Forward airborne collision avoidance system based on conformal phased array antenna and its working method

Abstract

The present invention provides a forward airborne collision avoidance system based on a conformal phased array antenna and its working method. In this system, the conformal phased array antenna serves as the receiving device for response signals; the collision avoidance host is used to complete interrogation coding, response decoding, monopulse angle measurement, target monitoring, and collision avoidance warning processing, and report the obtained target point track and collision avoidance warning information to the display and control device for display; among them, the monopulse angle measurement refers to monopulse angle measurement based on forming sum and difference beams by the phased array. The present invention uses a conformal phased array antenna as the receiving device for response signals. The antenna is conformal with the aircraft wing and does not affect the aerodynamic characteristics of the aircraft, and is applicable to aircraft with higher speeds and smaller volumes; at the same time, the method of monopulse angle measurement by forming sum and difference beams using a digital phased array can greatly improve the angle measurement accuracy of the system for targets compared with the traditional two-channel amplitude comparison / phase comparison angle measurement method.

Description

Technical Field

[0001] The present invention relates to the technical field of airborne collision avoidance systems, and in particular, to a forward airborne collision avoidance system based on a conformal phased array antenna and its working method. Background Art

[0002] The airborne collision avoidance system is developed based on SSR, and its working modes are only C mode and MS. It also adopts the inquiry / response working method, and can detect the azimuth, altitude, and speed information of the aircraft. It is widely installed on medium and large aircraft to avoid mid-air collisions between aircraft.

[0003] The existing airborne collision avoidance system: uses a cross-shaped directional antenna as the response signal receiving device, which is independently installed on the top and abdomen of the aircraft body, resulting in poor aerodynamic characteristics of the aircraft. Especially for aircraft with higher speeds and smaller sizes, it affects the flight stability and maneuverability of the aircraft. Moreover, the airborne collision avoidance system using a cross-shaped directional antenna measures the angle by the dual-channel amplitude comparison / phase comparison method, and the angle measurement performance is greatly affected by interference signals. Summary of the Invention

[0004] The present invention aims to provide a forward airborne collision avoidance system based on a conformal phased array antenna and its working method to solve the problems existing in the existing airborne collision avoidance system using a cross-shaped directional antenna.

[0005] A forward airborne collision avoidance system based on a conformal phased array antenna provided by the present invention includes a collision avoidance host, a conformal phased array antenna connected to the collision avoidance host, and a display and control device;

[0006] The conformal phased array antenna serves as the response signal receiving device; the conformal phased array antenna includes a left-wing antenna and a right-wing antenna; the left-wing antenna and the right-wing antenna are used to form the required beams by means of digital phased array beamforming; among them, the superposition of all beams can cover 180° forward;

[0007] The collision avoidance host includes a PPC controller and an FPGA controller, which are used to complete inquiry encoding, response decoding, monopulse angle measurement, target monitoring, and collision avoidance warning processing under the control of the display and control device, and report the obtained target point track and collision avoidance warning information to the display and control device; among them, the monopulse angle measurement refers to the monopulse angle measurement based on the formation of sum and difference beams by the phased array.

[0008] The display and control device is used to send control commands to the collision avoidance host and display the target point track and collision avoidance warning information reported by the collision avoidance host.

[0009] Furthermore, the beams of the left-wing antenna and the right-wing antenna respectively cover the left 90° and the right 90° forward.

[0010] Further, both the left-wing antenna and the right-wing antenna include N omnidirectional antenna elements.

[0011] Further, the display and control device includes a human-machine interaction interface.

[0012] The working method of the above-mentioned forward airborne collision avoidance system based on conformal phased array antenna includes:

[0013] (1) Interrogation beam scheduling: The collision avoidance host is controlled by the display and control device to start working, and the PPC controller performs interrogation beam scheduling periodically.

[0014] (2) Interrogation coding: The FPGA controller performs coding for only C-mode and S-mode interrogations according to the commands issued by the PPC controller during interrogation beam scheduling.

[0015] (3) Digital beamforming: When interrogating or not interrogating, the conformal phased array antenna forms transmit beams, receive beams, or omnidirectional beams through digital beamforming, and outputs digital I / Q signals of sum / difference beams after conversion.

[0016] (4) Reply decoding: The FPGA controller receives the digital I / Q signals of the sum / difference beams, opens the corresponding reply decoding switch according to the interrogation mode, performs reply decoding according to the signal formats of C-mode and S-mode, extracts the C-code, S-mode data, amplitude / phase of the sum / difference beams of the target, calculates the target distance at the same time, and forms the original point track data to be reported to the PPC controller for processing.

[0017] (5) Monopulse angle measurement: The PPC controller uses the amplitude / phase of the sum / difference beams in the original point track data and calculates the target azimuth angle by using the relevant algorithms of monopulse angle measurement.

[0018] (6) Based on the real-time acquisition of the target distance, target azimuth angle, C-code, and S-mode data, the PPC controller completes the point track processing of the target, forms the track of the target and sends it to the display and control device for display; moreover, the PPC controller monitors the flight state of the target, combines the flight state of the aircraft itself, completes the judgment of the flight situation in the adjacent airspace, classifies the collision avoidance threat level of the target, and outputs the corresponding collision avoidance warning information according to the classification of the collision avoidance threat level to be reported to the display and control device for display.

[0019] Further, the process of the PPC controller performing interrogation beam scheduling periodically is as follows:

[0020] The 90° ranges covered by the left-wing antenna and the right-wing antenna are respectively evenly divided into m beams, obtaining a total of 2m beams; among them, the beam center pointing intervals of the 2m beams are 90° / m, and the beam width is designed as (90° / m)×1.5.

[0021] When only in C - mode interrogation, within each period, the PPC controller arranges a soft - call sequence and performs beam scheduling in sequence according to the order of beam 1 to beam 2m.

[0022] When in S - mode interrogation, within each period, the PPC controller determines the beam corresponding to the azimuth of each target to be interrogated according to the current S - mode target information list, and then arranges the beams in sequence as S - mode interrogation commands to conduct roll - call interrogation on S - mode targets.

[0023] Furthermore, the encoded output signals for performing only C - mode and S - mode interrogations include amplitude - modulation encoded signal ASK, phase - modulation encoded signal DPSK, power - amplifier switch encoded signal AM, transceiver - switching encoded signal TR, and decoder - gate encoded signal YM_GATE.

[0024] Furthermore, the specific process of digital beamforming includes:

[0025] When performing only C - mode or S - mode interrogation, the conformal phased - array antenna forms the required transmit beam and receive beam by means of digital beamforming according to the beam number of the current interrogation schedule; when TR = 1, the amplitude - modulation encoded signal ASK and the phase - modulation encoded signal DPSK are radiated through the transmit beam, and when TR = 0 and YM_GATE = 1, the response signal transmitted by the target is received through the receive beam, and the received response signal is converted to output the digital I / Q signals of the sum - and - difference channels.

[0026] When no interrogation is being performed, that is, when TR = 0 and YM_GATE = 0, an omnidirectional beam is formed by means of digital beamforming to detect the intermittent oscillation signal sent by S - mode targets in the air, and the detected intermittent oscillation signal is converted to output the digital I / Q signals of the sum - and - difference channels.

[0027] Furthermore, the method for calculating the target azimuth angle using the relevant algorithm of monopulse angle measurement is:

[0028] T m =T f +T Δ ;

[0029] Wherein, T m is the target azimuth angle, T f is the azimuth angle of the beam center of the conformal phased - array antenna relative to true north, and T Δ is the azimuth deviation of the target relative to the beam center of the conformal phased - array antenna within the main lobe of the beam.

[0030] In summary, due to the adoption of the above - mentioned technical solutions, the beneficial effects of the present invention are:

[0031] The present invention uses a conformal phased array antenna as the receiving device for the response signal. The antenna is conformal with the aircraft wing, thus not affecting the aerodynamic characteristics of the aircraft and being applicable to aircraft with higher speeds and smaller volumes. At the same time, the digital phased array is used to form sum / difference beams for monopulse angle measurement. Compared with the traditional angle measurement method of dual-channel amplitude comparison / phase comparison, it can greatly improve the angle measurement accuracy of the system for the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 Schematic diagram of the forward airborne collision avoidance system based on a conformal phased array antenna according to an embodiment of the present invention.

[0034] Figure 2 Main lobe (partial) and sum / difference direction diagrams of the antenna beam according to an embodiment of the present invention.

[0035] Figure 3 Schematic diagram of the relative positions of Target 1 and Target 2 and the beam center direction of the conformal phased array antenna according to an embodiment of the present invention.

[0036] Figure 4a Schematic diagram of the sum / difference beam phase difference of Target 1 according to an embodiment of the present invention.

[0037] Figure 4b Schematic diagram of the sum / difference beam phase difference of Target 2 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0040] Embodiment

[0041] As Figure 1 shown, this embodiment proposes a forward airborne collision avoidance system based on a conformal phased array antenna, which includes a collision avoidance host, a conformal phased array antenna connected to the collision avoidance host, and a display and control device;

[0042] The conformal phased array antenna serves as a receiving device for response signals; the conformal phased array antenna includes a left wing antenna and a right wing antenna; the left wing antenna and the right wing antenna each include N omnidirectional antenna elements, which are used to form required beams in the way of digital phased array beamforming; among them, the superposition of all beams can cover 180° forward; further, the beams of the left wing antenna and the right wing antenna respectively cover 90° on the left side and 90° on the right side of the forward direction.

[0043] The collision avoidance host includes a PPC controller and an FPGA controller, which are used to complete interrogation coding, response decoding, monopulse angle measurement, target monitoring, and collision avoidance warning processing under the control of the display and control device, and report the obtained target point track and collision avoidance warning information to the display and control device; among them, the monopulse angle measurement refers to the monopulse angle measurement based on the formation of sum / difference beams by the phased array.

[0044] The display and control device includes a human-machine interaction interface, which is used to send control commands to the collision avoidance host and display the target point track and collision avoidance warning information reported by the collision avoidance host.

[0045] Therefore, in the forward airborne collision avoidance system based on the conformal phased array antenna proposed in this embodiment, the conformal phased array antenna is used as a receiving device for response signals. The antenna is conformal with the aircraft wing and does not affect the aerodynamic characteristics of the aircraft, and is applicable to aircraft with higher speeds and smaller volumes; at the same time, the monopulse angle measurement method of forming sum / difference beams by digital phased array is adopted, which can greatly improve the angle measurement accuracy of the system for targets compared with the traditional two-channel amplitude comparison / phase comparison angle measurement method.

[0046] The working method of the above-mentioned forward airborne collision avoidance system based on a conformal phased array antenna is characterized by including:

[0047] (1) Interrogation beam scheduling: The display and control device controls the collision avoidance host to start working, and the PPC controller periodically performs interrogation beam scheduling.

[0048] The process of interrogation beam scheduling is as follows:

[0049] The 90° ranges covered by the left wing antenna and the right wing antenna are respectively evenly divided into m beams, obtaining a total of 2m beams; among them, the beam center pointing intervals of the 2m beams are 90° / m, and the beam width is designed as (90° / m)×1.5.

[0050] When only in C mode interrogation, within each period, the PPC controller arranges the whisper call commands and sequentially performs beam scheduling in the order of beam 1 to beam 2m; among them, the number of steps for interrogation within each beam is determined separately as needed.

[0051] When in S mode interrogation, within each period, the PPC controller determines the beam corresponding to the azimuth of each target to be interrogated according to the current S mode target information list, and then sequentially arranges the beams as S mode interrogation commands to conduct roll call interrogations on S mode targets;

[0052] (2) Interrogation encoding: The FPGA controller performs encoding for only C mode and S mode interrogations according to the whisper call commands and S mode interrogation commands issued by the PPC controller during interrogation beam scheduling; the encoding output signals include amplitude modulation encoding signal ASK, phase modulation encoding signal DPSK, power amplifier switch encoding signal AM, transceiver switching encoding signal TR, and decoding gate encoding signal YM_GATE.

[0053] (3) Digital beamforming: When conducting interrogation or not conducting interrogation, the conformal phased array antenna forms transmit beams, receive beams, or omnidirectional beams through digital beamforming, and outputs the digital I / Q signals of the sum / difference beams after conversion; the specific process is as follows:

[0054] When conducting only C mode or S mode interrogation, the conformal phased array antenna forms the required transmit beams and receive beams through digital beamforming according to the current interrogation-scheduled beam numbers (1 to 2m); when TR = 1, the amplitude modulation encoding signal ASK and the phase modulation encoding signal DPSK are radiated through the transmit beam, and when TR = 0 and YM_GATE = 1, the response signal transmitted by the target is received through the receive beam, and the received response signal is output as the digital I / Q signals of the sum / difference channels after conversion;

[0055] When not conducting interrogation, that is, when TR = 0 and YM_GATE = 0, an omnidirectional beam is formed through digital beamforming to detect the intermittent oscillation signals sent by S mode targets in the air, and the detected intermittent oscillation signals are output as the digital I / Q signals of the sum / difference channels after conversion.

[0056] (4) Response decoding: The FPGA controller receives the digital I / Q signals of the sum / difference beams, opens the corresponding response decoding switch according to the interrogation mode, performs response decoding according to the signal formats of C mode and S mode, extracts the C code of the target, S mode data, amplitude / phase of the sum / difference beams, and simultaneously calculates the target distance, and forms the original track data to report to the PPC controller for processing;

[0057] (5) Single-pulse angle measurement: The PPC controller calculates the target azimuth angle by using the amplitude / phase of the sum / difference beams in the original trace data and adopting the relevant algorithms of single-pulse angle measurement.

[0058] The method of calculating the target azimuth angle by adopting the relevant algorithms of single-pulse angle measurement is as follows:

[0059] T m = T f + T Δ ;

[0060] Among them, T m is the target azimuth angle, T f is the azimuth angle of the beam center pointing of the common phased array antenna (such as the zero elevation position shown in Figure 2 ) relative to true north, and T Δ is the azimuth deviation of the target relative to the beam center pointing of the common phased array antenna within the main lobe of the beam.

[0061] As shown in Figure 2 , within the main lobe of the beam, for large or small signals, the amplitude difference of the sum / difference beams |F Σ (θ)| - |F Δ (θ)| has the same fixed relationship with the azimuth deviation T Δ . The absolute value of the azimuth deviation |T Δ | of the target relative to the beam center pointing of the common phased array antenna within the main lobe of the beam can be obtained by comparing the amplitude difference of the sum / difference beams received by the target.

[0062] In order to analyze the judgment conditions for the target to be on the left / right of the beam center pointing of the common phased array antenna, as shown in Figure 3 , assume that two targets appear on the left and right of the beam center pointing of the common phased array antenna respectively:

[0063] Target 1 is on the left of the beam center pointing of the common phased array antenna. As shown in Figure 4a , the phase of the sum beam E1 Σ of the response signal lags behind the phase of the difference beam E1 Δ by 90°.

[0064] Target 2 is on the right of the beam center pointing of the common phased array antenna. As shown in Figure 4b , the phase of the sum beam E2 Σ of the response signal leads the phase of the difference beam E2 Δ by 90°.

[0065] The target azimuth angle can be obtained by comparing and calculating the amplitude and phase information of the sum / difference beams.

[0066] (6) Based on the real-time acquisition of the target distance, target azimuth, C code, and S-mode data, the PPC controller completes the point track processing of the target, forms the track of the target, and sends it to the display and control device for display. Moreover, by monitoring the flight state of the target and combining it with the flight state of the aircraft itself, the PPC controller completes the judgment of the flight situation in the adjacent airspace, classifies the collision avoidance threat level of the target, and outputs the corresponding collision avoidance warning information ((TA / RA)) according to the classification of the collision avoidance threat level and reports it to the display and control device for display.

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A forward airborne collision avoidance system based on a conformal phased array antenna, characterized in that, It includes an anti-collision host, a conformal phased array antenna connected to the anti-collision host, and a display and control device; The conformal phased array antenna serves as a receiving device for response signals; the conformal phased array antenna includes a left-wing antenna and a right-wing antenna; the left-wing antenna and the right-wing antenna are used to form required beams in the manner of digital phased array beamforming; among them, the superposition of all beams can cover 180° forward; the beams of the left-wing antenna and the right-wing antenna respectively cover 90° on the left side and 90° on the right side of the forward direction; The anti-collision host includes a PPC controller and an FPGA controller, which are used to complete interrogation coding, response decoding, monopulse angle measurement, target monitoring, and anti-collision warning processing under the control of the display and control device, and report the obtained target point track and anti-collision warning information to the display and control device; among them, the monopulse angle measurement refers to monopulse angle measurement based on the formation of sum / difference beams by the phased array; The display and control device is used to send control commands to the anti-collision host and display the target point track and anti-collision warning information reported by the anti-collision host; The working method of the forward airborne anti-collision system based on the conformal phased array antenna includes: (1) Interrogation beam scheduling: The display and control device controls the anti-collision host to start working, and the PPC controller periodically performs interrogation beam scheduling; (2) Interrogation coding: The FPGA controller performs coding for only C-mode and S-mode interrogations according to the commands issued by the PPC controller during interrogation beam scheduling; (3) Digital beamforming: When interrogating or not interrogating, the conformal phased array antenna forms transmit beams, receive beams, or omnidirectional beams through digital beamforming, and converts and outputs the digital I / Q signals of sum / difference beams; (4) Response decoding: The FPGA controller receives the digital I / Q signals of sum / difference beams, opens the corresponding response decoding switch according to the interrogation mode, performs response decoding according to the signal formats of C-mode and S-mode, extracts the C code of the target, S-mode data, amplitude / phase of sum / difference beams, and calculates the target distance at the same time, and forms original point trace data to be reported to the PPC controller for processing; (5) Monopulse angle measurement: The PPC controller uses the amplitude / phase of sum / difference beams in the original point trace data and calculates the target azimuth angle by using relevant algorithms of monopulse angle measurement; (6) Based on the real-time acquisition of target distance, target azimuth angle, C code, and S-mode data, the PPC controller completes the point track processing of the target, forms the track of the target and sends it to the display and control device for display; moreover, the PPC controller monitors the flight state of the target, combines the flight state of the aircraft itself, completes the judgment of the flight situation in the adjacent airspace, classifies the anti-collision threat level of the target, and outputs corresponding anti-collision warning information according to the anti-collision threat level classification and reports it to the display and control device for display; The process of the PPC controller periodically performing interrogation beam scheduling is as follows: The 90° ranges covered by the left-wing antenna and the right-wing antenna are respectively evenly divided into m beams, obtaining a total of 2m beams; among them, the beam center pointing intervals of the 2m beams are 90° / m, and the beam width is designed as (90° / m)×1.5; When only in C mode interrogation, within each period, the PPC controller arranges a whispering call sequence and conducts beam scheduling in sequence according to the order of beam 1 to beam 2m. When in S mode interrogation, within each period, the PPC controller determines the beam corresponding to the azimuth of each target to be interrogated according to the current S mode target information list, and then arranges the beams in sequence as S mode interrogation commands to conduct roll call interrogation on the S mode targets.

2. The forward airborne collision avoidance system based on a conformal phased array antenna according to claim 1, wherein Both the left-wing antenna and the right-wing antenna include N omnidirectional antenna elements.

3. The forward airborne anti-collision system based on a conformal phased array antenna according to claim 1, characterized in that, The display and control device includes a human-machine interaction interface.

4. The forward airborne anti-collision system based on a conformal phased array antenna according to claim 1, wherein The encoded output signals for conducting only C mode and S mode interrogation encoding include amplitude modulation encoded signal ASK, phase modulation encoded signal DPSK, power amplifier switch encoded signal AM, transceiver switching encoded signal TR, and decoding gate encoded signal YM_GATE.

5. The forward airborne anti-collision system based on a conformal phased array antenna according to claim 4, characterized in that The specific process of digital beamforming includes: When conducting only C mode or S mode interrogation, the conformal phased array antenna forms the required transmit beam and receive beam through digital beamforming according to the beam number of the current interrogation schedule; when TR = 1, the amplitude modulation encoded signal ASK and the phase modulation encoded signal DPSK are radiated through the transmit beam, and when TR = 0 and YM_GATE = 1, the response signal transmitted by the target is received through the receive beam, and the received response signal is converted to output the digital I / Q signals of the sum / difference channels. When no interrogation is being conducted, that is, when TR = 0 and YM_GATE = 0, an omnidirectional beam is formed through digital beamforming to detect the intermittent oscillation signal sent by the S mode target in the air, and the detected intermittent oscillation signal is converted to output the digital I / Q signals of the sum / difference channels.

6. The forward airborne collision avoidance system based on a conformal phased array antenna according to claim 5, characterized in that, The method of calculating the target azimuth angle using the relevant algorithm of monopulse angle measurement is: T m = T f + T Δ ; Among them, T m is the target azimuth angle, and T f is the azimuth angle of the beam center of the common phased array antenna relative to due north, and T Δ is the azimuth deviation of the target relative to the beam center of the common phased array antenna within the main lobe of the beam.

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