JPH04264282A - Azimuth detecting device - Google Patents

Abstract

PURPOSE:To facilitate execution of determination as to whether the incoming direction of an acoustic wave is in the direction of plus or in the direction of minus in respect to the direction of a normal line to the direction of arrangement of a receiver array. CONSTITUTION:Two delay circuits are set so that a phased plane is in the direction being inclined at + or -45 deg., for instance, to the direction of a normal line of a receiver array. When a spatial frequency is analyzed by an MEM method, for instance, outputs of two azimuth data forming elements are B+C (B'+C') in the range of 0 deg. to 45 deg. and A+D (A'+D') in the range of 45 deg. to 90 deg.. Herein no signal is generated in A and D', since they are located in the back area of the receiver array. Two azimuth selecting circuits take the data in the range of 45 deg. to 90 deg. (D, A') out of the outputs of the azimuth data forming elements. An azimuth synthesizing circuit sets the data in the range D, by conversion, in a range of -45 deg. to 0 and the data in the range A', likewise, in a range of 0 deg. to +45 deg., and forms and outputs one azimuth data.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azimuth detection device for detecting the azimuth of incoming sound waves underwater.

0002

[Prior Art] As a direction detection device that receives noise sound waves generated by underwater targets, echoes from active sonar devices, etc., and detects their direction of arrival, the one shown in FIG. 5 is conventionally known. .

[0003] In FIG. 5, N receivers 1 are a receiver array arranged in a straight line at intervals d equal to or less than 1/2 wavelength of the incoming sound waves, and receive the incoming sound waves and convert them electrically. . The output of each receiver is filtered by corresponding N bandpass filters 2 to remove unnecessary noise, and each data latch circuit 4
Enter.

Here, as shown in FIG. 6, when a sound wave is incident at an arrival direction at an angle θ from the normal direction to the arrangement direction of the N receivers 1, the output of the #Nth receiver 1 is SN
is defined as the following equation 1.

[0005]

[Math 1]

Output SM of the #M (M<N)th receiver 1
is as shown in Equation 2 below.

[0007]

[Math 2]

[0008] Then, the frequency of the arriving sound wave is f, and the wavelength is λ.
Then, ω=2πf, k=2π/λ, l=dsin
Since θ is substituted, the following equation 3 is obtained. Note that in Equation 3, (sin θ)/λ is called a spatial frequency (frequency of vibration per unit length), and is expressed as μ.

[0009]

[Math 3]

In other words, if the outputs of each receiver are sampled simultaneously at time t0, the output SM of the #Mth receiver 1 will be
is the following equation 4.

[0011]

[Math 4]

This indicates that the signal of spatial frequency μ is sampled at intervals d, as shown in the output example of FIG. Therefore, the condition d≦λ/2 is required. The data latch circuit 4 performs this simultaneous sampling.

The frequency analysis circuit 5 includes the data latch circuit 4
N sample signals are received, and frequency analysis is performed using the MEM method (maximum entropy method), FFT (fast Fourier transform) method, etc. to determine the spatial frequency μ.

[0014] The spatial frequency/azimuth conversion circuit 6 has μ=(s
From the relationship of in θ)/λ, the azimuth angle θ(θ=arcsin
(μ・λ)) and outputs the direction data. As described above, the data latch circuit 4, the frequency analysis circuit 5, and the spatial frequency/azimuth conversion circuit 6 collectively constitute the azimuth data forming section.

[0015]

[Problem to be Solved by the Invention] In the above-mentioned conventional direction detecting device, a method that does not determine the sign of the frequency for spatial frequency analysis (the MEM method is a typical example, but the FFT method may also not determine the sign) is used. If used, there is a problem in that it is not possible to correctly distinguish sound waves arriving from the negative direction.

For example, FIG. 7(a) shows various aspects of the sound wave arrival direction, and FIG. 7(b) shows the azimuth data output as a result of MEM processing. 0°, the left side of the arrangement direction is -90° azimuth,
If the azimuth angle is +90° to the right, the analysis result of the arriving wave ■ in the so-called first quadrant (positive azimuth) in the range of 0° to +90° will be within the range of 0° to +90°. ,0
Similarly, the analysis result of the arriving wave ■ in the so-called second quadrant (minus direction) in the range of -90° is 0° to +90°.
It ends up being within the range of .

An object of the present invention is to analyze spatial frequencies using a method that does not determine the sign of the frequency, so that the direction of arrival of a sound wave is in the so-called first quadrant (plus An object of the present invention is to provide an orientation detecting device that can determine whether the object is on the so-called second quadrant (negative direction) side or the so-called second quadrant (minus direction orientation) side.

[0018]

Means for Solving the Problems In order to achieve the above object, the orientation detecting device of the present invention has the following configuration. That is, the direction detection device of the present invention includes a receiver array in which N receivers for receiving incoming sound waves underwater are linearly arranged at equal intervals of 1/2 wavelength or less of the incoming sound waves; and N passband filters provided for each of the N passband filters; provided corresponding to each of the N passband filters, with a phasing surface extending from the normal direction to the arrangement direction of the receiver array to the so-called first
N first and second delay circuits that delay the outputs of the corresponding passband filters by a predetermined value so as to be oriented at a certain angle toward the quadrant side and the so-called second quadrant side;
first and second azimuth data forming units that analyze spatial frequencies based on the outputs of the first and second N delay circuits without determining their signs, and form and output azimuth data of incoming sound waves; first and second orientation selection circuits that extract and output data in a necessary range from corresponding outputs of the first and second orientation data forming sections; each output of the first and second orientation selection circuits; Combine and convert 1
The present invention is characterized by comprising: an azimuth synthesis circuit that forms and outputs two azimuth data;

[0019]

[Operation] Next, the operation of the orientation detecting device of the present invention constructed as described above will be explained with reference to FIG. FIG. 1 is an explanatory diagram of the principle of orientation synthesis according to the present invention. Figures 1(a) and (c) are
The relationship between the arrangement direction of the receiver array and the phasing plane formed by the first and second N delay circuits is shown. If the normal direction to the arrangement direction of the receiver array is 0° azimuth, the left side of the arrangement direction is -90° azimuth, and the right side is +90° azimuth, then the range from 0° to +90° is the so-called azimuth angle. 0° to -9 in one quadrant
The range of 0° is the so-called second quadrant. In addition, the first and second
Each of the azimuth data forming units analyzes the spatial frequency by, for example, the MEM method.

The first N delay circuits are, for example, shown in FIG.
), the output of the corresponding passband filter is adjusted so that the phasing surface is oriented at a certain angle (for example, +45°) from the normal direction of the receiver array toward the so-called first quadrant side. Delay by a predetermined value. -45°~0° range is D, 0°~
C for the range of +45°, B for the range of +45° to +90°,
If the range from +90° to the back side is A, the corresponding first
The MEM processing result in the orientation data forming section is shown in FIG. 1(b). In other words, if the normal direction of the phasing surface is 0° and the right side is 90°, the arrangement direction of the receiver array is 45°, but since the sign of the spatial frequency is ignored, it is 0°. The range from 45° to 45° is B+C, and the range from 45° to 90° is A+D. Here, since A is the rear area of the receiver array, there is no signal, and A+D is only the signal of D.

Further, as shown in FIG. 1(c), the second N delay circuits have phasing surfaces facing at a certain angle (for example, toward the so-called second quadrant) from the normal direction of the receiver array. -45
°) Delay the output of the corresponding passband filter by a predetermined value so that it faces in the tilted direction. -90° range from the back side is D', -90° to -45° range is C', -45° to 0
Assuming that the range of degrees is B' and the range of 0 degrees to +45 degrees is A', the corresponding MEM processing results in the second orientation data forming section are shown in FIG. 1(d). In other words, if the normal direction of the phasing surface is 0° and the right side is 90°, the arrangement direction of the receiver array is 45°, but since the sign of the spatial frequency is ignored, it is 0°. ~45° range is B'+C',
The range from 45° to 90° is A'+D'. Here, D
′ is the back area of the receiver array, so there is no signal;
A'+D' is only the signal of A'.

Next, the first azimuth selection circuit selects a range D (from 45° to 90°) of the output of the first azimuth data forming section.
The second azimuth selection circuit extracts the data in FIG.
Data in the 90° range A' (FIG. 1(d)) is extracted.

Then, as shown in FIG. 1(e), the azimuth synthesis circuit converts and sets the output of the first azimuth selection circuit (data in range D) to a range of -45° to 0°, The output of the azimuth selection circuit (data in range A') is converted and set to a range of 0° to +45°, and one azimuth data is formed and output.

Thus, according to the present invention, in a system that uses a method that does not determine the sign of the frequency for spatial frequency analysis, when the direction of arrival of the sound wave is in the so-called direction with respect to the normal direction to the arrangement direction of the receiver array, It becomes possible to determine whether it is on the first quadrant side or the so-called second quadrant side.

[0025]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows an orientation detection device according to an embodiment of the present invention. In the present invention, N bandpass filters (BPF) 2
At the subsequent stage, N delay circuits 3a (3b), data latch circuits 4a (4b), frequency analysis circuits 5a (5b), spatial frequency/direction conversion circuits 6a (6b), and direction selection circuits 7.
A (7b) is provided to make it into two systems, and further an azimuth synthesis circuit 8
is provided.

FIG. 3 shows how N delay circuits 3a (3b) form a phasing surface. Now, assuming that the normal direction to the array direction of the receiver 1 is azimuth 0°, the right side of the array direction is the plus (+) direction, and the left side is the minus (-) direction, then N Each of the delay circuits 3a delays the output of the corresponding passband filter by a predetermined value so that the phasing surface faces in a direction tilted by, for example, +45 degrees to the positive side from the normal direction of the receiver array. - On the other hand, the N delay circuits 3b have their phasing planes on the negative side from the normal direction of the receiver array, for example -45
The output of the corresponding passband filter is delayed by a predetermined value so that it faces in the tilted direction.

The data latch circuit 4a (4b) to the spatial frequency/azimuth conversion circuit 6a (6b) is the same azimuth data forming circuit as the conventional one, but the frequency analysis circuit 5a (5)
In b), the spatial frequency is analyzed by a method that does not discriminate its sign (for example, the MEM method). Therefore, Fig. 4(c)
), the normal direction of the phasing surface is 0°, and the right side is 90°.
If it is 0°, then the arrangement direction of the receiver array is 45°, but since the sign of the spatial frequency is ignored, the result of frequency analysis (MEM) is within the range of 90° if both are 0° (Fig. The part indicated by the middle diagonal line). Here, Figure 1
As explained above, data within the range of 45° to 90° is true data. Data within the range of 0° to 90° is output from the spatial frequency/azimuth conversion circuit 6a (6b) to the azimuth selection circuit 7a (7b).

The azimuth selection circuit 7a (7b) selects data within the range of 45° to 90° from the input data and outputs them to the azimuth synthesis circuit 8, respectively.

As shown in FIG. 4(d), the azimuth synthesis circuit 8 outputs the selection data of the + system as an azimuth output in the range of 0° to -45°, and outputs the selection data of the - system as the azimuth output in the range of 0° to +45°. Conversion and synthesis are performed to output the azimuth within the range, and azimuth data from -45° to +45° is output.

Although the phasing surface is inclined at ±45°, it goes without saying that the inclination can be determined arbitrarily.

[0031]

[Effects of the Invention] As explained above, according to the azimuth detecting device of the present invention, the phasing surface is tilted in two directions by the two delay circuits, and azimuth data is formed using each phasing surface. Therefore, the azimuth data forming unit performs frequency analysis without performing sign discrimination, but it is determined whether the direction of arrival of the sound wave is on the so-called first quadrant side or on the so-called second quadrant side with respect to the normal direction to the array direction of the receiver array. This has the effect of making judgment possible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of orientation synthesis of the present invention.

FIG. 2 is a configuration block diagram of a direction detection device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of the operation of the delay circuit.

FIG. 4 is an explanatory diagram of operations after the orientation data forming section.

FIG. 5 is a configuration block diagram of a conventional direction detection device.

FIG. 6 is a diagram showing the relationship between the direction of arrival of a sound wave and the output of a receiver.

FIG. 7 is an explanatory diagram when frequency analysis is performed without frequency sign determination.

[Explanation of symbols]

1　Receiver 2 N bandpass filters 3a N delay circuits 3b N delay circuits 4a Data latch circuit 4b Data latch circuit 5a Frequency analysis circuit 5b Frequency analysis circuit 6a Spatial frequency/azimuth conversion circuit 6b Spatial frequency/azimuth conversion circuit 7a Direction selection circuit 7b Direction selection circuit 8 Orientation synthesis circuit

Claims (1)

[Claims] Claim 1: A receiver array in which N receivers for receiving incoming sound waves underwater are arranged in a straight line at equal intervals of 1/2 wavelength or less of the incoming sound waves; N receivers arranged for each receiver;
N passband filters are provided corresponding to each of the N passband filters, and the phasing surface is located on the so-called first quadrant side and the so-called so-called first quadrant side from the normal direction to the arrangement direction of the receiver array. first and second N delay circuits that delay the outputs of the corresponding passband filters by a predetermined value so as to face the two quadrants in directions inclined at a constant angle;
first and second azimuth data forming units that analyze the spatial frequency based on the outputs of each of the N delay circuits without determining its sign, form and output azimuth data of an incoming sound wave;
first and second orientation selection circuits that extract and output data in a necessary range from corresponding outputs of the first and second orientation data forming sections; each output of the first and second orientation selection circuits; An azimuth detection device comprising: an azimuth synthesis circuit for synthesizing and converting directional data to form and output one azimuth data;