JP2785566B2 - Passive sonar device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used for a passive sonar device. In particular, the present invention relates to an underwater object detection circuit that receives a sound generated by an underwater object and detects the underwater object based on the loudness of the sound.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional receiver 1 receives a sound generated by an underwater object 9 and converts the sound into an electric signal.
A detection circuit 10 for detecting an output signal of the receiver 1 and outputting a detection signal, and a detection circuit 11 for verifying the magnitude of the detection output signal and outputting an underwater object detection signal. FIG.
Is the operation principle of the operation circuit of the underwater object detection circuit of the conventional passive sonar device. FIG. 4A is a spectrum of a sound wave generated by the underwater object 9. FIG. 4B shows the receiver 1
In the drawing, E indicates the detection level of the detection circuit 10, and TH indicates the threshold level of the detection circuit 11. In the case of FIG.
<TH, and the detection circuit 11 does not output the underwater object detection signal. FIG. 4C shows the spectrum of the output signal of the receiver 1 as in FIG. In this case, E> TH, and the detection circuit 11 outputs an underwater object detection signal.

[0003]

In such a conventional example, the level of the output signal of the receiver is detected as the total energy of an arbitrary frequency band. The level of E increases when the spectrum of the output signal of the device 1 is mixed with a particularly high level of noise,
There is a disadvantage that E> TH and the detection circuit 11 outputs an underwater object detection signal.

An object of the present invention is to provide a passive sonar device which eliminates such disadvantages and has means for preventing erroneous recognition of an underwater object.

[0005]

SUMMARY OF THE INVENTION The present invention provides a receiver for receiving a sound generated by an underwater object and converting the sound into an electric signal, and processing the electric signal converted by the receiver to obtain the underwater. A passive sonar device comprising: an underwater object detection unit that detects the presence of an object; wherein the underwater object detection unit is configured to resolve a frequency band of the electric signal converted by the receiver into a plurality of narrow frequency bands. A decomposition circuit, a detection circuit that detects each signal level in the narrow frequency band decomposed by the frequency decomposition circuit to generate a detection signal, and a switch circuit one of which is connected to an output side of the detection circuit, An average value calculation circuit connected to the other side of the switch circuit and calculating an average value level of a detection signal generated by a detection circuit supplied by a closed state of the switch circuit; A difference calculation circuit for calculating a difference value between the level of the wave signal and the average value level generated by the average value calculation circuit; and when the difference value calculated by the difference calculation circuit exceeds a predetermined difference value, A switch control circuit that opens a switch circuit, one of which is connected to the output side of the detection circuit that has provided the detection signal to the difference calculation circuit, and an output level of the average value calculation circuit that is tested to obtain an underwater object detection signal. And a detecting circuit for generating.

[0006]

The output signal of the receiver is decomposed into a plurality of narrow frequency bands, detected for each narrow frequency band, and applied to an average value calculation circuit through a switch circuit, where the detection output for each narrower frequency band is obtained. The average value is calculated, and the difference between the average value and the detection value for each narrow frequency band is calculated. If the difference value is equal to or greater than the predetermined difference value, the corresponding switch circuit is turned off to calculate the characteristic high-spectrum noise. This prevents input to the circuit and prevents erroneous output of the underwater object detection signal.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of this embodiment. In this embodiment, as shown in FIG. 1, a receiver 1 that receives a sound generated by an underwater object 9 and converts the sound into an electric signal, and processes the electric signal converted by the receiver 1 Underwater object detection means for detecting the presence of the underwater object, and as a characteristic feature of the present invention, the underwater object detection means is capable of converting the frequency band of the electric signal converted by the receiver 1 into a plurality of frequency bands. A frequency decomposition circuit 2 for decomposing into a narrow frequency band, a detection circuit 3 for detecting each signal level in the narrow frequency band decomposed by the frequency decomposition circuit 2 to generate a detection signal, and an output side of the detection circuit 3 And a mean value for calculating an average value level of the detection signal generated by the detection circuit 3 connected to the other end of the switch circuit 6 and supplied by the closed state of the switch circuit. Calculation circuit 4 and detection A difference calculation circuit 5 for calculating a difference value between the level of the detection signal generated in the path 3 and the average value level generated by the average value calculation circuit 4, and a difference value calculated by the difference calculation circuit 5 is a predetermined value. A switch control circuit 7 that opens a switch circuit 6 connected to one of the output sides of a detection circuit that has supplied a detection signal to the difference calculation circuit 5 when the difference value exceeds the average value calculation circuit 5, and an average value calculation circuit 4 And a detection circuit 8 for testing the output level of the underwater object to generate an underwater object detection signal.

Next, the operation of this embodiment will be described. FIG.
FIG. 2 is a signal explanatory diagram of each part of the embodiment shown in FIG. The sound generated by the underwater object 9 is received by the receiver 1 and converted into an electric signal. A case where a particularly high-level noise is mixed in the spectrum of the output signal of the receiver 1 as in the state of FIG. An output signal of the receiver 1 is decomposed by a frequency decomposition circuit 2 into an arbitrary number of narrow frequency bands. Each output of the frequency decomposition circuit 2 is an arbitrary number of detection circuits 3
Is detected for every arbitrary number of narrow frequency bands. The switch circuits 6 connected to the output of the detection circuit 3 are all in a contact state initially. When the switch circuit 6 is connected, the average value calculation circuit 4 calculates the average value of the connected detection output signals. E in FIG. 2 (a)
Indicates the average value of the detection output signal. T in FIG. 2 (a)
H indicates the threshold level of the detection circuit 8 that tests the magnitude of the output level of the average value calculation circuit 4 and outputs an underwater object detection signal. In this case, E> TH, and the detection circuit 8 outputs an underwater object detection signal. The difference calculation circuit 5 calculates the difference between the detection output signal at the location connected by the switch circuit 6 and the output average value of the average value calculation circuit 4. If the output of the difference calculation circuit 5 is equal to or larger than a preset difference value, the output of the detection circuit 3 is turned off by the switch control circuit 7. The switch circuit 6 connected to the output of the narrow-band detection circuit 3 including the characteristic high-level noise spectrum of FIG.
A characteristic high-level noise spectrum like the spectrum in FIG. 2B can be deleted. E in FIG. 2B indicates the average value of the detection output signal. T in FIG. 2 (b)
H indicates the threshold level of the detection circuit 8 that tests the magnitude of the output level of the average value calculation circuit 4 and outputs an underwater object detection signal. In this case, E <TH, and the detection circuit 8 does not output the underwater object detection signal.

[0009]

As described above, according to the present invention, even when the spectrum of the output signal of the receiver contains a particularly high level of noise, the average level of the signal can be accurately calculated by removing the noise. This has the effect of preventing erroneous output of the underwater object detection signal.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing waveforms of signals of respective parts of the circuit shown in FIG. 1;

FIG. 3 is a block diagram showing the configuration of a conventional example.

FIG. 4 is a diagram showing waveforms of signals of respective parts of the circuit shown in FIG. 4;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 receiver 2 frequency decomposition circuit 3 detection circuit 4 average value calculation circuit 5 difference calculation circuit 6 switch circuit 7 switch control circuit 8 detection circuit 9 underwater object 10 detection circuit 11 detection circuit

Claims (1)

(57) [Claims] 1. An underwater object for receiving a sound generated by an underwater object and converting the sound into an electric signal, and processing the electric signal converted by the receiver to detect the presence of the underwater object. A passive sonar device provided with a detection means, wherein the underwater object detection means comprises: a frequency decomposition circuit for decomposing a frequency band of the electric signal converted by the receiver into a plurality of narrow frequency bands; A detection circuit that detects each signal level of the narrow frequency band decomposed by the above and generates a detection signal; a switch circuit having one connected to an output side of the detection circuit; and a switch circuit connected to the other of the switch circuit. An average value calculation circuit that calculates an average value level of a detection signal generated by a detection circuit supplied by a closed state of the switch circuit; and a level of the detection signal generated by the detection circuit. A difference calculation circuit for calculating a difference value between the average value level generated by the average value calculation circuit, and a detection signal when the difference value calculated by the difference calculation circuit exceeds a predetermined difference value. A switch control circuit that opens a switch circuit, one of which is connected to the output side of the detection circuit provided with the detection circuit, and a detection circuit that tests the output level of the average value calculation circuit and generates an underwater object detection signal. A passive sonar device comprising: