RU2256194C2 - Mode of selection of a radar target with known polarized parameters and arrangement for its realization - Google Patents

Abstract

FIELD: the invention refers to radar and radio-navigation.

SUBSTANCE: it may be used for selection of radar targets at controlling air and sea transport at the background of interfering reflections and noise. The achieved technical result is in increasing of effectiveness of selection of a target with known polarized parameters that is to reduce to the minimum the possibility of adopting a decision about absence of the target at its presence( possibility of an admission of a target)at assigned possibility of a false alarm. The mode of selection is in that a radar target with known polarized parameters is irradiated by signals of linear polarization with a rotating plane of polarization. In the signal reflected from the target the second and the forth planes of polarization of the initial signal of harmonic are singled out and these parameters ( amplitudes and phases) are polarized parameters of the target. The decision about presence or absence of the selected target is taken on the basis of the decisive rule presenting a linear combination of polarized parameters with coefficients determined by statistical characteristics of polarized parameters at presence and at absence of the target. The threshold of adopting a decision of a decisive rule is determined by criteria of maximum credibility and is taken equal to a unit. The arrangement of selection of a radar target has a decisive block realizing the given decisive rule.

EFFECT: the invention increases effectiveness of selection of a radar target with known polarized parameters.

3 cl, 6 dwg

Description

The invention relates to radar and radio navigation and can be used for selection of radar targets when controlling the movement of air and sea transport against the background of interfering reflections and interference.

The purpose of the invention is to increase the efficiency of target selection with known polarization parameters.

A known method of measuring the polarization characteristics of a radar target and a device for its implementation: patent of the Russian Federation No. 1232034 A1, In.cl ⁴ G 01 S 13/02, priority from 30.03.1993. A method for measuring the polarization characteristics of a radar target consists in irradiating the target with a signal whose plane of polarization rotates with frequency Ω, receiving a signal reflected by the target, the polarization of which coincides with the polarization of the emitted signal, and also measuring the amplitude of the spectral component of the received signal at a frequency of 2Ω, characterized in that, in order to expand the functionality by measuring additional polarization parameters, the spectral component is extracted from the received signal at a frequency of 4Ω, measure the amplitude of the spectral component of the received signal at a frequency of 4Ω, and also measure the phase of the spectral components at frequencies 2Ω and 4Ω relative to the doubled and quadrupled angular position of the plane of polarization of the emitted signal, respectively, followed by measurement of polarization parameters by the formulas:

electrical form factor ρ = 2 · A _2Ω ;

phase shift introduced by the target Δ φ = (2 · A _4Ω ) ^0.42 ;

orientation angle of the polarization basis of the target at

orientation angle of the polarization basis of the target at

where A _2Ω is the amplitude of the spectral component at a frequency of 2Ω (in decibels);

where A _4Ω is the amplitude of the spectral component at a frequency of 4Ω (in decibels);

where φ _2Ω is the phase of the spectral component at a frequency of 2Ω (in radians);

where φ _4Ω is the phase of the spectral component at a frequency of 4Ω (in radians).

A device for measuring the polarization characteristics of radar targets includes a series-connected transmitter, an antenna switch, a rotating section of a circular waveguide with an integrated phase plate and an antenna, as well as a control unit, a series-connected receiver, a gating unit and a peak detector, the receiver input being connected to the second output of the antenna switch , an actuator, the first output of which is mechanically coupled to a rotating circular wave section The ode, the output of the control unit is connected to the input of the actuator, and the second input of the gating unit is connected to the second output of the transmitter, characterized in that a first band-pass filter tuned to a quadruple frequency of rotation of the phase plate is inserted into it, a second band-pass filter tuned to an accelerated speed phase plate, two phase, two amplitude detectors, four indicators and a sensor for the angular position of the phase plate, and the inputs of the first and second bandpass filters are connected to the output an infrared detector, the input of the first amplitude detector and the first input of the first phase detector are connected to the output of the first bandpass filter, the input of the second amplitude detector and the first input of the second phase detector are connected to the output of the second bandpass filter, the input of the angular position sensor of the phase plate is mechanically connected to the second output of the actuator , the second inputs of the first and second phase detectors are connected to the first and second outputs of the angular position sensor of the phase plate, respectively, The odes of the first and second amplitude and first and second phase detectors are connected to the inputs of the first, second, third, and fourth indicators, respectively, while the receiver is made logarithmic, and the electric length of the phase plate is half the wavelength generated by the transmitter.

Analysis of the proposed method showed that this method does not allow the selection of radar targets, and is intended only for measuring the polarization characteristics of radar targets. The disadvantages of the proposed device, which measures the polarization characteristics of radar targets, is that this device does not have a unit that makes decisions about the presence or absence of a selectable target based on the totality of polarization characteristics in accordance with the optimal decision rule.

In [2], the problem of selecting radar targets according to polarization features was formulated in terms of testing statistical hypotheses and an intuitively justified decision rule was proposed that allows one to attribute the observed radar target to one of two mutually exclusive classes, however, there is no study of the optimality of this decision rule.

In this application, a synthesis of such a decision-making rule for selecting a target according to the set of polarization features is carried out, which would be optimal by the criterion of maximum likelihood [3].

The polarization parameters of a target belonging to one of k mutually exclusive classes are random variables characterized by some multidimensional conditional probability density distribution function:

where x ₁ , ..., x _n or X _n are the polarization parameters of the kth target s _k , from the group of goals the total number of which is K.

The presence of the sign of the conditional probability density is emphasized by the fact that, in the general case, each of the goals is characterized by its probability density distribution function, both in form and in the value of the parameters of the distribution function.

In the process of measuring the signal reflected from the target, the polarization parameters of the target are extracted from it, as a result of which a combination of these parameters is formed. Those. a signal means a certain function, depending on time, having a complex shape and having a complex spectral composition of harmonic components. At each moment of time, all these harmonic components are present in the signal, and it is they that are considered as the polarization characteristics of the radar target. Thus, by measuring the signal reflected from the target, we mean the allocation of harmonic components from this signal that carry information about the polarization characteristics of the radar target. This information is considered as a set of polarization parameters.

The decisive rule allows you to attribute the resulting set of polarization parameters to one of the mutually exclusive classes, each of which corresponds to a particular purpose.

The decision is made on the basis of the theory of statistical decisions [3].

Decisive rules for K≥2 classes are based on a comparison of likelihood relationships:

among themselves or with a certain threshold [4]. In detection problems (two-way recognition) K = 2, the likelihood ratio takes the form:

and the decision is made by comparing the likelihood ratio with the threshold λ. For 1 (X _n ) ≥ λ, a decision is made on whether the set of polarization parameters of the target belongs to the class s ₂ , for 1 (X _n ) ≤ λ, the set is assigned to class s ₁ .

In multi-alternative problems with the number of classes K> 2, the decision rule will have a more complex form [4].

To calculate the characteristics of detecting radar targets by polarization signs, we use the maximum likelihood criterion [3].

For two-alternative recognition, the decision rule for the maximum likelihood criterion is:

We assume that s ₂ corresponds to the detected target, as ₁ corresponds to interference, i.e. lack of purpose; or corresponds to a goal that does not interest us, i.e. purpose, for which we have no task of detecting it.

The threshold λ in the case of using the maximum likelihood criterion takes a value equal to unity (λ = 1) [3].

It is known [3] that for a priori known densities w (X _n | s ₁ ) and w (X _n | s ₂ ), rule (4) ensures the adoption of the most plausible decision on the presence or absence of a target in comparison with any other rules in if there is no a priori information about the probability of the occurrence of the target, or about the losses incurred in the event of a wrong decision. In this sense, rule (4) is optimal.

To assess the polarization parameters of a radar target, for example, modulation methods based on the use of polarization-modulated probing signals can be used [1, 5, 6].

In this case, linearly polarized sounding signals are modulated by rotating their plane of polarization with a frequency of Ω — the frequency of polarization modulation.

As a result of spectral analysis of the signal at the output of the receiver with a logarithmic amplitude characteristic, in the presence of a polarization modulator in the high-frequency path of the locator, it was revealed [7, 8] that the amplitudes and phases of the spectral components of the envelope of the received signal at frequencies that are multiples of the frequency of polarization modulation carry information about polarized target parameters. The most informative are the second and fourth harmonics of the frequency of polarization modulation. Moreover, being distracted from the physical nature of the polarization parameters, in the problem of selecting radar targets, the amplitudes and phases of the spectral components themselves can be considered the polarization parameters of the target.

In this formulation of the problem, the multidimensional conditional distribution function of the probability density of the polarization parameters of the target has a dimension of 4 and represents the joint distribution of the following polarization parameters of the target:

A _2Ω is the amplitude of the second harmonic of the received signal;

And _4Ω is the amplitude of the fourth harmonic of the received signal;

φ _2Ω - phase of the second harmonic of the received signal;

φ _4Ω is the phase of the fourth harmonic of the received signal.

Consider the case of two-alternative recognition, when it is necessary to decide on the presence or absence of a target with previously known polarization characteristics (i.e., with known probability density distribution functions w (A _2Ω , A _4Ω , φ _2Ω ; φ _4Ω | s ₁ ) and w ( A _2Ω , A _4Ω , φ _2Ω , φ _4Ω | s ₂ )) one set of values of the polarization parameters.

The prominence of the polarization characteristics means that they are known as the form of the probability density functions w (A _2Ω , A _4Ω , φ _2Ω , φ _4Ω | s ₁ ) and w (A _2Ω , A _4Ω , φ _2Ω , φ _4Ω | s ₂ ), so and the characteristics (in particular, mean values and standard deviations of the parameters A _2Ω , A _4Ω , φ _2Ω , φ _4Ω ) of these functions. Those. it is assumed that the probability density functions w (A _2Ω , A _4Ω , φ _2Ω , φ _4Ω | s ₁ ) and w (A _2Ω , A _4Ω , φ _2Ω , φ _4Ω | s ₂ ) together with their characteristics are measured previously, for example, using the methods described in [1, 2, 6, 7, 8].

We assume that the polarization parameters of both class s ₁ and class s ₂ are collections of statistically independent random variables subject to the normal distribution law.

To begin with, consider the one-dimensional case, i.e. Let’s try to select the target by the value of only one parameter (no matter what, let it be A _2Ω ) in accordance with the maximum likelihood criterion.

In the case of the normal distribution law, the probability density functions are described by the relations [3]:

и

^- средние значения параметра А_2Ω для классов s₁ и s₂, соответственно;

и

^- среднеквадратичные отклонения параметра А_2Ω для классов s₁ и s₂, соответственно. Величины

,

,

и

предполагаются известными и определяются конкретными классами s₁ и s₂.

and

^- average values of parameter A _2Ω for classes s ₁ and s ₂ , respectively;

and

^- standard deviations of the parameter A _2Ω for classes s ₁ and s ₂ , respectively. Quantities

,

,

and

are assumed to be known and determined by the specific classes s ₁ and s ₂ .

We determine the likelihood ratio for these two probability density functions:

After calculating the value of this function, it must be compared with the threshold λ = 1.

If the value of 1 (A _2Ω ) is greater than or equal to λ, then a decision is made that the given value of A _2Ω corresponds to the goal of class s ₂ and the goal of class s ₁ otherwise.

A graphic illustration of this process is shown in figure 1.

Obviously, in the case of equality of the standard deviations of the parameter A _2Ω for classes s ₁ and s ₂ , the threshold value λ = 1 corresponds to a single value of the polarization parameter A _{2Ω pores} , since the likelihood ratio seems to be a monotonic exponential function in this case.

Therefore, for systems in which the threshold will not change during operation, it is possible not to calculate the value of the likelihood ratio function 1 (A _2Ω ) each time, but, having previously determined A _{2Ω pores} , compare with it the value of the polarization parameter A _{2Ω itself} .

принимается решение о наличии цели s₂ и s₁ - в противном случае.Moreover, if

a decision is made on whether s ₂ and s ₁ exist — otherwise.

In Fig. 1, the area of the hatched region P1 gives the probability of detecting the target, P2 the probability of missing the target, and P3 the probability of false alarm, i.e. situations when the goal is absent, and the system decides on its availability.

In accordance with the maximum likelihood criterion, this algorithm for target selection by one polarization parameter is optimal.

Consider a situation where target detection is carried out using two polarization parameters (for example, A _2Ω and φ _2Ω ). At the same time, we will try to determine whether it will be sufficient to compare the values of these parameters with the thresholds defined for each of these parameters separately in order to decide on whether the sample belongs to any class. Those. we will try to determine whether the fulfillment of condition (4) for the parameter A _2Ω and a similar condition for the parameter φ _{2Ω will be sufficient} ; in order to decide that the sample belongs to the class s ₂ .

Since we assume the normal distribution law, the probability density functions for the polarization parameter φ _{2Ω of the} target of classes s ₁ and s ₂ will be equal, respectively:

Where:

и

^- средние значения параметра φ _2Ω для классов s₁ и s₂, соответственно;

и

- среднеквадратичные отклонения параметра φ _2Ω для классов s₁ и s₂, соответственно. Величины

,

,

и

предполагаются известными и определяются конкретными классами s₁ и s₂.

and

^- average values of the parameter φ _2Ω for classes s ₁ and s ₂ , respectively;

and

- standard deviations of the parameter φ _2Ω for classes s ₁ and s ₂ , respectively. Quantities

,

,

and

are assumed to be known and determined by the specific classes s ₁ and s ₂ .

In addition, since we assume the statistical independence of the polarization parameters A _2Ω and φ _2Ω , their combined two-dimensional distribution density function will be equal to the product of one-dimensional for each of these parameters:

Consider the situation when the standard deviations of the parameters φ _2Ω and A _2Ω for both groups s ₁ and s ₂ are equal to each other:

The likelihood ratio for two-dimensional probability density functions of the polarization parameters φ _2Ω and A _{2Ω of the} goals of groups s ₁ and s ₂ in this case will be equal to:

Having done the necessary transformations and introducing the notation:

we finally get:

As in the case of the one-dimensional likelihood ratio, after calculating the value of this two-dimensional function, it must be compared with the threshold λ = 1.

If the value 1 (A _2Ω , φ _2Ω ) is greater than or equal to λ, then the decision is made that this combination of the values of the polarization parameters A _2Ω and φ _2Ω corresponds to the goal of class s ₂ and the goal of class s ₁ otherwise.

A graphic illustration of this process is shown in figure 2.

Thus, the likelihood ratio is a curved plane whose curvature is described by an exponential law (16).

The threshold λ also represents a plane parallel to the plane (A _2Ω 0 φ _2Ω ). Since the projection of the curved plane 1 (A _2Ω , φ _2Ω ) onto the plane (a _2Ω 0 φ _2Ω ) is linear, the intersection of the λ plane with the plane 1 (A _2Ω , φ _2Ω ) gives the projection onto the plane (A _2Ω 0 φ _2Ω ) straight line described by the ratio:

As in the case of using only one parameter to solve the target detection problem, due to the monotonicity of function 1 (A _2Ω , φ _2Ω ) in any of the coordinates, for any fixed value of another coordinate, the calculation of the likelihood ratio for a given set of polarization parameters (A _2Ω , φ _2Ω ) can be replaced using the simpler relation (17).

Thus, assuming λ = 1, we uniquely determine the line (17), i.e. we uniquely determine the rule for making decisions on whether a goal belongs to a particular class:

Thus, it turns out that in order to make a decision on whether a given population meets one of the two classes of targets for two polarization parameters, it is not enough to compare the values of these parameters with the threshold levels determined for each of these parameters separately, as suggested in [2]. It is necessary to use relation (18), which gives the optimal decision-making rule.

If the polarization parameters are compared separately with the thresholds determined for them, and the decision on whether the target belongs to class s ₂ is made only if both parameters exceed this threshold, the probability of a wrong decision on whether the target belongs to class s ₁ increases compared to the probability of a wrong decision, defined by the optimal rule (18).

Let us explain this situation graphically. To do this, we depict the projection of the graphs of _figure 2 on the plane (A _2Ω 0 φ _2Ω ) (figure 3, a and b).

In Fig. 3, the region S1 corresponds to the projection of the figure w (A _2Ω , φ _2Ω | s ₂ ), cut off by the planes φ _{2Ω pores} and A _{2Ω pores} - figure 3, a, and the plane a · A _2Ω + b · φ _2Ω + с = ln (λ) - figure 3, b, the volume of which is equal to the probability of target detection s ₂ .

Region S2 corresponds to the projection of the figure w (A _2Ω , φ _2Ω | s ₂ ), cut off by the planes φ _{2Ω pores} and A _{2Ω pores} - figure 3, a, and the plane a · A _2φ + b · φ _2Ω + с = ln (λ ) - figure 3, b, the volume of which is equal to the probability of missing the target.

Region S3 corresponds to the projection of the figure, w (A _2Ω , φ _2Ω | s ₁ ), cut off by the planes φ _{2Ω pores} and A _{2Ω pores} - figure 3, a, and the plane a · A _2Ω + b · φ _2Ω + с = ln ( λ) - figure 3, b, the volume of which is equal to the probability of false alarm.

From the point of view of the maximum likelihood criterion used by us, with equal volumes of figures corresponding to region S3, as can be clearly seen from figure 3, when using criterion (18), the probability of missing the target will be less.

Generalizing this approach to the case of using all four polarization parameters and introducing additional notation:

Where:

и

- средние значения параметра А_4Ω для классов s₁ и s₂, соответственно;

и

^- среднеквадратичные отклонения параметра А_4Ω для классов s₁ и s₂, соответственно, причем:

and

- average values of parameter A _4Ω for classes s ₁ and s ₂ , respectively;

and

^- standard deviations of the parameter A _4Ω for classes s ₁ and s ₂ , respectively, moreover:

и

- средние значения параметра φ _4Ω для классов S₁ и S₂, соответственно;

и

^- среднеквадратичные отклонения параметра φ _4Ω для классов S₁ и S₂, соответственно, причем:

and

- average values of the parameter φ _4Ω for classes S ₁ and S ₂ , respectively;

and

^- standard deviations of the parameter φ _4Ω for classes S ₁ and S ₂ , respectively, and:

we get:

_,

_,

,

,

и

предполагаются известными и определяются конкретными классами s₁ и s₂.Quantities

_,

_,

,

,

and

are assumed to be known and determined by the specific classes s ₁ and s ₂ .

Whence we get that the likelihood ratio for the four-dimensional probability density functions of the polarization parameters (A _2Ω , A _4Ω , φ _2Ω , φ _4Ω ) of the goals of groups s ₁ and s ₂ in this case will be equal to:

As for the decision rule, it will be as follows:

For the convenience of practical implementation, the decision rule on the presence of a selectable target s ₂ can be written as follows:

A selectable target is present if:

for λ = 1.

Figure 4 shows the structural electrical diagram of the proposed device that implements the rule (26); figure 5 is an example of a polarization modulator; Fig.6 is an example of the execution of the gating unit.

The radar target selection device comprises a transmitter 1, an antenna switch 2, a polarization modulator 3, an antenna 4, a gating unit 5, a receiver 6, a first and second phase shifters 7, 8, a peak detector 9, a first and second bandpass filters 10, 11, a first amplitude detector 12, a first phase detector 13, a second amplitude detector 14, a second phase detector 15, an indicator 16, and a decision unit 17 that includes first, second, third, and fourth proportional multipliers 18-21, an adder 22, and a comparator 23. A polarization modulator 3 INH waveguide rotating section 24, an actuator 25, the control unit 26 and the sensor 27 of the angular position. The gating unit 5 comprises a delay unit 28 and a key 29.

A device for selecting a radar target works as follows.

The transmitter 1 generates high-frequency pulses, which are fed through the antenna switch 2 to the polarization modulator 3. The purpose of the polarization modulator 3 is to convert the linearly polarized radiation of the transmitter 1 into radiation, the plane of polarization of which rotates with frequency Ω. In addition, the purpose of the polarization modulator 3 is to isolate from the signal reflected by the target a component whose plane of polarization coincides with the plane of polarization of the emitted pulse. The polarization modulator 3 is made in the form of a circular waveguide section 24 rotating with a frequency Ω / 2, with a half-wave phase plate mounted in it (not shown in FIG. 5). The rotary section 24 is connected to the antenna switch 2 by a transition from a circular to a rectangular waveguide (not shown in FIG. 5). The rotation of the rotating section 24 is provided by an actuator 24 controlled by the signals of the control unit 26. To obtain information about the angular position of the phase plate, the polarization modulator 3 includes an angular position sensor 27 mechanically coupled to the actuator 25. Sinusoidal voltages of 2Ω and 4Ω are generated at the two outputs of the angular position sensor 27. The outputs of the sensor 27 of the angular position are the first and second reference outputs of the polarization modulator 3.

After passing the polarization modulator 3, the signal enters the antenna 4 and is emitted in the direction of the target. The signal reflected by the target is captured by antenna 4 and, having passed the polarization modulator 3 and antenna switch 2, is fed to the input of receiver 6. At receiver 6, the signal is amplified to the required level and fed to the input of gating unit 5. The start pulse of the transmitter 1 is received at the control input of the gating unit 5 from the transmitter 1. In the gating unit 5, the start pulse of the transmitter 1 is delayed by the delay unit 28 for a time equal to the signal propagation time to the target and back, after which it is supplied to the control input of the key 29 through which the received signal passes. From the output of the gating unit 5, the received signal is fed to the input of the peak detector 9, where the level of 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 9, the signal is supplied to the inputs of the first and second bandpass filters 10, 11, the first of which is tuned to a frequency of 2Ω, and the second to 4Ω. The purpose of the first and second bandpass filters 10, 11 is the selection of the spectral components from the received signal at frequencies of 2Ω and 4Ω.

From the outputs of the first and second bandpass filters 10, 11, sinusoidal signals with a frequency of 2Ω and 4Ω are fed to the inputs of the first and second amplitude and phase detectors 12-15. The reference voltage for the first and second phase detectors 13, 15 are sinusoidal voltages removed from the first and second reference outputs of the polarization modulator 3, passed through the first and second phase shifters 7, 8. The magnitude of the phase delay in these phase shifters 7, 8 is set equal to twice and quadruple orientation of the target’s own coordinate system, the selection of which is carried out. So, for example, to select a target for which the orientation of its own coordinate system coincides with the orientation of the coordinate system associated with antenna 4, the phase delay in the first and second phase shifters 7 and 8 is zero.

From the outputs of the first and second amplitude and phase detectors 12-15, constant voltages proportional to the amplitudes and phases of the spectral components of the received signal at frequencies of 2Ω and 4Ω are applied to the inputs of four proportional multipliers 18-21. These multipliers 18-21 carry out a proportional multiplication of the voltages from the outputs of the first and second amplitude and phase detectors 12-15, by the value of the corresponding coefficient. So, the voltage from the output of the amplitude detector 12 is multiplied by a proportional amplifier 20 times, the voltage from the output of the phase detector 13 is multiplied by the proportional amplifier 18 by a factor of b, the voltage from the output of the amplitude detector 14 is multiplied by a factor of 21 by d times, the voltage from the output of the phase detector 15 multiplied by a proportional amplifier 19 times. The voltages from the outputs of the proportional multipliers 18-21 are supplied to the four inputs of the adder 22. The voltage U ₂ proportional to parameter c is supplied to the fifth input of the adder. The adder 22 sums the incoming voltage at its four inputs from the outputs of the four proportional multipliers 18-21 and voltage U ₂ . The total voltage from the output of the adder 22 is fed to the input of the comparator 23. At the reference input of the comparator 23, a threshold voltage U ₁ is proportional to the threshold for decision-making of rule (26) - ln (λ). The value of the threshold voltage U ₂ proportional to the decision threshold of rule (26) -ln (λ), the multiplication factors of the proportional multipliers 18-19 a, b, d and e, as well as the value of the voltage U ₂ proportional to parameter c, are calculated in advance based on from the polarization properties of breeding targets, their statistical characteristics, as well as the analytical relationship of the amplitudes and phases of the spectral components with the polarization parameters of the target.

The comparator 23 operates in such a way that the voltage at its output appears only when the voltage at the signal input is equal to or greater than the reference voltage. The indicator 16 captures the presence of the output signal of the deciding unit 17 and, accordingly, the presence of a selectable target. As an indicator 16, a pointer device, a recorder, an electron beam indicator, etc. can be used.

Indicator 16 fixes the presence of target s2 only if the condition of decision rule (26) is satisfied, or, equivalently, if the voltage from the output of adder 22 exceeds the threshold voltage U ₁ .

Using the proposed device can improve the efficiency of selection of radar targets and select anisotropic targets on an anisotropic background.

LIST OF USED LITERATURE

1. Copyright certificate of the USSR. No. 1232034 A1, In.cl ⁴ G 01 S 13/02, priority 03.30.1993

2. Badulin N.N. Detection of artificial radar targets by polarization features against the background of the earth's surface / NN Badulin, VV Bylina, V.L. Gulko, A.F. Petrov, K.G.Sokolov, E.L. Shoshin. - Izv. universities of the USSR, Radioelectronics. - 1991. - No. 8. - p. 29-32.

3. Levin B.R. Theoretical foundations of statistical radio engineering. Prince 1-3 / B.R. Levin. - M .: Owls. Radio, 1974-1976. book 1 - 552 s., book 2 - 392 s., book 3 - 288 s.

4. Fomin Ya.A. Statistical theory of pattern recognition / Ya.A. Fomin, G.R.Tarlovsky. - M .: Radio and communications, 1986. - 264 p.

5. Bogorodsky VV Polarization of the scattered and intrinsic radio emission of the earth cover / V.V. Bogorodsky, D. B. Kanareykin, A. I. Kozlov. - L .: Gidrometeoizdat, 1981. - 297 p.

6. Badulin N.N. Remote sensing of the microphysical structure of clouds using polarization manipulation / NN Badulin, A.P. Batsula, E.B. Kulsheneva, S.P. Lukyanov, E.V. Masalov, V.N. Tatarinov. - Izv. universities of the USSR, Physics. - 1983, No. 6.

7. Badulin N.N. Spectral characteristics of echo signals during polarization modulation of radar radiation / N.N. Badulin, V.L. Gulko. - Izv. universities of the USSR, Radioelectronics. - 1988. - No. 4. - p. 74-76.

8. Badulin N.N. The spectral characteristics of signals scattered by radar targets during polarization modulation of radar radiation / NN Badulin, V.L. Gulko, E.V. Maslov. - Izv. universities of the USSR, Radioelectronics. - 1991. - No. 11. - p. 65-67.

Claims (2)

1. A method for selecting a radar target with known polarization parameters, based on irradiating the target with linear polarization radar signals with a plane of polarization rotating at a frequency Ω, receiving a signal reflected from the target, extracting the second amplitude A _2Ω relative to the harmonic frequency Ω of the received signal, the fourth amplitude A _4Ω frequency Ω of the harmonic of the received signal, phase φ _2Ω second relative to the frequency Ω of the harmonic of the received signal, phase φ _4Ω fourth relative to the frequency Ω of the harmonic the received signal, followed by a decision on the presence or absence of a selectable target according to the values of the polarization parameters A _2Ω , A _4Ω , φ _2Ω , φ _4Ω , characterized in that the decision is made according to the rule: if the condition is met: (a · A _2Ω + b · φ _2Ω + d · A _4Ω + e · φ _4Ω + c ′) ≥0, then the selectable target is present, and is absent, if this condition is not met, Where

Where

and

^- average values of the parameter A _2Ω for the absence and presence of a selectable target, respectively;

- standard deviation of the parameter A _2Ω ;

and

^- average values of the parameter φ _2Ω for the absence and presence of a selectable target, respectively;

- standard deviation of the parameter φ _2Ω ;

and

- average values of the parameter A _4Ω for the absence and presence of a selectable target, respectively;

standard deviation of parameter A _4Ω ;

and

- average values of the parameter φ _4Ω for the absence and presence of a selectable target, respectively;

standard deviation of the parameter φ _4Ω . 2. A device for selecting radar targets, comprising an indicator, first and second phase detectors, first and second amplitude detectors, a serially connected transmitter, an antenna switch, a polarization modulator and an antenna and serially connected receiver, a gating unit and a peak detector, the output of which is connected to the inputs of the first and a second band-pass filter, while the control input of the gating unit from the transmitter receives a trigger pulse, the second output of the antenna switch is connected to the input m of the receiver, the output of the first bandpass filter is connected to the first input of the first phase detector and the input of the first amplitude detector, the output of the second bandpass filter is connected to the first input of the second phase detector and the input of the second amplitude detector, while the first reference output of the polarization modulator is connected to the second input of the first phase detector through the first phase shifter, the second reference output of the polarization modulator is connected to the second input of the second phase detector through the second phase shifter, output The odes of the first and second phase detectors and the first and second amplitude detectors are connected respectively to the first, second, third and fourth inputs of the decision block, the output of which is connected to the indicator input, characterized in that the decision block contains the first, second, third and fourth proportional multipliers, the outputs of which are connected to the corresponding inputs of the adder, and an additional signal is supplied to the fifth input of the adder, the output of the adder is connected to the input of the comparator, while the first, second, third and fourth odes and output deciding unit are respectively proportional to the inputs of like multipliers and an output of the comparator.

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