A method for simulating airborne fire control radar signals based on UAV

Abstract

The present invention discloses a method for simulating airborne fire control radar signals based on a drone. The method is implemented based on an airborne fire control radar simulation device installed on the drone. The method comprises the following steps: setting an airborne fire control radar transmit signal and establishing radar transmit signal parameters according to the detection mode of the fighter jet's onboard fire control radar; setting a maneuvering scenario of the fighter jet to be simulated and establishing a corresponding maneuvering scenario description according to the fighter jet's maneuvering mode; calculating the corresponding attitude and speed characteristics of the fighter jet at a certain moment based on the set maneuvering scenario; calculating the deviations of multiple parameters of the simulated airborne fire control radar of the drone under the maneuvering scenario based on the obtained attitude and speed characteristics; and adjusting and compensating the deviations of the radar transmit signal parameters based on the current UAV airborne radar transmit waveform based on the above results, thereby achieving realistic simulation of the airborne fire control radar radiation signal under the maneuvering scenario. The present invention can achieve the purpose of realistically simulating the airborne fire control radar signal of the fighter jet under the maneuvering state.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar simulation, and in particular relates to a method for simulating airborne fire control radar signals based on an unmanned aerial vehicle (UAV). Background Art

[0002] Airborne fire control radar (AFCR) refers to an airborne radar used to search, intercept, and track aerial targets, providing the data necessary for weapon aiming, firing, and guidance. A AFCR is an essential electronic component for fighter jets, capable of detecting and tracking targets, providing information such as their location and velocity, and guiding the fire control system to strike ground, sea, and air targets. With the continuous development and application of AFCR, various types of radar reconnaissance and jamming equipment are also being developed to weaken the combat capabilities of enemy fighter jets' AFCR radars. Currently, the most critical issue in testing the performance of radar reconnaissance and jamming equipment is how to quickly and economically simulate enemy airborne fire control radars and conduct reconnaissance and jamming performance tests in a realistic electromagnetic environment.

[0003] There are currently two commonly used methods for simulating enemy airborne fire control radars: the first method is to directly use fighter jets to load fire control radars. However, this method is limited by the special management methods and high operating costs of fighter jets. It is relatively complicated to implement, has low cost-effectiveness, and is difficult to promote on a large scale; the second method is to use airborne radar simulators for testing. Traditional airborne radar simulators can be installed on drones. In principle, airborne fire control radar signals can be directly generated using airborne radar simulators. However, due to the large gap in the maneuverability of drones compared to fighter jets at this stage, traditional methods ignore the characteristic differences between the two in maneuverable states, which will cause the radar signals received by radar reconnaissance and jamming equipment to deviate from the actual airborne fire control radar signals. Therefore, this method also has certain limitations. Summary of the Invention

[0004] To solve the above problems, the purpose of the present invention is to provide an airborne fire control radar signal simulation method based on a UAV, which uses a UAV instead of a fighter jet as the carrier of the airborne fire control radar, and can eliminate the influence of the maneuvering state difference on the radar signal. When taking off and flying, it can achieve the purpose of realistically simulating the airborne fire control radar signal of the fighter jet in the maneuvering state, and test the performance of radar reconnaissance and jamming equipment.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] A method for simulating airborne fire control radar signals based on a UAV is implemented based on an airborne fire control radar simulation device installed on the UAV, and includes the following steps:

[0007] Step S1, setting the airborne fire control radar transmission signal, and establishing the radar transmission signal parameters according to the detection mode of the fighter aircraft-borne fire control radar;

[0008] Step S2: setting a maneuvering scenario of the fighter to be simulated, and establishing a corresponding maneuvering scenario description according to the fighter's maneuvering mode, including but not limited to path, speed, and attitude information;

[0009] Step S3, calculating the attitude and speed characteristics of the fighter jet at a certain moment according to the maneuvering scenario set in step S2;

[0010] Step S4: Calculate the deviation of multiple parameters of the simulated airborne fire control radar of the UAV in the maneuvering scenario based on the attitude and speed characteristics obtained in step S3. The multiple parameters include but are not limited to signal power, carrier frequency, pulse repetition frequency, and pulse width;

[0011] Step S5: Based on the result of step S4 and the current UAV airborne radar transmission waveform, the deviation of the radar transmission signal parameters is adjusted and compensated by controlling the radar antenna array channel power and changing the transmission signal parameters, thereby achieving a realistic simulation of the airborne fire control radar radiation signal in a maneuvering scenario.

[0012] Furthermore, in the above-mentioned step S1, the radar transmission signal parameters include but are not limited to power, carrier frequency, pulse repetition frequency, and pulse width parameters.

[0013] Furthermore, in the above step S2, the fighter's maneuvering modes include but are not limited to maximum acceleration and deceleration flight, maximum overload climb / dive flight, maneuvering turn / somersault flight, and stable level flight; the above maneuvering modes are described by the following parameters:

[0014] (1) Maximum acceleration: acceleration for level flight a1, acceleration for level flight a2, acceleration for overload climb a3, acceleration for overload dive a4, acceleration for horizontal turn a5, acceleration for vertical loop a6;

[0015] (2) Level flight speed v1;

[0016] (3) Overload climb angle θ1 and overload dive angle θ2;

[0017] (4) The state of the maneuvering phase includes four parameters: time, speed, position, and angle.

[0018] Furthermore, the above step S3 specifically comprises the following steps:

[0019] Assume that P and v are the three-dimensional position and velocity of the carrier respectively, θ, are respectively the azimuth and pitch angles of the aircraft, r is the turning radius of the aircraft, P0, v0, θ0, are the initial position, speed, azimuth and pitch angle of the aircraft respectively, and Δt is the duration of the maneuver mode;

[0020] (1) Maximum acceleration and deceleration flight

[0021] The maneuver model for maximum acceleration and deceleration flight is as follows:

[0022]

[0023] (2) Maneuvering turns / somersaults

[0024] A turning / loop maneuver in which the trajectory of the aircraft is approximately circular in the maneuvering plane. If the maneuvering plane is horizontal, it is a turn; if the maneuvering plane is vertical, it is a loop.

[0025] Let P x is the position of the carrier aircraft in the horizontal plane along the fuselage direction, P y is the position of the carrier aircraft in the horizontal plane along the vertical direction of the fuselage, P z is the vertical position of the carrier aircraft, P x0 、P y0 、P z0 are the corresponding initial positions, v x 、v y 、v z are the maneuvering speeds in the corresponding directions respectively;

[0026] When flying in a turn, the maneuver model is as follows:

[0027]

[0028] When flying in a loop, its maneuver model is as follows:

[0029]

[0030] (3) Overload climb / dive flight

[0031] The overload climb / dive maneuver consists of three stages: a uniform circular turn, a climb / dive at a certain inclination angle, and a stable level flight. The climb and dive maneuvers are inverse processes of each other.

[0032] During climbing flight, the first stage maneuver is described by formula (2) or (3), and the third stage maneuver is described by formula (1). Let P z is the vertical position of the carrier aircraft, P z0 is the initial position in the vertical direction, v z0 is the initial velocity in the vertical direction, and the second stage maneuver model is as follows:

[0033]

[0034] Furthermore, in the above step S4, the change in the carrier aircraft attitude causes the radar radiation power deviation, and the steps are: assuming that the antenna pattern of the airborne fire control radar at a certain moment in the scanning process is θ、 are the azimuth and elevation angles of the antenna pattern, respectively. In the maneuvering state, the radar antenna gain relative to the direction of the radar reconnaissance jamming equipment is obtained as follows:

[0035] First, calculate the angle change caused by the change of the carrier's attitude. Assume that the longitude, latitude, and altitude coordinates of the carrier during maneuvering are (Lon, Lat, H), and its coordinates (X, Y, Z) in the geocentric coordinate system satisfy

[0036]

[0037] Where N is the ellipsoidal Earth and e is the eccentricity;

[0038] Then, convert the above geocentric coordinates into the northeast sky geographic coordinate system. Assuming that the northeast sky geographic coordinates are (Ea, No, Sp) and the geocentric coordinate system of the radar reconnaissance jamming equipment is (X0, Y0, Z0), then

[0039]

[0040] Finally, the above-mentioned northeastern sky geographic coordinate system is converted into the carrier rectangular coordinate system. Assuming that the coordinates of the carrier rectangular coordinate system are (x, y, z), and the yaw angle, pitch angle, and roll angle of the carrier are (α, β, γ), then

[0041]

[0042] During the time Δt, the coordinate change of the radar reconnaissance jammer position along the (x, y, z) direction is (Δx, Δy, Δz). At this time, the azimuth and elevation angles of the radar reconnaissance jammer relative to the carrier aircraft are:

[0043]

[0044] That is, in the radar carrier maneuvering scenario, the radar antenna gain in the direction of the radar reconnaissance jamming equipment is the antenna gain value corresponding to the azimuth and elevation angles after coordinate transformation.

[0045] Furthermore, in the above step S4, the deviation of the radar signal characteristics caused by the difference in the speed of the carrier aircraft includes:

[0046] (2.1) Carrier frequency deviation

[0047] During the maneuvering process, the carrier aircraft moves relative to the radar reconnaissance jammer, causing a deviation between the carrier frequency of the received signal and the carrier frequency of the actual radiated signal. This deviation is the Doppler frequency, and its change is proportional to the relative speed between the two.

[0048]

[0049] Where V is the relative speed between the radar and the radar reconnaissance jammer; C is the speed of light; f0 is the frequency of the radar's transmitted signal;

[0050] (2.2) Pulse repetition frequency deviation

[0051] Radar reconnaissance jamming equipment detects pulse repetition frequency by measuring the time interval between two pulses. Assuming that the distance between the airborne fire control radar and the radar reconnaissance jamming equipment is R, the speed of the radar carrier relative to the radar reconnaissance jamming equipment is V, the pulse repetition frequency of the radar transmitted pulse signal is prf, and the radar transmitted pulse coherence interval is PRI, then:

[0052] (2.21) Arrival time of the first pulse:

[0053] (2.22) Arrival time of the second pulse:

[0054] (2.23) The actual interval between the two received pulses is:

[0055] The relationship for conversion to pulse repetition frequency is as follows:

[0056]

[0057] Where prf' is the actual pulse repetition frequency measurement value, and the pulse repetition frequency deviation is:

[0058]

[0059] (2.3) Pulse width deviation

[0060] Radar reconnaissance jamming equipment detects radar pulse width by measuring the interval between the arrival times of the leading and trailing edges of the pulse. Assuming that the radar pulse width is τ, then:

[0061] (2.31), Pulse front arrival time:

[0062] (2.32) Pulse delayed arrival time:

[0063] (2.33) The interval between the leading and trailing edges of the pulse is:

[0064] That is, the actual pulse width measurement value is:

[0065] Then the pulse width deviation is:

[0066]

[0067] Furthermore, the above step S5 specifically comprises the following steps:

[0068] Taking a certain moment as the benchmark, the speed and position (x0, y0, z0) at that moment are selected as initialization parameters, the carrier attitude and speed changes corresponding to different time points are calculated, and different antenna gain, frequency, repetition rate, and pulse width parameters are set;

[0069] (1) Antenna gain change

[0070] S5.11. Calculate the corresponding aircraft attitude and position changes (x0 + Δx0, y0 + Δy0, z0 + Δz0) at regular time intervals according to formulas (1) to (4).

[0071] S5.12. To obtain the azimuth and pitch angles of the radar reconnaissance jammer relative to the flight direction of the simulated fighter, use formulas (6) to (8) to convert the longitude, latitude, and altitude coordinates (Lon, Lat, H) of the radar reconnaissance jammer to the rectangular coordinate system (x, y, z) relative to the aircraft body.

[0072] S5.13 At this point, the pitch and azimuth angles of the radar reconnaissance jammer relative to the simulated fighter are:

[0073]

[0074] Finally, the corresponding antenna gain is obtained according to the elevation angle and azimuth angle

[0075] S5.14. Use the power control function of the radar transceiver subsystem to reduce or increase the transmit power accordingly to simulate the change in radar antenna gain during fighter maneuvering scenarios;

[0076] (2) Carrier frequency changes

[0077] S5.21. Using formulas (1) to (4), obtain the speed difference ΔV between the UAV and the fighter relative to the radar reconnaissance jamming equipment.

[0078] S5.22. Calculate the radar signal carrier frequency deviation after the UAV replaces the fighter jet using formula (9).

[0079]

[0080] S5.23, when the UAV-mounted radar transmits a signal, the signal carrier frequency deviation f d , adjust the corresponding carrier frequency to simulate the carrier frequency change of fighter-borne fire control radar in a maneuvering scenario;

[0081] (3) Pulse repetition frequency deviation compensation

[0082] S5.31. From formulas (1) to (4), obtain the speed difference ΔV between the UAV and the fighter relative to the radar reconnaissance jamming equipment.

[0083] S5.32. Calculate the pulse repetition frequency deviation value after the UAV replaces the fighter jet using formula (11).

[0084]

[0085] S5.33. When the UAV-mounted radar transmits a signal, adjust the corresponding pulse repetition frequency according to the pulse repetition frequency deviation value Δprf to simulate the pulse repetition frequency change of the fighter-mounted fire control radar in a maneuvering scenario;

[0086] (4) Pulse width deviation compensation

[0087] S5.41. From formulas (1) to (4), obtain the speed difference ΔV between the UAV and the fighter relative to the radar reconnaissance jamming equipment.

[0088] S5.42. Calculate the pulse width measurement deviation after the UAV replaces the fighter jet using formula (12).

[0089]

[0090] S5.43. When the UAV airborne radar transmits a signal, the corresponding transmit pulse width is adjusted according to the pulse width deviation Δτ to simulate the pulse width change of the fighter-borne fire control radar in a maneuvering scenario.

[0091] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0092] This UAV-based airborne fire control radar signal simulation method uses UAVs instead of fighter jets as the flight platform for airborne fire control radars. When the UAV's maneuverability is weaker than that of the fighter jet, the radar transmit power control is used to simulate the radar power changes in the fighter jet's maneuvering state, which is conducive to giving full play to the relatively flexible and convenient advantages of UAV use and greatly reduces the simulation cost. A quantitative relationship and compensation method are established between the speed difference between the UAV and the fighter jet and the change in the detection and reception radar signal, which improves the realism of the simulated typical airborne fire control radar signal, is conducive to improving the credibility of the performance test of radar reconnaissance and jamming equipment, etc., and has good promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Figure 1 It is a flow chart of the airborne fire control radar signal simulation method based on UAV of the present invention;

[0094] Figure 2 This is a schematic diagram of the change in carrier frequency offset caused by speed difference;

[0095] Figure 3 This is a schematic diagram of the change in pulse repetition frequency offset caused by speed difference;

[0096] Figure 4 This is a schematic diagram of the pulse width offset change caused by speed difference. DETAILED DESCRIPTION

[0097] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0098] like Figure 1 As shown, a method for simulating airborne fire control radar signals based on a UAV is implemented based on an airborne fire control radar simulation device installed on the UAV, and includes the following steps:

[0099] Step S1: Setting the airborne fire control radar transmission signal, and establishing the radar transmission signal parameters according to the detection mode of the fighter aircraft fire control radar; the above parameters are set directly through the radar display and control interface, or by loading a parameter file;

[0100] Step S2: Setting the maneuvering scenario of the fighter to be simulated, and establishing a corresponding maneuvering scenario description according to the fighter's maneuvering mode, including but not limited to path, speed, and attitude information; setting is performed directly through the radar display and control interface, or by loading a parameter file;

[0101] Fighter jets have higher maneuverability than drones. Fighter jet maneuvers include but are not limited to maximum acceleration and deceleration flight, maximum overload climb / dive flight, maneuverable turns / loops, and stable level flight. These maneuvers are described by the following parameters:

[0102] (1) Maximum acceleration: acceleration for level flight a1, acceleration for level flight a2, acceleration for overload climb a3, acceleration for overload dive a4, acceleration for horizontal turn a5, acceleration for vertical loop a6;

[0103] (2) Level flight speed v1;

[0104] (3) Overload climb angle θ1 and overload dive angle θ2;

[0105] (4) The state of the maneuvering phase includes four parameters: time, speed, position, and angle.

[0106] Step S3, calculating the attitude and speed characteristics of the fighter jet at a certain moment according to the maneuvering scenario set in step S2;

[0107] The attitude (angle) and velocity at a certain moment are calculated by the maneuvering scene model. Let P and v be the three-dimensional position and velocity of the carrier respectively, θ, are respectively the azimuth and pitch angles of the aircraft, r is the turning radius of the aircraft, P0, v0, θ0, are the initial position, speed, azimuth and pitch angle of the aircraft respectively, and Δt is the duration of the maneuver mode;

[0108] (1) Maximum acceleration and deceleration flight

[0109] Maximum acceleration and deceleration flight, that is, a maneuver that changes the speed without changing the direction of the speed; in particular, when the acceleration is 0, it is stable level flight; its maneuver model is as follows:

[0110]

[0111] (2) Maneuvering turns / somersaults

[0112] A turning / loop maneuver in which the trajectory of the aircraft is approximately circular in the maneuvering plane. If the maneuvering plane is horizontal, it is a turn; if the maneuvering plane is vertical, it is a loop.

[0113] Let P x is the position of the carrier aircraft in the horizontal plane along the fuselage direction, P y is the position of the carrier aircraft in the horizontal plane along the vertical direction of the fuselage, P z is the vertical position of the carrier aircraft, P x0 、P y0 、P z0 are the corresponding initial positions, v x 、v y 、v z are the maneuvering speeds in the corresponding directions respectively;

[0114] When flying in a turn, the maneuver model is as follows:

[0115]

[0116] When flying in a loop, its maneuver model is as follows:

[0117]

[0118] (3) Overload climb / dive flight

[0119] The overload climb / dive maneuver consists of three stages: a uniform circular turn, a climb / dive at a certain inclination angle, and a stable level flight. The climb and dive maneuvers are inverse processes of each other.

[0120] Taking climbing flight as an example, the first stage maneuver is described by formula (2) or (3), and the third stage maneuver is described by formula (1). Let P z is the vertical position of the carrier aircraft, P z0 is the initial position in the vertical direction, v z0 is the initial velocity in the vertical direction, and the second stage maneuver model is as follows:

[0121]

[0122] Step S4: Calculate the deviation of multiple parameters of the simulated airborne fire control radar of the UAV in the maneuvering scenario based on the attitude and speed characteristics obtained in step S3. The multiple parameters include but are not limited to signal power, carrier frequency, pulse repetition frequency, and pulse width;

[0123] During the maneuvering process, the radar carrier aircraft's attitude and speed will change. This will cause the spatial relationship between the actual radar beam and the radar reconnaissance jamming equipment to change. On the other hand, it will also cause the radar signal frequency, repetition rate, pulse width, etc. received by the radar reconnaissance jamming equipment to change.

[0124] (1) Radar radiation power deviation caused by aircraft attitude change

[0125] When there are differences in the carrier aircraft's attitude, the radar radiation signal power actually received by the radar reconnaissance jamming equipment will change with the change in the actual direction of the radar pattern during the maneuver. The radar pattern is described by a mathematical model or loaded with measured data, which is a known condition. Assume that the antenna pattern of the airborne fire control radar at a certain moment in the scanning process is θ、 are the azimuth and elevation angles of the antenna pattern, respectively. In the maneuvering state, the radar antenna gain relative to the direction of the radar reconnaissance jamming equipment is obtained as follows:

[0126] First, calculate the angle change caused by the change of the carrier's attitude. Assume that the longitude, latitude, and altitude coordinates of the carrier during maneuvering are (Lon, Lat, H), and its coordinates (X, Y, Z) in the geocentric coordinate system satisfy

[0127]

[0128] Where N is the ellipsoidal Earth and e is the eccentricity;

[0129] Next, convert the above geocentric coordinates into the Northeast Sky geographic coordinate system. Assuming that the Northeast Sky geographic coordinates are (Ea, No, Sp) and the geocentric coordinate system of the radar reconnaissance jammer is (X0, Y0, Z0), then

[0130]

[0131] Finally, the above-mentioned northeastern sky geographic coordinate system is converted into the carrier rectangular coordinate system. Assuming that the coordinates of the carrier rectangular coordinate system are (x, y, z), and the yaw angle, pitch angle, and roll angle of the carrier are (α, β, γ), then

[0132]

[0133] During the time Δt, the coordinate change of the radar reconnaissance jammer position along the (x, y, z) direction is (Δx, Δy, Δz). At this time, the azimuth and elevation angles of the radar reconnaissance jammer relative to the carrier aircraft are:

[0134]

[0135] That is, in the radar carrier maneuvering scenario, the radar antenna gain in the direction of the radar reconnaissance jamming equipment is the antenna gain value corresponding to the azimuth and elevation angles after coordinate transformation;

[0136] (2) Deviations in radar signal characteristics caused by differences in carrier aircraft speed

[0137] Due to the different flight capabilities of different carrier aircraft, when the radar sends the same signal, the signal actually received by the radar reconnaissance jammer will be different, mainly manifested in the deviation of the radar signal carrier frequency, pulse repetition frequency and pulse width;

[0138] (2.1) Carrier frequency deviation

[0139] During the maneuvering process, the carrier aircraft moves relative to the radar reconnaissance jammer, causing a deviation between the carrier frequency of the received signal and the carrier frequency of the actual radiated signal. This deviation is the Doppler frequency, and its change is proportional to the relative speed between the two.

[0140]

[0141] Where V is the relative speed between the radar and the radar reconnaissance jammer; C is the speed of light; f0 is the frequency of the radar's transmitted signal;

[0142] (2.2) Pulse repetition frequency deviation

[0143] Radar reconnaissance jamming equipment detects pulse repetition frequency by measuring the time interval between two pulses. Assuming that the distance between the airborne fire control radar and the radar reconnaissance jamming equipment is R, the speed of the radar carrier relative to the radar reconnaissance jamming equipment is V, the pulse repetition frequency of the radar transmitted pulse signal is prf, and the radar transmitted pulse coherence interval is PRI, then:

[0144] (2.21) Arrival time of the first pulse:

[0145] (2.22) Arrival time of the second pulse:

[0146] (2.23) The actual interval between the two received pulses is:

[0147] The relationship for conversion to pulse repetition frequency is as follows:

[0148]

[0149] Where prf' is the actual pulse repetition frequency measurement value, and the pulse repetition frequency deviation is:

[0150]

[0151] (2.3) Pulse width deviation

[0152] Radar reconnaissance jamming equipment detects radar pulse width by measuring the interval between the arrival times of the leading and trailing edges of the pulse. Assuming that the radar pulse width is τ, then:

[0153] (2.31), Pulse front arrival time:

[0154] (2.32) Pulse delayed arrival time:

[0155] (2.33) The interval between the leading and trailing edges of the pulse is:

[0156] That is, the actual pulse width measurement value is:

[0157] Then the pulse width deviation is:

[0158]

[0159] Step S5: Based on the result of step S4 and the current UAV airborne radar transmit waveform, the deviation of the radar transmit signal parameters is adjusted and compensated by controlling the radar antenna array channel power and changing the transmit signal parameters, thereby achieving a realistic simulation of the airborne fire control radar radiation signal in a maneuvering scenario. The specific steps are as follows:

[0160] Taking a certain moment as the benchmark, the speed and position (x0, y0, z0) at that moment are selected as initialization parameters, the carrier attitude and speed changes corresponding to different time points are calculated, and different antenna gain, frequency, repetition rate, and pulse width parameters are set;

[0161] (1) Antenna gain change

[0162] S5.11. Calculate the corresponding aircraft attitude (i.e., velocity direction) and position change (x0 + Δx0, y0 + Δy0, z0 + Δz0) at a certain time interval according to formulas (1) to (4).

[0163] S5.12. To obtain the azimuth and pitch angles of the radar reconnaissance jammer relative to the flight direction of the simulated fighter, use formulas (6) to (8) to convert the longitude, latitude, and altitude coordinates (Lon, Lat, H) of the radar reconnaissance jammer to the rectangular coordinate system (x, y, z) relative to the aircraft body.

[0164] S5.13 At this point, the pitch and azimuth angles of the radar reconnaissance jammer relative to the simulated fighter are:

[0165]

[0166] Finally, the corresponding antenna gain is obtained according to the elevation angle and azimuth angle

[0167] S5.14. Use the power control function of the radar transceiver subsystem to reduce or increase the transmit power accordingly to simulate the change in radar antenna gain during fighter maneuvering scenarios;

[0168] (2) Carrier frequency changes

[0169] S5.21. Using formulas (1) to (4), obtain the speed difference ΔV between the UAV and the fighter relative to the radar reconnaissance jamming equipment.

[0170] S5.22. Calculate the radar signal carrier frequency deviation after the UAV replaces the fighter jet using formula (9).

[0171]

[0172] S5.23, when the UAV-mounted radar transmits a signal, the signal carrier frequency deviation f d, adjust the corresponding carrier frequency to simulate the carrier frequency changes of the fighter-borne fire control radar in a maneuvering scenario.

[0173] Taking radar carrier frequencies of 8 GHz, 10 GHz, 12 GHz, 15 GHz, and 17 GHz as examples, the distribution of carrier frequency deviations caused by differences in radar carrier speeds can be found in Figure 2 .Depend on Figure 2 It is known that the carrier frequency deviation value that needs to be compensated is determined by the carrier speed difference and the actual carrier frequency. When the radar carrier speed difference is larger and the actual carrier frequency is higher, the carrier frequency deviation value that needs to be compensated is larger.

[0174] (3) Pulse repetition frequency deviation compensation

[0175] S5.31. From formulas (1) to (4), obtain the speed difference ΔV between the UAV and the fighter relative to the radar reconnaissance jamming equipment.

[0176] S5.32. Calculate the pulse repetition frequency deviation value after the UAV replaces the fighter jet using formula (11).

[0177]

[0178] S5.33. When the UAV-mounted radar transmits a signal, adjust the corresponding pulse repetition frequency according to the pulse repetition frequency deviation value Δprf to simulate the pulse repetition frequency change of the fighter-mounted fire control radar in a maneuvering scenario;

[0179] Taking the relative speed differences of 200m / s, 300m / s, 400m / s, and 500m / s as examples, the distribution of the signal pulse repetition frequency deviation values ​​is shown in Figure 2. Figure 3 .Depend on Figure 3 It is known that the pulse repetition frequency value that needs to be compensated is determined by the carrier speed difference and the actual pulse repetition frequency. When the radar carrier speed difference is larger and the actual pulse repetition frequency is higher, the pulse repetition frequency deviation value that needs to be compensated is larger.

[0180] (4) Pulse width deviation compensation

[0181] S5.41. From formulas (1) to (4), obtain the speed difference ΔV between the UAV and the fighter relative to the radar reconnaissance jamming equipment.

[0182] S5.42. Calculate the pulse width measurement deviation after the UAV replaces the fighter jet using formula (12).

[0183]

[0184] S5.43. When the UAV airborne radar transmits a signal, the corresponding transmit pulse width is adjusted according to the pulse width deviation Δτ to simulate the pulse width change of the fighter-borne fire control radar in a maneuvering scenario.

[0185] For example, the relative speed differences of 200m / s, 300m / s, 400m / s, and 500m / s respectively will cause the distribution of pulse width deviation values. Figure 4 .Depend on Figure 4 It is known that the pulse width deviation value that needs to be compensated is determined by the carrier speed difference and the actual pulse width. When the radar carrier speed difference is larger and the actual pulse width is wider, the pulse width deviation value that needs to be compensated is larger.

[0186] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, all equivalent changes and modifications made within the scope of the patent application of the present invention shall fall within the scope of patent protection of the present invention.

Claims

1. A method for simulating airborne fire control radar signals based on a UAV, characterized by: It is implemented based on an airborne fire control radar simulator installed on a UAV and includes the following steps: Step S1, setting the airborne fire control radar transmission signal, and establishing the radar transmission signal parameters according to the detection mode of the fighter aircraft-borne fire control radar; Step S2: setting a maneuvering scenario of the fighter to be simulated, and establishing a corresponding maneuvering scenario description according to the fighter's maneuvering mode, including path, speed, and attitude information; Step S3, calculating the attitude and speed characteristics of the fighter jet at a certain moment according to the maneuvering scenario set in step S2; Step S4: Calculate the deviation of multiple parameters of the simulated airborne fire control radar of the UAV in the maneuvering scenario based on the attitude and speed characteristics obtained in step S3, wherein the multiple parameters include signal power, carrier frequency, pulse repetition frequency, and pulse width; Step S5: Based on the result of step S4 and the current UAV airborne radar transmission waveform, the deviation of the radar transmission signal parameters is adjusted and compensated by controlling the radar antenna array channel power and changing the transmission signal parameters, thereby achieving a realistic simulation of the airborne fire control radar radiation signal in a maneuvering scenario.

2. The method for simulating airborne fire control radar signals based on a UAV according to claim 1, wherein: In step S1, the radar transmission signal parameters include power, carrier frequency, pulse repetition frequency, and pulse width parameters.

3. The method for simulating airborne fire control radar signals based on a UAV according to claim 1, wherein: In step S2, the fighter's maneuvering modes include maximum acceleration and deceleration flight, maximum overload climb / dive flight, maneuvering turn / somersault flight, and stable level flight; the above maneuvering modes are described by the following parameters: (1) Maximum acceleration: acceleration for level flight a1, acceleration for level flight a2, acceleration for overload climb a3, acceleration for overload dive a4, acceleration for horizontal turn a5, acceleration for vertical loop a6; (2) Level flight speed v1; (3) Overload climb angle θ1 and overload dive angle θ2; (4) The state of the maneuvering phase includes four parameters: time, speed, position, and angle.

4. The method for simulating airborne fire control radar signals based on a UAV according to claim 3, wherein step S3 comprises the following steps: Let p and v be the three-dimensional position and velocity of the carrier respectively, θ, are respectively the azimuth and pitch angles of the aircraft, r is the turning radius of the aircraft, p0, v0, θ0, are the initial position, speed, azimuth and pitch angle of the aircraft respectively, and Δt is the duration of the maneuver mode; (1) Maximum acceleration and deceleration flight The maneuver model for maximum acceleration and deceleration flight is as follows: (2) Maneuvering turns / somersaults A turning / loop maneuver in which the trajectory of the aircraft is approximately circular in the maneuvering plane. If the maneuvering plane is horizontal, it is a turn; if the maneuvering plane is vertical, it is a loop. Let P x is the position of the carrier aircraft in the horizontal plane along the fuselage direction, P y is the position of the carrier aircraft in the horizontal plane along the vertical direction of the fuselage, P z is the vertical position of the carrier aircraft, P x0 、P y0 、P z0 are the corresponding initial positions, v x 、v y 、v z are the maneuvering speeds in the corresponding directions respectively; When flying in a turn, the maneuver model is as follows: When flying in a loop, its maneuver model is as follows: (3) Overload climb / dive flight The overload climb / dive maneuver consists of three stages: a uniform circular turn, a climb / dive at a certain inclination angle, and a stable level flight. The climb and dive maneuvers are inverse processes of each other. During climbing flight, the first stage maneuver is described by formula (2) or (3), and the third stage maneuver is described by formula (1). Let P z is the vertical position of the carrier aircraft, P z0 is the initial position in the vertical direction, v z0 is the initial velocity in the vertical direction, and the second stage maneuver model is as follows:

5. The method for simulating airborne fire control radar signals based on a UAV according to claim 4, wherein: In step S4, the change of the carrier aircraft attitude causes the deviation of the radar radiation power. The steps are as follows: suppose the antenna pattern of the airborne fire control radar at a certain moment in the scanning process is θ、 are the azimuth and elevation angles of the antenna pattern, respectively. In the maneuvering state, the radar antenna gain relative to the direction of the radar reconnaissance jamming equipment is obtained as follows: First, calculate the angle change caused by the change of the carrier's attitude. Assume that the longitude, latitude, and altitude coordinates of the carrier during maneuvering are (Lon, Lat, H), and its coordinates (X, Y, Z) in the geocentric coordinate system satisfy Where N is the ellipsoidal Earth and e is the eccentricity; Then, convert the above geocentric coordinates into the northeast sky geographic coordinate system. Assuming that the northeast sky geographic coordinates are (Ea, No, Sp) and the geocentric coordinate system of the radar reconnaissance jamming equipment is (X0, Y0, Z0), then Finally, the above-mentioned northeastern sky geographic coordinate system is converted into the carrier rectangular coordinate system. Assuming that the coordinates of the carrier rectangular coordinate system are (x, y, z), and the yaw angle, pitch angle, and roll angle of the carrier are (α, β, γ), then During the time Δt, the coordinate change of the radar reconnaissance jammer position along the (x, y, z) direction is (Δx, Δy, Δz). At this time, the azimuth and elevation angles of the radar reconnaissance jammer relative to the carrier aircraft are: That is, in the radar carrier maneuvering scenario, the radar antenna gain in the direction of the radar reconnaissance jamming equipment is the antenna gain value corresponding to the azimuth and elevation angles after coordinate transformation.

6. The method for simulating airborne fire control radar signals based on a UAV according to claim 5, wherein: In step S4, Differences in aircraft speeds cause deviations in radar signal characteristics, including: (2.1) Carrier frequency deviation During the maneuvering process, the carrier aircraft moves relative to the radar reconnaissance jammer, causing a deviation between the carrier frequency of the received signal and the carrier frequency of the actual radiated signal. This deviation is the Doppler frequency, and its change is proportional to the relative speed between the two. Where V is the relative speed between the radar and the radar reconnaissance jammer; C is the speed of light; f0 is the frequency of the radar's transmitted signal; (2.2) Pulse repetition frequency deviation Radar reconnaissance jamming equipment detects pulse repetition frequency by measuring the time interval between two pulses. Assuming that the distance between the airborne fire control radar and the radar reconnaissance jamming equipment is R, the speed of the radar carrier relative to the radar reconnaissance jamming equipment is V, the pulse repetition frequency of the radar transmitted pulse signal is prf, and the radar transmitted pulse coherence interval is PRI, then: (2.21) Arrival time of the first pulse: (2.22) Arrival time of the second pulse: (2.23) The actual interval between the two received pulses is: The relationship for conversion to pulse repetition frequency is as follows: Where prf' is the actual pulse repetition frequency measurement value, and the pulse repetition frequency deviation is: (2.3) Pulse width deviation Radar reconnaissance jamming equipment detects radar pulse width by measuring the interval between the arrival times of the leading and trailing edges of the pulse. Assuming that the radar pulse width is τ, then: (2.31), Pulse front arrival time: (2.32) Pulse delayed arrival time: (2.33) The interval between the leading and trailing edges of the pulse is: That is, the actual pulse width measurement value is: Then the pulse width deviation is:

7. The method for simulating airborne fire control radar signals based on a UAV according to claim 6, wherein step S5 comprises the following steps: Taking a certain moment as the benchmark, the speed and position (x0, y0, z0) at that moment are selected as initialization parameters, the carrier attitude and speed changes corresponding to different time points are calculated, and different antenna gain, frequency, repetition rate, and pulse width parameters are set; among them, The antenna gain changes in the following steps: S5.

11. Calculate the corresponding aircraft attitude and position changes (x0 + Δx0, y0 + Δy0, z0 + Δz0) at regular time intervals according to formulas (1) to (4), where Δx0, Δy0, and Δz0 are the coordinate changes along the (x, y, z) directions. S5.

12. To obtain the azimuth and pitch angles of the radar reconnaissance jammer relative to the flight direction of the simulated fighter, use formulas (6) to (8) to convert the longitude, latitude, and altitude coordinates (Lon, Lat, H) of the radar reconnaissance jammer to the rectangular coordinate system (x, y, z) relative to the aircraft body. S5.13 At this point, the pitch and azimuth angles of the radar reconnaissance jammer relative to the simulated fighter are: Finally, the corresponding antenna gain is obtained according to the elevation angle and azimuth angle S5.

14. Use the power control function of the radar transceiver subsystem to reduce or increase the transmit power accordingly to simulate the change in radar antenna gain in a fighter jet maneuvering scenario.

8. The method for simulating airborne fire control radar signals based on a UAV according to claim 6, wherein the carrier frequency is changed by the following steps: S5.

21. Using formulas (1) to (4), obtain the speed difference ΔV between the UAV and the fighter relative to the radar reconnaissance jamming equipment. S5.

22. Calculate the radar signal carrier frequency deviation after the UAV replaces the fighter jet using formula (9). S5.23, when the UAV-mounted radar transmits a signal, the signal carrier frequency deviation f d , adjust the corresponding carrier frequency to simulate the carrier frequency changes of the fighter-borne fire control radar in a maneuvering scenario.

9. The method for simulating airborne fire control radar signals based on a UAV according to claim 6, wherein: The pulse repetition frequency deviation compensation steps are as follows: S5.

31. From formulas (1) to (4), obtain the speed difference ΔV between the UAV and the fighter relative to the radar reconnaissance jamming equipment. S5.

32. Calculate the pulse repetition frequency deviation value after the UAV replaces the fighter jet using formula (11). S5.

33. When the UAV-borne radar transmits a signal, it adjusts the corresponding pulse repetition frequency according to the pulse repetition frequency deviation value Δprf to simulate the pulse repetition frequency change of the fighter-borne fire control radar in a maneuvering scenario.

10. The method for simulating airborne fire control radar signals based on a UAV according to claim 6, wherein: The pulse width deviation compensation steps are as follows: S5.

41. From formulas (1) to (4), obtain the speed difference ΔV between the UAV and the fighter relative to the radar reconnaissance jamming equipment. S5.

42. Calculate the pulse width measurement deviation after the UAV replaces the fighter jet using formula (12). S5.

43. When the UAV airborne radar transmits a signal, the corresponding transmit pulse width is adjusted according to the pulse width deviation Δτ to simulate the pulse width change of the fighter-borne fire control radar in a maneuvering scenario.

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