SU133613A1 - Method for measuring parameters of sea waves - Google Patents

Description

Methods are known for measuring the parameters of sea waves using a pulse emitter and receiver installed at a certain height above the sea surface, equipped with an oscillographic pointer. However, the measurement results in similar ways are affected by the change in the height of the radio equipment above the excited surface during the radiation process. Therefore, a special directionality of the radiator and its stabilization in space is required.

In order to eliminate the above disadvantages, it is proposed to irradiate the disturbed surface of the sea with radio waves having a wavelength of one order with the sea wave length. The length of the sea waves is judged with respect to the lag time relative to the probe pulse of the maxima of two echo signals, one of which is reflected vertically from the rough surface of the sea, and the other at some acute angle. The height of the waves is determined by the ratio of the amplitudes of the indicated echoes and the time they are delayed relative to the probe pulse. The determination of the percentage of waves of different periods is made on the basis of an analysis of the shape of the echo signals reflected from the wave surface.

FIG. 1 shows the measurement of parameters of sea waves with a strict periodicity of the exciting surface; in fig. 2 - the same, with a deviation from strict periodicity; pas figs. 3- shows schematically the arrangement of pulses on the screen of an oscillographic device. Let the irradiated wave surface be strictly periodic with a wavelength (or period) L (Fig. I). At point A, there is an emitter emitting spherical radio waves with a wavelength comparable to the wavelength L of the surface under study. When the radio waves are reflected from the surface, a diverging stream of specularly reflected reflections appears at each of its irradiated points (flat lines with arrows

No. 133613-2 in FIG. 1) and the divergent flux of diffraction-reflected radio waves (dotted lines with arrows in FIG. 1).

Diffraction reflection is well-known for the periodicity of the surface and the direction of its propagation pn depends both on the angle of incidence φ and on the wavelength L of the surface: where, ± 2,. . . order of diffraction reflection Always one of the diffraction rays, reflected, for example, at point B, will necessarily pass through point A. Equality is the condition for such strict backward reflection.

This implies the connection between the angle of incidence φ and the relative wavelength of the surface, at which a strictly reverse diffraction reflection takes place, in the order of n: ssr - -j-, -2,.

On the other hand, if we use the pulse mode of the radiator at point A, the angle φ is associated with the delay time t of the pulse reflected at point B, and the time about the delay of the pulse reflected at point C (Fig. 1),

 2H C05tp

where R is the distance from the radiator to the reflecting point B; H-height of the radiator over the surface under study.

In this case, time is counted from the maximum of the probe pulse up to the maxima of the reflected pulses of the echo signals. From here comes the artificial link between the relative lag -t-

and the relative wavelength p of the surface: 7

, -2,. . .

To exclude ambiguity, it is advisable to choose the length

radio waves L within L X 2L; then it will be implemented

only diffraction reflection order. In this case.

t 1

° / tguzgu (1)

. 2L

Note that at point A only reflections come from point B and C, since radio waves diffracted and specularly reflected from other points do not enter it.

Thus, if a pulse transmitter and a receiver are located at point A, then measuring the delay time of the pulses reflected at points B and C relative to the probe pulse, one can determine the wavelength L of the excited surface.

The wave height h can be determined by the ratio of the amplitudes of the pulses, (p), reflected by points B and C, respectively. This ratio is related to the length of the radio wave, wave height A of the surface and the angle of incidence φ known from the wave diffraction theorem

J x

t

lg

 / 1- (||

on an uneven surface by the expression: - so8l f), (2)

where the / 1-function Bessel is of the 1st order; coscp is a real wave surface (for example, an agitated sea surface), which is not strictly periodic, changes the shape of the echo signals reflected from it. The nature of this change can be seen from the following considerations. Let deviation from strict periodicity

characterized by the magnitude of the relative change in wavelength-t-

surface. Since any non-periodic process is the imposition in certain ratios of periodic processes with various sets of periods, on each significant (compared to L) surface area there is a periodicity not only with the wavelength L, but also with the wavelength L - AL. Therefore, reflections will come to point A from both point B and some point B, which is located close to B (see Fig. 2). The diffracted radio wave from point B will correspond to the surface with the wavelength L, and from B- to the surface with the wavelength L-AL.

It should be borne in mind that in both B and B there is a periodicity with the wavelengths L and L, but the diffracted radio wave corresponding to the sea wave L-AL from point B does not fall into A- Similarly, from B diffracted the radio wave corresponding to the sea wave length L will also not fall into A.

In connection with this. that in A now the reflections come from two points (more precisely, on the entire explosive section), the reflected pulse will increase in duration by some value D, depending on the degree of deviation

from non-periodicity. -t- The magnitude of the expansion of the reflected pulse

D / can be approximated by differentiation of equation EQN2,: 7-flf Ttf, ifl -V TO Thus, the reflected pulse is somewhat diffused, as

shown in FIG. 3. At the same time, the expansion (blurring) of the pulse reflects the real state of the measured surface. By the magnitude of the pulse blurriness, one can approximately estimate the spectral composition of the measured agitated sea surface, i.e., the percentage of waves of different lengths. The position of the maximum reflected pulse

-J- corresponds to the wavelength of the surface of the sea.

Thus, the proposed method allows not only to determine the average values of the length and height of sea waves, but also provides information on the nature of the spread of these quantities.

Since the proposed method for measuring the parameters of sea waves is based on the dependence of the reflection angles of the diffracted radio waves on the wavelength L of the reflecting surface and on measuring these angles by comparing the delay times of the pulses reflected at different angles with respect to the probe pulse, the accuracy of measuring the wavelength L and

The ratio of -, - and does not depend on the height n of the radiator above the surface under study. The change in height I in the process of radiation also does not affect its results.

- 3 - # 133613

№ 133613

Subject invention

The method of measuring the parameters of sea waves using a pulse emitter and receiver installed at a certain height above the sea surface, equipped with an oscillographic indicator, is characterized in that, in order to eliminate the effect of the height of the radiator on the measurement results, the sea surface is irradiated with radio waves of the same order sea wavelengths, and their height or wavelength is judged by the ratio of amplitudes or delay times relative to the probe pulse of the maxima of two echo signals, Din of which is reflected vertically from the rough surface of the sea, and the other at an acute angle.

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