RU2610833C1 - Space scanning method - Google Patents

Abstract

FIELD: radars.

SUBSTANCE: invention relates to radar ranging and intended for construction of surveillance radar stations with digital antenna arrays. According to method in each beam pattern bearing position in transmission mode digital antenna array generates radial transmitting beam pattern in elevation plane, in receiving mode received reflected signals from antenna elements outputs are presented in form of digital readings, of which through weighted summation receiving directivity diagram multi-beam in elevation plane with needle-shaped beams is generated, wherein adjacent beams are overlapped by level of half-power, at objects detection, measurement of their range and elevation coordinates single-pulse signal processing method of each of adjacent pairs of receiving beams is used, wherein detected objects bearing coordinate is directivity pattern current bearing position.

EFFECT: achieved technical result is reduction of scanning time and increasing accuracy of objects coordinates measuring.

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Description

The invention relates to radar technology, and in particular to methods of viewing space, and is intended for use in radar systems (radar) with digital antenna arrays (CAR).

A known method of reviewing the space [1 - p. 39 - Signal processing in multi-channel radar / Ed. A.P. Lukoshkina. M .: Radio and communication. 1983. - 328 p.] By means of a parallel survey over all measured coordinates using a multi-beam radar, and overlapping radiation patterns (DF) are formed, covering the entire viewing area.

The disadvantages of this method are the excess resources that are required for the formation of parallel rays along all measured coordinates.

A known method of reviewing space [2 - p. 233 - Belotserkovsky GB Basics of radar and radar devices. M .: Sov. radio. 1975 - 336 S.], in which a multipath beam is formed in the elevation plane due to the irradiation of the mirror antenna by several emitters (horns), while the line of emitters is located in the elevation plane and is fixed relative to the mirror axis, each emitter is connected to its transceiver by a separate feeder and forms partial beam at its carrier frequency. The reception of reflected signals by each emitter is also carried out at its own frequency. Azimuth scanning is performed by mechanical rotation of the antenna.

The disadvantages of this method of viewing space are:

- low efficiency of the transmitting part of the device due to the large losses of the emitted and received signal in the feeders connecting the emitters (horns) and transceiver channels, since they are significantly spaced in space;

- insufficiently high reliability, since in case of failure of one transceiver, a review of the space becomes impossible in the sector of elevation viewing, which this transceiver provided.

Closest to the technical nature of the invention is a method of reviewing space [3 - Method for reviewing space and tracking surface objects during low-altitude flight - Patent RF 2211459, publ. 08/27/2003], taken as a prototype, which consists in the fact that the detection of objects includes sequential processing of data in discrete time with reference to each current measure t _{n of the} processing obtained by reviewing the space using a fan radiation pattern and occupying M horizontal positions and diagrams directivity with a needle shape probing individual selected portions of the viewing area with a short viewing period, while both radiation patterns are formed by a single antenna system with electronic control beam.

The disadvantages of the prototype include:

- a long survey time, since the measurement of the object’s coordinates is carried out in two stages: first, a fan beam in the receiving and transmitting mode is used, while a rough measurement of the object’s coordinates is performed, and to clarify the coordinates, a beam with a needle shape is additionally used, which significantly lengthens the viewing time when increasing the number of objects;

- insufficient accuracy of measuring the coordinates of the object, because the measurement uses the only MD with a needle shape, and the maximum method [2 - p. 87].

The task to which the invention is directed is to reduce the viewing time and improve the accuracy of measuring the coordinates of objects.

To solve this problem, we propose a space survey method in which data is processed sequentially in discrete time with reference to each azimuthal position of the radiation pattern, while the space survey is carried out by a fan radiation pattern sequentially occupying M positions in azimuth and a needle-shaped radiation pattern, while both radiation patterns form one antenna system with electronic beam control.

According to the invention, a multi-element digital antenna array is used to form transmit and receive radiation patterns, while in each azimuthal position of the radiation pattern in the transmission mode, a probing signal is amplified in a solid-state power amplifier built into each transceiver channel by a digital antenna in the form of a fan-shaped radiation pattern in the elevation plane lattice, and transmit it along the connecting circuit of minimum length to the ant connected to this channel the received element, in the reception mode, the reflected signals received from the output of each antenna element are represented in the form of digital samples, from which, by weighted summation, a receiving multi-beam radiation pattern in the elevation plane is formed, each beam of which has a needle shape, while adjacent rays overlap in level half power, and the width of the receiving and transmitting radiation patterns corresponds to the angular size of the detection zone in the elevation plane, objects are detected, measured Measurement of their range and elevation coordinate by a single-pulse method of processing signals from each of the neighboring pairs of receiving beams.

The technical result of the proposed method is to reduce the viewing time and improve the accuracy of measuring the coordinates of objects.

A comparative analysis of the claimed method and prototype shows that their difference is as follows:

- in the prototype, a review of the space is carried out in two stages - a rough determination using a fan pattern and refinement by scanning a single needle-shaped pattern. These actions must be performed sequentially in real time. Moreover, to clarify the coordinates of several objects, it is necessary to sequentially scan the needle pattern in several areas of space, which takes the longer, the more objects. In the proposed method, the survey of space is carried out in one step, and due to the formation of a multi-beam pattern, each beam of which has a needle shape, and neighboring rays overlap at half power level, the measurement of the coordinates of all objects is provided immediately for all objects, thereby reducing the viewing time;

- in the prototype, the coordinates of the object are refined using a needle-shaped pattern scanning using the maximum method. The proposed method uses monopulse signal processing of each of the adjacent pairs of receiving rays of the formed multipath beam, which provides a significant reduction in measurement error [2 - p. 91] compared with the maximum method used in the prototype.

The combination of distinguishing features and properties of the proposed method of reviewing space from the literature is not known, therefore, it meets the criteria of novelty and inventive step.

In FIG. 1. The structural diagram of a device that provides the implementation of the proposed method.

In FIG. 2. The structural diagram of the control system and digital chart formation is shown.

In FIG. 3. The structural diagram of the frequency converter is shown.

In FIG. 4. The block diagram of the control module and digital signal processing is shown.

When implementing the proposed method, the following sequence of actions is performed:

- in each azimuthal position, the radiation patterns in the transmission mode form a fan transmitting radiation pattern in the elevation plane using a multi-element digital antenna array, while the probing signal is amplified in a solid-state power amplifier built into each transceiver channel of the digital antenna array, and it is transmitted through a connecting circuit minimum length per antenna element connected to this channel - 1;

- in the reception mode, the reflected signals received from the output of each antenna element are presented in the form of digital samples - 2;

- from the obtained digital readings, a multi-beam receiving radiation pattern is formed in the elevation plane by weighted summation, each beam of which has a needle shape, while adjacent rays overlap at half power level, and the width of the receiving and transmitting radiation patterns corresponds to the angular size of the detection zone in the elevation plane - 3;

- perform the detection of objects, measuring their range and elevation coordinates using a single-pulse method of processing signals from each of the adjacent pairs of receiving rays - 4;

- establish the following azimuthal position of the radiation pattern and perform the listed operations for this position - 5.

The proposed method can work both with electronic scanning of the azimuth day with a fixed digital antenna array (CAR), and when scanning the beam in azimuth due to the mechanical movement (rotation) of the CAR.

Implementation of the proposed space survey method is possible, for example, using a device including (Fig. 1) CAR 1, control unit (CU) 2, the first control output of which is connected to the control input of CAR 1, the second control output to the control input -the rotary device (OPU) 3, the third control output to the control input of the unit for detecting and measuring the coordinates of objects (BOIKO) 4, and the input to the output of BOIKO 4.

CAR 1 includes N transceiver modules (PPM) 5, a system for the formation and distribution of signals (SFRS) 6 and a control system and digital chart formation (SUDSDO) 7.

SFRS 6 has N outputs of the probing signal (ЗС) connected to the inputs of the ЗС ППМ 5, N outputs of the sampling Фд, connected to the inputs of the sampling ППМ 5, N outputs of the local oscillator Fget, connected to the heterodyne inputs of the ППМ 5.

PPM 5 contain series-connected phase shifter (PV) 8, solid-state power amplifier (PA) 9, circulator 10 and antenna element (AE) 11. To the output of the circulator 10 are connected in series low-noise amplifier (LNA) 12, frequency converter (PFR) 13, the heterodyne input of which is the PPM 5 heterodyne input, and the control and digital signal processing module (MUCOS) 14, whose sampling input is the PPM 5 sampling input.

The data output of MUCOS 14 is the data output of the PMP 5 and is connected to one of the N data inputs of the control system 7, the control input of the MUCOS 14 is the control input of the MPCS 5 and connected to one of the N control outputs of the control system 7. The first, second and third control outputs of the MUCOS 14 are connected respectively, with the control inputs of the RFP 13, UM 9 and phase shifter 8. The data output of the control system 7 is connected to the data input of BOIKO 4.

SUTSDO 7 (Fig. 2) has K formers 15 in the number of generated beams, each of which contains N channels, while the inputs of i-channels in the formers 15 are combined. Each channel of the shaper 15 contains a multiplier 16, the first input of which is the input of the channel, the output of the read-only memory (ROM) 17 is connected to the second input, and the output of the multiplier 16 is the output of the channel and connected to one of the N inputs of the digital adder 18, the output of which is connected to one of the K inputs of the interface (I) 19. The output of the interface 19 is the output of the control system 7. The control device (CU) 20, the input of which is the control input of the control system 7, has N + 1 control outputs, which are the control outputs of the control system 7 All blocks SUTSDO 7 can be performed depending on the number of PPM 5 and the number of rays K in the form of one or more programmable logic integrated circuits (FPGA).

RFP 13 (Fig. 3) is a series-connected mixer (SM) 21, the input of which is the input of the RFI 13, and the local oscillator input is the heterodyne input of the RFI 13, and an intermediate frequency amplifier (IFA) 22, the output of which is the output of the intermediate frequency (IF) ) RFI 13, and the control input - the control input of the RFI 13.

MUCOS 14 (Fig. 4) is a series-connected analog-to-digital converter (ADC) 23, the input of which is the input of the MUCOS 14 IF, and the clock input is the sampling input of MUCOS 14, and the control and processing unit (CUO) 24. The first, second and the third control outputs of the BUO 24 are respectively the first, second, and third control outputs of the MUCOS 14. The data output and the control input of the BUO 24 are the data output and the control input of the MUCC 14, respectively.

SFRS 6 is a three frequency synthesizer, providing the formation of the probing signal ZS, the signal of the sampling clock frequency Fд and the local oscillator signal Fget. In this case, for example, synthesizers from [4 - pp. 142-143. Mini-Circuits. RF & Microwave components guide. 2010]. The signals generated in the synthesizers are branched into N outputs using power dividers [4 - p. 136-140].

BOIKO 4 is a computer that provides processing of signal samples according to a given algorithm.

BU 2 is a computer that provides control over the operation of devices CAR 1, OPU 3 and BOIKO 4, as well as displaying the coordinates of detected objects.

OPU 3 is a device that ensures the rotation of CAR 1 in the azimuthal plane, and can be performed on the basis of a slewing ring with a bearing and a worm shaft with an electric motor.

The device can work both with electronic scanning of the azimuth of the azimuth while the CAR 1 is stationary, and when scanning the azimuth of the azimuth due to the mechanical rotation of the CAR 1 using the OPU 3. The azimuth scanning sector in the first case is limited by the characteristics of CAR 1, and in the second case it is 360 °.

In each azimuthal position of the radiation paths in the transmission mode, a fan transmitting radiation pattern is formed in the elevation plane using CAR 1. The transmitting power path is formed by setting the required phase and amplitude ratios in CAR 5 from the CAR 1 structure by adjusting the phase shift of the probing signal ZS in phase shifters 8 and the coefficient amplification of power amplifiers UM 9.

For the case of a flat rectangular CAR, the aperture of which contains N _x AE 11 installed along the X coordinate at a distance d _x , and N _y AE 11 installed along the Y coordinate at a distance d _y , the radiation pattern F (ϕ, θ) is defined as [ 5 - p. 27-28, Kuzmin S.Z. Digital radar. Introduction to the theory. - QUIEC. 2000]:

Where

where A _xi , A _yi are the coefficients of the amplitude distribution in PA 9 connected to AE 11, which are located along the coordinates X and Y, respectively;

ψ _xi ψ _yi are the phase distribution coefficients presented in the form of phase shifts in the phase shifters 8 connected through the PA 9 and circulator 10 to the AE 11, which are located along the X and Y coordinates, respectively.

For ground surveillance radars, the fan beam may have a cosecance shape [6 - Fig. 5.1 b - Bakulev P.A. Radar systems. M .: Radio engineering. 2007. - 376 p.]. This form of the DN is formed by setting the corresponding amplitude and phase coefficients in the power amplifiers 9 and phase shifters 8, for example, as described in [7 - E. Lopatenko, A. A. Marusich Cosec antenna pattern with low side lobe. // Radio engineering, 2006, No. 12, p. 49-53.].

After amplification of the probe signal ZS in the PA 9, it enters the antenna element (AE) 11 connected to this channel via a connecting circuit of minimum length.

After the radiation of the probing signal, the AP CAR 1 switches to the reception mode.

In the receiving mode, the received reflected signals from the output of each AE 11 in each APM 5 pass through the circulator 10, amplified in the LNA 12, converted in frequency to the RFI 13 and presented as digital samples S _mn (t) using the ADC 23.

From the obtained digital samples, a multi-beam receiver is formed in the elevation plane of the beam with needle-shaped rays by weighted summation in the control system 7. The samples of the i-th beam with the maximum direction ϕ _i , θ _i are calculated by multiplying the digital stream from each ADC 23 in the multipliers 16 by the weight factor W _mn (ϕ _i , θ _i ) from the ROM 17 and the summation in the digital adder 18. The radiation pattern for the i-th beam has the form

Where

The number of rays K is determined by the desired viewing area in the elevation plane and the width of one beam. The beams of the receiving multipath beam have a needle shape, are located in the elevation plane, while the directions of their maxima provide overlapping of the neighboring rays at the half power level. The width of the receiving radiation pattern corresponds to the angular size of the detection zone in the elevation plane.

The generated samples K of the receiving beams from the outputs of the formers 15 enter the interface 19, where they are converted into a serial form and transmitted in sequential codes to BOIKO 4, where objects, for example, moving ones, are measured in each of the adjacent pairs of formed receiving beams, and their distance and elevation coordinates corresponding to the elevation position of those receiving rays in which they were detected [8, p. 185-189 - Guide to radar / Ed. M.I. Skolnik. M .: Technoserv, 2014. vol. 1].

Multipath in the elevation plane of the beam ensures accelerated viewing of space by simultaneously detecting objects and measuring their coordinates in a wide elevation viewing sector. While in the prototype, the measurement of the coordinates of the object is carried out in two stages: first, a fan beam in the receive and transmit mode is used, while a rough measurement of the coordinates of the object is performed, and one needle-shaped beam is additionally used to refine the coordinates. A two-stage search for a prototype takes a longer time than in the proposed method, due to the introduction of additional commands for installing the CAR beam, loading weights of beam formation, etc. The space review time in the prototype is the longer, the more objects whose coordinates must be clarified.

The use in the proposed method for measuring elevation coordinates of several rays makes it possible to use the equal-signal direction finding method, which provides a significant reduction in measurement error [2 - p. 91] compared with the maximum method used in the prototype.

The use of a CAR with N transceiver modules containing solid-state power amplifiers located in the immediate vicinity of the antenna elements provides a reduction in the losses of the transmitted and received signals by reducing the length of the connections with the antenna element. Improving the reliability of a multi-element CAR is achieved by slowly reducing the characteristics of the CAR during the failure of some of the transceiver modules.

The performance of the proposed method was tested on the layout of the device (Fig. 1). Tests showed the coincidence of the obtained characteristics with the calculated ones.

Claims (1)

A space survey method, including sequential processing of data in discrete time with reference to each azimuthal position of the radiation pattern, the space survey is carried out by a fan radiation pattern sequentially occupying M azimuth positions and a needle-shaped radiation pattern, both radiation patterns being formed by one antenna electronic beam control system, characterized in that for the formation of the transmitting and receiving radiation patterns using they use a multi-element digital antenna array, and in each azimuthal position of the radiation pattern in the transmission mode, when generating a fan transmitting radiation pattern in the elevated plane, the probing signal is amplified in a solid-state power amplifier built into each transceiver channel of the digital antenna array and transmit it through a connecting circuit of minimum length to the antenna element connected to this channel, in the reception mode the reflected signals received from the output of each antenna ment, represent in the form of digital readings, from which, by weighted summation, a receiving multi-beam radiation pattern in the elevation plane is formed, each beam of which is needle-shaped, with adjacent rays overlapping at half power level, and the width of the receiving and transmitting radiation patterns corresponds to the angular size of the zone detection in the elevation plane, perform the detection of objects, measure their distance and elevation coordinates using a single-pulse method of signal processing each one of the neighboring pairs of receiving beams.

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