JPH026378Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a passive sonar device, and more particularly to a target orientation detection device.

Conventionally, one method of determining the direction of arrival of a signal from a target in a passive sonar device is to detect the direction in which the target signal disappears due to the directivity in which the sensitivity drops sharply with respect to a specific direction, as shown in Figure 1 a and b. The so-called NULL method is known. The easiest way to obtain directivity as shown in Figure 1 a and b is to create a difference between the received signals from two receivers, but it is possible to
To obtain NULL directivity, the wavelength λ (=C/) is determined by the frequency of the received signal and the speed of sound C in water.
and the distance d between the two receivers is approximately d/λ.
There is a restriction that it is 0.4 or less. Note that FIG. 1b shows the characteristic obtained when the operation of the right receiver is delayed for a certain period of time and the difference between the two receivers is taken, and the NULL direction rotates.

In general, in passive sonar devices, the frequency band of the target signal is wide, so multiple receivers with known arrangement spacing are prepared in advance, and the combinations are determined according to the spectrum obtained by frequency analysis. By selecting one by one, various spacings d were taken and the quality of the spacings d was tested to select a receiver with the optimum spacing. However, in such a device, if there are many receivers to prepare,
The number of combinations to be selected is large, and it takes a considerable amount of time to obtain the optimum combination.The procedure is also complicated and selection errors occur.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional methods, and to easily and quickly select the optimal receiver from multiple receivers by simply specifying the target line spectrum frequency obtained through frequency analysis, etc. The object of the present invention is to provide a direction detection device that can reduce the negative phase of the operator and eliminate mistakes by selecting a combination and creating NULL directivity.

The present invention is composed of an input selection circuit for selecting a combination of signals from a group of receivers, a selection control circuit, and a phasing circuit for creating NULL directivity.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows an embodiment of the invention.

The target direction detection device of the present invention is composed of a receiver 1, an input selection circuit 2, a signal delay circuit 3, a subtraction circuit 4, and an input selection control circuit 5. The receiver group 1 converts the acoustic signal from the target into an electrical signal. Convert to These electrical signals are supplied to the input selection circuit 2. When the target frequency is specified by the operator, the input selection control circuit 5 calculates the wavelength λ determined by the frequency and the speed of sound C in water, and selects an interval d such that d/λ is about 0.1 to 0.4. The set of two receivers to have is determined and a selection signal is generated. This selection signal is supplied to the input selection circuit 2, and two receiver outputs are selected from the outputs of the receiver group. The output of one of the two is 3
n variable signals from -1 to 3-n are supplied to the delay circuits, and after a predetermined delay is given, n subtraction circuits from 4-1 to 4-n are used to connect the signals to the other signal. A difference signal is created. That is, the signal delay circuit 3 and the subtraction circuit 4 constitute a phasing circuit that generates directivity with different NULL directions from the outputs of the two receivers, as shown in FIGS. 1a and 1b.
The direction in which the phased output is minimized can be found by verifying the level of the target frequency using, for example, a spectrum analyzer.

In the embodiment shown in FIG. 2, the signal delay circuit 3 and the subtraction circuit 4 may be configured with a digital phasing circuit using a memory or the like by converting the outputs of the two selected receivers into digital data. It is possible. Furthermore, the input selection control circuit 5 can calculate the wavelength λ, etc. in advance, and create a table format using a read-only memory in which the combination of receivers can be determined from the frequency.

As explained above, the present invention has an input selection control circuit that specifies a frequency and outputs a signal to select the optimal combination of two receivers for that frequency. A set of two receivers can be automatically selected from the output signals of a plurality of receivers, reducing the negative phase burden on the operator and allowing for quick, error-free operation.

[Brief explanation of the drawing]

FIGS. 1a and 1b are diagrams showing an example of the directivity of the difference between dipoles formed by two receivers, and FIG. 2 is a block diagram showing an embodiment of the present invention. 1... Multiple receiver groups, 2... Input selection circuit, 3... n signal delay circuits, 4... n subtraction circuits, 5... input selection control circuit.

Claims (1)

[Scope of utility model registration request] In a target orientation detection device that selects a pair of receivers from a plurality of non-directional receivers arranged in a straight line and detects the target orientation based on the difference output of both receivers,
By specifying the frequency determined by frequency analysis of the received signal, the spacing between two receivers required to create the optimal directivity for this frequency signal is calculated, and the optimal one is selected from the receiver group. 1. A target direction detection device comprising a circuit that automatically selects a suitable combination.