JPS6360867B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a homing device, and particularly to a homing device using an active sonar that travels underwater to track a target.

Conventionally, active sonar equipment is equipped with a transmitter and receiver, or a transducer for both transmitting and receiving, on an underwater vehicle, and after transmitting pulse modulated waves from the transmitter, the waves are reflected from the target. The incoming echoes can be received by scanning the transmitted angle range with a receiver with narrow beam directionality, or by preparing a large number of receivers with narrow beam directionality in each direction in advance. Either the narrow-angle beam scanning method detects the direction of the target and determines the steering direction, or the narrow-angle beam scanning method uses two receivers spaced apart at a certain distance and compares the output waveforms of each receiver. The direction of the target was determined using the phase difference detection method, which determines the direction of steering by determining the phase difference.

Therefore, in the narrow-angle beam scanning method, in order to improve the accuracy of direction detection, it is necessary to make the beam sharper, and both the transducer and receiver must have a radiation surface that is sufficiently large relative to the wavelength.
In other words, a radiation surface with a large aperture ratio is required.

In addition, homing devices need to detect targets from as far away as possible, and for this purpose, the best way to do this is to use low frequencies with low propagation loss, but homing devices have particular limitations due to size. For example, at low frequencies with long wavelengths of several KHz or less, the beam has a wide angle and has the disadvantage that the direction detection accuracy is extremely reduced.

On the other hand, in the phase difference detection method, the distance between the two receivers needs to be large relative to the wavelength;
(λ is the wavelength of the transmitted signal)
A phenomenon occurs in which the phase is the same in two or more directions within a 180 degree range, making it difficult to determine the true direction.
When the spacing is narrower than λ/2 due to limitations in the shape or size of the device, there is a drawback that the accuracy naturally decreases.

Furthermore, since the direction of the target is of course completely unknown when tracking the target begins, a transmitter with wide-angle transmission directionality is driven with high power to output a transmission signal, and this transmission signal Even after it begins to receive echoes from the target, it continues tracking with this high-power transmission. As mentioned above, it is necessary for homing devices to detect from as far away as possible, which inevitably requires long-term homing, which increases power consumption. There is a limit to the capacity of the typically battery-based transmitter on-board power supply that can be accommodated in the transmitter, and this has the drawback of subjecting the tracking time to a large degree of control.

The object of the present invention is to eliminate the above-mentioned drawbacks and to provide at least two receivers for each set of rudders of an underwater vehicle in a plane perpendicular to the rudder and parallel to the axis, and with a component perpendicular to the axis. The target is tracked by placing it at a position where the receiver has a target and receiving echoes of the target using the first transmission signal, which is initially low frequency and non-directional, and then tracking the target by comparing the wave number difference of the sound waves received by these receivers. let them do it;
When an underwater vehicle crosses the direction of the target and steers in the opposite direction, it is detected and tracked by switching the transmission signal to a second transmission signal that is a pulse modulated wave with narrow directionality and a higher frequency. This simple step of continuing the process can significantly reduce the consumption of transmitting power, greatly improve tracking time or detection distance, and is much faster than traditional target tracking methods using pulse modulated waves. An object of the present invention is to provide a homing device that can improve detection rate and accuracy.

In the device of the present invention, a transmitter is arranged at the head of the underwater vehicle on the axis of the underwater vehicle or around the axis, and at least two transmitters are arranged for each set of rudders of the underwater vehicle. Omnidirectional first transmission transmitted from the transmitter by arranging a receiver in a plane perpendicular to the rudder and parallel to the axis and having a component perpendicular to the axis; a wave number measuring means for measuring the wave number of each output signal of the at least two receivers that have received a target echo from the signal; a comparing means for comparing the wave numbers obtained by the wave number measuring means; and a comparing means for comparing the wave numbers obtained by the wave number measuring means. Steering means for operating the rudder of the underwater vehicle by the output of the means, and when the direction of the underwater vehicle steered by the output of the steering means exceeds the direction of the target and the rudder is steered in the opposite direction. Reverse rudder signal detection means detects this and outputs the transmitted signal by switching it to a second transmitted signal having a higher frequency and sharper directivity than the first transmitted signal, and causes the rudder to be operated in a direction directly facing the target. It is composed of:

Next, the present invention will be explained in detail with reference to the drawings.
FIG. 1 is a block diagram showing one embodiment of the present invention. The transmitter 1 receives a first pulse modulated wave signal 401 of a low frequency from the transmitter circuit 4, and the transmitter 2 receives a second pulse modulated wave signal of a sufficiently higher frequency than the pulse modulated wave 401 from the transmitter circuit 4. Receiving the wave signal 402, both radiate into the water as a transmitted sound wave, the echoes reflected from the target are received by receivers 3A and 3B and 3C and 3D having the same characteristics. In this embodiment, the receivers 3A and 3B are used to obtain azimuth information of the target, and the receivers 3C and 3D are used to obtain vertical (up and down) position information of the target.

The transmitter 1 has omnidirectional wave directivity, and the transmitter 2 is a transmitter with a narrow beam directivity as described later, and always emits a transmitted signal from one of the transmitters. do. Transmitters 1 and 2 can also be used by switching between two frequencies using one transmitter by utilizing the higher-order mode of the vibrator that constitutes the transmitters.
In this embodiment, two are used in consideration of simplifying the impedance matching circuit, frequency switching circuit, and high efficiency electro-acoustic conversion.

FIG. 2 is a transducer equipment diagram showing the arrangement of the transducer. As shown in the figure, the transmitters 1 and 2 are installed symmetrically around the axis X'-X'' inside the head 44 of the underwater vehicle 11, and the receivers 3A and 3B
is a set of rudders, namely submersible rudders 22A and 22B.
and parallel to the axis X′-X″.The Y′-Y″ axis indicates the direction perpendicular to the axis X′-X″, and the The receivers 3A and 3B are arranged symmetrically on the underwater vehicle 11, and the receivers 3C and 3D (not shown) are arranged vertically symmetrically as shown. Further, the rudders 33A and 33B (not shown) are arranged above and below the underwater vehicle 11 as shown in the figure.

In FIG. 1, at the start of target tracking, the underwater vehicle 11 first sends out a first pulse modulated wave signal 401 for wave transmission from the transmitting circuit 4, and the transmitter 1 that receives this transmits it as an electrical signal. It radiates into the water as a transmitted sound wave through acoustic conversion.

The first pulse modulated wave signal 401 uses a low frequency pulse modulated wave of approximately 5 KHz, and the transmitter 1 that inputs this has an omnidirectional transmission directivity characteristic, so the incident sound wave is omnidirectional. When a target at a distance is sufficiently large compared to the wavelength, it hits the target as a spherical wave, and the reflected echo is easily transmitted to the receivers 3A and 3B and 3C and 3C because the transmitted sound wave is omnidirectional. Captured and received by 3D.

Receiver output signal 301 of receivers 3A and 3B
A and 301B are input amplifier circuits 5A and 301B, respectively.
and 5B to the required level, and then input to the wave number measurement circuits 6A and 6B as input amplification circuit output signals 501A and 501B, respectively, and the receiver output signals 30 of the receivers 3C and 3D.
1C and 301D are input amplifier circuits 5, respectively.
After being amplified to the required level by C and 5D, the input amplifier circuit output signals 601C and 601
D is input to wave number measurement circuits 6C and 6D, respectively.

The transmitting circuit 4 transmits the first pulse modulated wave signal 401 described above and the second pulse modulated wave signal 4 described later.
02, and a transmission frequency switching circuit that switches between the two frequencies. The transmitted sound waves output from the transmitter 1 by the wave signals are directly input to the receivers 3A and 3B, and 3C and 3D, which are input to the input amplifier circuits 5A, 5B,
In order to prevent malfunctions caused by input to 5C and 5D, etc., a period of time that can be specified arbitrarily depending on the purpose and is synchronized with the pulse modulated wave to be transmitted and is longer than several milliseconds to several tens of milliseconds corresponding to the normal pulse width. In order to turn off the operation of each of these input amplifier circuits, a blanking pulse generation circuit is provided which outputs a negative gate voltage, a so-called blanking pulse 403, to the input circuits of the input amplifier circuits 5A, 5B, 5C and 5C. Furthermore, the second pulse modulated wave output circuit is equipped with an output level adjustment circuit to adjust the output of the second pulse modulated wave to the underwater vehicle 11.
It can be set in advance before cruising. The switching between the first and second pulse modulated waves is performed by the transmission frequency switching circuit described above, which inputs a reverse rudder signal 1001 output from a reverse rudder signal detection circuit 10, which will be described later.

Next, the principle of a method for steering the vehicle 11 using the outputs of these receiver groups will be explained.

FIG. 3 is an operational principle diagram showing the operation of this embodiment. 0 in FIG. 3 indicates the target and is assumed to be at the origin of the X and Y axes. P〓 indicates the sound pressure of the echo reflected from the target, and since it is located sufficiently far from the underwater vehicle 11 compared to the wavelength, P〓 can be regarded as a spherical wave.

The solid circular arc lines, ,... indicate the distribution of the maximum value of the sound pressure P〓 at a certain time t ₁ , and the dotted lines ′,
′, ′…′ indicate the distribution of the minimum value. Therefore, the difference between the solid line and the dotted line is λ/2.

Now, the position of the vehicle 11 at time t ₁ is P ₁
(t ₁ ) and the case where the vehicle moves in the direction of arrow 111 will be considered. It is assumed that the underwater vehicle reaches P ₂ (t ₂ ) at time t ₁ . Since the sound wave propagates a certain distance in the time t ₂ - t ₁ , the distribution of P〓 also changes, but to simplify the explanation of the principle, if we fix the distribution at t ₁ , the received During this time, wave device 3A',
, ′, , ′, can be seen.
On the other hand, during this time, the receiver 3B
You can see that it has crossed. Therefore, when the received wave outputs for the maximum and minimum sound pressure values are read by the wave number measurement and comparison means, it is possible to detect that one wave speed difference has occurred, and send a steering signal to the rudders 33A and 33B. The vehicle 11 is rotated to the right (direction of 0).

Next, assuming that it is at the position P ₃ (t ₃ ) at time t ₃ ,
If this continues as it is to the position of P ₄ (t ₄ ) at time t ₄ , the wave numbers obtained from the receivers 3A and 3B are 6 and 5, respectively, resulting in a difference of 1, and P ₄ ( At t ₄ ), the vehicle 11 is turned to the right.
In this way, in this case, the vehicle approaches target 0 while turning clockwise, and continues tracking until it directly faces target 0. Tracking continues until the target 0 and the underwater vehicle 11 face each other directly, but the movement of the vehicle 11 necessarily has inertia, and the output characteristics of the receivers 3A and 3B may change if the vehicle 11 moves too far from the directly facing direction. would reverse the situation described above. Furthermore, the purpose of the underwater vehicle 11 is ultimately to face the target 0 and track it, but when it faces the target 0 directly, the rate at which echoes from the target 0 are input, that is, the echo capture rate, significantly decreases. Therefore, in many cases, it is not necessary to maintain the transmission power of the first pulse modulated wave signal 401 that has been transmitted so far in the subsequent head-to-head tracking. Therefore, the vehicle 11 crosses the direction of the target 0 and reaches the receiver 3.
When the output characteristics of A and 3B are reversed and the navigation object 11 is about to face the target 0, a reverse rudder detection means is provided to detect this output and reverse rudder. The wave number of the echo is increased by switching to a pulse modulated wave signal 402, that is, a pulse modulated wave signal with a frequency several times higher than that of the first pulse modulated wave signal 401, and this is further transmitted to a pulse modulated wave signal having a narrow-angle transmission directivity. The device 2 outputs a narrow beam of transmitted sound waves to continue tracking. In this case, the narrow angle transmission directivity that the transmitter 2 should have is the distance between the vehicle 11 and the target 0, the dimensions of the acoustic radiation surface of the transmitter 2,
The directivity angle is determined depending on the frequency etc. of the second pulse modulated wave, but this transmitting directivity is also
It also brings about a directional gain corresponding to the directional width, that is, the sharpness of the directional angle, for omnidirectional transmitted sound waves, and it can be detected by decreasing the transmitting power by this amount and increasing the tracking time, or by leaving the transmitting power as it is. The distance can be increased and either can be arbitrarily selected as desired. In this state, the underwater vehicle 11 faces the target 0 almost directly, and is constantly steered in a direction in which the wave number difference between the output signals of the receivers 3A and 3B becomes zero, and continues to track the target 0 directly.

In the case of this embodiment, as described above, an output level adjustment circuit is provided in the output circuit of the second pulse modulated wave signal 402 of the transmitting circuit 4, so that the output level can be adjusted and set in advance in a few steps. The aim is to extend the tracking time or increase the detection distance depending on the purpose of use of the homing device.

In addition, the wave transmitting directivity that the transmitter 2 should have is such that the vehicle 11 faces the target almost directly, moves to tracking, maintains the facing direction, and maintains the required echo capture rate. It is preferable that the width be as narrow as possible in order to increase the directivity gain. Practically speaking, if the operating conditions of the homing device are taken into account, the temperature is 20 degrees or more.
If there is a directivity width of about 30 degrees, there is no risk of reducing the echo capture rate in the facing direction, and in this embodiment, this is set to approximately 25 degrees, and this is set from the transmitter 2 and the first pulse modulated wave 401. is also obtained by combining with the second pulse modulated wave 402 having a sufficiently high frequency.

In this way, the vehicle 11 tracks and pursues the target 0, but during this time, the echo reception pause time due to the blanking pulse when transmitting the transmission signal is off for a few ms to several tens of ms of the transmission pulse width. , so it is very short, and during this time underwater vehicle 1
1 continues cruising while maintaining the steering state immediately before transmission, and between the pulses of the pulse modulated wave to be transmitted, information is obtained from the input echo and steers accordingly, except when receiving an echo. It continues tracking while maintaining the steered cruising state based on the information obtained from the previous echo.

As described above, the underwater vehicle 11 initially starts tracking with an improved initial detection rate by transmitting omnidirectional sound waves, enters the tracking state by inputting echoes from the target, and then continues underwater navigation. When the body 11 exceeds the target direction and receives a reverse rudder signal, this is detected, and the transmitted sound wave is switched to a narrow beam directional sound wave with a higher frequency, reducing power consumption in accordance with the directional gain. Based on the high echo capture rate and increased wave number information obtained from the target in the opposite direction, it is possible to continue extremely stable and highly accurate tracking while increasing either the tracking time or tracking distance depending on the purpose. .

In addition, Fig. 3 shows a receiver 3A that inputs azimuth information.
and 3B, vertical (up and down) direction tracking performed by the receivers 3C and 3D can be performed using exactly the same principle.

The explanation will be given by returning to FIG. 1 again.

The echoes input to the wave receivers 3A and 3B are amplified by input amplifier circuits 5A and 5B, and input to wave number measurement circuits 6A and 6B.

The wave number measurement circuits 6A and 6B have a frequency counter circuit and an output amplification circuit, and count the wave number of the next input signal by the frequency counter circuit, amplify it to a required level, and then convert it into a digital wave number information signal. It is sent to the wave number difference comparison circuit 7 as 601A and 601B.

The wave number difference comparison circuit 7 receives the input wave number information signal 60.
It has a two-channel processing circuit for 1A and 601B, and each channel is used to control a built-in program that is temporarily stored in an input register and set based on previously known information such as the navigation conditions of the vehicle 11. After reading out the stored contents one after another and converting them into analog signals with a level corresponding to the wave number using a D-A converter, the processed outputs of these two channels are input to a differential amplifier circuit for input. An output voltage corresponding to the level difference is obtained, and this is converted to DC through a rectifier circuit in accordance with the wave number.
Output as voltage. Therefore, the polarity of the DC voltage output from the differential amplifier circuit changes depending on the magnitude of the input level corresponding to the input to the two-channel processing circuit, that is, the wave number information signals 601A and 601B.

In this embodiment, a method is used in which the wave number information signal 601A is used as a reference and the wave number information signal 601B is differentially amplified.
If the number of waves included in 1A is greater than the number of waves included in waveform information signal 601B, the differential amplifier circuit
The polarity of the DC output voltage is positive, and in the opposite case it is negative, and when the wave number differences are equal, no output is produced.

The echoes received by the wave receivers 3C and 3D are also output as wave number information signals 601C and 601D from the same wave number measuring circuits 6C and 6D to the wave number measuring circuits 6A and 6B, respectively, in exactly the same manner as described above. These are input to the wave number difference comparison circuit 7B, which is the same as the wave number difference comparison circuit 7A, and are output as the wave number difference information signal 701B to the steering signal generation circuit 8.
sent to.

The steering signal generation circuit 8 includes receivers 3A and 3B.
a rudder signal generation circuit that generates a steering signal corresponding to the output of the receivers 3C and 3D; It has two selective amplification circuits corresponding to the polarities of the input wave number difference information signals 701A and 701B, amplifies the input signals to the required level, and sends this output steering signal 801 to the steering circuit 9 and reverse steering signal detection. circuit 10
Send to.

Even if the reverse steering signal detection circuit 10 receives this steering signal 801 as described later, it does not operate until the underwater vehicle 11 exceeds the target direction and the polarity of this signal becomes negative. When the vehicle is in the pre-rudder state, the steering signal 801 operates only the steering circuit 9.

The steering circuit 9 includes a rudder drive circuit that drives the rudders 33A and 33B, and a rudder drive circuit that drives the submersible rudders 22A and 22.
A steering signal 801 output from the steering signal generation circuit operates the drive actuator of each drive circuit to perform steering.

Steering signal 801 output from the steering signal generation circuit 8
is also sent to the reverse rudder signal detection circuit 10. As already mentioned with reference to the operating principle diagram in FIG.
If the direction of 1 exceeds the target direction, the wave number difference comparison circuit 7
When the polarity of the wave number difference information signal 701A output by A changes, the steering signal generation circuit 8 that receives this signal with changed polarity amplifies it with a negative selection receiving circuit that selectively receives only negative signals. has a polarity of
Selectively receives only 701A output as a DC voltage, converts the polarity of this using an operational amplifier circuit, and then outputs it as a pulse from a Schmitt trigger circuit that triggers when the level exceeds a preset operating threshold. Then, a reverse rudder signal 1001 is obtained which is pulse-amplified to a predetermined level and output, and sent to the transmission circuit 4, and the transmission frequency switching circuit converts the transmission signal from the first pulse modulated wave to the second pulse modulated wave. Then, the underwater vehicle 11 receives the second pulse modulation wave, which has a high echo capture rate from a direction almost directly facing the target, has a sufficiently higher frequency than the first pulse modulation wave, and therefore has more wave number information. Highly accurate tracking is achieved by transmitting a narrow beam signal using waves. When receiving echoes almost directly facing the target in this way, it is difficult for the wave number difference between the echo inputs received by the receivers 3A and 3B to occur, and when the wave number difference is zero, no steering is performed, and the previous steering Maintaining this position, it continues to sail straight ahead, repeating such maneuvers until it approaches the target from almost directly opposite direction.

The above operations are performed in exactly the same manner for vertical (up and down) direction steering by the receivers 3C and 3D.

It is clear that this tracking method performed by detecting a reverse rudder signal can be carried out in exactly the same way whether the target is viewed to the right of the underwater vehicle 11 or to the left. Furthermore, if the underwater vehicle 11 were to start traveling in the completely opposite direction to the target, it would move away from the target without changing direction, but such an opportunity is extremely rare, and there are almost no practical problems. Although it is difficult, in order to obtain the steering signal as quickly as possible, this extremely rare problem can be avoided by setting the so-called counter rudder in advance so that the initial motion of the underwater vehicle 11 is slightly rotated. I can do it.

The present invention provides at least two wave receivers for each set of rudders of an underwater vehicle to generate a wave number difference of an output signal that is within a plane perpendicular to the rudder, parallel to the axis, and has a component perpendicular to the axis. After detecting a reverse rudder signal, the transmitter switches the transmitter signal to a pulse modulated wave with higher frequency and narrow beam directionality to obtain directivity gain and reduce the transmitter power consumed. There are basic characteristics in this embodiment, and various modifications of this embodiment are conceivable.

For example, in this embodiment, as shown in FIG. 3, the wave number is read every λ/2, but this may also be done every 1 λ, and it is expected that it will take a long time to produce a wave number difference. If
Using multiple wave number measurement circuits, wave number comparison difference circuits, etc.
Smooth continuous tracking operation can be achieved by delaying the start point of wave number measurement little by little and operating them in parallel, and switching and connecting the steering signal generation circuit and the steering circuit in synchronization with their respective outputs.

Furthermore, if desired, it is possible to easily set the omnidirectional first transmission signal used at the beginning of the tracking operation to CW, taking into account the tracking conditions of the underwater vehicle 11, etc. In this case, CW is used. In order to prevent the transmitted waves from directly inputting to the receivers 3A, 3B, 3C, and 3D and causing malfunctions, all of these receivers are set at λ/2 (λ is the wavelength of the transmitted signal) or β. The outputs of each of these receiver groups are sum-connected before the reverse rudder, which is in the CW transmission state, and difference-connected after the reverse rudder, which is in the pulse-modulated wave transmitting state. By doing so, the receiving directivity is directed in a direction perpendicular to the axis of the underwater vehicle 11 before reverse rudder, and after reverse rudder, the reverse rudder detection signal is parallel to the axis, that is, in the traveling direction of the underwater vehicle 11. This can be easily implemented by a method such as switching in response to the occurrence of 1001.

Further, it is also possible to easily implement the contents of this embodiment in combination with a conventional homing device that uses reflected echoes by a single pulse modulated wave. For example, before reverse steering, wide-area tracking is performed using the low-frequency omnidirectional transmitted sound waves according to this embodiment to improve the initial detection rate, and after reverse steering, the state is such that the input echo capture rate is high while facing the target almost directly. It is clear that it is also possible to continue tracking by switching to pulse transmission and reception using a conventional homing device, if desired.

Note that although two transmitters are used in this embodiment, it is also possible to replace them with one transmitter that utilizes the higher-order vibration mode of the transmitter.
An arbitrary number of receivers can be installed for one set of rudders, and the outputs of these receivers can be inputted two at a time as in this embodiment, and processed by switching one after another at a specified time difference. It is also clear that it can be easily implemented.

All of the above can be easily implemented without detracting from the gist of the present invention.

As explained above, according to the present invention, at least two wave receivers are provided for each set of rudders of an underwater vehicle in a plane perpendicular to the rudder and parallel to the axis, and having a component perpendicular to the axis. The receiver is placed at a position such as this, receives the echo of the target by the first transmission signal that is initially low frequency and omnidirectional, and tracks over a wide area by comparing the wave number difference of the sound waves received by these receivers. When the underwater vehicle crosses the direction of the target and reverses direction, the system detects this and switches the transmission signal to a second transmission signal that is a pulse modulated wave with narrow directionality and a higher frequency. This simple method of continuing tracking can significantly reduce transmission power consumption, significantly improve tracking time or detection distance, and is superior to conventional target tracking methods using single pulse modulated waves. This has the effect of realizing a homing device that can significantly improve initial detection rate and accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a transducer layout diagram showing the arrangement of the transmitter and receiver, and FIG. 3 is an operating principle diagram showing the principle of operation of the present invention. 1... Transmitter, 3A, 3B, 3C, 3D... Receiver, 4... Transmission circuit, 5A, 5B, 5C5D... Input amplifier circuit, 6A, 6B, 6C, 6D... Wave number measurement circuit, 7A, 7B... Wave number Difference comparison circuit, 8...Reverse rudder signal generation circuit, 9... Steering circuit, 10... Reverse rudder signal detection circuit, 11... Underwater vehicle.

Claims (1)

[Claims] 1 At the head of the underwater vehicle, on the axis of the underwater vehicle,
or a transmitter is arranged around the axis, and at least two receivers are arranged for each set of rudders of the underwater vehicle in a plane perpendicular to the rudder, parallel to the axis, and relative to the axis. The wave number of each output signal of the at least two receivers is arranged at a position having a vertical component and receives a target echo caused by the omnidirectional first transmission signal transmitted from the transmitter. A wave number measuring means for measuring, a comparing means for comparing the wave numbers obtained by the wave number measuring means, a steering means for operating the rudder of the underwater vehicle based on the output of the comparing means, and an output of the steering means. When the direction of the underwater vehicle being steered exceeds the direction of the target and the rudder is steered in the opposite direction, this is detected and the transmitting signal is transmitted with a higher frequency and sharper directivity than the first transmitting signal. 1. A homing device comprising reverse rudder signal detection means for switching to and outputting a second transmission signal and operating a rudder in a direction directly facing a target.