JPH0627799B2 - Passive sonar device - Google Patents

Description

The present invention relates to a passive sonar device, and more particularly to a passive sonar device equipped with an omnidirectional receiver.

[Conventional technology]

Conventionally, a passive sonar apparatus has a plurality of omnidirectional receivers (hereinafter, simply referred to as “sensors”) arranged in a distributed manner so that sound waves from a target can be captured. Then, in this apparatus, the frequency of each sensor output is analyzed, and the operator finds the frequency spectrum of the target from the display of the analysis result and determines the detection of the target.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, only the presence in a vague area centered on each sensor can be confirmed, and the positional relationship between the target object and each sensor (azimuth) There was a disadvantage that it was not possible to accurately capture.

[Object of the Invention]

An object of the present invention is to improve the inconveniences of the above conventional example,
In particular, it is an object of the present invention to provide a passive sonar device capable of calculating and displaying a position and a trajectory of a target object and limiting an area where the target object exists based on the calculated and displayed position.

[Means for solving problems]

In the present invention, in a passive sonar device including a plurality of sensors that are distributed at predetermined positions to receive sound waves from a target object, and a frequency analysis circuit that calculates a frequency spectrum from sound waves received by the sensors, The data display means for storing and displaying the output of the analysis circuit is provided, and the closest time t of the target object, the detection frequency f ₀ , and the doppler are obtained from the frequency spectrum of the received sound waves stored and displayed on the data display means. A target detection calculation circuit for performing a predetermined calculation based on the shift Δf, the Doppler shift change time Δt, etc. to calculate the closest distance R of the target to each sensor, the passing speed V, and the passing trajectory, and the target detection calculation circuit. And a target object display means for displaying the output of the. This aims to achieve the above-mentioned object.

Example of Invention

An embodiment of the present invention will be described below with reference to FIGS.

The embodiment shown in FIG. 1 includes eight sensors 1, 1, ... As omnidirectional receivers, which are distributed at appropriate positions and receive sound waves from a target object. And a frequency analysis circuit 2 for calculating a frequency spectrum from a sound wave.

The output of the frequency analysis circuit 2 is sent to the data display means 3. The data display means 3 has a function of storing and displaying the frequency spectrum sent from the frequency analysis circuit 2.

The data display means 3 is provided with the first arithmetic circuit 4. Then, the operator compares the frequency spectrum displayed on the data display unit 3 with the frequency spectrum of the target object converted into a canalog, detects the target object, and specifies (inputs) the target frequency.

The first arithmetic circuit 4 performs tracking on the target frequency designated above in the frequency spectrum stored in the data display means 3, and then calculates various quantities related to Doppler shift as shown in FIG. Calculate by

・ Detection frequency: f ₀ = (f _H + f _L ) / 2 ... Target frequency without Doppler (CPA) ・ Doppler shift: Δf = f _H -f _L・ Doppler shift change time: Δt = T _fL -T _fH ... f
Time required for changing from _H to f _L・ Time of closest approach: time when t ... f ₀ = Tf _{0 A} function of sending these results to the above-mentioned data display means 3 and storing them is provided.

The information of the closest approach time t, the detection frequency f ₀ , the Doppler shift Δf, and the Doppler shift change time Δt stored in the data display means 3 is transmitted via the information input circuit 5 to the second arithmetic circuit 6 as a target detection arithmetic circuit. Sent to. The second arithmetic circuit 6 has a function of calculating the closest approach distance R, the passing speed V and the passing locus of the target based on the information sent from the information input circuit 5. This second
The output of the arithmetic circuit 6 is displayed on the target display means 7.

Here, a part of the above-described embodiment will be described in more detail.

The data display means 3 has a function of storing and displaying the output of the frequency analysis circuit 2 as described above. In this case, the display method is FT display in which frequency (F) is set on the horizontal axis and time (T) is set on the vertical axis. The results analyzed by the frequency analysis circuit 2 for each sensor are displayed on the data display means 3 as FT.

The first arithmetic circuit 4 is a CPA (Closect Point of Aproach) of a target frequency designated by the operator based on the FT display data stored and displayed in the data display means 3; Point), that is, the closest approach time t, the detection frequency f _{0 at} that position, its Doppler shift Δf, and the change time Δ of the Doppler shift Δf.
It has a function of calculating t and. These various data are stored in the data display means 3 and are sent to the second arithmetic circuit 6 via the information input circuit 5 as described above.

The second arithmetic circuit 6 is adapted to calculate the passing speed V of the target object and the distance between the sensor position in CPA, that is, the closest distance R according to the following equation based on the sent data.

V = C · Δf / 2 · f 0 ...... However C is based on the acoustic velocity _{^{R = V 2 · f 0 /}} C · (Δf / Δt) ...... target display means 7, the above results in water, the target The existing position of is displayed as a circle with a radius R. When detected in one of the dispersed sensors 1, one circle becomes the existence line of the target object (see (1) in FIG. 3). If detected in two places, two circles will be displayed and the tangent line between the two circles will be 4
One of the books becomes the trajectory of the target. Also, of these four tangents, either the length of the tangent between the contact points with the circle and the V found by the formula and the two tangents that match from the time difference of CPA for the two sensors 1 are the target objects. The target object display means 7 is narrowed down as a passage locus of the target object (see FIG. 3).
Is displayed at.

The process of obtaining the tangent line that is the locus of passage of the target object is performed by the second arithmetic circuit 6. Further, when detected at three or more places, three or more circles are displayed as shown in FIG. 3 (3), and one tangent line connecting to all the circles is displayed as the trajectory of the target object. . The target of the circle contact is the sensor 1
The position in CPA which passed through is shown.

FIG. 2 shows that the target frequency spectrum changes in the vicinity of OPA for the sensor 1 due to the Doppler shift.

3 (1) to (3) show the limits of the target position appearing on the target display means 7 as described above.
Of these, FIG. 3 (1) shows an example in which the sensor is detected at one sensor position S1, and it is shown that it exists on the circumference of radius R1 at time t1 of CPA for the sensor position S1. Further, FIG. 3 (2) shows two sensor positions S1 and S2.
CPA for sensor position S1 in the case of being detected by
It exists on the circumference of R1 at time t1, and exists on the circumference of r2 at time t2 of CPA for the sensor position S2. Furthermore, as the passage trajectories of the target object, four tangential lines L ₁ , which match the passing speed of the target object and the distance between the contact points,
L ₂ , L ₁ ′ and L ₂ ′ are shown. Furthermore, FIG. 3 (3) shows 3
In the case of detection at sensor positions S1, S2, S3 at various locations,
Three circles are displayed in the same manner as described above, and one tangent line L ₃ tangent to the three circles is shown as the trajectory of the target object.

FIG. 4 shows another embodiment. The other embodiment shown in FIG. 4 is a simplified form of the embodiment shown in FIG.
The arithmetic circuit 4 and the information input circuit 5 are omitted, and instead of this, the input stage of the second arithmetic circuit 6 is equipped with information input means 5A such as a keyboard.

More specifically, the FT display data displayed on the data display means 3 is the Doppler shift Δf at the detection time f ₀ and the times t ₁ , t ₂ , t _{3 of} CPA by the operator.
And Doppler shift change time differences are Δt ₁ , Δt ₂ , Δt
₃ ... etc. Can be read. Then, each of the read data W is transferred from the information input means 5A to the second arithmetic circuit 6
It is designed to be input to. As a result, the same result as that of the embodiment shown in FIG. 1 can be obtained.

Other constitutions and effects are the same as those of the embodiment shown in FIG.

〔The invention's effect〕

As described above, according to the present invention, since the frequency spectrum of the target object analyzed from the received sound and the Doppler shift of this frequency spectrum are used, the position where the target object comes closest to the sensor is detected. This makes it easier to limit and display the change of the passing position, that is, the passing locus, by receiving and analyzing the signals from two or more sensors, which effectively makes the area where the target exists. It is possible to provide an excellent passive sonar device which can be limited and which has never existed before.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 to 3 (1) (2) (3) are explanatory views of the operation of FIG. 1, respectively.
FIG. 4 is a block diagram showing another embodiment. 1 ... Sensors as omnidirectional receivers, S1, S2, S
3 ... Sensor position, 2 ... Frequency analysis circuit, 3 ... Data display means, 4 ... First arithmetic circuit, 5 ... Information input circuit, 6 ... Second arithmetic circuit as target detection arithmetic circuit ,
7 ... Target display means, 5A ... Information input means.

Claims (1)

[Claims] 1. A plurality of omnidirectional receivers which are dispersedly arranged at predetermined positions to receive sound waves from a target, and a frequency analysis for calculating a frequency spectrum from the sound waves received by the omnidirectional receivers. In a passive sonar device including a circuit, a data display means for storing and displaying the output of the frequency analysis circuit is provided, and a target object obtained from the frequency spectrum of the received sound wave stored and displayed in the data display means is provided. A predetermined calculation is performed based on the closest approach time t, the detection frequency f ₀ , the Doppler shift Δf, the Doppler shift change time Δt, and the like,
The closest distance R of the target to each of the omnidirectional receivers,
A passive sonar device comprising a target detection calculation circuit for calculating a passage speed V and a passage trajectory, and a target display unit for displaying an output of the target detection calculation circuit.