RU2412449C2 - Radar target simulator - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: before combat mission, simulator is calibrated. Signal received from scanning radar is attenuated by first attenuator before conversion into intermediate frequency and delay thereon, by appropriate magnitude that sets maximum signal at digital delay circuit input. Before inverse conversion of delayed signal into carrier frequency, it is attenuated by second attenuator by magnitude equal to difference between signal attenuation in radio line radar - target and the sum of signal attenuation in first attenuator and constant losses in simulator. To set attenuation of first attenuator in calibration, first attenuator output signal is detected, and digitised. Mismatching of digitised signal maximum is determined in each scanning cycle relative to tolerable level used by computer to adjust signal attenuation for mismatch decrease till it becomes lower than tolerance.

EFFECT: higher validity of radar target simulation.

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Description

The present invention relates to radar, in particular to simulators of the target signal, and can be used both to simulate target signals located in a fixed direction, and as part of a complex that simulates a multi-purpose range, Doppler frequency and angle of the scene for studying search processes, detection and tracking goals (goals).

A known simulator of a radar portrait of a real target [1], in which the radar signal received by the receiving antenna of the simulator, is amplified, delayed in a multi-tap microwave (microwave) delay line in the calculated range. The delayed signals are modulated in amplitude, shifted by simulated Doppler frequencies, added, emitted by the transmitting antenna of the simulator as a simulated signal (s) of the target.

The disadvantage of this device is the relatively low reliability of the simulation of the target signal due to the lack of matching the signal level from the receiving antenna of the simulator with the dynamic range of the amplifier and the delay device connected in series, while when scanning a scene with a radar antenna in the simulator, distortions of the simulated signal are possible. In addition, the preparation and testing of each radar is very difficult and time-consuming, associated with the need for high-precision certification of the antenna pattern of the radar being tested, the angular position of the simulated target relative to the radar axes, and calculating the current angles between the direction of the radar and the direction to the simulated target, according to which taking into account the DND certification, the level of the radar signal at the input of the receiving antenna of the simulator is calculated, the necessary attenuation of the signal in the simulator at the estimated delay of the target signal for each position D A radar checked then determined and set by signal attenuation at the input of the transmitting antenna simulator.

The closest in technical essence to the claimed target simulator is a simulator [2], adopted as a prototype. In this simulator, the radar signal is received by the receiving antenna of the simulator, shifted by an intermediate frequency, delayed by time by a calculated value, shifted by frequency by a calculated Doppler shift, amplitude-controlled in accordance with the distance from the radar to the simulated target and the simulator, the effective scattering area of the target and the angle between the direction of the simulated target and the direction of sight of the radar is transferred to the carrier and emitted by the transmitting antenna of the simulator. The signal is delayed at an intermediate frequency digitally using a digital radio frequency memory device.

The disadvantage of the device [2], as well as the device [1], is the relatively low reliability of the simulation of the target signal due to the lack of matching the level of the signal supplied to the mixer from the receiving antenna with the dynamic range of the series-connected mixer and the digital radio frequency memory circuit, while scanning The radar antenna prices in the simulator may distort the simulated signal due to receiver overload. It is also very difficult and time-consuming for similar reasons, the preparation and testing of each radar.

The aim of the invention is to increase the reliability of the simulation of the target signal when scanning the scene of the checked radar while reducing the complexity of preparing and conducting tests by automatically matching the signal level shifted to the intermediate frequency with the dynamic range of the digital radio frequency memory circuit, hereinafter referred to as the digital signal delay circuit, input fixed attenuation delayed at the intermediate frequency of the signal in accordance with the difference in the estimated attenuation signal simulator and the level of attenuation introduced between the receiving antenna and the mixer simulator for signal conditioning circuit with a dynamic range digital delay signal.

The goal is realized in that in a simulator containing an antenna, a first attenuator connected in series, a first mixer, a digital signal delay circuit, a second attenuator, a second mixer, a third valve, a frequency synthesizer connected in series, a power divider, the first and second outputs of which are through the first and the second valves are connected to the second (heterodyne) inputs of the first and second mixers, respectively, a computer, the first, second and third outputs of which are connected to the second (control) inputs of the first o and the second attenuator and the digital delay circuit of the signal, the clock generator connected to the third input of the digital delay circuit, the second input-output of the calculator is the interface input-output of the simulator, through which the calculated data of the parameters of the simulated target signal about the delay, Doppler shift, and attenuation of the signal in the simulator, characterized in that an antenna switch is inserted into it, the third input-output of which is connected to the input-output of the antenna, a detector connected in series, an analog-to-digital converter An indicator whose output is connected to the first input of the calculator, the output of the third valve is connected to the second input of the antenna switch, the first output of which is connected to the first input of the first attenuator, the output of the first attenuator is connected to the input of the detector, and the fourth output of the calculator is connected to the input of the frequency synthesizer.

The invention is illustrated by a further description and drawings of a simulator of the target signal:

Figure 1 shows the structure of the proposed simulator,

Figure 2 shows the algorithm settings of the simulator before testing the radar.

In figure 1, the following notation:

1 - Antenna (AU);

2 - Antenna switch (AP);

3 - First attenuator (At1);

4 - The first mixer (SM!);

5 - Scheme of digital signal delay (CZS);

6 - Detector (D);

7 - The first valve (B1);

8 - Clock Generator (GT);

9 - Analog-to-digital Converter (ADC);

10 - The second valve (B2);

11 - Power divider (DM);

12 - Frequency Synthesizer (MF);

13 - The third valve (B3);

14 - The second mixer (CM2);

15 - Second attenuator (At2);

16 - Calculator (WU).

In figure 1, the antenna 1 through a series-connected antenna switch 2, the first attenuator 3, the first mixer 4, the digital delay circuit 5, the second attenuator 15, the second mixer 14, the third valve 13 connected to the second input of the antenna switch 2, the frequency synthesizer 12 through a series-connected power divider 11 and a second valve 10 connected to the second (heterodyne) input of the second mixer 14, the output of the first attenuator 3 through a series-connected detector 6 and ADC 9 is connected to the first input of the calculator 16, the first the second, second, third and fourth outputs of which are connected to the second (control) inputs of the first 3 and second 15 attenuators, the digital delay circuit of the signal 5 and the input of the frequency synthesizer 12, respectively, the first output of the power divider 11 through the first valve 7 is connected to the second input of the first mixer 4, the clock generator 8 is connected to the third input of the digital delay circuit 5, the second input-output of the calculator 16 is the interface input-output of the simulator, through which the calculated data of the parameters of the simulated target signal Hold, Doppler shift and signal attenuation in the simulator.

As a digital delay circuit 5, the 1879ВМ3 module developed by the OJSC “Module” can be used, or it can be built according to the scheme [1, p. 171 fig. 6.21]. As controlled attenuators 3 and 15, the AD 6630 attenuator from Analog Device can be used. As the calculator 16 can be used personal computer type Pentium, supplemented by elements of interfacing with controlled elements. The remaining elements, including the frequency synthesizer 12, are widely used in radar and do not require explanation for implementation.

The target simulator shown in Fig. 1 operates in three successive modes: 1) receiving initial information about the radar and target parameters, presetting the simulator, 2) calibrating the level of the simulated signal, 3) combat operation.

становится меньше порога (поз.21 фиг.2). На этом заканчивается регулировка затухания первого аттенюатора 3, запоминается сигнал управления U_AT1 и находится по таблице соответствующее ему затухание N_AT1 (поз.22 фиг.2). Далее вычислителем 16 рассчитывается необходимое затухание сигнала на входе второго смесителяIn all modes, the work is initiated by the operator using the commands and source data coming to the second input-output of the calculator 16. The operation of the simulator in the first two modes occurs in accordance with the algorithm shown in figure 2. The following input data are entered into the simulator: radar antenna gain G _radar , range to the simulated target R _c0 , its radial velocity V _r , radar carrier frequency F _n and effective scattering area of the simulated target σ _c (pos. 17 of FIG. 2). Known certified data are: range from the tested radar to the simulator R _and , the signal attenuation in the digital delay circuit Δ ₀ , the gain of the transmit-receive antenna of the simulator G _and . In the first mode, the calculator 16 calculates from the obtained and known data: 1) the initial delay of the digital delay circuit signal τ ₀ , its rate of change dτ / dt, the Doppler signal shift f _d and enters the calculation results into the digital delay circuit 5 through its second input (pos. .18 Fig. 2), 2) the frequency of the local oscillator signal F _g and input it into the frequency synthesizer 12 (pos. 19 of Fig. 2), which ensures the transfer of the radar signal received by the simulator to the operating frequency of the digital delay circuit 5, 3) required signal attenuation N (R _c , R _i , G _u , G _radar , σ _c , F _n ) in the simulator and through W A different input-output transmits a message to the operator about the readiness for the second mode (calibration of the level of the simulated signal), and the antenna scan of the checked radar is turned on (pos. 20 of Fig. 2). The radar signal received by antenna 1 through a series-connected antenna switch 2 and the first attenuator 3 is fed to a detector 6, where it is detected, then digitized by an analog-to-digital converter 9 and fed to a calculator 16, where its maximum value U _{M is} recorded and at each scanning interval . According to the results of each scan, the calculator 16 determines ΔU = U _M -U _o - the deviation of the maximum value of U _M from the upper acceptable value of the signal U _o at the input of the digital delay circuit 5. The value ΔU is used to step-by-step refine the control signal of the first attenuator 3, in which

becomes less than the threshold (pos.21 figure 2). This ends the attenuation control of the first attenuator 3, the control signal U _AT1 is stored, and the attenuation N _AT1 corresponding to it is located in the table (item 22 of FIG. 2). Next, the calculator 16 calculates the necessary attenuation of the signal at the input of the second mixer

N _AT2 = N (R _c , R _u , G _u , G _radar , σ _c , F _n ) -Δ ₀ -N _AT1 , dB.

The value of N _AT2 is entered by the calculator 16 to the second (control) input of the second attenuator 15 and is stored (key 23 of figure 2). The transmitter 16 informs the operator about the end of the calibration and readiness for combat work (pos.24 figure 2). With the arrival at the second input-output of the calculator 16, the command to start combat operation, the calculator 16 on the third output allows the digital delay circuit 5 to work with the previously established initial data on the signal delay τ ₀ , speed dτ / dt and Doppler shift f _d . The delay sample of the output signal of the digital delay circuit is determined by the period of the signal arriving at its third input from the clock generator 8.

The combat work of the simulator is as follows. The signal of the radar under test is received by antenna 1, enters through the antenna switch 2 to the first attenuator 3, where it is attenuated by the value N _AT1 , dB, set during calibration. Next, the received signal using the first mixer 4 and the local oscillator signal coming from the frequency synthesizer 12 through the power divider 11 and the first valve 7 to the second input of the first mixer 4, is transferred to the operating frequency of the digital delay circuit 5. The signal from the output of the first mixer 4 is delayed by the digital circuit delays 5 and through the second attenuator 15 enters the first input of the second mixer 14. Earlier during calibration, attenuator 15 exhibited attenuation of the signal N _AT2 . The second mixer 14 transfers the delayed signal to the carrier frequency using the local oscillator signal supplied to the second input of the second mixer 14 from the power divider 11 through the second valve 10. The output signal of the second mixer 14 is connected through the third valve 13 and the antenna switch 2 to the antenna 1, emitted and is the output signal of a simulator of a radar target.

In the process, due to simulated target movement, its range relative to the radar changes, respectively, the required signal attenuation in the second attenuator 15 N _AT2 (N, N _AT1 , Δ ₀ ). The necessary calculations and refinement of the settings of the second attenuator 15 are performed by the calculator 16 during the entire combat work until an external command is received to end the combat work at the second input-output of the calculator 16.

The technical advantage of the proposed radar target simulator over the prototype is to increase the reliability of the target signal simulation when scanning the scene of the checked radar while reducing the complexity of preparing and conducting tests by automatically matching the level of the signal received from the radar shifted to an intermediate frequency with the dynamic range of the digital delay circuit and the absence of the need to reconfigure the signal attenuation in the simulator with changes in the position of the radar bottom in the entire working scanning range, reducing the time required to prepare the workplace when changing the checked radar.

Using the information presented in the application materials, the radar target simulator can be made according to the existing technology known in the radio industry, on the basis of well-known components and used in radar checks during bench tests.

Information sources

1. Yu.M. Perunov et al. Radio-electronic suppression of information channels of weapon control systems. M .: Radio engineering, 2003 (p.135 fig. 5.2, p.171 fig. 6.21).

2. US patent 5892479 dated 6.4.1999, Electromagnetic target generator.

Claims (1)

A radar target simulator comprising an antenna, a first attenuator connected in series, a first mixer, a digital signal delay circuit, a second attenuator, a second mixer, a third valve, a frequency synthesizer connected in series, a power divider, the first and second outputs of which are connected to the second through the first and second valves the inputs of the first and second mixers, respectively, and which are heterodyne, a computer, the first and second outputs of which are connected to the second inputs of the first and second attenuators, i by controlling controllers, the third output of the calculator is connected to the second input of the digital delay circuit of the signal, which is the control via which data on the signal delay, its speed and Doppler shift are input, a clock generator connected to the third input of the digital delay circuit, characterized in that an antenna switch, the third input-output of which is connected to the input-output of the antenna, a detector connected in series, an analog-to-digital converter (ADC), the output of which is connected to the first input of the calculator, the output of the third valve is connected to the second input of the antenna switch, the first output of which is connected to the first input of the first attenuator, the output of the first attenuator is connected to the input of the detector, the fourth output of the computer is connected to the input of the frequency synthesizer, which is the control, the second input-output of the computer is the interface input the output of the simulator, which controls the simulator and enters data on the parameters of the checked radar and the simulated target, used by the calculator to calculate and enter the digital delay circuit of the required signal delay, its change rate and Doppler shift, calculation and input of the required heterodyne signal frequency into the synthesizer to ensure the transfer of the radar signal received by the simulator to the working frequency of the digital delay circuit, in the calibration mode, the calculator determines on each scan cycle the deviation of the maximum signal digitized by the ADC from the upper allowable value by which it forms and stores a control signal for the duration of the combat operation I am the first attenuator to reduce the deviation to a value less than the threshold.

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