Wideband target radar echo simulation device and method based on single array element antenna

Abstract

The invention relates to a broadband target radar echo simulation device and method based on a single array element antenna. The simulation device comprises a lifting platform; the transmitting and receiving antenna unit is used for receiving radar radiation signals and transmitting simulated target echo signals, and the transmitting and receiving antenna unit is arranged at the top end of the lifting platform and moves continuously along with the lifting platform so as to simulate the pitch angle of the spatial position of the ballistic target relative to the radar; and the echo simulation module is used for performing down-conversion processing on the radar radiation signal received by the transceiving antenna unit, extracting a baseband signal, modulating the baseband signal, performing up-conversion processing, obtaining the simulation target echo signal, and sending the simulation target echo signal to the transceiving antenna unit. According to the invention, radar radiation signals can be detected and forwarded in an ultra-large frequency range, radar echo signals of multiple frequency bands can be simulated, and the radar frequency agility working mode can be adapted.

Description

Technical Field

[0001] The present invention relates to the technical field of radar echo simulation and emulation, and in particular to a wide-band target radar echo simulation device and method based on a single-element antenna. Background Art

[0002] Using radar to detect ballistic targets is an important part of air defense and anti-missile defense. Therefore, during the design, development and production of radar, it is necessary to verify and evaluate the radar's ability to search, capture and track ballistic targets. In field experiments, it is also necessary to verify the detection effect of radar on ballistic targets under certain environments. However, if the method of launching at real ballistic targets is adopted, it will consume a lot of time, financial resources and material resources, and some scenarios are difficult to verify through real launch. Therefore, a ballistic target echo signal simulation device is needed to flexibly simulate the radar echo signal of ballistic targets in various scenarios, so as to conveniently and quickly evaluate the detection effect of radar on ballistic targets in various electromagnetic environments and various ballistic scenarios. On the basis of greatly reducing the experimental cost, the test efficiency is significantly improved.

[0003] The existing echo simulation devices in China have the following defects:

[0004] 1. It basically does not support working in high and low temperature environments, which greatly limits the choice of region and time for implementing the experiment. It is not conducive to conducting experiments across the entire territory of my country and in summer and winter, affecting the evaluation of radar detection effects in extreme environments and the efficiency of project implementation.

[0005] 2. Most of them arrange multiple antenna units at different heights on the bracket and the base, and select a certain antenna unit through the RF electronic switch according to the elevation angle of the simulated target relative to the radar to simulate targets with different elevation angles; among them, the method of arranging multiple antenna units at different heights and opening them in time-sharing through the RF switch requires multiple antenna array elements and RF electronic switches, multiple amplitude and phase stabilizing cables for connection, and the antenna array structure, wiring and control are complex, as well as the on-site arrangement is inconvenient; in addition, the selection of antenna array elements through the RF electronic switch causes discontinuity and inaccuracy in the pitch simulation of ballistic targets.

[0006] 3. When using simulated echo signals, DDS is used to directly generate or store and forward radar radiation signals. This method uses DDS to directly generate radar target echoes, but it requires accurate knowledge of the parameters of the radar radiation signal and cannot effectively simulate target echo signals in complex battlefield environments.

[0007] At present, there is no public information on the existing echo simulation devices in China that have the ability to detect and forward radar radiation signals within an ultra-large frequency range (2 to 18 GHz), simulate radar echo signals in multiple frequency bands, and adapt to the radar agile frequency operation mode. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a wide-band target radar echo simulation device and method based on a single-element antenna, which can detect and forward radar radiation signals within an ultra-large frequency range, simulate radar echo signals of multiple frequency bands, and adapt to the radar agile frequency operation mode.

[0009] The technical solution adopted by the present invention to solve the technical problem is: to provide a wide-band target radar echo simulation device based on a single-element antenna, comprising:

[0010] A lifting platform, wherein the lifting platform realizes stepless adjustment of the lifting height through a servo motor;

[0011] The transceiver antenna unit is used to receive radar radiation signals and transmit simulated target echo signals. The transceiver antenna unit is a single antenna array element, which is placed on the top of the lifting platform and moves continuously with it to simulate the pitch angle of the spatial position of the ballistic target relative to the radar;

[0012] The echo simulation module is used to extract the baseband signal after down-converting the radar radiation signal received by the transceiver antenna unit, and then modulate the baseband signal and perform up-conversion processing to obtain the simulated target echo signal and send it to the transceiver antenna unit.

[0013] Furthermore, the echo simulation module includes:

[0014] A frequency conversion unit, configured to down-convert the radar radiation signal received by the antenna unit to an intermediate frequency to obtain a first intermediate frequency signal, and up-convert the second intermediate frequency signal generated by the signal processing unit to a radio frequency to obtain the simulated target echo signal;

[0015] The signal processing unit is used to perform digital sampling and digital down-conversion processing on the first intermediate frequency signal in sequence to obtain a baseband signal, and then modulate the baseband signal to simulate the distance and speed of the ballistic target, obtain a second intermediate frequency signal and send it to the frequency conversion unit.

[0016] Furthermore, the frequency conversion unit is also used to control the radiation power of the generated simulated target echo signal according to the distance between the ballistic target and the radar.

[0017] Furthermore, the frequency conversion unit includes an instantaneous frequency measuring machine, which is used to perform instantaneous frequency measurement on the received signal and then directly guide the frequency synthesizer to perform frequency conversion.

[0018] Furthermore, the echo simulation module also includes a terminal control unit, which is used to calculate the height of the transceiver antenna unit according to the spatial position of the ballistic target relative to the pitch angle of the radar, and then control the lifting platform to lift the transceiver antenna unit to this height.

[0019] Furthermore, the signal processing unit includes:

[0020] An analog-to-digital conversion module, used for digitally sampling the first intermediate frequency signal to obtain a first processed signal;

[0021] A digital down-conversion module, used for performing digital down-conversion processing on the first processed signal to obtain a baseband signal;

[0022] A modulation module is used to sequentially perform time delay modulation, Doppler modulation and amplitude modulation on the baseband signal to obtain a modulated signal;

[0023] A digital up-conversion module, used for performing digital up-conversion processing on the modulated signal to obtain a second processed signal;

[0024] The digital-to-analog conversion module is used to convert the second processed signal into an analog signal to obtain a second intermediate frequency signal.

[0025] The present invention also provides a method for simulating wide-band target radar echo based on a single-element antenna, which is applied to the above-mentioned device and comprises the following steps:

[0026] According to the ballistic parameters, the target ballistic trajectory is calculated using the kinematic equation, and then the spatial position of the ballistic target is obtained;

[0027] Calculate the target radiation power of the simulated target echo signal according to the distance of the ballistic target's spatial position relative to the radar;

[0028] The target height of the transceiver antenna unit is calculated according to the pitch angle of the ballistic target relative to the radar, and then the lifting platform is controlled to lift the transceiver antenna unit to the height;

[0029] The radar radiation signal is received by using a transceiver antenna unit at the target height, the received radar radiation signal is down-converted and then a baseband signal is extracted, and then the baseband signal is modulated and then up-converted to obtain a simulated target echo signal and adjust its radiation power to the target radiation power;

[0030] The simulated target echo signal is transmitted through the transceiver antenna unit.

[0031] Furthermore, the trajectory parameters include a starting point, a landing point, a trajectory mode and a discrete time interval.

[0032] Furthermore, the extracting the baseband signal after performing down-conversion processing on the received radar radiation signal, and then modulating the baseband signal and performing up-conversion processing, comprises:

[0033] Down-converting the received radar radiation signal to an intermediate frequency and controlling its level to obtain a first intermediate frequency signal;

[0034] Performing digital sampling and digital down-conversion processing on the first intermediate frequency signal in sequence to obtain a baseband signal;

[0035] Modulating the baseband signal to simulate the distance and speed of the ballistic target to obtain a modulated signal;

[0036] Performing digital up-conversion processing and digital-to-analog conversion on the modulated signal in sequence to obtain a second intermediate frequency signal;

[0037] The second intermediate frequency signal is up-converted to a radio frequency to obtain a simulated target echo signal.

[0038] Furthermore, the modulating the baseband signal includes sequentially performing time delay modulation, Doppler modulation and amplitude modulation on the baseband signal.

[0039] Beneficial Effects

[0040] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0041] (1) The present invention adopts a high and low temperature servo motor drive to lift the antenna array element fixed on the top of the lifting rod to a specified height, and realizes real-time and accurate control of the position and speed of the lifting process according to a predetermined strategy, so as to realize approximately continuous movement of the antenna array element, simulate the pitch change of the ballistic target in real time and with high precision, and flexibly and conveniently simulate targets with different elevation angles without changing the hardware; the present invention can work in harsh high and low temperature environments, has high environmental adaptability, accurate position control, fast lifting speed, simple antenna array element structure and wiring, and avoids the problem that the traditional echo simulation device has poor environmental adaptability and cannot work in harsh high and low temperature environments, and avoids the problems of slow movement, poor real-time performance, poor stability and low precision when the traditional stepping motor drives the antenna array element to move along the guide rail to simulate the elevation change of the ballistic target, and also avoids the problems of discontinuity and large error when multiple fixed antenna array elements are controlled by electronic switches to simulate the pitch of the ballistic target, and the complex structure, wiring and control caused by multiple array element settings;

[0042] (2) The present invention has a radar radiation signal reconnaissance function, uses a DRFM method to process radar radiation signals, and performs time delay and phase modulation on the baseband signal after the radiation signal is down-converted through an algorithm and a digital processing device, so as to simulate the distance and Doppler information of the target in real time and accurately, and control the radiation power according to the distance between the simulated target and the radar, thereby greatly enhancing the authenticity of the target simulation, and avoiding the problem that the method of using DDS to directly generate radar target echoes requires accurate mastery of the parameters of the radar radiation signal and cannot effectively simulate the target echo signal in a complex battlefield environment; the present invention uses a multi-phase filter to complete the filtering and extraction process in the digital down-conversion, thereby reducing the requirements for the processing clock; this embodiment has an instantaneous frequency measurement function, can perform instantaneous frequency measurement on the input signal, and perform frequency synthesis guidance, so as to realize the reconnaissance and forwarding of radar radiation signals in a large frequency range, and avoid the problem that the simulation device can only simulate a single-band radar echo signal, and cannot work when the radar switches the frequency point or changes the frequency quickly;

[0043] (3) The present invention realizes the control of the device, data display and automatic generation of ballistic data in the radar station center coordinate system through the host computer software; the host computer software can calculate the pitch angle of the spatial position of the ballistic target trajectory relative to the radar in the radar station center coordinate system based on the ballistic trajectory file generated by itself or transmitted from the outside, and automatically calculate the height of the antenna array element and the servo motor control word according to the test radar position. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of an experimental scenario of an implementation mode of the present invention;

[0045] Figure 2 is a structural block diagram of an embodiment of the present invention;

[0046] Figure 3 is a principle block diagram of an antenna unit according to an embodiment of the present invention;

[0047] Figure 4 is a principle block diagram of a frequency conversion unit according to an embodiment of the present invention;

[0048] Figure 5 is a principle block diagram of a signal processing unit in an embodiment of the present invention;

[0049] Figure 6 It is a block diagram of the digital down-conversion principle of a signal processing unit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0051] The first embodiment of the present invention relates to a wide-band target radar echo simulation device based on a single-element antenna, such as Figure 1 As shown, it includes a lifting platform, a transceiver antenna unit and an echo simulation module.

[0052] Among them, the echo simulation module includes a frequency conversion unit, a signal processing unit and a terminal control unit. The frequency conversion unit is electrically connected to the antenna unit and the signal processing unit respectively, and the signal processing unit is electrically connected to the frequency conversion unit and the terminal control unit respectively. The antenna unit receives the radar radiation signal and transmits it to the frequency conversion unit and radiates the simulated target echo transmitted by the frequency conversion unit; the frequency conversion unit receives the radio frequency signal transmitted by the antenna unit, down-converts it to an intermediate frequency signal and controls its level, and transmits it to the signal processing unit; receives the intermediate frequency signal transmitted by the signal processing unit, up-converts it to radio frequency and controls its level, transmits it to the transceiver antenna unit, and provides a digital processing clock signal for the signal processing unit. The signal processing unit obtains a baseband signal by digitally sampling the intermediate frequency signal transmitted by the frequency conversion unit and performing digital down-conversion processing; performs time delay modulation and Doppler frequency modulation on the baseband signal to simulate the distance and speed of the target respectively; performs digital up-conversion processing on the modulated baseband signal to obtain a digital intermediate frequency signal simulating the target echo, and transmits it to the frequency conversion unit.

[0053] The transceiver antenna unit of this embodiment adopts a single antenna element to radiate and receive radio frequency signals, and the antenna element structure and wiring are simple. The antenna unit is driven by a high and low temperature servo motor, and uses a high and low temperature resistant battery and a portable PC. It has high adaptability to the experimental site environment, and experiments can be carried out in most geographical locations and time ranges in my country. The antenna element is fixed on the top of the lifting platform, and the driver is controlled by the instructions of the host computer software. The host computer software can receive the simulated target trajectory transmitted from the outside world and perform interpolation fitting and other processing on it, control the rotation of the motor, and thus control the lifting platform to lift the antenna to a specified height according to a predetermined strategy. The use of a single antenna element can truly and effectively meet the needs of target simulation, and greatly reduces the complexity of antenna structure, wiring and control compared to multi-element solutions.

[0054] The frequency conversion unit has the function of detecting and forwarding radar radiation signals in an ultra-large frequency range (2 to 18 GHz). It is responsible for down-converting the RF signal received by the transceiver antenna unit to the intermediate frequency, and up-converting the analog intermediate frequency signal transmitted by the signal processing unit DAC to the RF, and power amplification. The frequency conversion unit has the function of instantaneous frequency measurement, performs instantaneous frequency measurement on the input signal, and guides the frequency synthesis, which can adapt to the radar agile frequency conversion working mode. After the instantaneous frequency measurement machine measures the frequency, it directly guides the frequency synthesis to perform frequency conversion, and transmits the frequency measurement code to the signal processing unit.

[0055] The signal processing unit performs corresponding frequency precision measurement according to the frequency measurement code transmitted by the frequency conversion unit, performs accurate signal modulation output, and uses a multi-phase filter to complete the filtering and extraction / interpolation process in the digital frequency conversion. It can modulate the distance, Doppler, etc. of the received radar signal, perform amplitude modulation according to the radar equation, etc., and radiate the modulated signal through the antenna.

[0056] The host computer software of the terminal control unit can receive the motor parameters and status information that can be transmitted by the servo drive system, so as to solve the antenna height and display it. The host computer software mainly calculates the servo motor control word based on the ballistic trajectory file generated by itself or transmitted from the outside. The spatial position of the ballistic target trajectory relative to the pitch angle (θ) of the radar can be obtained in two ways: one is that the host computer software calculates the ballistic trajectory based on the ballistic parameters (starting point, landing point, ballistic mode, discrete time interval, etc.) and kinematic equations, and calculates the distance, azimuth, pitch angle and other parameters of the ballistic target in the radar station center coordinate system according to the radar position and other parameters; the other is that the host computer software reads the ballistic trajectory file transmitted from the outside, and calculates the distance, azimuth, pitch angle and other parameters of the ballistic target in the radar station center coordinate system according to the radar position and other parameters.

[0057] During operation, the antenna array elements move continuously with the lifting platform. Assume that the spatial position of the simulated ballistic target trajectory at a certain moment is at an elevation angle of θ relative to the radar, and the horizontal distance between the tested radar and the lifting platform is R. a , the height of the tested radar is H radar , then the height H of the antenna element should be: H = R a tan(θ)+H radar .

[0058] The height of the antenna array element is obtained by polynomial fitting (obtaining polynomial coefficients that meet the requirements through iteration), and the control word of the servo motor is calculated based on the control requirements and performance parameters of the servo motor.

[0059] Without changing the hardware, ballistic targets in various scenarios can be simulated by changing the simulated target trajectory.

[0060] The following is a further description with reference to the accompanying drawings.

[0061] like Figure 1 As shown, the system in the present invention only needs a single antenna transceiver array element, which is placed on the top of the lifting platform. The lifting platform is lifted vertically and drives the servo motor according to the servo motor control word calculated according to the simulated target trajectory, and lifts the antenna fixed on the top of the lifting rod to a specified height in real time to simulate the pitch angle change of the target. The simulation device receives the radar radiation signal through the antenna transceiver array element, which is modulated and processed by the simulation device frequency conversion unit and signal processing unit, and then radiated to the test radar through the antenna transceiver array element.

[0062] like Figure 2 As shown, the frequency conversion unit is electrically connected to the antenna unit and the signal processing unit, respectively, and the signal processing unit is electrically connected to the frequency conversion unit and the terminal control unit, respectively. The antenna unit receives the radar radiation signal and transmits it to the frequency conversion unit and radiates the simulated target echo transmitted by the frequency conversion unit; the frequency conversion unit receives the radio frequency signal transmitted by the antenna unit, down-converts it to an intermediate frequency signal and controls its level, and transmits it to the signal processing unit; receives the intermediate frequency signal transmitted by the signal processing unit, up-converts it to radio frequency and controls its level, transmits it to the transceiver antenna unit, and provides a digital processing clock signal for the signal processing unit. The signal processing unit obtains a baseband signal by digitally sampling the intermediate frequency signal transmitted by the frequency conversion unit and performing digital down-conversion processing; performs time delay modulation and Doppler frequency modulation on the baseband signal to simulate the distance and speed of the target respectively; performs digital up-conversion processing on the modulated baseband signal to obtain a digital intermediate frequency signal simulating the target echo, and transmits it to the frequency conversion unit.

[0063] like Figure 3 As shown, the transceiver antenna unit of the present invention adopts a single antenna element to radiate and receive radio frequency signals, and the antenna element structure and wiring are simple. The antenna unit is driven by a high and low temperature servo motor, and uses a high and low temperature resistant battery and a portable PC. It has high adaptability to the experimental site environment, and experiments can be carried out in most geographical locations and time ranges in my country. The antenna element is fixed on the top of the lifting platform, and the driver is controlled by the instructions of the host computer software. The host computer software can receive the simulated target trajectory transmitted from the outside and perform interpolation fitting and other processing on it, control the rotation of the motor, and thus control the lifting platform to lift the antenna to a specified height according to a predetermined strategy. The use of a single antenna element can truly and effectively meet the needs of target simulation, and greatly reduces the complexity of antenna structure, wiring and control compared to multi-element solutions.

[0064] like Figure 4 As shown, according to the radar equation, in actual detection, assuming that the target scattering cross-sectional area is σ, the target echo power P received by the radar antenna is r1 for:

[0065]

[0066] Among them, P t Represents the radar's transmitting power, G t represents the radar antenna transmission gain, G r represents the receiving gain of the radar antenna, λ is the wavelength of the transmitted signal, and R is the distance between the simulated target and the radar.

[0067] When using the simulator to forward the signal, the slant distance between the simulator antenna array and the radar is R s To meet the far-field condition, assume that the radiation power of the simulator antenna array element is P ts , the antenna gain of the simulator is G ts , then the target echo power P received by the radar antenna is r2 for:

[0068]

[0069] In order to simulate the detection of targets in real scenes, the condition P should be met. r1 =P r2 . From this, we can get the simulator antenna element radiation power P ts Should be:

[0070]

[0071] In this embodiment, the distance between the simulated target and the radar and other parameters are substituted into equation (3) to obtain the radiated power of the simulator antenna array element, and the attenuator is controlled accordingly.

[0072] like Figure 5 , Figure 6 As shown, in the signal processing unit, analog-to-digital conversion (A / D sampling) is performed on the analog intermediate frequency signal, followed by digital down-conversion processing to obtain a baseband signal, and delay modulation is performed on the obtained baseband signal.

[0073] like Figure 6 As shown, the A / D output signal is digitally orthogonally transformed to obtain the baseband signal, and then the extraction and filtering are completed through the polyphase filter. Assuming that the impulse response of the digital filter is h(n), its Z transform H(z) is:

[0074]

[0075] make

[0076] Then H(z) can be transformed into

[0077]

[0078] Assume that the baseband signal after digital down-conversion is S(t), the distance between the simulated target and the radar is R, and the slant distance between the simulator antenna array element and the radar is R. sThe transmission delay caused by , the delay τ is:

[0079]

[0080] Where c is the speed of light.

[0081] The signal after delay modulation is S(t-τ).

[0082] Doppler modulation is performed on the delayed baseband signal. Assuming that the radial velocity of the simulated target is V, the Doppler frequency of the target is:

[0083] f d =2V / λ

[0084] The phase increment of the echo signal caused by the Doppler frequency can be approximated as:

[0085] Δφ=2πf d nT s

[0086] The signal after Doppler modulation is:

[0087] S′(t)=S(t-τ)exp(jΔφ)

[0088] The modulated signal is digitally up-converted to obtain a digital intermediate frequency signal, which is then transmitted to the D / A and converted into an analog intermediate frequency signal. The brief process is as follows:

[0089] S″(t)=S′(t)exp(j2πf IF mt s )

[0090] Among them, f IF is the intermediate frequency, m is the sampling point position within the pulse repetition period, t s is the sampling time interval.

[0091] The up-conversion channel of the frequency conversion unit up-converts the analog intermediate frequency signal transmitted by the DA to a radio frequency, which is radiated through the antenna unit.

[0092] The host computer software of the terminal control unit of the present invention is responsible for the control of the device, data display and the generation of ballistic data in the radar station center coordinate system. The motor parameters and status information that can be transmitted by the servo drive system can be received to solve the antenna height and display it. The host computer software mainly calculates the servo motor control word based on the ballistic trajectory file generated by itself or transmitted from the outside. The pitch angle (θ) of the spatial position of the trajectory of the ballistic target relative to the radar can be obtained in two ways: one is that the host computer software calculates the ballistic trajectory in the WGS84 coordinate system according to the ballistic parameters (starting point, landing point, ballistic mode, discrete time interval, etc.) and kinematic equations set in the software interface, and converts the ballistic trajectory in the WGS84 coordinate system to the radar station center coordinate system according to the parameters such as the radar position, so as to obtain the distance, azimuth, pitch angle and other parameters of the ballistic target in the radar station center coordinate system; one is that the host computer software reads the ballistic trajectory file transmitted from the outside, and calculates the distance, azimuth, pitch angle and other parameters of the ballistic target in the radar station center coordinate system according to the parameters such as the radar position.

[0093] During operation, the antenna array element moves continuously with the lifting platform. Assuming that the spatial position of the simulated ballistic target trajectory at a certain moment is at an elevation angle of θ relative to the radar, the height of the antenna array element should be: H = R a tan(θ)+H radar .

[0094] The height of the antenna array element is obtained by polynomial fitting (obtaining polynomial coefficients that meet the requirements through iteration), and the control word of the servo motor is calculated based on the control requirements and performance parameters of the servo motor.

[0095] Without changing the hardware, ballistic targets in various scenarios can be simulated by changing the simulated target trajectory.

[0096] The second embodiment of the present invention relates to a method for simulating wide-band target radar echoes based on a single-element antenna, which is applied to the device in the first embodiment and includes the following steps:

[0097] According to the ballistic parameters, the target ballistic trajectory is calculated using the kinematic equation, and then the spatial position of the ballistic target is obtained;

[0098] Calculate the target radiation power of the simulated target echo signal according to the distance of the ballistic target's spatial position relative to the radar;

[0099] The target height of the transceiver antenna unit is calculated according to the pitch angle of the ballistic target relative to the radar, and then the lifting platform is controlled to lift the transceiver antenna unit to the height;

[0100] Receive radar radiation signals using a transceiver antenna unit;

[0101] Down-converting the received radar radiation signal to an intermediate frequency and controlling its level to obtain a first intermediate frequency signal;

[0102] Performing digital sampling and digital down-conversion processing on the first intermediate frequency signal in sequence to obtain a baseband signal;

[0103] The baseband signal is subjected to time delay modulation, Doppler modulation and amplitude modulation in sequence to simulate the distance and speed of the ballistic target to obtain a modulated signal;

[0104] Performing digital up-conversion processing and digital-to-analog conversion on the modulated signal in sequence to obtain a second intermediate frequency signal;

[0105] Up-converting the second intermediate frequency signal to a radio frequency to obtain a simulated target echo signal and adjusting its radiation power to a target radiation power;

[0106] The simulated target echo signal is transmitted using the transceiver antenna unit at the target height.

[0107] The present embodiment is further described below in conjunction with a specific device.

[0108] like Figure 1 As shown, the system in the present invention only needs a single antenna transceiver array element, which is placed on the top of the lifting platform. The lifting platform is lifted vertically and drives the servo motor according to the servo motor control word calculated according to the simulated target trajectory, and lifts the antenna fixed on the top of the lifting rod to a specified height in real time to simulate the pitch angle change of the target. The simulation device receives the radar radiation signal through the antenna transceiver array element, which is modulated and processed by the simulation device frequency conversion unit and signal processing unit, and then radiated to the test radar through the antenna transceiver array element.

[0109] like Figure 2 As shown, the frequency conversion unit is electrically connected to the antenna unit and the signal processing unit, respectively, and the signal processing unit is electrically connected to the frequency conversion unit and the terminal control unit, respectively. The antenna unit receives the radar radiation signal and transmits it to the frequency conversion unit and radiates the simulated target echo transmitted by the frequency conversion unit; the frequency conversion unit receives the radio frequency signal transmitted by the antenna unit, down-converts it to an intermediate frequency signal and controls its level, and transmits it to the signal processing unit; receives the intermediate frequency signal transmitted by the signal processing unit, up-converts it to radio frequency and controls its level, transmits it to the transceiver antenna unit, and provides a digital processing clock signal for the signal processing unit. The signal processing unit obtains a baseband signal by digitally sampling the intermediate frequency signal transmitted by the frequency conversion unit and performing digital down-conversion processing; performs time delay modulation and Doppler frequency modulation on the baseband signal to simulate the distance and speed of the target respectively; performs digital up-conversion processing on the modulated baseband signal to obtain a digital intermediate frequency signal simulating the target echo, and transmits it to the frequency conversion unit.

[0110] like Figure 3As shown, the transceiver antenna unit of the present invention adopts a single antenna element to radiate and receive radio frequency signals, and the antenna element structure and wiring are simple. The antenna unit is driven by a high and low temperature servo motor, and uses a high and low temperature resistant battery and a portable PC. It has high adaptability to the experimental site environment, and experiments can be carried out in most geographical locations and time ranges in my country. The antenna element is fixed on the top of the lifting platform, and the driver is controlled by the instructions of the host computer software. The host computer software can receive the simulated target trajectory transmitted from the outside and perform interpolation fitting and other processing on it, control the rotation of the motor, and thus control the lifting platform to lift the antenna to a specified height according to a predetermined strategy. The use of a single antenna element can truly and effectively meet the needs of target simulation, and greatly reduces the complexity of antenna structure, wiring and control compared to multi-element solutions.

[0111] like Figure 4 As shown, according to the radar equation, in actual detection, assuming that the target scattering cross-sectional area is σ, the target echo power P received by the radar antenna is r1 for:

[0112]

[0113] Among them, P t Represents the radar's transmitting power, G t represents the radar antenna transmission gain, G r represents the receiving gain of the radar antenna, λ is the wavelength of the transmitted signal, and R is the distance between the simulated target and the radar.

[0114] When using the simulator to forward the signal, the slant distance between the simulator antenna array and the radar is R s To meet the far-field condition, assume that the radiation power of the simulator antenna array element is P ts , the antenna gain of the simulator is G ts , then the target echo power P received by the radar antenna is r2 for:

[0115]

[0116] In order to simulate the detection of targets in real scenes, the condition P should be met. r1 =P r2 . From this, we can get the simulator antenna element radiation power P ts Should be:

[0117]

[0118] In this embodiment, the distance between the simulated target and the radar and other parameters are substituted into equation (3) to obtain the radiated power of the simulator antenna array element, and the attenuator is controlled accordingly.

[0119] like Figure 5 , Figure 6As shown, in the signal processing unit, analog-to-digital conversion (A / D sampling) is performed on the analog intermediate frequency signal, followed by digital down-conversion processing to obtain a baseband signal, and delay modulation is performed on the obtained baseband signal.

[0120] like Figure 6 As shown, the A / D output signal is digitally orthogonally transformed to obtain the baseband signal, and then the extraction and filtering are completed through the polyphase filter. Assuming that the impulse response of the digital filter is h(n), its Z transform H(z) is:

[0121]

[0122] make

[0123] Then H(z) can be transformed into

[0124]

[0125] Assume that the baseband signal after digital down-conversion is S(t), the distance between the simulated target and the radar is R, and the slant distance between the simulator antenna array element and the radar is R. s The transmission delay caused by , the delay τ is:

[0126]

[0127] Where c is the speed of light.

[0128] The signal after delay modulation is S(t-τ).

[0129] Doppler modulation is performed on the delayed baseband signal. Assuming that the radial velocity of the simulated target is V, the Doppler frequency of the target is:

[0130] f d =2V / λ

[0131] The phase increment of the echo signal caused by the Doppler frequency can be approximated as:

[0132] Δφ=2πf d nT s

[0133] The signal after Doppler modulation is:

[0134] S′(t)=S(t-τ)exp(jΔφ)

[0135] The modulated signal is digitally up-converted to obtain a digital intermediate frequency signal, which is then transmitted to the D / A and converted into an analog intermediate frequency signal. The brief process is as follows:

[0136] S″(t)=S′(t)exp(j2πf IF mt s )

[0137] Among them, f IF is the intermediate frequency, m is the sampling point position within the pulse repetition period, t s is the sampling time interval.

[0138] The up-conversion channel of the frequency conversion unit up-converts the analog intermediate frequency signal transmitted by the DA to a radio frequency, which is radiated through the antenna unit.

[0139] The host computer software of the terminal control unit of the present invention is responsible for the control of the device, data display and the generation of ballistic data in the radar station center coordinate system. The motor parameters and status information that can be transmitted by the servo drive system can be received to solve the antenna height and display it. The host computer software mainly calculates the servo motor control word based on the ballistic trajectory file generated by itself or transmitted from the outside. The pitch angle (θ) of the spatial position of the trajectory of the ballistic target relative to the radar can be obtained in two ways: one is that the host computer software calculates the ballistic trajectory in the WGS84 coordinate system according to the ballistic parameters (starting point, landing point, ballistic mode, discrete time interval, etc.) and kinematic equations set in the software interface, and converts the ballistic trajectory in the WGS84 coordinate system to the radar station center coordinate system according to the parameters such as the radar position, so as to obtain the distance, azimuth, pitch angle and other parameters of the ballistic target in the radar station center coordinate system; one is that the host computer software reads the ballistic trajectory file transmitted from the outside, and calculates the distance, azimuth, pitch angle and other parameters of the ballistic target in the radar station center coordinate system according to the parameters such as the radar position.

[0140] During operation, the antenna array element moves continuously with the lifting platform. Assuming that the spatial position of the simulated ballistic target trajectory at a certain moment is at an elevation angle of θ relative to the radar, the height of the antenna array element should be: H = R a tan(θ)+H radar .

[0141] The height of the antenna array element is obtained by polynomial fitting (obtaining polynomial coefficients that meet the requirements through iteration), and the control word of the servo motor is calculated based on the control requirements and performance parameters of the servo motor.

[0142] Without changing the hardware, ballistic targets in various scenarios can be simulated by changing the simulated target trajectory.

Claims

1. A wide-band target radar echo simulation device based on a single-element antenna, characterized in that: include: A lifting platform, wherein the lifting platform realizes stepless adjustment of the lifting height through a servo motor; A transceiver antenna unit, used to receive radar radiation signals and transmit simulated target echo signals. The transceiver antenna unit is a single antenna array element, which is placed on the top of the lifting platform and moves continuously with it to simulate the pitch angle of the spatial position of the ballistic target relative to the radar; The echo simulation module is used to extract the baseband signal after down-converting the radar radiation signal received by the transceiver antenna unit, and then modulate the baseband signal and perform up-conversion processing to obtain the simulated target echo signal and send it to the transceiver antenna unit.

2. The device according to claim 1, characterized in that The echo simulation module comprises: The frequency conversion unit is used to down-convert the radar radiation signal received by the antenna unit to an intermediate frequency to obtain a first intermediate frequency signal, and up-convert the second intermediate frequency signal generated by the signal processing unit to a radio frequency to obtain the simulated target echo signal; the signal processing unit is used to perform digital sampling and digital down-conversion processing on the first intermediate frequency signal in sequence to obtain a baseband signal, and then modulate the baseband signal to simulate the distance and speed of the ballistic target, obtain a second intermediate frequency signal and send it to the frequency conversion unit.

3. The device according to claim 2, characterized in that The frequency conversion unit is also used to control the radiation power of the generated simulated target echo signal according to the distance between the ballistic target and the radar.

4. The device according to claim 2, characterized in that The frequency conversion unit includes an instantaneous frequency measuring machine, which is used to perform instantaneous frequency measurement on the received signal and then directly guide the frequency synthesizer to perform frequency conversion.

5. The device according to claim 2, characterized in that The echo simulation module also includes a terminal control unit, which is used to calculate the height of the transceiver antenna unit according to the pitch angle of the ballistic target's spatial position relative to the radar, and then control the lifting platform to lift the transceiver antenna unit to the height.

6. The device according to claim 2, characterized in that The signal processing unit comprises: An analog-to-digital conversion module, used for digitally sampling the first intermediate frequency signal to obtain a first processed signal; A digital down-conversion module, used for performing digital down-conversion processing on the first processed signal to obtain a baseband signal; A modulation module is used to sequentially perform time delay modulation, Doppler modulation and amplitude modulation on the baseband signal to obtain a modulated signal; A digital up-conversion module, used for performing digital up-conversion processing on the modulated signal to obtain a second processed signal; The digital-to-analog conversion module is used to convert the second processed signal into an analog signal to obtain a second intermediate frequency signal.

7. A method for simulating wide-band target radar echo based on a single-element antenna, characterized in that: Applicable to the device as claimed in claims 1-6, comprising the following steps: According to the ballistic parameters, the target ballistic trajectory is calculated using the kinematic equation, and then the spatial position of the ballistic target is obtained; Calculate the target radiation power of the simulated target echo signal according to the distance of the ballistic target's spatial position relative to the radar; The target height of the transceiver antenna unit is calculated according to the pitch angle of the ballistic target relative to the radar, and then the lifting platform is controlled to lift the transceiver antenna unit to the height; The radar radiation signal is received by using a transceiver antenna unit at the target height, the received radar radiation signal is down-converted and then a baseband signal is extracted, and then the baseband signal is modulated and then up-converted to obtain a simulated target echo signal and adjust its radiation power to the target radiation power; The simulated target echo signal is transmitted through the transceiver antenna unit.

8. The method according to claim 7, characterized in that The trajectory parameters include a starting point, a landing point, a trajectory mode and a discrete time interval.

9. The method according to claim 7, characterized in that: The method of extracting a baseband signal after performing down-conversion processing on the received radar radiation signal, and then modulating the baseband signal and performing up-conversion processing comprises: Down-converting the received radar radiation signal to an intermediate frequency and controlling its level to obtain a first intermediate frequency signal; Performing digital sampling and digital down-conversion processing on the first intermediate frequency signal in sequence to obtain a baseband signal; Modulating the baseband signal to simulate the distance and speed of the ballistic target to obtain a modulated signal; Performing digital up-conversion processing and digital-to-analog conversion on the modulated signal in sequence to obtain a second intermediate frequency signal; The second intermediate frequency signal is up-converted to a radio frequency to obtain a simulated target echo signal.

10. The method according to claim 9, characterized in that The modulating the baseband signal includes sequentially performing time delay modulation, Doppler modulation and amplitude modulation on the baseband signal.

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