SU1723543A1 - Device for simulating of reflected radar signals - Google Patents

Abstract

This invention relates to radar. The aim of the invention is to increase the reliability of signal imitation. This is achieved by the fact that in a simulator containing a moving target formation unit 1, a high-frequency generator 2, a synchronous generator 3, a serially connected television unit 4, the first and second inputs of which are connected to the corresponding outputs of the synchronizing generator 3 and the corresponding inputs of the moving-forming unit 1 , the second modulator 5, the second input of which is connected to the output of the high-frequency generator 2, and the second attenuator 6. as well as series-connected linear mixer 11, the first input which is connected to the output of the high-frequency generator 2, the first modulator 12, the second input of which is connected to the first output of the moving target formation unit, and the first attenuator 13, is added an adder 7, whose inputs are connected to the outputs of the first 13 and second 6 attenuators, and the output is the output of the device, serially connected block 8 of forming the law of motion of the target along the angular coordinate and synchronous-tracking drive 9. on the output shaft of which television unit 4 is installed, as well as generator 10 of frequencies, whose input connected to the second output of the moving chain formation unit, and the first and second outputs, respectively, to the second and third inputs of the linear mixer 11.7 Il. cl

Description

The invention relates to radar and can be used to simulate the reflected radar signals in radars with linear sector scanning of the antenna pattern and an indicator with a rectangular raster scan in coordinates distance-angle.

A simulated reflected radar signal simulator is known that makes it possible to simulate the polarization properties of passive radar interference. The simulator contains a generator of horizontally polarized noise, two band-pass filters with variable bandwidth, an adder, a circular waveguide and a horn transmitter.

The disadvantage of this simulator is the low accuracy of the formation of signals of local objects due to the impossibility of forming the spatial structure of signals of local objects, which is close to real, since continuous noise voltage generators are used. Such an simulator will create a range - a corner illumination over the entire range, on the indicator of a type of radar, similar to the illumination from active noise.

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Also known is a simulated radar signal simulator containing a radial scanner, a circular scanner whose inputs are connected to the outputs of a circular view indicator, a cathode ray tube, a moving slide, an optical system, a photoelectric converter, the output of which is connected to the first input of the modulator and to the input threshold elements, the outputs of which are connected to the first inputs of the functional converter, the second input of which is connected to the output of the radial scanner unit, the output of the block a functional transducer coupled to a second input of the modulator.

The disadvantage of this device is the low accuracy of the formation of signals of local objects in connection with the fact that the slide displays local objects whose contours are unchanged, i.e. there is no expansion of the spectrum of signals reflected from local objects due to fluctuations of the reflecting surface of local objects.

Closest to the invention is a simulator selected for the prototype and containing a moving target driver, a television unit, a clock generator, a high frequency generator, a linear modulator, a linear mixer, a break modulator, a bandpass filter, the first and second controlled attenuators, a switch interference, pulse shaper of random duration.

In this simulator of the reflected signals, the driver of the moving targets and the television unit are simultaneously triggered by the signals of the synchronizing generator. The signals of the moving target simulator are fed directly to one of the inputs of the linear mixer. The signals from the television unit are simultaneously supplied to the inputs of a pulse shaper of random duration and a linear modulator. From one of the outputs of the pulse shaper of random duration, the pulses go to the driver of moving targets, and from the other output to the input of the break modulator. The signal inputs of the break modulator and the linear modulator from the high-frequency generator are supplied with radio signals of the type of sinusoidal oscillations. At the output of the pause modulator, a sequence of radio pulses is formed with a random duration and constant amplitude, and at the output of the linear modulator, a high-frequency signal with a variable modulation depth depending on the amplitude of the television modulator.

signal. The set of signals taken from the outputs of the first and second controlled attenuators and fed to the inputs of the linear mixer forms an interfering

background from local objects in the high-frequency range,

The disadvantage of this reflection simulator is the low accuracy of the formation of the signals reflected

0 from local objects due to the impossibility of changing the structure of signals reflected from local objects when the angular coordinates of the simulated target change, due to the absence of a shift in the frequency spectrum

5, a signal reflected from a target moving with a certain radial velocity relative to the spectrum of signals reflected from local objects, and also due to the absence of expansion of the spectrum of signals reflected from local objects due to the fluctuation of the reflecting surface of local objects.

The aim of the invention is to increase the reliability of signal imitation.

5 This is achieved by the fact that the unit of forming the law of motion of the target along the angular coordinate and the synchronous follower are additionally introduced into the proposed device.

0 a drive, on the output shaft of which a television unit is mounted, a frequency generator, the input of which is connected to the second output of the moving target formation unit, and the first and second outputs, respectively, to

5 by the second and third inputs of the linear mixer, as well as the adder, the inputs of which are connected to the outputs of the first and second attenuators, and the output is the output of the device.

0 Figure 1 presents the structural scheme of the simulator; Fig. 2 is a block diagram of a moving target formation unit; FIGS. 3 and 4 are a block diagram of a unit for forming the law of motion of an angular target.

5 coordinate and timing diagrams, which are related to his work, respectively; figure 5 - structural diagram of the frequency generator; figure 6 - structural diagram of the linear mixer.

0 A device for simulating reflected radar signals contains a unit 1 for generating moving targets, a high-frequency generator 2 connected in series to a television unit 3,

5 second modulator 4, the second input of which is connected to the output of the high-frequency generator 2, and the second attenuator 5, serially connected linear mixer 6, the first input of which is connected to the output of the high-frequency generator 2, the first modulator 7, the second input of which is connected to the first input of the unit forming the moving targets, and the first attenuator 8, as well as the synchronization generator 9, the first and second outputs of which are connected to the corresponding inputs of the formation of the moving targets and the television unit, are sequentially connected These block 10 form the law of motion of the target on the angular coordinate and synchronous-follower drive 11, on the output shaft of which television unit 4 is installed, a frequency generator 12 whose input is connected to the second output of the unit for forming moving targets, and the first and second outputs are respectively the second and third inputs of the linear mixer, as well as the adder 13, the inputs of which are connected to the outputs of the first 8 and second 5 attenuators, and the output is the output of the device.

The forming unit of the moving targets 1 can be made in the form shown in Fig.2. It contains a source 14 of a constant voltage, the output of which is connected to the input of the integrator 15 and the input of a frequency generator. The output of the integrator 15 is connected to the control input of fantastic 16, the start input of which is connected to the second output of the clock generator 3, and the output through the blocking generator 17 to the input of the modulator 20, the second input of which is connected to the output of the envelope shaping circuit pack 19, the input which through the delay circuit 18 is connected to the second output of the clock generator.

The block of formation of the law of motion along the angular coordinate can be made in the form shown in FIG. It includes series-connected time control unit 21 and a diode approximator 22. Time setting unit 21 forms a linearly varying voltage and can be implemented as an integrator, to the input of which a constant voltage source is connected, and a diode approximator 22 approximates the required the law of variation of the angular coordinate of the target by straight sections.

Timing diagrams explaining the principle of operation of a shaper of the law of motion of a target along an angular coordinate are shown in Fig. 4, where the dotted line shows the approximated law of motion of a target along an angular coordinate.

The frequency generator 12 is made according to the scheme shown in figure 5. It contains the first generator 23, the second generator 24, the first mixer 25, the controlled generator 26, the second mixer 27, the second input

The second mixer is connected to the output of the first mixer 25, the second input of which is connected to the output of the second generator 24. The first input of the first mixer 25 is connected to the output of the first generator 23, the first input of the second mixer 27 to the output of the controlled generator 26, the input of which is connected to the second input block formation of moving targets. Output second

0 mixer 27 is connected to the second input of the linear mixer 6, and the output of the first generator 23 to the third input of the linear mixer 6.

Linear mixer 6 is made according to

5 to the diagram shown in FIG. It contains the first mixer 28, the second mixer 29, and the first input of the second mixer 29 is connected to the output of the first mixer 28, the second input of which is connected to the output

0 of the second mixer 27 of the frequency generator 12. The first input of the first mixer 28 is connected to the output of the high-frequency generator 2, the second input of the second mixer 29 is connected to the output of the first frequency generator 12, the output

5 of the second mixer 29 to the first input of the first modulator 7.

The simulator works as follows.

Signals of the synchronizer 9 form a burst of pulses simulating the signal reflected from the moving target in the moving target formation unit, and start the line and frame scan of the television unit 3, the driving signal 5 from the circuit goes to the second input of the first modulator 7, the first input of which is continuous oscillation at the frequency fB4 ± RDS of the output of the linear mixer 6. At the first input of the linear mixer 6, there is an oscillation from the output of the high-frequency generator 2 at the frequency fen, and at the second input - the oscillation at the frequency fi + Rdmax - 2RD from the output of the frequency generator 12, to the third input of the linear mixer 6 oscillates at the frequency f i from the second output of the frequency generator 12.

The frequency of the moving target signal generated at the output of the first modulator 7 differs from the frequency of the high-frequency generator 2 by the amount of the Doppler additive RD. The magnitude of the Doppler frequency addition Pd is formed in a generator of 12 frequencies, which is controlled by a voltage proportional to the radial velocity

5 of the simulated target, which is fed to the input of the frequency generator from the second output of the signal generating unit of the moving target. The block of formation of the law of motion of the target along the angular coordinate 10 forms a voltage proportional to the position of the target relative to the origin of this coordinate. This voltage is fed to the input of the synchronous-tracking drive 11, the output shaft of which will rotate in accordance with the law of variation of the angular coordinate of the target. On the output shaft of a synchronous-tracking drive, a television unit 3 (transmitting camera) is fixed, the lens of which is aimed at real local objects, or on their mock-ups arranged appropriately around television unit 3. The signal from the output of the television unit goes to the second modulator 4, the second input of which receives oscillations from the output of the high-frequency generator 2 at the frequency of HF. At the output of the second modulator 4, we receive a television signal transferred to the frequency fB4. This signal through the second attenuator 5, intended to adjust the intensity of the signals of local objects, is fed to the second input of the adder 13, to the first input of which, through the first attenuator 8, a signal of a moving target is received at the frequency fen ± Pd. At the output of the adder 13, we obtain the mixed signals of the moving target at the frequency fB4 ± Rd and local objects at the frequency fB4.

If the lens of a television unit is aimed at real local objects, then due to fluctuations of the television image with small movements of local objects, for example under the action of wind, the spectrum of the television signal expands, imitating the expansion of the spectrum of signals reflected from local objects.

The shaper of moving targets works as follows. A voltage proportional to the radial velocity of the target is generated by a constant voltage source 14 and supplied to the integrator 15 and to the control input of the 12 frequency generator. At the output of the integrator 15, we obtain a linearly varying voltage proportional to the current range to the target. This voltage is applied as a control to fadron 16, which is triggered by a pulse from the output of the clock generator 9, which determines the zero range.

The impulse is removed from the output of fadron, the duration of which is proportional to the distance to the target. By dropping this pulse, blocking generator 17 is triggered, which generates a target pulse in amplitude and duration. The pulse from the output of the blocking generator 17 in each repetition period is fed to the modulator 20,

An impulse that determines the time of passage of the radar antenna of the beginning of the scanning sector from the second output of the clock generator 9 enters the input of the delay circuit 18, where it is delayed by a time equal to the time of the angle from the beginning of the scanning sector to the direction of the target. A pulse from the output of delay circuit 18 triggers the envelope shaping circuit 19, which forms a pulse whose shape is determined by the shape of the radar antenna pattern. This impulse comes

5 to the second input of the modulator 20, at the output of which a burst of pulses is formed, moreover, the delay of each pulse relative to the zero-range pulse determines the range of the simulated signal, and

0 the delay of the entire pack relative to the origin of the angular coordinate is the value of the angular coordinate of the simulated target.

The television unit 3 is a transmitting camera and a scanning unit. A pulse is sent to the start of the horizontal sweep, which determines the origin of the range from the first output of the synchronous generator 9, and the triggering of the vertical sweep is initiated by the angular

0 coordinate from the second output of the sync generator.

The frequency generator 12 operates as follows. The first generator 23 generates a vibration frequency fi, the second

5, the oscillator 24 is an oscillation frequency of Rdmax, at the output of the first mixer 25 an oscillation with the frequency fi + Rdmax is formed. The controlled oscillator 26 forms an oscillation, the frequency of which f2 can vary from 0 to

0 2 Rdmax, depending on the voltage proportional to the radial velocity of the simulated target, entering the generator 26 from the source 14 of the constant voltage of the block forming 5 moving targets 1, the output of the second mixer 27 oscillates with a frequency f 1 + Rdmax - f2 .

Linear mixer works as follows. The first input of the first mixer 28 receives an oscillation with a frequency of fun from a high-frequency generator 2, and the second input receives oscillations with a frequency of fi + + RDmax - h from the output of the second mixer 27 of the frequency generator 12. At the output of the first

5, the mixer 28 forms an oscillation with a frequency fB4 + fi + Pdmax-f2, which is fed to the first input of the second mixer 29, to the second input of which oscillates at a frequency fi from the first generator 23 of the frequency generator 12, to the output of the mixer 29

The difference between these frequencies is highlighted. As a result, the oscillation frequency at the output of the linear mixer 6 can vary from fB4 - Rdmax to fen + Rdmax. This oscillation is fed to the first input of the first modulator 7.

In order to align the clock pulses at the outputs of the clock generator 9 in time with the beginnings of sweeps around the angle and range of the radar indicator for pairing the object with the radar, this generator must be common to the simulator and the radar station. In particular, a radar clock generator can be used as a synchro-generator in the simulator.

The time setting unit 21 forms a linearly varying voltage and can be implemented as an integrator, to the input of which a constant voltage source is connected. The moment of connection of this constant voltage will be the moment of the start of the time setting device 21.

It is possible to restore the initial state of the setting device 21 when the voltage at a certain level is reached at its output or after a certain time from the moment of its start.

A schematic of the time setting unit 21 (integrator) for the case of restoring the initial state upon voltage reaching a certain level at the output is shown in Fig. 7.

When all supply voltages (UBx + Un, Ui) are connected to this circuit, at the moment the simulator is turned on, a linear control voltage will be generated at its output. When this voltage reaches a certain level, the initial state of the circuit will be restored.

The integrator circuit 15 can be implemented in the same way.

The adder 13 can be implemented as a summing amplifier, which is a two stage with a total load. The television signal at the fB4 frequency arrives at the input of the first stage, and the signal at the frequency TV ± RD arrives at the input of the second stage.

On the total load, the sum of the two signals is allocated.

When the lens of the television unit 3 is directed towards real local objects, the structure of the signals of local objects changes in accordance with the law of changing the angular coordinate of the target. As a result of this change in position of the television unit on the screen

The radar image of the fluctuating simulated signal reflected from local objects is formed, changing its structure when the target moves against the background of local objects.

Claims (1)

Invention Formula A device for simulating reflected radar signals, comprising a moving target formation unit, a high-frequency generator, in series connected television unit, second modulator, the second input of which is connected to the output of the high-frequency generator, and the second attenuator, serially connected linear mixer, first input which is connected to the output of the high-frequency generator, the first modulator, the second input of which is connected to the first output of the moving target formation unit, and the first attenuator, as well as the synchronous generator, the first and second outputs of which are connected to the corresponding inputs of the moving target formation unit and the television unit, different that, in order to increase the reliability-imitation of signals, sequentially connected block of formation of the law of motion of a target along the angular coordinate and synchronous-next p Drive, on the output shaft of which is installed a television unit, a frequency generator, the input of which is connected to the second output of the moving target formation unit, and the first and second outputs, respectively, to the second and third inputs of the linear mixer, and also an adder, the inputs of which are connected to the outputs of the first and second attenuators, and the output is the output of the device. FIG. 3 FIG. five from 2 from 23