JPH03242577A - Apparatus for detecting target position - Google Patents

Abstract

PURPOSE:To detect a position and moving speed of a target only with a single directional passive sonobuoy by catching a target sound with the passive sonobuoy and noticing change with time of its doppler frequency. CONSTITUTION:An underwater sound caught by a directional passive sonobuoy 1 is sent to a frequency analyzer 2, where it is converted from data of a time region into data of a frequency region and supplied to a target sound identifying unit 3. Phase information and level information of each wave receiver of the identified signal is sent to a target azimuth calculation unit 4, and frequency information of the identified signal is sent to a sound source distance.moving speed calculation unit 5. The target azimuth calculation unit 4 calculates the azimuth of the target from a ratio of outputs of two directional wave receivers located perpendicular to each other and from a phase relation among outputs of two directional wave receivers and one non-directional wave receiver. The sound source distance.moving speed calculating unit 5 calculates a distance to the sound source and moving speed of the sound source so that the sound source is located by using the result of the target azimuth calculation unit 4 combined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a target position detection device, and particularly to a directional 771
The present invention relates to a target position detection device that detects the position of a moving underwater sound source using 41 units.

[Conventional technology]

Conventionally, this type of target position detection device drops a large number of sonobuoys from an aircraft carrying an observer into a search area on the sea surface, converts the underwater sounds received by the sonobuoys into radio signals, and transmits them to aircraft flying nearby. , the aircraft receives this, processes the signal, and detects the target position. In this case, an active sonobuoy is used as the sonobuoy, or two or more fingers are used. However, the disadvantage is that the target senses the sound and retreats to an area where the sound waves cannot reach.

In addition, directional passive sonobuoys require a structure with multiple directivity for target detection and an omnidirectional microphone for determining the quadrant of the detected target, so they are expensive and cannot be used in operational situations where a large number of them are used. The disadvantage is that the cost is excessive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a target position detection device capable of detecting a target position using a single directional sonobuoy, in order to eliminate the above-mentioned drawbacks.

[Means to solve the problem]

The target position detection device of the present invention has two
one passive sonobuoy equipped with I directional receivers and I swallow directional receivers, a frequency analyzer that analyzes the frequency of underwater sound signals captured by the passive sonobuoy, and the frequency analyzer A target sound identification unit identifies the characteristic sound frequency of the target sound source based on the analysis results of and a sound source distance and moving speed calculating section that calculates the distance between the sonobuoy and the sound source and the moving speed of the sound source from the frequency of the target sound undergoing Doppler shift.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. The configuration of the embodiment shown in FIG. 1 includes a directional passive sonobuoy 1. A frequency analysis section 22 that performs frequency analysis of the underwater sound supplied from the passive sonobuoy 1.A target sound identification section 3 that identifies the characteristic sound frequency of the target sound source from the frequency analysis result of the frequency analysis section 2. A target azimuth calculating section 4 that calculates the direction of the target by utilizing the fact that the level of the signal specified by the target sound specifying section 3 differs depending on the directional receiver. The directional passive sonobuoy 1 is equipped with a sound source distance/moving speed calculating section 5 that calculates the distance and moving speed of the target sound source based on the history of Doppler transition of the frequency specified by the target sound specifying section 3. Everything else is carried on board the receiving aircraft.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

The underwater sound captured by the directional passive sonobuoy 1 is sent to the aircraft-mounted frequency analyzer 2 using radio waves in the VHF band or the like, which are different for each receiver.

The signal from the passive sonobuoy I supplied to the frequency analysis section 2 is converted from time domain to frequency domain data using a Fourier transform process or the like in a frequency analysis circuit, and is supplied to the target sound identification section 3 .

The target sound identification unit 3 calculates the target direction based on the analysis result provided from the frequency analysis unit 2, and calculates the phase information and level information for each receiver of the identified signal that characterizes the sound signal emitted by the target. The frequency information of the specified signal is sent to the sound source distance/moving speed calculation section 5.

The target direction calculation unit 4 calculates the ratio of the outputs of two directional receivers arranged at right angles to each other and the phase of the outputs of the two directional receivers and one highly directional receiver. Calculate the direction of the target from the relationship.

The sound source distance/moving speed calculation unit 5 calculates the distance and movement of the target using the Doppler-displaced frequency as follows.

FIG. 2 is an explanatory diagram showing the details of determining the sound source distance and moving speed in the embodiment of FIG. 1. Passive sonobuoy 1
Suppose that a sound source passes a point at a distance r from the point in uniform linear motion with a velocity V. At that time, the frequency f(r') observed by the passive sonobuoy l is given by the following equation as a function of time t.

However, C is the speed of sound and fs is the sound source frequency.

When the time when the distance between the sonobuoy and the sound source becomes the minimum is set as t=0, the Macrolin expansion of equation (1) is obtained. However, f(N) represents the N-times differentiation of f depending on the likelihood.

On the other hand, if we consider approximating the 1=0 neighborhood of the observed frequency with an N-th degree polynomial and apply the least squares method, f (t) = a + βt - 1 rt2 + δt3 + song... + 1πtN unknowns are You are asked to do so.

...(3) The coefficients of each term are determined.

Comparing the coefficients of equations (2) and (3), f(0)=α
・・・・・・・・・・・・(4-1) f11+(0
)=β ・・・・・・・・・・・・(4-2)f”
(0)=2γ ・・・・・・・・・・・・(4-3)
f ”(0) = 6δ・・・・・・・・・・・・(
4-4).

Also, when actually calculating the coefficients of equation (2) up to the third-order term, f (0) = f s ・・・・・・・・・
・・・(5-1) C f”(0)=0 ・・・・・・・・・・・・
・It becomes (5-3).

(4-1), (4-2), (4-4) and (51),
From the relationship of equations (5-2) and (5-4), finally fs-α In this way, the sound source distance/moving speed calculation unit 5 knows the distance to the sound source and the moving speed of the sound source, and calculates the target direction. Part 4
According to the present invention, the position of the sound source can be determined by the passive sonobuoy having two directional receivers and one pyrodirectional receiver arranged at right angles to each other, as described above. By capturing the target sound and focusing on the temporal changes in its Doppler frequency, it is possible to create a target position detection device that can detect the target position and movement speed using only a single directional passive sonobuoy. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the details of determining the sound source distance and moving speed in the embodiment of FIG. 1. 1... Directional passive sonobuoy, 2...
...Frequency analysis section, 3...Target sound identification section, 4.
...Target direction 31 calculation unit, 5...Sound source distance/moving speed calculation unit.

Claims (1)

[Claims] one passive sonobuoy equipped with two directional receivers and one omnidirectional receiver arranged at right angles to each other; and a frequency analysis section that analyzes the frequency of underwater sound signals captured by the passive sonobuoy. a target sound identification unit that identifies the characteristic sound frequency of the target sound source from the analysis result of the frequency analysis unit; and a target sound identification unit that identifies the characteristic sound frequency of the target sound source from the analysis result of the frequency analysis unit; a target azimuth calculation section that calculates the direction of the target based on the level ratio; and a sound source distance/moving speed calculation section that calculates the distance between the sonobuoy and the sound source and the moving speed of the sound source from the frequency of the target sound undergoing Doppler shift. A target position detection device comprising: