JPH11271445A - Apparatus and method for detecting distance to navigation object - Google Patents

Abstract

(57) [Problem] To provide a distance detecting device capable of detecting a distance to a traveling ship without transmitting a sound wave. SOLUTION: A sound wave receiver 11 for receiving a ship's running sound below the sea surface, and a point at which the ship comes closest to the sound wave receiver by differentiating once and twice the sound wave signal from the sound wave receiver. And a measurement position passing time point detecting unit 21 for detecting a time point when the vehicle passes a point in a 45-degree direction with respect to the closest position.
And a frequency analysis unit 22 for performing a frequency spectrum analysis of the sound wave signal, and a speed calculation unit 2 for inputting the passage times and the frequency spectrum analysis results to obtain a speed of the ship based on a frequency shift amount caused by the Doppler effect.
3, a differential value detecting unit 24 for detecting a value of the sound waveform differentiated twice at the closest position, and a distance for calculating the distance to the closest position by inputting the twice differential value and the speed of the ship. A configuration including a calculation unit 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for detecting a distance to a navigation object.

[0002]

2. Description of the Related Art Conventionally, there is an active type apparatus for detecting a distance to a ship traveling on the sea surface (or underwater).

In the active system, a detection device provided with a sound wave transmitter and a receiver for detecting a ship is arranged on the sea floor in a sea area where the ship travels, and is emitted (transmitted) from the sound wave transmitter. The receiver receives the sound waves returned by the reflected sound waves from the ship and detects the distance from the sound wave transmitter to the ship by multiplying the sound wave transmission / reception interval at this time by the sound speed in the sea. Met.

[0004]

However, according to the above-mentioned active system, there is a problem that it is necessary to transmit the sound wave by itself and to install the apparatus toward the sea surface in a predetermined area.

Accordingly, an object of the present invention is to provide a distance detecting device and a distance detecting method to a navigation object which can be easily installed without transmitting a sound wave by itself.

[0006]

In order to solve the above-mentioned problems, a distance detecting apparatus for a navigation object according to the present invention receives a traveling sound emitted from a navigation object traveling on the sea surface or under the sea below the sea surface. A sound wave receiver that performs the first and second differentiations on the sound wave signal from the sound wave receiver once and twice to pass through a point where the navigating object approaches the sound wave receiver closest to the sound wave receiver and to the closest position. A measurement position passing point detection unit that detects a second passing point passing through a point in the 45-degree direction,
A frequency analysis unit for inputting a sound wave signal from the sound wave receiver and performing a frequency spectrum analysis of the sound wave signal at predetermined time intervals; and first and second signals from the measurement position passing time point detection unit.
The passing time and the frequency spectrum analysis result from the frequency analysis unit are input, and the amount of frequency shift caused by the Doppler effect is obtained. After calculating the component, the velocity calculator detects the velocity of the navigating object in the traveling direction from the velocity component, the value at the first passage time point of the twice-differentiated sound wave waveform, and the velocity calculator. And a distance calculator for calculating the distance to the closest position by inputting the speed.

In the method for detecting a distance to a navigation object according to the present invention, a traveling sound emitted from a navigation object traveling on the sea surface or in the sea is received by a sound wave receiver provided below the sea surface,
The sound wave signal from the sound wave receiver is differentiated once and twice to obtain a first passage time when the navigating object passes through a point closest to the sound wave receiver and a 45 ° direction with respect to the closest position. At the second passing point passing through the point
A sound wave signal from the sound wave receiver is input and frequency spectrum analysis is performed at predetermined intervals, and a frequency shift amount caused by the Doppler effect is obtained from a frequency spectrum analysis result between the first passage time point and the second passage time point. After determining the velocity component of the navigating object in the direction of the sound wave receiver at the second passage time based on the amount of deviation, the velocity in the traveling direction of the navigating object is detected from the velocity component, and then the sound wave differentiated twice This is a method for detecting the distance from the sound wave receiver to the closest position based on the second derivative of the waveform at the first passage time and the speed calculated by the speed calculator.

According to each of the above-mentioned configurations, the traveling sound from the navigation object traveling on the sea surface or in the sea is received by the sound wave receiver, and the difference between the two frequencies at the different passing points is obtained. By applying the Doppler effect formula, we detect the speed of the navigating object,
Since the distance to the vessel is detected by using the velocity and the second derivative of the sound wave signal at the first passage, there is no need to output a signal for velocity detection, and the detection direction is not required. Is also omnidirectional.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a distance detecting device and a distance detecting method to a navigation object in an embodiment of the present invention will be described.
This will be described with reference to FIGS.

In the present embodiment, a case will be described in which the navigating object is a ship navigating on the sea surface (including the water surface). The distance detection method in the present embodiment is shown in FIG.
As shown in FIG. 1, at least a sound wave receiver (an example of an acoustic sensor, more specifically, a sound pressure sensor is used) 11 in the distance detecting device 1 is installed on the seabed in a predetermined sea area, and the ship 2 When navigating this sea area, it receives the sound wave of the running sound emitted from the ship 2, detects the speed of the navigating ship 2, and substitutes this speed into a predetermined calculation formula. It detects the distance to the ship at the closest position.

First, the configuration of the distance detection device and the principle of distance detection will be described. As shown in FIG. 2, the distance detecting device 1 includes a sound wave receiver 11 that is installed on the sea floor (or under the sea) and receives sound waves such as a running sound emitted from a ship 2 that sails on the sea surface. A sound wave signal (sound pressure signal) received by the sound wave receiver 11 is amplified by the amplifier 12 and then input, and a predetermined calculation is performed. The calculation processing detects the speed of the ship 2 and the distance to the ship 2 based on the speed. (A digital signal processor, a microcomputer, etc.) 13 and a transmission unit 1 for transmitting its detection speed, for example, a base station provided on land.
And 4.

The arithmetic processing unit 13 inputs the sound wave signal amplified by the amplifier 12 and detects a time point at which the ship has passed two predetermined measurement positions with respect to the sound wave receiver 11. A passing point detecting unit 21 and a frequency analyzing unit 22 that receives a sound wave signal from the amplifier 12 and performs a frequency spectrum analysis (FET analysis) of the sound wave signal.
A speed calculator 23 that inputs the passing time from the measuring position passing time detector 21 and the analysis result from the frequency analyzer 22 to calculate the speed of the ship 2 using the Doppler effect; Among the values obtained by differentiating the sound signal from the second time twice (this configuration will be described later),
A differential value detecting section 24 for detecting a second differential value at the first passage point; a predetermined calculation based on the speed obtained by the speed calculating section 23 and the second differential value obtained by the differential value detecting section 24; And a distance calculation unit 25 that calculates the distance to the ship 2.

The measuring position passing point detecting unit 21 includes a filter unit 31 such as a band-pass filter (or a low-pass filter) for extracting a necessary band from the amplified sound signal, and a predetermined signal from the sound signal extracted in this band. , A first differentiating circuit 33 for differentiating the extracted signal waveform, and a second differentiating circuit for further differentiating the signal waveform differentiated by the first differential circuit 33 34, a first passage time point detecting unit 35 for obtaining a zero point of the signal waveform by the first differentiation obtained by the first differentiating circuit unit 33, and a 2nd point obtained by the second differentiating circuit unit 34.
And a second passage time point detection unit 35 for obtaining a zero point of the signal waveform by the differential.

Here, a description will be given of the reason why the time point of passing through the vessel 2, that is, two positions to be measured is determined by the above-described first and second differentiations. As described above, it has been described that the speed of the ship 2 is detected by using the Doppler effect. In this case, the two frequencies obtained by measuring the sound wave signal of the ship 2 traveling at a predetermined speed at two different places are obtained. (Hereinafter referred to as shift amount), and then applying this shift amount to the equation of the Doppler effect to determine the true speed (in the traveling direction) of the ship 2. When applying the formula, it is necessary to know the fundamental frequency where no shift has occurred. For this reason, the fundamental frequency can be known by detecting the frequency at the time when the ship 2 passes through the position A (the closest position) A closest to the sound wave receiver 11.

That is, the fundamental frequency is equal to the sound wave receiver 1
The frequency at the time when the sound pressure level measured at 1 is the highest (strongest), and the position where the sound pressure level is the highest is
When the sound wave signal (sound pressure level signal) is differentiated once, the value becomes zero.

Next, for the reason of performing the second differentiation, the speed of the ship 2 obtained by the Doppler effect is a speed component of the sound wave receiver 11 out of the speed of the ship 2, and the speed component is calculated based on the speed component. It is necessary to find the true speed in the two traveling directions. Therefore, it is necessary to know the intersection angle θ between the direction of the velocity component and the traveling direction (see FIG. 4).

If the intersection angle θ is simply to be known from the sound wave signal received from the ship 2, the point of change of the sound pressure level, that is, the point where the intersection angle θ is 45 degrees can be easily obtained by differentiating twice. Because you can know.

Hereinafter, the above items will be specifically described. FIG.
As shown in the figure, the position of the sound wave receiver 11 of the speed detecting device 1 installed on the sea floor is set to the origin (0, 0, 0) in the three-dimensional coordinate system (X, Y, Z), and the vehicle travels. Assuming that the three-dimensional coordinates of the ship 2 are (x, y, z), the relative distance (linear distance) r between the ship 2 and the acoustic wave receiver 11 is given by the following (1).
It is represented by the formula. It should be noted that, by transforming equation (1), the ship 2
And the closest approach distance d between the sound wave receiver 11 and
It looks like an expression.

[0019]

(Equation 1)

The following equation (3) holds for the distance attenuation of the reception level of the sound wave emitted from the ship 2. RL = SL-TL (3) In the equation (3), RL: reception level at a sound wave receiver (dB) SL: transmission level of sound from a ship (dB) TL: propagation loss (dB) And TL = 20 logr.

In the above equation (3), x = vt [v indicates the speed of the ship 2, and t indicates the time required from the current position (detection position) B of the ship 2 to the closest position A to the underwater station 11. . ] Is substituted and transformed, the following equation (4) is obtained.

[0022]

(Equation 2)

The following equation (5) is obtained by differentiating the above equation (4) once, and the following equation (6) is obtained by differentiating it twice.

[0024]

(Equation 3)

Then, the value of the equation (6) differentiated twice is set to zero. That is, the molecule [(vt) ² −
The condition that the value of d ² ] becomes zero is when vt and d are equal, which means that the intersection angle θ between the current position B of the ship 2 and the closest position A of the ship 2 is 45 degrees. It is shown that.

Next, the frequency analysis unit 22 determines a band (for example, 1000 to 1) to be subjected to frequency spectrum analysis.
030 Hz) only.
And A / D for A / D converting a sound wave signal in this band.
A conversion unit 42 and an analysis unit 4 that performs frequency spectrum analysis (FET analysis) of the signal converted by the A / D conversion unit 42
3 and an analysis result recording unit 44 that records the analysis results at predetermined time intervals.

The analysis section 43 performs frequency spectrum analysis at predetermined time intervals, and each analysis result is recorded and held in the analysis result recording section 44. Then, the speed calculation unit 23 receives the analysis result from the analysis result recording unit 44 and the passage time, that is, the passage time obtained by the passage time detection units 35 and 36, and inputs the analysis result as shown in FIG. As described above, the two measurements are performed in accordance with the measurement positions (A, B) necessary for calculating the velocity, that is, based on the basic spectrum f ₀ indicating the fundamental frequency and the shift spectrum f _D when the intersection angle θ is 45 degrees. shift amount F _D spectrum is determined at the position.

[0028] Hereinafter, a procedure for obtaining the velocity v _r of the shift amount F wave receiver 11 direction of the boat 2 on the basis of _D.
The following equation (7) is obtained from the basic equation of the Doppler effect.

[0029] _{f D = {c / (c} -v r)} × f 0 ··· (7) where, c is represent sound. Here, the shift amount F _D is expressed by the following equation (8).

F _D = f _D −f ₀ (8) By substituting equation (7) into equation (8), the shift amount F
_D is represented by the following equation (9).

F _D = {c / (c−v _r )} × f ₀ −f ₀ = {v _r / (c−v _r )} × f ₀ (9) The above equation (9) is modified. Then, when v _r is obtained, the following (1)
Equation (0) is obtained.

V _r = F _D × c / (F _D + f ₀ ) = (F _D × c) / f _D (10) When v _r is obtained from the above equation (10), the following equation (1) is obtained.
The velocity v in the traveling direction of the boat 2 is obtained from the equation 1).

[0033] v = v _r / sinθ addition (11), in the differential value detecting section 24, a sound signal 2
Of the twice-differentiated waveform signal values, the twice-differentiated value at the first passing time point A (the maximum value when the value is positive, the minimum value when the value is negative) (-H) and the velocity calculation Based on the speed v obtained by the unit 23, a closest approach distance (shortest distance) d to the ship 3 is calculated.

Hereinafter, the calculation procedure will be described. In this calculation, the equation (3) indicating the received wave level is expressed by 2
The equation (6) obtained by performing the differential is used.

That is, when t = 0 is substituted into the equation (6) to find the position of the ship 2 at the closest approach position A (when t = 0), the following equation (12) is obtained.

[0036]

(Equation 4)

By the way, since the value on the left side of the above equation (12) when t = 0 is -H, the following equation (13) is established. When the equation (13) is transformed to obtain d, the following (1) is obtained.
Equation 4) is obtained.

[0038]

(Equation 5)

Next, a method of detecting the closest approach distance (shortest distance) to a ship by the above distance detecting device will be schematically described. First, the sound wave receiver 11 receives the sound wave of the traveling sound of the ship 2 sailing on the sea surface.

The received sound wave signal is amplified by the amplifier 12, and then input to the measuring position passing point detecting unit 21.
Here, once and twice differentiation is performed, and the time when the sound wave has passed the closest position A and the 45 degree position B from the sound wave receiver 11 is detected.

On the other hand, the sound wave signal amplified by the amplifier 12 is input to the frequency analysis unit 22 in parallel with the measurement position passage time point detection unit 21, where the frequency spectrum at every predetermined time is obtained.

Then, the passing time of the closest approach position A and the 45 ° position B obtained by the first and second passing time detecting units 35 and 36 in the measuring position passing time detecting unit 21 and the analysis by the frequency analyzing unit 22 are performed. The result is input to the speed calculator 23.

Here, as shown in FIG. 3, each position A,
After the shift amount F _D of the frequency from the graph showing the corresponding frequency spectrum to the passage time at B is determined, on the basis of the (10) equation, the velocity component v _r in the wave receiver 11 direction is determined, Further, the true velocity v of the boat 2 in the traveling direction is obtained from the equation (11).

Next, the value obtained by the second differentiating circuit section 34 is input to the differential value detecting section 24, where the minimum value (-H) which is the second differential value at the first passing time point A is obtained. Can be

Then, the speed v and the minimum value (-H) of the ship 2 are input to the distance calculator 25, and the distance to the closest position A of the ship 2, that is, the shortest distance d is calculated. The obtained shortest distance d is transmitted to a land-based base station via the transmission unit 14, and displayed on a monitor, for example.

As described above, the traveling sound from the ship traveling on the sea surface is received by the sound wave receiver, the shift amount of both frequencies at different passing points is obtained, and the Doppler effect equation is applied to the shift amount. Then, while detecting the speed of the ship, and using the second derivative of the sound wave signal to detect the shortest distance to the ship, as in the prior art, the detection signal from the distance detection device side. It is not necessary to output, and the detection direction is omnidirectional, so compared to those using an azimuth detector,
The installation can be performed very easily.

In the above embodiment, the case where the distance to a ship navigating on the sea surface is detected, but the present invention is also applied to the detection of the distance to an object navigating in the sea (including underwater) such as a submarine. can do.

[0048]

As described above, according to the distance detecting apparatus and the distance detecting method of the present invention, the traveling sound from the navigating object navigating on the sea surface or under the sea is received by the sound wave receiver, and at the same time, the traveling sound at the different passing points Find the frequency shift amount,
Then, the speed of the navigating object is detected by applying the formula of the Doppler effect to the deviation amount, and the distance to the ship is detected by using the speed and the second derivative of the sound wave signal at the first passage. So, as before,
It is not necessary to output a detection signal from the distance detection device side, and the detection direction is omnidirectional,
The installation can be performed very easily as compared with the one using an azimuth detector.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an arrangement state of a ship and a sound wave receiver according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of a distance detection device according to the embodiment.

FIG. 3 is a diagram showing a frequency spectrum analysis result in a frequency analysis unit of the distance detection device.

FIG. 4 is a diagram illustrating a procedure for obtaining a speed in a speed calculation unit of the distance detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distance detection device 2 Ship 11 Sound wave receiver 13 Arithmetic processing part 21 Detecting point at the time of passage of measurement position 22 Frequency analysis part 23 Speed calculation part 24 Differentiation maximum value detection part 25 Distance calculation part 33 First differentiation circuit part 34 Second differentiation circuit Unit 35 first passage time detection unit 36 second passage time detection unit 43 analysis unit 44 analysis result recording unit

Claims (2)

[Claims] 1. A sound wave receiver for receiving a traveling sound emitted from a navigation object traveling on the sea surface or under the sea below the sea surface, and performing a first and second differentiation on a sound wave signal from the sound wave receiver. The first passage time when the navigation object passes through the point closest to the acoustic wave receiver and 45 degrees with respect to this closest position
A measurement position passage time point detection unit that detects a second passage time point passing through a point in the degree direction, a frequency analysis unit that inputs a sound wave signal from the sound wave receiver and performs a frequency spectrum analysis of the sound wave signal at predetermined time intervals. The first and second passage times from the measurement position passage time detection unit and the frequency spectrum analysis result from the frequency analysis unit are input to determine the frequency shift amount caused by the Doppler effect, and A velocity calculator for detecting a velocity component of the navigating object in the direction of the sound wave receiver at the time of the second passage, and detecting a velocity of the navigating object in the traveling direction from the velocity component; And a distance calculator for calculating the distance to the closest position by inputting the second derivative at the time of the first passage and the speed calculated by the speed calculator. Distance detecting device to sailing object to symptoms. 2. A traveling sound emitted from a navigation object traveling on the sea surface or in the sea is received by a sound wave receiver provided below the sea surface, and a sound wave signal from the sound wave receiver is differentiated once and twice. Detecting a first passage time point when the navigation object passes through a point closest to the sound wave receiver and a second passage time point passing through a point in a direction of 45 degrees with respect to the closest position. The frequency spectrum analysis is performed at a predetermined interval by inputting the sound wave signal from the input unit, and the frequency shift amount caused by the Doppler effect is obtained from the frequency spectrum analysis result between the first pass time point and the second pass time point. After obtaining the velocity component of the navigating object in the direction of the sound wave receiver at the time of the second passage, the velocity in the traveling direction of the navigating object is detected from the velocity component, and then the first of the twice differentiated sound wave waveform is obtained. Through Based on the rate determined by the second derivative values and the speed calculation unit at the time, the distance detection method to navigation object and detects the distance to the closest position from the wave receiver.