JP2610315B2 - Passive sonar device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive sonar device, and more particularly to an omnidirectional receiver for analyzing the frequency of a target radiated noise to find and detect a characteristic frequency spectrum of a target. And to a passive sonar device of a distributed arrangement type.

[Prior art] Conventionally, as a method of limiting the position of a passive sonar device of this type, a target is focused on a Doppler shift at the time of a closest point of approach (CPA) of a target frequency spectrum when a sensor detects the target. The position line at the time of CPA was displayed.

[Problems to be Solved by the Invention] In the conventional passive sonar device described above, the sensor focuses on the Doppler shift of the target frequency spectrum at the time of CPA at the time of detection and displays the position line at the time of the target CPA. However, even when a target is detected, there is a drawback that only the position line of the target can be drawn only during CPA, and the position line cannot be displayed in real time.

[Means for Solving the Problems] The present invention has been made to solve the above problems.
As a solution, the present invention is directed to a non-directionally distributed receiver, a frequency analysis circuit for analyzing a reception frequency of the receiver, and a display for displaying an analysis result in the analysis circuit. A frequency tracking circuit for tracking a target frequency spectrum during target detection, an arithmetic circuit for calculating a target position line and a target position in real time from the Doppler shift amount of the target frequency spectrum, and displaying the target position line and the target position. And a display.

Example Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.
The outline will be described with reference to FIG.

The omnidirectional receiver is distributed and installed at an appropriate position in the sansay 1, and the sensor output is connected to the frequency analysis circuit 2.

The frequency analysis circuit 2 analyzes the frequency of each sensor output,
The analysis result is sent to the display 3.

The display 3 displays the frequency analysis result in FT (horizontal axis, frequency, vertical axis, time). The operator finds the target frequency spectrum from the FT display, and specifies the target tracking frequency using the input function of the display 3.

The frequency tracking circuit 4 tracks the target frequency spectrum specified above and outputs real-time Doppler frequency information to the arithmetic circuit 5.

The arithmetic circuit 5 calculates a target position line and a target position in real time from the Doppler shift amount of the target frequency spectrum.

That is, a plurality of sensors can be
If only one of the sensors detects a target, a straight line containing the target position can be specified. If two sensors 1,1 detect the target, an arc containing the target position can be specified. , 3
When the two sensors 1 and 1 detect the target, the position of the target itself can be specified.

First, a case where only one sensor 1 detects a target will be described.

Assuming that the frequency of the target detected by the sensor 1 is f ₁ when the target exists at a position before passing through the CAP, this frequency becomes By being expressed, Is expressed as As it can be calculated theta ₁ at this position.

Here, as shown in FIG. 2, θ ₁ is the angle of the sensor 1 with respect to the target course, C is the sound speed, V is the target speed, and f _0.
Is the frequency of the target when it is not hazy Doppler, the f ₀ and V used once value target is obtained when passing through the CPA.

If the target is located immediately before passing through the CPA, and the frequency of the target detected by the sensor 1 is f ₂ and the angle of the target 1 to the sensor 1 with respect to the course is θ ₂ , Likewise If the target is present in the _CPA, and the frequency of the target detected by the sensor 1 is f _CPA and the angle of the sensor 1 with respect to the target course is θ _CPA , It is expressed as

Since f ₀ is a value obtained once the target has passed the _CPA , f _CPA = f ₀ . It is expressed as

Thus, the angle θ with respect to the target course from the target frequency f (f ₁ , f ₂ ... F _CPA .
_{(Θ 1, θ 2 ... θ} CPA ...) The ability to calculate the angle _{θ (θ 1, θ 2 ...} θ CPA ...) with respect to the sensor 1 a straight line including the position of the target as a straight line which forms an identifiable in real time.

Next, a case where the two sensors 1, 1 detect a target will be described.

As shown in FIG. 3, when the sensor A and the sensor B simultaneously detect the target, assuming that the angle of the sensor A with respect to the path of the target is θ _A and the angle to the sensor B is θ _B , each of these angles is , As mentioned above, Than, Is expressed as Than, It is expressed as

Here, the angle θ _A to the sensor A with respect to the target course is
The angle theta _B and the range in which always satisfies the above equation to the sensor B, as shown in FIG. 3 (a), sensors A and B
Since the angle θ _A −θ _B sandwiching the azimuth line from is represented as an arc, the arc including the target position can be identified in real time by calculating the center and radius of the circle forming the arc. .

Next, a case where three sensors 1, 1 detect a target will be described.

In this case, as shown in FIG. 3 (b), when the angle to the sensor A with respect to the target course is θ _A , the angle to the sensor B is θ _B , and the angle to the sensor C is θ _C. Each of these angles is calculated in the same manner as described above, and the arc including the target position can be specified in real time by calculating the center and radius of a circle forming three arcs including the target position. .

Using the coordinates and radius of the center of the straight line or circle obtained by the arithmetic circuit 5 in this way, the display 6 displays the straight line or circular arc as a position line. Especially three or more sensors 1,1
, The displayed arcs intersect at one point, so that the target position and course can be specified.

Further, the display 6 can display the movement of the target in real time based on the arc data sent from the arithmetic circuit 5 every moment.

[Effects of the Invention] As described above, the passive sonar device of the present invention includes a non-directionally distributed receiver, a frequency analysis circuit for analyzing a reception frequency of the receiver, and the analysis circuit. A display for displaying the analysis result in, a frequency tracking circuit for tracking a target frequency spectrum during target detection, and an arithmetic circuit for calculating a target position line and a target position in real time from the Doppler shift amount of the target frequency spectrum, The target position line and the position and the course are tracked in real time by tracking the frequency spectrum of the target while multiple sensors are detecting the same target. It can be displayed and has the effect of limiting the position of the target.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a passive sonar device according to an embodiment of the present invention, FIG. 2 is a diagram showing a state of a Doppler shift of a target frequency spectrum from a positional relationship between a target course and a sensor, and FIG. a) and FIG. 3 (b) are diagrams showing position lines and target positions determined in simultaneous detection of a plurality of sensors. 1: Sensor, 2: Frequency analysis circuit 3: Display, 4: Frequency tracking circuit 5: Operation circuit, 6: Display

Claims (1)

(57) [Claims] 1. A plurality of omnidirectionally distributed receivers, a frequency analysis circuit for analyzing reception frequencies of the plurality of receivers, and an analysis result by the frequency analysis circuit are displayed. A display, a frequency tracking circuit that receives the output of the frequency analysis circuit and tracks a target frequency spectrum during target detection, and receives the output of the frequency tracking circuit and outputs a target frequency spectrum and a target speed when Doppler is not applied. An arithmetic circuit for calculating a target position line and a target position in real time from a Doppler shift amount of a target frequency spectrum in the plurality of receivers; and receiving the output of the arithmetic circuit to display the target position line and the target position. A passive sonar device comprising a display.