RU2638174C1 - Method of determining target angular coordinates using linear antenna array - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: radiation of probing signals, reception of reflected signals is performed not less than at two beam positions of the antenna array spaced apart in the angular coordinate, measuring the amplitudes of the received signals corresponding to these beam positions, determining the beam width, based on the beam deflection from the antenna array normal line, for its each angular position, and calculating the angular coordinate of the object. The measurement of the target azimuth relative to the carrier object is performed for a number of times, characterized by a change in the orientation of the carrier object in space. Then for each measurement, a line of possible target positions is aligned with another angular coordinate, taking into account the known pattern of curvature of the linear antenna array in electronic scanning. The lines of the target are shifted in accordance with the change in the orientation of the carrier object in space for the time interval between them and the point of intersection of the shifted lines is found for the target corresponding to the angular coordinates of the target.

EFFECT: increasing the possibility of determining target coordinates when using a linear antenna array.

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Description

The invention relates to radio engineering and can be used in radar to determine the angular coordinates of the target using a linear antenna array.

The prior art method for measuring the angular coordinates of an object (patent for invention RU No. 2274874, published April 20, 2006, IPC G01S 13/00, G01S 13/44). The method includes emitting sounding signals, receiving reflected signals at at least two positions of the antenna beam spaced along the angular coordinate, measuring the amplitudes of the received signals corresponding to these beam positions, calculating the angular coordinate of the object. 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 angular coordinate of the object is calculated.

The disadvantages of this method include the ability to determine only one angular coordinate of the object.

A known method of measuring the angular coordinates of an object (patent for the invention RU No. 2426147, published on 08/10/2011, IPC G01S 13/06). In the method of measuring the angular coordinate of an object in the process of viewing space by a radar station, including the emission of sounding signals, receiving and detecting signals reflected from the object, measuring and storing the levels of received signals and the angular coordinates of the beam corresponding to the received signals, extracting bursts of pulses from each of the received signals objects, calculate the angular coordinate of the object as a result of evaluating the coefficients of the parabolic envelope of the selected pulse packets.

The disadvantages of this method include the ability to determine only one angular coordinate of the object.

A known method for determining the angular coordinates of a source of vertical ground-based HEADLIGHTS (patent for invention RU No. 1840017, published June 27, 2006, IPC G01S 3/14). The method is based on the formation of a sequence of time samples of signals from the receiving channels of the PAR elements vertically, measuring the position of the maximum of the spectrum of this sequence, the value of which determines the angular coordinate, form an additional sequence of time samples of signals from the receiving channels of the PAR in vertical. Moreover, both sequences of samples are separated with respect to each other by a time interval, the duration of which is proportional to the distance between the lower element of the PAR and the surface of the earth, and the angular coordinate is measured by the position of the maximum of the signal spectrum separated by a time interval.

The disadvantages of this method include the ability to determine only one angular coordinate of the object.

Closest to the proposed is a method of measuring the angular coordinate of an object (patent for invention RU No. 2317567, published 02.20.2008, IPC G01S 13/44), which is selected as a prototype. The essence of the method consists in the emission of sounding signals, receiving reflected signals at 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, determining the beam width based on measuring the deviation of the beam from the antenna normal for each of its angular position, calculating the angular coordinate of the object, determining the angular velocity of the object, based on fixing the time interval characterizing the dynamics of changes in the current angle th positions of the object relative setpoint, determining the angular acceleration of the object based on the fixing slot characterizing the dynamics of changes of current values of the angular speed of the object relative to the specified values. The disadvantages of this method include the fact that when it is used, it is possible to obtain information about the angular coordinate of an object in only one plane, usually azimuthal, while the full functioning of most radar systems requires knowledge of two angular coordinates (azimuth and elevation).

It is known that linear antenna arrays have a narrow radiation pattern in the plane in which the antenna array lies (for horizontal antenna arrays, this is the azimuth plane of the target) and a wide radiation pattern in the plane perpendicular to the antenna array line (for horizontal antenna arrays, this is the angle plane target locations). In the first case, the width of the radiation pattern is determined by the size of the antenna array and the amplitude-phase distribution at its aperture, in the second case, the width of the radiation pattern is determined by the properties of a single radiator of the antenna array. Thus, it is believed that linear antenna arrays can determine the position of the target in only one plane.

Currently, radar is increasingly being used at a wide variety of civilian and military installations, while the number of places suitable for installing antenna arrays is very limited. For example, on aircraft, only the leading edges of the wings are suitable for placing additional linear front-view antenna arrays, which allow installing a sufficiently long antenna array in the form of a horizontal line of emitters. Such an antenna array provides measurement of two coordinates of the target - range and azimuth. For a full review of space, you need to know the third coordinate - the elevation angle.

The technical result of the invention is to expand the ability to determine the coordinates of the target when using a linear antenna array with electronic scanning.

The technical result is achieved by the fact that the method of determining the angular coordinates of the target using a linear antenna array includes emitting sounding signals, receiving reflected signals, at least at two positions of the antenna array beam spaced along the angular coordinate, measuring the amplitudes of the received signals corresponding to these beam positions, determination of the first angular coordinate of the target (azimuth). Moreover, it differs from the prototype in that the determination of the second angular coordinate of the target (elevation angle) using a linear antenna array further includes the following steps:

- determine the location of the target relative to the carrier object at certain points in time, when changing its orientation in space;

- measure the angular coordinate of the target (azimuth) for each of these points using a linear antenna array with electronic scanning;

- determine the line of possible positions of the target by the second angular coordinate (elevation angle), taking into account the known nature of the curvature of the directivity pattern of the linear antenna array during electronic scanning for each measured first angular coordinate (azimuth);

- shift the lines of the possible positions of the target in the second angular coordinate (elevation angle) by the amount of change in the orientation of the carrier object in space that occurred during the time interval between them;

- find the intersection point of the shifted lines of the target, which corresponds to the angular coordinates of the target.

The essence of the proposed method for determining the angular coordinates of the target using a linear antenna array is illustrated by the drawings of FIG. 1 - FIG. 3, which presents the following:

FIG. 1 - a family of radiation patterns (LH) of a linear antenna array lying in the horizontal plane during electronic scanning, having a characteristic curvature in elevation, where: target 1, true azimuth of target 2, measured azimuth of target 3;

FIG. 2 - target lines for two measured azimuths corresponding to two positions of the target in space relative to the linear antenna array, where the first position of target 4 is shown, the first measured azimuth 5, the target line for the first measured azimuth 6, the second position of target 7, the second measured azimuth 8, target line for the second measured azimuth 9;

FIG. 3 - the target lines shifted in accordance with the change in the spatial orientation of the carrier object and their intersection point, where: the target displacement after changing the orientation of the carrier object 10, the intersection point corresponding to the true position of the target 11, the line of the possible target position for the second measured azimuth 12 , the target line after changing the orientation of the carrier object.

Using the relationship between the measured and the real azimuth of the target from its elevation angle is the essence of the proposed method.

Determining the elevation angle of the target using a linear antenna array is performed using the characteristics of the directivity pattern of linear antenna arrays, based on the data collected for a certain period on the target azimuth measured by the linear antenna array and the spatial orientation of the carrier (course, roll, pitch), on which the linear antenna grill.

Due to the fact that the geometric figure formed by the common-mode points of the signals emitted by the linear antenna array is a cone whose axis of symmetry is the linear antenna array itself, and the aperture angle depends on the amplitude-phase distribution, the radiation pattern in a plane perpendicular to the scanning plane distorted by a deviation from the normal to the linear antenna array.

Schematically, the pattern distortion pattern of the linear antenna array (BH) is shown in FIG. 1, where a family of radiation patterns of a linear antenna array lying in the horizontal plane is presented, the azimuth zero coincides with the direction of the normal to the linear antenna array.

In the figure of FIG. 1 it can be seen that the degree of distortion increases with an increase in the deviation of the radiation pattern from the normal to the linear antenna array, and an error occurs between the true azimuth of target 2 and the measured azimuth 3, and the magnitude of this error depends on the elevation angle of the target.

As an example of the use of the proposed method for determining the angular coordinates of a target using a linear antenna array, an option is proposed for a moving, changing spatial orientation of a carrier object (for example, an aircraft) equipped with a horizontal linear antenna array. We assume that the detected target is far enough and its motion parameters do not affect its azimuth and elevation relative to the carrier object.

At the initial stage, the target location point relative to the carrier object is determined at a certain point in time (in Fig. 2, point 4).

Using a linear antenna array measure the azimuth of the target (in Fig. 2 - point 5).

The target line is determined taking into account the known pattern distortion pattern (in Fig. 2, line 6).

After a certain period of time, the carrier object changes its orientation in space, and the visible position of the target also changes (in Fig. 2, point 7).

Using a linear antenna array, a second measurement of the target azimuth is made (in Fig. 2, point 8).

The target line is determined, taking into account the known pattern distortion pattern (in Fig. 2 - line 9).

Further, taking into account the known change in orientation in the space of the carrier object and the corresponding displacement of the target position, each point of the target line of the first measured azimuth is shifted to a new target position (in Fig. 3 - the offset of target 10 after changing the orientation of the carrier object), thus , all points of the predicted position of the target form a new line (in Fig. 3 - line 13).

Since it was initially assumed that the angular coordinates of the target relative to the carrier object are practically unchanged (the target is far away and its angular displacements are small), a change in the orientation of the carrier object uniquely determines the relative change in direction to the target. Since the linear antenna array determines only one angular coordinate, the target can be at any of the points forming the target line. If after this the carrier object changes orientation, then after recalculating all the points of the target line, we will get the corresponding points of the shifted target line (in Fig. 3 - line 13), one of which is the true position of the target. Since the true position of the target is unique and it is the same for all shifted lines of the target, the point of intersection of the shifted lines of the target is the true position of the target, since it lies immediately on all lines (there may be ambiguities when there are more than one intersection point, then additional azimuth measurements and to build additional lines of the target to eliminate ambiguity).

Thus, for the example shown in FIG. 3, the intersection of the target line for the second measured azimuth 12 and the target line after changing the orientation of the carrier object 13 obtained by shifting the points of the target line of the first measured azimuth gives the true position of the target, including the azimuth and elevation angle.

Range measurement in this case is carried out by the usual radar method.

Thus, the proposed method for determining the angular coordinates of the target using a linear antenna array allows you to get all three coordinates of the target: range, azimuth and elevation.

The proposed method for determining the angular coordinates of a target using a linear antenna array is universal and involves various uses: cyclic repetitions when tracking a target, using a larger number of measured azimuths and forecast lines to increase accuracy and eliminate possible measurement ambiguities, and using different antenna orientations for linear antenna arrays.

Claims (1)

A method for determining the angular coordinates of a target using a linear antenna array, including the emission of sounding signals, receiving reflected signals for at least two positions of the antenna array beam spaced along the target azimuth, measuring the amplitudes of the received signals corresponding to these beam positions, determining the beam width, the basis of measuring the deviation of the beam from the normal of the antenna array, at each of its angular position, determining the azimuth of the target, characterized in that the measurement of the azimuth of the target relative to the carrier object drive for a number of time points characterized by a change in the orientation of the carrier object in space, after which, for each measurement, a line of possible target positions is built in relation to the elevation angle of the target, taking into account the known nature of the curvature of the directivity pattern of the linear antenna array during electronic scanning, shift the target lines in accordance with what happened during the time interval between them, a change in the orientation of the carrier object in space and find the intersection point of the shifted lines of the target, corresponding conductive target azimuth and elevation target.

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