JPH0141948B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a ship speed measurement device that emits ultrasonic waves into the sea, receives reflected waves from the seabed, and detects ship speed using the Doppler effect. The present invention relates to a method and apparatus for tracking reflected waves in response to changes in the seabed by setting a tracking gate for receiving the reflected waves whose return time changes depending on the slope of the seabed.

[Prior Art] A speed measurement device for a ship is configured to emit an ultrasonic beam diagonally forward and backward from the bottom of the ship, receive reflected echoes from the seabed, and determine the speed of the ship from the Doppler frequency.

Conventionally, this type of ship speed measuring device cannot accurately determine the ship's speed when reflected waves from sources other than the seabed, such as from water bodies or schools of fish between the bottom of the ship and the seabed, are detected. In the circuit, a gate is provided to set the reception timing,
The structure was such that only the reflected waves received within this gate were detected and their Doppler frequency was determined. In this case, the width and position of the gate need to be set according to the depth of the seabed.

Therefore, conventionally, in addition to measuring the depth of the ocean floor,
By predicting changes in the depth of the ocean floor to a certain extent and setting gates with symmetrical widths before and after the predicted depth, it was possible to track changes in the ocean floor.

[Problems to be Solved by the Invention] However, although this conventional method of setting gates based on the seabed tracking method can cope with cases where the seabed topography changes are relatively gentle, it cannot cope with cases where the seabed has a steeply sloped surface. However, there was a problem that the return time of the reflected waves changed significantly, making it impossible to cope with the problem.

This problem is also related to ship speed, and as the ship speed increases, the change in the return time of the reflected waves also increases. Therefore, in the conventional submarine tracking method,
There was a problem that if the ship was moving fast, it would not be possible to track the ship.

The present invention has been made to solve the above problems, and the width of the tracking gate is selected according to the inclination of the seabed and the speed of the ship, so that it can respond to sudden changes in the topography of the seabed and changes in ship speed, and can reliably It is an object of the present invention to provide a seabed tracking method and device for a ship speed measuring device capable of tracking the seabed.

[Means for solving the problems] The first invention of the present application for solving the above problems is as follows:
A ship speed measurement device that emits ultrasonic waves into the sea, receives reflected waves from the seabed, and detects the ship's speed using the Doppler effect, and a tracking system that receives the reflected waves whose return time varies depending on the slope of the seabed. Set the gate and
This is a method of tracking reflected waves in response to changes in the ocean floor.The time from transmission to reception is counted, the measured depth is detected, and the depth detected above is used as a reference point. Set the tracking gate width so that it is shorter and longer toward the deeper end, and in the opposite direction to the direction of travel, longer toward the shallower end and shorter toward the deeper end, and the tracking gate width is set as a function of the speed of the ship. The gate width is set to expand and contract depending on the speed.

In addition, the second invention of the present application, which is a device for realizing the seabed tracking method of the ship speed measuring device, emits ultrasonic waves into the sea, receives reflected waves from the seabed, and detects the ship speed by the Doppler effect. A tracking gate is installed on the ship's speed measurement device to receive the reflected waves whose return time changes depending on the slope of the seabed.
It is a device that tracks reflected waves in response to changes in the ocean floor, and includes a bathymetric device that measures the time from transmission to reception to detect the measured depth; Set the tracking gate width as a function of the ship speed above so that it is shorter in the shallow direction and longer in the deeper direction, and in the opposite direction to the direction of travel, it becomes longer in the shallow direction and shorter in the deeper direction, and after the start of the next transmission The tracking gate setting means outputs the tracking gate start timing and the tracking gate end timing.

[Operation] The operation of the first and second inventions of the present application configured as described above will be explained with reference to FIGS. 1 to 4. In addition, Fig. 1 is an explanatory diagram showing the influence of the movement of the ship and the inclination of the seabed on the propagation path of ultrasonic waves in front of the ship, and Fig. 2 is a waveform diagram showing the relationship between the time required from transmission to reception and the tracking gate. FIG. 3 is a graph showing the relationship between the inclination angle of the seabed and T _R /T _L , and FIG. 4 is an explanatory diagram showing the influence of the movement of the ship and the inclination of the seabed on the propagation path of ultrasonic waves behind the ship.

In FIG. 1, it is assumed that the ship is moving on the sea surface from _S1 to _S2 . First, at position S ₁ , when an ultrasonic wave is emitted from a transducer (not shown) in front of the ship (in the traveling direction) at an angle of depression θ, and if the distance to the sea floor A is R ₁ , then the seafloor echo will be The time T until it is received is T=
2R ₁ /ρ.

Next, suppose that when the ship advances and reaches S ₂ , the topography of the ocean floor changes as shown by C or C' depending on the inclination angle φ. In this case, the distance from S ₂
R ₂ becomes R ₁ − or R ₁ +′. Here, the time required from transmission to reception as shown in Figure 2.
Based on T ₁ , the front (shallow side) side of the gate width T _L
, T _L =2/c, and the rear (deeper) side T _R is,
If T _R =2'/c, the ratio of both T _R /T _L is
It is given by the following formula.

Now, if θ=60°, the above T _R /T _L becomes as follows.

T _R /T _L = sin (60 + φ) / sin (60 − φ) In Figure 3, at angles other than 0°, this ratio is
(T _R /T _L )>1. Therefore, the measurement depth is detected by counting the time from transmission to reception.
Based on the depth detected above, in the direction of travel:
By setting the gate width asymmetrically so that it is shorter on the shallow side and longer on the deeper side, it is possible to cope with the slope of the seabed.

On the other hand, in the above case, when ultrasonic waves are radiated to the rear of the ship (in the direction opposite to the direction of travel) at an angle of depression θ, the result will be as shown in FIG. 4. As is clear from a geometrical comparison of Figures 1 and 4, the above
The relationship between T _R and T _L is T _R < T _L. Therefore, in the direction opposite to the direction of travel, by setting the tracking gate width asymmetrically so that it is longer on the shallower side and shorter on the deeper side, it is possible to cope with the inclination of the seabed.

[Example] An example of the present invention will be described with reference to the drawings.

<Configuration of Embodiment> FIG. 5 shows a block diagram of an example of a tracking device for implementing the seabed tracking method using the ship speed measuring device of the present invention. In addition, in order to simplify the drawing and explanation, FIG. 5 shows only the circuit parts necessary for emitting ultrasonic waves forward, but normally,
There are both front and rear circuits.

In FIG. 5, the tracking device of this embodiment is attached to a ship speed measuring device 10 comprising a transducer 11, a transceiver switching section 12, a transmitting section 13, a receiving section 14 and a frequency detecting section 15, and a flip-flop 21 and a counter 22;
The tracking gate setting means 30 includes an arithmetic circuit 31, counters 32, 33, and an AND gate circuit 34.

The transmitter 13 includes an oscillator (not shown),
Intermittently outputs a high frequency signal from the oscillator,
A pulsed excitation current is sent to the transducer 11 via the transmission/reception switching section 12. Further, the transmitter 13 outputs a transmit trigger for setting the timing of intermittent output of the high frequency signal to the flip-flop circuit 21 and the counter 32.

The transmission/reception switching unit 12 performs switching so that the excitation current from the transmitting unit 12 is sent to the transducer 11, while the received signal from the transducer 11 is input to the receiving unit 14.

The receiving section 14 amplifies the received signal to a necessary level, sends the submarine signal frequency to the frequency detecting section 15 , detects the signal, extracts its envelope, and sends it to the AND gate circuit 34 .

The frequency detection unit 15 receives the submarine envelope signal that has passed through the AND gate circuit 34, detects the Doppler shift from the submarine signal frequency, and calculates the ship speed V.

The arithmetic circuit 31 includes, for example, a microprocessor that performs arithmetic operations, an operating program for the microprocessor, a ROM (read-on memory) that stores coefficients K _F and K _B necessary for calculation, and a storage area necessary for arithmetic operations. It is configured with RAM (random access memory). This arithmetic circuit 31
sets a tracking gate start signal T ₁ −T _F and end signal T _F +T _B from the above-mentioned ship speed V and depth T ₁ .
In addition, in this example, the case where ultrasonic waves are emitted in the direction of movement of a ship is taken as an example, so the coefficients K _F and K _B
are set so that their magnitude relationship is K _F <K _B.

The counters 32 and 33 are both preset counters, and the former receives the tracking gate start signal.
T ₁ -T _F is preset, and the latter is preset with the end signal T _F +T _B , and both form a tracking gate signal.

The AND gate circuit 34 has a configuration in which the opening and closing of the gate is controlled by the tracking gate signal which is inverted and input, and receives the submarine signal envelope from the receiving section 13 when the tracking gate signal is at a low level.

<Operation of the embodiment> The tracking device of the embodiment configured as described above has the following features:
It works as follows. This effect will be explained with reference to FIGS. 5 and 6.

First, in the boat speed device 10, an excitation current is transmitted from the transmitting section 13 to the transducer 11 via the transmitting/receiving switching section 12.
sent to. At this time, a transmission trigger is sent to the flip-flop circuit 21 and the counter 32. In response to this, the flip-flop circuit 21 enters the set state, outputs the sounding gate signal _TG , and starts counting of the counter 22. Counter 22 begins counting the clock signals. Similarly, counter 32 starts counting clock signals upon receiving the transmission trigger.

The ultrasonic waves emitted into the sea from the transducer 11 are
A part of it is reflected on the seabed and received by the transducer 11. The received signal is sent to the receiving section 14 via the transmission/reception switching section 12. The receiving section 14 amplifies the received signal, sends the submarine signal frequency to the frequency detection section 15 , detects it, and sends the submarine signal envelope to the AND gate circuit 34 .

When the submarine signal envelope is input to the AND gate circuit 34 while the tracking gate signal is at a low level, this signal is recognized as a submarine signal and is output to the frequency detection section 15 and the flip-flop circuit 21. In response to this, the frequency detection unit 15 detects the Doppler shift and
Calculate the ship speed V. Furthermore, the flip-flop circuit 21 is reset.

By resetting the flip-flop circuit 21,
The sounding gate signal T _G is terminated, and counting by the counter 22 is stopped. The counted value of the counter 22 at this time is the depth _T1 since the clock signal corresponding to the unit distance is counted.

The arithmetic circuit 31 calculates the front side T _F and the rear side T _B of the tracking gate gate width from the ship speed V and the pre-stored coefficients K _F and K _B using the following equations.

T _F = K _F V T _B = K _B V After this, the arithmetic circuit 31 calculates the tracking gate start signal T ₁ −T _F from the depth T ₁ output from the counter 22 and the above T _F and T _B. , the end signal T _F +T _B is calculated. The start signal T ₁ -T _F and the end signal T _F +T _B are used in the next transmission cycle, and before the next transmission, the start signal T ₁ -T _F is preset in the counter 32 and the end signal T F +T B is used in the next transmission cycle. The signal T _F +T _B is preset in the counter 33.

In this state, when the next transmission trigger is output from the transmitter 13, the flip-flop circuit 21 is set and the sounding gate is started. Also,
The counter 32 is started and counts down from the preset value of the start signal T ₁ -T _F by the clock signal. Then, when the count value of the counter 32 becomes 0, the counter 33 is activated by its output and counts down from the preset value of the end signal T _F +T _B by the clock signal.
Then, when the count value of the counter 33 becomes 0,
The counting ends, and the low level region of the counters 32 and 33 during the counting period becomes the tracking gate signal.

This tracking gate signal is inverted and input to the AND gate circuit 34. With this, the current tracking gate is set.

In this example, the case where ultrasonic waves are radiated in the direction of movement of the ship is explained, so the coefficient K _F ,
K _B is set so that the magnitude relationship thereof is K _F <K _B. Therefore, T _F <T _B , and the tracking gate width becomes shorter in the shallower direction and longer in the deeper direction, with the detected depth T ₁ as a reference. Here, T _F is
It functions as a gate when the previous measurement depth T ₁ is shallower, and T _B functions as a gate when it is deeper.

In addition, when emitting ultrasonic waves in the direction opposite to the direction in which the ship is traveling, the magnitude relationship of the coefficients K _F and K _B is
Set so that K _F > K _B. Therefore, T _F >
T _B , and the tracking gate width is the depth detected above.
Based on T ₁ , it becomes longer on the shallow side and shorter on the deeper side.

<Modifications of Embodiments> The above-mentioned embodiments are merely examples, and the present invention is not limited thereto, and can be implemented in other forms with appropriate modifications.

[Effects of the Invention] The present invention has been made to solve the above-mentioned problems, and the width of the tracking gate is selected according to the inclination of the seabed and the speed of the ship. It is effective in tracking the seabed reliably.

[Brief explanation of drawings]

FIGS. 1 to 4 are drawings for explaining the operation of the present invention, in which FIG. 1 is an explanatory diagram showing the influence of the movement of the ship and the inclination of the seabed on the propagation path of ultrasonic waves in front of the ship, and FIG. The figure is a waveform diagram showing the relationship between the time required from transmission to reception and the tracking gate, Figure 3 is a graph showing the relationship between the seabed inclination angle and T _R / T _L , and Figure 4
The figure is an explanatory diagram showing the influence of the movement of the ship and the inclination of the seabed on the propagation path of ultrasonic waves behind the ship. Figure 5 is an example of a tracking device for implementing the seabed tracking method of the ship speed measuring device of the present invention. Block diagram showing the 6th
The figure is a waveform diagram for explaining the operation of the above embodiment. 10... Ship speed measurement device, 11... Transducer/receiver, 1
2... Transmission/reception switching section, 13... Transmission section, 14... Receiving section, 15... Frequency detection section, 20... Sounding means, 21... Flip-flop, 22... Counter, 30... Tracking gate setting means, 31... Arithmetic circuit, 32, 33... Counter, 34... AND gate circuit.

Claims (1)

[Claims] 1. A ship speed measurement device that emits ultrasonic waves into the sea, receives reflected waves from the seabed, and detects ship speed using the Doppler effect, and the return time changes depending on the inclination of the seabed. This is a method of setting a tracking gate to receive the above reflected waves and tracking the reflected waves in response to changes in the ocean floor.The method calculates the time from transmission to reception and detects the measured depth. With the depth as a reference, the tracking gate width is set in the direction of travel so that it is shorter in the shallower direction and longer in the deeper direction, and in the opposite direction to the direction of travel, it is longer in the shallower direction and shorter in the deeper direction, and A seabed tracking method for a ship speed measuring device, characterized in that the tracking gate width is set as a function of the ship speed, and the gate width is set to expand or contract according to the ship speed. 2. A ship speed measurement device that emits ultrasonic waves into the sea, receives reflected waves from the seabed, and detects ship speed using the Doppler effect. A device that sets a receiving tracking gate to track reflected waves in response to changes in the seabed, and includes a sounding means that measures the time from transmission to reception and detects the measured depth; Based on this, in the direction of travel, the width of the tracking gate is set as a function of the above ship speed so that it is shorter in the shallow direction and longer in the deeper direction, and in the opposite direction, it is longer in the shallow direction and shorter in the deeper direction. What is claimed is: 1. A seabed tracking device for a ship speed measuring device, comprising a tracking gate setting means for setting a tracking gate and outputting a tracking gate start timing and a tracking gate end timing after the start of the next transmission.