JPH0288984A - Active sonar device - Google Patents

Abstract

PURPOSE:To detect echo signals irrespective of the level of received signals by using a directivity synthesization circuit which forms two wave receiving means having different effective acoustic centers, phase difference detection circuit, high-pass filter, variance value circuit, variance value gate circuit, and gate width discrimination circuit. CONSTITUTION:This active sonar device is provided with a directivity synthesization circuit 4 which forms two wave receiving beams having different effective acoustic centers, phase difference detection circuit 9 which detects the phase difference between signals received by the two wave receiving beams, and high-pass filter 10. In addition, a variance value circuit 11 which measures the variance of the output value of a signal process circuit, variance value gate circuit 12 which discriminates whether or not a variance value exceeds a threshold level, and gate width discrimination circuit 13 which discriminates whether or not the interval of a variance value gate is longer than a fixed period are also provided to the sonar device. Therefore, echoes can be detected irrespective of the influence and level of surrounding noise.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to active sonar devices, particularly [Prior Art] Conventionally, this type of active sonar device detects a received signal, compares it with a threshold value, and determines a target. The operation was to detect.

FIG. 3 is a general configuration diagram of this type of active sonar device. FIGS. 4(a) to 4(c) are waveform diagrams illustrating the processing of a conventional active sonar device. Transmission circuit 3
amplifies the transmitted signal and transmits it from the transceiver 1 to the underwater sonar target 2 as a sound wave 120 through the switch 110. The echo ion 130 from the underwater sonar target 2 is converted from an acoustic signal to a reception signal 101 by the transducer 1 along with surrounding noise 140, and is amplified by the reception circuit 5 through the directional synthesis circuit 4 that forms a directional reception beam. , is band-limited by the reception processing circuit 7 and detected by the amplitude detection circuit 14. The detected signal 1401 is set to the threshold value 14 by the gate circuit 15.
11, and if it exceeds the threshold, gate signal 1501
Output. The detailed operation will be explained with reference to FIG.

FIG. 4(a) shows the operation when the received signal level is appropriate. Received signal 101 has noise 102 and echo 10
Contains 3. This is detected by the amplitude detection circuit 14 and is used as a detected signal 1401. Gate circuit 15 has threshold value 1411
Compared to this, 1504 (game) is output only during echo. On the other hand, FIG. 4(b) shows the operation when the received signal level is low. Although this case also includes noise 102 and echo 103, the detected signal 1401 has a threshold value of 1
Since it does not exceed 411, the gate does not output.

In addition, FIG. 4(C) shows the operation when the received signal level is high, and since the detected signal 1401 exceeds the threshold 1411 with respect to the noise 102, the gate 1504 due to the echo
and a gate 1505 due to noise is output.

[Problems to be solved by the invention] The conventional active sonar device described above detects the received signal and compares it with a threshold value, so it is not affected by the noise level and echo level existing in the surrounding area. It has the disadvantage that it is easily affected by the magnitude of the received signal level, such as false gates due to surrounding noise and failure to gate when the echo level is low.

[Means for Solving the Problems] The gist of the present invention is an active sonar device that detects a sonar target by emitting sound waves underwater and detecting echoes from the sonar target. A directional synthesis circuit that forms a wave beam, a phase difference detection circuit that detects the phase difference of the received signal between two received beams, a high-pass filter, and a dispersion value circuit that measures the dispersion of the signal processing circuit output value. , a dispersion value gate circuit that determines whether the dispersion value exceeds a threshold value, and a gate width determination circuit that determines whether the interval between the dispersion value gates is longer than a predetermined time.

[Example code] Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a waveform diagram illustrating the operation of one embodiment.

The transmission circuit 3 amplifies the transmission signal and sends it to the underwater sonar target 2 as a sound wave 120 from the transducer 1 through the switch 110.
will be sent to. Echo sound 1 from underwater sonar target 2
30 is converted from an acoustic signal into a received signal 101 by the transducer 1 along with surrounding noise 140. A received signal 101 from the transducer 1 is passed through a directional synthesis circuit 4 that forms two receiving beams with different acoustic centers, amplified by a receiving circuit 5.6, and band-limited by receiving processing circuits 7 and 8. The received processed signals 701 and 801 are input to the phase detection circuit 9, and the phase difference between the received processed signals 701 and 801 is outputted as a phase signal 901. The phase signal 901 is passed through a high-pass filter (
HPF) 1O removes the low frequency component, and the phase processed signal 1
It is input to the dispersion value circuit 11 as 001. The dispersion value circuit 11 stores the phase processed signals 1001 which are manually inputted one after another for a certain period of time, calculates the dispersion value sequentially, and outputs the dispersion value 101. The variance gate circuit 12 determines whether the variance is below the variance threshold 1102 and outputs the variance 1 direct gate signal 120.
Outputs 1. The gate width determination circuit 13 determines whether the variance value gate signal 1201 is gated for a certain period of time or more, and if it is gated for a certain period of time or more, the detection signal 13
Outputs 01. FIG. 5 shows a principle diagram explaining the principle of acoustic center and phase difference generation. The phase difference between the receiving beam having the acoustic center 16 and the receiving beam having the acoustic center 17 in FIG. 5 depending on the incident angle and the distance between the acoustic centers can be expressed as shown in equation (1).

△ dXf Equation 1) means that in the case of an echo signal whose incident angle is fixed, the phase difference φ is a constant value, and in the case of a noise signal whose direction is not fixed, it takes various values.

Hereinafter, the operation of one embodiment will be explained in detail using FIG. 2. The phase detection circuit 9 detects the phase difference between the received processed signals 701 and 801 and outputs a phase signal 901.

The phase signal 901 shows various values for noise and takes a constant value for echo. The phase signal 901 has a low frequency component removed by a high-pass filter 10, and is input to a dispersion value circuit as a phase processed signal 1001. In the dispersion value circuit, the data of the input phase processed signal 1001 is always stored for a time of Δt, and Δ is stored as the phase processed signal 1001 between
The variance value of 1 is calculated and the variance value 1101 is output. During the echo, the phase difference between the received processed signals 701 and 801 is constant, so the dispersion value is small and large in the noise portion. The dispersion value gate circuit 12 outputs a dispersion value gate signal 1201 when the dispersion value 1101 is equal to or less than the dispersion threshold value ]102. The gate width determination circuit I3 measures the width of the dispersion value gate, and if there is a gate width greater than a certain width (ΔW), a detection signal 1 is output.
301 is output. As described above, the present invention enables echo detection regardless of the magnitude of the noise level and echo level.

[Effect of the invention] As explained above, the present invention has two acoustic centers separated from each other.
By using a directional synthesis circuit that forms two received beams, a phase difference detection circuit, a high-pass filter, a dispersion value circuit, a dispersion value gate circuit, and a gate width determination circuit, echo signals can be detected regardless of the received signal level. It has a detectable effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an active sonar device according to an embodiment of the present invention, FIG. 2 is a waveform diagram explaining the processing operation of the embodiment, and FIG. 3 is a block diagram showing the configuration of a conventional active sonar device. Block diagram shown in FIGS. 4(a) to (C)
5 is a waveform diagram illustrating the processing of a conventional active sonar device, and FIG. 5 is a principle diagram illustrating the relationship between the acoustic center and the phase difference. 1 ・ ・ Φ l 10 @ 3 ・ ・ ・ 4 ・ ・ 5, 6 contest 7, 8 φ 9 ・ 1 11 ・ ・ l 2 ・ ・ 13・Fist 14 ・ ・ Transducer/receiver, switch, transmitter circuit, directivity Synthesis circuit, reception circuit, reception processing circuit, phase detection circuit, high-pass filter variance value circuit, variance value gate circuit, gate width determination circuit, amplitude detection circuit, 15 ・ ・ 16, 1 120 ・ 130 ・ 140 ・ 101 ・ 102 ・103 ・

Claims (1)

[Claims] This is an active sonar device that detects a sonar target by emitting sound waves into the water and detecting echoes from the sonar target, and includes a directional synthesis circuit that forms two receiving beams with different acoustic centers, and two receiving beams. A phase difference detection circuit that detects the phase difference of received signals between beams, a high-pass filter, a dispersion value circuit that measures the dispersion of the signal processing circuit output value, and a dispersion value gate that determines whether the dispersion value exceeds a threshold value. An active sonar device comprising: a circuit; and a gate width determination circuit that determines whether an interval between dispersion value gates is longer than a certain time.