JP2002350538A - Target identifier of sonar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a target identifier of a sonar which is capable of identifying a true target from false targets for a short time, without changing the angle of a linear array receiver. SOLUTION: The identifier comprises a transmitter 1 for transmitting different signals to a true target and false targets, a receiver 4 for receiving echo signals reflected from the true target 2, respectively, a correlation processor 5 for processing the correlation of signals from the receiver 4, respectively, to obtain correlation outputs, based on the radiated signals and a true-false target identifier 6 for mutually comparing the correlation outputs obtained from the processor 5 to identify the true target 2 from the false targets 3 from the result thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sonar target identification device provided with a linear array receiver, and more particularly to a sonar target identification device which emits an acoustic pulse wave from a transmitter to identify the presence or absence of a target. It concerns the device.

[0002]

2. Description of the Related Art An active sonar in which a transmitter and a receiver are arranged at the same position as a sonar system for receiving an acoustic wave from a target object of an acoustic pulse wave radiated from a transmitter by a receiver. A typical example is a bistatic sonar in which a transmitter and a receiver are arranged at different positions.

As shown in FIG. 4, the active sonar emits an acoustic pulse wave 44 from a transmitter 42, receives a reverberation sound 45 from a target 41, and a receiver 43 receives the echo 45 from the target. This is a sonar system that detects the presence of 41 and estimates the position of the target 41. The presence of the target 41 is detected by “presence or absence of reverberation 45”, and the position (azimuth) of the target 41 is detected.
Is estimated from the “arrival direction of the reverberation sound 45”, and the position (distance) of the target 41 is “
5 required time until reception ".

In a bistatic sonar, when the receivers are arranged in a straight line, the beam of the receiver has a main pole on a cone with the receiver array as an axis. Detection is made as two targets in azimuths symmetrical to the direction. For example, as shown in FIG. 5, the acoustic pulse wave 55 radiated from the transmitter 51
And is received by the linear array receiver 52 as reverberation sound 56 and detected as the target azimuth (+ A). on the other hand,
The acoustic pulse wave 57 radiated from the transmitter 51 reflects the imaginary target 54 and is received in the linear array receiver 52 as the reverberation sound 58 from the imaginary target 54 in the (−A) direction. It is detected as if there is a target at the corner.

The time required for the acoustic pulse wave 55 from the transmitter 51 to be reflected by the real target 53 and received by the linear array receiver 52 and the acoustic pulse wave 57 from the transmitter 51 to be the imaginary target The time from the reflection of the object 54 to the reception by the linear array receiver 52 is the same, and the propagation distance (propagation time) between the two points of the transmitter 51 and the linear array receiver 52 is equal. Is
An elliptical shape centered on two points of the transmitter 51 and the linear array receiver 52 is provided.

These two real targets 53 and imaginary targets 54
Cannot identify which is a true target as it is. So, to avoid this,
The true target is identified by a method in which the arrangement direction of the linear array receiver 52 is slightly changed so that the receiving direction from the target is changed.

For example, as shown in FIG. 6, when the linear array receiver 52 is inclined at an angle B, the azimuth of the real target 53 received by the linear array receiver 52 is (+ C), and the imaginary target is received. The azimuth of the object 54 is detected as (-C).

[0008] When the angle change when the direction of the linear array receiver 52 is changed with respect to the azimuth angle of the two targets is obtained, a real target AC = B an imaginary target-A- (B -C) =-(AC) -B = -2
B, the change of the real target 53 is the change (B) of the receiver 52, but the change of the imaginary target 54 is twice the change (B) of the receiver 52. As a result, the real target 53 and the imaginary target 54 can be identified.

[0009]

In the above-mentioned conventional bistatic sonar, the angle of the linear array receiver 52 is inclined in order to distinguish between the real target 53 and the imaginary target 54. In some cases, the detection capability of processing or the like is reduced, and the detected target may be lost.

In the towed sonar, since the linear array receiver 52 is towed, even if the course of the ship is changed,
There is a time delay due to the change in the depth of the linear array receiver 52 and the followability of the azimuth, and it takes time until the state of the linear array receiver 52 becomes stable, and it takes time to detect again.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and can identify a real target and an imaginary target in a short time without changing the angle of a linear array receiver, and can determine the position of a true target. It is an object of the present invention to provide a sonar target identification device capable of estimating the sonar target.

[0012]

A sonar target identification apparatus according to the present invention comprises a signal generator for generating at least two types of signals, and a transmitter for radiating signals from the signal generators in at least two directions. And a receiver for receiving a reflected signal of the radiation signal from the target, and a correlation process for performing a correlation process on the signal from the receiver based on each signal of the signal generation unit to obtain a correlation output And a real / imaginary target discriminating unit for comparing the correlation outputs obtained by the correlation processing unit with each other and discriminating a real target and an imaginary target from the result.

In the present invention, as shown in FIG. 1, for example, when different signals are radiated from the transmitter 1 to the real target side and the imaginary target side, the signal reaching the real target 2 is reflected. The signal radiated to the imaginary target side attenuates without reflecting the imaginary target 3. At this time, the receiver 4 receives the reflected signal of the radiation signal from the target, and outputs the signal to the correlation processing unit 5.
Performs a correlation process on the signal from the receiver 4 based on the signal radiated to the real target 2 and the signal radiated to the imaginary target 3 to obtain a correlation output. The real / imaginary target discriminating unit 6 compares the respective correlation outputs obtained by the correlation processing unit 5 with each other.
Identify.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 2 is a block diagram of a sonar target identifying apparatus according to Embodiment 1 of the present invention. In the figure, reference numeral 21a denotes an UP signal generator (first signal generator) for generating an UP signal (first signal), 2
1b is a DOWN signal generator (second signal generator) for generating a DOWN signal (second signal). The above-mentioned UP signal has a transmission instantaneous frequency of f1 to f
LF linearly increasing with time up to 2 (f1 <f2)
M (LinearFM) pulse signal, and DOW
The N signal has an instantaneous transmission frequency f2 to f
LF linearly decreasing with time until 1 (f1 <f2)
M pulse signal.

Reference numeral 22a denotes an UP signal from the UP signal generator 21a.
An UP signal amplifier for amplifying the signal, 22b is a DOWN signal amplifier for amplifying the DOWN signal from the DOWN signal generator 21b, and 23a is an UP signal transmitter (first transmitter) for emitting an acoustic pulse wave based on the UP signal into the sea. Device 23b emits an acoustic pulse wave based on the DOWN signal into the sea.
It is an OWN signal transmitter (second transmitter). The UP signal transmitter 23a and the DOWN signal transmitter 23b are provided, for example, on the bottom of the ship, and are respectively directed at directions of predetermined angles about the axis of the ship when viewed in plan.

Reference numeral 24 denotes a linearly arranged receiver for receiving, for example, a reverberation sound reflected from a real target in the sea, which is towed by a ship, and converting it into an electric signal. An UP signal correlation processor (first correlation processor) 25b for performing a correlation process using the set UP signal as a replica, 25b is a DOWN preset for the signal from the receiver 24.
This is a DOWN signal correlation processor (second correlation processor) that performs correlation processing using a signal as a replica.

Reference numeral 26 denotes a real / imaginary target discriminator, which compares the correlation output from the UP signal correlation processor 25a with the correlation output from the DOWN signal correlation processor 25b. Identify things. For example, when the correlation output of the UP signal correlation processor 25a is large, it is determined that an actual target exists on the UP signal transmitter 23a side, and conversely, DOWN
DOW when the correlation output of the signal correlation processor 25b is large
It is determined that an actual target exists on the N signal transmitter side.

Next, the operation of the first embodiment will be described with reference to FIG. For convenience of explanation of the operation, an UP signal is emitted to the real target and a DOWN signal is emitted to the imaginary target. When the UP signal generator 21a emits an UP signal and the DOWN signal generator 21b emits a DOWN signal, the UP signal amplifier 22a amplifies the UP signal, and the UP signal transmitter 23a outputs an acoustic pulse based on the UP signal. Radiates waves into the sea, while DOWN signal amplifier 2
2b amplifies the DOWN signal from the DOWN signal generator 21b, and the DOWN signal transmitter 23b radiates an acoustic pulse wave based on the DOWN signal into the sea. At this time, UP
The acoustic pulse wave radiated from the signal transmitter 23a reflects the actual target, and travels toward the linearly arranged receiver 24 as a reverberation sound, while the acoustic pulse wave radiated from the DOWN signal transmitter 23b is Since the imaginary target has no entity, it attenuates without being reflected.

The receiver 24 receives the reverberation sound reflected from the actual target, converts it into an electric signal, and sends it to the UP signal correlation processor 25a and the DOWN signal correlation processor 25b. The UP signal correlation processor 25a performs a correlation process on the signal from the receiver 24 using the preset UP signal as a replica, and sends the correlation output to the real / imaginary target discriminator 26. The DOWN signal correlation processor 25b includes:
DOWN set in advance for the signal from the receiver 24
A correlation process is performed using the signal as a replica, and the correlation output is sent to the real / imaginary target discriminator 26. In the DOWN signal correlation processor 25b, as described above, DOWN
Since the N signal is used as a replica, a small correlation output is obtained.

The real / imaginary target discriminator 26 compares the mutual correlation outputs obtained by the UP signal correlation processor 25a and the DOWN signal correlation processor 25b. In this case, since the correlation output on the UP signal correlation processor 25a side is large, it is recognized that a real target exists, and since the DOWN signal correlation processor 25b side is small, it is determined to be an imaginary target.

As described above, according to the first embodiment, the UP signal whose instantaneous frequency rises with time and the DOWN signal whose instantaneous frequency falls with time are radiated, respectively, and the UP signal and DOWN signal are respectively received with respect to the received signal. A correlation process is performed with the signal as a replica, and when the correlation output is large, it is judged as a real target, and when the correlation output is small, it is recognized as an imaginary target. There is an effect that a real target and an imaginary target can be distinguished in a short time without changing the direction of the target 24.

In the first embodiment, the acoustic pulse waves radiated from each of the transmitters 23a and 23b are exemplified as signals whose frequency simply rises or falls. It is also possible to linearly increase and then decrease linearly, and then decrease the other frequency linearly and then increase linearly. Alternatively, two types of acoustic pulse waves whose instantaneous frequency is changed in a non-linear (function) manner may be emitted from each of the transmitters 23a and 23b.

Embodiment 2 FIG. FIG. 3 is a block diagram showing a sonar target identifying apparatus according to a second embodiment of the present invention. In the figure, 31a is a first signal generator for generating a predetermined first signal, 32a is a first amplifier for amplifying the first signal from the first signal generator 31a, and 33a is a first amplifier 32
A first transmitter that emits an acoustic pulse wave based on the first signal amplified by a into the sea. 31b is a second signal generator for generating the same signal as the first signal as a second signal, 32b is a second amplifier for amplifying the second signal from the second signal generator 31b, and 33b is amplified by the second amplifier 32b. A second transmitter that radiates an acoustic pulse wave based on the obtained second signal into the sea.

The first and second signal generators 31a, 31a,
31b is configured to generate signals alternately,
For example, when the first signal generator 31a emits a first signal,
The second signal generator 31b emits a second signal after a predetermined time,
This is repeated alternately. The first and second transmitters 33
Similar to the first embodiment, a and 33b are provided at, for example, the bottom of a ship, and are respectively oriented in directions of a predetermined angle about the axis of the ship when viewed in plan.

Numeral 34 denotes a linearly arranged receiver for converting to an electric signal based on the reverberation sound reflected by a real target object in the sea, which is towed by a ship, and 35 denotes a phase adjuster. The phase lag of the signal based on the echo sound of the acoustic pulse wave radiated from the second transmitter 33b is adjusted (in-phase) and output as a phased beam.

Reference numeral 36a denotes a first energy detector for detecting acoustic energy (for example, voltage) from a reverberation sound to the first transmitter 33a, and 36b denotes a second energy for detecting acoustic energy from a reverberation sound to the second transmitter 33b. It is a detector. Reference numeral 37 denotes a real / imaginary target object discriminator. When sound energy detected by the first energy detector 36a is input, the sound energy is held, and sound energy detected by the second energy detector 36b is input. Is compared with the acoustic energy of the first energy detector 36a, and when the acoustic energy of the first energy detector 36a is large, it is determined that the actual target exists on the first transmitter 33a side. When the acoustic energy on the second energy detector 36b side is large, the second transmitter 3
It is determined that the actual target exists on the 3b side.

Next, the operation of the second embodiment will be described with reference to FIG. For convenience of explanation of the operation, it is assumed that there is no real target on the first transmitter 33a side and no imaginary target on the second transmitter 33b side. First, the first signal generator 31a generates a first signal, and after a predetermined time, the second signal generator 31b generates a second signal identical to the signal. The first signal from the first signal generator 31a is amplified by the first amplifier 32a, and the first transmitter 32a converts the signal into an acoustic pulse wave based on the signal and radiates it into the sea. This acoustic pulse wave is reflected on the actual target and reaches the receiver 34 as a reverberation sound.

At this time, the receiver 34 converts the reverberation sound into an electric signal and outputs it to the phase adjuster 35. The phase adjuster 35 adjusts the phase delay of the input electric signal (in-phase) and outputs the same to the first energy detector 36a as a phase-adjusted beam. The first energy detector 36a detects acoustic energy from within the phasing beam and outputs it to the real / imaginary target discriminator 37. At this time, the real / imaginary target discriminator 37 holds the acoustic energy.

On the other hand, the acoustic pulse wave radiated from the second transmitter 33b after a predetermined time is attenuated without being reflected because the imaginary target object does not have a substance. At this time, the phase delay of the electric signal is adjusted (in-phase) by inputting only sound such as noise to the receiver 34, and output to the second energy detector 36b as a phasing beam. Is detected. When the sound energy is input, the real / imaginary target object discriminator 37 compares the sound energy with the held sound energy. In this case, the first energy detector 36
Since the acoustic energy on the a side is large, it is determined that a real target exists on the first transmitter 33a side, and it is determined that the real target is on the second transmitter 33b side.

As described above, in the second embodiment, the same acoustic pulse wave is radiated to the real target and the imaginary target with a time difference, the acoustic energy in the reverberation is detected, and each energy is increased or decreased. The direction in which the real target exists or the imaginary target can be determined from the relationship, so that the direction of the linear arrayed receiver 34 is not changed and the real target can be determined in a short time. There is an effect that the imaginary target can be identified.

[0031]

As described above, according to the present invention, at least two types of signals are radiated from the transmitter, and the received signal is subjected to correlation processing based on each signal of the signal generator, and the correlation output is output. And the correlation outputs are compared with each other to discriminate the real target and the imaginary target from the result, so that the real target and the real target can be quickly changed without changing the direction of the receiver. There is an effect that the imaginary target can be identified.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the present invention.

FIG. 2 is a block diagram of a sonar target identifying apparatus according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a target identification device for a sonar according to a second embodiment of the present invention.

FIG. 4 is a conceptual diagram of operation of a conventional active sonar.

FIG. 5 is an explanatory diagram of a target search by a conventional bistatic sonar linear array receiver.

FIG. 6 is an explanatory diagram of a target search by changing the direction of a linear array receiver.

[Explanation of symbols]

21a UP signal generator, 21b DOWN signal generator, 22a UP signal amplifier, 22b DOWN signal amplifier, 23a UP signal transmitter, 23b DOWN signal transmitter, 24 receiver, 25a UP signal correlator,
25b DOWN signal correlator, 26 real / imaginary target discriminator, 31a first signal generator, 31b second signal generator, 32a first amplifier, 32b second amplifier, 33
a first transmitter, 33b second transmitter, 34 receiver,
35 phase adjuster, 36a first energy detector, 36b
Second energy detector, 37 real / imaginary target discriminator.

Claims (4)

[Claims] 1. A signal generator for generating at least two types of signals, a transmitter for radiating a signal from the signal generator in at least two directions, and a receiver for receiving a reflected signal of a radiation signal from a target. A correlator, a correlator for performing a correlation process on the signal from the receiver on the basis of each signal of the signal generator to obtain a correlated output, and a correlator obtained by the correlator. A sonar target identification device, comprising: a real / imaginary target identification unit that compares outputs with each other and identifies a real target and an imaginary target from the result. 2. A first signal generator for generating a first signal having a frequency sequentially increasing within a predetermined time, and a second signal generating for generating a second signal having a frequency sequentially decreasing within a predetermined time. A first device that emits an acoustic signal based on the first signal, the transmission direction being inclined at a predetermined angle with respect to the axis of the ship when viewed in a plan view;
A second transmitter for transmitting a sound signal based on the second signal, wherein the transmission direction is inclined at a predetermined angle to the opposite side of the first transmitter with respect to the axis, and a transmission direction of the sound signal; A receiver for receiving a reverberation signal from a target, a first correlation processor for performing a correlation process on the reverberation signal from the receiver using the first signal as a replica to obtain a correlation output, A second correlation processor that performs correlation processing using the second signal as a replica with respect to the echo signal from the receiver to obtain a correlation output, and a correlation output obtained by the first correlation processor, Second
A sonar target identification device comprising: a real / imaginary target discriminator for comparing correlation outputs obtained by a correlation processor with each other and discriminating a real target and an imaginary target from the result. . 3. A signal generator, a transmitter for emitting a signal from the signal generator in at least two directions, a receiver for receiving a reflected signal of a radiation signal from a target, and the receiver Phasing unit for generating a phasing beam in the direction of the signal received by the above, an energy detecting unit for detecting energy in each phasing beam, and comparing the respective energies detected by the energy detecting unit with each other. And a real / imaginary target identification unit for identifying a real target and an imaginary target from the result. 4. A first signal generator for generating a predetermined first signal, a second signal generator for generating the same signal as a second signal after a predetermined time, a transmission direction as viewed in plan Is tilted at a predetermined angle with respect to the axis of the ship, and emits an acoustic signal based on the first signal.
A second transmitter for transmitting a sound signal based on the second signal, wherein the transmission direction is inclined at a predetermined angle to the opposite side of the first transmitter with respect to the axis, and a transmission direction of the sound signal; A receiver for receiving a reverberation signal from a target, a signal receiving the signal from the receiver, and a phasing device for generating a phasing beam in a direction of a reflection angle of the signal from the target; A first energy detector for detecting energy in the phasing beam corresponding to the signal; a second energy detector for detecting energy in the phasing beam corresponding to the second signal; and the first and second energies. A sonar target identification device, comprising: a real / imaginary target identification unit for comparing the respective energies detected by the detector with each other and discriminating a real target and an imaginary target from the results. .