RU2305853C2 - Device for primary processing of signals of radiolocation station which uses two series of probing impulses - Google Patents

Abstract

FIELD: radiolocation, possible use in impulse radiolocation stations.

SUBSTANCE: claimed device consists of two branches: connected serially, block for detecting far zone signals, block for suppressing far zone signals, received via side leaves of directional diagram of antenna and block for measuring coordinates in far zone and, also connected serially, block for detecting far zone signals, block for suppressing signals of near zone, received via side leaves of antenna directional diagram, block for measuring coordinates in near zone, and decision taking block. Outputs of coordinate measuring blocks in far and near zones are connected serially to first and second inputs of decision taking block, output of which is the output of the whole device.

EFFECT: removal of "blind" zones during detection of targets by radiolocation station using two series of probing impulses.

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Description

The invention relates to radar and can be used in pulsed radar stations (radar).

A feature of modern radars is the use of solid-state transmitting devices built on the basis of high-frequency modules using powerful transistors. Satisfactory use of the capabilities of powerful transistors is achieved with a certain duty cycle of the probe pulses, of the order of 10. At a repetition frequency of 200-250 Hz, the probe pulse duration is 400-500 μs. Since during the radiation the input of the receiver is blocked by the antenna switch, the signals reflected from targets located at ranges of less than 60 km (which corresponds to the duration of the probe pulse of 400 μs) will be truncated and their processing in a matched filter will be suboptimal, leading, firstly , to signal loss and, secondly, to the deterioration of the accuracy of range measurement and resolution in range. One of the possible solutions to this problem is the radiation of not one, but two sequences of probe pulses - the main and additional. The pulse duration of the main sequence τ ₀ is selected from the condition for ensuring the required radar energy potential, and the pulse duration of the additional sequence τ ₁ is selected from the condition for detecting targets at relatively short ranges, with τ ₁ ≪τ ₀ .

, где с - скорость света, а максимальное ее значение определяется размерами зоны «местных предметов» для конкретной позиции РЛС.When using two sequences of probe pulses, the entire working zone of the radar is divided into two sections: the near zone (from the minimum range of the radar D _min to the far border of the near zone D _bz ), in which pulses of an additional sequence are used, and the far zone (from the far border of the near zone D _bz to the maximum range of the radar D _max ), which uses the pulses of the main sequence. The minimum value of the range D _bz in this case is

, where c is the speed of light, and its maximum value is determined by the size of the zone of "local objects" for a particular radar position.

Known radar that uses two sequences of pulses: frequency-modulated pulses with a relatively short duration (pulses of an additional sequence) and relatively long duration (pulses of the main sequence), presented in US patent "Radar systems using two types of pulses" No. 4524361, IPC G01S 13/28, filed April 29, 1982, application No. 372884. Pulses of additional sequence provide detection of targets in the near field. In the far zone, target detection is provided by pulses of the main sequence. The pulse duration of the additional sequence is selected small enough to ensure the detection of targets without compromising accuracy characteristics, starting with the minimum range of the radar. As a result of this, under certain conditions, for example, the presence of active noise interference, flight of a target at an extremely low altitude, or a small value of its effective scattering surface (EPR), the range of target detection by pulses of an additional sequence can be less than the far boundary of the near zone D _bz . This creates the so-called “blind” zone, where target detection by impulses of an additional sequence is already absent, and the pulses of the main sequence are not yet used. The reason for the occurrence of "blind" zones is that the range with which the pulses of the main sequence begin to be used is a fixed value determined by the range D _bz . The presence of "blind" zones is the disadvantage of this radar.

In addition, the radar is known, described in the application No. 2003121688 of July 14, 2003 for the invention "Mobile ground-based two-coordinate radar circular viewing of the meter wavelength range." A patent decision dated 01/26/2005 was received on this application. The patented radar also uses two sequences of pulses: phase-shifted (FM) pulses with a relatively short duration (pulses of an additional sequence) and linear frequency-modulated (LFM) pulses with a relatively long duration (pulses of the main sequence). Pulses of additional sequence provide detection of targets in the near field. In the far zone, target detection is provided by pulses of the main sequence.

The primary processing device for the radar signals of this radar is the closest to the proposed solution for the construction and therefore is taken as a prototype. The structural diagram of the prototype is shown in figure 1, it adopted the following notation:

1 - block detection signals of the far zone (OSD);

2 - block detection signals near zone (OSB);

3 - signal switch;

4 - block suppression of signals received on the side lobes (PBL) of the antenna radiation pattern (BOTTOM);

5 - block measuring coordinates (IR).

The prototype works as follows. From the output of the auto-compensator of noise active interference (not shown in the diagram), the signal is fed to the inputs of the signal detection blocks of the far 1 and near 2 zones.

In block 1, the detection and suppression of non-synchronous impulse noise, coordinated filtering of the LFM signal, coherent accumulation of the azimuthal burst of pulses, and the detection of echo signals against the background of the receiver's own noise are performed.

Block 2 provides radar protection from non-synchronous impulse noise and from passive interference in the area of "local objects", consistent filtering of the FM signal, incoherent accumulation of the azimuthal burst of pulses and detection of echo signals against the background of the receiver's own noise.

In the signal switch 3, information from the signal detection units of the two zones is combined. The signal switch is controlled by a circular gate (strobe "M"), the duration of which is set by the operator based on the size of the "local objects" zone for a specific radar position.

From the output of the switch 3, the signal enters through block 4, which eliminates the reception of signals along the side lobes of the bottom beam, to the input of the coordinate measurement unit 5, in which the azimuth and range of the target are measured. According to the measurement results, the corresponding codograms are generated, which are transmitted to the display, control and monitoring devices and secondary processing of radar information and interfaces (not shown).

In the presence of the above conditions (the presence of active noise interference, the target’s flight at low altitude or a small ESR of the target), blind spots can also appear in this radar, which is its drawback.

The technical result of the invention is the elimination of "blind" zones when detecting radar targets using two sequences of probe pulses.

It is proposed to eliminate “blind” zones due to the fact that the range with which the pulses of the main sequence begin to be used is adaptive for each target and interference environment within the near zone, in contrast to the prototype, in which the specified range is a fixed value.

The structural diagram of the proposed device for primary signal processing is shown in figure 2. The following notation is adopted on the diagram;

1 - block detection signals of the far zone (OSD);

2 - block detection signals near zone (OSB);

3 - block suppression of far-field signals received on the side lobes of the bottom (PBLD);

4 - block suppression of near-field signals received on the side lobes of the bottom (PBLB);

5 - block measuring coordinates in the far zone (ICD), the first block measuring coordinates;

6 - block measuring coordinates in the near field (ICB), the second block measuring coordinates;

7 - decision block.

To obtain the above technical result, the signals at the outputs of the signal detection units of the far and near zones, unlike the prototype, are not combined by the signal switch, but are processed independently in the signal suppression units received on the side lobes and coordinate measurement units. Combining and analysis of coordinate information obtained using pulses of the main and additional sequences is carried out in the decision block.

The proposed device for primary signal processing consists of two branches: connected in series to the OSD block 1, the PBLD block 3 and the ICD block 5, and also connected in series to the OSB 2 block, the PBLB block 4 and the ICB block 6. The outputs of the ICD 5 and ICB 6 blocks are connected respectively with the first and second inputs of the decision block 7, the output of which is the output of the entire device.

As pulses of both the main and additional sequences, you can use any complex signals (frequency-modulated, phase-shifted, etc.).

The inventive device for the primary signal processing of a radar station using two sequences of probe pulses, operates as follows.

The signal from the output of the auto-compensator of active interference (not shown in the diagram) is fed to the inputs of the OSD 1 and OSB 2. In the OSD 1 unit, non-synchronous impulse noise is detected and suppressed, matched filtering of the main sequence pulses, accumulation of the azimuthal burst of pulses, as well as detection of the echo signals against the background noise of the receiving device.

The OSB 2 block protects the radar from non-synchronous impulse noise and from passive interference in the area of "local objects", coordinated filtering of pulses of an additional sequence, accumulation of an azimuthal burst of pulses and detection of echo signals against the background of the receiver's own noise.

From the outputs of the OSD 1 and OSB 2 blocks through the PBLD 3 and PBLB 4 blocks, which eliminate the reception of signals along the side lobes of the DND, the signals are received respectively at the input of the ICD 5 and IKB 6 blocks, in which the target coordinates are measured. From the outputs of these blocks, information about the coordinates of the target is transmitted, respectively, to the first and second inputs of the decision block 7.

The functions performed by the OSD, OSB, PBLD, PBLB, ICD and ICB blocks are similar to the functions performed by these blocks in the prototype device. Let us consider in more detail the purpose of the decision block 7.

The entire range of the radar range is divided into two sections: the first - from D _min to the far border of the near zone D _bz , the second - from D _bz to the range D _max . Schematically, this is shown in figure 3.

It has already been noted above that “blind” zones arise under certain conditions, such as the presence of active noise interference, flight of a target at low altitude, or a small ESR of the target. To eliminate the "blind" zones in such conditions, it is proposed, along with an additional sequence of probing pulses, to use targets for detection in the near zone and pulses of the main sequence. The decision on the use of pulses of the main sequence in the near field is made in decision block 7.

The algorithm of the decision block 7 is as follows. If the coordinates of this target were measured both in the ICD block 5 and in the ICB block 6 (that is, the target is found in the far and near zone signal detection blocks), then the coordinates of the target obtained in the ICB block 6 are output to the decision block 7 while the coordinates of the target were measured only in the ICD block 5 (that is, the target was not detected in the near-field signal detection block), the coordinates obtained in the ICD block 5 are output to the output of the decision block 7.

Thus, adaptively using the pulses of the main sequence in the near field, the present invention allows to eliminate the "blind" zone when detecting radar targets using two sequences of probe pulses.

Claims (1)

A device for primary processing of radar signals, consisting of blocks for detecting signals of the far and near zones, a block for measuring coordinates and a block for suppressing signals in the far zone received from the side lobes of the antenna radiation pattern, the output of which is connected to the input of the first block of coordinate measurement, characterized in that the block is introduced decision making, block suppression of near-field signals received on the side lobes of the antenna radiation pattern, and a second coordinate measurement unit, while the output of the detection unit the signal of the far zone signals is connected to the input of the block suppressing signals of the far zone received on the side lobes of the antenna radiation pattern, the output of the first block of coordinate measurement, which is the block for measuring coordinates in the far zone, is connected to the first input of the decision block, the output of the block for detecting signals of the near zone is connected with the input of the block of suppression of near-field signals received along the side lobes of the antenna radiation pattern connected by the output to the input of the second coordinate measurement unit, which is having a unit for measuring coordinates in the near field, the output of the latter is connected to the second input of the decision-making unit, the output of the latter is the output of the entire device.

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