RU2537384C1 - Polarisation-modulation method of radar measurement of roll angle of airborne vehicle, and device for its implementation - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: method and device apply radar navigation devices. A polarisation-modulation method of radar measurement of a roll angle of an airborne vehicle and a device for its implementation consists in the fact that a passive polarisation-anisotropic radar reflector of electromagnetic waves with horizontal linear proper polarisation is located at a point with known coordinates. The radar reflector is irradiated from the airborne vehicle board by a linearly polarised electromagnetic wave the polarisation plane of which rotates at some speed. The reflected electromagnetic wave, the polarisation of which coincides with polarisation of the emitted electromagnetic wave, is received on the board of the airborne vehicle. As per measured phase (at the receiver output) of spectrum component with double rotation speed of the polarisation plane of received signals there determined is a roll angle of the airborne vehicle.

EFFECT: avoiding constant build-up of a measurement error in course of time.

2 cl

Description

The invention relates to radio navigation and can be used in flight navigation systems for the orientation of the aircraft (LA) when approaching instruments.

Known methods and devices for measuring the roll angle of an aircraft are based on the use of inertial navigation systems, in particular gyroscopic orientation systems [1-4]. Such measurement methods and devices that implement them have a number of disadvantages. First, over time, there is a constant accumulation of measurement errors and for one hour of flight it is a unit of degrees [2, 3]. Secondly, if the aircraft develops significant overloads, then the gyroscope’s own precession rate increases, which in some cases can lead to a complete loss of its performance [2].

Since the known methods for measuring the roll angle of aircraft and devices implementing them are based on a different physical principle, in comparison with the claimed ones, they cannot be considered as analogues, since they do not have common features.

The essence of the proposed polarization-modulation method of radar measurement of the roll angle of the aircraft is as follows.

At a point with known coordinates, a polarization-anisotropic passive radar reflector with horizontal linear polarization of its own, made in the form of a trihedral angular reflector (UO), consisting of three planar mutually perpendicular metallic or metallized triangular faces of the same size, significantly exceeding the wavelength in which the opening is located vertically oriented polarizing grating of round metal parallel rods (wires) [5, 6].

It is known [5, 6] that the trihedral UO itself is a polarization-isotropic object, i.e. when a plane linearly polarized electromagnetic wave is incident upon it after triple reflection, a plane wave is formed, propagating in the direction opposite to the direction of incidence, while the reflected wave also remains linearly polarized with the same orientation angle, i.e. It turns out to be polarized in parallel to the incident wave. Thus, a trihedral UO behaves like a flat metal plate under normal incidence and therefore it is considered as a polarization-isotropic object [5, 6], and its scattering matrix (MP) in a linear polarizing basis has a unit diagonal shape [6]:

$$[S_0]=\lambda \cdot \left[\begin{array}{cc}\mathrm{one}& 0\\ 0& \mathrm{one}\end{array}\right],\left(\mathrm{one}\right)$$

where λ is the absolute value of the eigenvalue (value) MP and has an infinite number of pairs of eigenvectors (eigenpolarizations) corresponding to it, for which the square of the λ ² module corresponds to the maximum possible effective scattering surface (area) ESR σ _{m of a} trihedral EO, i.e. . λ ² = σ _m .

To give a polarization-isotropic trihedral UO with MP (1) polarization-anisotropic properties, a vertically oriented polarizing grating of parallel metal rods (or wires) with a grating pitch A = 5 mm and a rod diameter B = 0.64 mm is placed in the UO opening (5, 6 ]. The parameters of the polarization lattice (the diameter of the rods (wires) B and the lattice pitch A) are chosen such that the component of the electric field vector of the incident electromagnetic wave with a length λ = 3.2 cm, the plane of polarization of which is orthogonal to the lattice rods (wires) and is in the horizontal plane, passes through the polarization lattice, practically unchanged, and after triple reflection from the faces of the trihedral UO, the electromagnetic wave propagates in the direction opposite to the direction of incidence. In this case, the reflected electromagnetic wave is horizontally linearly polarized regardless of the orientation angle of the plane of polarization of the incident wave, while the component of the electric field vector, the plane of polarization of which is parallel to round rods (or wires) and is in the vertical plane, is completely reflected from the polarization grating as a flat metal plate [5]. Thus, a trihedral UO with a vertically oriented polarization lattice located in the UO aperture plane is considered as a polarization-anisotropic object [5, 6], and its MP in its own linear polarization basis [^^^] has the form [5, 6]:

$$[S_{\mathrm{one}}]=\left[\begin{array}{cc}{\lambda }_{\mathrm{one}}& 0\\ 0& 0\end{array}\right],\left(2\right)$$

where λ ₁ is the modulus of the eigenvalue MP.

- эффективной площади рассеяния (ЭПР) σ. При этом собственное число λ₂ равно нулю, а ориентация собственного вектора (или собственной поляризации), соответствующего собственному числу λ₁ вырожденной MP (2), соответствует геометрической ориентации вибратора. Тогда вырожденная MP (2) в собственном линейном поляризационном базисе $$\left[{\overrightarrow{e}}_x,{\overrightarrow{e}}_y\right]$$

поляризационно-анизотропного трехгранного УО может быть представлена в виде [6, 8]The physical meaning of degenerate MP (2) becomes clear if we turn to the two-vibrator scattering model of a stable radar target [6, 7], namely: the eigenvalue MP (2) λ ₁ has the meaning of the effective length of the vibrator, and its square $${\lambda }_{\mathrm{one}}^2$$

- effective scattering area (EPR) σ. In this case, the eigenvalue λ ₂ is equal to zero, and the orientation of the eigenvector (or eigenpolarization) corresponding to the eigenvalue λ _{1 of the} degenerate MP (2) corresponds to the geometric orientation of the vibrator. Then the degenerate MP (2) in its own linear polarization basis $$\left[{\overrightarrow{e}}_x,{\overrightarrow{e}}_y\right]$$

polarization-anisotropic trihedral UO can be represented in the form [6, 8]

$$[S_{\mathrm{one}}]=\sqrt{{\sigma }_m}\cdot \left[\begin{array}{cc}\mathrm{one}& 0\\ 0& 0\end{array}\right]\left(3\right)$$

- максимально возможная ЭПР поляризационно-анизотропного трехгранного УО при облучении его линейно горизонтально поляризованной электромагнитной волной.Where $${\sigma }_m={\lambda }_{\mathrm{one}}^2$$

- the maximum possible ESR of a polarization-anisotropic trihedral UO when irradiated with a linearly horizontally polarized electromagnetic wave.

From analysis (3), it follows that in its own linear polarization basis, the degenerate MP (3) of the trihedral UO, in the aperture of which a vertically oriented polarization lattice of round parallel metal rods is placed, is equivalent to the MP pronounced polarization-anisotropic radar object, which is a horizontal vibrator.

будет всегда совпадать с горизонтальной плоскостью. При этом интенсивность отраженной и, соответственно принятой на борту ЛА, электромагнитной волны будет изменяться с частотой 2Ω, от некоторого максимума, при совпадении горизонтальной линейной поляризации излученной электромагнитной волны с собственной горизонтальной линейной поляризацией поляризационно-анизотропного УО, до минимума, при вертикальной ориентации плоскости поляризации излученной электромагнитной волны. Однако эти условия соблюдаются только в том случае, когда поперечная ось ЛА находится в горизонтальной плоскости, т.е. крен ЛА отсутствует и, соответственно, излученная горизонтально линейно поляризованная электромагнитная волна и принятая на борту ЛА электромагнитная волна совпадают по поляризации и их плоскости поляризации совпадают с горизонтальной плоскостью (плоскостью горизонта). В тех случаях, когда крен ЛА отличен от нуля, т.е. поперечная ось ЛА не находится в горизонтальной плоскости, то угловые положения плоскости поляризации излученной линейно поляризованной электромагнитной волны, при которых достигаются максимум или минимум интенсивности отраженной от УО электромагнитной волны и, соответственно, принятой на борту ЛА электромагнитной волны, смещаются и определяются креном ЛА. При этом плоскость поляризации отраженной от УО электромагнитной волны по прежнему горизонтальная и находится в горизонтальной плоскости, а плоскость поляризации принимаемой на борту ЛА электромагнитной волны не совпадает с горизонтальной плоскостью и ее угол ориентации определяется величиной угла крена ЛА, что определяет физическую основу измерений его угла крена.Then, irradiating a polarized-anisotropic UO with MP (3) linearly polarized by an electromagnetic wave from the aircraft, the vector of the electric field E which rotates with frequency Q, reflected from the faces of a trihedral UO electromagnetic wave regardless of the angle of orientation of the plane of polarization of the incident wave will always be polarized linearly horizontal and, accordingly, the vector of the electric field intensity reflected from the electromagnetic field of the electromagnetic wave $$\overrightarrow{E}$$

will always match the horizontal plane. In this case, the intensity of the reflected and, accordingly, accepted on board the aircraft, electromagnetic wave will change with a frequency of 2Ω, from a certain maximum, when the horizontal linear polarization of the radiated electromagnetic wave coincides with its own horizontal linear polarization of the polarization-anisotropic EO, to a minimum, with the vertical orientation of the plane of polarization radiated electromagnetic wave. However, these conditions are met only when the transverse axis of the aircraft is in the horizontal plane, i.e. the aircraft roll is absent and, accordingly, the horizontally linearly polarized electromagnetic wave emitted and the electromagnetic wave received on board the aircraft coincide in polarization and their plane of polarization coincides with the horizontal plane (horizon plane). In cases where the roll of the aircraft is non-zero, i.e. Since the transverse axis of the aircraft is not in the horizontal plane, the angular positions of the plane of polarization of the emitted linearly polarized electromagnetic wave, at which the maximum or minimum intensity of the electromagnetic wave reflected from the UO and, accordingly, the electromagnetic wave received on board the aircraft is reached, are shifted and determined by the aircraft roll. In this case, the plane of polarization of the electromagnetic wave reflected from the EO is still horizontal and is in the horizontal plane, and the plane of polarization of the electromagnetic wave received on board the aircraft does not coincide with the horizontal plane and its orientation angle is determined by the roll angle of the aircraft, which determines the physical basis for measuring its roll angle .

которой совпадает с одной из собственных поляризаций УО, позволяет максимизировать или минимизировать уровень отраженной и, соответственно, принятой на борту ЛА, электромагнитной волны.Thus, by irradiating the polarization-anisotropic trihedral UO with an electromagnetic wave, the orientation of the electric field strength vector $$\overrightarrow{E}$$

which coincides with one of the own polarizations of the OO, allows you to maximize or minimize the level of reflected and, accordingly, accepted on board the aircraft, electromagnetic waves.

Then the rotation of the plane of polarization of the emitted electromagnetic wave with a frequency of Ω will lead to amplitude modulation with a frequency of 2Ω taken on board the electromagnetic wave of the aircraft. Obviously, separation of the spectral component from the amplitude of the received signal at the output of the receiver at a frequency of 2Ω and measuring its phase relative to the doubled angular position of the plane of polarization of the emitted electromagnetic wave will make it possible to measure the roll angle of the aircraft.

We establish a relationship between the amplitude and phase of the spectral component at a frequency of 2Q and the roll angle of the aircraft.

To establish this connection, we use the well-known [9] formalism of vectors and Jones matrices.

которого совпадают соответственно с поперечной и вертикальной осями ЛА, можно найти, с учетом (3), с помощью преобразований вида:Then the signal at the input of the receiver in its own linear orthogonal polarization basis, unit unit vectors $$\left[{\overrightarrow{e}}_x,{\overrightarrow{e}}_y\right]$$

which coincide respectively with the transverse and vertical axes of the aircraft, can be found, taking into account (3), using transformations of the form:

$${\overrightarrow{\stackrel{.}{E}}}_{\mathrm{at}x}=C\cdot \left\{\left[P\right]\left[R(-\alpha )\right]\left[R(\mp \gamma )\right]\cdot \left[S_{\mathrm{one}}\right]\left[R(\pm \gamma )\right]\left[R(\alpha )\right]\cdot \overrightarrow{\stackrel{.}{E}}\right\},\left[\mathrm{four}\right]$$

- вектор Джонса исходной горизонтально линейно поляризованной излучаемой электромагнитной волны, совпадающей с горизонтальной плоскостью и поперечной осью ЛА, представленный в собственном линейном поляризационном базисе $$\left[{\overrightarrow{e}}_x,{\overrightarrow{e}}_y\right]$$

,Where $$\overrightarrow{\stackrel{.}{E}}=\left[\begin{array}{c}\mathrm{one}\\ 0\end{array}\right]$$

- Jones vector of the initial horizontally linearly polarized emitted electromagnetic wave, coinciding with the horizontal plane and the transverse axis of the aircraft, presented in its own linear polarizing basis $$\left[{\overrightarrow{e}}_x,{\overrightarrow{e}}_y\right]$$

,

- оператор вращателя линейной плоскости поляризации излучаемой электромагнитной волны по направлению движения часовой стрелки на угол α=Ωt (Ω - частота вращения, t - время), $$[R(\alpha )]=\left[\begin{array}{cc}\cos \alpha & \sin \alpha \\ -\sin \alpha & \cos \alpha \end{array}\right]$$

- the operator of the rotator of the linear plane of polarization of the emitted electromagnetic wave in the clockwise direction at an angle α = Ωt (Ω is the rotation frequency, t is time),

- прямой оператор поворота на угол крена ЛА ±γ, $$[R(\pm \gamma )]=\left[\begin{array}{cc}\cos \gamma & \pm \sin \gamma \\ \mp \sin \gamma & \cos \gamma \end{array}\right]$$

- the direct operator of rotation at an angle of heel LA ± γ,

+ γ is the positive angle of heel when the right wing or the transverse axis of the aircraft is below the horizontal plane,

-γ is the negative angle of heel when the right wing or the transverse axis of the aircraft is above the horizontal plane,

- матрица рассеяния поляризационно-анизотропного трехгранного УО с горизонтальной линейной собственной поляризацией, $$S_{\mathrm{one}}=\left[\begin{array}{cc}\mathrm{one}& 0\\ 0& 0\end{array}\right]$$

- scattering matrix of a polarization-anisotropic trihedral UO with horizontal linear intrinsic polarization,

- обратный оператор поворота на угол крена ЛА $$\mp \gamma$$

, $$[R(\mp \gamma )]=\left[\begin{array}{cc}\cos \gamma & \mp \sin \gamma \\ \pm \sin \gamma & \cos \gamma \end{array}\right]$$

- reverse operator of rotation by the angle of heel of the aircraft $$\mp \gamma$$

,

- оператор вращателя плоскости поляризации принимаемой на борту ЛА электромагнитной волны на угол -α. $$[R(-\alpha )]=\left[\begin{array}{cc}\cos \alpha & -\sin \alpha \\ \sin \alpha & \cos \alpha \end{array}\right]$$

- the operator of the rotator of the plane of polarization of the electromagnetic wave received on board the aircraft at an angle of -α.

- оператор линейного поляризатора (переход с круглого или квадратного волновода на прямоугольный волновод) с горизонтальной линейной собственной поляризацией, совпадающей с поперечной осью ЛА, $$P=\left[\begin{array}{cc}\mathrm{one}& 0\\ 0& 0\end{array}\right]$$

- the operator of a linear polarizer (transition from a round or square waveguide to a rectangular waveguide) with a horizontal linear intrinsic polarization coinciding with the transverse axis of the aircraft,

C is a constant value taking into account the potential of the transmitter, the distance from the transmitter to the polarization-anisotropic VO and vice versa, its maximum possible ESR σ _m and the sensitivity of the receiver.

Having done the necessary matrix transformations in (4), we obtain

$${\overrightarrow{\stackrel{.}{E}}}_{{}_{\mathrm{at}x}}=\mathrm{FROM}\cdot {\cos }^2(\alpha \pm \gamma ).\left(5\right)$$

Accordingly, the amplitude of the signal at the output of the receiver having a logarithmic amplitude characteristic and a linear detector, taking into account α = Ωt, will be equal to:

$$E_{\mathrm{at}sx}(\Omega t)=\lg C+\lg \frac{\mathrm{one}}{2}\cdot [\mathrm{one}+\cos (2\Omega t\pm 2\gamma )].\left(6\right)$$

From analysis (6), we see that in the spectrum of the envelope of the output signal of the logarithmic receiver there is only a spectral component at a frequency of 2Ω and its phase φ _2Ω is determined only by the roll angle γ of the aircraft, regardless of the transmitter power, the distance from the transmitter to the UO and vice versa, the EPR of the UO, and receiver sensitivity.

The amplitude of this spectral component can be found as

$$A_{2\Omega t}=\frac{\mathrm{one}}{\pi }{\displaystyle \underset{0}{\overset{2\pi }{\int }}{E}_{\mathrm{at}sx}(\Omega t)\cdot \mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">cos</figure-callout>}2\Omega td(\Omega t),\left(7\right)}$$

Or, taking into account (6) and the known relation

$${\displaystyle \underset{0}{\overset{2\pi }{\int }}\ln (\mathrm{one}+\cos x)\cdot \cos xdx=2\pi },\left(8\right)$$

and also taking into account the fact that the signal level in the presence of a logarithmic receiver is usually measured in decibels, we find that the amplitude of the spectral component is maximum and equal to

$$A_{2\Omega t}=40\lg e\approx 17.37dB,\left(9\right)$$

and its phase φ _2Ω , taking into account (6), is related to the angle of heel γ LA by the ratio:

$$\gamma [R\mathrm{but}d.]=\pm \frac{{\mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">\varphi </figure-callout>}}_{2\Omega }}{2}[R\mathrm{but}d].\left(10\right)$$

The use of the claimed combination of features for measuring the angle of heel γ LA in the known solutions by the author was not found.

Figure 1 shows a passive polarization-anisotropic radar reflector of electromagnetic waves with a horizontal linear intrinsic polarization, located at a point with known coordinates, and made in the form of a trihedral UO (position 1 front view), in the opening of which is placed a vertically oriented polarizing grating made of round metal parallel rods (position 2) with a grid pitch of A = 5 mm and a diameter of rods of B = 0.64 mm. Position 3 is a side view.

Figure 2 presents a structural electrical diagram of a device that implements the proposed polarization-modulation method of radar measurement of the angle of heel of an aircraft located on board the aircraft. The device includes a transmitter 1, an antenna switch 2, a linear polarizer 3, a polarization plane rotator 4, a transceiver antenna 5, a synchronizer 6, a logarithmic receiver 7, a master oscillator 8, a synchronous step micromotor 9, an angular position sensor for the half-wave phase plate λ / 2 10 , tracking range meter 11, time selector 12, automatic gain control (AGC) unit 13, reference signal generating unit 14, balanced detector 15, peak detector 16, band-pass filter 17, phase detector 18, indicator roll angle 19.

Figure 3 presents the structural electric circuit of a tracking range meter (LED) 11. The LED contains a search and capture circuit 20, a time discriminator 21, an extrapolator 22, a servo pulse generator 23, a controlled time delay unit 24.

The device operates as follows.

The synchronizer 6 generates a periodic sequence of video pulses of the start of the transmitter 1 (IPP). The transmitter 1 at the time of receipt of its input from the output of the synchronizer 6 generates a radio pulse, which through the antenna switch (AP) 2, a linear polarizer 3 with a horizontal linear intrinsic polarization coinciding with the transverse axis of the aircraft, made in the form of a transition from a rectangular waveguide to a round the waveguide and the rotator of the plane of polarization 4, enters the antenna 5 and is radiated in the direction of the polarization-anisotropic passive radar reflector.

The rotator of the plane of polarization 4 rotates at a frequency Ω of the plane of polarization of the emitted radio pulses, and the rotation frequency Ω is much less than 2πF _n , where F _n is the repetition frequency of the radio pulses, which is necessary for matching the polarizations of the emitted and received signals. The rotation of the plane of polarization of the emitted signal in the rotator 4 is due to mechanical rotation with a frequency of Ω ₁ = Ω / 2 section of a circular waveguide with a half-wave λ / 2 phase plate mounted in it. The frequency of mechanical rotation Ω _{1 of the} half-wave phase plate is selected taking into account the fact that the plane of polarization of the electromagnetic wave emitted by the antenna 5 in the direction of the radar reflector will, as is known [6, 7], rotate by twice the orientation angle of the half-wave phase plate. Therefore, continuous mechanical rotation with a frequency of Ω _{1 of the} half-wave phase plate will cause the plane of polarization of the emitted linearly polarized electromagnetic wave to rotate continuously with a frequency of Ω = 2Ω ₁ . The rotation of the rotating section of the circular waveguide is provided by a synchronous stepper micromotor 9, mechanically connected using a gear gear 1: 1 with a section of a circular waveguide. The rotation frequency of the circular waveguide section Ω ₁ is set by the master oscillator 8, which generates a continuous sequence of pulses that are converted into a rotation of the rotor shaft of the synchronous stepper micromotor 9 by a certain angle. Since the rotor shaft of the synchronous stepless micromotor is mechanically connected to the rotating section of the circular waveguide with a half-wave phase plate mounted in it, and the sequence of pulses generated by the master oscillator 8 is fed to the control input of the synchronous stepwise micromotor 9 continuously, the half-wave phase plate with a frequency Ω ₁ . To obtain information about the angular position of the half-wave phase plate, the rotor shaft of the synchronous step micromotor 9 is simultaneously mechanically connected to the angular position sensor of the phase plate 10, made on the basis of selsyn, whose axis is mechanically connected by means of a gear transmission with a step micromotor 9. The output voltage of the selsyn is detected in the balanced detector 15, after which a reference sinusoidal voltage with a doubled rotation frequency is formed at its output in the block for generating the reference signal 14 I have a polarization plane of 2Ω.

Electromagnetic waves reflected by a polarization-anisotropic radar reflector, the plane of polarization of which always coincides with the horizontal plane, are received by antenna 5 and, having passed the rotating section of the circular waveguide with the half-wave phase plate 4 mounted inside, enter the linear polarizer 3, where a horizontally linearly polarized component is extracted, which through the antenna switch 2 is fed to the input of the logarithmic receiver 7 with a linear detector. In the receiver 7, the signal is amplified to the required level and, after detection, is fed to the signal input of the temporary selector 12. Rotation of the plane of polarization of the electromagnetic waves emitted from the polarization-anisotropic radar reflector of electromagnetic waves with a frequency of Ω, which are reflected from the polarization-anisotropic radar reflector, leads to The output of the logarithmic receiver generates a signal having the form (6), modulated in amplitude by twice the rotation frequency of the polarization plane 2Ω.

At the same time, the output SPDs from the output of the synchronizer 6 go to the first input of the tracking range meter 11, and reflected pulses from the polarization-anisotropic radar reflector arrive to its second input from the output of the temporary selector 12. Tracking range meter 11 (LED) is designed to automatically track the delay τ = 2R / c, proportional to the current range R (t) to the radar reflector and the formation of tracking pulses (SI) at its output, the temporary position of which displays a smooth change in the range to the radar reflector. SI arrive at the control input of the temporary selector 12, made in the form of a controlled key, which is opened by the tracking pulse of the LED only for the signal of the monitored radar reflector, which is normalized using AGC 13. The generalized structural electrical circuit of the LED is presented in figure 3 and is made according to the well-known classical circuit [10-12], widely used in radar tracking targets in range [13].

The operation of the LED 11 is as follows.

The reflected pulses (OI) from the output of the temporary selector 12 are supplied to the first input of the temporary discriminator 21, and the second impulses of follow-up pulses (SI) from the output of the follower pulse generator 23. In the temporary discriminator 21, the temporary position of the OI and SI is compared. After that, the time discriminator 21 outputs to the input of the extrapolator 22 a mismatch signal ΔU in analog form. To exclude the dependence of the mismatch signal ΔU on the intensity of the optical radiation, a normalization is performed using the AGC circuit 13 according to the signal of the monitored radar reflector, for which the time range selector 12 is gated by a tracking pulse. Under the influence of the mismatch signal ΔU, the extrapolator 22 generates a control voltage U _R supplied to the control input 2 of the controlled time delay unit 24, and the input from the synchronizer 6 is supplied to its first input. Under the influence of the control voltage U _R , the time delay of the IZ changes. The value of the time delay of the SPD is determined by the value of the control voltage U _R from the output of the extrapolator 22. The delayed pulses act on the shaper of the tracking pulses 23, which generates tracking pulses at its output. The time delay of the tracking pulses can be considered as the expected delay of the signal reflected by the radar reflector or, otherwise, as an extrapolated estimate for the current period of the range finder’s operation, obtained from the results of measurements of previous cycles. From the output of the servo pulse generator 23, the servo pulses are simultaneously fed to the time discriminator 21 and to the control input of the temporary selector 12, as a result of which the time mismatch between the OI and SI is compensated and, thus, the loop ring of the range tracking system is closed.

The tracking or measurement mode is preceded by the search and capture mode. The initial alignment of the tracking pulses with the pulses reflected from the radar reflector is carried out using the search and capture circuit 20. In the search mode, the tracking ring is broken, since the temporary position of the OI is unknown and the mismatch between the OI and SI is so large that they do not overlap. In this case, the search and capture circuit 20 acts on the extrapolator 22, periodically changing the control voltage U _R at the output of the extrapolator 22 linearly according to a sawtooth law, and thereby slowly shifting the tracking pulses in time within the range of measured ranges. This movement is carried out periodically with a period T _p repetition of the probe pulses in the interval of a priori delays. As soon as the tracking pulses are combined with the pulses reflected from the radar reflector during the slow range adjustment, the capture automaton is triggered, switching the LED from the search mode to the tracking mode of the radar reflector in range. In this case, the search circuit is disconnected from the extrapolator 22 and the control voltage U _R at its output is proportional to the range to the radar reflector. Thus, the time range selector 12, made in the form of a key, is opened by a tracking range pulse only for reflected pulses from the monitored radar reflector, which are then normalized in receiver 7 using AGC 13.

From the output of the temporary selector 12, the pulses reflected from the radar reflector are fed to the input of the peak detector 16, where the received signal is extracted and stored for a time equal to the period of the emitted pulses. From the output of the peak detector 16, the signal is fed to the input of the bandpass filter 17, tuned in accordance with expression (6) to twice the frequency of rotation of the plane of polarization 2Ω. The band-pass filter 17 selects the spectral component at a frequency of 2Ω and this signal is fed to the first signal input of the phase detector 18, and the reference signal with a doubled frequency of rotation of the polarization plane 2Ω is supplied to its second input from the output of the reference signal generating unit 14. In the phase detector 18, the phase φ _{2Ω of the} spectral component is measured at a frequency of 2Ω, from which the roll angle γ of the aircraft is determined. From the output of the phase detector 18, a signal proportional to the sine of the phase difference of the input signals is supplied to indicator 19, the scale of which is calibrated taking into account relation (10) in degrees of roll angle γ LA.

In the 3 cm wavelength range of the claimed device for measuring the angle of heel of the aircraft can be implemented as follows.

The main functional elements of the measuring device, including: transmitter 1, antenna switch 2, transceiver antenna 5, synchronizer 6, logarithmic receiver 7, time selector 12, automatic gain control unit (AGC) 13, balanced detector 15, peak detector 16 , a band-pass filter 17, a phase detector 18 can be performed using well-known technical solutions widely used in airborne radar systems (radars) for surveying the earth’s surface, used on aircraft [14].

Linear polarizer 3 is made in the form of a transition from a rectangular waveguide with horizontal linear intrinsic polarization to a circular waveguide [6, 7].

The rotator of the plane of polarization 4 is made in the form of a rotating section of a circular waveguide with a half-wave plate λ / 2 mounted inwardly [7] mechanically connected using a 1: 1 gear transmission with a synchronous step micromotor 9 of the DSh-0.025A type.

The angular position sensor 10 can be made in the form of a selsyn [14], the axis of which is connected via a gear to the rotor shaft of a synchronous step micromotor 9.

Tracking range meter 11 can be performed using well-known technical solutions widely used in radar systems (radar) automatic tracking of targets in range [10-13].

The block generating the reference signal with a double frequency of rotation of the plane of polarization 2Ω 14 can be performed according to the known scheme [6, 7].

Indicator 19 can be made in the form of a pointer device, the scale of which is calibrated in degrees of the angle of heel of the aircraft.

Compared with widely used instruments for measuring the roll angle of an aircraft, based on the use of gyroscopic orientation systems, the inventive polarization-modulation method for radar measuring the roll angle of an aircraft and a device for its implementation allow avoiding the constant accumulation of measurement errors over time. In addition, the use of radar reflectors with pronounced polarization-anisotropic properties as passive marker radar beacons when landing on non-equipped strips will reduce the cost of their maintenance, since passive beacons do not require power and routine maintenance of the equipment.

Information sources

1. Alexandrov A.S., Arno G.R. and others. The current state and development trends of foreign means and navigation systems of moving objects of military and civil purposes. - St. Petersburg, 1994 .-- 119 p.

2. Pelpor D.S., Yagodkin V.V. Gyroscopic systems. - M., Higher School, 1977 .-- 216 p.

3. Agadzhapov P.A., Vorobev V.G. et al. Automation of aircraft navigation and air traffic control. - M.: Transport, 1980 .-- 357 p.

4. Yarlykov M.S. Statistical theory of radio navigation. - M .: Radio and communications, 1985 .-- 344 p.

5. Kobak V.O. Radar reflectors. - M .: Sov.radio, 1975 .-- 248 p.

6. Kanareikin D. B., Potekhin V. A., Shishkin N. F. Marine polarimetry. - L .: Shipbuilding, 1963. - 328 p.

7. Kanareikin D. B., Pavlov N. F., Potekhin V. A. Polarization of radar signals. - M .: Soviet Radio, 1966 .-- 440 p.

8. Badulin NN, Gulko V.L., Masalov E.V. External calibration of radar polarimeters using passive reflectors. - Izv. Universities MB and MTR USSR Radioelectronics, Volume 29, No. 11, 1986. - p.81-82.

9. Azzam R., Bashar P. Ellipsometry and polarized light. - M .: Mir, 1981. - 588 p.

10. Dulevich V.E. Theoretical foundations of radar. - M .: Owls. Radio, 1978.- 608 p.

11. Kazarinov Yu.M. Radio engineering systems. - M .: Owls. Radio, 1968 .-- 406 p.

12. Pestryakov VB, Kuzenkov VD Radio engineering systems. - M .: Radio and communications, 1985 .-- 376 p.

13. Skolnik M. Handbook of radar. - M .: Owls. Radio, 1978, Vol. 4. - 376 p.

14. Davydov P.S. Aircraft radar systems. - M .: Transport, 1988 .-- 359 p.

Claims (2)

1. Polarization-modulation method of radar measurement of the roll angle of the aircraft when it is moving to a passive radar reflector of electromagnetic waves, characterized in that at a point with known coordinates have a passive polarization-anisotropic radar reflector of electromagnetic waves with a horizontal linear intrinsic polarization that coincides with the horizontal plane , passive polarization-anisotropic radar reflection is irradiated from the aircraft A linearly polarized electromagnetic wave, the plane of polarization of which rotates with frequency Ω, receives an electromagnetic wave reflected by a polarization-anisotropic radar reflector, the polarization of which coincides with the polarization of the radiated electromagnetic wave, from the received signal, in a linear orthogonal polarizing basis, single unit vectors which coincide with the transverse and vertical axes of the aircraft, horizontally linearly polarized ponent, determine the amplitude of the output signal of the receiver having a logarithmic amplitude characteristic and a linear detector,

,
where C is a constant taking into account the potential of the transmitter, the distance from the transmitter to the polarization-anisotropic radar reflector and vice versa, its effective scattering area (EPR) and the sensitivity of the receiver, the spectral component at a frequency of 2Ω is extracted from the output signal of the logarithmic receiver, its phase φ _{2Ω is measured} relative to the doubled angular position of the plane of polarization of the emitted electromagnetic wave and determine the angle of heel γ of the aircraft between the transverse axis of the aircraft parata and horizontal plane according to the formula

,
where φ _2Ω is the phase of the spectral component at a frequency of 2Ω (in radians),
+ γ is the positive angle of heel when the right wing of the aircraft or its transverse axis is below the horizontal plane,
-γ is the negative angle of heel when the right wing of the aircraft or its transverse axis is above the horizontal plane. 2. A device for measuring the roll angle of an aircraft, characterized in that at a point with known coordinates there is a polarization-anisotropic passive radar reflector of electromagnetic waves with horizontal linear intrinsic polarization, made in the form of a trihedral angular reflector, consisting of three planar mutually perpendicular metal or metallized triangular faces of the same size, significantly exceeding the wavelength λ = 3.2 cm, the opening of which is placed vertically A newly oriented polarization array made of round parallel metal rods (or wires) with a pitch of A = 5 mm and a diameter of B = 0.64 mm and sequentially connected synchronizer, transmitter, antenna switch, linear polarizer arranged on board an aircraft, made in the form of a transition from a rectangular waveguide on a circular waveguide, a polarization plane rotator with a frequency Ω made in the form of a section of a circular waveguide with a half-wave plate λ / 2 mounted in it and rotating with a frequency Ω ₁ = Ω / 2 and the antenna, while the circular waveguide section is mechanically connected using a gear 1: 1 gear with the rotor shaft of the synchronous step micromotor and the angular position sensor of the half-wave phase plate made in the form of a selsyn, the axis of which is mechanically connected using a gear with the rotor shaft of the synchronous stepper micromotor, while the control input of the synchronous stepper micromotor is connected to the output of the master oscillator, and the signal output of the angular position sensor is half-wave phase the plate is connected to the input of the balanced detector, and its output is connected to the input of the reference signal generating unit, the second output of the antenna switch is connected to a logarithmic receiver and a temporary selector made in the form of a controlled key, the synchronizer output is also connected to the first input of the tracking range meter, the output the time selector is simultaneously connected to the second input of the tracking range meter, to the input of the automatic gain control unit and to the follower about a connected peak detector and a band-pass filter, while the output of the tracking range meter is connected to the control input of the temporary selector, the output of the automatic gain control unit is connected to the control input of the logarithmic receiver, and the output of the band-pass filter is connected to the first input of the phase detector, and its second input is connected to the output of the reference signal generating unit, and the output of the phase detector is connected to the indicator input, the scale of which is calibrated in degrees of the roll angle of the aircraft and the central frequency of the bandpass filter and the frequency of the reference signal are equal to twice the frequency of rotation of the plane of polarization, and the intrinsic polarization of the linear polarizer is linear horizontal and coincides with the transverse axis of the aircraft.

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