RU2696274C1 - Small-size multi-mode on-board radar system for equipping promising unmanned and helicopter systems - Google Patents

Abstract

FIELD: radar ranging and radio navigation.

SUBSTANCE: invention relates to radar ranging, in particular, to radar systems. Technical result is achieved due to integration of digital devices included in the system (frequency synthesizer, synchronizer, receiver, central computer with high efficiency, high-speed data transmission interfaces) into a single macro module, as well as the presence of four receiving channels with difference radiation patterns in the inclined and azimuthal planes, total and compensated, using corresponding methods of monopulse direction finding, which increases accuracy and reliability of measurement of angular coordinates in azimuth and elevation angle. In the proposed system, probing signals are generated with different types of modulation, an inter-period spectrum expansion method is used, which enables to increase the range resolution using narrow-band signals with a known order in a pulse train and rapid tuning of frequencies from pulse to pulse.

EFFECT: design of a small-size multi-mode on-board radar system for equipping advanced unmanned and helicopter systems in order to perform monitoring of the earth's surface during search and rescue and special operations, as well as protection of coastal water area.

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Description

The invention relates to the field of radar and is intended to perform a wide range of tasks in the air-to-surface, air-to-air, meteo and low-altitude flight modes when used on aircraft, as well as in the security mode when used in stationary conditions.

Known radar systems (radar) for aircraft designed to detect, track objects, measure their coordinates, detect lightning fronts, detect and measure the height of ground obstacles and perform other functions.

For example, a dual-band monopulse radar with integrated control, application No. 2001104500 dated 02.20.2001. The radar contains an antenna with a range sum-difference device and auxiliary antennas, two transceiver paths. The problems of monopulse direction finding were solved when working in two ranges. However, the radar has the following disadvantages: the receiving path is analog, low noise immunity and resolution in coordinates; multifunctionality is not provided.

In the radar protected by patent WO 2010090564, a high resolution in coordinates has been achieved when operating in two ranges. The disadvantages include: low noise immunity, there is no single-pulse direction finding, multifunctionality is not provided.

Also known multifunctional radar station for aircraft (RU patent No. 2319173, IPC G01S 13/90), adopted as a prototype.

This radar performs the functions of detecting lightning fronts and cumulus clouds, surveying the earth's surface, detecting and measuring the height of ground obstacles when flying at low altitudes. The measurement function with a given accuracy of the height of ground obstacles is provided by narrowing the antenna beam in the elevation plane at the reception. This is achieved by the fact that in the slot antenna, in addition to the summary diagram, a difference diagram is formed in the elevation plane.

To accomplish the task of beam narrowing in the elevation plane of the total diagram, a difference diagram signal is used. For this purpose, a narrowing device is introduced into the digital signal processor, including a switch, a first memory device (U∑), a second memory device (UΔ), a difference device, the first and second multiplication device .

This radar has the following disadvantages: there is no monopulse direction finding in azimuth, low noise immunity along the mirror channel, there is no high resolution in coordinates, the frequency synthesizer is analog, which does not allow increasing the functions.

Given the current requirements for the implemented functions of the radar systems of aircraft, to increase the resolution, accuracy and reliability of solving problems with severe restrictions on the dimensions of the equipment, the objective of the invention is to create a small multi-mode onboard radar system.

The technical result from the use of the invention lies in the possibility of solving the problems of the prototype, and the following functions and properties are additionally implemented:

1) the use of different frequency ranges allows, using the features of the propagation and reflection of radio signals in different environments, integrally to obtain higher characteristics in range, accuracy, resolution in simple and complex interference and weather conditions, as well as to ensure the detection and observation of objects hidden by plant or other radiotransparent cover for used frequency ranges;

2) mapping with a real beam and aperture synthesis;

3) information support for low-altitude flight with the formation of a profile (vertical and horizontal) and quasi-three-dimensional radar images of the earth's surface and objects;

4) selection of moving objects;

5) determination of zones of increased turbulence and low-altitude "wind shears";

6) review, detection and tracking of air targets;

7) determination of the fact of violation of the boundaries of the protected zone.

The solution to this problem is achieved by the fact that the proposed radar (see Fig. 1) contains an antenna module (1) containing a slotted waveguide antenna array (VCHAR) (2), a drive (3) a four-channel microwave receiver (microwave receiver) with the first frequency transfer (4) and a circulator (5), a four-channel IF receiver with a second frequency transfer (6), a transmitter (7), a digital synthesizer of frequency and control clock signals (SCH) (8), an on-board digital computer (BCM) (9) , and a strapdown inertial navigation system (11), while the computer with holds a four-channel digital receiver (DSPM) (10), which has four analog-to-digital converters (ADCs), a programmable logic integrated circuit (FPGA) for information processing, control and input-output, while the first inputs of the ADC are connected to the corresponding outputs of the IF receiver in four receiving channels - total, differential in slope, differential in azimuth and compensation - at an intermediate frequency, the ADC outputs are connected to the FPGA of information processing, control and input-output, which, in turn, by means of high the low-speed interface (PCI-Express 8x) is connected to the on-board digital computer (BTsVM), the first output of the frequency response is connected to the input of the transmitter, the second output is to the input of the microwave receiver, the third output is to the second input of the ADC, the first output of the frequency response is connected to the digital FPGA the receiver and with the digital computer, the second output is with the DPCM, the third output is with the IF receiver, the fourth output is with the input of the microwave receiver, the fifth output is with the input of the PS VCHAR, the sixth output is with the input of the transmitter, and the input of the frequency response is with the digital computer through communication channel RS-485, output of platformless inertial system The system is connected to the computer via another RS-485 port.

The claimed invention is illustrated by figures.

In FIG. 1 presents a diagram of the proposed radar, where indicated:

1. Antenna module;

2. Waveguide-slot antenna array (VCHAR);

3. Antenna drive;

4. microwave receiver;

5. The circulator;

6. IF receiver;

7. Transmitter;

8. A synthesizer of frequencies and clock signals (SES);

9. BTsVM:

10. Digital receiver (DPC);

11. The strapdown inertial navigation system (SINS); RS-485 - information exchange channel;

System output - high speed interface.

In FIG. 2 shows a block diagram of a digital receiver, where are indicated:

12. ADC1 of the total channel ∑;

13. ADC2 of the difference channel by the slope Δн;

14. ADC3 of the difference channel in azimuth Δa;

15. ADC4 compensation channel K;

16. Programmable logic integrated circuit (FPGA) information processing, control and input-output information;

In FIG. 3 shows a block diagram of a digital frequency synthesizer and control clock, where are indicated:

17. Programmable logic integrated circuit (FPGA) control;

18. Digital local oscillator;

19. Digital quadrature mixer;

20. Digital-to-analog converter (DAC);

21. The reference frequency generator;

22. The mixer;

23. The switch.

In FIG. 4 shows a diagram of the implementation of the detailed resolution mode.

The construction of the proposed small multi-mode airborne radar system is based on the use of modern digital methods and devices for processing, receiving and transmitting information and software (software) in real time. This made it possible to create small-sized, highly integrated electronic modules that are combined with each other, with a digital computer and with SINS as part of the radar information exchange interfaces and have virtually no restrictions on their mutual placement. At the same time, during the operation of the radar, regular functional monitoring of the operability and adjustment of the product is carried out by supplying a pilot signal (PS), which is a simulation model of the sounding signal, to the inputs of the total and difference channels of the microwave receiver, through the VCHAR.

Proposed in accordance with FIG. 1 radar system consists of an antenna module (1) containing a VCHAR (2), a drive (3), a microwave receiver (4) and a circulator (5), an IF receiver (6), a transmitter (7), a frequency response system (8), a digital computer ( 9) with integrated DPCM (10) and SINS (11), interconnected by signal and control circuits, as well as high-speed interfaces (RS-485).

The sounding signal is produced through the total (∑) channel of the VCHAR (2), for which the output of the transmitter (7) is connected to the input of the circulator (5), and the “input-output” of the circulator (5) is connected to the total channel of the VChAR (2).

The reception of reflected sounding signals is carried out using the antenna module (1) through the VCHAR (2) in total (∑), difference in slope (Δн), difference in azimuth (Δа) and compensation (K) channels. To transmit the received VCHAR (2) signal through the total channel (∑), the output of the circulator (5) is connected to the first input of the microwave receiver (4). To transmit the received signal over the channel with a slope difference (Δн), the second output of the VCHAR (2) is connected to the second input of the microwave receiver (4). To transmit the received signal over the differential azimuth channel (Δа), the third output of the VCHAR (2) is connected to the third input of the microwave receiver (4). To transmit the received signal through the compensation channel (K), the fourth VCHAR output (2) is connected to the fourth input of the microwave receiver (4). The outputs of the corresponding channels of the microwave receivers (4) at the first intermediate frequency are connected to the corresponding inputs of the IF receiver. The outputs of the corresponding channels at the second intermediate frequency of the IF receiver (6) are connected to the inputs of ADC1 (12), ADC2 (13), ADC3 (14), ADC4 (15) of the digital receiver (10), the structure of which is shown in Fig. 2. In the digital receiver (10), the “digitized” signals of the receive channels ∑, Δн, Δa, and K from the outputs of ADC1 (12), ADC2 (13), ADC3 (14), ADC4 (15) respectively arrive at the first, second, third, and fourth FPGA inputs for information processing, control, and input-output (16), where digital heterodyning, quadrature demodulation of signals with linear frequency modulation (LFM), filtering and compensation of phase changes of the received signal due to carrier movement are performed. To exchange data from a digital receiver (10), the input-output FPGA (16) is connected to the system bus of the computer (9).

The generation of the signals of the clock interval and sampling frequency used in the digital receiver (10) and the digital computer (9) is performed in the frequency response system (8) shown in FIG. 3, the first output of which is connected to the FPGA input of information processing, control and input of the output (16) of the digital receiver (10) and the digital computer (9), and the second output is connected to the second control inputs of the ADC1 (12), ADC2 (13), ADC3 ( 14), ADC4 (15) of the digital receiver (10).

To transmit the frequency signal of the local oscillator frequency converter, the third output of the frequency response (8) is connected to the fifth input of the frequency converter receiver (6).

To transmit the frequency signal of the local oscillator, the fourth output of the frequency response (8) is connected to the fifth input of the microwave receiver (4).

To transmit the pilot signal, the fifth output of the frequency response system (8) is connected to the VCHAR

To transmit the probe signal at the appropriate carrier frequency, the sixth SCH terminal (8) is connected to the input of the transmitter (7).

The frequency response (8) is controlled from the digital computer (9) via the RS-485 channel via the FPGA control (17), the output signals of which are fed to the digital quadrature mixer (19) and the reference frequency generator (21).

For the first frequency conversion of the generated carrier signal from the second output of the reference frequency generator (21), the signal of the first local oscillator through the input and subsequent output of the digital local oscillator (18) is fed to the first input of the digital quadrature mixer (19).

To generate a carrier frequency signal with complex modulation laws and operational “pulse-to-pulse tuning”, the “modulation” component of this signal via the internal bus from the first FPGA output (17) is fed to the second input of the digital quadrature mixer (19), from the output of which the generated signal digitally fed to the input of the digital-to-analog converter (DAC) (20), where it is converted into an analog signal and fed to the mixer (22). The oscillator frequency signal is fed to the second input of the mixer (22) from the reference frequency generator (21). In the mixer (22), a carrier frequency signal is generated, which is fed to the input of the transmitter (7).

To increase the radar resolution in various modes when synthesizing an aperture, calculating the exact trajectory of the aircraft, the parameters necessary to process the received signals from information received from the SINS (11) via the RS-485 interface to a separate input of the computer (9) are calculated .

The proposed radar architecture and the construction of the described devices provide wide information capabilities, high resolution and accuracy due to the formation of complex broadband probing signals and subsequent preliminary, primary and secondary processing of the received signals, taking into account the destabilizing factors of carrier movement.

Below is an example of signal processing that implements the detailed resolution mode (DR), and shows the capabilities of the radar to use new highly efficient methods of signal processing.

In FIG. 4 shows a diagram of the implementation of the DR mode.

Radar signals are processed in three stages. At the first stage, preliminary processing is performed in a digital receiver (10). In this case:

- measurement of the maximum signal level;

- removal of the DC component in the signal;

digital heterodyning (compensation of phase changes of the received signal from count to count and from pulse to pulse due to carrier movement);

- demodulation of chirp signals.

At stage two, the primary signal processing on the digital computer is performed (9). In this case, a frequency-manipulated signal is converted, including:

- FFT (fast Fourier transform) in range;

- phase correction, compensating the dependence of the delay of the received signal on the distance;

- inverse FFT in range;

- sampling (correction of the phase of the signal to eliminate the dependence of the Doppler frequency on distance and changing the distance from pulse to pulse within the radar cycle, docking of fragments of the sample in the time domain);

- recording of samples (radio holograms) in memory.

At stage three, the secondary processing of the digital computer signals is performed (9). At the same time carried out:

- autofocus signals;

- Compression of signals in azimuth using FFT;

- phase correction of signal migration along range elements;

- inter-period spreading of the signal spectrum based on the accepted implementation of the packet at different carrier frequencies;

- range signal compression using FFT;

- incoherent summation of signals over several carrier frequencies to reduce the speckle effect;

- formation of a radar image (RLI) (compensation of amplitude modulation caused by the automatic gain control of the signal (ARUS), the influence of the antenna pattern (BOTTOM) in azimuth and slope, as well as by changing the signal level from distance, calculating the screen coordinates of the radar points, forming an array amplitudes in indicator format, conversion of the dynamic range of signal amplitudes to the dynamic range of radar data, information output via a high-speed interface.

The synchronization of the radar and information exchange of signal processing processors is carried out under the control of the real-time operating system (OS RV) BTsVM (9), which also performs:

- formation of a viewing zone;

- module management;

- receiving information from the navigation system via RS-485;

- calculation of the trajectory of the aircraft;

- calculation of the parameters necessary for processing the received signals.

Claims (2)

Small-sized multi-mode airborne radar system for equipping advanced unmanned and helicopter systems, comprising an antenna module, an IF receiver, a transmitter and an on-board digital computer (BCM), characterized in that it contains an antenna module containing a slotted waveguide antenna array (VCHAR), a drive, a microwave receiver and a circulator, a four-channel IF receiver, a digital synthesizer of frequency and control clock signals (SCH), a digital receiver connected to the computer system bus, and a strapdown inertial system that is connected to the digital computer, while for the emission of the probing signal, the output of the transmitter is connected through the circulator to the total channel of the VCHAR, and for receiving the reflected signal through the total channel of the VCHAR is connected through the controller with the total channel of the microwave receiver, for receiving through the differential channels on the slope and azimuth of the VChAR is connected to the corresponding differential channels of the microwave receiver and for receiving on the compensation channel of the VCHAR is connected to the compensation channel of the microwave receiver, the outputs of which at the intermediate frequency are connected respectively to four inputs of the IF receiver, the outputs of which at an intermediate frequency are connected respectively to the four inputs of a digital receiver containing a four-channel analog-to-digital converter (A CPU), programmable logic integrated circuit (FPGA) for information processing, control and input-output, while the outputs of the four-channel ADC are connected to the four inputs of the FPGA, and the "input-output" of the FPGA is connected to the high-speed system bus of the computer, while the sixth output the carrier frequency signal output is connected to the transmitter input, the fifth output is the pilot signal output connected to the VCHAR input, the fourth output is the local oscillator signal output is connected to the microwave receiver input, the third output is the IF local oscillator signal output is connected to the IF receiver, second the first output is the output of the signal of the sampling frequency connected to the control input of the four-channel ADC of the digital receiver, the first output is the output of the signals of the clock interval is connected to the control input of the FPGA of the digital receiver and the digital computer; via the RS-485 interface; The high-speed bi-directional output of the computer is the output of the system.

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