RU2157550C1 - Method of detection of group objects - Google Patents

Abstract

FIELD: radiolocation. SUBSTANCE: invention can find use in radars controlling air traffic or air space. Invention is aimed at solving of technical problem of detection of unresolved group objects spaced by angular coordinates. Method is based on usage of property when various methods of direction finding of group unresolved objects generate incompatible bearings. In this case direction finding is carried out by two or more methods at same time and decision on presence of unresolved group objects is taken if spread of obtained values of bearing exceeds threshold value. To obtain this direction finding is conducted with the aid of single-channel and monopulse methods. Bearing is found by direction of reception of emission of airborne radio electronic facilities and with the use of single-channel or/and monopulse methods. EFFECT: enhanced reliability of detection of unresolved group objects. 2 cl

Description

 The invention relates to the field of radar and can be used in promising radars for air traffic control and for airspace control.

In the process of control and monitoring, it is necessary to know the exact coordinates of all objects located in space, to resolve objects separated by angular coordinates by 1-2 ^o , to detect (recognize) group objects if it is impossible to resolve them.

 The resolution in angular coordinates is provided through the use of antennas of appropriate sizes, since the possibility of resolution is determined by the beam width, DND, which in turn is proportional to λ / d (λ is the radar wavelength; d is the linear size of the antenna aperture).

 The disadvantage of this method is that in the long wavelength range at real values of d it is not possible to provide the above resolution. In this case, the task is to at least detect the presence of a group object, after which a short-wave radar can be used to resolve objects within the group (Patent No. 2126543). You can detect a group object based on its direction finding.

 There are various methods of direction finding, for example, direction finding of radiations of on-board radio-electronic means of an object (Handbook of Radar, ed. M. Skolnik, M., "Sov. Radio", 1978, v. 4, p.206). The fact of receiving from the direction in which the long-wave radar has detected an object, more than one bearing will indicate the detection of a group object. The disadvantage of this method is that only one object can emit from a group of objects. For example, with a paired object and the presence of radiation of only one of them, the method gives one bearing to the radiating object.

The known single-channel method of direction finding of an object by measuring the angular position of the center of the packet of reflected signals (Theoretical Foundations of Radar, under the editorship of Ya.D.Shirman, M., "Sov. Radio", 1970, p.274). The disadvantage of this method is that using this method, the coordinates of the center of the total packet of reflected signals from a group of objects will be determined, including these coordinates can correspond to the false position of the object. So, for example, with a pair of unresolvable objects, this method gives a bearing between objects (with equal power of the signals reflected from them). The most commonly used technical solution is a single-pulse direction finding method, in particular, based on the reception of signals with a total radiation pattern (DN _Σ ) and differential (DN _Δ ), by comparing the amplitudes of the received signals and determining the bearing direction (Ibid., P. 301, 5.18 , as well as A.I. Leonov, K. I. Fomichev. Monopulse radar, M., Radio and communications, 1984, pp. 70-71, III). The magnitude of the signal received by _{Δ Δ} determines the degree of deviation of _{Δ Σ} from the bearing to the object (Theoretical Foundations, p.302, 1st paragraph above), if it is zero, then the direction of Δ _Σ corresponds to the bearing.

 The disadvantage of this method is that it is not applicable for direction finding in the case of unresolvable group objects spaced in angular coordinates, because in this case, there will be a distortion of the phase front of the wave incident on the antenna, and the method may produce false bearings.

 Consider this in more detail.

1. The signal of the difference channel U _Δ ≠ 0.

Three cases are possible:
a) a single object was detected, the _{Σ Н} deflected from the bearing on it;
b) an unresolvable group object has been detected, the direction of the beam _Σ does not coincide with the bearing to any of the objects;
c) an unresolvable group object is detected, the direction of the _{Σ Н} coincides with the bearing to one of the objects.

2. U _Δ = 0
Two cases are possible:
a) a single object is detected, the direction of the _{Σ Н} coincides with the bearing;
b) an unresolvable group object has been detected, the direction of the Δ _Н does not coincide with the bearing to any of the objects (the method gives a “false” bearing).

 An analysis of these cases shows that when using the total-difference direction finding method it is impossible to decide on the presence of an unresolvable group object, therefore this method is used for direction finding of a single object. Thus, the disadvantage of the above direction finding methods is that they can give a false bearing on group objects, the position of which depends on the composition of group objects and the properties of a particular direction finding method. It follows that bearings on a group object obtained in various ways, as a rule, will not coincide.

 The invention is aimed at solving the following problem: the detection of unresolvable group objects spaced in angular coordinates.

 This problem is solved on the basis of using the property that the different methods of direction finding by group unresolvable objects give mismatching bearings.

 This result is achieved by the fact that in the detection method of unresolvable group objects based on direction finding, according to the invention, direction finding is carried out simultaneously in two or more ways and a decision is made on the presence of unresolvable objects if the spread of the received values of the bearing exceeds a threshold value.

 The fact that direction finding is carried out using single-channel and monopulse methods.

 The fact that the bearing is determined in the direction of reception of emissions of on-board electronic equipment and using single-channel or also monopulse methods.

 The essence of the invention is as follows. When reviewing space and detecting, for example, two identical and unresolvable objects, the single-channel method gives a bearing between objects, and a bearing by radiation gives one of the objects. Bearing values will differ by an amount equal to half the angular separation of objects, which will be detected when comparing their values. If there are three objects, the reception of radiation from the middle object and the other two are in a symmetrical position relative to it, the attribute of a group object can be skipped. To reduce the likelihood of skipping, a single-pulse direction finding method can also be used.

Claims (3)

 1. A method for detecting unresolvable group objects based on direction finding, characterized in that direction finding is carried out simultaneously in two or more ways and decide on the presence of unresolvable group objects if the scatter of the received values of the bearing exceeds a threshold value.  2. The method according to claim 1, characterized in that the direction finding is carried out using single-channel and monopulse methods.  3. The method according to claim 1, characterized in that the bearing is determined in the direction of reception of radiation of the on-board electronic equipment and using single-channel or also single-pulse methods.