CN111812604A

CN111812604A - Full-coherent millimeter wave target simulator with composite seeker

Info

Publication number: CN111812604A
Application number: CN202010703599.0A
Authority: CN
Inventors: 但波; 刘瑜; 康家方; 高山; 翟龙军; 谭大宁; 王旭坤; 张军涛
Original assignee: Naval Aeronautical University
Current assignee: Naval Aeronautical University
Priority date: 2020-07-21
Filing date: 2020-07-21
Publication date: 2020-10-23
Anticipated expiration: 2040-07-21
Also published as: CN111812604B

Abstract

The invention relates to a full-coherent millimeter wave target simulator with a composite seeker. The simulator includes: the system comprises a reference signal source selection module, a frequency synthesis module, a millimeter wave module, a bottom hardware control module and a main control computer module; the signal output end of the reference signal source selection module is connected with the signal input end of the frequency synthesis module; the signal output end of the frequency synthesis module is connected with the signal input end of the millimeter wave module; the frequency synthesis module and the millimeter wave module are in data interaction with the main control computer module through the bus. The simulator provided by the invention has the characteristics of high working frequency and wide frequency band, can better ensure the coherence of the output millimeter wave target characteristic signal and an external phase reference clock, and can also ensure better phase noise and stray performance. And on the premise of ensuring complete coherence of signals, the Ka-band signal with low phase noise, high frequency resolution and wide frequency band is generated, and simultaneously, target echo signals with different motion speeds can be simulated.

Description

Full-coherent millimeter wave target simulator with composite seeker

Technical Field

The invention relates to the field of millimeter wave seeker equipment, in particular to a full-coherent millimeter wave target simulator of a composite seeker.

Background

With the development of modern radar technology, the working frequency band of the radar is expanded from a meter wave band to a millimeter wave band, and the working system of the radar is also developed from a simple pulse system radar to a new system full coherent radar such as a pulse Doppler radar and a pulse compression radar. Because of the superiority of the full-coherent radar, the coherent radar has been widely applied to weapon systems of various motion platforms, and becomes an important means for reconnaissance and battle in modern war. Compared with other guide heads, the millimeter wave radar guide head has the following good performances:

because the wavelength is short, a narrow beam can be obtained, and therefore the resolution is high; the all-weather working capacity is better; the anti-interference capability is very strong; the millimeter wave radar is small in size, light in weight and low in power consumption, so that modularization is facilitated. The full-coherent radar utilizes Doppler information carried in target echoes to realize the separation of targets and clutter in a frequency domain, can detect the target echoes from a strong clutter background, and can accurately measure the speed.

Because the radar target simulator can realistically simulate complex electromagnetic environments in a battlefield, the radar target simulator is generally provided with an advanced radar target simulator for testing and evaluating a radar system. Currently, various radar target simulators are researched and manufactured by huge resources in many countries in the world.

A radar system simulation laboratory is established abroad from the seventies, and the simulation wave band covers all wave bands of a guidance system, including a centimeter wave simulator, a millimeter wave simulator, a laser simulator, an infrared photoelectric simulator, a GPS simulator, an inertial interrupt simulator and the like. There have been two hundred or more companies in the united states developing simulators with billions of dollars per year investment.

The digitalized radar target simulator of the KOR Electronics company in the United states adopts the latest computer, DSP technology and systematization module designs such as an advanced VME bus structure and the like, can simultaneously generate a large amount of vivid targets, clutter and interference echoes, and can provide radar echo signals in digital intermediate frequency and radio frequency forms. A PC (personal computer) based on a Pentium processor is adopted as a host of a radar target simulator of KOR company, and a graphical interface is adopted as software, so that the functions of setting and maintaining a clutter environment can be completed. The graphical interface allows the operator to conveniently define the radar echo environment using the targets, clutter, antenna orientation, etc. components in the tool library, and may allow user-defined input or modification of the data files saved to the library. The host computer can detect and control the radar environment simulation process at the same time. Because the target simulator adopts a VME bus structure, the problem of real-time interface with a complex radar system is solved by an industry standard, high-speed and modular solution. The structure also expands the compatibility of the system, enhances the performance of the system through the microprocessor and the DSP technology, and can flexibly expand the system according to the requirement.

A radar target simulator developed by Sensis corporation of America for AN/TPS long-distance warning radar consists of a Solaris Sparcv2.6 workstation and a group of radar simulator hardware equipment. The radar system can provide radio frequency signals containing targets, clutter and electronic countermeasure information for the radar in real time according to a preset radar environment so as to meet the requirements of radar engineering design verification and debugging. The target simulator can establish any radar environment in a laboratory, a factory, training and an outfield; 30 targets can be simulated according to user settings, and the targets can have the characteristics of flicker, fluctuation, different tracks and the like; parameters such as clutter areas, Doppler frequency shift, direction, fluctuation, space distribution and the like can be set to simulate meteorological clutter, ground clutter, sea clutter and interference; antennas are provided to realistically simulate real world scenarios.

A target simulator developed by Malibu Research in the United states and used for AN/TPQ-36 and AN/TPQ-37 forced cannon fire control radar consists of a computer and a hardware system of a radar signal simulator. The simulator can provide signals in the forms of digital video, intermediate frequency and radio frequency for debugging and testing of the radar; the antenna model includes various scanning techniques of electrical scanning and mechanical scanning; simulated radar echo environments include targets, noise, clutter (earth, sea, weather), electronic warfare, deceptive jamming, and the like; the method supports LFM/NLFM, PSK and other multi-waveform coding modes, the pulse width range of Frequency Modulated Continuous Wave (FMCW) is 0.1 us-300 s, the Pulse Repetition Frequency (PRF) range is 100 Hz-200K Hz, and the Doppler resolution is 1 Hz.

The HP company produces an X-band radar moving target Signal Simulator of a parallel Frequency Agile Signal Simulator (FASS) by using special equipment and patent products thereof, can output radio frequency signals of 9 GHz-11 GHz, and simultaneously generates target signals of three channels of sum, azimuth difference and pitch difference.

The typical Radar simulator simulation software is Radar Toolkit which is software developed by Camber company in America and used for simulation and emulation of nearly 20 Radar systems such as AWG-9, AW G-10 and the like, and provides modules such as a land environment, a marine environment, a meteorological environment, an irradiation mode, friend or foe identification and the like, and the simulated Radar effects comprise: radar height, gesture, distance decay, atmospheric attenuation and antenna pattern, the radar parameter that can simulate includes with signal processing effect: signal frequency, range, pulse width, transmit power, interference, etc. In 2001, Camber developed a target generator and a Radar simulator for Raytheon air stage-Off Radar by using Radar Toolkit, and the realization platform is Windows NT.

Many research reports on radar signal simulators are continuously reported from the last 90 years in China, and various types of radar simulators are developed by many units. In 1994, the electronic part adopts a single TMS320C25 to realize a high-precision fully programmable radar video echo simulator, and can simulate orthogonal band-limited noise, clutter and Doppler target echo signals of various frequencies in a video mode.

A general radar target simulator was developed by the north aviation and aviation sector 601 in 1999. The general radar target simulator adopts two high-stability frequency synthesis microwave signal sources as an echo signal carrier source and a clutter signal carrier source respectively, controls the pulse delay and the Doppler frequency shift of a video signal through a computer, and simulates different distances and relative speeds between a radar and a target. The simulator receives and transmits a shared antenna, and the antenna is arranged on a rotatable structure to detect the radar angle tracking capability.

The millimeter wave target simulator developed in 2000 by the electronic engineering system of China science mainly comprises: the main control computer, the target simulator, the radio frequency extension, the motion support structure, the flight turntable and the like can provide coherent millimeter wave radio frequency echo signals for the linear frequency modulation continuous wave system radar, the center frequency is 35GHz, the echo power has a 100dB dynamic range and a step size of 0.1dBm, but the millimeter wave radio frequency echo power is only suitable for the millimeter wave continuous wave system linear frequency modulation radar and is not suitable for the millimeter wave pulse system coherent radar.

The university of electronic technology has developed millimeter wave high resolution pulse radar signal simulator, and this simulator includes: the software modeling and hardware waveform generator can simulate the echo signal, clutter and noise of the radar system in various environments, can provide orthogonal video signals after coherent demodulation, and can be used as a debugging tool of a signal processing and display system. The simulator is a 3mm high-resolution pulse radar signal source which is firstly completed in China. The system has small noise in the machine, and I, Q has good consistency of two paths. The device can simulate echo signals, clutter and noise in various environments, can be used for debugging and trial use of a signal processor and a display system, and is essential equipment for radar performance detection.

The radar target and clutter simulator designed by the university of West's electronics science and technology adopts the waveform storage and replay technology, and can be used for debugging the monopulse tracking radar and testing the performance of the monopulse tracking radar. The target video echo signal generated by the device can move along the direction and the distance, and can be in the background of noise and clutter, and the device can also simulate the video echo signal of the radar in searching and tracking various working states, so as to complete the debugging of the whole process of searching, intercepting and tracking of the radar and the testing of the detection and tracking performance of the radar in the clutter environment.

In recent years, a series of synthetic signal generators have been developed in succession, with further improvements in technology, extending the frequency range up to 110GHz and increasing the broadband coaxial continuous coverage up to 40 GHz. Based on the existing microwave synthesis signal source of the company 41 of the electronic science and technology group of china, millimeter wave spread spectrum is carried out, and millimeter wave signal generators such as AV12411, AV12413 and the like are introduced.

However, these products can only work in a dot frequency mode, cannot generate radio frequency signals completely coherent with the radar, can only be regarded as standard millimeter wave signal sources, cannot simulate the intra-pulse modulation characteristics of the radar, and users can only set and output fixed frequency, which is far from meeting the requirements for testing the performance of the millimeter wave radar.

Therefore, it is a technical problem to be solved in the art to provide a millimeter wave target simulator capable of generating a radio frequency signal completely coherent to a radar and simulating an intra-pulse modulation characteristic of the radar so as to meet a requirement for testing performance of the millimeter wave radar.

Disclosure of Invention

The invention aims to provide a composite seeker holophase-coherent millimeter wave target simulator which can generate radio frequency signals completely coherent with radar and simulate the intra-pulse modulation characteristics of the radar so as to meet the requirement of testing the performance of the millimeter wave radar.

In order to achieve the purpose, the invention provides the following scheme:

a composite seeker holohedral millimeter wave target simulator, comprising: the system comprises a reference signal source selection module, a frequency synthesis module, a millimeter wave module, a bottom hardware control module and a main control computer module;

the signal output end of the reference signal source selection module is connected with the signal input end of the frequency synthesis module; the signal output end of the frequency synthesis module is connected with the signal input end of the millimeter wave module; the frequency synthesis module and the millimeter wave module are in data interaction with the main control computer module through a bus;

the reference signal source selection module is used for switching a working mode and selecting a reference signal; the working modes comprise a full-coherent working mode and a non-coherent working mode; the reference signals comprise coherent reference signals and non-coherent reference signals;

the frequency synthesis module is used for generating a millimeter local oscillator signal and a baseband signal and carrying out up-mixing on the millimeter local oscillator signal and the baseband signal to obtain a millimeter wave linear frequency modulation signal;

the millimeter wave module is used for generating a Ka-band radio frequency signal according to the millimeter wave linear frequency modulation signal and generating an output signal after pulse modulation is carried out on the Ka-band radio frequency signal;

the bottom hardware control module is used for controlling the power of the output signal;

the main control computer module is used for generating control data according to data input by a user and respectively sending the control data to the frequency synthesis module and the bottom hardware control module through buses; the control data includes: a frequency control command, a power attenuation control command, and a waveform modulation control command.

Preferably, the reference signal source selecting module includes: a selection switch and a reference signal power divider;

the selection switch is connected with the reference signal power divider; and the reference signal power divider is connected with the frequency synthesis module.

Preferably, the frequency synthesis module includes: the frequency synthesizer, the direct digital frequency synthesis chip, the frequency control circuit and the up-converter;

the signal input end of the frequency synthesizer and the signal input end of the direct digital frequency synthesis chip are both connected with the signal output end of the reference signal source selection module; the signal output end of the frequency synthesizer and the signal output end of the direct digital frequency synthesis chip are both connected with the signal input end of the up-converter; the signal output end of the up-converter is connected with the signal input end of the millimeter wave module; the frequency synthesizer and the direct digital frequency synthesis chip are in data interaction with the frequency control circuit;

the frequency synthesizer is used for generating a millimeter wave dot frequency signal according to the reference signal; the direct digital frequency synthesis chip is used for generating a baseband signal according to the reference signal; the baseband signals comprise chirp signals and Doppler frequency spectrum signals;

the frequency control circuit is used for controlling the frequency synthesizer and the direct digital frequency synthesis chip to generate a specific millimeter wave dot frequency signal and a specific baseband signal;

the up-converter is used for carrying out up-mixing on the millimeter local oscillator signal and the baseband signal to obtain a millimeter wave linear frequency modulation signal.

Preferably, the millimeter wave module includes: a frequency multiplier, an amplifier, an attenuation unit and a modulator;

the signal input end of the frequency multiplier is connected with the signal output end of the frequency synthesis module; the signal output end of the frequency multiplier is connected with the signal input end of the amplifier; the signal input end of the amplifier is connected with the signal input end of the attenuation unit; the signal output end of the attenuation unit is connected with the signal input end of the modulator; the signal output end of the modulator is connected with the radio frequency output end;

the frequency multiplier is used for generating a Ka-band radio-frequency signal according to the millimeter wave linear frequency modulation signal; the amplifier is used for amplifying the Ka-band radio-frequency signal to obtain an amplified Ka-band radio-frequency signal; the attenuation unit is used for adjusting the power of the amplified Ka-band radio-frequency signal to a preset range; the modulator is used for carrying out pulse modulation on the amplified Ka-band radio-frequency signal after power adjustment to generate an output signal.

Preferably, the bottom hardware control module includes: a power control unit and a modulation waveform generation unit;

the power control unit and the modulation waveform generating unit are both connected with the millimeter wave module;

the power control unit is used for controlling the output power of the output signal; the modulation waveform generating unit is used for providing synchronous pulses and generating pulse modulation signals.

Preferably, the power control unit includes: a scaling attenuation control circuit and a power attenuation control circuit;

the calibration attenuation control circuit and the power attenuation control circuit are both connected with the millimeter wave module; the scaling attenuation control circuit and the power attenuation control circuit are in data interaction with the main control computer module through a bus.

Preferably, the master control computer module includes: an input unit and a PC104 embedded computer;

the input unit is connected with the PC104 embedded computer;

the input unit is used for inputting working parameters; the working parameters comprise: a mode of operation, a power attenuation value and a pulse delay value; and the PC104 embedded computer is used for generating control data according to the working parameters.

Preferably, the method further comprises the following steps: a remote control interface module;

the remote control interface module performs data interaction with the main control computer module;

the remote control interface module is used for realizing information interaction and signal remote transmission between the radar and the composite seeker holohedral millimeter wave target simulator and between the remote control equipment and the composite seeker holohedral millimeter wave target simulator.

Preferably, the method further comprises the following steps: the system comprises a power supply module and a self-checking module;

the power supply module is used for providing electric energy for the composite seeker holohedral millimeter wave target simulator; and the self-checking module is used for detecting whether the communication among the modules is normal or not.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

1. on the premise of ensuring complete coherence of signals, Ka-band signals with low phase noise, high frequency resolution and wide frequency band are generated;

2. target echo signals with different movement speeds can be simulated, corresponding Doppler frequency shift output is superposed, and the distance changes along with the movement speed;

3. linear frequency modulation signals in the pulse can be simulated and generated;

4. three target echo signals can be generated in a radio frequency channel in an analog mode, and parameters such as pulse delay, pulse width, repetition frequency and movement speed can be set respectively;

5. the method can simulate a trailing interference signal, a continuous wave interference signal and a same frequency asynchronous interference signal.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

Fig. 1 is a schematic structural diagram of a composite seeker holohedral millimeter wave target simulator provided by the invention;

FIG. 2 is a schematic diagram of a power scaling control provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of power attenuation control provided by an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a remote control interface module according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a front panel of a composite seeker holohedral millimeter wave target simulator according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of a rear panel of a composite seeker holohedral millimeter wave target simulator according to an embodiment of the present invention.

Description of the symbols:

1 a reference signal source selection module, 1-1 a selection switch, 1-2 a reference signal power divider, 2-frequency synthesis module, 2-1 a frequency synthesizer, 2-2 a direct digital frequency synthesis chip (DDS), 2-3 a frequency control circuit, 2-4 an up-converter, 3 a millimeter wave module, 3-1 an amplifier, 3-2 a scaling attenuator, 3-3 a directional coupler, 3-4 an attenuator, 3-5 a modulator, 4 a bottom hardware control module, 4-1 a scaling attenuation control circuit, 4-2 a power attenuation control circuit, 4-3 a modulation waveform generation circuit, 5 a main control computer module, 5-1 an input unit, 5-2 a PC104 embedded computer, 5-3 a display screen, 6a remote control interface module, 7 power module, 8 self-checking module, 9 bus.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a composite seeker holophase-coherent millimeter wave target simulator, which can generate radio frequency signals completely coherent with radar, simulate the intra-pulse modulation characteristics of the radar and further meet the requirement of testing the performance of the millimeter wave radar.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Fig. 1 is a schematic structural diagram of a composite seeker holohedral millimeter wave target simulator provided by the present invention, and as shown in fig. 1, a composite seeker holohedral millimeter wave target simulator includes: the device comprises a reference signal source selection module 1, a frequency synthesis module 2, a millimeter wave module 3, a bottom hardware control module 4 and a main control computer module 5.

And the signal output end of the reference signal source selection module 1 is connected with the signal input end of the frequency synthesis module 2. And the signal output end of the frequency synthesis module 2 is connected with the signal input end of the millimeter wave module 3. The frequency synthesis module 2 and the millimeter wave module 3 are in data interaction with the main control computer module 5 through the bus 9.

The reference signal source selection module 1 is used for switching the working mode and selecting the reference signal. The operating modes include a fully coherent operating mode and a non-coherent operating mode. The reference signals include coherent reference signals and non-coherent reference signals.

The frequency synthesis module 2 is configured to generate a millimeter local oscillator signal and a baseband signal, and perform up-mixing on the millimeter local oscillator signal and the baseband signal to obtain a millimeter wave chirp signal.

The millimeter wave module 3 is used for generating a Ka-band radio frequency signal according to the millimeter wave chirp signal, and is used for generating an output signal after performing pulse modulation on the Ka-band radio frequency signal.

The bottom hardware control module 4 is used to control the power of the output signal.

The main control computer module 5 is used for generating control data according to data input by a user and sending the control data to the frequency synthesis module 2 and the bottom hardware control module 4 through the bus 9. The control data includes: a frequency control command, a power attenuation control command, and a waveform modulation control command.

The bus 9 used in the present invention is preferably an ISA bus, but is not limited thereto.

Preferably, the reference signal source selection module 1 includes: a selection switch 1-1 and a reference signal power divider 1-2.

The selection switch 1-1 is connected with the reference signal power divider 1-2. The reference signal power divider 1-2 is connected with the frequency synthesis module 2.

The reference signal power divider 1-2 is equivalent to change the single reference signal selected by the selection switch 1-1 into two identical signals and send the two identical signals to the frequency synthesis module 2.

In the invention, the reference signal source module realizes the switching of the full-coherent and non-coherent working modes mainly through the selection switch 1-1. When the simulator provided by the invention selects the 100MHz coherent reference signal provided by the detected coherent radar as the reference clock of the simulator, the simulator works in a coherent mode and can provide a signal which is completely coherent with the detected radar. When the 100MHz non-coherent reference signal inside the simulator is selected as the simulator reference clock, the simulator operates in a non-coherent mode.

Preferably, the frequency synthesis module 2 comprises: a frequency Synthesizer 2-1, a Direct Digital synthesis chip 2-2(DDS chip), a frequency control circuit 2-3 and an up-converter 2-4. Among them, the frequency synthesizer 2-1 is preferably the frequency synthesizer 2-1 of the DDS excited PLL.

The signal input end of the frequency synthesizer 2-1 and the signal input end of the direct digital frequency synthesis chip 2-2 are both connected with the signal output end of the reference signal source selection module 1. The signal output end of the frequency synthesizer 2-1 and the signal output end of the direct digital frequency synthesis chip 2-2 are connected with the signal input end of the up-converter 2-4. The signal output end of the up-converter 2-4 is connected with the signal input end of the millimeter wave module 3. The frequency synthesizer 2-1 and the direct digital frequency synthesis chip 2-2 are in data interaction with the frequency control circuit 2-3.

The frequency synthesizer 2-1 is used for generating a millimeter wave dot frequency signal according to the reference signal. The direct digital frequency synthesizing chip 2-2 is used for generating a baseband signal from a reference signal. The baseband signal includes a chirp signal and a doppler spectrum signal.

The frequency control circuit 2-3 is used for controlling the frequency synthesizer 2-1 and the direct digital frequency synthesis chip 2-2 to generate a specific millimeter wave dot frequency signal and a specific baseband signal.

The up-converters 2 to 4 are used for carrying out up-mixing on the millimeter local oscillator signals and the baseband signals to obtain millimeter wave linear frequency modulation signals.

The frequency synthesizer 2-1 of the DDS excited PLL in the frequency synthesis module 2 only generates millimeter wave dot frequency signals, and the frequency of the millimeter wave dot frequency signals is millimeter wave high frequency signals and is also called local oscillation signals. Another single DDS chip mainly generates a chirp signal and a doppler frequency, which is an intermediate frequency signal, also called a baseband signal. The up-converter 2-4 is used for up-mixing the millimeter wave local oscillation signal generated by the frequency synthesizer 2-1 of the DDS excited PLL and the baseband signal generated by the DDS chip, which is equivalent to modulating the baseband signal to the frequency of the local oscillation signal. For example: the frequency synthesizer 2-1 of the DDS excitation PLL generates a millimeter wave dot frequency signal with the frequency of 35GHz, the DDS chip generates a linear frequency modulation signal with the bandwidth of 20MHz, the frequency is 0MHz-20MHz, and then the millimeter wave linear frequency modulation signal is a linear frequency modulation signal with the center frequency of 35GHz and the bandwidth of 20MHz after up-mixing is carried out by the up-converter 2-4, and the frequency range is 34990MHz-35010 MHz.

Because both the DDS and the frequency synthesizer 2-1 in the frequency synthesis module 2 require a reference signal as a reference source, if the reference signal selects a 100MHz coherent signal from the radar to be detected, a fixed phase relationship exists between the signal generated by the frequency synthesizer 2-1 and the radar signal to be detected, which is a coherent operating mode. If the reference signal selects a non-coherent 100MHz signal from the frequency selection module, the signal generated by the frequency synthesizer 2-1 has no fixed phase relation with the radar signal to be detected, i.e. the non-coherent working mode.

Because the simulator provided by the invention is mainly used for measuring the performance of the coherent radar, and the chirp signals and the Doppler frequency are common signal forms of the coherent radar, signals such as chirp signals, Doppler frequency signals and the like need to be generated to simulate coherent radar signals.

Preferably, the millimeter wave module 3 includes: a frequency multiplier, an amplifier 3-1, an attenuation unit and a modulator 3-5.

The signal input end of the frequency multiplier is connected with the signal output end of the frequency synthesis module 2. The signal output end of the frequency multiplier is connected with the signal input end of the amplifier 3-1. The signal input of the amplifier 3-1 is connected to the signal input of the attenuation unit. The signal output of the attenuation unit is connected to the signal input of the modulator 3-5. The signal output ends of the modulators 3-5 are connected with the radio frequency output end.

The frequency multiplier is used for generating Ka-band radio-frequency signals according to the millimeter wave linear frequency modulation signals. The amplifier 3-1 is used for amplifying the Ka-band radio-frequency signal to obtain an amplified Ka-band radio-frequency signal. The attenuation unit is used for adjusting the power of the amplified Ka-band radio-frequency signal to a preset range. The modulator 3-5 is used for carrying out pulse modulation on the amplified Ka-band radio-frequency signal after power adjustment to generate an output signal.

The attenuation unit comprises a scaling attenuator 3-2, a directional coupler 3-3 and an attenuator 3-4.

The millimeter wave module 3 mainly uses a 4-frequency multiplier to generate the Ka-band radio frequency signal required by the target simulator, and the signal contains a doppler shift signal. Then, the radio frequency signal is amplified by the amplifier 3-1, the output signal is sent to the attenuation unit, and the power is adjusted to the range required by the work by the modulator 3-5 under the control signal of the attenuator 3-4, so that the output signal is generated. Of these, the amplifier 3-1 is preferably a 4-frequency multiplier amplifier.

Because the output signal is a pulse signal modulated by the modulator 3-5, parameters such as pulse width, repetition frequency, power, delay and the like of the output signal can be set, and frequency characteristics such as center frequency, linear frequency modulation, Doppler frequency and the like of the output signal can also be set in a software interface.

Preferably, the underlying hardware control module 4 includes: a power control unit and a modulation waveform generation unit.

The power control unit and the modulation waveform generating unit are both connected with the millimeter wave module 3.

The power control unit is used for controlling the output power of the output signal. The modulation waveform generating unit is used for providing synchronous pulses and generating pulse modulation signals.

Wherein, the power control unit includes: a scaling attenuation control circuit 4-1, a power attenuation control circuit 4-2 and a modulation waveform generation circuit 4-3.

The scaling attenuation control circuit 4-1 and the power attenuation control circuit 4-2 are both connected with the millimeter wave module 3. The scaling attenuation control circuit 4-1 and the power attenuation control circuit 4-2 are in data interaction with the main control computer module 5 through a bus 9.

The main function of the modulation waveform generation circuit 4-3 is to provide a timing reference, i.e. to provide synchronization pulses, for the whole system. Meanwhile, a plurality of modulation signals with respectively controllable time delay, pulse width, motion speed, signal waveform and repetition frequency are generated.

The scaling attenuation control circuit 4-1 and the power attenuation control circuit 4-2 complete the control of the millimeter wave output signal power through the control of the attenuation unit. The power control of the output signal can simulate the power variations caused by the near-far of the target and the fluctuation characteristics of the target.

The design idea and the design process of the power control unit provided by the invention are as follows:

because the selected VCO has high oscillation frequency, wide bandwidth and large fluctuation of in-band power along with working temperature and environment, and is influenced by standing wave characteristics and insertion loss characteristics of a microwave device of the circuit, the frequency-power characteristic curve of an output signal cannot achieve an ideal flat linear state. The millimeter wave coherent radar target simulator has great difference of output power when working at different frequency points, and is obviously very unfavorable for the test of a radar seeker. Therefore, it is necessary to unify the power of the output signals to ensure that the output power corresponding to each frequency point signal is substantially the same within the working bandwidth of 3 GHz. On the other hand, since the strengths of the plurality of target signals and the plurality of interference signals are controlled by controlling the magnitude of the output signal power, it is also necessary to attenuate the output power.

Based on the design requirements, the main control circuit board in the power control unit can be composed of a power detector, 12 bits of A/D, 12 bits of D/A, a data latch, a current drive unit, an attenuation unit and the like. Wherein, AD7476A is adopted as A/D. D/A adopts AD 9752. The data latches are done within the FPGA (Spartan3E XC3S 500E). The current drive employs AD 8021. The attenuation unit and the detector are arranged in the microwave case, and the rest devices are arranged on the power control circuit board.

The power calibration is a method for realizing the output power normalization of the system, namely, a method for adding a preset value in an attenuation unit is used for unifying attenuation starting points of the output power of the whole system, so that the millimeter wave coherent radar target simulator has a unified standard when testing or measuring.

Power scaling is a closed-loop control process that first looks for criteria. The conventional power calibration is realized by adopting a power probe, and has the defects of low speed, high cost and poor controllability. Based on the defect, the simulator provided by the invention adopts the power detection level as a criterion to carry out power calibration, and the method has the advantages of clear realization idea, simple circuit, high calibration speed, good controllability and the like.

The power detection level is detected by a power detector, and corresponds to the output power of the oscillation source, and although the power detection level slightly fluctuates depending on the temperature, the error is considered to be within an allowable range. The frequency characteristic of the power detector is obvious, when the frequency characteristic is selected, a broadband device is selected, the bandwidth requirement of the radar simulator is met, and the detection level output is ensured to be in a detection output linear region (the output of the power detector can be roughly divided into a saturation region, a linear region and a noise inundation region) on the whole frequency band.

The power scaling circuit is constructed as shown in fig. 2, and power scaling is a closed-loop control process, and the control is realized by firstly searching a criterion and designing a power scaling control program. The calibration power of the target simulator is 7dBm, and the working process is as follows:

starting from 0dB attenuation, gradually increasing the attenuation of the scaling attenuator 3-2 by using an increasing power attenuation code, simultaneously detecting the microwave output power at the output end of a radio frequency signal by using a power meter, and acquiring microwave output power data in a circuit through links such as detection, A/D and the like. When the output power is shown to be 7dBm, the a/D data and the power attenuation code at that time are saved. The a/D data at this time will be used as the criterion for the actual power scaling, and the power attenuation code at this time can be used as the initial control code for the power scaling. When the simulator starts the power calibration function, the power detector continuously inputs the power attenuation code obtained by A/D conversion of the detection level value corresponding to the microwave power to the computer, the computer compares the input with the criterion, and then outputs an instruction to adjust the attenuation of the calibration attenuator 3-2 until the detection level value is consistent with the criterion.

When the output power measured by a power meter at the output port of the system is 7dBm by adjusting the attenuation of the scaling attenuator 3-2, the power detector corresponds to an output level value, a binary code of the level value is obtained by A/D conversion, and the binary code is used as a criterion and written into a computer control program.

The temperature probe measures the environment temperature and has the temperature compensation effect on the power attenuation. The detector plays a role of a power probe, one of the keys for reducing detection errors is to select a detector with large dynamic, wide bandwidth and good line shape, and meanwhile, the frequency response characteristic and the temperature characteristic of the detector are compensated in a control program.

Because the dynamic range requirement of power attenuation is 100dB, the attenuation unit is formed by connecting two attenuators in series. When the power attenuation is less than or equal to 50dB, only one attenuator is enabled. When the power attenuation requirement is more than 50dB, the attenuation is firstly fixed by 50dB by one attenuator (scaling attenuator 3-2), and the rest is attenuated by the other attenuator (attenuator 3-4).

The automatic power attenuation is achieved with a repetition period as a unit of time. The PC104 calculates the power change step length by taking the repetition period as a unit according to the requirements of the radar repetition period and the power attenuation speed, then looks up the table to find out the corresponding power attenuation control code, and specially lists the power attenuation control code into a temporary working table. After the work is started, the PC104 continuously inquires the arrival condition of the synchronous pulse, and when the synchronous pulse arrives, the attenuation control code is searched in the sequence of the temporary work table and is sent to control the attenuator 3-4. When the next synchronization pulse arrives, the next attenuation control code is checked again. The start and stop of the automatic power decay should coincide with the delay of the echo pulse (target motion simulation), and therefore the setting of the starting power is entered by the front panel keyboard. The termination power value depends on the attenuation speed and the delay range and is informed by the delay termination signal.

The core of the power control is to send appropriate attenuation codes to the attenuators 3-4 to achieve the purpose of controlling the output power. The PC104 calculates corresponding attenuation codes according to the distance of the target and the fluctuation characteristics of the sectional area of the target, then sends the attenuation codes to the main control circuit board in parallel, the main control circuit board forms analog level after D/A conversion, and the analog level is driven to become a current signal to control the attenuators 3-4 to attenuate, thereby realizing the real-time control of the target power. The power attenuation control principle is shown in fig. 3.

Thus, the power control unit is designed to include: the main control circuit board, the scaling attenuation control circuit 4-1 and the power attenuation control circuit 4-2 are used for accurately controlling the output power of the millimeter wave signals.

Preferably, the master control computer module 5 includes: an input unit 5-1 and a PC104 embedded computer 5-2.

The input unit 5-1 is connected to the PC104 embedded computer 5-2.

The input unit 5-1 is used for entering operating parameters. The working parameters comprise: an operating mode, a power attenuation value, and a pulse delay value. The PC104 embedded computer 5-2 is used for generating control data according to the working parameters.

The input unit 5-1 provided by the invention is preferably a panel keyboard.

Various parameters (including working mode, pulse delay, movement speed, power attenuation and the like) of the simulator are set through the panel keyboard, after the PC104 embedded computer 5-2 receives information transmitted from the panel keyboard, control data are sent to the bottom layer hardware control module 4 through an ISA bus through software processing, and meanwhile, various parameters of the simulator are displayed on the display screen 5-3.

In order to facilitate remote control of the simulator, the composite seeker holohedral millimeter wave target simulator provided by the invention can further comprise: a remote control interface module 6.

The remote control interface module 6 performs data interaction with the main control computer module 5.

The remote control interface module 6 is used for realizing information interaction and signal remote transmission between the radar and the composite seeker full-coherent millimeter wave target simulator and between the remote control equipment and the composite seeker full-coherent millimeter wave target simulator.

The remote control interface module 6 has an RS422 and GPIB interface, and a remote control system implanted therein can complete program control of the target simulator. The main function of the remote control interface module 6 is to realize the information exchange between the radar and the simulator and the remote control equipment and the simulator and the transformation of the signals during the remote transmission. The specific structure of the remote control interface module 6 is shown in fig. 4. The radar control signal DB15 in fig. 4 mainly includes a pulse width selection signal and a bandwidth modulation signal at the time of chirp.

In addition, in order to further improve the structure of the simulator, the composite seeker holohedral millimeter wave target simulator provided by the invention further comprises: a power supply module 7 and a self-test module 8.

The power module 7 is used for providing electric energy for the composite seeker holophase-coherent millimeter wave target simulator. The self-checking module 8 is used for checking whether the communication between the modules is normal.

Wherein, power module 7 includes: the simulator used by the invention has the capability of automatic detection, can stably output various power supply voltages required by the simulator, has a perfect protection circuit, and has the protection capability of overvoltage, overcurrent and the like.

A self-checking module 8 comprising an automatic detection and sampling circuit is arranged in each functional module, and the purpose is to facilitate the equipping personnel to maintain and repair the radar simulator in real time. For example, the power module 7 is provided with a power detection and sampling circuit, and the millimeter wave module 3 is provided with a frequency detection circuit, a radio frequency output power detection circuit, a software and hardware communication test circuit, and a phase-locked loop detection circuit.

Under the control of PC104 embedded computer 5-2 and program software, various self-checking circuits automatically sample and detect various modules and circuits according to the designed working rhythm, and convert the collected various signals into signal forms which can be recognized by the computer through preliminary processing, and then send the signals to PC104 embedded computer 5-2. After logical operation, various self-checking instructions and signals are output to each module of the simulator in the PC104 embedded computer 5-2, the functions of self-checking, work detection and self-checking of the computer according to a preset program are completed, and fault information processed by the computer is sent to the panel function selection and logic control unit and displayed on the display.

The simulator provided by the invention has high working frequency and wide frequency band, can better ensure the coherence of the output millimeter wave target characteristic signal and an external phase reference clock, and can also ensure better phase noise and stray performance.

Because the bandwidth of the signal source is wide, the in-band power fluctuation is large, and the power control of the output signal is required to simulate the power change caused by the distance of a target and the fluctuation characteristic of the target. This puts high demands on power scaling, and a high-stability attenuation unit, a fast and accurate numerical control circuit and an efficient control algorithm must be provided.

As another embodiment of the present invention, a specific structure of a front panel of the composite seeker holophase-coherent millimeter wave target simulator provided by the present invention is shown in fig. 5, and a specific structure of a rear panel is input into fig. 6.

In addition, the method for generating multiple targets and multiple interference signals in the composite seeker holohedral millimeter wave target simulator provided by the invention specifically comprises the following steps:

in the current millimeter wave radar test, two millimeter wave signal sources are needed to detect the target selection performance and the anti-interference performance of the millimeter wave seeker. For example: in order to detect the anti-distance drag interference performance of the millimeter wave seeker, two signal sources need to be adjusted to an external trigger working state, the frequency of the signal sources needs to be finely adjusted, the delay of one signal source is adjusted to be about 70 mu s, the output power is about 15dB higher than the radar capture sensitivity, the delay of the other signal source is adjusted to be about 60 mu s, the output power is adjusted to be-10 dBm, and the signal sources need to move backwards at a speed of more than or equal to 1 mu s/1 s. The test method has the advantages of high cost on one hand and complex operation on the other hand.

In order to reduce the cost and make the test more simple and convenient, the simulator provided by the invention increases the simulation of a plurality of targets and a plurality of interference signals, realizes the function of generating a plurality of targets and a plurality of interference signals in a single high-frequency channel, and greatly reduces the cost. The simulator provided by the invention simulates and realizes a plurality of radar radio frequency echoes and a plurality of interference signals by utilizing a large-scale programmable logic device FPGA, and provides a comprehensive test means for the performance of the seeker under a complex electromagnetic environment.

In order to achieve multiple targets and trailing interference, co-frequency asynchronism and continuous wave interference signals in one high-frequency channel, the power of each signal needs to be controlled in real time. The simulator provided by the invention adopts a digital power management technology, can generate complex control signals and greatly simplifies a control interface circuit. The parameters of the radar target echo mainly comprise power, pulse width and distance. The radar signal power (attenuation) and the control code of the modulator 3-5 are combined into a radar "signature". The characteristic word consists of two parts: a power code and a target indication. The power code is used to control the amount of attenuation of the attenuator 3-4 and the target indication is used to control the switching of the modulator 3-5.

When a target is output, a power control code is derived based on the target's indication code, and the power control code is applied to the scaling attenuator 3-4 when the modulator 3-5 is turned on. And when another target output is output, the power control code is obtained and then applied to the attenuator 3-4. Therefore, the power of a plurality of targets can be controlled respectively, and the requirement of multiple targets is met in power control. In this way the response time of the attenuator 3-4 is very demanding, because the duration of the simulated echo pulse is short, and if the response time of the attenuator 3-4 is too long, the actual output power will differ greatly from the set power.

The method for realizing the trailing interference, the same frequency asynchronous interference and the continuous wave interference is similar to the multi-target method, and the method for managing the digital power is also adopted to respectively control the power of each interference signal.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims

1. A composite seeker holophasic millimeter wave target simulator is characterized by comprising: the system comprises a reference signal source selection module, a frequency synthesis module, a millimeter wave module, a bottom hardware control module and a main control computer module;

2. The composite seeker all-coherent millimeter wave target simulator of claim 1, wherein the reference signal source selection module comprises: a selection switch and a reference signal power divider;

3. The composite seeker all-coherent millimeter wave target simulator of claim 1, wherein the frequency synthesis module comprises: the frequency synthesizer, the direct digital frequency synthesis chip, the frequency control circuit and the up-converter;

4. The composite seeker all-coherent millimeter-wave target simulator of claim 1, wherein the millimeter-wave module comprises: a frequency multiplier, an amplifier, an attenuation unit and a modulator;

5. The composite seeker all-coherent millimeter-wave target simulator of claim 1, wherein the underlying hardware control module comprises: a power control unit and a modulation waveform generation unit;

6. The composite seeker all-coherent millimeter wave target simulator of claim 5, wherein the power control unit comprises: a scaling attenuation control circuit and a power attenuation control circuit;

7. The composite seeker all-phase-coherent millimeter wave target simulator of claim 1, wherein the master control computer module comprises: an input unit and a PC104 embedded computer;

the input unit is connected with the PC104 embedded computer;

8. The composite seeker all-coherent millimeter wave target simulator of claim 1, further comprising: a remote control interface module;

9. The composite seeker all-coherent millimeter wave target simulator of claim 1, further comprising: the system comprises a power supply module and a self-checking module;