JPH0850172A - Sound wave direction finding device - Google Patents

Abstract

PURPOSE:To quickly and precisely detect the existing directions of a plurality of navigating ships by a foghorn on the sea with poor visibility by providing a plurality of echo sounder receivers having a receiver directivity wider than the monitor target sector angle of the foghorn sound wave. CONSTITUTION:A level comparing circuit 3 compares the received signal from echo sounder receivers 1, 2 having receiving characteristic wider than the monitor target sector angle of foghorn sound wave. A direction collimating circuit 4 collimates the compared value with the comparison standard value of directivity characteristic of the receivers 1, 2 to a predetermined incident direction to roughly determine a sound source direction. A wavelength number arithmetic circuit 5 converts the sound wave propagation route difference from the sound source to the receivers 1, 2 into wavelength number on the basis of the sound wave frequency detected by a frequency detecting circuit 6 and the rough sound source direction. A phase difference detecting circuit 7 detects the phase difference between the received sound waves of the receivers 1, 2, and 2 direction arithmetic circuit 8 precisely calculates the sound source direction by use of the phase difference, the sound wave frequency, and the wavelength number of route difference. The calculated sound source direction is displayed on a direction indicator 9.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention relates to a system for ensuring navigation safety by detecting the azimuths of a plurality of navigating vessels more quickly and accurately by a fog whistle on the sea where a vessel in a fog voyage has poor visibility.

[0002]

2. Description of the Related Art A radar is generally used to detect the presence of another ship during voyage in fog, but if the measurement target ship is a wooden ship, it is impossible to measure it. Its existence is clarified to avoid the danger of collision. However, although the presence of other vessels can be clearly confirmed by the fog whistle, the azimuth of the sound was detected only by the sense of hearing of the operator, and its accuracy was rather vague. Further, when the azimuth is measured using the sound wave, the pulse sound wave is used in the positional relationship shown in FIG. 4, and the propagation path difference is obtained from the arrangement interval d of the two wave receivers and the arrival time difference of the pulse sound wave, and It is also possible to calculate the sound source direction θ. Sound source azimuth angle θ = arcSIN (c · Δt / d) where: d: receiver arrangement interval c: sound velocity Δt; arrival time difference of sound waves However, in this method, when the sound waves are continuous waves, two receivers are used. The arrival time difference of sound waves cannot be measured, and the sound source direction cannot be calculated. There is also a method of calculating the sound wave propagation path difference by the phase difference between the received signals. In this case, it is determined whether the sound wave propagation path difference is within one wavelength of the sound wave frequency and whether the target azimuth is on the right or left of the monitoring center azimuth. Must be known.

[0003]

[Problem to be Solved by the Invention] When a fog whistle of another ship is heard in a ship or the like while navigating in a fog, the system immediately measures the direction of the fog whistle and establishes a navigation safety system.

[0004]

[Means for Solving the Problems] Regarding a system for ensuring the safety of navigation by confirming the presence direction of another ship by the fog whistle of another ship during fog navigation, a receiving direction wider than the sector angle of the fog whistle sound wave is monitored. With the two wave receivers held, the wave receiving directivity center of the wave receiver is arranged within the full width at half maximum of the effective wave receiving direction, with respect to the center of the monitored sector angle. By comparing the comparison value of the received signal level of the wave receiver and the comparison reference value of the wave receiving directional characteristic with respect to the sound wave incident azimuth of each wave receiver, the incident azimuth angle of the sound wave is roughly calculated. Accurate direction of arrival of sound waves is calculated by measuring the phase difference and frequency of the received signal of the receiver, thereby measuring the direction of existence of other vessels and improving navigation safety.

[0005]

1 is a block diagram showing an embodiment of the present invention. In the present embodiment, the fog whistle sound monitoring sector angle is set to −60 °.
It is set to + 60 °. In FIG. 1, 1 and 2 are wave receivers, 3 is a level comparison circuit for comparing the received signal levels from the wave receivers 1 and 2, and 4 is a comparison value obtained by the level comparison circuit 3 and is previously obtained. An azimuth matching circuit for roughly determining the sound source azimuth by comparing the received directional characteristics of both receivers 1 and 2 with respect to the sound wave incident azimuth, 6 is a sound wave frequency from the received signal of the receiver 1. Is a frequency detection circuit for detecting the difference between the sound wave propagation paths between the wave receivers 1 and 2 from the sound source based on the sound wave frequency detected by the frequency detection circuit 6 and the rough sound source direction obtained by the direction matching circuit 4. The number-of-wavelengths arithmetic circuit for converting the distance into the number of wavelengths of sound waves, 7 is a phase detection circuit for detecting the phase difference between the two received sound waves by the reception signals of the wave receivers 1 and 2, and 8 is the phase difference detection circuit 7. The detected phase difference and the frequency detection circuit 6 detect A direction calculation circuit for accurately calculating the sound source direction using the sound wave frequency and the number of wavelengths of the path difference calculated by the wavelength number calculation circuit 5, and 9 is a direction indicator for displaying the sound source direction calculated by the direction calculation circuit 8. Is. In addition, the wave receivers 1 and 2 in FIG.
As shown in Fig. 3, the directivity centers of both receivers are arranged at an opening distance d of ± 10 ° with respect to the center direction of the fog whistle sound monitoring sector. As shown in FIG. 3, both receivers arranged as shown in FIG. 2 have different received signal levels for the same sound source depending on the direction of the sound source.

The operation of the sonic azimuth measuring device configured as described above will be described below. First, the reception directional characteristic D using the sound source direction θ of each of the wave receivers 1 and 2 as a parameter.
(Θ) is expressed by the following equation. D (θ) = A · COS (θ) θ: −90 ° to
+ 90 ° A: Constant Since the directivity center of both receivers is placed ± 10 ° apart from the center direction of the fog whistle sound monitoring sector, both receivers when the fog whistle sound generation direction is θ The ratio of the levels of the received signals in is obtained in advance as D (θ-10 °) / D (θ + 10 °) as shown in Table 1. Although Table 1 shows the ratio of the level of the received signal to the azimuth every 10 °, the azimuth can be subdivided as necessary.

[Table 1] Therefore, the azimuth collation circuit 4 can roughly determine the fog whistle sound azimuth by collating the comparison value of the levels of the reception signals of the both receivers detected by the level comparison circuit 3 with the data in Table 1. The coarse fog whistle sound azimuth calculated by the azimuth matching circuit 4 is ψ.

Further, in the arrangement relationship shown in FIG. 3, when the sound source azimuth angle is θ, the path difference c of the sound wave propagation between the two receivers c
-At is given by the following equation. c · Δt = d · SIN (θ) Using the relation of this equation, the sound source frequency is set to f, and ψ obtained by the above-mentioned azimuth matching circuit 4 is substituted into θ, and the phase difference between the received signals of the two wave receivers is obtained. When Φ is obtained, Φ = (2πf) Δt = (2πf) d · SIN (ψ) / c where Φ = 2πn + φ and n = ((2πf) d · SIN (ψ) / c) / 2π When calculated, n is the number of wavelengths of the sound wave included in the path difference, and φ
Is the phase difference within one wavelength (2π) of the received signals of the two wave receivers. Based on this equation, using the rough azimuth angle ψ that is the output of the azimuth matching circuit 4 and the sound source frequency f that is the output of the frequency detection circuit 6, the wavelength number calculation circuit 5 determines the difference between the sound wave propagation paths of the wave receivers 1 and 2. The wavelength number n in is calculated.

Here, the azimuth angle ψ in the above equation is a rough measurement value, and Φ includes many errors, but these errors are determined by the accuracy of the directivity of the receiver unit, and are generally 1
It can be set within the wavelength range and within the range of the phase difference φ. Further, the phase difference φ can be accurately measured as the phase difference between the two received signals, and is measured by the phase difference detection circuit 7.

Next, by using the phase difference φ measured by the phase difference detecting circuit 7, the number of wavelengths n in the path difference calculated by the wavelength number calculating circuit 5 and the sound source frequency f measured by the frequency detecting circuit 6, , The sound source azimuth angle θ can be accurately calculated from the positional relationship of FIG. Direction calculation circuit 8
Calculates the sound source azimuth angle θ. θ = arcSIN (c · Δt / d) = arcSIN (c · (n + (φ / 2π)) / f / d) The azimuth indicator 9 is the sound source azimuth θ output from the azimuth calculation circuit 8.
Based on, the fog whistle sound direction is displayed on the display.

In this embodiment, the comparison value of the reception signals of the two wave receivers is collated with the data of the comparison reference value of the wave reception directional characteristic with respect to the sound wave incident direction of the two wave receivers prepared in advance. The sound source azimuth was obtained, and the comparison reference value of this receiving directional characteristic is
It is also possible to compare with the received signal comparison value obtained by direct calculation from the directional characteristic function of the receiver.

[0011]

[Effects of the Invention] Since the direction of the fog whistle generated by another ship in the same sea area can be detected instantaneously (within 1 second), a plurality of fog whistle sounds alternately emitted by a number of surrounding ships are arranged on the circumference. All the directions can be calculated by hearing with the combination of the receivers. For all ships that have a simple sound source with a single frequency, such as a fog whistle, it is possible to determine the bearing by transmitting sound waves for a short time, so small boats can also be detected. The azimuth detection accuracy is high, and it is possible to determine to some extent whether or not the approach target has a risk of collision based on the azimuth changes caused by the motions of the own ship and the target ship.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an arrangement of two wave receivers in the embodiment.

FIG. 3 is a diagram showing a sound source direction and received signal levels of two wave receivers.

FIG. 4 is a diagram showing a relationship between a sound source direction and a path difference between two wave receivers.

[Explanation of symbols]

 1, 2 Wave receiver 3 Level comparison circuit 4 Direction matching circuit 5 Wavelength number calculation circuit 6 Frequency detection circuit 7 Phase difference detection circuit 8 Direction calculation circuit 9 Direction indicator

Claims (1)

[Claims] 1. A system for confirming the presence of another ship by a fog whistle to ensure navigation safety, which has a reception directivity wider than a sector angle of a fog whistle to be monitored, and receives each wave with respect to the center of the sector angle of the fog. Two wave receivers in which the center of the wave receiving directivity of the receiver is arranged within the half width of the effective wave receiving direction, and the received signals are input from the two receivers. By comparing the level comparison value and the comparison reference value of the reception directional characteristics with respect to the sound wave incident directions of the two receivers,
A true value is obtained by a calculation unit that roughly estimates the sound wave incident direction and the phase difference and frequency of the received sound waves of the two receivers, and the measured phase difference and frequency and the sound wave incident direction that is calculated by the rough calculation unit. A sound wave direction measurement apparatus comprising: a calculation unit that calculates a sound wave direction.