RU2024034C1 - Radar method of determination of parameters of sea surface and device to implement it - Google Patents

Abstract

FIELD: radio location. SUBSTANCE: radar method of determination of parameters of sea surface includes vertical emission of SHF radio pulses towards sea surface from flying vehicle when flying along line of main run of sea waves at altitude L < λ_min/2γ, where λ_min is minimum length of sea wave resolved by radar, γ is width of directivity diagram of radar aerial, measurement of speed V_fv and altitude of flight of flying vehicle, power P_Σ of transmitter of signals reflected from troughs r₁ and crests ρ₂ of sea waves, period T_s of signal reflected from sea surface and calculation of parameters of trochoidal approximation of sea surface by formulas:

, where λ = T_sV_fv is coefficient of directed action of aerial of radar, λ is length of radar wave. Device to implement this method has aerial 1, aerial switch 2, receiver 3, envelope detector 4, pulse transmitter 5, first indicator 6, first delay element 7, gating unit 8, second delay element 9, first key 10, first storage 11, first averager 12, first differentiator 13, first amplifier-limiter 14, second differentiator 15, second amplifier-limiter 16 former 17 of gating pulse, counting flip-flop 18, second key 19, second storage 20, second averager 21, second indicator 22, third differentiator 23, third amplifier-limiter 24, meter 25 of signal period, fourth differentiator 26, fourth amplifier-limiter 27, altimeter 28, meter 29 of of flying speed of flying vehicle, power meter 30, calculator 31 of parameters of sea surface. EFFECT: increased authenticity of determination of parameters of sea surface. 3 dwg

Description

 The invention relates to radio engineering and can be used in determining the parameters of the sea surface.

 Means (devices and methods) for measuring sea surface parameters are known. See, for example, a method of measuring the height of sea waves, implemented using a coherent pulse device (ed. St. USSR N 662888, class G 01 S 9/00).

 This method is based on measuring the values of the coefficient of variation of the square of the envelope of the reflected radio signal. The method provides a relatively accurate determination of the height of the sea waves, however, it does not completely restore the shape of the sea surface and its hardware implementation is quite complicated.

 A coherently pulsed radar for implementing this method additionally contains a large number of complex blocks: a coherent local oscillator, a phase shifter, phase detectors for sine and cosine quadrature components, a correction voltage isolation block, etc.

 The closest in technical essence to the proposed method is a method for determining the parameters of the sea surface, based on measuring the parameters of the sea surface by processing optical images of the sea surface in a special pool with glass walls [1].

 The closest in technical essence to the device proposed is a device for implementing the method, which contains installed on the aircraft transceiver antenna meter, the axis of the radiation pattern of which is oriented vertically down to the sea surface, a transmitter and a receiver with an envelope detector at the output to which the recording device is connected signal received when reflected from the sea surface. By recording the signal after processing, the ratio between the coherent and incoherent component of the signal reflected from the sea surface is judged, and then the height of the sea wave is determined from the graph for the used radio wave.

 The disadvantage of the described method and device is the lengthy process of obtaining parameters of the sea surface.

 The aim of the invention is to accelerate the process of determining the parameters of the sea surface.

; b =

, где λ=T_c˙ V_ла
D - коэффициент направленного действия антенны радиолокатора;
λ - длина волны радиолокатора.This is achieved by the method of determining the parameters of the sea surface, including determining the parameters a and b of the trochoidal approximation of the sea surface, the vertical emission of microwave radio pulses towards the sea surface from the aircraft during flight along the main run of sea waves at an altitude of L <λ _min / 2γ, where λ _min - minimum resolvable marine radar wavelength, γ - beamwidth radar antenna, measurement of V _la speed and altitude of the aircraft flight powerfully ρ _Σ ti transmitter and signal reflected from the troughs and crests ρ ₁ ρ ₂ sea waves of period T _with the signal reflected from the sea surface, and the calculation parameters a and b by the formulas: a =

; b =

where λ = T _c ˙ V _la
D is the directional coefficient of the radar antenna;
λ is the radar wavelength.

 The proposed method uses a description of the shape of the sea surface by trochoidal waves. The determination of the parameters a and b characterizing the specific shape of the trochoidal waves is possible by a radar method.

=

∫∫e^2iky(ζ,η)dζd

, (1) где

- амплитуда падающей электромагнитной волны:
λ - длина радиоволны:
y(ζ, η) - высота морской поверхности в зависимости от ζ и η координат поверхности.Indeed, the amplitude of the scattered signal in the case of a perfectly conducting surface in the far zone is calculated by the formula, which, taking into account the main term of the asymptotic representation of the Green's function, can be written

=

∫∫e ^{2iky (ζ, η)} dζd

, (1) where

- the amplitude of the incident electromagnetic wave:
λ is the length of the radio wave:
y (ζ, η) is the height of the sea surface depending on the ζ and η coordinates of the surface.

=

, (2) где σ_η - размер, разрешаемый ДН антенны на морской поверхности вдоль координаты η;
i= 1,2; причем i= 1 соответствует "блестящей" точке, находящейся во впадине морской волны, i=2 - на гребне.Then, after elementary transformations for the amplitude of the electromagnetic field reflected from the surface with a “brilliant” point (stationary phase point), we obtain:

=

, (2) where σ _η is the size allowed by the antenna bottom on the sea surface along the coordinate η;
i = 1.2; moreover, i = 1 corresponds to the "brilliant" point located in the trough of the sea wave, i = 2 - on the ridge.

, b =

(4) где ρ_Σ - мощность передатчика;
D - коэффициент направленного действия антенны радиолокатора;
λ - длина волны радиолокатора;
γ - ширина диаграммы направленности антенны радиолокатора;
L - высота полета летательного аппарата;
λ=T_c˙ V_ла (Т_с период сигнала; V_ла - скорость летательного аппарата).Moreover, the point ζ _i is determined from the equation
y _ζ ^I (ζ _i ) = 0 (3)
After calculating the power P falling into the receiver and using the trochoid equation, we obtain the following expressions for the trochoid coefficients:
a =

, b =

(4) where ρ _Σ is the transmitter power;
D is the directional coefficient of the radar antenna;
λ is the radar wavelength;
γ is the width of the radiation pattern of the radar antenna;
L is the flight altitude of the aircraft;
λ = T _c ˙ V _la (T _s signal period; V _la - aircraft speed).

At the selected flight altitude of the aircraft, which ensures the resolution of sea waves, the signals reflected from the sea surface will be periodic in nature, tracking the periodicity of sea waves with a period of T _s .

In this case, the reflection from the basins and ridges of the sea waves will correspond to the maxima in the recording of signals. Therefore, at a known speed of the aircraft, much higher speed of movement of sea waves, the signal period T _c and, consequently, the length of the sea wave can be determined from the reflected signal.

The flight altitude of the aircraft is selected based on the width of the radiation pattern of the radar antenna in a vertical plane passing through the direction of the main run of the waves, as well as from the specified minimum radar-permitted sea wave length
L <λ _min / 2γ (5) where λ _min is the minimum wavelength allowed by the radar. In the proposed device, which comprises aerial, antenna switch, receiver and envelope detector, a pulse transmitter, the output of which is connected to the second input of the antenna switch, a first indicator and a pulse transmitter made by microwave, the first delay element is connected in series, block gating, the second delay element, the first key, the first memory block and the first averaging block, the output of which is connected to the input of the first of the first indicator, the first differentiating unit, the first amplifier-limiter, the second differentiating unit, the second amplifier-limiter and the strobe driver, the output of which is connected to the control input of the strobing unit, the output of the envelope detector is connected to the inputs of the first delay element and the first differentiating unit , a counting trigger, the input of which is connected to the output of the strobe-pulse former, the second key is connected in series, the input of which is connected to the output of the second A delay element, a second memory unit, a second averaging unit and a second indicator, a third differentiating unit connected in series, a third limiter amplifier, the output of which is connected to the control input of the first memory unit, and a signal period meter, a fourth differentiating unit and a fourth limiter amplifier connected in series whose output is connected to the control input of the second memory block, the direct output of the counting trigger is connected to the control input of the first key and the input of the third differentiate its block, and the inverse output is to the control input of the second key and the input of the fourth differentiating block, an altimeter, an aircraft speed meter, a power meter, the input of which is connected to the output of the pulse transmitter, a sea surface parameters calculator, whose corresponding inputs are connected to the outputs of the period meter a signal, an altimeter, a first and second averaging unit, an aircraft speed meter, and a power meter.

 The proposed device is built on the basis of a pulsed radar. Since relatively small altitudes are required to achieve the required resolution of sea-wave elements, this imposes restrictions on the duration of the probe pulses. The duration of the probe pulses is chosen much shorter than the period of sea waves.

 In FIG. 1 is a graph explaining the proposed method; in FIG. 2 is a structural diagram of a device for implementing the method; in FIG. 3 is a timing diagram explaining the operation of the device.

 The device for implementing the method comprises aerial antenna 1, an antenna switch 2, a receiver 3 and an envelope detector 4, a pulse transmitter 5, the output of which is connected to the second input of the antenna switch, a first indicator 6, and the pulse is made by microwave, installed on the aircraft the first delay element 7, the strobe block 8, the second delay element 9, the first key 10, the first memory block 11 and the first averaging block 12, the output of which is connected in series to the input of the first indicator, the first differentiating unit 13, the first amplifier-limiter 14, the second differentiating unit 15, the second amplifier-limiter 16 and the driver of the strobe pulse 17, the output of which is connected to the strobing control unit, are connected in series with the output of the envelope detector a delay element and a first differentiating unit, a counting trigger 18, the input of which is connected to the output of the strobe-pulse former, the second key 19, the input of which is connected to the output of the second delay element, the second memory unit 20, the second averaging unit 21 and the second indicator 22, connected in series with the third differentiating unit 23, the third amplifier-limiter 24, the output of which is connected to the control input of the first memory unit, and the signal period meter 25, connected in series the fourth differentiating unit 26 and the fourth amplifier-limiter 27, the output of which is connected to the control input of the second memory block, the direct output of the counting trigger is connected to the control input of the first key and the input of the third differentiating unit, and the inverse output is to the control input of the second key and the input of the fourth differentiating unit, altimeter 28, speed meter of the aircraft 29, power meter 30, the input of which is connected to the output of the pulse transmitter, calculator of sea surface parameters 31, corresponding the inputs of which are connected to the outputs of the signal period meter, altimeter, first and second averaging units, aircraft speed meter, and power meter.

 The radar method for determining the parameters of the sea surface is as follows.

The aircraft is directed along the direction of the main wave run, and the flight altitude L is selected based on the condition
L <λ _min / 2γ, (6) where λ _min is the specified minimum resolved radar wavelength of the sea wave;
γ is the width of the radiation pattern of the antenna 1 of the radar
The probe microwave pulses generated by the transmitter 5, through the antenna switch 2, is fed to the antenna 1, the axis of which is oriented perpendicular to the sea surface (see Fig. 1).

 The electromagnetic energy pulses reflected from the sea surface are received by the same antenna 1 and through the antenna switch 2 are fed to the input of the receiver 3 and then to the input of the envelope detector 4. From the output of the envelope detector 4, a video signal (see the time diagram in Fig. 3, a) is fed to the input of the first delay element 7 and the input of the gating unit 8. A timing diagram of the voltage at the output of the first delay element 7 is shown in FIG. 3. This voltage is differentiated (see Fig. 3, b) using a differentiating circuit 13, subjected to amplification and limitation (see Fig. 3, c) using block 14, differentiate again (see Fig. 3, d) c using the second differentiating block 15 and from the obtained sequence of differentiated pulses, using the block 16, pulses of negative polarity are isolated (see Fig. 3, e), which are used to start the strobe-pulse shaper. Rectangular pulses at the output of block 17 (see Fig. 3, e) have a duration equal to twice the delay time of the signal in block 7, and the middle of each gate pulse corresponds to the time when the signal at the output of the delay element 7 reaches its maximum value. Rectangular pulses from the output of block 17 are fed to the control input of the gating stage 8.

 The amplitudes of the pulses at the output of block 8 (see Fig. 3, h) correspond to the maximum values of the signal at the output of the delay element 7.

 In addition, the pulses from the output of the shaper pulse generator 17 are fed to the input of the trigger 18, the first and second outputs of which receive pulses (see Fig. 3 k, l), with which they control the operation of the first key 10 and the second key 19. Pulses from the output of the gating block 13 serves on the second delay element 9, with which the pulses are delayed for the time required to ensure the operation of blocks 11 and 20.

 The signals from the output of the second delay element 9 (see Fig. 3, and) are fed to the signal inputs of the keys 10 and 19, with which pulses are separated (see Fig. 3m, n) corresponding to the trenches and crests of the sea waves. From the first and second outputs of flip-flop 18, pulses (see Fig. 3, k, l) are also fed to the inputs of the third and fourth differentiating blocks 23 and 26. Timing diagrams of pulses at their outputs are shown in FIG. 3, o, p. Pulses of positive polarity are isolated from these pulse sequences (see Fig. 3, p, c) using the fourth and third limiter amplifiers 27 and 24. Using the circuits 11 and 20, the pulse amplitudes at the outputs of the keys 10 are stored and 19 for a time equal to the period of sea waves (see Fig. 3, t, y). The pulses from the outputs of blocks 27 and 24 are fed to the control inputs of the memory circuits 11 and 20 before the arrival of the next pulse of the corresponding key. These pulses serve to reset the voltage on the memory circuits 11 and 20, and these pulses are ahead of the pulses at the outputs of the keys 10 and 19 by a time equal to the delay time of the pulses in the second delay element 9.

 Using block 25 measure the period of the signal reflected from the sea surface, for which the input of this block 25 serves the signals from the output of the third amplifier-limiter 24.

 From the outputs of memory blocks 11 and 20, the signals are fed to the inputs of the first and second averagers 12 and 21, respectively, from the outputs of which the voltages are removed (see Fig. 3 f, x), proportional to the average values of the electromagnetic field reflected from the crests and troughs of sea waves .

 Using a standard altimeter 28 and a speed meter 29, signals are generated corresponding to the flight altitude and aircraft speed.

 Using the power meter 30, a signal is generated corresponding to the average pulse power of the probe pulses. From the outputs of blocks 25, 28, 12, 21, 29, and 30, the signals are fed to a calculator 31 of the sea surface parameters, with the help of which the computational procedure defined by formulas (4) is implemented.

 In addition, from the outputs of the averagers 12, 21, the signals are sent to the first and second indicators 6 and 21, which provide information about the voltages at the outputs of the blocks 12, 21 in a form convenient for the observer to perceive.

 The readings of these indicators, combined with the readings of blocks 25, 28, 29, and 30, allow us to control the initial data for calculating the parameters of the sea surface using formulas (4).

 The proposed method for determining the parameters of the sea surface and a device for its implementation allow, in comparison with the prototype, to accelerate the process of determining the parameters of the sea surface.

Claims (2)

1. The radar method for determining the parameters of the sea surface, including determining the parameters a and b of the trochoidal approximation of the sea surface, characterized in that, in order to accelerate the process of determining the parameters of the sea surface, microwave radiation pulses vertically to the sea surface from the aircraft when flying along the main line sea waves
L <λ _min / 2γ,
where λ _min is the minimum resolved radar wavelength of the sea;
γ is the radar antenna radiation pattern width, the aircraft speed v _la and the flight altitude, the transmitter power P _Σ and the signals reflected from the basins P ₁ and ridges R _{2 of the} sea waves are measured, the period T _{from the} signal reflected from the sea surface, and the parameters are calculated a and b by the formulas
a =

;
b =

,
where λ = T _c ˙V _LA ;
D is the directional coefficient of the radar antenna;
λ is the radar wavelength.  2. A device for determining the paramaters of the sea surface, including a series-connected antenna, an antenna switch, an envelope detector and detector, a pulse transmitter, the output of which is connected to the second input of the antenna switch, a first indicator, characterized in that, in order to improve accuracy determining the parameters of the sea surface, the pulse transmitter is made by microwave, the first delay element is connected in series, the block is gated I, the second delay element, the first key, the first memory block and the first averaging block, the output of which is connected to the input of the first indicator, the first differentiating unit, the first limiting amplifier, the second differentiating block, the second limiting amplifier and the strobe driver, the output of which is connected to the control input of the gating block, the output of the envelope detector is connected to the inputs of the first delay element and the first differentiating block, a counting trigger, the input of which is connected to the strobe driver, a second key in series with the input connected to the output of the second delay element, a second memory unit, a second averaging unit and a second indicator connected in series with a third differentiating unit, a third limiter amplifier, the output of which is connected to the control input of the first block memory, and a signal period meter, connected in series to the fourth differentiating unit and the fourth amplifier-limiter, the output of which is connected to the control input of the second of the memory block, the direct output of the counting trigger is connected to the control input of the first key and the input of the third differentiating block, and the inverse output is connected to the control input of the second key and the input of the fourth differentiating block, an altimeter, an aircraft speed meter, a power meter, the input of which is connected to the output pulse transmitter, calculator of sea surface parameters, the corresponding inputs of which are connected to the outputs of the signal period meter, altimeter, first and second blocks of the device dneniya, meter aircraft and power meter speed.

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