RU2618675C1 - Method of space radar scanning - Google Patents

Abstract

FIELD: radar.

SUBSTANCE: invention relates to radar ranging and may be used for synchronous repeater jamming (SRP) recognition. Screening of directions at different elevation angles is carried out by probing signals with changed parameters, making decision on false targets detection at all elevation angles at distances, at which detected signals with previous parameters and with changed ones, received in zone where reception of reflections from targets is unlikely or impossible. Said technical result is also achieved by fact, that zone, where reception of reflected from target signals is unlikely or impossible, is considered to be zones located outside direct visibility and beyond radar maximum range, in area of shadows (tones) and at heights, unachievable for detected class of real targets. Said technical result is also achieved by fact, that probing signal linear frequency modulation law is changed to inversed one, as well as by fact, that as false target are considered signals received in entire elevation column at distances, at which signals with changed parameters are detected and within line of sight, if they are correlated with signals received in zone, where reception of signals reflected from targets is unlikely or impossible, besides, signals are considered to be correlated if signals received from one direction at different distances have similar levels in signals linear reception mode and in signals receiving mode with limitation or their autocorrelation functions are equal.

EFFECT: recognition of false targets generating synchronous repeater jamming signals.

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Description

The invention relates to the field of radar and can be used to recognize synchronous response interference (SOP).

Big problems for the operation of radar stations (PPS) create impulse noise with a structure close to the structure of the probing signal. For a jammer, impulse noise is the most energy-efficient. Particular cases of pulsed interference are synchronous response interference [Protection against radio interference, ed. M.V. Maksimova, Moscow: Sov. Radio, 1976, p. 60], which are emitted by the response interference director (POP) only after receiving the sounding signal, and non-synchronous impulse noise, which the director of the pulse interference emits, regardless of the reception of the sounding signal based on previously explored radar parameters. As a result of their actions, false detection of targets occurs, since the received interference signals do not differ in structure from signals reflected from the targets. The high efficiency of the response interference is achieved by the fact that the interference director re-emits an amplified copy of the probe signal, regardless of its level. This provides a radar view of the space that affects the radar not only in the main beam, but also along the side lobes of the antenna pattern (BOTTOM), resulting in a large number of false signals (marks), stationary, in the simplest case, or moving with the installed the director of the interference speed, in the case of synchronous response interference. In all cases, interference pulses are perceived as signals reflected from targets, therefore, they capture and tie the path along them [S.Z. Kuzmin. Fundamentals of designing systems for digital processing of radar information, M .: “Rad. and communication ”, 1986, p. 109] with its subsequent reset in the case of non-synchronous impulse noise or the maintenance of a false path, in the case of synchronous response interference with a varying delay. From this it follows that the SOP is most effective, since the false target it forms will be followed at all range intervals, while false targets formed by non-synchronous interference will be periodically reset from tracking.

There is a known radar method for viewing space, based on the formation of a carbon-bearing packet of pulses received in one range interval (strobe) [ibid.]. Under the action of non-synchronous interference, the moments of reception of pulses are random, therefore, in different periods of sounding, they fall into different gates, the path along them is not tied, which is a sign of interference.

The disadvantage of this method is that it does not provide recognition of synchronous response interference.

Known closest to the claimed method of radar survey of space [Handbook of radar ed. M. Skolnik, v. 4, p. 72, Moscow: “Sov. Radio ”, 1978], based on scanning the beam of the bottom beam in the elevation and azimuthal planes and consisting in sequential inspection of the angular directions when electronically scanning the beam of the bottom of the radar from the elevation angle with the simultaneous rotation of the antenna in the azimuthal plane, thus forming angle columns of the examined directions ( Fig. 1).

The advantage of this method is the possibility of a three-dimensional overview of the entire space of a single-position, single-beam radar.

A drawback of the closest method for radar space viewing is that when radars are exposed to powerful synchronous response interference in one of the angular directions, the false targets formed by them will be detected immediately in the entire elevation column due to the reception of interference signals in the area of the bottom side lobes and impossibility their suppression. But it is possible to exclude overloading of devices for processing and tracking target traces without suppressing interference, if it is recognized.

Thus, the task (technical result) of the proposed method is the recognition of synchronous response signals that form false targets.

The problem is solved by using the properties of signals emitted from one point, determining and periodically updating the parameters of these signals during operation and using them as standards for interference signals.

The task (technical result) in the method of radar viewing of space, based on scanning the beam of the DND in the elevation and azimuthal planes and consisting in a sequential inspection of the angular directions, is achieved by the fact that according to the invention, the inspection of directions at different elevation angles is carried out by probing signals with changed parameters, take the decision to detect false targets at all elevation angles at ranges at which signals with the same parameters and with changed and adopted in an area where reception of reflections from unlikely or impossible goals.

The task (technical result) is also solved by the fact that the zone where reception of reflections from targets is unlikely or impossible is considered zones located outside the line of sight and for the maximum range of the radar, in the area of shadows (penumbra) and at heights unattainable for the purposes discovered class.

The task (technical result) is also solved by the fact that the law of linear frequency modulation of the probe signal is changed to mirror.

The task (technical result) is also solved by the fact that the signals received in the entire elevation column at ranges at which signals with altered parameters and within line of sight are detected as a false target if they are correlated with signals received in the area where the reflections are received from goals is unlikely or impossible. The task (technical result) is also solved by the fact that the signals are considered correlated if the signals received from the same direction at different ranges have the same levels in the linear signal reception mode and in the signal reception mode with restrictions or their autocorrelation functions are equal.

The essence of the method is as follows.

If there is a response jammer in the area being examined by the radar, then, after receiving the radar signal, it begins to emit interference in the form of its copies. Moreover, taking direct radar signals, he can receive them while in the area of the side lobes of the bottom (and even the background) at large distances from the radar. The radar receives these POP signals, including the bottom side lobes of the BOTTOM (since it is affected by a direct powerful signal emitted by the POP), as reflected signals from targets in the entire elevation column. To identify false targets when examining the next direction of radiation in the elevation column or during the next radiation of the probe signal in the same direction, its parameters are changed and all received signals with previous parameters are considered false targets. These signals are a false target that must be recognized. In FIG. 2 is a diagram explaining the distribution in time of: radar probe signals (FIG. 2a); signals emitted by POP after irradiation with probing signals (Fig. 2b); signals arriving at the radar input (Fig. 2c), and unrecognized signals (Fig. 2d). It can be seen from the above diagrams that on the range range to POP equal to D _pop = t _pop × C (where C is the speed of light, at _pop is the propagation time of the signal from POP to the radar), a false target is recognized, but at ranges beyond D _pop (Fig. 3) and to the end of the instrumental range of the radar, equal to D _and = T × C (where T is the probe signal repetition period), the false target is not recognized and its signals will be perceived as reflected from the targets, since the POP after receiving the probe signal with altered parameters begins to radiate its amplified copies. Those. if the POP is further than the instrumental range D _{and the} radar, then all false targets will be recognized in the entire elevation column, and in the case when the POP is at a distance D _pop less than the instrumental range D _and false targets at ranges greater than the distance D _pop are not recognized . In this case, additional measures are used to ensure the recognition of false targets. Namely, all signals are considered false targets if they are taken in the shadow (penumbra) region [Golev K.V. Calculation of the range of radar stations, M .: “Sov. Radio ”, 1962, p. 33], for example, at ranges beyond the direct visibility of the radar equal to D _mountains = t _mountains × C (where t _mountains is the propagation time of the signal within the line of sight at the lower corners of the elevation column), either at an elevation or at ranges above the limit heights N achieved by the goal of the discovered class (Fig. 3). The latter case can be implemented in radars capable of recognizing the target class by the parameters of the signals. Also, signals with altered parameters received within the D _mountains in the direction of D _{i are} also considered false targets if these signals are correlated with signals detected outside the direct visibility of the D _mountains in the direction D. Signals are considered correlated if the levels received from one direction of the signals are the same in the mode of linear signal reception or in the mode of receiving signals with restriction or their autocorrelation functions are equal. The equality of the amplitudes of the signals received at different ranges in the linear mode or in the limited mode (this means the identity of their phase structure), as well as the equality of their autocorrelation functions, is a sign of the emission of signals from one source from one point.

In the case of using a probing signal with frequency modulation to maintain the ability to select moving targets, changing its parameters is performed by changing the modulation law to mirror.

The invention is illustrated by drawings:

FIG. 1 is a diagram explaining the formation of an elevation column;

FIG. 2 is a diagram explaining a review method;

FIG. 3 is a diagram illustrating visibility restrictions on height, horizon, and elevation.

In FIG. 1 illustrates the process of formation of an elevation column in the process of electronic scanning of the main beam of the DND in elevation when the entire antenna is rotated in the azimuthal plane.

In FIG. 2 illustrates the temporal process of reviewing space. The review consists of the active work of the radar when a probing signal with changed parameters is emitted in a given direction after each sensing period (Fig. 2a) and when the POP re-radiates the signals of the probing signal a with the previous parameters and changed (Fig. 2b). In FIG. 2c shows the signals re-emitted by POP and received radar with the old and changed parameters. In FIG. 2d shows the remains of unrecognized signals. Interference signals with altered parameters that fall into the interval of receiving signals with altered parameters remain unrecognized (these are interference signals received at a range from POP). If signals with changed parameters are received, but from heights unattainable for the purposes of the detected class, or from the shadow region (penumbra), then they are also an obstacle.

In FIG. Figure 3 illustrates the process of a spatial survey of different zones and the associated signal reception restrictions, in particular, the detection limit in height H, above which the targets of the detected class cannot appear regardless of range, as well as the limitations of direct visibility in the shadow region arising behind an elevation or horizon or in partial shade.

Thus, the task is solved and a technical result is achieved.

Claims (5)

1. The method of radar viewing of space, based on scanning the beam pattern of the antenna in the elevation and azimuthal planes and consisting in a sequential inspection of angular directions, characterized in that the inspection of directions at different elevation angles is carried out by probing signals with changes in parameters that ensure separation of these signals, take decision to detect false targets at all elevation angles at ranges at which signals with the same parameters and with changed in an area where receiving reflections from targets is unlikely or impossible. 2. The method according to p. 1, characterized in that the zone where the reception of reflections from the target is unlikely or impossible is considered to be zones located beyond the line of sight and for the maximum range of the radar station, in the area of shadows (penumbra) and at heights unattainable for the purposes of the discovered class. 3. The method according to p. 1, characterized in that the law of linear frequency modulation of the probe signal is changed to mirror. 4. The method according to claim 1, characterized in that the signals received from one direction at ranges at which signals with changed parameters and within line of sight are detected as a false target, if they are correlated with signals received in the area where the signals are received reflected from goals is unlikely or impossible. 5. The method according to p. 4, characterized in that the signals are considered correlated if the signals received from the same direction at different ranges have the same levels in the linear signal reception mode and in the signal reception mode with restrictions or equal to their autocorrelation functions.

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