ADS-B signal generation system and method

Abstract

The present invention discloses a system for generating an ADS-B signal, comprising: a signal generating unit, a signal detecting unit, a signal sending unit, and a pressure supply unit; the signal generating unit is used to obtain signal information; the signal detecting unit is used to detect the signal information and obtain an ADS-B reply signal; the signal sending unit is used to output the ADS-B reply signal; the pressure supply unit is used to provide a working voltage to the signal generating unit and the signal detecting unit. The present invention can use the ADS-B system and method as a virtual radar to provide a control function, combine the S-mode secondary radar with the ADS-B technology, and realize that the aircraft continuously broadcasts its own address code, altitude, longitude and latitude and other information during the flight, thereby improving the safety performance of the traffic control system and method.

Description

Technical Field

[0001] The present invention relates to the technical field of ADS-B systems and methods, and in particular to a system and method for generating an ADS-B signal. Background Art

[0002] As the times progress and technology becomes more mature, people are demanding more and more efficiency. As the representative of transportation speed, civil aviation, aviation transportation-related industries are also occupying an increasingly large proportion in society, and the requirements for them are becoming more stringent.

[0003] Currently, air traffic control is one of the most important links in the aviation transportation-related industries, and the core equipment of air traffic control is radar. However, radar has the defects of high construction cost and cannot be deployed in any area. Therefore, radar-based air traffic control technology is not only costly and cannot be widely used, but also once the aircraft flies across the ocean, its posture and trajectory will not be captured.

[0004] The ADS-B system and method, which has both communication and surveillance functions, is the best alternative. It can transmit information such as location information including longitude and latitude and heading, conflict warning information, track angle information and aircraft identification information. Therefore, how to generate ADS-B signals is of great significance to the safety and stability of aviation transport-related industries. Summary of the invention

[0005] In view of the above problems, the present invention proposes a system and method for generating ADS-B signals to solve the technical problems existing in the prior art. The ADS-B system and method can be used as a virtual radar to provide control functions, and the S-mode secondary radar and ADS-B technology are combined to enable the aircraft to continuously broadcast its own address code, altitude, longitude and latitude and other information during the flight, thereby improving the safety performance of the traffic control system and method.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides an ADS-B signal generation system, comprising: a signal generation unit, a signal detection unit, a signal transmission unit, and a pressure supply unit;

[0008] The signal generating unit is used to obtain signal information;

[0009] The signal detection unit is used to detect the signal information and obtain the ADS-B reply signal;

[0010] The signal sending unit is used to output the ADS-B reply signal;

[0011] The voltage supply unit is used to provide working voltage to the signal generating unit and the signal detecting unit.

[0012] Preferably, the signal generating unit includes a central control module, a voltage conversion module, a radio frequency switch module, and a signal source module;

[0013] The voltage conversion module is used to convert the voltage provided by the pressure supply unit into the working voltage of the central control module;

[0014] The signal source module is used to generate a high-frequency signal source of 1090 MHz;

[0015] The central control module is used to output radio frequency switch control instructions;

[0016] The radio frequency switch module is used to perform a signal on-off operation according to the radio frequency switch control instruction to obtain the signal information.

[0017] Preferably, the operating voltage of the central control module is 3.3V.

[0018] Preferably, the signal source module adopts a secondary radar high-frequency signal generator.

[0019] Preferably, the signal detection unit adopts a radio frequency logarithmic detector.

[0020] Preferably, the voltage supply unit includes a first voltage source, a second voltage source, and a third voltage source;

[0021] The first voltage source is used to provide an operating voltage to the voltage conversion module;

[0022] The second voltage source is used to provide a working voltage to the RF switch module;

[0023] The third voltage source is used to provide an operating voltage to the radio frequency logarithmic detector.

[0024] Preferably, the first voltage source and the second voltage source are both 5V voltage sources; and the third voltage source is a 7V voltage source.

[0025] A method for generating an ADS-B signal comprises the following steps:

[0026] S1. Obtain signal information;

[0027] S2. Detect the signal information to obtain an ADS-B response signal;

[0028] S3. Output the ADS-B response signal.

[0029] Preferably, the step S2 also includes heading calculation, airspeed calculation, altitude calculation, and longitude and latitude calculation before the detection.

[0030] Preferably, the ADS-B reply signal is a pulse sequence.

[0031] The present invention discloses the following technical effects:

[0032] The present invention can use the ADS-B system and method as a virtual radar to provide control functions, and combine the S-mode secondary radar with the ADS-B technology to enable the aircraft to continuously broadcast its own address code, altitude, longitude and latitude and other information during flight, which is convenient for ground tracking and supervision, and has a low application cost. It can cover a larger area of ​​aviation transportation-related industries, which helps to further improve the safety rate of aircraft and improve the safety performance of the traffic control system and method. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] Figure 1 is a flow chart of the system and method of the present invention;

[0035] Figure 2 is a schematic diagram of overall circuit connection in an embodiment of the present invention;

[0036] Figure 3 A flow chart of a signal generating method in an embodiment of the present invention;

[0037] Figure 4 This is a flowchart of the CA field program in an embodiment of the present invention;

[0038] Figure 5 This is a flowchart of the AA field program in an embodiment of the present invention;

[0039] Figure 6 This is a flowchart of the ME field air speed information program in an embodiment of the present invention.

[0040] Figure 7 This is a flowchart of the ME field air location information program in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Reference Figure 1 As shown, this embodiment provides a system and method for generating an ADS-B signal, including: a signal generating unit, a signal detecting unit, a signal sending unit, and a pressure supply unit.

[0044] The signal generating unit is used to obtain signal information; the signal detecting unit is used to detect the signal information and obtain the ADS-B response signal; the signal sending unit is used to output the ADS-B response signal; and the pressure supply unit is used to provide working voltage to the signal generating unit and the signal detecting unit.

[0045] Among them, the signal generating unit includes a central control module, a voltage conversion module, a RF switch module, and a signal source module; the voltage conversion module is used to convert the voltage provided by the voltage supply unit into the working voltage of 3.3V of the central control module; the signal source module is used to generate a high-frequency signal source of 1090MHz; the central control module is used to output RF switch control instructions; the RF switch module is used to perform signal on-off operations according to the RF switch control instructions to obtain signal information.

[0046] The voltage supply unit includes a first voltage source, a second voltage source, and a third voltage source; the first voltage source is used to provide a working voltage to the voltage conversion module; the second voltage source is used to provide a working voltage to the RF switch module; and the third voltage source is used to provide a working voltage to the RF logarithmic detector. The first voltage source and the second voltage source are both 5V voltage sources; the third voltage source is a 7V voltage source.

[0047] In this embodiment, a secondary radar high-frequency signal generator is used to generate a 1090MHz high-frequency signal source, and an S-mode output response signal is generated through a hardware control circuit. At the same time, a pulse of a certain width is displayed under the cooperation of the power supply circuit, the peripheral clock, and the software control program. The overall circuit diagram of the S-mode hardware control circuit design is shown in the figure below. Figure 2 As shown in the figure, the signal generation module in the circuit mainly includes the serial port, voltage conversion module, core microcontroller chip STM32F756ZGTx of the drive control circuit, and RF switch chip HMC336MS8G; the signal detection unit uses a RF logarithmic detector. In addition, the circuit is also connected to a serial port module and a download port module, where the serial port is USART1, and the PL2303 USB to serial port download line is used. The download port module is SWD, which occupies fewer interfaces and saves resources.

[0048] In this circuit, the voltage conversion module uses the AMS1117--3.3 chip, which is a high-efficiency linear voltage regulator with three-terminal adjustable or fixed output voltage of 3.3V, and the error accuracy can reach within 1%. Since the AMS1117-3.3 also integrates overheat protection and current limiting circuits, it is very suitable for use in the power supply voltage stabilization circuit of small chips.

[0049] After the circuit schematics of each module are designed, they are connected into an overall circuit schematic. Then the schematic is electrically checked and compiled to check whether it is correct. If it is incorrect, it is adjusted. Finally, the overall hardware circuit diagram is formed. The circuit is placed on two PCB boards. Since the RF switch chip is easily affected by other interferences and the routing curvature of the signal line of the RF switch cannot be too large, we place the RF switch separately on a PCB circuit board.

[0050] After that, the ADS-B transmitter position-related data is sent through the serial port. When the single-chip microcomputer receives the data sent by the serial port, it needs to compare the first bit of data received with the frame header FF. If they are different, it indicates that the data sent is wrong and no subsequent operations are required. The function of the frame header is to prevent redundant data from interfering with the information and forming erroneous collection, and to prevent the input of erroneous data and delay the operation of the system and method. If they are the same, the second bit of data received will continue to be judged. When the second bit of data received is 19 (that is, indicating that the information sent is ADS-B air speed information), the received data is calculated according to the requirements of the air speed information and a pulse sequence is generated. After that, the pulse sequence just generated is transmitted through the control switch; when the second bit of data received is 0, 9~18, 20~22 (that is, indicating that the information sent is ADS-B air position information), the received data is calculated according to the requirements of the air position information and a pulse sequence is generated. After that, the pulse sequence just generated is transmitted through the control switch. The data sent to the PC through the serial port can be observed through the serial port debugging assistant to facilitate verification to determine whether the algorithm in the program is correct. Figure 3 shown.

[0051] Next, the above method is used to analyze the bit segments of the ADS-B message, such as Figure 4 As shown, first, the program in the MCU needs to be initialized, and then the data about the CA field is sent to the MCU through the serial port. After the MCU receives the data sent by the serial port, it needs to compare the first received data with the frame header FF. If they are different, wait for the serial port to resend the data. If they are the same, store the received data in the 22nd to 24th bits of the fixed array, and then generate a pulse sequence according to the fixed array and send it out through the control switch.

[0052] Next, analyze the AA field, such as Figure 5 As shown, the program is first initialized, and then the data of the AA field used to represent the globally unique ICAO address position of the transmitter device is sent to the microcontroller through the serial port. After the microcontroller receives the data sent by the serial port, it is necessary to compare the first received data with the frame header FF. If they are different, wait for the serial port to resend the data. If they are the same, the received data is stored in the 25th to 48th bits of the fixed array, and then a pulse sequence is generated according to the fixed array and sent out through the control switch.

[0053] Finally, the ME field is analyzed. In this embodiment, the ME field information is divided into two types, one is air speed information, and the other is air position information. The following is a process analysis of the air speed information:

[0054] First, initialize the program, and then send the ME field data used to indicate the heading and speed of the transmitter device to the single-chip microcomputer through the serial port. After the single-chip microcomputer receives the data sent by the serial port, it needs to compare the first bit of data received with the frame header FF. If they are different, wait for the serial port to resend the data. If they are the same, continue to judge the second bit of data. If the second bit of data does not indicate the airspeed, it is calculated using the algorithm of the air position. If it indicates the airspeed, the corresponding data is calculated according to the heading and airspeed related algorithms, and is placed in the 49-104 bits of the fixed array. Then, a pulse sequence is generated according to the fixed array and sent out through the control switch.

[0055] The heading and airspeed related algorithms are as follows: for an aircraft in the air, the earth is approximately a sphere. In order to more accurately determine the specific position of the aircraft, the earth is first divided into different numbered areas (Zones) according to longitude and latitude, and then each zone is divided into different bins at equal distances. The latitude zone width is the same, while the longitude zone width varies with the latitude. The longitude zone width near the equator is the smallest. In order to ensure that the longitude zone width is fixed at all latitudes, the closer to the poles, the fewer longitude zones there are. By dividing the latitude according to the even coding method, the earth is divided into 60 equal parts, and 60 latitude zones are obtained. The width of each latitude zone is 6.00°. By dividing the latitude according to the odd coding method, the earth is divided into 59 equal parts, and 59 latitude zones are obtained. The width of each latitude zone is about 6.10°, which is slightly larger than the width of the latitude zone divided according to the even coding method. According to the S-mode reply transmitting equipment, the difference between the old code and the old code latitude zone is sent in turn, and the specific position of the aircraft can be accurately obtained, thus solving the problem of not being able to accurately determine the position of the transmitter after ignoring the high-order bit. Therefore, by defining and encoding each bit according to the ME in the air speed information, the flight information of the current aircraft can be obtained according to the code. Figure 6 Shown is a flow chart of the ME field regarding airspeed information.

[0056] Reference Figure 7 As shown, the program is first initialized, and then the ME field data used to represent the heading and speed of the transmitter device is sent to the single-chip microcomputer through the serial port. After the single-chip microcomputer receives the data sent by the serial port, it is necessary to compare the first bit of data received with the frame header FF. If they are different, wait for the serial port to resend the data. If they are the same, continue to judge the second bit of data. If the second bit of data does not represent the air position, it is calculated using the air speed algorithm. If it represents the air position, the corresponding data is calculated according to the CPR algorithm and placed in the 49-104 bits of the fixed array. Then, a pulse sequence is generated according to the fixed array and sent out through the control switch.

[0057] Among them, the CPR algorithm is:

[0058] The first step is to calculate the latitude Zone width Dlat:

[0059]

[0060] In the above formula, NZ is the number of latitude zones between the equator and the North Pole or the South Pole, NZ=15.

[0061] The second step is to calculate the latitude zone number YZ according to the latitude zone width Dlat:

[0062]

[0063] In the above formula, lat is the latitude of the ADS-B transmitter, in degrees, and NB is the code length, which is 17 here. floor(x) means rounding x to the maximum integer value less than or equal to x, and MOD(x,y) is the modulo function, which is defined as:

[0064]

[0065] Since the CPR latitude code YZ is rounded when it is obtained, the obtained coordinates are no longer equal to the actual input left side, so they need to be restored.

[0066] The fourth step is to calculate the number of longitude Zones NL corresponding to the latitude lat:

[0067]

[0068] The fifth step is to calculate the longitude zone length Dlon according to the obtained longitude zone number NL:

[0069]

[0070] At this point, the CPR algorithm encoding process has been completed. In CPR encoding, odd-even encoding does not mean using different algorithms for encoding, but that the data collection time and latitude zone width Dlat are different. The GNSS position update frequency is generally higher than 0.2 seconds, and each update meets the 0.2-second update frequency requirement. An even 0.2-second UTC time point is defined as: after the integer part of the starting time is an accurate even number of UTC seconds, the decimal part appears in an even multiple of 0.2 seconds; similarly, an odd 0.2-second UTC time point is defined as: after the integer part of the starting time is an accurate even number of UTC seconds, the decimal part appears in an odd multiple of 0.2 seconds. For example: an even 0.2-second time point refers to: 8.0 seconds, 8.4 seconds, 8.8 seconds, etc.; an odd 0.2-second time point refers to: 8.2 seconds, 8.6 seconds, 9.0 seconds, etc.

[0071] Although the Air Position Message Register may be updated at a frequency higher than 5 times per second, the CPR field will alternate between "0" and "1" only when the data loaded into the register is applicable at an odd or even 0.2 second UTC time point.

[0072] In this embodiment, the data about the aircraft information on the PC is sent to the STM32F756 microcontroller through the serial port. Then the corresponding aircraft message can be received on the serial port debugging assistant. At the same time, the pulse signal modulation waveform of the corresponding message can be seen on the oscilloscope.

[0073] First, the ADS-B air position information is tested. In this embodiment, a set of correct ADS-B data provided in the "Research and Implementation of Secondary Radar S-mode Signal Generation Technology" can be used for verification. The corresponding aircraft information contained in this set of data is a position point with a latitude of 4°, a longitude of 60°, and an altitude of 38,000ft for testing. In the serial port debugging assistant, a string of data [FF 0B 04 3C 94 70] should be entered. Through the serial port debugging assistant, the aircraft message information corresponding to the above data sent back by the single-chip microcomputer can be obtained.

[0074] According to the relevant algorithm rules, multiple manual calculations obtained the same results as the above message information, proving that the program-related algorithm is correct and can obtain the correct aircraft message information. The received information is displayed on the serial port debugging assistant, which are the parity codes of the corresponding input aircraft-related data. Eventually, the parity codes will be sent in turn to display the aircraft's air position information. When the serial port debugging assistant receives the data, the pulse signal modulation waveform of the corresponding data will also be displayed on the oscilloscope.

[0075] By analyzing the pulse signal modulation waveform on the oscilloscope, it can be determined that the waveform meets the requirements of the ADS-B message pulse shape. At the same time, the data expressed by the pulse is consistent with the aircraft message information received on the serial port debugging assistant.

[0076] Next, the ADS-B air speed information is tested. The aircraft is heading 37° west by north, with a speed of 1000 miles per hour (i.e., west vector speed of 800 miles per hour, north vector speed of 600 miles per hour), vertical heading upward, and vertical speed of 6400 feet per minute. In the serial port debugging assistant, you should enter the string of data [FF 1301 03 20 00 02 58 00 19 00]. Through the serial port debugging assistant, you can get the aircraft message information corresponding to the above data sent back by the single-chip microcomputer STM32F4 and the pulse waveform displayed on the oscilloscope. You can get accurate aircraft flight data.

[0077] The present invention discloses the following technical effects:

[0078] The present invention can use the ADS-B system and method as a virtual radar to provide control functions, and combine the S-mode secondary radar with the ADS-B technology to enable the aircraft to continuously broadcast its own address code, altitude, longitude and latitude and other information during flight, which is convenient for ground tracking and supervision, and has a low application cost. It can cover a larger area of ​​aviation transportation-related industries, which helps to further improve the safety rate of aircraft and improve the safety performance of the traffic control system and method.

[0079] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can still modify the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or perform equivalent replacements on some of the technical features thereof; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. They should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A system for generating an ADS-B signal, characterized in that: include: Signal generating unit, signal detecting unit, signal sending unit, pressure supply unit; The signal generating unit is used to obtain signal information; The signal generating unit includes a central control module, a voltage conversion module, a radio frequency switch module, and a signal source module; The voltage conversion module is used to convert the voltage provided by the pressure supply unit into the working voltage of the central control module; The signal source module is used to generate a 1090MHz high-frequency signal source; the signal source module adopts a secondary radar high-frequency signal generator; The central control module is used to output RF switch control instructions; the working voltage of the central control module is 3.3V; The RF switch module is used to perform a signal on-off operation according to the RF switch control instruction to obtain the signal information; The signal detection unit is used to detect the signal information and obtain the ADS-B reply signal; The signal sending unit is used to output the ADS-B reply signal; The voltage supply unit is used to provide working voltage to the signal generating unit and the signal detecting unit; The system uses a secondary radar high-frequency signal generator to generate a 1090MHz high-frequency signal source, and generates an S-mode output response signal through a hardware control circuit, while displaying a pulse of a certain width under the cooperation of a power supply circuit, an external clock and a software control program; Send the ADS-B transmitter location-related data through the serial port. After the single-chip microcomputer receives the data sent by the serial port, it needs to compare the first bit of data received with the frame header FF. If they are different, it means that the data sent is wrong and no subsequent operation is required. The role of the frame header is to prevent redundant data from interfering with the information. If they are the same, the second bit of data received will continue to be judged. When the second bit of data received is 19, it means that the information sent is ADS-B air speed information. The received data is calculated and a pulse sequence is generated according to the requirements of the air speed information. After that, the pulse sequence just generated is transmitted through the control switch. When the second bit of data received is 0, 9~18, 20~22, it means that the information sent is ADS-B air position information. The received data is calculated and a pulse sequence is generated according to the requirements of the air position information. After that, the pulse sequence just generated is transmitted through the control switch. The data sent to the PC through the serial port can be observed through the serial port debugging assistant to verify whether the algorithm in the program is correct.

2. The ADS-B signal generating system according to claim 1, characterized in that: The signal detection unit adopts a radio frequency logarithmic detector.

3. The ADS-B signal generating system according to claim 2, characterized in that: The voltage supply unit includes a first voltage source, a second voltage source, and a third voltage source; The first voltage source is used to provide an operating voltage to the voltage conversion module; The second voltage source is used to provide a working voltage to the RF switch module; The third voltage source is used to provide an operating voltage to the radio frequency logarithmic detector.

4. The ADS-B signal generating system according to claim 3, characterized in that: The first voltage source and the second voltage source are both 5V voltage sources; the third voltage source is a 7V voltage source.

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