RU2274874C1 - Method of measurement of angular coordinate of object and radar station for realization - Google Patents

Abstract

FIELD: radio location.

SUBSTANCE: method can be used for measurement of angular coordinates of objects in radar stations with phased array. The method and device for measurement of angular coordinates of object include irradiation of probing signals, reception of reflected signals for at least two positions of array beam swung in amplitude, measurement of amplitude of received signals corresponding to those positions of beam, calculation of angular coordinate of object. Deviation of beam from normal line of array is determined additionally at any angular position of beam and width of beam is determined on the base of deviation value. Then angular coordinate of object is found.

EFFECT: improved precision of measurement.

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Description

The proposed technical solutions relate to the field of radar and can be used to measure the angular coordinates of objects in radar stations (radar) with a phased antenna array (PAR).

A known method for measuring the angular coordinate of an object is a method that includes emitting sounding signals, receiving reflected signals, comparing the amplitudes of the received signals with a threshold, calculating the angular coordinate of the object (Theoretical Basics of Radar. Edited by Y.D.Shirman. M., Sov. Radio, 1970, p. 284). The angular coordinate of the object is calculated in this case as the arithmetic average of the angular positions of the beam at the beginning and at the end of the packet. By a burst is meant a set of signals detected in successive positions of the beam by the measured angular coordinate (ibid.).

A known device for measuring the angular coordinate of an object (θ ₀ ) is a radar station containing (Fig. 1) a serially connected control device, a transmitter, an antenna switch, a receiver, a threshold device, a storage device, a computing device, as well as an antenna, input / output which is connected to the input / output of the antenna switch, the beam control device, the input of which is connected to the second output of the control device, the first output to the control input of the antenna, the second output to the second input second device, the third output control device connected to the second input computing devices. (Theoretical Foundations of Radar. Edited by V.E.Dulevich. M., Sov. Radio, 1978, p. 19, Fig. 1.5a).

In the known method and device, the signal magnitude is determined by comparing it with one fixed detection threshold. Therefore, the position of the object relative to the antenna pattern is determined very roughly, i.e. the accuracy of measuring the angular coordinate of the object is small. Thus, a disadvantage of the known technical solutions is the low accuracy of measuring the angular coordinate.

The closest way to measure the angular coordinate of an object (θ ₀ ) is the method (Theoretical Foundations of Radar. Edited by Ya.D.Shirman, M., Sovetskoe Radio, 1970, pp. 296-298), including the radiation of sounding signals, the reception of reflected signals at least in two positions of the antenna beam (θ _i , θ _j ) spaced along the angular coordinate (i ≠ j), measuring the amplitudes of the received signals (U _i , U _j ) corresponding to these beam positions, calculating the angular coordinate of the object by solving the equation :

where F _i (θ ₀ , θ _i , Δ) and F _j (θ ₀ , θ _j , Δ) are functions that describe the antenna pattern at the i-th and 7-th beam positions, respectively;

Δ is the beam width of the antenna at half power relative to the maximum of the beam.

The method uses an antenna in which the beam width does not depend on its angular position.

Closest to the claimed device is a radar (figure 2), containing serially connected control device 1, transmitter 2, antenna switch 3, receiver 4, memory 5, computer 6, as well as antenna 7, the input / output of which is connected with the input / output of the antenna switch 3, the beam control device 8, the input of which is connected to the second output of the control device 1, the first output to the control input of the antenna 7, the second output to the second input of the storage device 5, the third output of the device Control TBA 1 is connected to the second input computing devices 6 (Theoretical bases radar. Ed. Ya.D.Shirmana. M, Sov. radio, 1970, str.221, Figure 5.4).

The work closest to the claimed radar when measuring the angular coordinate of the object is as follows. At the command of the control device 1, a command is issued from the beam control device 8, according to which the antenna is mechanically mounted in a position that provides the radiation of the probing signal in the required (kth) direction of the radar field of view (k is the number of the angular position of the beam when viewing the field of view, k = 1,2, ..., i, j, ...). The angular coordinate of the beam θ _{k is} stored in the storage device 5. In the transmitter 2, a probing signal is generated, which through the antenna switch 3 enters the antenna 7 and is emitted. The signal reflected from the object is received by the antenna 7 and fed through the antenna switch 3 to the receiver 4. The amplitude of the received signal U _{k is} stored in the memory 5. By the command of the control device 1, the next direction of the field of view is selected for the radiation of the probe signal and the operations are repeated. Thus, during the inspection of the field of view in the storage device 5, the amplitudes of the signals reflected from the object are recorded together with the corresponding beam coordinates. In the computing device 6 from two directions of the beam, two adjacent directions (θ _i , θ _j ) with the largest amplitudes of the reflected signals are selected and, in accordance with formula (1), the angular coordinate of the object is calculated.

It is known that in a flat headlamp with a deviation from the normal, the beam expands (Radar Reference. Ed. M. Skolnik. M., Sov. Radio, 1977, v.2, p.133). In addition, in a radar with a PAR, as a rule, a program review is used, in which the beam width in certain parts of the zone is intentionally (hereinafter referred to as "program"). Thus, in radar with PAR, the beam width is variable. In the closest technical solutions, the beam is moved by the mechanical movement of the antenna; therefore, the beam width Δ does not depend on the angular position of the beam. In this regard, in a radar with a PAR, the closest method leads to a deterioration in the accuracy of measuring the angular coordinate of the object.

Thus, a drawback of the closest technical solutions is the low accuracy of measuring the angular coordinate of the object.

The solved problem (technical result) is to increase the accuracy of measuring the angular coordinate of the object.

The problem is solved in that in the method of measuring the angular coordinate of the object, including the radiation of the probing signals, receiving reflected signals at least two positions of the antenna beam spaced along the angular coordinate, measuring the amplitudes of the received signals corresponding to these positions of the beam, calculating the angular coordinate of the object, according to the invention, at each angular position of the beam, the deviation of the beam from the normal of the antenna is additionally determined and based on this, its width is determined, after which the angles are calculated th coordinate of the object.

The problem is also solved by the fact that the angular coordinate is calculated in accordance with the formulas:

,

,

where θ ₀ is the measured angular coordinate of the object;

θ _i , θ _j are the angular coordinates of the beam at the ith and jth (i ≠ j) positions, respectively;

U _i , U _j are the amplitudes of the received signal at the i-th and j-th beam positions, respectively;

Δ _i = Δ _n / cos (θ _iе ) + Δ _in , Δ _j = Δ _n / cos (θ _jе ) + Δ _jn are the beam widths at the ith and jth positions, respectively;

θ _ie , θ _je is the measured deviation of the beam from the normal of the antenna during electronic scanning at the ith and jth positions, respectively;

Δ _in , Δ _jn is the programmed change in the beam width at the ith and jth positions, respectively;

Δ _n is the beam width at its position on the antenna normal.

The problem is also solved by the fact that in a radar station containing a serially connected control device, a transmitter, an antenna switch, a receiver, a storage device, a computer, as well as an antenna, the input / output of which is connected to the input / output of the antenna switch, a control device beam, the input of which is connected to the second output of the control device, the first output to the control input of the antenna, the second output to the second input of the storage device, the third output of the devices control is connected to the second input computing devices, according to the invention introduced a device for determining the beam width, the first and second inputs connected respectively to the second and third outputs of beam steering unit, and an output connected to a third input of the memory device.

Let us explain the essence of the proposed technical solution.

In antennas without electronic scanning, as already noted, the angular position of the beam is completely determined by the position of the antenna. In this case, the beam width does not depend on the angular position of the beam.

In a flat headlamp with electronic scanning, the angular position of the beam θ _k is determined by the angular position of the normal of the _headlamp θ _kn , which is established by mechanical movement of the headlamp, and the deviation of the beam from the normal of the antenna due to electronic scanning θ _ke .

It is known that in a flat headlamp, when the beam deviates from the normal of the antenna, the beam expands. So, if the beam width at its position on the normal is Δ _n , then when the angle θ _ke deviates from the normal, the beam width is determined in accordance with the formula (Radar Reference. Ed. M. Skolnik. M., Sov. Radio, 1977, t.2, p.133).

In addition, in a radar with a programmatic view, to ensure the required viewing area, the beam width is intentionally (programmatically) changed. In this case, an additional (program) increment of the beam width Δ _kn appears and the beam width is equal to:

Thus, in a radar with a PAR, the beam width for any two beam positions that differ in the angular coordinate (k = i and k = j) is usually different. In this case, the equal-signal direction of the antenna system (in a monopulse radar) or the equal-signal direction at two angular positions of the beam (in a single-channel radar) is shifted from the middle of the angular distance between these positions of the beam.

In the inventions, the indicated offset of the equal-signal direction is taken into account, and thereby the accuracy of measuring the angular coordinate is increased. For this, for each pair of measurements of the signal amplitude (i-th and j-th), the beam deviation from the antenna normal (θ _iе , θ _jе ) is _determined and taking into account the programmed change in the beam width (Δ _in , Δ _jn ) in accordance with the formula ( 4) the values of the beam width Δ _i , Δ _{j are} determined (assuming k = i and k = j). After that, the angular coordinate of the object θ _{0 is} calculated.

The angular coordinate of the object θ ₀ in the general case is calculated by solving the equation:

which follows from (1) by replacing the functions describing the antenna pattern in two beam positions F _i (θ ₀ , θ _i , Δ) and F _j (θ ₀ , θ _j , Δ) with the same width Δ, by function F _i (θ ₀ , θ _i , Δ _i ) and F _j (θ ₀ , θ _j , Δ _j ) describing the radiation pattern of the antenna in two beam positions with different Δ _i and Δ _j .

Methods for solving equations of the form (5) are known (Theoretical Foundations of Radar. Edited by Ya.D.Shirman. M., Sov. Radio, 1970, pp. 276-282). However, the determination of the angular coordinate in accordance with them requires significant computational and time resources, which in some cases, for example, in mobile radars, may be absent. Therefore, the invention proposed another option that does not require significant computational and time resources - in accordance with formulas (2). It is based on the well-known fact that the radiation patterns normalized to their maximum value in almost all real species in the region of the main beam (if the amplitude distribution of the field that decreases to the edges of the aperture of the antenna, which usually takes place) are described with high accuracy by a Gaussian curve (Rakov V. I. Indicator devices of radar stations. L. Sudpromgiz, 1962, p.24-29):

If reflected signals from more than two positions of the antenna beam are used, then to obtain an unambiguous measurement when calculating in (2), two adjacent beam positions (θ _i , θ _j ) with the largest amplitudes of the reflected signals are selected.

The inventive method can be applied to measure both angular coordinates of the object. In this case, the indicated actions are performed independently for each angular coordinate.

The inventive method can be implemented both in a single-channel radar, where measurements are carried out sequentially in time, and in a multi-channel (two-channel - monopulse) radar, where signals are received simultaneously by several (two) channels, whose rays are shifted in angular coordinate.

The invention is illustrated by the following drawings.

Figure 1 is a block diagram of a known radar.

Figure 2 is a block diagram closest to the claimed radar.

Figure 3 - block diagram of the inventive radar.

4 is a block diagram of a control device 1.

5 is a block diagram of a beam control device 8.

The inventive method for measuring the angular coordinates of an object is implemented by a radar station (Fig. 3), which contains a serially connected control device 1, a transmitter 2, an antenna switch 3, a receiver 4, a memory device 5, a computing device 6, and also an antenna 7, input / the output of which is connected to the input / output of the antenna switch 3, the beam control device 8, the input of which is connected to the second output of the control device 1, the first output to the control input of the antenna 7, the second output to the second input behind ablation device 5, a device for determining the width of the beam 9, while the third output of the control device 1 is connected to the second input of the computer 6, the first and second inputs of the device for determining the width of the beam 9 are connected respectively to the second and third outputs of the device for controlling the beam 8, its output connected to the third input of the storage device 5.

The inventive radar station can be performed using the following functional elements.

The control device 1 (Fig. 4) and the beam control device 8 (Fig. 5) are made on the basis of a master oscillator 10 and a chain of frequency dividers 11 connected in series with it. As a master oscillator, a self-excitation generator with quartz stabilization can be used. As frequency dividers blocking generators operating in the division mode can be used (Radar devices (theory and construction principles). Edited by V.V. Grigorin-Ryabov, pp. 602-603),

Transmitter 2 - pulse type (Handbook of the basics of radar technology. M., 1967, p. 278).

Antenna switch 3 - is made on a circulator or waveguide bridge (Reference on the basics of radar technology. M., 1967, pp. 146-147).

Receiver 4 - superheterodyne type (Handbook on the basics of radar technology. M., 1967, pp. 343-344).

Storage device 5 - Integrated circuits. Handbook Ed. T.V. Tarabrina, M., Radio and Communications, 1984.

Calculating and solving device 6 is a digital computer that performs calculations by formulas (2).

Antenna 7 - phased antenna array with electronic scanning along one or both angular coordinates and with circular mechanical rotation (Radar Reference. Edited by M. Skolnik. M., Sov. Radio, 1977, v. 2, pp. 132-138 )

The device for determining the beam width 9 is a digital computer that performs calculations in accordance with formula (4).

The operation of the claimed radar when measuring the angular coordinate of the object is as follows. At the command of the control device 1, the beam control device 8 provides signals to the antenna 7, through which the headlight and phase shifters of the headlight are installed in such a way as to provide radiation of the probe signal in the desired (k-m, k = 1,2, ..., i, j, ...) the direction of the radar field of view. A signal proportional to the angular coordinate of the beam θ _k from the second output of the beam control device 8 is supplied to the storage device 5 and stored there. The same signal and a signal proportional to the corresponding angular coordinate of the antenna normal θ _{kн are supplied} from the third output of the beam control device 8 to the first and second inputs of the device for determining the beam width 9, respectively, where the beam deviation from the antenna normal θ _{ke is determined} and taking into account program changes beam width Δ _kn - determination of the antenna beam width Δ _k (in accordance with (4)). The signal from the output of the device 9, proportional to the value of the beam width Δ _k , is fed to the third input of the storage device 5 and stored there. A transmitter signal is formed in the transmitter 2, which, through the antenna switch 3, enters the antenna 7 and is emitted. The signal reflected from the object is received by the antenna 7 and through the antenna switch 3 enters the receiver 4 and then to the storage device 5, where its amplitude U _{k is} stored. At the command of the control device 1, the next direction of the field of view is selected for the emission of the probe signal and the operations are repeated. Thus, during the inspection of the field of view in the storage device 5, the amplitudes of the reflected signals and the corresponding angular positions of the beam and the values of the beam width are recorded. In the computing device 6, two adjacent directions (θ _i , θ _j ) with the largest amplitudes of the reflected signals are selected from all directions of the beam, and the angular coordinate of the object is calculated in accordance with formulas (2).

Thus, the claimed technical solutions allow to increase the accuracy of measuring the angular coordinate of the object, i.e. ensure the achievement of the claimed technical result.

Claims (3)

1. A method of measuring the angular coordinate of an object, including the emission of sounding signals, receiving reflected signals at least at two angular positions of the antenna beam spaced along the angular coordinate, measuring the amplitudes of the received signals corresponding to these positions of the beam, calculating the angular coordinate of the object, characterized in that at each angular position of the beam, the deviation of the beam from the normal of the antenna is additionally determined, its width is determined in accordance with the formula Δ _i = Δ _n / cos (θ _iе ) + Δ _in , Δ _j = Δ _n / cos (θ _jе ) + Δ _jn , where Δ _i , Δ _j is the beam width at the ith and jth (i ≠ j) positions, respectively; θ _ie , θ _je is the measured deviation of the beam from the normal of the antenna during electronic scanning at the ith and jth positions, respectively; Δ _in , Δ _jn is the programmed change in the beam width at the ith and jth positions, respectively; Δн is the beam width at its position on the antenna normal, after which the angular coordinate of the object is calculated. 2. The method according to claim 1, characterized in that the angular coordinate is calculated in accordance with the formulas:

, when Δ _i ≠ Δ _j ;

, when Δ _i = Δ _j = Δ, where θ _o is the measured angular coordinate of the object; θ _i , θ _j are the angular coordinates of the beam at the ith and jth (i ≠ j) positions, respectively; U _i , U _j are the amplitudes of the received signal at the i-th and j-th beam positions, respectively. 3. A radar station, containing a control device, a transmitter, an antenna switch, a receiver, a storage device, a computing device, and an antenna, the input / output of which is connected to the input / output of the antenna switch, a beam control device, the input of which is connected to the second output of the control device, the first output with the control input of the antenna, the second output with the second input of the storage device, the third output of the control device is connected to the second input of the counting o-solving device, characterized in that a block for determining the beam width is introduced, the first and second inputs of which are connected respectively to the second and third outputs of the beam control device, and the output is connected to the third input of the storage device.

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