An integrated airborne air traffic monitoring system and method

Abstract

This invention achieves detection of non-cooperative aerial targets such as low, small, and slow aircraft by adding echo detection capabilities for the 1030MHz C / S mode interrogation signal and the 1090MHz C / S / ES mode reply signal. It also eliminates false ADS-B targets by integrating and judging the track information of non-cooperative targets, ADS-B track information, and TCAS track information. The solution uses software-defined radio technology to implement signal coding and modulation, frequency sorting, and signal analysis, achieving an integrated detection and identification design without significantly increasing the size, weight, or power consumption of existing hardware. This not only integrates and shares hardware resources, improving hardware utilization, but also allows for deep complementarity and fusion of detection and communication information, enabling efficient information exchange and significantly improving the system's cost-effectiveness. It also addresses the detection and identification of non-cooperative targets such as low, small, and slow aircraft and false ADS-B targets.

Description

Technical Field

[0001] The present invention belongs to the technical field of communication and detection, and in particular relates to an airborne air traffic monitoring system and method integrating communication and detection. Background Art

[0002] After the end of World War II, radar technology was rapidly adopted by civil aviation for use in monitoring and guiding various aircraft. During this period, airborne target surveillance relied primarily on the detection capabilities of ground-based primary radar. After decades of development, primary radar became primarily used for monitoring and tracking non-cooperative targets, becoming widely used in military aviation. In civil aviation, primary radar gradually became a necessary complement to secondary radar surveillance systems.

[0003] After the 1950s, with the application of friend-or-foe identification radar technology in the field of air traffic control, secondary radar systems (SSR) began to enter the civil aviation field, and finally, under the promotion of the International Civil Aviation Organization, the air traffic control radar beacon system (i.e. air traffic control transponder, ATC transponder) was developed, which is currently widely used in both military and civil aviation fields. It enables ground controllers to obtain the real-time identity, spatial position, speed, flight trend and other information of the aircraft from ground-to-air radar communications.

[0004] With increasing air traffic and the rise in aircraft collisions, the Federal Aviation Administration (FAA) formally proposed the functional requirements and technical definition for an airborne collision avoidance system in 1981, and developed and implemented the TCAS development plan. TCAS is an airborne traffic surveillance and collision avoidance system that operates independently of ground-based radio stations. Based on secondary radar, it transmits interrogation signals to the surrounding airspace. Target aircraft, using their ATC transponders, respond with information such as altitude and identity. The TCAS carrier aircraft measures the delay and bearing of the reply signals to determine the relative range and bearing of the target aircraft. The TCAS aircraft then displays the traffic situation in a specific three-dimensional airspace around the aircraft on the cabin display, allowing pilots to clearly understand the traffic situation in the airspace adjacent to their aircraft (this is limited to target aircraft equipped with ATC transponders). Airborne equipment began to monitor aerial targets.

[0005] In recent years, Automatic Dependent Surveillance-Broadcast (ADS-B) equipment has been gradually adopted by civil aviation. ADS-B is a new navigation technology that utilizes air-to-ground and air-to-air data communications for traffic monitoring and information transmission. It autonomously and periodically broadcasts information such as the position, status, and performance of aircraft. Upon reception by ground-based air traffic control stations or aircraft-mounted ADS-B IN equipment, the target aircraft's precise GPS position is obtained. Compared to radar systems, ADS-B provides more real-time and accurate surveillance information, including aircraft positions, with only approximately one-tenth the investment required, low maintenance costs, and a long service life. However, its technical barriers to entry are low, and it is susceptible to interference from false position broadcasts.

[0006] Since 2010, with the emergence of drones, these low-cost, compact aircraft have rapidly gained popularity and become widely used across various industries. However, this has also posed significant challenges to air traffic control and low-altitude flight operations. In particular, the safe and clear airspace surrounding airports is often subject to unauthorized intrusion by drones. These low-lying, small, and slow-moving targets are limited by cost, size, and payload, making it difficult to mandate the installation of ATC transponders. Furthermore, some illegal ADS-B Out devices exist, which can easily mislead aircraft on air routes, disrupting normal flight operations. These two issues are becoming new threats to flight safety.

[0007] Adding a detection system for low, small, and slow targets and suspicious ADS-B targets to the aircraft can complete the surveillance and tracking of non-cooperative targets and is an effective solution.

[0008] As people's awareness of aviation safety and functional requirements continues to improve, there are more and more airborne electronic equipment. Simply adding a new detection system will bring about shortcomings and problems such as space occupation, increased energy consumption, and deterioration of the electromagnetic environment, which will greatly affect the overall performance.

[0009] While communication and detection systems differ somewhat in functionality, hardware, and software, they also share many commonalities, such as operational feasibility, similar system architecture principles, and significant overlap in hardware resources. Therefore, it's possible to utilize the same hardware platform for both target detection and information transmission, making it feasible to integrate airborne detection systems with secondary radar surveillance systems to a certain extent.

[0010] With the continuous development of information technology, especially the development of electronic components such as FPGA, high-speed ADC, high-speed DAC and software radio technology, the integrated development of detection and communication fields has brought unlimited possibilities.

[0011] Integrating the primary radar system, which detects non-cooperative targets such as low, small, and slow, suspicious targets, with the air traffic control surveillance system (primarily ATC transponders, TCAS, ADS-B, and AESS) that monitors cooperative targets, not only consolidates and shares hardware resources, improving hardware utilization, effectively reducing platform size, and lowering power consumption, but also enables deep information complementation and fusion, enabling efficient information exchange and significantly improving system cost-effectiveness. Therefore, utilizing software-defined radio technology to achieve integrated detection and communication in airborne surveillance equipment is of great significance. Summary of the Invention

[0012] The purpose of the present invention is to address the problems in the background technology and propose an integrated airborne air traffic surveillance system and method. Without significantly increasing the hardware volume, weight, and power consumption of existing airborne air traffic control surveillance systems (mainly integrated systems such as TCAS and air traffic integrated surveillance systems), the system solves the problem of detecting and identifying non-cooperative targets such as low, small, and slow targets in the air and ADS-B false targets.

[0013] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions to achieve it.

[0014] A software radio-based integrated sounding airborne air traffic monitoring system comprises an antenna, a radio frequency component, a signal processing component and a data processing component.

[0015] The signal processing components are generally implemented using the architecture of high-speed ADC, DAC, FPGA, and DSP / ARM. The ADC and DAC complete the analog-to-digital or digital-to-analog conversion of the data, and the FPGA and DSP / ARM jointly complete the signal encoding, decoding, echo detection and other functions. The data processing components can generally be designed using CPUs such as PowerPC and ARM, and mainly complete the detection of aerial targets, track establishment and maintenance, target fusion, collision detection and collision avoidance processing and other functions. The signal processing components and data processing components can also be integrated and designed, using high-performance fusion chips.

[0016] The antenna is a directional antenna used by the original TCAS, or a comprehensive antenna shared by TCAS, transponders, ADS-B and other equipment, and has the ability to receive multiple channels simultaneously.

[0017] The RF component is controlled by the signal processing component. In the transmitting state, it modulates and amplifies the interrogation signal, response signal, and broadcast signal at a specific frequency based on the coded information from the signal processing component's coding module, and then outputs the transmit signal to the antenna. In the receiving state, it receives 1030MHz and 1090MHz RF signals from the antenna, demodulates them, and outputs a broadband intermediate frequency signal to the decoding and echo detection module of the signal processing component. The physical entity of the RF component can be the RF transceiver of a TCAS system; it can also be the transponder transmitter and TCAS receiver; or it can be the integrated RF processing component of a comprehensive system such as T3CAS.

[0018] The signal processing unit's encoding module primarily receives control information and airborne data from the data processing unit, encodes the original TCAS, transponder, and ADS-B transmission signals, and after DAC conversion, sends them to the RF unit for modulation. The physical entity can be the signal processing unit of the TCAS system, the transponder, or a comprehensive system such as T3CAS.

[0019] The decoding and echo detection module of the signal processing component receives multiple channels (generally 4 channels for the upper antenna and 4 channels for the lower antenna) of broadband intermediate frequency signals after RF demodulation and ADC conversion. It uses software radio technologies such as extraction, multi-phase filtering, and orthogonal demodulation to complete the frequency sorting and pulse position / width / amplitude identification of 1030M / 1090MHz signals from the broadband intermediate frequency signals. It then performs echo detection based on the frequency characteristics and signal characteristics of the previous transmitted signal, and decodes the communication frequency band required for the current cycle. For example, after the system transmits a 1030 MHz signal for a Mode C / S interrogation and while waiting to receive a reply signal, it performs echo detection on the sorted 1030 MHz ± 0.2 MHz signal and decodes the sorted 1090 MHz ± 3 MHz Mode C / S / ES reply signal. Alternatively, in the listening state after a transponder / ADS-B signal is transmitted, it performs intermittent oscillation signal decoding, ADS-B IN decoding, and echo detection on the frequency-sorted 1090 MHz ± 3 MHz signal, and decodes the interrogation signal on the frequency-sorted 1030 MHz ± 0.2 MHz signal. Alternatively, in the receiving state immediately following a TCAS broadcast, it performs echo detection on the sorted 1030 MHz ± 0.2 MHz signal and decodes the sorted 1090 MHz ± 3 MHz Mode S / ES signal. The physical entity can be the signal processing component of the TCAS system or a signal processing component of an integrated system such as the AESS.

[0020] During echo detection, a power threshold is set to detect pulse characteristics and pulse sequences only for signals above the threshold: P1, P3, and P4 of the Mode C interrogation signal; P1 and P2 of the Mode S interrogation signal; F1 and the first valid pulse information bit of the Mode C reply signal; and P1, P2, P3, and P4 of the Mode S / ES reply / broadcast signal. Echo detection generates data such as the slant range between the aircraft and the target, the amplitude of the sum / difference channels of the echo signal, and the phase of the sum / difference channels. This data, along with the decoding results, is transmitted to the data processing unit for target track establishment and maintenance.

[0021] The data processing component receives the onboard information of the carrier aircraft and performs various tasks according to its inherent logic. The TCAS monitoring, air traffic control response, and ADS-B functions are not the innovations of this invention and will not be described in detail. However, the establishment and maintenance of the track of non-cooperative targets detected by the echo and its fusion with the track of the secondary radar monitoring target are one of the innovations of this invention.

[0022] The establishment and maintenance process of non-cooperative target tracks is as follows: Figure 4 As shown in the figure. First, in each monitoring cycle, all echo signals acquired in that cycle are sorted and fused. Two or more echo signals that meet the echo signal range, power threshold, slant range threshold, and azimuth threshold are fused. The slant range of the fused echo signal uses the latest echo slant range, and the azimuth uses the average of multiple source signals. Then, the echo signals are sequentially tested for power, slant range, and azimuth with the established non-cooperative target tracks in order from near to far. The established non-cooperative target track is updated using the echo signals that meet the correlation requirements, and the used echo signals are deleted from the echo signal list. If no non-cooperative target track has been established, no track update is required. Then, the echo signals that have not met the non-cooperative target track update requirements for three consecutive cycles are tested for correlation to check whether there are three echo signals that meet the conditions for establishing a new non-cooperative target track. If so, a new track is established; otherwise, the next step is carried out. Then, a check is made to see if there is any non-cooperative target track information that has not been updated for a long time. If so, the track is deleted.

[0023] The track fusion scheme for non-cooperative targets (targets detected by echo) and TCAS targets and ADS-B targets is described below.

[0024] First, the tracks of targets tracked by TCAS and ADS-B are fused according to RTCA DO-300. The fused track is equivalent to the TCAS track, and the corresponding tracks are marked as relevant. Then, the TCAS tracks, ADS-B tracks, and non-cooperative target tracks are sorted from far to near according to slant range.

[0025] If there are relevant tracks that have been fused in previous surveillance cycles, the two tracks that still meet the track correlation criteria are prioritized for fusion. If track fusion has not been performed in previous surveillance cycles, non-cooperative targets whose differences in slant range, relative bearing, and relative speed are fused with TCAS tracks within a certain threshold, and the corresponding tracks are marked. The fused non-cooperative target tracks will still be tracked and maintained independently in subsequent cycles, but will no longer be used for subsequent correlation checks in this cycle. Finally, ADS-B target and non-cooperative target tracks that are uncorrelated with TCAS tracks will be checked for correlation and fused based on slant range, relative bearing, and relative speed information, and the corresponding tracks will be marked. The non-cooperative target tracks that were fused will also still be tracked and maintained independently in subsequent cycles. If there are ADS-B targets within the warning range that are uncorrelated with both TCAS and non-cooperative target tracks for consecutive cycles, the ADS-B target is deemed a false target.

[0026] Non-cooperative target tracks that are not used for track fusion can be considered as targets that are not equipped with ATC transponder equipment and ADS-B equipment, and can be used for target output to prompt pilots.

[0027] By adding echo detection capabilities to existing TCAS, ATC transponders, ADS-B, or other integrated systems, the system can detect surrounding aerial targets. By comparing the detection results with target track information obtained through communication, false ADS-B targets can be eliminated and non-cooperative targets monitored. Software-defined radio technology is used to process the broadband intermediate frequency (IF) of 1030MHz and 1090MHz signals, innovatively implementing echo detection and communication functions on the same airborne aerial target surveillance hardware platform. This improves hardware utilization and reduces system hardware size, weight, power consumption, and complexity. A new process for establishing and maintaining tracks for non-cooperative targets has been designed, along with a proposed method for establishing and maintaining tracks for echo signals from non-cooperative targets. A process has been developed to fuse the tracks of non-cooperative targets detected by echo with the existing tracks of targets monitored by TCAS and ADS-B targets, thereby eliminating false ADS-B targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of an implementation scenario provided for an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of another implementation scenario provided for an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of a system structure provided by an embodiment of the present invention;

[0031] Figure 4 A schematic diagram of a process for establishing and maintaining a non-cooperative target track detected by echo according to an embodiment of the present invention;

[0032] Figure 5 A schematic diagram of the track fusion process of a TCAS target, an ADS-B target, and a non-cooperative target is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make the technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0034] Example 1: Figure 1 Shown is a schematic diagram of an implementation scenario of the present invention.

[0035] Step 1: A TCAS system or a TCAS-enabled integrated system 1 using an integrated sounding solution sends a 1030 MHz Mode C interrogation signal and then enters the receiving state.

[0036] Step 2: The interrogation signal is reflected by the surrounding cooperative target 2 and non-cooperative target 3;

[0037] Step 3: Target 2 sends a 1090 MHz Mode C response to the Mode C interrogation signal.

[0038] Step 4: System 1 successively receives the 1030 MHz echo signals reflected from targets 2 and 3, as well as the 1090 MHz C-mode response from target 2.

[0039] Step 5: The RF component of system 1 performs broadband intermediate frequency demodulation on the received signal. The signal processing component uses software radio technology to complete frequency sorting, compares the original 1030M±0.2MHz signal sorted out with the pulse characteristics and pulse sequence of the frame pulses P1, P3, and P4 to perform echo detection, and decodes the original 1090M±3MHz Hz signal into a C-mode response signal; and reports the results to the data processing component.

[0040] Step 6: Repeat steps 1 to 5 continuously. The data processing component establishes the track of the non-cooperative target and the track of the C-mode cooperative target based on the echo signals and response signals of the continuous cycle, and performs track fusion, maintenance and other processing.

[0041] Example 2: Figure 2 Shown is another implementation scenario schematic diagram provided by the present invention

[0042] Step 1: A TCAS system or a TCAS-enabled integrated system 1 using an integrated sounding solution sends a 1030 MHz Mode S interrogation signal and then enters the receiving state.

[0043] Step 2: The interrogation signal is reflected by the surrounding cooperative target 2 and non-cooperative target 3;

[0044] Step 3: Target 2 sends a 1090 MHz Mode S reply to the Mode S interrogation signal.

[0045] Step 4: System 1 successively receives the 1030 MHz echo signals reflected from targets 2 and 3, as well as the 1090 MHz S-mode response from target 2.

[0046] Step 5: The RF component of system 1 performs broadband intermediate frequency demodulation on the received signal. The signal processing component uses software radio technology to complete frequency sorting. The sorted original 1030M±0.2MHz signal is compared with the pulse characteristics and pulse sequence 1.25us before the frame pulses P1, P2, and P6 to perform echo detection. The sorted original 1090M±3MHz Hz signal is decoded into the S-mode reply signal; and the results are reported to the data processing component.

[0047] Step 6: Repeat steps 1 to 5 continuously. The data processing component establishes the track of the non-cooperative target and the track of the S-mode cooperative target based on the echo signals and response signals of the continuous cycle, and performs track fusion, maintenance and other processing.

[0048] Example 3: Figure 3 Shown is a schematic diagram of a system structure provided by the present invention

[0049] The figure shows an integrated air traffic surveillance system equipped with TCAS, ATC transponder, and ADS-B capabilities. The system comprises component 1 (data processing unit), component 2 (signal processing unit), component 3 (RF unit), and component 4 (two L-band directional antennas). The primary hardware architecture for components 1 and 2 is FPGA + CPU, but a fusion chip can also be used for integrated design. This specific embodiment is only an example of a hardware architecture and is not intended to be limiting.

[0050] Component 4 consists of two antennas, one above and one below, each connected to component 3 via four RF cables, performing both 1030MHz and 1090MHz signal reception and transmission. Components 1, 2, and 3 can be housed in a single chassis. Component 3 connects to component 4 via eight RF cables. Component 3 demodulates the eight channels of wireless signals received from component 4 using broadband intermediate frequency (IF) modulation and outputs them to components 2-4 via the eight RF cables. Component 3 also receives coded and control information from component 2, modulates and amplifies the signals, and then outputs them to component 4. Component 2-4 converts the received signals into analog-to-digital form and transmits them to component 2-2 for software-defined radio (SDR) analysis. Component 2-2 performs echo detection and signal decoding, reporting the results to component 1. Component 2 receives data and control information, operates in different modes, and performs corresponding signal encoding and control functions for component 3. Component 1 logically arranges the operating state of component 2, transmits the data required for its operation, and receives analysis data from component 2-2, performing tasks such as track fusion, tracking and maintenance, and false target detection.

[0051] Example 4: Figure 4 The figure shows a schematic diagram of the process of establishing and maintaining a non-cooperative target track using echo detection provided by the present invention.

[0052] Step 1: Get all echo signal information of this cycle;

[0053] Step 2: Sorting echo signals. In each monitoring cycle, all echo signals acquired in this cycle are sorted. The sorting can be from near to far or from far to near. The sorting from near to far is recommended.

[0054] Step 3: Echo signal fusion. Two or more echo signals that meet the echo signal range, power threshold, slant range threshold, and azimuth threshold are fused. The slant range of the fused echo signal uses the latest echo slant range, and the azimuth uses the average of multiple source signals.

[0055] Step 4: Update non-cooperative target tracks. Perform correlation tests on the power, slant range, and azimuth of the echo signals against the established non-cooperative target tracks, in order from nearest to farthest. Use the echo signals that meet the correlation requirements to update the established non-cooperative target tracks, and delete the used echo signals from the echo signal list. If no non-cooperative target tracks have been established, no track update is required, skip step 4, and proceed to step 5.

[0056] Step 5: Establish a new track for the non-cooperative target. All echo signals that do not meet the non-cooperative target track update requirements for three consecutive cycles are subjected to correlation tests based on the power threshold, slant range threshold, and azimuth threshold to check whether there are three echo signals that meet the non-cooperative target new track establishment conditions. If so, a new track is established; otherwise, proceed to the next step.

[0057] Step 6: Check whether there is any non-cooperative target track information that has not been updated for a long time. If so, delete the track.

[0058] Example 5: Figure 5 The figure shows a flow chart of track fusion of TCAS target, ADS-B target and non-cooperative target provided by the present invention.

[0059] S1: Obtain all non-cooperative target track lists, TCAS surveillance track lists, and ADS-B IN track lists;

[0060] S2: Fuse the TCAS surveillance track list and ADS-B IN track list according to RTCA DO-300 standards, and classify the fused targets as TCAS tracks;

[0061] S3: credibly mark the fused ADS-B target;

[0062] S4: Sort TCAS tracks, ADS-B tracks, and non-cooperative target tracks within the warning distance (e.g., 5 km) by slant range from near to far.

[0063] S5: Determine whether the correlation detection of all targets within the warning distance has been completed. If completed, proceed to S34; if not, proceed to S6;

[0064] S6: Whether the current track has been marked as a relevant track. If so, proceed to S7; if not, proceed to S17.

[0065] S7: Determine whether the two data marked as correlation tracks meet the correlation test in this cycle; if yes, proceed to S8; if not, proceed to S11;

[0066] S8: Determine whether the TCAS track or ADS-B track is updated in this cycle. If so, proceed to S9; if not, proceed to S10.

[0067] S9: After fusion, use TCAS or ADS-B track information for output display, and then enter S5;

[0068] S10: Fuse the two tracks, use the minimum value for slant distance and the average value for azimuth, output and display, and then enter S5;

[0069] S11: Whether the track correlation is lost for three consecutive cycles. If so, go to S12; otherwise, go to S15;

[0070] S12: The two types of tracks are not fused;

[0071] S13: cancel the correlation mark of the two tracks;

[0072] S14: Output TCAS or ADS-B track, then enter S5;

[0073] S15: Update the track correlation cycle count and update the loss correlation cycle count;

[0074] S16: Output TCAS or ADS-B track, then enter S5;

[0075] S17: Is there a TCAS target that meets the track correlation? If yes, proceed to S32; if not, proceed to S18;

[0076] S18: Is there an ADS-B target that meets the track correlation? If yes, proceed to S19; if not, proceed to S24;

[0077] S19: Is it marked as a false ADS-B target? If yes, proceed to S20; if not, proceed to S22;

[0078] S20: Reduce the false probability of the corresponding ADS-B track information;

[0079] S21: Is the false probability of the ADS-B track information marked as false 0? If so, proceed to S23; if not, proceed to S22;

[0080] S22: Output the non-cooperative target track and then enter S5;

[0081] S23: marking the corresponding ADS-B track information and non-cooperative target track information for relevance;

[0082] S24: Output ADS-B track information, then enter S5;

[0083] S25: Is it a non-cooperative target? If not, go to S26; if yes, go to S32;

[0084] S26: Check whether the ADS-B target has entered the warning range. If yes, proceed to S27; if not, proceed to S30.

[0085] S27: Count the false cycles of the ADS-B target and then proceed to S28;

[0086] S28: Whether it exceeds the ADS-B false target determination boundary, if yes, proceed to S29; if not, proceed to S30;

[0087] S29: The ADS-B track is marked as a false track and is not displayed. Then the program goes to S5.

[0088] S30: Display ADS-B track information, then enter S5;

[0089] S31: Display the non-cooperative target track information, and then enter S5;

[0090] S32: Mark the corresponding track for relevance, and then enter S33;

[0091] S33: Fuse the two related tracks, use TCAS track information and output for display, then enter S5;

[0092] S34: The process ends.

[0093] The technical solution adopted by the present invention does not add a new detection signal modulation method. The detection signals used are all frame pulse signals in the original TCAS and ATC transponder communication signals, which will not interfere with the original functions of the system. At the same time, a software radio demodulation and decoding solution is adopted. It only needs to add corresponding software radio signal processing software modules to the original logic circuits, processors and other hardware, which will not cause a significant increase in the overall volume, weight and power consumption of the system. More importantly, by adding an echo detection function, it can actively detect close-range ADS-B targets and non-cooperative low, small and slow targets, which can effectively eliminate ADS-B false targets, increase the probability of monitoring and detecting non-cooperative targets, and improve the pilot's perception of air traffic conditions.

[0094] The present invention realizes the detection of non-cooperative aerial targets such as low, small, and slow aircraft by adding the echo detection function of the 1030MHz C / S mode inquiry signal and the 1090MHz C / S / ES mode reply signal; and eliminates false ADS-B targets by judging the track fusion of non-cooperative target track information, ADS-B track information, and TCAS track information. The solution adopts software radio technology to realize signal coding modulation, frequency sorting, signal analysis and other functions, and realizes an integrated detection design without significantly increasing the volume, weight, and power consumption of existing hardware. It can not only integrate and share hardware resources to improve hardware utilization, but also deeply complement and integrate detection information and communication information, realize information exchange efficiently, greatly improve the cost-effectiveness of the system, and solve the problem of detecting and identifying non-cooperative targets such as low, small, and slow aircraft and ADS-B false targets.

Claims

1. An integrated airborne air traffic surveillance system, characterized in that: The system includes: an antenna, a radio frequency component, a signal processing component and a data processing component connected in bidirectional communication; the signal processing component includes: an encoding module, a decoding and echo detection module, a DAC and an ADC; The RF component is controlled by the signal processing component. In the transmitting state, it modulates and amplifies the specific frequency inquiry signal, response signal, and broadcast signal according to the coding information of the signal processing component coding module, and outputs the transmission signal to the antenna. In the receiving state, it receives 1030MHz and 1090MHz RF signals from the antenna, demodulates them, and outputs broadband intermediate frequency signals to the decoding and echo detection module of the signal processing component. The encoding module of the signal processing component receives the control information and airborne data information of the data processing component, completes the encoding of the original TCAS, transponder, and ADS-B transmission signals, and after DAC conversion, sends them to the radio frequency component for modulation; The decoding and echo detection module of the signal processing component receives the broadband intermediate frequency signal after multi-path RF demodulation and ADC conversion. It uses software radio technology to complete the frequency sorting and pulse position / width / amplitude identification of 1030M / 1090MHz signals from the broadband intermediate frequency signal. It then performs echo detection on the frequency characteristics and signal characteristics of the previous transmitted signal and decodes the communication frequency band required for the current cycle. The data processing unit performs echo detection, establishes and maintains non-cooperative target tracks, and fuses the non-cooperative target tracks with the tracks of secondary radar surveillance targets. Secondary radar surveillance targets are TCAS targets equipped with ATC transponders and ADS-B OUT equipment, or ADS-B targets equipped only with ADS-B OUT equipment. After the system sends out a 1030MHz signal for C / S mode inquiry, while waiting to receive the response signal, the decoding and echo detection module of the signal processing component performs echo detection on the sorted 1030M±0.2MHz signal and performs C / S / ES mode response signal decoding on the sorted 1090M±3MHz Hz signal; In the listening state after the transponder / ADS-B signal is transmitted, the decoding and echo detection module of the signal processing component performs intermittent oscillation signal decoding, ADS-B IN decoding and echo detection on the frequency-sorted 1090M±3MHz signal, and performs interrogation signal decoding on the frequency-sorted 1030M±0.2MHz signal. In the receiving state immediately following the TCAS broadcast, the decoding and echo detection module of the signal processing component performs echo detection on the detected 1030M±0.2MHz signal and decodes the detected 1090M±3MHz signal for S / ES mode signal processing. When the decoding of the signal processing component and the echo detection module detect the echo, The power threshold is set, and pulse characteristics and pulse sequence detection are performed on P1, P3, and P4 of the C-Mode interrogation signal, P1 and P2 of the S-Mode interrogation signal, F1 and the first valid pulse information bit of the C-Mode reply signal, and P1, P2, P3, and P4 of the S / ES-Mode reply / broadcast signal that are above the threshold value. The slant range information between the carrier aircraft and the target, the amplitude information of the sum channel / difference channel of the echo signal, the phase information of the sum channel / difference channel, and the decoding result formed after echo detection are sent to the data processing unit to establish and maintain the target track.

2. The airborne air traffic surveillance system with integrated detection according to claim 1, characterized in that: The antenna is a directional antenna used by the original TCAS, or a comprehensive antenna shared by TCAS, transponder, and ADS-B equipment, capable of multi-channel simultaneous reception. The signal processing component is implemented using the architecture of high-speed ADC, DAC, FPGA, and DSP / ARM. The ADC and DAC complete the analog-to-digital or digital-to-analog conversion of the data, and the FPGA and DSP / ARM jointly complete signal encoding, decoding, and echo detection. The data processing component is designed using PowerPC and ARM to complete the detection of aerial targets, track establishment and maintenance, target fusion, collision detection, and collision avoidance processing. The signal processing component and the data processing component can also be integrated and implemented using high-performance fusion chips.

3. The airborne air traffic surveillance system with integrated detection according to claim 1, characterized in that: The process of the data processing component establishing the non-cooperative target track based on the echo signal: S11, in each monitoring cycle, all echo signals acquired in the cycle are sorted and merged, and two or more echo signals that meet the echo signal range, power threshold, slant range threshold, and azimuth threshold are merged. The slant range of the fused echo signal uses the latest echo slant range, and the azimuth uses the average value of multiple source signals; S12, performing correlation tests on the power, slant range, and azimuth of the echo signals with the established non-cooperative target tracks in order from near to far. The echo signals that meet the correlation requirements are used to update the established non-cooperative target tracks, and the used echo signals are deleted from the echo signal list. If no non-cooperative target tracks have been established, no track update is required. S13, performing correlation detection on the echo signals that do not meet the non-cooperative target track update requirements for N consecutive periods to check whether there are M echo signals that meet the non-cooperative target new track establishment conditions. If so, a new track is established; otherwise, proceed to the next step; M and N are preset values and are equal; S14, checking whether there is non-cooperative target track information that has not been updated for a long time, and if so, deleting the track.

4. The airborne air traffic surveillance system with integrated detection according to claim 3, characterized in that: The data processing component integrates the tracks of non-cooperative targets, TCAS targets, and ADS-B targets as follows: S21: The tracks of targets tracked by TCAS and ADS-B are fused according to RTCA DO-300. The fused tracks are equivalent to the TCAS tracks, and the corresponding tracks are marked as relevant. The TCAS tracks, ADS-B tracks, and non-cooperative target tracks are then sorted from far to near according to slant range. S22: If there are relevant tracks that have been fused in the previous monitoring cycle, the two tracks that still meet the track correlation conditions are preferentially used for fusion; if track fusion has not been performed in the previous monitoring cycle, the non-cooperative targets whose differences in slant range, relative bearing, and relative speed are within a certain threshold are fused with the TCAS track, and the corresponding tracks are marked; S23: Perform correlation detection and track fusion on ADS-B targets and non-cooperative targets that have no correlation with TCAS tracks based on slant range, relative bearing, and relative speed information, and mark the corresponding tracks; S24: If within the warning distance, there are still ADS-B targets that have no correlation with either the TCAS track or the non-cooperative target track in consecutive cycles, the ADS-B target can be determined to be a false target.

5. The airborne air traffic surveillance system with integrated detection according to claim 4, characterized in that: In S22 and S23, the non-cooperative target tracks used for fusion need to be maintained and updated using echo signals.

6. The airborne air traffic surveillance system with integrated detection according to claim 4, characterized in that: Non-cooperative target tracks that are not used for track fusion can be considered as targets that are not equipped with ATC transponders and ADS-B equipment.

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