JPH05302970A - Passive sonar apparatus - Google Patents

Abstract

PURPOSE:To automatically control the cardioid directivity characteristic of the title apparatus. CONSTITUTION:An underwater sound signal 101 from a hydrophone is cardioid- processed by means of a cardioid processing part 1; its frequency spectrum is analyzed by means of a frequency analysis part 2; only frequency spectrum data 103 which is larger than a threshold value 110 is extracted as target data 104 by means of an automatic signal detection part 3. A target classification part 4 compares sample frequency data 109 with the data 104; the coincidence data 104 is used as classification data 105. An average direction computation part 5 supplies, to a cardioid control part 6, average direction data 106 which has calculated the average direction of a plurality of classification data 105; the control part 6 controls a cardioid directivity characteristic to the direction of the direction data 106.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive sonar device, and more particularly to a passive sonar device having a function of automatically controlling a cardioid directional characteristic.

[0002]

2. Description of the Related Art In a conventional passive sonar device of this type, hydrophone means arranged in water have OMNI hydrophones having omnidirectional characteristics, NS hydrophones having directional characteristics in the north-south direction, and directional characteristics in the east-west direction. With E
Underwater sound from the underwater target through W Hydrophone,
This underwater sound is converted into an underwater sound signal and transmitted by means of radio waves or the like to a frequency analysis device mounted on an aircraft or the like placed in the air. This underwater acoustic signal
By the cardioid processing means in the frequency analyzer,
It is converted into cardioid processed data having electrical cardioid directional characteristics. The cardioid processed data is provided to the frequency analysis means. The frequency analysis means frequency-analyzes the cardioid processed data to generate frequency spectrum data, and the frequency analysis data is displayed on the display means and supplied to the target detection means.
The target detecting means extracts only frequency spectrum data larger than a predetermined threshold value from the frequency spectrum data as target data. The target classification means compares the target data with the sample frequency data set for each underwater target, and classifies the underwater target that generated the target data.

The principle of synthesizing cardioid directional characteristics in a passive sonar device will be described below with reference to the block diagram of FIG.

Hydrophone section 7 of the passive sonar device
Is an OMNI hydrophone 73 having omnidirectional characteristics, an NS hydrophone 71 having directional characteristics in the north-south direction, and an EW hydrophone 72 having directional characteristics in the east-west direction.
1a, 101b and 101c. As described above, the underwater acoustic signals 101a to 101c are converted into radio waves by the transmitter of the hydrophone unit 7 (not shown), and the radio waves are baseband underwater acoustic signals by the receiver of the frequency analyzer 10 (not shown). 101
It is reconverted to a to 101c and input to the cardioid processing unit 1 of the frequency conversion device 10. Underwater acoustic signal 1
01a and 101b are multiplied by Cos α and Sin α, which are direction data input from the operator by multipliers 11 and 12, respectively, and then added by adder 13
Is added to the underwater acoustic signal 101c. The output of the adder 13 is the Figure 8 (figure 8) data 206.
Represents the directivity characteristic of the figure 8 characteristic. Figu
By adding the re8 data 206 and the underwater acoustic signal 101c from the OMNI hydrophone 73 by the adder 14, the cardioid processed data 102 having the heart-shaped cardioid directional characteristic can be obtained. This data 1
02 is displayed on the cardioid processing unit 1 and is also sent to the frequency analysis unit 2 for frequency spectrum analysis to generate frequency spectrum data 103. The frequency analysis unit 2 also sends display data 108 based on the frequency spectrum data 103, and a display unit (not shown) follows the display data 108 and outputs the underwater acoustic signals 101a to 10a of the cardioid processed results.
The frequency spectrum analysis result of 1c is displayed on the display.

Next, the principle of synthesizing the above cardioid directional characteristics will be described using mathematical expressions.

Underwater acoustic signal 101a from NS hydrophone 71, underwater acoustic signal 1 from EW hydrophone 72
01b and the underwater acoustic signal 101c from the OMNI hydrophone 73 are defined by the following equations (1) to (3).
However, (theta) is the direction which receives the underwater sound of each hydrophone 71-73, and A (t) is each hydrophone 7 at the time t.
It represents the intensity of the normalized underwater sound received by 1-73.

Underwater acoustic signal 101a = A (t) Cos θ = R (1) Underwater acoustic signal 101b = A (t) Sin θ = S (2) Underwater acoustic signal 101c = A (t) = T (3) When the underwater acoustic signals R and S obtained by the hydrophones 71 and 72 are multiplied by azimuth data Cosα and Sinα that determine the directional characteristics, respectively, and addition is performed, Fi-gur
The e8 data 206 is obtained.

Data 206 = R · Cosα + S · Sinα = A (t) Cosθ · Cosα + A (t) Sinθ · Sinα = A (t) (Cosθ · Cosα + Sinθ · Sinα) = A (t) Cos (θ−α) ( 4) Figure8 data 206 and underwater acoustic signal 101c
The cardioid processed data 102 is obtained by adding (T) and.

Data 102 = Figure8 data 206 + underwater acoustic signal 101c = A (t) Cos (θ−α) + A (t) = A (t) {1 + Cos (θ−α)} (5) Equation (5) is , Θ = α (the receiving azimuth θ of the hydrophones 71 to 73 matches the azimuth data α), 2A
(T), and the magnitude A of the original underwater acoustic signal 101c
It has twice the gain of (t). On the other hand, when θ = α + π (the reception azimuth θ of the hydrophones 71 to 73 is opposite to the azimuth data α), the value is 0. Thus, the expression (5) shows the heart-shaped cardioid directional characteristic.

Here, the control of the cardioid directivity of the frequency analyzer 10 described above is manually performed by the operator in the cardioid processing unit 1 by using the azimuth data Cos α and Si.
nα was input, and control was performed so that the gain peak of the cardioid directional characteristic was in the angle α direction.

[0011]

In this conventional passive sonobuoy frequency analyzer, the operator analyzes the frequency spectrum data on the display means and manually confirms the above-mentioned data that can be recognized as an underwater target, and then manually operates the cardioid directional characteristic. Therefore, there is a problem that detection of an underwater target, particularly initial detection is delayed when a signal that can be clearly confirmed as the target is not displayed on the display means.

[0012]

The passive sonar device of the present invention is an underwater target through an OMNI hydrophone having omnidirectional characteristics, an NS hydrophone having directional characteristics in the north-south direction, and an EW hydrophone having directional characteristics in the east-west direction. Hydrophone means for receiving the underwater sound from the underwater sound and converting and transmitting this underwater sound signal, and cardioid processed data having electrical cardioid directional characteristics in response to the underwater sound signal from the hydrophone means. Generated cardioid processing means, frequency analysis means for frequency-analyzing the cardioid processing data to generate frequency spectrum data, target detection means for receiving the frequency spectrum data and extracting frequency spectrum data larger than a predetermined threshold value, The extracted frequency spectrum data In a passive sonar device comprising a target categorizing means for comparing the sampling frequency data set for each underwater target and outputting the extracted frequency spectrum data matching the sample frequency data as categorized data of the underwater target, The passive sonar device, further, azimuth calculation means for calculating the reception azimuth of all of these classification data from the classification data, an average azimuth calculation means for calculating an average of all the reception azimuths to generate an average reception azimuth, And a cardioid azimuth control means for controlling the cardioid processing means so that the gain peak of the cardioid directional characteristic is in the direction of the average reception azimuth.

[0013]

The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention.

This passive sonar device includes a hydrophone section 7, a cardioid processing unit, a cardioid processing unit, a frequency analyzing unit, a display unit, a target detecting unit and a target classifying unit of the conventional passive sonar unit. It includes a unit 1, a frequency analysis unit 2, a display unit 8, an automatic signal detection unit 3, and a target classification unit 4. The hydrophone unit 7 receives the underwater sound from the underwater target, and receives the underwater sound signal 101a-
An underwater acoustic signal 101 consisting of 101c is generated. Also,
Similar to the conventional passive sonar apparatus, the cardioid processing unit 1 produces the cardioid processed data 102, the frequency analysis unit 2 produces the frequency spectrum data 103, and the display unit 8 produces the display data 108 for displaying the frequency spectrum data 103. The signal automatic detection unit 3 is
The frequency spectrum data 103 is compared with a predetermined threshold 110, and the frequency spectrum data 104 having a level higher than the threshold 110 is output as the target data 104. The target categorization unit 4 compares the target data 104 with the sample frequency data 109 set for each underwater target, classifies only the target data 104 that matches the two as an underwater target, and classifies the classified target data 104. It is output as the classification data 105.

The classification data 105 is supplied to the average azimuth calculation unit 5, and the average azimuth calculation unit 5 calculates the reception azimuth for all of the cardioid-processed classification data 105 and further calculates the average of the calculated reception azimuths. Is calculated to generate average reception direction data 106. The cardioid control unit 6 controls the cardioid processing unit 1 by setting the azimuth angle data so that the gain peak of the cardioid directional characteristic is in the direction of the average reception azimuth indicated by the average reception azimuth data 106.

[0016]

As described above, according to the present invention, the average azimuth obtained from this data is calculated from the classification data of a plurality of underwater targets, and the cardioid directional characteristic is automatically controlled in the direction of this average azimuth. Therefore, there is an effect that the peak gain of the cardioid directional characteristic can be quickly directed toward the underwater target, and the target detection can be performed quickly.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a principle of combining cardioid directional characteristics in a passive sonar device.

[Explanation of symbols]

 1 Cardioid processing unit 2 Frequency analysis unit 3 Signal automatic detection unit 4 Target classification unit 5 Average direction calculation unit 6 Cardioid control unit 7 Hydrophone unit 8 Display unit 11, 12 Multiplier 13, 14 Adder 71 NS Hydrophone 72 EW Hydro Hong 73 OMNI Hydrophone

Claims (2)

[Claims] 1. An underwater sound from an underwater target is received through an OMNI hydrophone having omnidirectional characteristics, an NS hydrophone having directional characteristics in the north-south direction, and an EW hydrophone having directional characteristics in the east-west direction. Hydrophone means for converting and transmitting the signal, cardioid processing means for generating cardioid processed data having an electrical cardioid directional characteristic in response to the underwater acoustic signal from the hydrophone means, and frequency of the cardioid processed data. Frequency analysis means for analyzing to generate frequency spectrum data, target detection means for receiving the frequency spectrum data and extracting frequency spectrum data larger than a predetermined threshold, and for each of the extracted frequency spectrum data and underwater target Sample frequency data set In the passive sonar device comprising a target categorizing unit that outputs the extracted frequency spectrum data that matches the sample frequency data by comparing the sample frequency data with each other as the underwater target categorizing data, the passive sonar device is further provided from the categorized data. Azimuth calculation means for calculating the reception azimuth of all of these classification data, an average azimuth calculation means for calculating an average of all the reception azimuths to generate an average reception azimuth, and a direction of the cardioid directional characteristic in the direction of the average reception azimuth. A passive sonar device comprising: a cardioid azimuth control means for controlling the cardioid processing means so that a gain peak is reached. 2. The cardioid processing means comprises:
A first multiplier that multiplies the underwater acoustic signal from the S hydrophone by the cosine term of the azimuth data α, and a second multiplier that multiplies the underwater acoustic signal from the EW hydrophone by the sine term of the azimuth data α. , A first adder for adding the first and second multipliers to produce figure 8 data, a hydroacoustic signal from the OMNI hydrophone and the figure 8 data are added. A second adder for generating the cardioid processing data, and the cardioid control means includes means for supplying the average reception azimuth as the azimuth angle data α to the cardioid processing means. 1. The passive sonar device according to 1.