # distance between 2 receivers _{10-2, d 23} is the distance between the # 2 receivers 10-2 and # 3 receivers 10-3. Θ is an angle obtained by measuring the direction of arrival of a sound wave from the reference direction using the normal direction of the linear array as the reference direction.

As a simple calculation method of the arrival direction θ of the sound wave, the following equation (2) is obtained from the difference τ between the reception times of the two receivers.
There is also a method of calculating using.

(Equation 2) In equation (2), C is the speed of sound, and d is the distance between the two receivers.

The data of the azimuth of arrival of the active pulse sound calculated by the direction calculator 12 according to the calculation formula (1) or (2) is used as address reference data for reading data from the amplitude weighting coefficient memory 13 as an amplitude controller. 14 is sent. The address reference data designates, for example, when the amplitude controller 14 sequentially reads out N data corresponding to the arrival direction of the sound wave, specifies the head address of an address area in which the N data is stored. Data.

The amplitude weighting coefficient memory 13 is constituted by, for example, a read only memory (ROM) and is given to each amplitude control echo repeater unit 8i (i = 1, 2,... N) in advance corresponding to each direction of arrival of the sound wave. The data of the amplitude weighting factors is stored in, for example, a table format. The weighting coefficient data for each amplitude control echo repeater corresponding to each azimuth stored in the amplitude weighting coefficient memory 13 is obtained by measuring a real echo from a real target which the present apparatus is trying to simulate, or by using a numerical value for a pseudo model. It is set based on the result of the azimuth distribution of the scattering intensity obtained by performing the simulation, and is set in advance in the memory 1
3 are stored.

The amplitude controller 14 stores N amplitude weighting coefficient data corresponding to the arrival direction of the active pulse sound based on the address reference data (for example, the head address data) supplied from the azimuth calculator 12 in an amplitude weighting coefficient memory. 1
3 are sequentially read out, and the read weight coefficient data are respectively converted into analog voltage amplitude control signals via D / A converters as # 1 to #N amplitude control echo repeater units 8-1 to 8-N. To supply. In the above example, an example in which the amplitude control signal is supplied as an analog voltage signal has been described. However, digital data is supplied as it is to each amplitude control echo repeater unit 8i (i = 1, 2,... N). The required conversion processing may be performed within 8i.

FIG. 3 is a block diagram of the amplitude control echo repeater unit according to the present invention, wherein 1 to 5 are the same devices as in FIG. 6 in the figure is a variable gain amplifier.
Is an input terminal for supplying an externally input amplitude control signal to the variable gain amplifier 6.

Each amplitude control echo repeater unit 8i (i
= 1, 2,... N), the active pulse sound is received by the receiver 1, and then has the same characteristics as the received signal via the signal detector 2, the signal feature extractor 3, and the signal reconstructor 4. Until the pseudo echo signal is reconstructed, the same operation as in FIG. 4 is performed. Next, the variable gain amplifier 6 is connected to the amplitude controller 1 in the direction detection and amplitude controller 11.
4 amplifies the output signal of the signal reconstructing unit 4 with a gain (generally referred to as a gain) determined by the amplitude control signal for each amplitude control echo repeater unit supplied via the input terminal 7 from the transmitter 4. To send to. The transmitter 5 is driven by the output of the variable gain amplifier 6, and transmits a sound wave having an amplitude proportional to the driving voltage.

As described above, according to the incident direction of the active pulse sound, the N amplitude-controlled echo repeater units 8i (i = 1, 2,..., N) transmit amplitude-controlled pseudo echoes, respectively. Since the waves are waved and the time interval between the pseudo echoes also changes at the same time, a composite wave that receives these pseudo echoes at a sufficiently long distance becomes a simulated echo that is very similar to the echo from the actual structure.

[0023]

As described above, according to the present invention, a plurality of echo repeaters are arranged in a linear array, and each of the plurality of echo repeaters has an active pulse coming from an arbitrary direction in the water. Receive the sound,
In the acoustic target simulation device that amplifies the pulse signal reconstructed based on the feature extracted from the received signal and transmits the amplified signal as a sound wave, at least a predetermined position of the linear array is provided. The direction of arrival of the active pulse sound is detected by a direction detecting means comprising two receivers and a direction calculator, and the transmission amplitude of the plurality of echo repeaters for each of the plurality of echo repeaters is detected corresponding to each direction in which the active pulse sound arrives. Amplitude control means comprising a memory for storing a weighting coefficient and an amplitude controller outputs an amplitude control signal for each of the plurality of echo repeaters in accordance with the arrival direction of the active pulse sound. The variable gain amplifier built in the echo repeater converts the pulse signal reconstructed based on the features extracted from the received signal in each echo repeater, Since the transmission amplitude of each echo repeater is controlled by amplifying each variable gain by the amplitude control signal output from the amplitude control means, the time between the pseudo echoes changes when the incident direction of the active pulse sound changes. Since the amplitude of each pseudo echo changes as the interval changes, a simulated echo very similar to the echo from the actual structure can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an acoustic target simulation device according to the present invention.

FIG. 2 is an explanatory view showing an arrangement of the acoustic target simulation apparatus of FIG. 1;

FIG. 3 is a block diagram of an amplitude control echo repeater unit according to the present invention.

FIG. 4 is an explanatory diagram showing the arrangement and configuration of a conventional acoustic target simulation device.

FIG. 5 is a diagram showing a positional relationship between the direction of the linear array in FIG. 4 and an acoustic wavefront.

FIG. 6 is a waveform diagram showing a process of generating a pseudo echo by a conventional device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 receiver 2 signal detector 3 signal feature extractor 4 signal reconstructor 5 transmitter 6 variable gain amplifier 7 input terminal 8-1 to 8 -N # 1 to #N amplitude control echo repeater unit 9-1 9-N # 1 to #N echo repeater unit 10-1 to 10-3 # 1 to # 3 receiver 11 Direction detection and amplitude control unit 12 Direction operation unit 13 Amplitude weight coefficient memory 14 Amplitude controller

Continuation of the front page (56) References JP-A-59-160782 (JP, A) JP-A-57-173772 (JP, A) JP-A-61-181985 (JP, A) JP-A-54-68273 (JP, A) JP-A-60-183572 (JP, A) JP-A-61-231398 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01S 7/52 G01S 3/801

Claims (1)

(57) [Claims] 1. A plurality of echo repeaters each comprising a plurality of echo repeaters arranged in a linear array.
, Respectively, activities coming from any direction in the water
Received a pulse sound and based on features extracted from the received signal.
And amplify the reconstructed pulse signal.
In the acoustic target simulation device transmitting as a sound wave, provided at predetermined positions of the linear array arrangement ,
At least two receivers each receiving the active pulse sound, and a direction calculator for calculating an arrival direction of the active pulse sound from a difference between reception times of the active pulse sounds respectively received by the receivers. and direction detecting means, advance a storage unit for storing the weighting coefficients of transmit amplitude of each of the plurality of echo repeater corresponding to each orientation for the arrival of the active pulse sound arrival of active pulse sound the direction detecting means detects Read from the memory by direction
A plurality of groups to the weight coefficient for transmitting the amplitude of each echo repeater Dzu was
An amplitude control means consisting of a Ku amplitude control signal, respectively corresponding to supply amplitude controller to each of the plurality of echo repeater is built into each of the plurality of echo repeater, respective Ekori
Reconstructed in Peter based on features extracted from the received signal
The pulse signal, said that each amplified by the variable gain by the amplitude control signal supplied from each of said amplitude control means
An acoustic target simulation device comprising: a plurality of variable gain amplifiers for each echo repeater .