JPH11271446A - Apparatus and method for detection of speed of cruising object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speed detecting apparatus by which the speed of a cruising ship can be detected without transmitting sound waves. SOLUTION: A speed detecting apparatus is constituted of a sound wave receiver 11 which receives the sound of a ship under the surface of the sea, of a measuring position passage time detection part 21 wherein a sound wave signal from the sound wave receiver 11 is differentiated and processed, a first passage point of time in which the ship passes a closest position with reference to the sound wave receiver 11 is detected and a second passage point of time in which the ship passes a point in a direction at 45 deg. to the closest position is detected, of a frequency analysis part 22 to which the sound wave signal from the sound wave receiver 11 is input and which analyzes the frequency spectrum of the sound wave signal in every prescribed time and of a speed calculation part 23 to which the first passage point of time and the second passage point of time from the measuring position passage time detection part 21 and the analyzed result of the frequency spectrum from the frequency analysis part 22 are input, which finds the shift amount of a frequency generated due to the Doppler effect, in which the speed component in the direction of the sound wave receiver 11 of the ship in the second passage point of time is found on the basis of the shift amount and in which the speed in the advance direction of the ship is detected on the basis of the speed component.

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 the speed of a traveling object.

[0002]

2. Description of the Related Art Conventionally, there are an active system and a passive system for detecting the speed of a ship traveling on the sea surface (or the sea).

[0003] In the active type, a detecting 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 a sound wave emitted from the sound wave transmitter is provided. Received by the receiver the sound wave reflected back to the ship, using the Doppler effect,
It detects the speed of the ship.

[0004] On the other hand, in the passive type, a sound wave receiving device is arranged at two different places on the sea floor, and a traveling sound emitted from the ship is detected at two places with a time difference, so that the ship can be detected from the time difference. Is to determine the speed.

[0005]

According to the above-mentioned active system, there is a problem that it is necessary to transmit a sound wave by itself and to be installed toward the sea surface in a predetermined area. Each sound wave receiving device requires three azimuth angle detectors, so that a total of six azimuth angle detectors are required, and the azimuth angle detectors are also set to face the sea surface in a predetermined sea area. Had to be done and was very troublesome.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a speed detecting apparatus and a speed detecting method for a navigating object which can be easily installed without transmitting a sound wave by itself.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a navigation object speed detecting apparatus 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, a first passage time point at which a sounding signal from the sound wave receiver passes through a point at which the navigating object approaches the sound wave receiver by differentiating the sound wave receiver, and a 45 ° direction with respect to the closest approach position A measurement position passage point detection unit that detects a second passage point passing through the point of interest, 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 every predetermined time, The first and second passage times from the measurement position passage time detection unit and the frequency spectrum analysis results from the frequency analysis unit are input to determine the frequency shift amount caused by the Doppler effect. A speed calculator for determining a speed component of the navigating object in the direction of the sound wave receiver at the time of the second passage from the deviation amount, and detecting a speed of the navigating object in the traveling direction from the speed component. is there.

Further, according to the method for detecting the speed of a navigating object of the present invention, a traveling sound emitted from a navigating object navigating on the sea surface or under the sea is received by a sound wave receiver provided below the sea surface, A differential processing is performed on the sound wave signal, and a first passage time when the navigation object passes through a point closest to the sound wave receiver and a second passage time when the navigation object passes through a point in a 45-degree direction with respect to the closest position. Detecting and inputting a sound wave signal from the sound wave receiver and performing frequency spectrum analysis at predetermined intervals, and calculating a frequency shift amount caused by the Doppler effect from the frequency spectrum analysis results at the first and second passage times. After calculating the velocity component of the navigating object in the direction of the sound wave receiver at the second passage time based on the deviation amount, the speed in the traveling direction of the navigating object is detected from the velocity component. It is that way.

According to each of the above-described 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. Since the speed of the navigating object is detected by applying the Doppler effect formula, it is not necessary to output a signal for speed detection, and the detection direction is omnidirectional.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a speed detecting apparatus and a speed detecting method for a navigating object according to an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

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 speed 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 of the speed detecting device 1 is installed on the seabed in a predetermined sea area, and the ship 2 Receives the sound of the traveling sound emitted from the vessel 2 when traveling in this sea area, and automatically detects the speed of the vessel 2 traveling.

First, the configuration of the speed detection device and the principle of speed detection will be described. As shown in FIG. 2, the speed detection device 1 includes a sound wave receiver 11 that is installed on the sea floor (or underwater) and receives sound waves such as running sounds 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 an amplifier 12 and then input, and a predetermined calculation is performed to detect a speed of the ship 2 (a digital signal processor, a microcomputer or the like). 13), and a transmitting unit 14 for transmitting the detected speed, such as a base station provided on land.

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 calculation unit 23 that inputs the passing time from the measurement position passing time detection unit 21 and the analysis result from the frequency analysis unit 22 and calculates the speed of the ship 2 from the Doppler effect.
It is composed of

The measuring position passing point detecting section 21 includes a filter section 31 such as a band-pass filter (or a low-pass filter) for extracting a required band from the amplified sound signal, and a predetermined section 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 passing time point of the ship 2, that is, two measurement target positions is determined by the 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 that the differentiation is performed twice, the speed of the ship 2 obtained by the Doppler effect is a speed component of the sound wave receiver 11 among the speeds 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.

[0020]

(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.

[0023]

(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.

[0025]

(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 frequency spectrum analysis target band (for example, 1000 to 1).
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.

[0029] 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.

[0030] _{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).

[0034] _{v = v r / sinθ ··· (} 11) Next, by the speed detecting device, illustrating a method of detecting the speed of the ship schematically. First, the sound wave receiver 11 receives the sound wave of the traveling sound of the ship 2 sailing on the sea surface.

After the received sound wave signal is amplified by the amplifier 12, it is inputted to the measuring position passing point detecting section 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 of 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).

It should be noted that the obtained speed v is
Is transmitted to a land-based base station via a PC and displayed on a monitor, for example. In this way, while receiving the running sound from the ship sailing on the sea surface with the sound wave receiver, calculating the shift amount of both frequencies at different passing points, and applying the Doppler effect equation to this shift amount, Since the speed of the ship is detected, there is no need to output a detection signal from the speed detection device as in the past, and the azimuth detector is used because the detection direction is omnidirectional. The installation can be performed extremely easily as compared with the case of performing the installation.

In the above-described embodiment, only one frequency analysis unit 22 is provided. However, for example, as shown in FIG. 5, two frequency analysis units 22 and 22 'may be provided in parallel. In this case, the frequency bands to be subjected to the frequency spectrum analysis are made different from each other, and speed calculation units 23 and 23 'are provided in accordance with the respective frequency analysis units 22 and 22'. The speeds obtained at 23 and 23 'are input to the speed calculation result collation unit 51 and collation is performed, thereby improving the speed detection accuracy.

In the above embodiment, the case where the speed of a ship navigating on the sea surface is detected has been described. However, the present invention is also applied to the detection of the speed of an object navigating in the sea (including underwater) such as a submarine. be able to.

[0042]

As described above, according to the speed detecting apparatus and the speed detecting method of the present invention, the traveling sound from the navigating object traveling on the sea surface or under the sea is received by the sound wave receiver, and the traveling sound at the different passing points is received. Find the frequency shift amount,
Since the speed of the navigating object is detected by applying the Doppler effect formula to this amount of deviation, it is not necessary to output a detection signal from the speed detection device side, as in the related art, and the detection direction is not required. Is omni-directional, so that its installation can be performed extremely easily as compared with those using an azimuth angle 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 speed detection device according to the embodiment.

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

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

FIG. 5 is a block diagram illustrating a schematic configuration of a modified example of the speed detection device according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Speed detection apparatus 2 Ship 11 Sound wave receiver 13 Arithmetic processing unit 21 Measurement point passage time point detection unit 22 Frequency analysis unit 23 Speed calculation unit 33 First differentiation circuit unit 34 Second differentiation circuit unit 35 First passage time detection unit 36 First 2 passage point 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 in the sea below the sea surface, and performing a differentiation process on a sound wave signal from the sound wave receiver to the sound wave receiver. The first that passes through the point where the navigating object approaches
A measuring position passing point detecting unit for detecting a passing point and a second passing point passing through a point in a direction of 45 degrees with respect to the closest position, and a sound wave signal input from the sound wave receiver for receiving sound waves at predetermined time intervals A frequency analysis unit that performs a frequency spectrum analysis of the signal; and a first and a second passage time points from the measurement position passage time point detection unit and a frequency spectrum analysis result from the frequency analysis unit. A speed calculator for calculating a shift amount, determining a speed component of the navigation object in the direction of the sound wave receiver at the second passage time from the shift amount, and detecting a speed in the traveling direction of the navigation object from the speed component. And a speed detecting device for a navigating object. 2. A traveling sound emitted from a navigation object traveling on the sea surface or under 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 subjected to differentiation processing to receive a sound wave. The first passage point when the navigating object passes through the closest point to the vessel and 4
A second passing time point passing through a point in the 5-degree direction is detected, a sound wave signal from the sound wave receiver is input, and a frequency spectrum analysis is performed at predetermined intervals, and the frequency between the first passing time point and the second passing time point is determined. The amount of frequency shift caused by the Doppler effect is obtained from the spectrum analysis result, and based on the amount of shift, the velocity component of the navigating object in the direction of the sound wave receiver at the second passage is obtained. A method for detecting a speed of a navigating object, comprising detecting a speed at a ship.