CN110988830A - Multi-frequency-band radar target simulator - Google Patents

Abstract

The invention discloses a multi-band radar target simulator, and aims to provide a target simulator which is stable in working performance, wide in working bandwidth, large in signal control dynamic range and capable of automatically identifying frequency band switching. The invention is realized by the following technical scheme: the device comprises a transmitting synchronizer connected with an FPGA, a power divider connected with a reference crystal oscillator, a phase-locked loop, a DAC (digital-to-analog converter) and an ADC (analog-to-digital converter), a C wave band and Ka wave band receiving and transmitting antenna connected with a sampling phase-locked frequency synthesizer through an electronic radio frequency switch, the frequency of a radio frequency signal is measured through a rapid frequency measurement module, the frequency is down-converted to an intermediate frequency and is output to the FPGA, a frequency control word of an up-conversion digital phase-locked loop PLL (phase-locked loop) is calculated and adjusted, a corresponding frequency control word is output to generate a local oscillator and two local oscillator frequency signals corresponding to up-conversion, the reduced intermediate frequency signal and the up-conversion form C wave band and Ka wave band broadband.

Description

Multi-frequency-band radar target simulator

Technical Field

The invention relates to a design of a multi-band radar target simulator and a signal source based on copy forwarding, which is mainly used for detecting the performance and the precision of a radar.

Background

In the development and debugging process of modern radars, performance test and index acceptance of a radar system are very important links, complete machine identification and external field test of the radar system are required to provide test signals through real targets in a test target range, a large amount of manpower, material resources and financial resources are consumed, and the development and development period of the radar system is prolonged.

In recent years, daily test and calibration for radar systems are receiving much attention, and ensuring the performance and function of radar systems becomes one of the research hotspots of radar technology with respect to how to conveniently perform simulation target test on radar systems. The radar target simulator can also be arranged in the detection equipment of the radar system aiming at the condition, and the channel gain, the phase stability and the signal processing function and precision of the receiving channel of the radar system can be detected and calibrated in time so as to ensure that the full life cycle performance of the radar is excellent. The target simulator device is a powerful tool for radar testing, can generate multi-target echo signals in a static mode, provides required dynamic target echo signals for a radar system, and completes related tests and experiments. In the radar development test, the debugging efficiency of radar processing can be greatly improved, the test period of a radar system is shortened, the test and development cost is saved, the verification capability of a radar comprehensive processing system can be enhanced, the adaptability of the battlefield situation of the system is improved, the system research and development time is shortened, the system research and development progress is accelerated, the efficiency is improved, and the cost is saved. The simulation target comprises: echo signal delay control and power control, point target signal simulation, meteorological target signal simulation of cloud cluster, turbulence, wind shear and the like, surface target signal simulation of RBM, DBS, SAR and the like, and interference signal simulation of false target, noise interference and the like.

Generally, the target echo signal mainly includes three kinds of information: amplitude information, which is brought about by changes in factors such as distance, target radar reflection cross-sectional area (Rcs), antenna pattern modulation, and the like; frequency domain information, i.e., target doppler frequency; and time domain information, i.e., distance delays reflecting the distance of the target. The range simulation is calculated according to the equation for a reflection radar, and the signal-to-noise ratio should be zero when the range reaches Rmax. Meanwhile, the time of the analog signal source for outputting the analog pulse signal is changed through the distance delayer, and time simulation on the distance is generated. When simulating the beacon mode state, the radar must compute according to the beacon mode. The accuracy of the target simulator is theoretically very high, but when it is mounted on the radar, its accuracy is that of the radar. Although different receivers and different servo systems are the same simulator, it exhibits different accuracies. The existing method is to directly introduce the three kinds of information on the basis of radar transmission signals to generate target echo signals. In the aspect of processing three kinds of information, corresponding technical approaches exist at present, for example, amplitude simulation can be realized by a large dynamic program control attenuator, target Doppler frequency can be realized by a Direct Digital Synthesizer (DDS), and the target Doppler frequency can also be realized by operation of a high-speed digital signal processing system. The realization of distance delay is relatively difficult in the past relative to the realization of amplitude and frequency information, and the past method adopts a surface acoustic wave delay method to realize the distance delay, but the signal quality is poor, the bandwidth is narrow,

the target simulator can be divided into four parts of a sum signal former, a difference signal former, a microwave signal source, a sum signal controller, a difference signal controller and a route generator. The generated target signal is added to the sum, azimuth and elevation difference channels of the main channel by several directional couplers. The system mainly comprises a control computer, a receiver, a transmitter, a full-band frequency synthesizer, a transmitting-receiving antenna and a DRFM unit, wherein a radio frequency signal radiated by a radar to be detected is transmitted to the receiver through the receiving antenna, the receiver completes the amplification of the radio frequency signal, the radio frequency signal is converted into an intermediate frequency signal through down-conversion and is provided for the DRFM, the DRFM completes the acquisition and the storage of the intermediate frequency signal, generates a required target and ground clutter signal according to requirements, modulates the intermediate frequency signal on a digital intermediate frequency signal, and outputs an analog intermediate frequency signal through digital-to-analog conversion to be transmitted to the transmitter; in order to ensure that the frequency of the signals transmitted by the simulator is consistent with the frequency of the received signals, a high-stability frequency synthesizer is required to provide local oscillator signals required by up-conversion and down-conversion for the transmitter and the receiver.

In order to realize the above functions of the simulator, the performance indexes of the radio frequency front end of the simulator are required to be as follows: (1) signal waveform: an arbitrary waveform signal; (2) radio frequency operating frequency: the C-band bandwidth is 600MHz, and the Ka-band bandwidth is 1 GHz; (3) medium frequency bandwidth: (30-60) MHz; (4) pulse repetition frequency range: 30-10000 Hz; pulse width: 1-300 mus; (5) receiver input signal dynamic range: 60 dB; transmitter output signal dynamic range: 80 dB; (6) functional indexes are as follows: simulating a target distance: 240 m-60 km; distance precision: 10 m; (7) simulating a target speed: -2000 to 2000 m/s; speed precision: 1.5 m/s.

The receiver consists of a C-band receiving component and a Ka-band down converter, and has the functions of receiving C-band and Ka-band broadband radio-frequency signals transmitted by a radar, dividing the signals into two paths after filtering, gain control and amplification, detecting radar radio-frequency pulses by a logarithmic detection amplifier in one path, and comparing the radar radio-frequency pulses with detection level signals to generate video detection signals serving as synchronous signals of the DRFM; the other path of the signal is converted into an intermediate frequency signal, and the intermediate frequency signal is subjected to low-pass filtering and then sent to DRFM for processing. The transmitter consists of a C-band transmitting component and a Ka-band up-converter and consists of an intermediate frequency up-conversion module, a broadband radio frequency up-conversion module and a broadband power amplification module. With the increasing development of radar technology, the task of radar includes not only measuring the distance, azimuth and elevation angle of a target, but also measuring the velocity of the target and other information about the target. However, the signal transmitted by the radar does not contain any information, and only when the signal transmitted by the radar hits the target, the target modulates and reflects the signal (the reflected signal is called an echo), and the echo at this time contains the information of the target, and the information about the target can be obtained by processing the echo. The radar target simulation is mainly used for reproducing radar echo signals containing radar target information and clutter information. In the development and debugging process of a modern radar system, the test of radar performance and indexes is an important link. If the whole machine debugging and the performance identification of the radar adopt outfield test flight, namely a real target (such as an airplane) provides a test signal for the radar, not only a great deal of manpower, financial resources and material resources are needed, but also the development period of the system is prolonged, and even under certain conditions (such as severe weather), the test flight is impossible. The radar target simulation technology is a product of combining a system simulation technology and a radar technology, a simulated object is a target and an environment of a radar, and a simulation result is that a radar echo signal containing radar target and target environment information is reproduced. In practice, these radar return signals can be considered to be formed by a recurring waveform of the transmitted waveform after being delayed and doppler-shifted.

The simulation technology is widely used for debugging and performance evaluation of radar subsystems, and is used for analyzing and debugging the system back stage and detecting the performance and indexes of the whole radar under the condition that the front end of the radar does not have. By adopting the radar target simulation technology, the development period of the radar can be shortened, and the development cost of the radar, the training cost of a radar operator and the like are reduced. The multi-target simulator is mainly used for the inspection, operation training and pre-task drilling of the multi-target tracking measurement mode of the radar. The simulators simulate a plurality of moving targets, and the key of the simulation is the real-time property and the authenticity of the targets, namely, various real-time moving postures of the targets must be simulated so as to verify the measurement and tracking of the radar on the moving characteristics (such as distance, speed and acceleration) of the targets with various moving postures. Before the radar leaves a factory, target echoes required by radar debugging and verification, characteristic signals such as complex electromagnetic environments and the like are generated, the radar interception tracking process, the characteristic extraction and identification functions are checked, the target capacity and the data rate index are verified, the target classification accuracy and processing time, the target identification rate and the interception, tracking and identification capabilities of the radar in an interference environment are checked, and external field tests are effectively reduced. Planning and testing radar performance indexes according to needs, generating specific target information and environment information, finding problems and defects in a radar system, adjusting radar system parameters, and optimizing and improving the comprehensive performance of the system. The search for a target simulator which has the advantages of small volume, light weight, simple and convenient operation, accurate test, no environmental influence and suitability for testing and calibrating various radar systems is the research direction.

Disclosure of Invention

The invention aims to provide a multi-band radar target simulator which has the advantages of small volume, light weight, low cost, stable working performance, wide working bandwidth and large signal control dynamic range, can realize noise modulation interference in a frequency band and can automatically identify frequency band switching aiming at the defects and the limitations of the prior art. The method adopts an external radar target simulator to detect the performance and the function of the phased array radar.

The technical solution for realizing the invention is as follows: a multi-band radar target simulator comprising: the transmitting synchronizer connected with the FPGA, the power divider connected with the reference crystal oscillator, the phase-locked loop PLL, the digital-to-analog (D/A) converter DAC and the analog-to-digital/A (D) converter ADC, and the C-band and Ka-band receiving and transmitting antennas of the sampling phase-locked frequency synthesizer PDRO are connected through the electronic radio frequency switch, and the transmitting synchronizer is characterized in that: dividing the reference frequency signal into three paths through a power divider, wherein one path is sent to a phase-locked loop PLL1, the first local oscillation frequency LO1 and the radio frequency signal of a C transmitting antenna perform down-conversion to obtain a uniform first intermediate frequency signal and generate a Ka waveband frequency mixing reference, and the other path passes through a phase-locked loop PLL2, the second local oscillation frequency LO2 and the radio frequency signal of the C transmitting antenna perform down-conversion to generate an L waveband intermediate frequency mixing reference; after power division, the third path of reference frequency signal is sent to the DAC and the ADC through the FPGA to be used as a core model clock and a sampling clock of the multi-band target simulator of the system; the receiving antenna of C wave band and Ka wave band receives the transmitting signal of the tracking radar, the receiving channel measures the frequency of the radio frequency signal through the rapid frequency measuring module, down-converts the radio frequency signal to intermediate frequency, outputs to the corresponding frequency control code to FPGA, FPGA converts the transmitting intermediate frequency analog input signal into the sampling of the digital signal through ADC, calculates to adjust the frequency control word of the up-conversion digital phase-locked loop PLL, outputs the corresponding frequency control word to generate the corresponding up-conversion corresponding local oscillator and two local oscillator frequency signals, simultaneously FPGA samples and stores the intermediate frequency signal, outputs the baseband data to DAC through time delay to realize the reduction of the intermediate frequency signal, the reduced intermediate frequency signal is mixed, frequency-selected and amplified with the up-conversion local oscillator and two local oscillator frequency signals, after up-conversion band-pass filtering and amplitude control, C wave band and Ka wave band broadband radio frequency signals are formed, the C wave band and Ka wave band antenna in the required working frequency band are controlled and gated through the electronic radio frequency switch, and outputting various waveform signals in the required frequency band, and radiating the signals to the space through a transmitting antenna.

Compared with the prior art, the invention has the following beneficial effects:

1) small size, light weight and low cost.

The invention adopts a transmitting synchronizer, a power divider, a phase-locked loop PLL, a digital/analog (D/A) converter DAC and an analog/digital/A (D) converter ADC which are connected with a field programmable gate array FPGA, and a multi-band radar target simulator which is formed by connecting a C-band transceiver antenna and a Ka-band transceiver antenna of a sampling phase-locked frequency synthesizer PDRO through an electronic radio frequency switch. This radar target simulator utilizes radar transmission technique and system simulation design to combine together, can produce alone and contain the arbitrary waveform transmitting signal of target distance, position and altitude information, also can realize the deceptive interference to radar system, can also be through receiving radar system's transmitting waveform signal, through quick frequency measurement, the intermediate frequency sampling behind the lower mixing, data storage forwards, time delay back, restore into the transmitting signal that radar transmitting waveform phase is coherent on the radio frequency, realize the detection to radar system's receiving channel. The target simulator can be directly operated through the operation interface, in the test process, the multi-band radar target simulator and the synchronous generator are controlled through optical fiber communication, and the frequency band switching is automatically identified through the operation interface. The method can realize the measurement of array surface transmitting power, radar ranging precision, radar angle measurement precision and improvement factors of the whole radar in the frequency band.

2) The working performance is stable, the working bandwidth is wide, and the signal control dynamic range is large.

Dividing a reference frequency signal into three paths through a power divider, wherein one path is sent to a phase-locked loop PLL1, a first local oscillation frequency LO1 and a radio frequency signal of a C transmitting antenna perform down-conversion to obtain a uniform first intermediate frequency signal and generate a Ka waveband frequency mixing reference, and the other path passes through a phase-locked loop PLL2, a second local oscillation frequency LO2 and a radio frequency signal of a C transmitting antenna perform down-conversion to generate an L waveband intermediate frequency mixing reference; the third path of reference frequency signal is transmitted to the DAC and the ADC through the FPGA after power division to be used as a system clock and a sampling clock; the method has the advantages that corresponding radar transmitting waveforms are generated according to the requirements of a tested radar, the method has high-precision multi-target generation capability, frequency band switching can be automatically identified according to working frequency bands of a C wave band and a Ka wave band and specific working frequency, a first local oscillation frequency LO1 is controlled to be selected by a frequency synthesizer, the frequency synthesizer and a radio frequency signal are subjected to down-conversion to obtain a uniform first intermediate frequency signal, the two working frequency bands of the C wave band and the Ka wave band can be covered, and the universality of radar testing is improved; the multi-target simulation precision is high, and the integrity and the authenticity of the simulation target are restored to the maximum extent; the consistency of the intermediate frequency modules in the two frequency bands is ensured, the research and development difficulty is reduced, and the research and development cost is saved. The radio frequency signals radiated by the test radar are received, stored and forwarded to generate radio frequency excitation signals which are coherent with the radio frequency signals of the test radar, and noise modulation interference in a frequency band can be realized.

The invention adopts the modes of sampling, delaying and restoring the target signal to generate distance delay, can realize the adjustment of any delay time in a PRF, and has high delay precision and good signal quality. The output phase noise of the C wave band is better than-106 dBc/Hz @1 kHz; output power range: -82dBm to 2 dBm; clutter suppression is better than 65 dBc; the harmonic suppression is better than 55 dBc. The Ka-band output phase noise is better than-90 dBc/Hz @1 kHz; output power range: -75dBm to 10 dBm; clutter rejection was better than 55 dBc. The working performance is stable, the working bandwidth is wide, the signal control dynamic range is large, and the harmonic suppression and anti-interference capability is strong.

The method can support the system to complete the precise simulation of the radial speed, the distance and the RCS of the targets in multiple batches with continuous waves and pulse systems, and can be used for examining the resolution and the multi-target processing capability of the tested radar target under the condition of an external field.

Drawings

FIG. 1 is a functional block diagram of a multi-band target simulator of the present invention;

FIG. 2 is a multi-band target simulator core model of the present invention;

FIG. 3 is a block diagram of a multiband target simulator baseband process.

Detailed Description

See fig. 1. In a preferred embodiment described below, the multiband radar target simulator comprises: the device comprises a transmitting synchronizer connected with a field programmable gate array FPGA, a power divider connected with a reference crystal oscillator, a phase-locked loop PLL, a digital-to-analog (D/A) converter DAC and an analog-to-digital/A (D) converter ADC, a C-band and Ka-band receiving and transmitting antenna, a mixer, an amplifier, a filter, an L-phase-locked loop, a C-phase-locked loop, a Ka-phase-locked loop, a C-band and Ka-band receiving and transmitting antenna, wherein the C-band and Ka-band receiving and transmitting antenna is connected with a sampling phase-. Dividing the reference frequency signal into three paths through a power divider, wherein one path is sent to a phase-locked loop PLL1, the first local oscillation frequency LO1 and the radio frequency signal of a C transmitting antenna perform down-conversion to obtain a uniform first intermediate frequency signal and generate a Ka waveband frequency mixing reference, and the other path passes through a phase-locked loop PLL2, the second local oscillation frequency LO2 and the radio frequency signal of the C transmitting antenna perform down-conversion to generate an L waveband intermediate frequency mixing reference; after power division, the third path of reference frequency signal is sent to the DAC and the ADC through the FPGA to be used as a core model clock and a sampling clock of the multi-band target simulator of the system; the receiving antenna of C wave band and Ka wave band receives the transmitting signal of the tracking radar, the receiving channel measures the frequency of the radio frequency signal through the rapid frequency measuring module, down-converts the radio frequency signal to intermediate frequency, outputs to the corresponding frequency control code to FPGA, FPGA converts the transmitting intermediate frequency analog input signal into the sampling of the digital signal through ADC, calculates to adjust the frequency control word of the up-conversion digital phase-locked loop PLL, outputs the corresponding frequency control word to generate the corresponding up-conversion corresponding local oscillator and two local oscillator frequency signals, simultaneously FPGA samples and stores the intermediate frequency signal, outputs the baseband data to DAC through time delay to realize the reduction of the intermediate frequency signal, the reduced intermediate frequency signal is mixed, frequency-selected and amplified with the up-conversion local oscillator and two local oscillator frequency signals, after up-conversion band-pass filtering and amplitude control, C wave band and Ka wave band broadband radio frequency signals are formed, the C wave band and Ka wave band antenna in the required working frequency band are controlled and gated through the electronic radio frequency switch, and outputting various waveform signals in the required frequency band, and radiating the signals to the space through a transmitting antenna.

Dividing a reference crystal oscillator signal into four paths through a power divider, and sending one path of the reference crystal oscillator signal to a Ka phase-locked loop to generate a frequency mixing reference for up-down frequency conversion of a Ka frequency band; the second path of reference crystal oscillator signal is sent to an L phase-locked loop and used for generating a frequency mixing reference of an L-band signal; the third path of reference crystal oscillator signal is sent to a C phase-locked loop and used for generating a mixing reference of the C-band signal; and the fourth path of reference crystal oscillator signals are respectively sent to clock input ends of the FPGA, the DAC and the ADC to be used as sampling clocks.

When the working Ka wave band is received, the electronic radio frequency switch is connected with a Ka down-conversion channel, a Ka receiving antenna receives signals, the signals are down-converted through frequency mixing reference with the Ka frequency band to output C wave band signals, the C wave band signals are down-converted through frequency mixing reference with the C wave band to output L wave band signals, and then the signals are mixed with the L wave band signals to output intermediate frequency signals to be sent to an ADC for sampling. When a working C wave band is received, the electronic radio frequency switch is switched on the C wave band receiving antenna, a receiving signal is down-converted by the frequency mixing reference with the wave band to output an L wave band signal, and then the L wave band signal is frequency mixing reference with the L wave band signal to output an intermediate frequency signal which is sent to an ADC for sampling. The FPGA controls the ADC to digitally sample an input intermediate frequency signal, the sampled digital information is stored in the high-speed memory, after the time delay relative to the PRF inside the FPGA is carried out, the digital information in the high-speed memory is extracted and sent to the DAC according to an internal time sequence, the digital information is reduced into a delayed intermediate frequency signal, the intermediate frequency signal is mixed with an L-waveband mixing reference, then mixed with a C-waveband mixing reference, amplified and filtered, and then sent to the input end of the electronic radio frequency switch, the electronic radio frequency switch outputs one end which is directly connected to a C-waveband transmitting antenna under the control of a frequency band selection signal of the FPGA, outputs a C-waveband analog target signal, and outputs a Ka-waveband transmitting signal after the other end of the electronic radio frequency switch outputs the other end of the electronic radio frequency switch is mixed.

The Ka wave band receiving antenna receives a transmitting signal of a Ka wave band of a radar to be detected, the receiving channel sends out an intermediate frequency signal after three times of frequency mixing, the FPGA samples the transmitting intermediate frequency signal through the ADC and stores the signal into a storage space inside the FPGA, after the signal generator receives external PRF triggering, after fixed time delay is carried out through internal time sequence, the FPGA extracts, stores, transmits intermediate frequency data and sends the data to the DAC, and a transmitting baseband signal is generated.

The transmitting baseband is mixed with the L-band frequency mixing reference, then mixed with the C-band transmitting intermediate frequency, and then mixed with the Ka-band frequency mixing reference to generate a transmitting excitation signal, and the transmitting excitation signal is modulated and amplified by a modulation amplifier and then sent out. The network control, PRF signal and 10MHz clock of the signal generator are sent to FPGA, FPGA is modulated and then sent to the optical fiber transceiver module, and then sent to FPGA in the baseband processing unit through the optical fiber for demodulation, and then the working state of the signal generator is controlled.

The method comprises the steps that a C-band receiving antenna receives a transmitting signal of a C-band of a radar to be detected, a receiving channel sends out an intermediate frequency signal after two times of frequency mixing, an FPGA samples the transmitting intermediate frequency signal through an ADC and stores the signal into a storage space inside the FPGA, a signal generator receives external PRF trigger and then carries out fixed time delay through internal time sequence, the FPGA extracts, stores and transmits transmitting intermediate frequency data to the DAC to generate a transmitting baseband signal, the transmitting baseband is mixed with an L-band frequency mixing reference and then mixed with a C-band transmitting intermediate frequency to generate a transmitting excitation signal, and the transmitting excitation signal is modulated and amplified through a modulation amplifier and then sent out.

See fig. 2. The DAC, the FPGA and the ADC are connected with a receiver, the FPGA is connected with a working time sequence module, a communication control module and a high-speed memory to form a multi-band target simulator core model, the working time sequence module sends the received measured radar time sequence and the measured radar time sequence interacted with the terminal into the FPGA through the communication control module, and the received measured radar time sequence and the measured radar time sequence are stored in the high-speed memory. The receiver down-mixes the received radar transmitting signal to an intermediate frequency signal, the ADC performs analog-to-digital conversion on the intermediate frequency signal under the time sequence control of the FPGA core algorithm, and the FPGA sends the converted digital signal to the on-board high-speed memory. The working time sequence module receives the received measured radar time sequence and the measured radar time sequence interacted with the terminal, the measured radar time sequence and the working time sequence module are calculated through an FPGA core algorithm and then sent to the DAC to be converted into digital analog intermediate frequency signals, the intermediate frequency signals transmitted by the measured radar are restored and output through external time delay control, and meanwhile, corresponding transmitted intermediate frequency signals can be generated through setting scanning waveforms, bandwidths and center frequencies.

See fig. 3. Establishing a multi-band target simulator baseband processing circuit on the basis of a multi-band target simulator core model, wherein the baseband processing circuit comprises: the FPGA inputs the intermediate frequency into the FPGA as an intermediate frequency sampling clock, the FPGA sends the output clock signal CLK and the pulse repetition frequency PRF signal into the DAC module according to the output clock signal CLK and the pulse repetition frequency PRF signal of the radar to be detected, the DAC module uses the sampling clock frequency and the ADC working frequency to improve the effective digit of the output intermediate frequency signal through the frequency of the Berkeley Packet filter, and even samples some radar signals with lower frequency directly, and the signals are output through the intermediate frequency of a variable resistor, so that the application flexibility of the multi-band target simulator is improved.

The multi-band target simulator mainly has the following working modes:

a) the method comprises the following steps of a) simulating a measured radar signal, b) simulating a measured radar target, c) receiving and forwarding a measured radar and an interference mode of the measured radar, a) simulating the measured radar signal, wherein the measured radar does not start a transmitter during testing, a measured radar terminal computer sends a waveform test command, and a multi-band radar target simulator receives information of a scanning waveform, a bandwidth and a center frequency through a control interface and outputs a radar transmitting signal of a corresponding waveform and a frequency point.

The tested radar outputs an imaging CPI (cell Parameter ID) signal and a pulse repetition frequency PRF signal of an output optical engine to a transmitting synchronizer in a multi-band radar target simulator through a cable, the transmitting synchronizer modulates the CPI signal, the PRF signal and network control information to optical fibers, transmits the signals to a host of the multi-band radar target simulator through the optical fibers, demodulates the CPI signal, the PRF signal and the control information, and outputs a control signal and a waveform of a corresponding frequency point.

The tested radar can realize the test of a radar receiving channel by receiving a radar transmitting signal generated by the multi-band radar target simulator, and can measure an improvement factor of the radar.

b) Measured radar target simulation

During testing, the tested radar terminal computer sends out a waveform test command, and the multi-band radar target simulator outputs corresponding waveforms and radar emission signals of the frequency points by receiving the frequency points, the waveforms and target batches.

The tested radar outputs a CPI signal and a PRF signal which are connected to a transmitting synchronizer in the multi-band radar target simulator through a cable, the transmitting synchronizer modulates the CPI signal, the PRF signal and network control information to optical fibers, transmits the optical fibers to a host of the multi-band radar target simulator, demodulates the CPI signal, the PRF signal and the control information, and can output multi-batch multi-target simulation target signals through setting for detecting the signal processing and data processing multi-target capability of the tested radar.

c) Receiving and forwarding mode of radar to be tested

When the tested radar is tested, the transmitter of the tested radar is started, the terminal computer of the tested radar sends out the storage and forwarding control function of the multi-band radar target simulator, and the multi-band radar target simulator enters a storage and forwarding mode.

The receiver of the multi-band radar target simulator receives the transmitted signal of the radar to be tested, the frequency of the transmitted signal of the radar to be tested is quickly tested, the internal fast ADC samples, stores and delays the radar intermediate-frequency transmitted signal, the DAC synthesizes the radar transmitted signal with the same transmitted frequency, and the radar transmitted signal is radiated through the antenna after time delay, so that the sensitivity test and the trap interference of the radar to be tested can be realized.

d) Interference pattern of radar to be detected

When tested radar is tested, the tested radar terminal computer sends out the function of suppressing interference of the multi-band radar target simulator output radar, and the multi-band radar target simulator enters a radar suppressing interference mode

A DAC in the radar target simulator synthesizes digital noise signals (the frequency range is selectable and the bandwidth is selectable) in various modes, and the digital noise signals are amplified by the power amplifier and then radiated out, so that the suppression type interference on the radar receiver to be detected can be realized.

While the foregoing is directed to the preferred embodiment of the present invention, it is noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.

Claims (10)

1. A multi-band radar target simulator, comprising: the transmitting synchronizer connected with the FPGA, the power divider connected with the reference crystal oscillator, the phase-locked loop PLL, the digital-to-analog (D/A) converter DAC and the analog-to-digital/A (D) converter ADC, and the C-band and Ka-band receiving and transmitting antennas of the sampling phase-locked frequency synthesizer PDRO are connected through the electronic radio frequency switch, and the transmitting synchronizer is characterized in that: dividing the reference frequency signal into three paths through a power divider, wherein one path is sent to a phase-locked loop PLL1, the first local oscillation frequency LO1 and the radio frequency signal of a C transmitting antenna perform down-conversion to obtain a uniform first intermediate frequency signal and generate a Ka waveband frequency mixing reference, and the other path passes through a phase-locked loop PLL2, the second local oscillation frequency LO2 and the radio frequency signal of the C transmitting antenna perform down-conversion to generate an L waveband intermediate frequency mixing reference; after power division, the third path of reference frequency signal is sent to the DAC and the ADC through the FPGA to be used as a core model clock and a sampling clock of the multi-band target simulator of the system; the receiving antenna of C wave band and Ka wave band receives the transmitting signal of the tracking radar, the receiving channel measures the frequency of the radio frequency signal through the rapid frequency measuring module, down-converts the radio frequency signal to intermediate frequency, outputs to the corresponding frequency control code to FPGA, FPGA converts the transmitting intermediate frequency analog input signal into the sampling of the digital signal through ADC, calculates to adjust the frequency control word of the up-conversion digital phase-locked loop PLL, outputs the corresponding frequency control word to generate the corresponding up-conversion corresponding local oscillator and two local oscillator frequency signals, simultaneously FPGA samples and stores the intermediate frequency signal, outputs the baseband data to DAC through time delay to realize the reduction of the intermediate frequency signal, the reduced intermediate frequency signal is mixed, frequency-selected and amplified with the up-conversion local oscillator and two local oscillator frequency signals, after up-conversion band-pass filtering and amplitude control, C wave band and Ka wave band broadband radio frequency signals are formed, the C wave band and Ka wave band antenna in the required working frequency band are controlled and gated through the electronic radio frequency switch, and outputting various waveform signals in the required frequency band, and radiating the signals to the space through a transmitting antenna.

2. The multi-band radar target simulator of claim 1, wherein: dividing a reference crystal oscillator signal into four paths through a power divider, and sending one path of the reference crystal oscillator signal to a Ka phase-locked loop to generate a frequency mixing reference for up-down frequency conversion of a Ka frequency band; the second path of reference crystal oscillator signal is sent to an L phase-locked loop to generate a frequency mixing reference of an L wave band signal; the third path of reference crystal oscillator signal is sent to a C phase-locked loop to generate a mixing reference of a C-band signal; and the fourth path of reference crystal oscillator signals are respectively sent to clock input ends of the FPGA, the DAC and the ADC to be used as sampling clocks.

3. The multi-band radar target simulator of claim 1, wherein: when the working Ka wave band is received, the electronic radio frequency switch is connected with a Ka down-conversion channel, a Ka receiving antenna receives signals, the signals are down-converted through frequency mixing reference with the Ka frequency band to output C wave band signals, the C wave band signals are down-converted through frequency mixing reference with the C wave band to output L wave band signals, and then the signals are mixed with the L wave band signals to output intermediate frequency signals to be sent to an ADC for sampling.

4. The multi-band radar target simulator of claim 1, wherein: the Ka wave band receiving antenna receives a transmitting signal of a Ka wave band of a radar to be detected, the receiving channel sends out an intermediate frequency signal after three times of frequency mixing, the FPGA samples the transmitting intermediate frequency signal through the ADC and stores the signal into a storage space inside the FPGA, after the signal generator receives external PRF triggering, after fixed time delay is carried out through internal time sequence, the FPGA extracts, stores, transmits intermediate frequency data and sends the data to the DAC, and a transmitting baseband signal is generated.

5. The multi-band radar target simulator of claim 1, wherein the transmit baseband is mixed with an L-band mixing reference, mixed with a C-band transmit intermediate frequency, mixed with a Ka-band mixing reference, and modulated and amplified by a modulation amplifier to generate a transmit excitation signal; the network control, PRF signal and 10MHz clock of the signal generator are sent to FPGA, FPGA is sent to the fiber transceiver module after modulating, and then sent to FPGA in the baseband processing unit through the fiber to demodulate, the working condition of the control signal generator; the multiband radar target simulator of claim 1, wherein: when receiving working C wave band, the electronic RF switch switches on the C wave band receiving antenna, the receiving signal outputs L wave band signal by down-conversion with wave band mixing reference, then outputs intermediate frequency signal with L wave band signal mixing reference, then outputs intermediate frequency signal to ADC for sampling, FPGA controls ADC to digitally sample input intermediate frequency signal, stores the sampled digital information in high speed memory, after time delay relative to PRF in FPGA, extracts digital information in high speed memory, sends it to DAC according to internal time sequence, reduces it into delayed intermediate frequency signal, after mixing this intermediate frequency signal with L wave band mixing reference, then mixes with C wave band mixing reference, amplifies, filters, and sends it to the input end of electronic RF switch, the electronic RF switch outputs one end directly connected to C wave band transmitting antenna under the control of FPGA frequency band selection signal, outputs C wave band analog target signal, the other end of the output of the electronic radio frequency switch is mixed with Ka frequency band mixing reference frequency, amplified and filtered to output a Ka wave band transmitting signal.

6. The multi-band radar target simulator of claim 1, wherein: the method comprises the steps that a C-band receiving antenna receives a transmitting signal of a C-band of a radar to be detected, a receiving channel sends out an intermediate frequency signal after two times of frequency mixing, an FPGA samples the transmitting intermediate frequency signal through an ADC and stores the signal into a storage space inside the FPGA, a signal generator receives external PRF trigger and then carries out fixed time delay through internal time sequence, the FPGA extracts, stores and transmits transmitting intermediate frequency data to the DAC to generate a transmitting baseband signal, the transmitting baseband is mixed with an L-band frequency mixing reference and then mixed with a C-band transmitting intermediate frequency to generate a transmitting excitation signal, and the transmitting excitation signal is modulated and amplified through a modulation amplifier and then sent out.

7. The multi-band radar target simulator of claim 1, wherein: establishing a multi-band target simulator baseband processing circuit on the basis of a multi-band target simulator core model, wherein the baseband processing circuit comprises: the FPGA inputs the intermediate frequency into the FPGA as an intermediate frequency sampling clock, the FPGA sends the output clock signal CLK and the pulse repetition frequency PRF signal into the DAC module according to the output clock signal CLK and the pulse repetition frequency PRF signal of the radar to be detected, the DAC module uses the sampling clock frequency and the ADC working frequency to improve the effective digit of the output intermediate frequency signal through the frequency of the Berkeley Packet filter, and even samples some radar signals with lower frequency directly, and the signals are output through the intermediate frequency of a variable resistor, so that the application flexibility of the multi-band target simulator is improved.

8. The multi-band radar target simulator of claim 1, wherein: the multi-band target simulator mainly has the following working modes: a) the method comprises the following steps of a) simulating a measured radar signal, b) simulating a measured radar target, c) receiving and forwarding a measured radar and an interference mode of the measured radar, a) simulating the measured radar signal, wherein the measured radar does not start a transmitter during testing, a measured radar terminal computer sends a waveform test command, and a multi-band radar target simulator receives information of a scanning waveform, a bandwidth and a center frequency through a control interface and outputs a radar transmitting signal of a corresponding waveform and a frequency point.

9. The multi-band radar target simulator of claim 1, wherein: the tested radar outputs an imaging CPI (cell Parameter ID) signal and a pulse repetition frequency PRF signal of an output optical engine to a transmitting synchronizer in a multi-band radar target simulator through a cable, the transmitting synchronizer modulates the CPI signal, the PRF signal and network control information to optical fibers, transmits the signals to a host of the multi-band radar target simulator through the optical fibers, demodulates the CPI signal, the PRF signal and the control information, and outputs a control signal and a waveform of a corresponding frequency point.

10. The multi-band radar target simulator of claim 1, wherein: when the tested radar target is subjected to simulation test, the tested radar terminal computer sends out a waveform test command, and the multi-band radar target simulator outputs radar transmitting signals of corresponding waveforms and frequency points by receiving frequency points, waveforms and target batches; the tested radar outputs a CPI signal and a PRF signal which are connected to a transmitting synchronizer in the multi-band radar target simulator through a cable, the transmitting synchronizer modulates the CPI signal, the PRF signal and network control information to optical fibers, transmits the optical fibers to a host of the multi-band radar target simulator, demodulates the CPI signal, the PRF signal and the control information, and can output multi-batch multi-target simulation target signals through setting for detecting the signal processing and data processing multi-target capability of the tested radar.

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