An aircraft and emergency navigation and communication system based on Beidou short message

Abstract

The present invention discloses an aircraft and an emergency navigation and communication system based on Beidou short messages, wherein the aircraft comprises a front electronic cabin and a rear passenger cabin; the front electronic cabin comprises an airborne interface device, an inertial measurement unit, a flight management system, an electronic flight bag, a multi-mode receiver and a communication management unit / air traffic service unit; the rear passenger cabin comprises a positioning module; the positioning module adopts a positioning mode automatic selection method based on multi-constellation and multi-frequency point signals to determine the final position of the aircraft; the flight management system formulates an optimal flight plan according to a first positioning parameter or a second positioning parameter. The present invention upgrades the positioning module, adopts a positioning mode automatic selection method based on multi-constellation and multi-frequency point signals to determine the final position of the aircraft, realizes multi-frequency point accurate positioning of the second positioning parameter, and also provides a solution for formulating the optimal flight plan and realizing automatic control of the flight mission under special circumstances.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation navigation and communication, and in particular to an aircraft and emergency navigation and communication system based on Beidou short messages. Background Art

[0002] Beidou short message communication refers to the two-way information transmission between satellite positioning terminals and Beidou satellites or Beidou ground monitoring centers directly through satellite signals. It has three basic functions: position reporting, emergency search and rescue, and message communication. It is a special service of Beidou system's independent innovation and communication and navigation integration innovation. Beidou-3 system short message communication services include global short message communication (GSMC) service and regional short message communication (RSMC) service. Among them, the GSMC service meets the two-way communication needs of global users with a maximum single message length of 40 Chinese characters through 14 medium earth orbit (MEO) satellites and Beidou Ka inter-satellite links; RSMC service provides communication services with a maximum single message length of 1,000 Chinese characters and an average delay of less than 2 seconds through the two-way data transmission capabilities of 3 geostationary orbit (GEO) satellites to users on the surface of the earth in China and surrounding areas and in the near-earth area extending to an altitude of 1,000 kilometers in the air. Beidou short message service can help ground monitoring centers monitor and track aircraft flight status and other information, and its role in general aviation aircraft monitoring and tracking is becoming increasingly significant. However, its application value in aircraft emergency navigation and communication has yet to be explored.

[0003] The aircraft emergency navigation and communication system is designed to transmit the aircraft's monitoring and tracking information to the ground monitoring center in the event of communication interruption or natural disasters, and to temporarily provide navigation position information to the aircraft's front electronic compartment equipment, so as to ensure that the aircraft can safely arrive at the designated location and protect the safety of the aircraft and people's lives and property. At present, the multi-mode receiver (MMR) and inertial measurement unit (IMU) in the aircraft's front electronic compartment are the main navigation sources in the cockpit. The communication management unit / air traffic service unit (CMU / ATSU) obtains aircraft monitoring, operation command, aircraft important component status monitoring and ground business support instructions through the satellite / very high frequency (VHF) communication unit, and realizes one-way transmission of air traffic control (ATC) instructions, aviation operation control (AOC) instructions, route management control (AAC) instructions, and satellite communication (SATCOM) instructions with the airborne interface device (AID), and realizes one-way transmission of ATC instructions, AOC instructions and AAC instructions with the flight management system (FMS). The above equipment and communication methods can only provide navigation and communication services for aircraft during normal operation, and cannot provide emergency navigation and communication services for aircraft in special operating conditions, especially when MMR and IMU cannot work normally. In addition, although the Beidou position tracking terminal with Beidou short message communication function can continuously transmit aircraft position, speed, time and other parameters and large data with the ground monitoring center, the Beidou public service signal received by the positioning module in the terminal is still relatively single and cannot provide multi-frequency positioning services. Therefore, it is urgent to upgrade the position tracking terminal with Beidou-3 short message communication function and improve the airborne emergency navigation and communication system based on Beidou short messages. Summary of the invention

[0004] The purpose of the present invention is to provide an aircraft and emergency navigation communication system based on Beidou short messages, so as to realize multi-constellation and multi-frequency positioning to obtain the final positioning position of the aircraft and realize emergency navigation under special circumstances.

[0005] To achieve the above object, the present invention provides an aircraft based on Beidou short message, the aircraft comprising:

[0006] the forward electronics compartment and the rear passenger compartment;

[0007] The front electronic compartment includes: airborne interface equipment, inertial measurement unit, flight management system, electronic flight bag, multi-mode receiver and communication management unit / air traffic service unit;

[0008] The inertial measurement unit is connected to the airborne interface device and the flight management system respectively, the flight management system is connected to the multi-mode receiver and the communication management unit / air traffic service unit respectively, and the communication management unit / air traffic service unit, the multi-mode receiver and the electronic flight bag are all connected to the airborne interface device;

[0009] The rear cabin includes: a Beidou position tracking terminal and a GNSS antenna; the Beidou position tracking terminal includes a positioning module and a communication module; the positioning module is connected to the airborne interface device and the GNSS antenna respectively; the communication module is connected to the positioning module and the GNSS antenna respectively;

[0010] The GNSS antenna is used to receive multi-constellation and multi-frequency signals;

[0011] The positioning module is used to receive multi-constellation multi-frequency signals, determine the final position of the aircraft based on the multi-constellation multi-frequency signals using an automatic positioning mode selection method, and send second positioning parameters to the airborne interface device for storage; the second positioning parameters include: the final positioning position, time and speed of the aircraft.

[0012] an inertial measurement unit, for measuring IMU attitude data of the aircraft and transmitting the IMU attitude data to the flight management system and the onboard interface device;

[0013] a multi-mode receiver for calculating MMR navigation data of the aircraft and transmitting the MMR navigation data to the flight management system and the onboard interface device;

[0014] The onboard interface device is also used to store the first positioning parameters; the first positioning parameters include IMU attitude data and MMR navigation data;

[0015] When the situation is normal, the onboard interface device sends the first positioning parameter to the electronic flight bag for display; the flight management system formulates an optimal flight plan according to the first positioning parameter and realizes automatic control of the flight mission;

[0016] When there is a special situation, the airborne interface device sends the second positioning parameter to the electronic flight bag for display; the airborne interface device sends the second positioning parameter to the flight management system through the communication management unit / air traffic service unit, so that the flight management system formulates the best flight plan according to the second positioning parameter and realizes automatic control of the flight mission; the special situation is when the multi-mode receiver and / or the inertial measurement unit cannot work;

[0017] The communication module is used to receive the second positioning parameter sent by the positioning module, and forward it to the GNSS antenna in the form of a short message, so that the GNSS antenna sends it to the ground monitoring center through the Beidou-3 satellite.

[0018] Optionally, the communication management unit / air traffic service unit is used to generate ACARS+ instructions, and send the ACARS+ instructions to the ground monitoring center via the airborne interface device, the communication module, the GNSS antenna and the Beidou-3 satellite in sequence; when the ground monitoring center receives the ACARS+ instructions, the ACARS+ data is sent to the airborne interface device via the Beidou-3 satellite, the GNSS antenna and the communication module in sequence for storage; the ACARS+ instructions are instructions for the crew to request the ground to upload large data; the ACARS+ data are data larger than a set data volume.

[0019] Optionally, the front electronic compartment further includes: a satellite / VHF communication unit connected to a ground monitoring center and a communication management unit / air traffic service unit, respectively;

[0020] The satellite / VHF communication unit is used to receive downlink instructions and uplink instructions; the downlink instructions are generated by the communication management unit / air traffic service unit; the downlink instructions include: air traffic control ATC request instructions, short-distance downlink data instructions and satellite communication SATCOM request instructions; the ATC request instruction is an instruction for the crew to request clearance from the ground; the short-distance downlink data instruction is an instruction for the short-distance crew to issue downlink data to the ground; the SATCOM request instruction is an instruction for the long-distance crew to request data from the ground;

[0021] The upload instruction is generated by the ground monitoring center; the upload instruction includes: air traffic control ATC approval instruction, short-distance upload data instruction and satellite communication SATCOM broadcast instruction; the ATC approval instruction is an instruction for the ground to approve the release to the crew; the short-distance upload data instruction is an instruction for the ground to issue upload data to the crew at a short distance; the SATCOM broadcast instruction is a long-distance ground to broadcast data to the crew;

[0022] The satellite / very high frequency communication unit sends the downlink instruction to the ground monitoring center, and sends the uplink instruction to the communication management unit / air traffic service unit; the communication management unit / air traffic service unit sends the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction to the flight management system, so that the flight management system formulates the best flight plan and realizes automatic control of the flight mission according to the first positioning parameter, the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction; or formulates the best flight plan and realizes automatic control of the flight mission according to the second positioning parameter, the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction; or formulates the best flight plan and realizes automatic control of the flight mission according to the third positioning parameter, the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction;

[0023] The communication management unit / air traffic service unit sends the upload instruction and the download instruction to the airborne interface device for storage.

[0024] Optionally, the method of automatically selecting a positioning mode to determine the final position of the aircraft specifically comprises the following steps:

[0025] Step S1: First, use the single-frequency signal in each constellation to perform standard single-point positioning to obtain a standard single-point positioning result;

[0026] Step S2: judging whether the area where the aircraft is located is within the precise point positioning service area according to the standard point positioning result; if the aircraft is within the precise point positioning service area, judging whether there is a precise point positioning signal available; if there is a precise point positioning signal available, selecting the precise point positioning mode for positioning, and outputting the precise point positioning result as the final positioning position; if there is no precise point positioning signal available, executing "step S3"; if the aircraft is outside the precise point positioning service area, executing "step S3";

[0027] Step S3: Determine whether the area where the aircraft is located is within the satellite-based augmentation service area; if the aircraft is within the satellite-based augmentation service area, determine whether there is a satellite-based augmentation service signal available; if there is a satellite-based augmentation signal available, select the satellite-based augmentation positioning mode for positioning, and output the satellite-based augmentation positioning result as the final positioning position; if there is no satellite-based augmentation signal available, execute "Step S4"; if the aircraft is outside the satellite-based augmentation service area, execute "Step S4";

[0028] Step S4: Determine whether a dual-frequency signal is available. If a dual-frequency signal is available, select the dual-frequency ionosphere-free positioning mode for positioning, and output the dual-frequency ionosphere-free positioning result as the final positioning position; if no dual-frequency signal is available, select the standard single-point positioning mode, and output the standard single-point positioning result as the final positioning position.

[0029] Optionally, the communication module includes an international search and rescue module, a global short message communication module, an Iridium communication module and a Beidou regional short message module, and the communication module adopts an automatic switching communication method for satellite communication, and the steps of the automatic switching communication method specifically include:

[0030] Step S5: Determine whether the current communication working module is the international search and rescue module; if the current communication working module is the international search and rescue module, close the regional short message communication module, the global short message communication module and the Iridium communication module, and continue to use only the international search and rescue module for satellite communication; if the current communication working module is not the international search and rescue module, execute step S6;

[0031] Step S6: judging whether the area where the aircraft is located is within the Beidou regional short message service area according to the final positioning position; if it is within the Beidou regional short message service area, executing step S7; if it is outside the Beidou regional short message service area, executing step S8;

[0032] Step S7: Determine whether the current communication working module is the Beidou regional short message communication module; if the current communication working module is the Beidou regional short message communication module, close the international search and rescue module, the global short message communication module and the Iridium communication module, and continue to use only the Beidou regional short message module for satellite communication; if the current communication working module is not the Beidou regional short message communication module, use the global short message communication module for satellite communication;

[0033] Step S8: Determine whether the current communication working module is the Iridium communication module; if the current communication working module is the Iridium communication module, close the international search and rescue module, the global short message communication module and the regional short message communication module, and continue to use only the Iridium communication module for satellite communication; if the current communication working module is not the Iridium communication module, use the global short message communication module for satellite communication.

[0034] Optionally, the communication module sends data to the BeiDou-3 satellite in a packet-by-packet synchronous forwarding manner.

[0035] Optionally, the data sub-packets obtained after packetization include: a session ID, a packetization identifier, a packetization quantity, a packetization ID, a packetization satellite PRN number, and packetization information.

[0036] The present invention also provides a Beidou short message emergency navigation and communication system, the system comprising the above-mentioned aircraft, a Beidou-3 satellite and a ground monitoring center;

[0037] The communication module of the aircraft synchronously forwards the second positioning parameters to the ground monitoring center through the Beidou-3 satellite sub-packets.

[0038] Optionally, each satellite in the BeiDou-3 satellite is equipped with a regional short message payload and antenna, a global short message payload and antenna, and an international search and rescue payload and antenna.

[0039] Optionally, the ground monitoring center includes: a command aircraft antenna, a command aircraft, a ground monitoring terminal and a VHF ground terminal; the command aircraft antenna is connected to the ground monitoring terminal through the command aircraft, and the VHF ground terminal is connected to the satellite / very high frequency communication unit.

[0040] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0041] The present invention discloses an aircraft and an emergency navigation and communication system based on Beidou short messages. The positioning module is upgraded, and a positioning mode automatic selection method is adopted based on multi-constellation and multi-frequency point signals to determine the final position of the aircraft, so that multi-frequency point positioning is realized to accurately obtain a second positioning parameter. At the same time, a solution for a flight management system to formulate an optimal flight plan and realize automatic control of flight missions under special circumstances is also provided, thereby overcoming the problem that the prior art solutions cannot provide multi-frequency positioning services and cannot provide emergency navigation and communication services for aircraft under special operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] 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.

[0043] Figure 1 This is a schematic diagram of a GNSS antenna receiving multiple constellations according to the present invention;

[0044] Figure 2 This is a flow chart of the automatic positioning mode selection method of the present invention;

[0045] Figure 3 It is a schematic diagram of the communication link connection between the front electronic cabin and the rear passenger cabin of the present invention;

[0046] Figure 4 This is a schematic diagram of the BeiDou-3 satellite payload composition after the present invention is installed;

[0047] Figure 5 This is a flow chart of the automatic communication switching method of the present invention;

[0048] Figure 6 This is a schematic diagram of the arrangement of the B2b signal message of the present invention;

[0049] Figure 7 This is a schematic diagram of a queue for synchronously forwarding packetized data by multiple satellites of the present invention;

[0050] Figure 8 This is a schematic diagram of the installation position of the GNSS antenna of the present invention;

[0051] Fig. 9 This is a schematic diagram of the airborne emergency navigation and communication system architecture of the present invention;

[0052] Explanation of symbols:

[0053] 1-Front electronic compartment, 2-Rear cabin, 3-Inertial measurement unit, 4-Flight management system, 5-Multi-mode receiver, 6-Satellite / VHF communication unit, 7-Communication management unit / Air traffic service unit, 8-Airborne interface equipment, 9-GNSS antenna, 10-Beidou position tracking terminal, 11-Electronic flight bag, 12-Ground monitoring center, 13-Command aircraft antenna, 14-Command aircraft, 15-Ground monitoring terminal, 16-VHF ground station, 17- Beidou-3 satellite, 18-Other equipment. DETAILED DESCRIPTION

[0054] 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.

[0055] The purpose of the present invention is to provide an aircraft and emergency navigation communication system based on Beidou short messages, so as to realize multi-constellation and multi-frequency positioning to obtain the final positioning position of the aircraft and realize emergency navigation under special circumstances.

[0056] 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.

[0057] The technical problems mainly solved by the solution disclosed in the present invention include:

[0058] 1. Upgrade of positioning module in Beidou location tracking terminal

[0059] The BeiDou-3 global satellite navigation system has completed global networking. In addition to being able to receive BeiDou B1I signals, the positioning module used for aircraft tracking should also have the ability to receive other constellation signals and BeiDou new system signals, as well as the ability to automatically select positioning modes. In view of the low accuracy and reliability of single-point positioning using only B1I signals, the present invention needs to upgrade the positioning module that can only use B1I signals for aircraft positioning, replace the high-performance board card to receive multi-frequency navigation positioning signals, and increase dual-frequency ionosphere-free positioning, satellite-based enhanced positioning and precision single-point positioning modes on the basis of standard single-point positioning; in view of the problem that adding service signals will occupy more terminal channels, high complexity in positioning mode selection and high difficulty in positioning algorithm design, the present invention establishes an automatic positioning mode selection method based on service areas and signal availability. The positioning module can use this method to automatically give priority to using higher-precision positioning modes in different service areas, thereby ensuring the high accuracy and high reliability of the upgraded BeiDou position tracking terminal 10.

[0060] 2. Established a communication mechanism between the front electronic cabin 1 and the rear passenger cabin 2 of the aircraft

[0061] The AID, electronic flight bag 11 (EFB) and communication management unit / air traffic service unit 7 (CMU / ATSU) and other equipment located in the front electronic cabin 1 (referred to as the front cabin) of the aircraft, as well as the Beidou position tracking terminal 10 and other equipment in the rear cabin 2 (referred to as the rear cabin), in addition to being able to use separate communication links to complete the transmission of front cabin data and rear cabin data respectively, should also have the ability of one-way communication and two-way communication between the front and rear cabins. In view of the problem that the aircraft's onboard communication system lacks a front and rear cabin communication mechanism, the present invention needs to establish a communication link between the front cabin and the rear cabin, which can not only meet the storage and post-evaluation requirements of aircraft identification numbers, positions, speeds and other parameters under normal operation, but also meet the requirements of using the stored position information in the front cabin as a navigation reference in an emergency, and can also assist the communication addressing and reporting system (ACARS) to accelerate the two-way transmission of the aircraft and the ground in-flight entertainment system database, navigation database and a large amount of voice and image data, ensure the high-speed and reliable transmission of aircraft data and front and rear cabin broadband, increase the source of aircraft navigation data, and improve the passenger experience.

[0062] 3. Communication module upgrade in Beidou location tracking terminal

[0063] The short message payload and search and rescue payload of BeiDou-3 satellite 17 have not yet reached the full constellation configuration state, and the satellite utilization rate has not been maximized. There is frequency overlap between BeiDou short message service and Iridium communication service, resulting in the BeiDou short message service having a lower priority than the Iridium communication service when the two interfere with each other. In view of the problem that the BeiDou-3 system fails to provide short message service and international search and rescue service for the entire constellation, the present invention proposes a scheme for adding payloads to BeiDou-3 satellite 17 and a scheme for adding communication modules to BeiDou location tracking terminal 10, which expands the service coverage, increases the number of onboard transponders and system capacity, and provides users with more optional communication methods; in view of the compatibility issues between BeiDou short message service and Iridium communication service and the communication mode selection problem after adding payloads, the present invention establishes a method for switching short message communication module, international search and rescue module and Iridium communication module in BeiDou location tracking terminal 10, and reduces the return link delay and frequency interference by switching communication modes.

[0064] 4. Data forwarding strategy of the communication module in the Beidou location tracking terminal

[0065] In order to meet the ACARS+ function of transmitting large data such as voice images and airborne navigation information, the communication module needs to frequently interact with the ground monitoring center 12 and the data length exceeds the capacity of a single short message. The data must be sub-packetized for transmission to complete the communication task of a large amount of data. In view of the problems of long sub-packet transmission time, large service response delay and low frequency of distress reports of a single Beidou satellite, the present invention proposes a communication data forwarding strategy of using multiple Beidou satellites to synchronously transmit different sub-packets, selects multiple user uplink satellites and downlink satellites according to the number of visible satellites and elevation angles, and designs data sub-packet parameters and return communication B2b signal message format.

[0066] 5. Airborne emergency navigation and communication system architecture

[0067] In view of the problem that the navigation and communication equipment in the front cabin of an aircraft may fail under special circumstances, the present invention provides a new architecture of an aircraft's onboard emergency navigation and communication system based on the Beidou short message communication service and the front and rear cabin communication links. This system architecture, while meeting the requirements of data and command transmission between various devices in the front cabin of the aircraft and short message communication in the rear cabin under normal circumstances, utilizes the front and rear cabin communication links to realize the transmission of large data and the emergency navigation and communication function under special operating conditions.

[0068] The following is a detailed discussion of each technical point:

[0069] like Fig. 9 As shown, the present invention provides an aircraft based on Beidou short message, and the aircraft includes: a front electronic cabin 1 and a rear passenger cabin 2.

[0070] The front electronic cabin 1 includes: an airborne interface device 8 (abbreviated as AID), an inertial measurement unit 3 (abbreviated as IMU), a flight management system 4 (abbreviated as FMS), an electronic flight bag 11 (abbreviated as EFB), a multi-mode receiver 5 (abbreviated as MMR) and a communication management unit / air traffic service unit 7 (abbreviated as CMU / ATSU); the inertial measurement unit 3 is connected to the airborne interface device 8 and the flight management system 4 respectively, the flight management system 4 is connected to the multi-mode receiver 5 and the communication management unit / air traffic service unit 7 respectively, and the communication management unit / air traffic service unit 7, the multi-mode receiver 5 and the electronic flight bag 11 are all connected to the airborne interface device 8; the rear cabin 2 includes: a Beidou position tracking terminal 10 and a GNSS antenna 9; the Beidou position tracking terminal 10 includes a positioning module and a communication module; the positioning module is connected to the airborne interface device 8 and the GNSS antenna 9 respectively; the communication module is connected to the positioning module and the GNSS antenna 9 respectively.

[0071] The GNSS antenna 9 is used to receive multi-constellation and multi-frequency signals; in this embodiment, the multi-constellation and multi-frequency signals include: Beidou B1 band, B2 band and B3 band, GPS L1 band, L2 band and L5 band, GLONASS L1 band and L2 band, and Galileo E1 band and E5 band.

[0072] The positioning module is used to receive multi-constellation multi-frequency signals, determine the final position of the aircraft based on the multi-constellation multi-frequency signals, and use the automatic positioning mode selection method to send the second positioning parameters to the airborne interface device 8 for storage; the second positioning parameters include: the final positioning position, time and speed of the aircraft.

[0073] The inertial measurement unit 3 is used to measure the IMU attitude data of the aircraft and transmit the IMU attitude data to the flight management system 4 and the airborne interface device 8; the IMU attitude data includes three-axis attitude angle, angular velocity and angular acceleration.

[0074] The multi-mode receiver 5 is used to calculate the MMR navigation data of the aircraft and transmit the MMR navigation data to the flight management system 4 and the airborne interface device 8; the MMR navigation data includes the position, speed and time of the aircraft; the multi-mode receiver 5 includes navigation equipment including an ILS receiver, an MLS receiver, a GNSS receiver, a data broadcast receiver, etc.

[0075] The onboard interface device 8 is also used to store first positioning parameters; the first positioning parameters include IMU attitude data and MMR navigation data;

[0076] When the situation is normal, the onboard interface device 8 sends the first positioning parameter to the electronic flight bag 11 for display; the flight management system 4 formulates the best flight plan according to the first positioning parameter and realizes automatic control of the flight mission.

[0077] When there is a special situation, the onboard interface device 8 sends the second positioning parameter to the electronic flight bag 11 for display; the onboard interface device 8 sends the second positioning parameter to the flight management system 4 through the communication management unit / air traffic service unit 7, so that the flight management system 4 formulates the best flight plan according to the second positioning parameter and realizes automatic control of the flight mission; in this embodiment, the special situation is when the multi-mode receiver 5 and / or the inertial measurement unit 3 cannot work, that is, the front cockpit navigation equipment is damaged by human beings or the equipment fails, and cannot provide the required navigation information to the flight management system 4 normally.

[0078] The communication module is used to receive the second positioning parameter sent by the positioning module, and forward the second positioning parameter to the GNSS antenna 9 in the form of a fixed period and short message, so that the GNSS antenna 9 sends it to the ground monitoring center 12 through the Beidou-3 satellite 17.

[0079] In the above embodiment, the GNSS antenna 9 can also be used to receive a third positioning parameter; the third positioning parameter is the initial position, time and speed of the aircraft, and the third positioning parameter is sent to the airborne interface device 8 in sequence through the communication module or the positioning module; in special circumstances, the airborne interface device 8 can also send the third positioning parameter to the electronic flight bag 11 for display; the airborne interface device 8 sends the third positioning parameter to the flight management system 4 through the communication management unit / air traffic service unit 7, so that the flight management system 4 can formulate the best flight plan according to the third positioning parameter and realize automatic control of the flight mission. The communication module receives the third positioning parameter sent by the positioning module or the GNSS antenna 9, and forwards the third positioning parameter to the GNSS antenna 9 in the form of a fixed period and short message, so that the GNSS antenna 9 sends it to the ground monitoring center 12 through the Beidou-3 satellite 17.

[0080] Under normal operation of the present invention, the MMR and IMU in the front electronic cabin 1 are used as the main navigation sources of the cockpit, and the first positioning parameters are sent to the electronic flight bag 11 for display; in special circumstances, the GNSS antenna 9 or the positioning module in the rear cabin 2 is used as the main navigation source of the cockpit, and the second positioning parameter or the third positioning parameter is sent to the electronic flight bag 11 for display.

[0081] As an optional implementation, the communication management unit / air traffic service unit 7CMU / ATSU of the present invention is used to generate ACARS+ instructions, and send the ACARS+ instructions to the ground monitoring center 12 through the airborne interface device 8, the communication module, the GNSS antenna 9 and the Beidou-3 satellite 17 in sequence; When the ground monitoring center 12 receives the ACARS+ instruction, the ACARS+ data is sent to the airborne interface device 8 through the Beidou-3 satellite 17, the GNSS antenna 9 and the communication module in sequence for storage; The ACARS+ instruction is a large data upload instruction requested by the crew to the ground; ACARS+ data is data greater than the set data volume. Data greater than the set data volume can be a large amount of text, pictures, images, voice and other content, and can also be large data such as navigation databases, obstacle data and entertainment system data.

[0082] As an optional embodiment, the front electronic compartment 1 of the present invention also includes: a satellite / very high frequency communication unit 6 (VHF for short), which is connected to the ground monitoring center 12 and the communication management unit / air traffic service unit 7 respectively; the satellite / very high frequency communication unit 6 is used to receive downlink instructions and upload instructions; the downlink instructions are generated by the communication management unit / air traffic service unit 7; the downlink instructions include: air traffic control ATC request instructions, short-range downlink data instructions and satellite communication SATCOM request instructions; the ATC request instruction is an instruction for the crew to request release from the ground; the short-range downlink data instruction is an instruction for the short-range crew to release downlink data to the ground; the SATCOM request instruction is an instruction for the long-range crew to request data from the ground; the upload instruction is generated by the ground monitoring center 12; the upload instruction includes: air traffic control ATC approval instruction, short-range upload data instruction and satellite communication SATCOM broadcast instruction; the ATC approval instruction is an instruction for the ground to approve release to the crew; the short-range upload data instruction is an instruction for the short-range ground to release upload data to the crew; the SATCOM broadcast instruction is an instruction for the long-range ground to broadcast data to the crew. Broadcast data includes data used to update onboard audio and video content and provide voice communication services.

[0083] The satellite / very high frequency communication unit 6 sends the downlink instruction to the ground monitoring center 12, and sends the uplink instruction to the communication management unit / air traffic service unit 7; the communication management unit / air traffic service unit 7 sends the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction to the flight management system 4, so that the flight management system 4 formulates the best flight plan and realizes the automatic control of the flight mission according to the first positioning parameter, the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction; or formulates the best flight plan and realizes the automatic control of the flight mission according to the second positioning parameter, the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction; or formulates the best flight plan and realizes the automatic control of the flight mission according to the third positioning parameter, the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction. The FMS manages the flight plan and navigation notice according to the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction.

[0084] The communication management unit / air traffic service unit 7 sends the uploading instruction and the downloading instruction to the airborne interface device 8 for storage. The communication management unit / air traffic service unit 7 is also used to receive ACARS+ data transmitted by the AID.

[0085] In this embodiment, the satellite / very high frequency (VHF) communication unit includes a satellite communication (SATCOM) antenna, a SATCOM communication terminal, a very high frequency (VHF) antenna, and a VHF communication radio. The SATCOM communication terminal is connected to the VHF ground station 16 via the SATCOM antenna and the SATCOM satellite, the SATCOM communication terminal is connected to the CMU / ATSU, and the VHF communication radio is connected to the VHF ground station 16 via the VHF antenna.

[0086] The SATCOM communication terminal can send data access requests to the SATCOM satellite through the SATCOM antenna according to the SATCOM request instructions sent by the CMU / ATSU, and will receive the SATCOM broadcast instructions sent by the SATCOM satellite and transmit them back to the CMU / ATSU through the SATCOM antenna and the SATCOM communication terminal.

[0087] The very high frequency (VHF) antenna and the VHF communication radio station transmit air traffic control ATC request instructions, short-range downlink data instructions, air traffic control ATC approval instructions and short-range uplink data instructions to each other with the VHF ground station 16 .

[0088] In this embodiment, the electronic flight bag 11 (EFB), a display control system that assists the pilot in flying, can send data retrieval control instructions to the AID, receive in real time IMU attitude data, MMR navigation data, short-range downlink data instructions, ATC instructions, first positioning parameters, second positioning parameters, third positioning parameters, ARCARS+ data and other navigation data forwarded by the AID, and display the above data on a matching display for the pilot to read and refer to.

[0089] In this embodiment, the Beidou position tracking terminal 10 can use the added regional short message communication module, global short message communication module, international search and rescue module, and Iridium communication module to realize Beidou regional short message communication, global short message communication, international search and rescue communication, and Iridium communication; it can use the upgraded high-performance receiver board and full-frequency satellite navigation antenna to realize standard single-point positioning, dual-frequency ionosphere-free positioning, satellite-based enhanced positioning, and precise single-point positioning; it can use the rear cabin 2 unidirectional communication link to send aircraft parameters including position to AID storage, and use the rear cabin 2 bidirectional communication link to send ACARS+ data to AID storage and forwarding; it can use the short message communication module to continuously send aircraft parameters to the ground monitoring center 12, and exchange ACARS+ data with the ground monitoring center 12.

[0090] like Fig. 9 As shown, other equipment 18 includes a display unit and an onboard printer.

[0091] Under normal operation, the MMR and IMU in the front electronic compartment 1 of the aircraft are the main navigation sources of the cockpit. The navigation data output by the MMR and the attitude data output by the IMU are transmitted one-way with the AID and FMS. The CMU / ATSU obtains information such as aircraft monitoring, operation command, status monitoring of important aircraft components (i.e., wings, fuselage, tail, landing gear, power unit) and ground business support through the satellite / VHF communication unit, and transmits short-distance uplink data instructions, short-distance downlink data instructions, ATC request instructions, ATC approval instructions, SATCOM request instructions, SATCOM broadcast instructions and ACARS+ instructions to the AID one-way, and transmits short-distance uplink data instructions, short-distance downlink data instructions, ATC request instructions and ATC approval instructions to the FMS one-way. The EFB, as a navigation display control unit, provides reference for the pilot and transmits two-way with the AID. In addition to transmitting data two-way with the CMU / ATSU and EFB, the AID (such as FOMAX or Teledyne) is also responsible for receiving and storing IMU, MMR and Beidou position tracking terminal 10 The Beidou position tracking terminal 10 in the rear cabin 2 of the aircraft, in addition to continuously sending the aircraft identification number, position, speed, time and other parameters in the form of short messages to the ground monitoring center 12 to prevent the aircraft from losing contact, also transmits the aircraft's second positioning parameter, third positioning parameter and bidirectional ACARS+ data through the rear cabin 2 communication link with the front electronic cabin 1AID. In particular, the aircraft parameters (especially the position parameters) transmitted from the rear cabin 2 to the front electronic cabin 1 are not displayed to the crew, nor can they be used as a basis for air traffic control personnel to make air traffic control decisions.

[0092] In special operating conditions (i.e., when the navigation equipment in the front cockpit is damaged or the equipment fails), mainly when the MMR and IMU cannot provide normal navigation and positioning services, the working mode of other equipment such as the AID in the front electronic compartment 1 is the same as that in normal operation, but the second positioning parameter or the third positioning parameter transmitted to the AID by the rear cabin 2 through the communication link can be transmitted to the FMS, and it can be temporarily used as a navigation source to realize the Beidou-3 emergency navigation function. In addition, although the current domestically produced MMR equipment is subject to the constraints of international industrial standards and the airworthiness cycle, it is difficult to replace the existing foreign-produced airborne MMR equipment in the short term, but the domestically produced MMR can be installed in the front electronic compartment 1 of the aircraft as a backup / emergency navigation equipment, cross-linked with the AID and displaying the results on the EFB, providing reference for pilots while accumulating flight data, continuously iterating and improving the research and development level of the domestically produced MMR, and can also be used as a backup navigation equipment, and temporarily used as a navigation source to realize the Beidou-3 emergency navigation function under special circumstances.

[0093] A BeiDou position tracking terminal 10 is installed in the rear cabin 2 of the aircraft and Figure 8 The antenna installation area shown is installed with a GNSS antenna 9 (taking the Airbus A380 aircraft as an example). To prevent the poor quality of the antenna receiving signal due to the tilt of the aircraft, one or more satellite communication antennas (i.e., GNSS antennas 9) can be installed in the installation area between the rear cabin 2 and the wing, and connected to the Beidou position terminal in the rear cabin 2. If only one antenna is installed, the terminal is directly connected to the antenna through a radio frequency cable; if multiple antennas are installed, an additional antenna control system is required to adjust, control, and select the communication antenna. The present invention ensures that short message communication will not be interrupted by installing a satellite communication antenna.

[0094] The present invention uses the one-way communication of the rear cabin 2 to realize the emergency navigation of the aircraft: the parameters such as the position, speed and time output by the Beidou position tracking terminal 10 are not only forwarded to the ground monitoring center 12 through the medium earth orbit (MEO) satellite / geostationary orbit (GEO) satellite in the form of short messages, but also transmitted to the airborne interface device 8 through the communication link of the rear cabin 2 for storage and standby. Under normal operation, no data transmission is performed with the CMU / ATSU and EFB and other equipment, and it is used as the emergency navigation of the aircraft only under special operation conditions. Special conditions refer to the situation that the navigation equipment in the front cockpit is damaged by human beings or the equipment fails, and it cannot normally provide the required navigation information to the flight management system 4.

[0095] The Beidou position tracking terminal 10 with Beidou-3 short message communication function is carried on civil aviation passenger aircraft and other aircraft, and the positioning module and communication module of the Beidou position tracking terminal 10 are upgraded. The positioning mode, communication mode, short message forwarding strategy, message format, front and rear cabin communication mechanism and navigation and communication system architecture are optimized to improve the navigation positioning accuracy, data transmission frequency and communication business scope, refine the aircraft's onboard communication mechanism and emergency navigation and communication architecture, and ensure that the aircraft can still provide reliable monitoring and tracking and emergency navigation and communication services under special conditions such as communication interruption, natural disasters and emergencies, so as to protect the safety of aircraft and people's lives and property.

[0096] GNSS antenna receives multi-constellation and multi-frequency signals: The standard "Beidou Satellite Navigation System (BDS) Airborne Equipment Used Only for Aircraft Tracking" stipulates that the BDS airborne equipment positioning unit that only realizes the aircraft tracking function should be able to receive the B1I Beidou public service signal, and provide the aircraft identification number, location information (latitude, longitude and altitude), ground speed information based on the BDCS coordinate system, and time information based on Coordinated Universal Time (UTC). The Beidou-3 global satellite navigation system has completed global networking. In addition to being able to receive Beidou B1I signals, the positioning module used for aircraft tracking should also have the ability to receive other constellation signals and Beidou new system signals, as well as automatically select the positioning mode. Therefore. In order to solve the problem of low accuracy and reliability of single-point positioning using only B1I signals, the present invention needs to upgrade the positioning module that can only use B1I signals for aircraft positioning, and replace the high-performance board card to use multi-frequency navigation and positioning signals to achieve positioning.

[0097] The present invention upgrades the positioning module in the Beidou position tracking terminal 10 to achieve multi-frequency and multi-constellation positioning. The terminal is replaced with a high-performance receiver board so that the terminal positioning module can receive and process multiple navigation constellation multi-frequency point signals sent by the GNSS antenna 9 in real time, including but not limited to Figure 1 The constellations and signals given. Taking the navigation signals of the three frequency bands B1, B2 and B3 in the Beidou satellite navigation system BDS as an example, the B1I, B2I and B3I frequency signals can be used for standard single-point positioning and dual-frequency ionosphere-free positioning, the B1C and B2a frequency signals can be used for satellite-based augmented positioning, and the B2b frequency signals can be used for precise single-point positioning. The signal frequencies and positioning modes of the navigation constellations of the GLONASS satellite navigation system, the US global positioning system GPS, and the European Galileo satellite positioning system Galileo are basically the same as those of Beidou, so they will not be discussed one by one here.

[0098] Automatic selection of positioning mode: on the basis of the standard single-point positioning mode, dual-frequency ionosphere-free positioning mode, satellite-based enhanced positioning mode and precise single-point positioning mode are added; in view of the problems that adding service signals will occupy more terminal channels, high complexity of positioning mode selection and great difficulty in positioning algorithm design, the present invention is based on the positioning module being able to receive and process multi-constellation and multi-frequency signals. Figure 2 The automatic positioning mode selection process is given, and an automatic positioning mode selection method is established according to the service area and signal availability to select a positioning mode with higher accuracy, so that the positioning module uses this method to automatically give priority to using a positioning mode with higher accuracy in different service areas, thereby ensuring the high accuracy and high reliability of the upgraded Beidou position tracking terminal 10.

[0099] like Figure 2As shown, assuming that there is at least one available frequency signal, the specific steps of the positioning mode automatic selection method are as follows:

[0100] Step S1: The positioning module first uses the single-frequency signal (such as B1I) in each constellation to perform standard single-point positioning to obtain a standard single-point positioning result.

[0101] Step S2: Determine whether the area where the aircraft is located is within the precise point positioning service area based on the standard point positioning result; if the aircraft is within the precise point positioning service area, determine whether there is a precise point positioning signal (such as B2b); if a precise point positioning signal is available, select the precise point positioning mode for positioning, and output the precise point positioning result as the final positioning position; if no precise point positioning signal is available, execute "Step S3"; if the aircraft is outside the precise point positioning service area, execute "Step S3".

[0102] Step S3: Determine whether the area where the aircraft is located is within the satellite-based augmentation service area; if the aircraft is within the satellite-based augmentation service area, determine whether there is a satellite-based augmentation service signal (such as B1C and B2a) available; if a satellite-based augmentation signal is available, select the satellite-based augmentation positioning mode for positioning, and output the satellite-based augmented positioning result as the final positioning position; if no satellite-based augmentation signal is available, execute "Step S4"; if the aircraft is outside the satellite-based augmentation service area, execute "Step S4".

[0103] Step S4: Determine whether a dual-frequency signal (such as B1I and B3I) is available. If a dual-frequency signal is available, select the dual-frequency ionosphere-free positioning mode for positioning, and output the dual-frequency ionosphere-free positioning result as the final positioning position; if no dual-frequency signal is available, select the standard single-point positioning mode, and output the standard single-point positioning result as the final positioning position.

[0104] Establishing a communication link between the front and rear cabins of the aircraft: the AID, electronic flight bag 11, and communication management unit / air traffic service unit 7 and other equipment located in the front electronic cabin 1 of the aircraft, as well as the Beidou position tracking terminal 10 and other equipment in the rear cabin 2, in addition to being able to use separate communication links to complete the transmission of the data of the front electronic cabin 1 and the rear cabin 2 respectively, should also have the ability of one-way communication and two-way communication in the rear cabin 2. In view of the problem that the aircraft's onboard communication system lacks a communication mechanism for the rear cabin 2, the present invention needs to establish a communication link between the front electronic cabin 1 and the rear cabin 2, which can not only meet the storage and post-evaluation requirements of parameters such as aircraft identification number, position and speed under normal operation, but also meet the requirements of the front electronic cabin 1 using the stored position information as a navigation reference in an emergency, and can also assist the communication addressing and reporting system (ACARS) to accelerate the two-way transmission of the aircraft and the ground in-flight entertainment system database, navigation database and a large amount of voice and image data, ensure the broadband, high-speed and reliable transmission of aircraft data and the rear cabin 2, increase the source of aircraft navigation data, and improve the passenger experience.

[0105] like Figure 3 As shown, the present invention has established both one-way communication transmission of aircraft parameters and two-way communication transmission of large business data; aircraft parameters include aircraft identification number, position, speed and time parameters, and large business data include a large amount of civil aviation user information, text, pictures, images and voice and other contents. Specifically, the present invention uses cables or optical fibers to establish a wired communication link between the airborne interface device 8 in the front electronic cabin 1 and the Beidou position tracking terminal 10 in the rear cabin 2 to achieve one-way data transmission of aircraft parameters; or uses space electromagnetic waves to establish a wireless communication link between the AID in the front electronic cabin 1 and the Beidou position tracking terminal 10 in the rear cabin 2 to achieve two-way data transmission of large business data.

[0106] Beidou position tracking terminal 10 ensures the normal operation of the short message communication function, that is, the output aircraft parameters are forwarded to the ground monitoring center 12 through MEO / GEO satellite in the form of short messages. Under the premise, Beidou position tracking terminal 10 also transmits the aircraft parameters to the AID in the front electronic cabin 1 through the communication link for storage and standby. Under normal circumstances, the aircraft parameters are not displayed to the crew, nor can they be used as a basis for air traffic control personnel to implement air traffic control decisions. Only in special circumstances (that is, when the navigation equipment of the front electronic cabin 1 is damaged or the equipment fails and cannot normally provide the required navigation information to the flight management system 4) are temporarily used as a navigation source and transmitted by AID to the electronic flight bag 11EFB to display the positioning results to the crew and transmit to CMU / ATSU as a basis for decision-making of the flight management system 4 (FMS).

[0107] Under the premise of ensuring basic communication and navigation functions, when the Beidou position tracking terminal 10 needs to transmit a large amount of text, pictures, images, voice and other content, or needs to support large data transmission such as navigation database, obstacle data and entertainment system data update, the communication management unit / air traffic service unit 7 of the front electronic cabin 1 can communicate two-way with the Beidou position tracking module of the rear cabin 2 through the airborne interface device 8, and then use the GNSS antenna 9 in the rear cabin 2 and the ground-to-air data link of the ground monitoring center 12 to complete the two-way transmission of the above information and data, thereby realizing the ACARS+ function.

[0108] Upgrade BeiDou-3 satellite payload and BeiDou position tracking terminal communication module

[0109] At present, BeiDou RSMC service is provided by L-band and S-band signals of three GEO satellites in the BeiDou-3 nominal space constellation, and can provide RSMC services to users on the earth's surface and near-earth areas extending 1,000 kilometers into the air in China and surrounding areas (the area between 75 degrees and 135 degrees east longitude and 10 degrees and 55 degrees north latitude). BeiDou GSMC service uses L-band and B2b signals of 14 MEO satellites to provide message communication services to users around the world. BeiDou international search and rescue (SAR) service is provided by six MEO satellites carrying search and rescue payloads evenly distributed in three orbital planes in the BeiDou-3 nominal space constellation. The return link is provided by 24 MEO satellites and three IGSO satellites in the BeiDou-3 nominal space constellation, and SAR services are provided to all users on the earth's surface and near-earth areas extending 50 kilometers into the air around the world using inter-satellite links. It can be seen that the utilization rate of the BeiDou-3 space constellation has not yet been maximized.

[0110] according to Figure 4The payload composition diagram of the BeiDou-3 satellite 17 shown in the figure is that for the BeiDou GEO satellite that only has the BeiDou regional short message payload and antenna installed, the BeiDou global short message payload and antenna, the international search and rescue payload and antenna, and the Iridium payload and antenna are installed; for the MEO satellite that only has the BeiDou global short message payload and antenna installed, the BeiDou regional short message payload and antenna, the international search and rescue payload and antenna, and the Iridium payload and antenna are installed; for the IGSO satellite and MEO satellite that only has the BeiDou international search and rescue payload and antenna installed, the BeiDou regional short message payload and antenna, the BeiDou global short message payload and antenna, and the Iridium payload and antenna are installed. Accordingly, in order to match and integrate the satellite payload and the terminal communication mode, for the BeiDou position tracking terminal 10 that only has the regional short message communication module installed, the global short message communication module, the international search and rescue module, and the Iridium communication module are installed; for the BeiDou position tracking terminal 10 that only has the global short message communication module installed, the regional short message communication module, the international search and rescue module, and the Iridium communication module are installed. When the communication frequency and bandwidth are the same, it may be preferred to use the same satellite communication antenna.

[0111] After the Beidou location tracking terminal 10 completes the installation of the communication module, follow Figure 5 The automatic switching communication method shown automatically switches the communication mode between Beidou regional short message, global short message, international search and rescue, and Iridium communication. Assuming that all communication modules are available, the steps of the automatic switching communication method are as follows:

[0112] Step S5: Determine whether the current communication working module is an international search and rescue module; if the current communication working module is an international search and rescue module, close the regional short message communication module, the global short message communication module and the Iridium communication module, and continue to use only the international search and rescue module for satellite communication; if the current communication working module is not an international search and rescue module, execute step S6.

[0113] Step S6: Determine whether the area where the aircraft is located is within the Beidou regional short message service area based on the final positioning position or the initial position; if it is within the Beidou regional short message service area, execute step S7; if it is outside the Beidou regional short message service area, execute step S8.

[0114] Step S7: Determine whether the current communication working module is the Beidou regional short message communication module; if the current communication working module is the Beidou regional short message communication module, turn off the international search and rescue module, the global short message communication module and the Iridium communication module, and continue to use only the Beidou regional short message module for satellite communication; if the current communication working module is not the Beidou regional short message communication module, use the global short message communication module for satellite communication.

[0115] Step S8: Determine whether the current communication working module is the Iridium communication module; if the current communication working module is the Iridium communication module, close the international search and rescue module, the global short message communication module and the regional short message communication module, and continue to use only the Iridium communication module for satellite communication; if the current communication working module is not the Iridium communication module, use the global short message communication module for satellite communication.

[0116] Multiple Beidou satellites synchronously forward communication data

[0117] The data to be transmitted is divided into multiple data sub-packets, each of which includes information such as "session ID", "sub-packet identification", "sub-packet quantity", "sub-packet ID", "sub-packet satellite PRN number" and "sub-packet information". Figure 7 As shown in the data queue diagram, satellites 1 to n first synchronously forward subpackets 1 to n, and then synchronously forward subpackets n+1 to 2n, until all subpackets are transmitted.

[0118] For Beidou regional short message communication service, 2 to 3 GEO satellites can be observed simultaneously in China and surrounding areas. In the way of evenly distributing the number of sub-packets, the regional short message communication module in the terminal allocates idle channels to transmit message data with different "sub-packet IDs" to all visible GEO satellites. If the number of sub-packets exceeds the number of visible GEO satellites, the remaining sub-packets are added to the queue to be transmitted of the corresponding GEO satellite, and the remaining sub-packets are transmitted in sequence after the previous sub-packet transmission is completed; if the sub-packet content contains a cancel transmission instruction, the short message communication module clears all channel queues to be transmitted, otherwise it will continue to transmit until all data is transmitted. Beidou regional short message return communication still uses even distribution and queue addition to select the GEO satellite corresponding to the "forwarding satellite PRN number" in the forward communication sub-packet to transmit all return data, and try to ensure that the forward communication and return communication use the same Beidou satellite to forward the regional short message data.

[0119] For BeiDou global short message communication service and international search and rescue service, multiple BeiDou IGSO satellites and MEO satellites can be observed at the same time in the world. The global short message communication module and international search and rescue module in the terminal first select visible satellites as data forwarding satellites according to the satellite elevation mask (optional 5°, 10°, 15° or higher), or select forwarding satellites according to the custom satellite elevation constraint (such as 30°), and then transmit all data by evenly distributing and joining the queue, and communicate with the domestic ground monitoring center 12 through the BeiDou Ka inter-satellite link. BeiDou global short message return communication transmits the packetized return data (the number of packets remains unchanged) to the MEO satellite corresponding to the "forwarding satellite PRN number" in the forward communication packet through the BeiDou Ka inter-satellite link, and then the MEO satellite completes the work of returning data to the global short message module; international search and rescue return communication returns data through the IGSO and MEO satellites corresponding to the "forwarding satellite PRN number" in the forward communication packet. If the BeiDou-3 satellite 17 payload and the BeiDou position tracking terminal 10 communication module are installed, BeiDou regional short messages, global short messages and international search and rescue services, and even forward and return communications of Iridium communication services can adopt the above strategy to select multiple satellites to synchronously forward communication data, thereby improving data transmission efficiency.

[0120] B2b signal message parameters and format design

[0121] The message format of short message single-packet data varies depending on the broadcast signal (regional short message user uplink signal uses L band, user downlink signal uses S band, global short message user uplink signal uses L band, user downlink signal uses B2b signal, international search and rescue user uplink signal uses UHF, payload downlink signal uses L band, reverse link / user downlink signal uses B2b signal), but the overall structure and content are similar. Here, taking B2b downlink signal as an example, the message parameters and format design results are given.

[0122] The user downlink signal of BeiDou Global Short Message Service and International Search and Rescue Service is broadcast by the B2b signal of BeiDou-3 IGSO and MEO satellites. The return communication data is carried by the navigation message in the B-CNAV3 format defined in the B2b interface file. The length of each message frame is 1000 symbol bits, the symbol rate is 1000sps, and the broadcast period is 1 second. The length of each message frame before error correction coding is 486 bits, including information type (6 bits), seconds in the week (20 bits), message data (436 bits), and cyclic redundancy check bits (24 bits). Information type, seconds in the week, and message data are all involved in the cyclic redundancy check calculation. After using 64-bit LDPC (162,81) coding, the length is 972 symbol bits.

[0123] Define the valid information type in the B-CNAV3 format message as 50 (can also be set to other values), which is specifically used for Beidou global short message return communication. The format is as follows: Figure 6 As shown. The 436-bit message data parameters and bit numbers are: session ID (19 bits, a unique identifier generated after the sender and receiver confirm the transmission), packet identification (1 bit, 0 indicates non-packetized transmission, 1 indicates packetized transmission), number of packets (2 bits, temporarily considering using up to 4 satellites to transmit message information), packet satellite PRN number (32 bits, 8 bits are allocated to each satellite to support multiple constellation satellites), packet information (382 bits, custom transmission includes short message information including Chinese characters, numbers, English and characters). The message parameters and formatting specifically used for Beidou regional short message return communication and international search and rescue service return communication can all refer to the above design ideas.

[0124] like Fig. 9 As shown, the present invention discloses an emergency navigation and communication system of Beidou short messages, the system includes the aircraft in Example 1, Beidou-3 satellite 17 and ground monitoring center 12; the communication module of the aircraft sub-packages and synchronously forwards the second positioning parameters to the ground monitoring center 12 through Beidou-3 satellite 17.

[0125] As an optional implementation, the ground monitoring center 12 of the present invention includes: a command aircraft antenna 13, a command aircraft 14, a ground monitoring terminal 15 and a VHF ground terminal; the command aircraft antenna 13 is connected to the ground monitoring terminal 15 through the command aircraft 14, and the VHF ground terminal is connected to the satellite / very high frequency communication unit 6. The VHF ground station 16 is used to send and receive ATC request instructions, ATC approval instructions, AOC and short-range upload data instructions to perform air traffic control on aircraft. The command aircraft antenna 13 receives the second positioning parameter, the third positioning parameter and the ACARS+ data transmission instruction in the form of a short message forwarded by the Beidou-3 satellite 17, and sends the above parameters to the ground monitoring terminal 15 through the command aircraft 14. The ground monitoring terminal 15 forwards the ACARS+ data in the form of a short message through the command aircraft 14, the command antenna and the Beidou-3 satellite 17 in turn, completing the large-scale data transmission between the aircraft and the ground monitoring center 12.

[0126] As an optional implementation, each satellite in the BeiDou-3 satellite 17 of the present invention is equipped with a regional short message payload and antenna, a global short message payload and antenna, and an international search and rescue payload and antenna. Figure 4 shown.

[0127] In summary, the present invention discloses the following technical points:

[0128] 1. Upgrade of positioning module in Beidou location tracking terminal

[0129] The receiver board in the Beidou position tracking terminal 10 of the present invention is used to carry the program of the positioning module, and the positioning module that can only process Beidou satellite signals is upgraded to a positioning module that can simultaneously capture and track all navigation constellations; at the same time, the satellite navigation antenna that only supports L1 frequency band signals is replaced with a full-frequency satellite navigation antenna (i.e., GNSS antenna 9) that can simultaneously work in L1, L2 and L5 frequency bands; the upgraded positioning module can simultaneously receive and process Beidou (B1, B2 and B3), GPS (L1, L2 and L5), GLONASS (L1 and L2) and Galileo (E1 and E5) multi-constellation multi-frequency signals, and has multiple positioning modes such as standard single-point positioning, dual-frequency ionosphere-free positioning, satellite-based enhanced positioning and precise single-point positioning.

[0130] 2. Automatic selection method of positioning mode in Beidou position tracking terminal

[0131] The present invention determines the area where the aircraft is located according to the standard single point positioning result output by the positioning module in the Beidou position tracking terminal 10, and establishes the positioning mode priority selection order of the positioning module in combination with the signal availability, in the order of precise single point positioning, dual-frequency ionosphere-free positioning, satellite-based augmented positioning and standard single point positioning, the precise single point positioning mode is preferentially selected in the area where precise single point positioning service is provided, and the satellite-based augmented positioning mode is preferentially selected in the area where satellite-based augmented service is provided. In other areas (i.e., the precise single point positioning service area and the area outside the satellite-based augmented service area) and when the precise single point positioning signal and the satellite-based augmented service signal are unavailable, the dual-frequency ionosphere-free positioning mode is preferentially selected, and the standard single point positioning mode is selected when the above-mentioned precise single point positioning signal, satellite-based augmented positioning signal and dual-frequency ionosphere-free positioning signal are all unavailable. In this embodiment, the precise point positioning service area is officially defined as the surface of the earth in China and its surrounding areas (the area between 75 and 135 degrees east longitude and 10 and 55 degrees north latitude) and the near-earth area extending to an altitude of 1,000 kilometers in the air; the satellite-based augmentation service area refers to the area on the earth that can receive the signals of the three GEO satellites B1C and B2a with PRNs of 130, 143 and 144.

[0132] 3. Using one-way communication between front and rear cabins to achieve aircraft emergency navigation

[0133] The communication module forwards the second positioning parameter output by the positioning module and the third positioning parameter collected by the GNSS antenna 9 to the ground monitoring center 12 in the form of a short message through the medium earth orbit (MEO) satellite / geostationary orbit (GEO) satellite in the Beidou-3 satellite 17, and also transmits it unidirectionally to the airborne interface device 8 for storage and standby through the front and rear cabin communication links. Under normal operating conditions, no data transmission is performed with the CMU / ATSU and EFB and other equipment. It is only provided as a temporary navigation source to the front cabin equipment and crew members as a reference under special operating conditions (i.e., the front cockpit navigation equipment is damaged by human beings or the equipment fails and cannot normally provide the required navigation information to the flight management system 4), so as to realize emergency navigation of the aircraft.

[0134] 4. Realize the aircraft ACARS+ function by using two-way communication between the front and rear cabins

[0135] When ACARS is unable to transmit large amounts of text, pictures, images, voice and other information content that is urgently needed by civil aviation users, especially when it is unable to support current safety business scenarios of big data applications such as wireless quick access recorder (QAR) data transmission, EFB system, navigation database, obstacle data and entertainment system data update, the CMU / ATSU in the front cabin of the aircraft can complete the two-way transmission of the above data content between the aircraft and the ground through the AID and the front and rear cabin communication links, thereby increasing the transmission frequency of key safety business information and realizing the ACARS+ function.

[0136] 5. Installation plan for BeiDou-3 satellite payload and BeiDou position tracking terminal communication module

[0137] In order to improve the utilization rate of the BeiDou-3 space constellation, an international search and rescue payload is installed on the BeiDou-3 satellite 17, except for the BeiDou short message payload installed. Accordingly, in addition to installing the necessary short message communication module and antenna, the BeiDou position tracking terminal 10 also needs to install an international search and rescue module and antenna and an Iridium communication module and antenna in order to provide international search and rescue services and Iridium communication services, so as to achieve the matching and integration between the satellite communication payload and the terminal communication mode.

[0138] 6. Beidou Position Tracking Terminal Communication Mode Switching Method

[0139] The Beidou position tracking terminal 10, which is equipped with a short message communication module, an international search and rescue module, and an Iridium communication module at the same time, needs to establish an automatic switching method of the communication mode based on the aircraft position information output by the positioning module in the terminal, as well as the working status of the short message communication module, the international search and rescue module, and the Iridium communication module in the terminal, with the Beidou regional short message service area as the boundary. The communication priorities of each module outside the Beidou regional short message service area are defined as the international search and rescue module, the Iridium communication module, and the Beidou global short message communication module, respectively. The communication priorities of each module within the Beidou regional short message service area are defined as the international search and rescue module, the Beidou regional short message communication module, and the Iridium communication module, respectively. Selecting the communication mode by switching the working module can effectively reduce the frequency interference problem between different communication services while ensuring the quality of communication services.

[0140] 7. Select Beidou short message communication satellite according to the number of visible satellites and satellite elevation angle

[0141] In China and surrounding areas, the short message communication module of the Beidou location tracking terminal 10 uses all GEO satellites that meet the elevation mask requirements to complete the Beidou regional short message communication data forwarding; globally, the short message communication module of the Beidou location tracking terminal 10 uses the n MEO satellites with the largest elevation angles (assuming that the number of satellites that meet the elevation mask requirements is k, then n≤k) to complete the Beidou global short message communication data forwarding. Beidou return communication satellites give priority to using the same satellite to complete the return data forwarding of the ground monitoring center 12. International search and rescue services can also use this method to select MEO satellites that forward user uplink signals and payload downlink signals, as well as MEO satellites and inclined geosynchronous orbit (IGSO) satellites that forward return link signals or user downlink signals, and are even suitable for the selection of communication satellites after satellites are equipped with communication payloads and terminals are equipped with communication modules.

[0142] 8. Forwarding strategy for synchronously transmitting communication data using multiple Beidou satellites

[0143] When the single transmission data between the communication module and the ground monitoring center 12 exceeds the maximum length of a single message, the data to be transmitted must be split into several data sub-packets, and a forwarding strategy for synchronous transmission of communication data by multiple Beidou satellites (MEO, IGSO and GEO) can be used. The data sub-packets are evenly distributed according to the available satellites, and the data to be transmitted to each satellite is added to the queue buffer. On the basis of serial forwarding of a single satellite, synchronous forwarding of multiple satellites is realized, which reduces the data transmission and service response time, and realizes a higher frequency of one-way position reporting and two-way service transmission.

[0144] 9. Design scheme for parameters and format of B2b downlink signal message for Beidou global short message and international search and rescue return communication

[0145] The present invention designs a short message parameter definition and format arrangement scheme based on the B-CNAV3 format navigation message, and defines parameters and divides the number of bits of 486 bits of data before error correction coding for each sub-data packet message. Beidou regional short message uplink and downlink signals, Beidou global short message uplink signals, international search and rescue user uplink signals, and payload downlink signals can all be designed using this scheme.

[0146] 10. Aircraft using front and rear cabin communication links and Beidou short message function

[0147] After installing the BeiDou position tracking terminal 10 on the aircraft and establishing a communication link between the front and rear cabins, the terminal's positioning function and short message function, as well as the one-way and two-way communication modes of the communication link, are used to transmit the aircraft position and other information stored in the front cabin from the rear cabin terminal to the front cabin and the output results of the domestic multi-mode receiver (MMR) in the front cabin, which are displayed on the EFB device through the AID as the aircraft's backup navigation source, providing the flight crew with a BeiDou-3 emergency navigation communication reference.

[0148] The technical solution disclosed in the present invention has the following advantages:

[0149] 1. The present invention provides a solution for upgrading the positioning module and communication module of the Beidou position tracking terminal 10: the positioning module upgrade solution can utilize multiple frequency navigation signals to perform real-time positioning of the aircraft, get rid of the limitation of only being able to track the aircraft using B1I signals, and greatly improve the positioning accuracy and reliability of the Beidou position tracking terminal 10; the communication module upgrade solution can prioritize the working communication module according to whether it is in the Beidou regional short message communication service area while ensuring the highest priority of international search and rescue services, thereby alleviating or even avoiding the frequency interference problem between different communication services; derived from technical points 1, 2, 5 and 6.

[0150] 2. The present invention provides a Beidou short message communication service message arrangement scheme and data forwarding strategy: designs the effective information type (50) and message data (session parameters and number of bits) of the B-CNAV3 format navigation message broadcast by the downlink signal of the global short message service Beidou B2b user, providing a reference for the formulation and update of the ICD file of the Beidou regional short message and global short message communication service users; designs a short message packet data multi-satellite synchronous forwarding strategy based on the visible satellite elevation angle, reduces the transmission time and service response delay, and improves the frequency of use and data transmission efficiency; originates from technical points 7, 8 and 9.

[0151] 3. The present invention provides a design scheme for the communication link between the front and rear cabins 2 of an aircraft and an airborne emergency navigation and communication system architecture: a communication link is established between the airborne interface device 8 in the front electronic cabin and the Beidou position tracking terminal 10 in the rear cabin 2, and the aircraft parameters and large data transmission under normal circumstances and the emergency navigation function in emergency situations are realized through the communication link; an airborne emergency navigation and communication system architecture based on the Beidou short message communication service is established to accelerate the formulation of Beidou aircraft tracking standards and equipment development as well as the implementation of civil aviation ACARS+ services; derived from technical points 3, 4 and 10.

[0152] 4. Carry the Beidou position tracking terminal 10 with Beidou-3 short message communication function on civil aviation passenger aircraft and other aircraft, upgrade the positioning module and communication module of the Beidou position tracking terminal 10, optimize the positioning mode, communication mode, short message forwarding strategy, message format, rear cabin 2 communication mechanism and navigation communication system architecture, improve the navigation positioning accuracy, data transmission frequency and communication service scope, refine the aircraft onboard communication mechanism and emergency navigation communication architecture, ensure that the aircraft can still provide reliable monitoring and tracking and emergency navigation communication services under special conditions such as communication interruption, natural disasters and emergencies, and protect the safety of aircraft and people’s lives and property.

[0153] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Claims

1. An aircraft based on Beidou short message, characterized in that: The aircraft includes: the forward electronics compartment and the rear passenger compartment; The front electronic compartment includes: airborne interface equipment, inertial measurement unit, flight management system, electronic flight bag, multi-mode receiver and communication management unit / air traffic service unit; The inertial measurement unit is connected to the airborne interface device and the flight management system respectively, the flight management system is connected to the multi-mode receiver and the communication management unit / air traffic service unit respectively, and the communication management unit / air traffic service unit, the multi-mode receiver and the electronic flight bag are all connected to the airborne interface device; The rear cabin includes: a Beidou position tracking terminal and a GNSS antenna; the Beidou position tracking terminal includes a positioning module and a communication module; the positioning module is connected to the airborne interface device and the GNSS antenna respectively; the communication module is connected to the positioning module and the GNSS antenna respectively; The function of the GNSS antenna is to receive multi-constellation and multi-frequency signals; The positioning module is used to receive multi-constellation multi-frequency point signals, determine the final position of the aircraft based on the multi-constellation multi-frequency point signals by using the positioning mode automatic selection method, and send the second positioning parameters to the airborne interface device for storage; the second positioning parameters include: the final positioning position, time and speed of the aircraft; The positioning module has multiple positioning modes; the positioning modes include: standard single-point positioning, dual-frequency ionosphere-free positioning, satellite-based augmented positioning and precise single-point positioning; an inertial measurement unit, for measuring IMU attitude data of the aircraft and transmitting the IMU attitude data to the flight management system and the onboard interface device; a multi-mode receiver for calculating MMR navigation data of the aircraft and transmitting the MMR navigation data to the flight management system and the onboard interface device; The onboard interface device is also used to store first positioning parameters; the first positioning parameters include IMU attitude data and MMR navigation data; When the situation is normal, the onboard interface device sends the first positioning parameter to the electronic flight bag for display; the flight management system formulates an optimal flight plan according to the first positioning parameter and realizes automatic control of the flight mission; When there is a special situation, the airborne interface device sends the second positioning parameter to the electronic flight bag for display; the airborne interface device sends the second positioning parameter to the flight management system through the communication management unit / air traffic service unit, so that the flight management system formulates the best flight plan according to the second positioning parameter and realizes automatic control of the flight mission; the special situation is when the multi-mode receiver and / or the inertial measurement unit cannot work; The communication module is used to receive the second positioning parameter sent by the positioning module, and forward it to the GNSS antenna in the form of a short message, so that the GNSS antenna sends it to the ground monitoring center through the Beidou-3 satellite.

2. The Beidou short message-based aircraft according to claim 1, characterized in that: The communication management unit / air traffic service unit is used to generate ACARS+ instructions, and send the ACARS+ instructions to the ground monitoring center through the airborne interface device, the communication module, the GNSS antenna and the Beidou-3 satellite in sequence; when the ground monitoring center receives the ACARS+ instructions, the ACARS+ data is sent to the airborne interface device through the Beidou-3 satellite, the GNSS antenna and the communication module in sequence for storage; the ACARS+ instructions are instructions for the crew to request the ground to upload large data; the ACARS+ data are data greater than the set data volume.

3. The Beidou short message-based aircraft according to claim 1, characterized in that: The front electronic compartment also includes: a satellite / VHF communication unit, which is connected to the ground monitoring center and the communication management unit / air traffic service unit respectively; The satellite / VHF communication unit is used to receive downlink instructions and uplink instructions; the downlink instructions are generated by the communication management unit / air traffic service unit; the downlink instructions include: air traffic control ATC request instructions, short-distance downlink data instructions and satellite communication SATCOM request instructions; the ATC request instruction is an instruction for the crew to request clearance from the ground; the short-distance downlink data instruction is an instruction for the short-distance crew to issue downlink data to the ground; the SATCOM request instruction is an instruction for the long-distance crew to request data from the ground; The upload instruction is generated by the ground monitoring center; the upload instruction includes: air traffic control ATC approval instruction, short-distance upload data instruction and satellite communication SATCOM broadcast instruction; the ATC approval instruction is an instruction for the ground to approve the release to the crew; the short-distance upload data instruction is an instruction for the ground to issue upload data to the crew at a short distance; the SATCOM broadcast instruction is an instruction for the ground to broadcast data to the crew at a long distance; The satellite / very high frequency communication unit sends the downlink instruction to the ground monitoring center, and sends the uplink instruction to the communication management unit / air traffic service unit; the communication management unit / air traffic service unit sends the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction to the flight management system, so that the flight management system formulates the best flight plan and realizes automatic control of the flight mission according to the first positioning parameter, the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction; or formulates the best flight plan and realizes automatic control of the flight mission according to the second positioning parameter, the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction; or formulates the best flight plan and realizes automatic control of the flight mission according to the third positioning parameter, the ATC request instruction, the ATC approval instruction, the short-distance downlink data instruction and the short-distance uplink data instruction; The communication management unit / air traffic service unit sends the upload instruction and the download instruction to the airborne interface device for storage.

4. The Beidou short message-based aircraft according to claim 1, characterized in that: The method of automatically selecting the positioning mode is used to determine the final position of the aircraft, and the specific steps include: Step S1: First, use the single-frequency signal in each constellation to perform standard single-point positioning to obtain a standard single-point positioning result; Step S2: judging whether the area where the aircraft is located is within the precise point positioning service area according to the standard point positioning result; if the aircraft is within the precise point positioning service area, judging whether there is a precise point positioning signal available; if there is a precise point positioning signal available, selecting the precise point positioning mode for positioning, and outputting the precise point positioning result as the final positioning position; if there is no precise point positioning signal available, executing "step S3"; if the aircraft is outside the precise point positioning service area, executing "step S3"; Step S3: Determine whether the area where the aircraft is located is within the satellite-based augmentation service area; if the aircraft is within the satellite-based augmentation service area, determine whether there is a satellite-based augmentation service signal available; if there is a satellite-based augmentation signal available, select the satellite-based augmentation positioning mode for positioning, and output the satellite-based augmentation positioning result as the final positioning position; if there is no satellite-based augmentation signal available, execute "step S4"; if the aircraft is outside the satellite-based augmentation service area, execute "step S4"; Step S4: Determine whether a dual-frequency signal is available. If a dual-frequency signal is available, select the dual-frequency ionosphere-free positioning mode for positioning, and output the dual-frequency ionosphere-free positioning result as the final positioning position; if no dual-frequency signal is available, select the standard single-point positioning mode, and output the standard single-point positioning result as the final positioning position.

5. The Beidou short message-based aircraft according to claim 2, characterized in that: The communication module includes an international search and rescue module, a global short message communication module, an Iridium communication module and a Beidou regional short message module. The communication module adopts an automatic switching communication method for satellite communication. The steps of the automatic switching communication method specifically include: Step S5: Determine whether the current communication working module is the international search and rescue module; if the current communication working module is the international search and rescue module, close the regional short message communication module, the global short message communication module and the Iridium communication module, and continue to use only the international search and rescue module for satellite communication; if the current communication working module is not the international search and rescue module, execute step S6; Step S6: judging whether the area where the aircraft is located is within the Beidou regional short message service area according to the final positioning position; if it is within the Beidou regional short message service area, executing step S7; if it is outside the Beidou regional short message service area, executing step S8; Step S7: Determine whether the current communication working module is the Beidou regional short message communication module; if the current communication working module is the Beidou regional short message communication module, close the international search and rescue module, the global short message communication module and the Iridium communication module, and continue to use only the Beidou regional short message module for satellite communication; if the current communication working module is not the Beidou regional short message communication module, use the global short message communication module for satellite communication; Step S8: Determine whether the current communication working module is the Iridium communication module; if the current communication working module is the Iridium communication module, close the international search and rescue module, the global short message communication module and the regional short message communication module, and continue to use only the Iridium communication module for satellite communication; if the current communication working module is not the Iridium communication module, use the global short message communication module for satellite communication.

6. The Beidou short message-based aircraft according to claim 2, characterized in that: The communication module sends data to the BeiDou-3 satellite in a packet-by-packet synchronous forwarding manner.

7. The Beidou short message-based aircraft according to claim 6, characterized in that: The data sub-packets obtained after packetization include: session ID, packet identification, packet quantity, packet ID, packet satellite PRN number and packet information.

8. A Beidou short message emergency navigation and communication system, characterized in that: The system comprises the aircraft according to any one of claims 1 to 7, a BeiDou-3 satellite and a ground monitoring center; The communication module of the aircraft synchronously forwards the second positioning parameters to the ground monitoring center through the Beidou-3 satellite sub-packets.

9. The Beidou short message emergency navigation and communication system according to claim 8, characterized in that: Each satellite in the BeiDou-3 satellite is equipped with a regional short message payload and antenna, a global short message payload and antenna, and an international search and rescue payload and antenna.

10. The Beidou short message emergency navigation and communication system according to claim 8, characterized in that: The ground monitoring center includes: a command aircraft antenna, a command aircraft, a ground monitoring terminal and a VHF ground terminal; the command aircraft antenna is connected to the ground monitoring terminal through the command aircraft, and the VHF ground terminal is connected to the satellite / VHF communication unit.

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