JPS602633B2 - Wave height measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wave height measurement method for measuring the wave height of waves on the sea surface from a flying object such as an aircraft.

Generally, when measuring the wave height of waves on the sea surface, etc., a flying object such as an aircraft emits waves or particles such as light, electromagnetic waves, and sound waves that propagate through space at a finite speed. Measure the distance (altitude) to the next wave and calculate the distance (
The wave height is measured as a variation in the wave height.

Figure 1 shows one example of this, in which a transmitter 2 mounted on a flying object 1 such as an aircraft transmits waves such as light, fin magnetic waves, and sound waves, or a medium 5 such as particles to waves 7 on the sea surface. The medium 6 reflected from the wave 7 is received by the receiver 3, and the altitude is measured from the time taken from transmission to reception, and the variation is applied to the wave height of the wave 7. That's what I do. To explain this in more detail, if the distance (altitude) to the reflection point 25 on the sea surface is h, the speed of the medium is u, and the time from transmission to reception is t, then the distance h is [11
The value is given by the formula. h = science...m However, if the flying object 1 is made to fly at a constant altitude, and the measurement medium of waves and particles is sent and received one after another through the fin, and the altitude is recorded and displayed on the recorder 4, the sea level is measured. This is because the degree of measurement is changed by the height of the wave.

This situation is shown in FIG. This figure 3 records the change in altitude over time. Assuming that the sea surface is completely horizontal, the height a of the actual wave 9 changes from time to time with respect to the horizontal plane altitude 8 (in reality, this is usually considered to be the reference plane, that is, the altitude is zero). It turns out that it does. Here, if flying object 1 measures the altitude while flying horizontally at a constant altitude, section 1
0, a waveform centered at the horizontal plane altitude 8 is obtained. In other words, the center value of the vibration of wave 9 is
The distance from the wave 9 to the horizontal plane is h, and if the altitude distance h is subtracted as a DC component from the measurement result of the wave 9, only the vibration due to the wave 9 can be obtained, and the wave height a can be obtained. but,
It is difficult for the flying object 1 equipped with measuring instruments to fly at a constant altitude and constant attitude.

For example, as shown in FIG. 2, when the flying object 1 banks (rolls) by an angle Q as indicated by the dotted line, it is clear that the distance to the sea surface increases from h to h+Δh. However, △h is the value shown by formula (2). △h
= h. 3rd base ship..." [2, COSQ When the flying object 1 banks like this, the measurement of the wave height will also be at an altitude 1 higher than h by △h, as shown in section 11.
The waveform is centered around 2.

Furthermore, the flying object 1 generally moves up and down due to changes in atmospheric pressure, wind, etc. If there is vertical movement, the true altitude h itself will change. However, if such changes are sufficiently low compared to the observed frequency of the waves, they can be subtracted as DC components, but when measuring long wavelength waves with a slow flying object, the fluctuations due to the movement of the flying object may occur. When the frequencies of fluctuations and vibrations caused by waves are close to each other, it is difficult to distinguish them by frequency.

Therefore, in such cases, a gyro is usually used to detect roll pitch and other motions around the hoe, and an accelerometer is used to detect parallel motions such as vertical motion, and these are added to the altitude observation results. A means for adding corrections based on aircraft motion is established. FIG. 4 shows a block diagram of an example of a receiving section of a wave height meter that applies the correction.

In general, the circuit configuration and circuit operation of this type of wave height meter are such that the momentary altitude from the altitude measuring device 13 is determined by a roll pitch signal from a gyro 15 and a double integrator 17 from a vertical accelerometer 16 in a correction circuit 14. After subtracting the DC component corresponding to the altitude h mentioned above, the recorder 4 records and displays only the AC component, which is the vibration component, and from this recording and display, the wave height related to the wave is It is designed to let you know information such as a. However, such conventional devices require a highly accurate gyro and a vertical accelerometer, and also have problems such as difficulty in initializing the drift of the double integrator, making them expensive. An object of the present invention is to relatively easily measure wave height without the need for a gyro, an accelerometer, or an integrator, while eliminating the influence of the motion of a flying object.

If the frequency component of the vibration wave obtained from wave observation and the frequency component of the apparent distance variation due to the movement of the flying object are very far apart, the two components can be easily separated using a filter or the like.

Therefore, when measuring altitude, the present invention allows a transmission beam of an observation medium such as light or electromagnetic waves to be pulled through a bucket at high speed to observe waves at high speed.
Only Takagi's model is characterized by measuring the wave height by extracting it using a high-pass filter. The present invention will be explained below with reference to FIGS. 5 to 7.

FIG. 5 shows an example in which the wave height is measured from the flying object 1 using the present invention.

In this figure, it is assumed that the oscillation in the pitch direction of the flying object 1 is extremely large, and the case is shown in which the beam of the observation medium 5 is swept along the front and back direction of the flying object 1. . If we remove the stripe width of the beam on the sea surface when the beam is swept in this way, if this stripe is longer than the wavelength of wave 7 that we are trying to observe, we can detect the wave height of a wave that is less than the wavelength of wave 7. Is possible.

If this beam striping is performed at a much higher speed than the oscillation of the flying body 1, the information of the wave 7 will be obtained repeatedly at high speed, and the change in the measured altitude due to the wave 7 will be obtained as a high frequency component. FIG. 6 shows an example of the altitude information obtained in this way, and from the altitude information 9 including the influence of the wave 7, a signal of high frequency components is obtained in the section 10 around the horizontal plane altitude h, Furthermore, in section 11, the altitude change of the flying object 1 indicates a case where there is a change in roll. In section 11, high frequency components are superimposed on gentle fluctuations. Extracting only the high frequency component from such a waveform can be easily performed using a Takagi pass filter. Returning to FIG. 5 again, when the altitude is measured by sweeping the beam as shown, an error in distance occurs due to swinging the beam. Here, if the distance data obtained when the beam is swung by an angle of 6 from the vertical line is R, then a tidal type relationship is established between it and the horizontal height h. h=RCoS8 Therefore, in order to accurately measure the altitude, it is necessary to perform a correction calculation as shown in equation '3' using the obtained Puhi distance and the deflection angle of the beam at that time.

Moreover, this calculation needs to be performed every time the angle 8 changes and a new distance is obtained. However, the angle 8
Since is a known value, this calculation can be easily performed both analogously and digitally. The above explanation assumes that there is no fluctuation in the pitch direction, but if there is fluctuation in the pitch direction, it is necessary to stabilize it with a stabilizing platform to eliminate the influence of the pitch, or [3] It is necessary to perform a correction calculation of the formula including the pitch.

Therefore, in this case, a gyroscope is required to detect pitching. For correction calculations including pitch, 88 may be substituted for 8 in equation '3}, where 8 is the pitch angle. FIG. 7 shows a block diagram of an embodiment of the present invention for performing high-speed beam sweeping and measuring wave height.

This block diagram explains the case in which correction in the pitch direction is included as described later, but if the axis in the direction in which the beam is swung by the flying object 1 is stable, there is no need to take this into account. . To explain the operation of the circuit shown in FIG. 7, the transmitter 19 swings the beam toward the sea surface at high speed within a certain fixed angle 8 in response to the sweep signal from the green signal generator 20.

On the other hand, the receiver 18 receives media such as light and electromagnetic waves reflected from the sea surface, and the distance R from this received signal to the waves on the sea surface is calculated. Of course, it is clear that this distance R has not been completely corrected yet. The distance R is then input to the correction calculation circuit 22, where it is corrected to the original vertical altitude, and this correction is based on signals from the gyro 15 and the sweep signal generator 20. The gyro 15 detects the rotational movement of the flying body in the direction of rice braking,
The rotation detection force is added together with the sweep signal 8 in an adder 21, and the added signal 88 is used in a correction calculation circuit 22.
The amount of correction is adjusted accordingly. In this case, it is clear that the gyro 15, and therefore also the adder 21, can be omitted if the axial movement of the flying object in the bridge direction is negligible. When such a correction is performed by the correction calculation circuit 22, the vertical altitude h
is obtained. This vertical height h information has a waveform as shown in FIG. 6, as already explained. In order to extract only high frequency components from such a waveform, it is passed through a high-pass filter 23. Since only the high wave component passing through the filter 23 is recorded and displayed on the recorder 24, the wave height on the sea surface can be known from this. In the above explanation, the direction of the transmitted beam is swung along the traveling direction of the flying object, but it is not limited to this, and the direction in which the beam sweeps can be any direction that can receive a predetermined wavelength is sufficient. be.

As described above in detail, the present invention rapidly changes the direction of the fin beam emitted from the flying body, sweeps the wavefront at high speed over a certain width, and collects the beam reflected from the wavefront. After the pulse height information including high frequency components obtained based on the above is corrected, only the high frequency components are extracted, thereby obtaining only the desired pulse height information.

If the wave height is recorded and displayed in this way, the vertical accelerometer, double integrator, etc. that were conventionally required can be omitted, and in some cases, the gyro can also be omitted. According to the present invention, measurement of wave height can be performed easily and at low cost.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are explanatory diagrams of the secondary wave height measurement method. FIG. 4 is a block diagram of the receiving section used for reception using the conventional wave height measurement method. FIGS. 5 and 6 FIG. 7 is an explanatory diagram of the present invention, and FIG. 7 is a block diagram of a transmitting/receiving section in an embodiment of the present invention. 1...Flying body, 2,19...Transmitter, 3,18
...Receiver, 4,24...Recorder, 7...Wave, 1
5... Gyaro, 20... Sweep signal generator, 21.
. . . Adder, 22 . . . Correction calculation circuit, 23 . . . Takagi pass-through filter. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 When measuring the altitude from the flying object to the sea surface,
The radiation direction of a transmitted beam such as light or electromagnetic waves from a flying body is changed at high speed to sweep the wave surface over a certain width, and the reflected beam from the wavefront of the swept transmitted beam is received by the flying body. By extracting only the wave height information of the high frequency component from the apparent height change axis of the low frequency component due to the movement of the flying body itself, we can calculate the wave height of the waves on the sea surface. A wave and sea measurement method characterized by the measurement of waves and oceans.