JPH07294618A - Method for measuring direction of signal - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy of direction of a target signal. CONSTITUTION:A signal spread in an acoustic medium is received by wave detectors 1-i (i=1 to N) and converted into an electric signal. A wave-receiving surface from a target of the wave detector located at the center of the wave detectors 1-i is taken as a phased surface by a phasing device 12. A sum (tauik+DELTAtauik) of a propagation time tauik between each wave detector 1-i and the phased surface to each of a plurality of estimated directions tauk (k=1-m) and a correction value DELTAtik of the propagation time stored in a propagation correction value table 11 is obtained on an assumption that the target is propagated at the same speed inside and outside an acoustic dome. The electric signal output from each wave detector 1-i is corrected by the sum (tauik+DELTAtik). A sum of the corrected electric signals is output to a direction-measuring device 3 as a beam of the direction thetak. The direction-measuring device 3 obtains direction of the maximum power among the receiving beams for every direction, and outputs the direction as a direction of the target.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal azimuth measuring method for measuring a target signal azimuth in a sonar system or the like using a receiver array housed in a dome such as an acoustic dome.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field,
For example, some documents were described in the following documents. Literature; Robert J. Uric
k) "Principles of Underwater Sound" (198
0), McGraw-Hill Book Company (McGraw-Hil
Book Company) (US) FIG. 2 is a functional block diagram of a signal bearing measuring device for carrying out the signal bearing measuring method. This conventional signal azimuth measuring device has a receiver array 1 including a plurality of receivers 1-i (i = 1 to N) for receiving signals from a target housed in an acoustic dome. There is. On the output side of each wave receiver 1-i, a plurality of target azimuths θ _k (k = 1 to 1) to be predicted are provided.
m), a phase shifter 2 for obtaining a propagation time for a signal from the target to propagate between the phase matching surface corresponding to m) and the receiver 1-i, and forming a beam for each azimuth θ _k based on the propagation time. Are connected. An azimuth measuring device 3 is connected to the output side of the phase adjuster 2 for calculating the azimuth θ of the beam having the maximum output intensity among the beams of the azimuth θ _k . The target signal bearing θ is output from the bearing measuring device 3.

FIG. 3 is a diagram for explaining the principle of measuring the conventional signal direction described in the above document. In FIG. 3, the wave-receiving surface of the signal received from the target received at the point O located at the center of the points X ₁ and X ₂ is the phase-matching surface 9, and the space between the phase-matching surface 9 and the point X ₁ is the target. The propagation time τ ₁ of the signal of is propagated by the following equation (1), and the propagation time τ ₂ of the signal of the target traveling between the phase matching surface 9 and the point X ₂ is represented by the following equation (2). be able to. τ ₁ = d ₁ · cos θ / c (1) τ ₂ = d ₂ · cos θ / c (2) where d ₁ is the distance between the point O and the point X _1, and d ₂ Is point O
Is the distance between the point and the point X ₂ , θ is the target azimuth,
c is the speed of sound. Point X for the propagation time of τ ₁ or τ _2
When the signal S ₁ or S ₂ received at ₁ or X ₂ is corrected, the phase of this corrected signal and the signal received at point O are aligned, and the sum of the signal received at point O and the corrected signal (hereinafter , Which is called a beam with an azimuth θ). Therefore, a beam having a plurality of predicted signal azimuths θ _k is created in advance, and the azimuth of the beam with the maximum output of these beams is measured as the target azimuth.

Next, a signal bearing measuring method will be described with reference to FIG. The signal propagating through the acoustic medium from the target is received by each receiver 1-i (i = 1 to N), and each receiver 1-i is received.
It is converted into an electric signal by i and output to the phase adjuster 2. In the phase phasing device 2, a plurality of predicted azimuths θ _k (k = 1 to m) are set with the wave receiving surface from the target received by the wave receiving device located in the center among the wave receiving devices 1-i as a phase phasing surface. corrects the electric signal output by the receiving transducer 1-i between the receivers and the phasing surface previously obtained by the propagation time for a signal from the target is propagated relative, orientation theta _k Beam is generated and output to the azimuth measuring device 3. In the azimuth measuring device 3, these azimuths θ _k
The beam with the maximum output is obtained and the azimuth θ of the beam is output as the signal azimuth.

[0005]

However, the conventional signal azimuth measuring method has the following problems. In the sonar system in which the receiver array is housed in the dome, if the acoustic medium is different between the outside and inside of the dome and the sound velocity is different, the direction measurement is performed for the following reasons (a) and (b). There was a problem that an error occurred. (A) The signal entering the dome is refracted at the boundary surface of the dome. (B) Since the propagation time of the signal arriving at each receiver is different between the case where there is no dome and the case where there is a dome, the propagation time calculated by the phase shifter 2 includes an error. FIG. 4 is a diagram for explaining a problem of the conventional signal azimuth measuring method using the receiver array housed in the acoustic dome. As shown in FIG. 4, the wave receivers are arranged at points X ₁ , X ₂ , O on a straight line in the circular acoustic dome 10. Here, the point O is the center of the acoustic dome 10 and the points X ₁ , X ₂ , O. When phasing in the direction θ with the point O as the center of phasing, the signals S ₁ and S ₂ reaching the points X ₁ and X ₂ are obtained.
Then, in the portions indicated by the distances l ₁ and l ₂ within the acoustic dome 10 until the signal from the target reaches the points X ₁ and X ₂ , the speed of sound is different from that outside the acoustic dome 10, so the distance l ₁ , L ₂ is different from the case where the acoustic dome 10 does not exist.

That is, the time t ₁ during which the signal S ₁ passes the distance l ₁ without the acoustic dome 10 is t ₁ = l ₁ / c (3), and when the acoustic dome 10 is present, Signal S ₁ is distance l
_The time t ₁ ′ for passing ₁ is t ₁ ′ = l ₁ / c ′ (4). Where c is the speed of sound of the medium outside the dome, and c
′ Is the speed of sound of the medium in the dome. For this purpose, the signal S
_{In the case of 1} , a difference of Δt ₁ = t ₁ ′ −t ₁ (5) occurs in the propagation time of the portion at the distance l ₁ . Similarly, in the signal S ₂ , there is a difference of Δt ₂ = t ₂ ′ −t ₂ (6) in the propagation time of the portion at the distance l ₂ . Therefore, with the point O as the center of phasing, the azimuth θ
In the case of phasing to the signals S ₁ and S arriving at the points X ₁ and X ₂ ,
_{For 2} , the propagation time must be corrected to τ ₁ + Δt ₁ and τ ₂ + Δt ₂ . However, in the conventional signal azimuth measuring method, since the correction of Δt ₁ or Δt ₂ is not performed, an error occurs in the azimuth measurement result θ.

[0007]

To solve the above problems, a first aspect of the present invention is a signal azimuth measuring method, wherein a receiver array having a plurality of receivers housed in a dome is provided from a target. A signal is received, and the signal from the target propagates between the phase matching surface corresponding to the azimuth of the target and the receiver based on the difference in the propagation speed of the signal from the target outside and inside the dome. Then, a beam corresponding to the target azimuth is created based on the propagation time and the received signal received by the receiver, and the target azimuth is measured based on the output of the beam. ing. A second invention is a signal azimuth measuring method, wherein a signal from a target is received by a receiver array having a plurality of receivers housed in a dome,
Assuming that the propagation speed of the signal from the target is equal on the outside and inside of the dome, the propagation time of the signal from the target propagating between the phase matching surface corresponding to the azimuth of the target and the receiver. A beam corresponding to the target azimuth based on the propagation time and the received signal received by the receiver, and the azimuth of the target before correction is measured based on the output of the beam. However, the azimuth of the target before correction is corrected to be the target azimuth based on the difference in the propagation velocity of the signal from the target between the outside and the inside of the dome.

[0008]

According to the first aspect of the present invention, the signal azimuth measuring method is configured as described above, so that the receiver array having a plurality of receivers housed in the dome receives the signal from the target. Since the propagation velocity of the signal from the target is different between the outside and the inside of the dome, for each of the multiple azimuths predicted by the signal from the target, the phasing surface corresponding to each azimuth and the wave receiver are The propagation time for propagation is determined, the output of the receiver array is corrected based on the propagation time, and a beam corresponding to the predicted azimuth is created. The beam having the maximum output among the outputs of the plurality of beams is set as the azimuth from the target. According to the second aspect of the invention, it is assumed that the propagation speed of the signal from the target is the same on the outer side and the inner side of the dome, and propagates between the phase matching surface and the wave receiver corresponding to a plurality of predicted azimuths. The propagation time is obtained, the output of the receiver array is corrected based on the propagation time, and the beam corresponding to the predicted azimuth is created. Then, the beam with the maximum output among the outputs of the plurality of beams is set as the azimuth before correction from the target. Since the propagation speed of the signal from the target is different between the outside and the inside of the dome, the azimuth before correction includes an error. Therefore, the azimuth of the target before correction is corrected based on the difference in the propagation speed of the signal from the target between the outside and the inside of the dome. Therefore, the above problem can be solved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a functional block diagram of a signal bearing measuring apparatus for carrying out the signal bearing measuring method of the first embodiment of the present invention, showing a conventional signal bearing measuring apparatus. Elements common to those in FIG. 2 are designated by common reference numerals. In this signal azimuth measuring device, the signal azimuth θ _k (k = 1 to m) predicted based on the difference in sound velocity inside and outside the acoustic dome, and each wave receiver 1 are used.
A propagation time correction value table 11 for storing the propagation time correction value Δt _ik obtained in the same manner as the expression (5) or the expression (6) is provided for each −i (i = 1 to N), and the phase adjuster 12 Propagation time correction value Δt _ik stored in the propagation time correction value table 11
Based on the above, the propagation time obtained by assuming that the sound velocities inside and outside the acoustic dome are equal is corrected, and the beam of each azimuth θ _k is created based on the corrected propagation time. As shown in FIG. 1, this signal azimuth measuring device has a plurality of wave receivers 1-i (i = 1 to N) arranged in an acoustic dome (not shown) and receiving signals from a target. There is. A propagation time correction value table 11 is provided. A phaser 12 is connected to each of the wave receivers 1-i and the output side of the propagation time correction value table 11. An azimuth measuring device 3 for measuring a signal azimuth is connected to the output side of the phase adjuster 12. From the azimuth measuring device 3, the signal azimuth (θ + Δθ) in which the propagation time is corrected due to the difference in sound velocity inside and outside the acoustic dome
Is output.

The signal direction measuring method will be described below with reference to FIG. The signal propagating through the acoustic medium is received by each of the wave receivers 1-i (i = 1 to N). Each wave receiver 1-i
Then, the received signal is converted into an electric signal and output to the phase adjuster 12. In the phase phasing device 12, a plurality of predicted azimuths θ _k (k = 1 to m) are predicted with the wave receiving surface from the target received by the wave receiving device located at the center among the wave receiving devices 1-i as the phasing surface. Against
When the propagation velocities of the target inside and outside the acoustic dome are equal, the propagation time τ _ik of the signal from the target between each receiver 1-i and the phasing plane for the direction θ _k and the propagation time correction value table 1
The sum of the propagation time correction value Δt _ik stored in 1 (τ _ik + Δ
t _ik ), and each wave receiver 1− for a time (τ _ik + Δt _ik ).
The electric signal output by i is corrected. Then, in the phase adjuster 12, the N sums of the corrected electric signals are taken,
This is output to the azimuth measuring device 3 as a beam of azimuth θ _k . The azimuth measuring device 3 obtains the azimuth having the maximum power among the outputs of the reception beams of the azimuth θ _k , and outputs this azimuth as the target azimuth. As described above, in the first embodiment, the propagation time propagating between the phase matching surface and each of the wave receivers 1-i is propagated as the propagation time correction value based on the target propagation velocity inside and outside the acoustic dome. Stored in the time correction value table 11,
The phase adjuster 12 corrects the propagation time based on the propagation time correction value to create a beam of each azimuth θ _k , and the azimuth measuring device 3 measures the target azimuth. Therefore, the accurate target azimuth is measured. There is an advantage that can be done.

Second Embodiment FIG. 5 is a functional block diagram of a signal bearing measuring apparatus for carrying out the signal bearing measuring method of the second embodiment of the present invention, showing a conventional signal bearing measuring apparatus. Elements common to the elements in 2 are assigned common reference numerals. In this signal bearing measuring device, the bearing measuring device 3 is added to the conventional signal bearing measuring device.
An azimuth measurement error correction value table 21 that stores a correction value Δθ _k for each of a plurality of azimuths θ _k (k = 1 to m) predicted for correcting the error Δθ with respect to the azimuth θ calculated by
And the adder 22 is provided. This signal bearing measuring device includes a plurality of wave receivers 1-i (i = 1 to N) for receiving signals from a target housed in an acoustic dome (not shown).
1 has a receiver array 1. Each wave receiver 1-i
On the output side of, the velocity at which the signal from the target propagates between the phase matching surface corresponding to the plurality of predicted target azimuths θ _k and the receiver 1-i is equal inside and outside the acoustic dome, A phase adjuster 2 is connected to obtain a propagation time of a signal from a target and create a beam corresponding to the azimuth based on the propagation time and the received signal received by the receiver 1-i. An azimuth measuring device 3 is connected to the output side of the phase adjuster 2 for calculating the azimuth θ of the beam that maximizes the output intensity of the beam for each azimuth. The azimuth measurement error correction value table 21 that stores the correction value of the signal azimuth calculated in advance based on the difference in the propagation velocity of the signal from the target inside and outside the acoustic dome is the azimuth corresponding to the azimuth θ. It is connected to the azimuth measuring device 3 in order to output the correction value Δθ. Azimuth measuring device 3 and azimuth measurement error correction value table 2
An adder 22 is connected to the output side of 1. The corrected target azimuth (θ + Δθ) is output from the adder 22.

The signal direction measuring method will be described below with reference to FIG. The signal propagating in the acoustic medium from the target is received by each wave receiver 1-i (i = 1 to N), converted into an electric signal by each wave receiver 1-i, and output to the phaser 2. To be done. In the phase adjuster 2, when the wave receiving surface from the target received by the wave receiver located in the center of the wave receivers 1-i is used as the phase adjusting surface, the propagation speeds of the target inside and outside the acoustic dome are equal. The propagation time τ _ik of the signal from the target between each of the receivers 1-i and the phasing plane for the direction θ _k is determined, and the propagation time τ _ik
Then, the electric signal output from each of the wave receivers 1-i is corrected to form a beam having an azimuth θ _k , and the beam is output to the azimuth measuring device 3. The azimuth measuring device 3 obtains the beam with the maximum output among the beams of these azimuths θ _k , outputs the signal azimuth θ of the beam to the adder 22, and corresponds to the signal azimuth θ from the azimuth measurement error correction value table 21. The correction value Δθ is searched for and the correction value Δθ is output to the adder 22. The adder 22 adds Δθ to the azimuth θ output from the azimuth measuring device 3 and outputs the added value (θ + Δθ) as the target signal azimuth. As described above, in the second embodiment, the azimuth θ output from the azimuth measuring device 3 is corrected by the correction value Δθ stored in the azimuth measurement error correction value table 21, so that an accurate target azimuth can be obtained. It has the advantage that it can be measured. The present invention is not limited to the above embodiment, and various modifications can be made. The following are examples of such modifications. In the azimuth measurement error correction value table 21,
The correction value may be obtained by actual measurement.

[0013]

As described in detail above, according to the first aspect of the invention, the receiver array having a plurality of receivers housed in the dome receives the signal from the target, and the outside of the dome is received. Based on the difference in the propagation velocity of the signal from the target between the inside and the inside,
A signal from a target determines a propagation time for propagating between a phase matching surface corresponding to the azimuth of the target and the receiver, and the propagation time,
Also, a beam corresponding to the target azimuth is created based on the received signal received by the wave receiver, and the target azimuth is measured based on the output of the beam, so that the accurate target azimuth can be measured. According to the second aspect of the invention, the azimuth of the target before the correction is corrected based on the difference in the propagation speed of the signal from the target between the outside and the inside of the dome, so that the accurate azimuth of the target can be measured. .

[Brief description of drawings]

FIG. 1 is a functional block diagram of a signal bearing measuring apparatus for carrying out a signal bearing measuring method according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram of a signal bearing measuring device for implementing a conventional signal bearing measuring method.

FIG. 3 is a principle diagram of a conventional signal azimuth measuring method.

FIG. 4 is a diagram for explaining a problem of a conventional signal azimuth measuring method.

FIG. 5 is a functional block diagram of a signal bearing measuring apparatus for carrying out the signal bearing measuring method according to the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Wave receiver array 1-1, 1-2, ..., 1-N Wave receiver 2,12 Phase adjuster 3 Azimuth angle measuring device 9 Phase adjusting surface 10 Acoustic dome 11 Propagation time correction value table 21 Direction measuring error correction Value table 22 Adder

Claims (2)

[Claims] 1. A receiver array having a plurality of receivers housed in a dome receives a signal from a target, and based on a difference in propagation velocity of the signal from the target outside and inside the dome. A signal from the target propagates between the phase matching surface corresponding to the target azimuth and the wave receiver, and calculates the propagation time based on the propagation time and the received signal received by the wave receiver. A signal azimuth measuring method comprising: forming a beam corresponding to a target azimuth and measuring the target azimuth based on an output of the beam. 2. A receiver array having a plurality of receivers housed in a dome receives a signal from a target, and it is assumed that the propagation speed of the signal from the target is equal to the outside and inside of the dome. Then, the propagation time that the signal from the target propagates between the phase matching surface corresponding to the target azimuth and the wave receiver is obtained, and based on the propagation time and the received signal received by the wave receiver. A beam corresponding to the direction of the target is created, the direction before correction of the target is measured based on the output of the beam, and based on the difference in the propagation velocity of the signal from the target inside and outside the dome, A signal azimuth measuring method, wherein the azimuth of the target before correction is corrected to be the target azimuth.