CN113608183B - Hypersonic broadband radio frequency target simulation system - Google Patents

Abstract

The present invention discloses a hypersonic wide-band radio frequency target simulation system, comprising: a radar signal receiving frequency conversion module, a target delay digital frequency storage module, a Doppler signal generation module, an instantaneous frequency measurement module, a signal amplitude and broadband power amplifier module, a broadband local oscillator module, and a control module. By adopting the technical solution of the present invention, the distance change, Doppler frequency shift and amplitude change characteristics of the radio frequency simulation target can be accurately controlled to generate a hypersonic radio frequency simulation target, so as to achieve consistency with a real hypersonic moving target.

Description

A hypersonic broadband radio frequency target simulation system

Technical Field

The present invention belongs to the technical field of radar target simulation, and in particular relates to a hypersonic wide-band radio frequency target simulation system, in particular a shipborne radar hypersonic wide-band radio frequency target simulation generating device, which can solve the problem of lack of hypersonic target coordination in shipborne radar training.

Background technique

At present, with the development of hypersonic weapons, military powers such as the United States and Russia have successively announced plans to develop hypersonic missiles and hypersonic drones, and the target flight speed can reach more than Mach 6. The high-speed movement of the target will cause the radial distance change rate of the target to change to a higher power, making it difficult for the radar to register and track the target, and the defense is extremely difficult. At present, many radar target simulation devices have been developed. The function of these devices is mainly to simulate and generate conventional target signals, mainly for the simulation of conventional ordinary moving speed targets, and there is no method and equipment specifically for generating hypersonic target signals.

Summary of the invention

The technical problem to be solved by the present invention is to provide a hypersonic wide-band radio frequency target simulation system, which can provide a radar with a radio frequency simulation target with a maximum speed of Mach 13, and is used for radar detection performance testing and effectiveness evaluation of hypersonic targets.

To achieve the above object, the present invention adopts the following technical solution:

A hypersonic wide-band radio frequency target simulation system includes: a radar signal receiving frequency conversion module, a target delay digital frequency storage module, a Doppler signal generation module, an instantaneous frequency measurement module, a signal amplitude and broadband power amplifier module, a broadband local oscillator module, and a control module; wherein,

The radar signal is filtered and linearly amplified with low noise through the radar signal receiving frequency conversion module, and then mixed with the local oscillator signal generated by the broadband local oscillator module to obtain an intermediate frequency signal, which is output to the target delay digital frequency storage module. The time delay value of the target is read in the control module to realize the distance change simulation of the hypersonic moving target; then the Doppler frequency shift modulation information is added through the Doppler signal generation module, and the Doppler frequency shift value is also read from the control module to realize the speed simulation of the hypersonic radio frequency target; finally, the control module calculates the attenuation value of the target at the current distance in real time, and realizes the accurate simulation of the target signal amplitude through the signal amplitude and broadband power amplifier module; the instantaneous frequency measurement module measures the frequency of the radar signal in real time and accurately, and provides the target delay digital frequency storage module and the Doppler signal generation module with the accurate frequency of the test radar radiation signal through the control module, so as to realize the coherence of the simulated hypersonic radio frequency target signal and the test radar signal.

Preferably, the radar signal receiving frequency conversion module is used to receive the radar radiation signal, and perform amplitude adjustment and low-noise amplification on the received radar radiation signal, and mix it with the local oscillator signal of the broadband local oscillator module to the frequency band required for digital frequency storage, and output it to the target delayed digital frequency storage module.

Preferably, a target delay digital frequency storage module is used to delay the distance of the target, so as to simulate the appearance distance of the moving target under different antenna scanning cycles of the radar; according to the simulated target position, the control module calculates the delay value of the simulated target echo signal relative to the pulse transmitted by the tested radar; in synchronization with the detection pulse of the transmitted signal of the tested radar, the control module reads the corresponding intermediate frequency pulse signal stored in the digital RF memory according to the delay value, so as to simulate the echoes of each target corresponding to different distances.

Preferably, a Doppler signal generating module is used to perform Doppler modulation on the target echo information; the control module calculates the required Doppler signal frequency according to the target speed and the carrier frequency of the radar signal under test, and controls the direct digital frequency synthesizer to generate two orthogonal Doppler signals; the intermediate frequency digital signal modulated by the distance output by the target delay digital frequency storage module is formed into an orthogonal signal through an I/Q orthogonal extractor; the I/Q two-way intermediate frequency digital signal is orthogonally mixed with the two orthogonal Doppler signals generated by the direct digital frequency synthesizer, and the final output is the echo intermediate frequency signal after Doppler frequency modulation.

Preferably, the instantaneous frequency measurement module is used to accurately measure the signal frequency output by the radar signal receiving and frequency conversion module; the control module calculates the frequency of the current radar radiation signal under test based on the frequency of the broadband local oscillator module and the output of the instantaneous frequency measurement module to calculate the Doppler frequency of the simulated target.

Preferably, the signal amplitude and broadband power amplifier module is used to realize the modulation of the target signal amplitude, restore the simulated target intermediate frequency signal output after distance delay and Doppler modulation to the original signal frequency of the tested radar, and then amplify the simulated target signal to the required power level and transmit it to generate a hypersonic RF target signal, which is received by the radar; the control module calculates the attenuation value of the target at the current distance in real time according to the initial distance and initial attenuation of the simulated target, and controls the programmable attenuator to realize accurate simulation of the target signal amplitude.

Preferably, the broadband local oscillator module is used to generate the mixed local oscillator signal required by the receiving down-conversion circuit and the transmitting up-conversion circuit according to the operating frequency of the radar signal under test.

Preferably, the control module generates the current time delay value of the simulated target in real time according to the test radar and simulated target parameters, and transmits it to the target delay digital frequency storage module to realize the distance modulation of the simulated target; calculates the frequency of the test radar signal according to the frequency of the broadband local oscillator module and the output of the instantaneous frequency measurement module, and generates the Doppler frequency shift of the simulated target in real time and transmits it to the Doppler signal generation module to realize the Doppler modulation of the simulated target signal; generates the control parameters of the signal amplitude modulation and transmits them to the signal amplitude and broadband power amplifier module to realize the accurate simulation of the target signal amplitude; and controls the corresponding modules in real time.

Preferably, the signal amplitude and broadband power amplifier module modulates the target signal amplitude by a high-speed RF programmable attenuator.

Preferably, the Doppler modulation is controlled by a signal processing circuit, and the Doppler frequency modulation signal output by the signal processing circuit is up-converted to a center frequency of 1.5 GHz as the signal amplitude and the local oscillator signal of the broadband power amplifier module.

The hypersonic radio frequency simulation target signal generated by the present invention has obvious characteristics and is easy to be received and measured by radar; a wide-band system design is adopted to achieve a frequency coverage range of 2-18 GHz; a target with a maximum relative radial velocity of Mach 13 can be simulated and generated, and can be used for radar detection performance inspection and effectiveness evaluation of hypersonic targets.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

FIG1 is a schematic structural diagram of a hypersonic target radio frequency simulation system of the present invention;

Fig. 2 is a schematic diagram of simulating target delay;

FIG3 is a schematic diagram of the implementation of digital Doppler modulation technology;

FIG4 is a schematic diagram of Doppler frequency shift synthesis.

Detailed ways

The following embodiments will be described in detail with reference to the accompanying drawings. In the drawings or descriptions, similar or identical parts use the same reference numerals, and in actual applications, the shape, thickness or height of each component may be enlarged or reduced. The embodiments listed in the present invention are only used to illustrate the present invention and are not used to limit the scope of the present invention. Any obvious modifications or changes made to the present invention do not depart from the spirit and scope of the present invention.

As shown in Figure 1, the present invention provides a hypersonic wide-band radio frequency target simulation system, including: a radar signal receiving frequency conversion module, a target delay digital frequency storage module, a Doppler signal generation module, an instantaneous frequency measurement module, a signal amplitude and broadband power amplifier module, a broadband local oscillator module, and a control module. The present invention can accurately control the distance change, Doppler frequency shift and amplitude change characteristics of the radio frequency simulation target to generate a hypersonic radio frequency simulation target, which is consistent with the real hypersonic moving target. The functions implemented by each module are as follows:

The radar signal receiving frequency conversion module is used to receive the radar's radiation signal, adjust the amplitude of the received radar radiation signal, amplify the low noise, mix it with the local oscillator signal of the broadband local oscillator module to the frequency band required for digital frequency storage, and output it to the target delay digital frequency storage module.

The target delay digital frequency storage module is used to delay the distance of the target. The purpose of the delay is to simulate the appearance distance of the moving target under different antenna scanning cycles of the radar. The control module calculates the next appearance distance of the simulated target according to the target's movement speed and time difference, and converts it into a delay time. In the system of the present invention, the appearance distance of the simulated RF target echo on the radar screen must be strictly controlled before it can be recorded and tracked by the radar. To this end, the distance of the simulated target must be delayed with high precision. In order to realize the delay (distance) simulation of the simulated echo signal of the broadband frequency agile radar, a broadband digital frequency storage circuit is used. According to the simulated target position, the control module calculates the delay value of the simulated target echo signal relative to the pulse transmitted by the tested radar; under the synchronization of the detection pulse of the test radar transmitting signal, the control module reads the corresponding intermediate frequency pulse signal stored in the digital RF memory according to the delay value, and accurately simulates each target echo corresponding to different distances (delay values), as shown in Figure 2.

The Doppler signal generation module is used to perform Doppler modulation on the target echo information. The Doppler signal generation module uses a digital algorithm to realize the frequency modulation of the radar signal, replacing the traditional use of microwave devices such as mixers and filters to realize the frequency modulation of analog signals. The specific implementation method is shown in Figure 3: the control module calculates the required Doppler signal frequency according to the target speed and the carrier frequency of the radar signal under test, and controls the direct digital frequency synthesizer to generate two orthogonal Doppler signals; the intermediate frequency digital signal modulated by the distance output of the target delay digital frequency storage module is formed into an orthogonal signal through the I/Q orthogonal extractor; the I/Q two-way intermediate frequency digital signal is orthogonally mixed with the two orthogonal Doppler signals generated by the direct digital frequency synthesizer, and the final output is the echo intermediate frequency signal after Doppler frequency modulation.

The simulation accuracy of the Doppler frequency depends on the selection accuracy of the radar signal frequency. In order to simulate the hypersonic target of the frequency agile radar, an instantaneous frequency measurement module is added in the present invention to accurately measure the signal frequency output by the radar signal receiving and frequency conversion module. The control module calculates the frequency of the current radar radiation signal under test based on the frequency of the broadband local oscillator module and the output of the instantaneous frequency measurement module, and the Doppler frequency of the simulated target can be accurately calculated accordingly.

The instantaneous frequency measurement module is used to accurately measure the output signal (intermediate frequency signal) of the radar signal receiving frequency conversion module. It can accurately measure the frequency and phase information of the signal and transmit it to the control module.

The signal amplitude and broadband power amplifier module uses a broadband, high-speed RF programmable attenuator with a large dynamic range to modulate the target signal amplitude, restore the simulated target intermediate frequency signal output after distance delay and Doppler modulation to the original signal frequency of the tested radar, and then amplify the simulated target signal to the required power level and transmit it to generate a hypersonic RF target signal, which is received by the radar. The control module calculates the attenuation value of the target at the current distance in real time based on the initial distance and initial attenuation of the simulated target, and controls the programmable attenuator to achieve accurate simulation of the target signal amplitude.

The broadband local oscillator module is used to generate the mixing local oscillator signal required by the receiving down-conversion circuit and the transmitting up-conversion circuit according to the operating frequency of the radar signal under test.

The control module generates the current delay value of the simulated target in real time according to the test radar and simulated target parameters, and transmits it to the target delay digital frequency storage module to realize the distance modulation of the simulated target; calculates the frequency of the test radar signal according to the frequency of the broadband local oscillator module and the output of the instantaneous frequency measurement module, generates the Doppler frequency shift of the simulated target in real time and transmits it to the Doppler signal generation module to realize the Doppler modulation of the simulated target signal; generates the control parameters of the signal amplitude modulation and transmits them to the signal amplitude and broadband power amplifier module to realize the accurate simulation of the target signal amplitude; and controls the corresponding modules in real time.

The hypersonic wide-band radio frequency target simulation system of the present invention filters and low-noise linearly amplifies the received radar signal through a radar signal receiving frequency conversion module, mixes it with the local oscillator signal generated by a broadband local oscillator module to obtain an intermediate frequency signal, and outputs it to a target delay digital frequency storage module. The time delay value of the target is read in a control module to achieve the distance change simulation of the hypersonic moving target; then, Doppler frequency shift modulation information is added through a Doppler signal generation module, and the Doppler frequency shift value is also read from the control module to achieve the speed simulation of the hypersonic radio frequency target; finally, the control module calculates the attenuation value of the target at the current distance in real time, and realizes the accurate simulation of the target signal amplitude through the signal amplitude and broadband power amplifier module; the instantaneous frequency measurement module measures the frequency of the radar signal in real time and accurately, and provides the target delay digital frequency storage module and the Doppler signal generation module with an accurate test radar radiation signal frequency through the control module, so as to achieve the coherence of the simulated hypersonic radio frequency target signal and the test radar signal.

The key to simulating and generating a hypersonic radio frequency simulated target signal of the present invention lies in accurately controlling the delay distance change, Doppler frequency shift and signal amplitude change characteristics of the radio frequency simulated target signal. The purpose of the delay distance change is to simulate the change of the displacement of the moving target, the purpose of adding the Doppler frequency shift (phase and frequency change) to the simulated radio frequency signal is to simulate the Doppler effect of a real high-speed moving target, and the purpose of the signal amplitude change is to simulate the change of the signal energy received by the radar when the target is at different distances.

(1) Target distance simulation

In the system of the present invention, the distance at which the simulated radar echo appears on the radar screen must be strictly controlled in order to provide true value data for the radar. To this end, the distance of the target must be delayed with high precision, and the distance delay can be equivalent to the time delay in this system. The implementation method is as follows: the purpose of the radar signal receiving frequency conversion module is to output the intermediate frequency signal (which is an analog signal), and the purpose of mixing the tested radar signal and reducing it to the intermediate frequency signal is to facilitate subsequent processing. The target delay digital frequency storage module performs digital sampling on the intermediate frequency signal and converts it into a digital signal (the purpose of converting it to a digital signal is to accurately control the delay time). After the analog signal is converted to a digital signal, the digital signal is sent to the time delay circuit, and the envelope of the radar pulse signal is extracted. The rising edge signal is used as the detection pulse reference pulse. Under the synchronization of the detection pulse of the tested radar transmitting signal, the target delay digital frequency storage module reads the intermediate frequency transmission pulse stored in the digital RF memory according to the delay value τn of the simulated target calculated by the control module, and accurately simulates the target echo corresponding to different delay values. The control module calculates the next appearance distance of the simulated target according to the movement speed and time difference of the simulated target and converts it into the delay time τn.

(2) Target Doppler shift simulation

In addition to the distance delay of the target, the target echo information needs to be Doppler modulated and the Doppler frequency shift needs to be added in high speed and real time to achieve the hypersonic speed simulation. The implementation method is: the output signal of the target delay digital frequency storage module is the intermediate frequency digital signal with the delay value (distance modulation), and the Doppler signal generation module first performs I/Q orthogonal extraction on the intermediate frequency digital signal to form an I intermediate frequency digital signal and a Q intermediate frequency digital signal; as shown in Figure 3, the control module calculates the required Doppler signal frequency according to the set simulated target speed and the carrier frequency of the tested radar signal, generates a frequency control word, and controls the direct digital frequency synthesizer to generate an orthogonal I Doppler signal and a Q Doppler signal; the Doppler signal generation module then performs orthogonal mixing on the I intermediate frequency digital signal, the Q intermediate frequency digital signal and the I Doppler signal, the Q Doppler signal, and the final output is the echo intermediate frequency signal after Doppler frequency modulation.

The Doppler modulation circuit is controlled by the signal processing circuit, and the Doppler frequency modulation signal output by the signal processing circuit is up-converted to the center frequency of 1.5GHz as the signal amplitude and the local oscillator signal of the broadband power amplifier module. The Doppler frequency shift range is -0.5MHz to 0.5MHz, which corresponds to the simulation of a moving target with a relative radial velocity of Mach 13 when the radar operating frequency is 18GHz. The principle block diagram is shown in Figure 4. In the two frequency conversion processes of the Doppler modulation circuit, a filter circuit design is added after the two frequency conversions to ensure that the spurious is less than -50dBc.

(3) Target strength simulation

In order to simulate the strength of the target echo signal, the pulse signal strength of the target echo is calculated according to the technical parameters of the tested radar, the radar cross-sectional area of the simulated target, the distance from the target to the radar, the target amplitude fluctuation characteristics and other factors that affect the strength of the simulated RF target signal. According to the strength of the RF channel output signal and the maximum effective radiated power of this system, the attenuation value required to control the output signal amplitude is calculated, and the attenuator in the RF channel is controlled to make the echo signal strength reaching the receiving antenna of the tested radar equal to the calculated value. This RF target signal simulation method can realistically simulate coherent and non-coherent target echo signals including pulse compression, frequency agility and pulse Doppler radar.

The simulated target intermediate frequency signal output by the Doppler signal generation module has been range modulated and Doppler modulated. The signal amplitude and broadband power amplifier module mixes this intermediate frequency signal with the local oscillator signal of the broadband local oscillator module to obtain the same frequency as the radar signal under test, and then amplifies the power of this signal and transmits it to generate a hypersonic RF target signal, which is received by the radar. The control module calculates the attenuation value of the target at the current distance in real time based on the initial distance and initial attenuation of the simulated target, and controls the programmable attenuator of the signal amplitude and broadband power amplifier module to achieve accurate simulation of the target signal amplitude.

In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims (4)

1. A hypersonic broadband radio frequency target simulation system, comprising: the system comprises a radar signal receiving frequency conversion module, a target delay digital frequency storage module, a Doppler signal generation module, an instantaneous frequency measurement module, a signal amplitude and broadband power amplification module, a broadband local oscillation module and a control module; wherein,

The radar signal receiving frequency conversion module is used for filtering and linearly amplifying the received radar signal with low noise, mixing the radar signal with a local oscillation signal generated by the broadband local oscillation module to obtain an intermediate frequency signal, outputting the intermediate frequency signal to the target delay digital frequency storage module, and reading the time delay value of the target in the control module to realize the range change simulation of the hypersonic moving target; then adding Doppler frequency shift modulation information through a Doppler signal generation module, and reading Doppler frequency shift values from a control module to realize the speed simulation of the hypersonic radio frequency target; finally, calculating an attenuation value of the target at the current distance in real time by a control module, and realizing accurate simulation of the target signal amplitude through a signal amplitude and broadband power amplification module; the instantaneous frequency measurement module accurately measures the frequency of a radar signal in real time, provides accurate frequency of a tested radar radiation signal for the target delay digital frequency storage module and the Doppler signal generation module through the control module, and realizes the intermingling of an analog hypersonic radio frequency target signal and the tested radar signal;

The radar signal receiving frequency conversion module is used for receiving a radar radiation signal, carrying out amplitude adjustment and low-noise amplification on the received radar radiation signal, mixing the radar radiation signal with a local oscillation signal of the broadband local oscillation module to a frequency band required by digital frequency storage, and outputting the frequency band to the target delay digital frequency storage module;

the target delay digital frequency storage module is used for carrying out distance delay on the target and simulating the occurrence distance of the moving target under different radar antenna scanning periods; according to the position of the simulation target, the control module calculates the time delay value of the echo signal of the simulation target relative to the transmission pulse of the tested radar; under the synchronization of detection pulses of the detected signals of the radar to be tested, the control module reads corresponding intermediate frequency pulse signals stored in the digital radio frequency memory according to the time delay value, and simulates each target echo corresponding to different distances;

The Doppler signal generation module is used for carrying out Doppler modulation on the echo information of the target; the control module calculates the required Doppler signal frequency according to the target speed and the tested radar signal carrier frequency, and controls the direct digital frequency synthesizer to generate two orthogonal Doppler signals; the intermediate frequency digital signal which is output by the target delay digital frequency storage module and is subjected to distance modulation is subjected to I/Q quadrature decimator to form a quadrature signal; carrying out quadrature mixing on the I/Q two paths of intermediate frequency digital signals and two paths of orthogonal Doppler signals generated by a direct digital frequency synthesizer, and finally outputting the signals to be echo intermediate frequency signals after Doppler frequency modulation;

the instantaneous frequency measurement module is used for accurately measuring the signal frequency output by the radar signal receiving and frequency conversion module; the control module calculates the frequency of the radar radiation signal to be tested according to the frequency of the broadband local oscillation module and the output of the instantaneous frequency measurement module so as to calculate the Doppler frequency of the simulation target;

The signal amplitude and broadband power amplification module is used for realizing the modulation of the amplitude of a target signal, recovering an analog target intermediate frequency signal output by the range delay and Doppler modulation to the original signal frequency of a tested radar, amplifying the analog target signal to a required power level and transmitting the amplified analog target signal to generate a hypersonic radio frequency target signal, and receiving the hypersonic radio frequency target signal by the radar; the control module calculates an attenuation value of the target at the current distance in real time according to the initial distance and the initial attenuation amount of the simulation target, and controls the program-controlled attenuator to realize accurate simulation of the target signal amplitude;

The control module generates a current time delay value of the simulation target in real time according to the tested radar and the simulation target parameters and transmits the current time delay value to the target time delay digital frequency storage module so as to realize the distance modulation of the simulation target; calculating the frequency of a tested radar signal according to the frequency of the broadband local oscillation module and the output of the instantaneous frequency measurement module, generating the Doppler frequency shift of the analog target in real time, and transmitting the Doppler frequency shift to the Doppler signal generation module to realize Doppler modulation of the analog target signal; the control parameters for generating signal amplitude modulation are transmitted to the signal amplitude and broadband power amplifier module, so that the accurate simulation of the target signal amplitude is realized; and the corresponding modules are controlled in real time.

2. The hypersonic broadband radio frequency target simulation system of claim 1, wherein the broadband local oscillator module is configured to generate a mixing local oscillator signal required by the receiving down-conversion circuit and the transmitting up-conversion circuit according to an operating frequency of the radar signal under test.

3. The hypersonic broadband radio frequency target simulation system according to claim 1, wherein the signal amplitude and broadband power amplifier module modulates the target signal amplitude by a high-speed radio frequency controlled attenuator.

4. The hypersonic broadband radio frequency target simulation system of claim 3, wherein the doppler modulation is controlled by a signal processing circuit, and the doppler frequency modulation signal output by the signal processing circuit is up-converted to a center frequency of 1.5GHz as a local oscillation signal of the signal amplitude and broadband power amplifier module.