Method for real-time display and control of low-orbit satellite communication vehicle positioning information for military commercial vehicle fleet

Abstract

This invention relates to a method for real-time display and control of vehicle positioning information via low-Earth orbit satellite communication for military and commercial vehicle fleets. It includes: collecting and preprocessing positioning data; classifying and labeling serialized data as current location data and historical retransmission data; constructing a real-time sub-channel, dynamically adjusting the transmission frequency based on link quality, and encrypting the current location data using the national standard SM9 encryption; establishing a DTN retransmission channel, fragmenting, encrypting, and scheduling the transmission of historical data; receiving and classifying real-time and historical data on the platform; visually displaying real-time positioning and playback trajectories, and reconstructing continuous trajectories through data fusion; and defining electronic fences to implement boundary crossing alarms. This invention, through a dual-channel transmission architecture and dynamic adjustment strategy, solves the problems of data loss and out-of-order delivery caused by intermittent low-Earth orbit satellite link connections, ensuring the integrity, real-time nature, and security of positioning data, and improving the accuracy and continuity of fleet management.

Description

Technical Field

[0001] This invention relates to the field of communication and vehicle monitoring technology, and in particular to a method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets. Background Technology

[0002] Currently, military vehicle positioning suffers from limited coverage, numerous signal blind spots in complex terrains such as the field, offshore, and border regions, and susceptibility to interference. Although the rapid development of low-Earth orbit (LEO) satellite communication constellations has mitigated these shortcomings to some extent with their wide-area coverage and low-latency transmission, current technologies typically integrate GPS / BeiDou dual-mode positioning modules into vehicle-mounted terminals (such as SBOX). Positioning data is encrypted and transmitted back to the military intranet command platform via LEO satellite communication links, ultimately enabling real-time location display, historical trajectory playback, and electronic fence control functions. However, in large-scale, highly dynamic application scenarios involving military convoys, LEO satellites move at high speeds relative to the ground, and the overhead communication window between a single satellite and a fixed ground station is short (typically only a few minutes). This causes ground convoy terminals to frequently experience a cycle of "satellite overhead connection - satellite departure disconnection - switching to the next satellite for reconnection." This highly dynamic and intermittent connection characteristic makes data packets highly susceptible to loss, out-of-order delivery, or duplication during transmission. The TCP protocol, widely used in traditional terrestrial networks, heavily relies on stable end-to-end connections and relatively fixed round-trip time (RTT). In low-Earth orbit satellite links characterized by frequent interruptions and severe latency fluctuations, congestion control mechanisms can misjudge link status, leading to a sharp decline in transmission performance or even complete failure. Consequently, the positioning data stream received by the command platform may suffer from severe timestamp corruption and data gaps, resulting in distorted "real-time location" and discontinuous jumps or breaks in "track playback," failing to provide accurate and coherent situational information for command and decision-making. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for real-time display and management of vehicle positioning information via low-Earth orbit satellite communication for military and commercial vehicle fleets. Through a dual-channel transmission architecture and dynamic adjustment strategy, it solves the problems of data loss and out-of-order delivery caused by intermittent low-Earth orbit satellite link connections, ensuring the integrity, real-time nature, and security of positioning data, and improving the accuracy and continuity of fleet management.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for real-time display and control of low-Earth orbit satellite communication vehicle positioning information for military and commercial vehicle fleets includes the following steps: S1: Collect and preprocess location data; S11: Vehicle-mounted SBOX collects positioning data; The vehicle-mounted SBOX has a built-in GPS / BeiDou dual-mode positioning module. The dual-mode positioning module receives satellite signals in real time. When it captures signals from at least 4 satellites at the same time, it starts data acquisition and collects positioning data at a preset frequency. Otherwise, it attempts to reconnect at a frequency of 1 Hz and records the signal loss status. The collected positioning data is temporarily stored in the SBOX local cache and a directory is created according to the vehicle ID and the collection date.

[0005] Location data includes vehicle position, speed, heading, and timestamp (accurate to milliseconds). Vehicle position includes longitude, latitude, and altitude.

[0006] The preset frequency is 10 Hz.

[0007] The vehicle-mounted SBOX is an embedded integrated information processing and secure communication terminal for vehicles.

[0008] S12: Preprocessing positioning data; The positioning data is processed by timestamp alignment, outlier filtering, and coordinate system unification, and preprocessed data in a standard format is serialized and output. S121: Timestamp alignment; Correct the local RTC clock and unify the timestamp to UTC standard time.

[0009] S122: Unified coordinate system; Set the coordinate system to the CGCS2000 standard coordinate system. Read the WGS-84 coordinate system parameters of the vehicle position in the positioning data, and use the seven-parameter coordinate transformation method to convert the WGS-84 coordinate system to the CGCS2000 standard coordinate system.

[0010] The WGS-84 coordinate system is the global geocentric coordinate system used by GPS.

[0011] The CGCS2000 standard coordinate system is the coordinate system used by China's BeiDou system.

[0012] S123: Outlier filtering; A preset jump detection threshold is set. The location data is compared with the jump detection threshold. If the jump detection threshold is exceeded, the location data is marked as abnormal and the marked abnormal location data is filtered out.

[0013] Jump detection thresholds include position jump thresholds, velocity jump thresholds, etc. Based on the vehicle location, compare the distance ∆d between adjacent timestamps of the vehicle location to see if it exceeds the location jump threshold. If it does, it is considered a location jump and marked as abnormal; otherwise, it is considered normal.

[0014] Based on vehicle speed, the absolute value of the difference between vehicle speeds at adjacent timestamps is compared to see if it exceeds a speed jump threshold. If it does, it is considered a speed jump and marked as abnormal; otherwise, it is considered normal.

[0015] S124: Serialization; The preprocessed data is serialized in standard JSON format to obtain serialized data. The serialized data structure includes fields such as vehicle ID, corrected timestamp, CGCS2000 longitude, CGCS2000 latitude, altitude, driving speed, and heading angle.

[0016] S2: Classify and label data types; S21: Determine whether the serialized data is current location data or historical retransmission data; Iterate through the serialized data to obtain the corrected timestamp, and compare the difference between the corrected timestamp and the current local clock time with ≤1s. If the difference is ≤1s, it is determined to be the current location data; otherwise, it is determined to be historical retransmission data.

[0017] S22: Add type marker; Add a type marker of RT-01 to the current location data and store it in the SBOX local DRAM cache (read / write speed ≥1GB / s), giving priority to occupying transmission resources; Add a type marker of HT-02 to the historical retransmission data; store the historical retransmission data in the local NAND Flash cache of SBOX according to the order of timestamps; DRAM cache is dynamic random access memory used to temporarily store data at the current location that needs to be processed quickly.

[0018] NAND Flash cache is a non-volatile flash memory used as a large-capacity persistent cache to store historical data.

[0019] S23: Establish a categorized data index table; An index table is created for each of the categorized compressed data, and the index table records the storage address and transmission status, etc. The transmission status includes pending transmission, in transmission, and completed.

[0020] S3: Construct a real-time sub-channel for encrypted transmission of current location data; S31: Real-time monitoring of link status; The vehicle-mounted SBOX collects link connection status in real time, including parameters such as signal-to-noise ratio (SNR), bit error rate (BER), and remaining overhead time. It also sets link quality grading thresholds to determine the link quality level. If SNR≥15dB, BER≤10 -4Determined as a high-quality link; if 10dB≤SNR<15dB, 10 -4 <BER≤10 -3 If the link is classified as a normal link, and the SNR is less than 10 dB and the BER is greater than 10 dB, then it is considered a normal link. -3 It was determined to be a low-quality link.

[0021] S32: Encapsulates real-time data packets; A lightweight UDP-based transport protocol encapsulates current location data to generate real-time data packets. The real-time data includes a frame header, payload data, and a frame trailer.

[0022] The frame header includes the vehicle ID, data type identifier, payload length, and checksum, etc. The vehicle ID is identified by the vehicle ID hash value; The data type identifier is fixed as RT-01; The payload data is serialized current position data; The frame end includes the national cryptographic standard SM9 signature, etc.

[0023] S33: Encrypted using the national standard SM9 encryption; The SM9 identifier cipher algorithm is used to encrypt real-time data packets at the link layer. Each time a real-time data packet is sent, the payload data of the data packet is updated to "transmitting" status in the index table.

[0024] S34: Dynamically transmit real-time data packets; If it is a high-quality link, send real-time data packets at a frequency of 10Hz. For ordinary links, the LZ77 compression algorithm is used to compress real-time data packets, and the compressed real-time data packets are sent at a frequency of 5Hz. If the link is of poor quality, compressed real-time data packets are sent at a frequency of 2Hz and FEC erasure coding is used for transmission. Based on the remaining overpass time, if the remaining overpass time is less than or equal to 3 seconds, only the real-time data packet with the latest timestamp will be transmitted.

[0025] Each real-time data packet has one retransmission opportunity, with a retransmission interval of 50ms; FEC erasure coding is an error control method that proactively adds redundant information before errors occur in data transmission, automatically detecting and correcting a certain number of errors. This invention only uses this technology and does not make any innovations, so the principle and process of the method will not be described in detail.

[0026] S35: Exception handling; If retransmission fails, the real-time data packet is marked as pending retransmission, and the pending real-time data packet is stored in the NAND Flash cache.

[0027] If the satellite connection is lost, transmission will be stopped immediately, and newly generated real-time data packets of the current location will be temporarily stored in the DRAM cache. Once the satellite reconnects, they will be transmitted with priority.

[0028] S4: Establish a DTN retransmission channel for encrypted transmission of historical retransmission data; S41: Historical data retransmission is fragmented and packaged; The historical data is iterated through and divided into data shards of 100 records each, arranged chronologically. A unique shard identifier is generated, which includes the vehicle ID, start timestamp, end timestamp, and shard sequence number. Each data shard includes metadata such as the number of data records, shard sequence number, time range, and checksum.

[0029] S42: Encapsulate data fragments into data bundles; Data fragments are encapsulated into DTN Bundles according to the DTN protocol (RFC 5050); each bundle includes metadata such as creation time, time to live, source, and destination. Creation time is the timestamp of when the data bundle was first created and encapsulated; Time to live is the maximum duration for which a data bundle is allowed to remain in a network; The source is the network endpoint identifier that generates and first sends the data bundle; The destination is the network endpoint identifier to which the data bundle will ultimately be delivered; S43: End-to-end encryption is performed using the SM9 identifier cryptographic algorithm; To prevent data tampering and forgery, the vehicle-mounted SBOX uses the SM9 identifier cryptographic algorithm to encrypt the data bundle and performs SM9 signature on the data bundle; each vehicle-mounted SBOX is pre-distributed with a private key bound to the platform's unique identifier, and the vehicle-mounted SBOX uses the destination terminal for encryption to ensure that only the designated destination terminal can decrypt the data.

[0030] S44: Schedule the transmission of data bundles; The SBOX terminal monitors the overhead status of low-Earth orbit satellites in real time. When the remaining overhead time is ≥10 seconds, it initiates DTN retransmission to transmit data bundles. It modifies the historical retransmission data within the data bundle in the index table to "transmitting". It also records the transmission progress. After each data bundle is transmitted, it waits for a receiving response. If no receiving response is received after 5 seconds, the data bundle is marked as pending retransmission. When the next satellite overhead occurs and DTN retransmission is initiated, it is retransmitted first. If the reception is successful, the historical retransmission data within the data bundle fragment is updated in the index table to "transmission completed".

[0031] The transmission progress includes the number of bytes sent and the number of bytes remaining.

[0032] For data bundles that are not fully transmitted within the time it takes for a single satellite to pass overhead, the data bundles will continue to be transmitted when the next satellite passes overhead and DTN retransmission is initiated, based on the transmission progress, to ensure that the interrupted transmission is resumed.

[0033] S5: The platform receives data and stores it in categories; The platform receives real-time data packets and data bundles respectively, and after parsing and verification, stores them in the real-time database and the historical retransmission database respectively.

[0034] S51: Receive and store the current location data of real-time data packets; The platform uses a UDP port to receive real-time data packets. After parsing, SM9 decryption, and signature verification, it extracts the payload data. It obtains the vehicle ID and timestamp, deduplicates based on the vehicle ID and timestamp, removes duplicate real-time data packets, verifies the data type and checksum, and after passing the verification, stores the current location data in the payload data into the real-time database and sends it to the WebSocket service in real time for front-end real-time updates.

[0035] WebSocket establishes a persistent, full-duplex communication channel between the user's browser (or client app) and the server. Upon receiving the current location data, the WebSocket service immediately and automatically pushes it to all online command terminals or large screens.

[0036] S52: Receive and store the historical retransmission data of the data bundle; The platform deploys DTN convergence nodes to receive data bundles, verify the integrity of fragments, obtain data fragments after SM9 decryption and signature verification, extract historical retransmission data, deduplicate data according to fragment identifiers to avoid storing the same data fragment repeatedly, and sort the extracted historical retransmission data by timestamp and store it in the historical retransmission database.

[0037] S6: Visual presentation; Trajectory is reconstructed based on a hierarchical completion strategy, and real-time positioning and trajectory playback are displayed. Different rendering is used for different types of data.

[0038] S61: Displays real-time location; The front-end obtains the current location data through the WebSocket service, and marks the vehicle's location on the electronic map in real time based on the vehicle's location in the current location data. The vehicle ID, speed, and timestamp are displayed when the mouse hovers over the vehicle.

[0039] S62: Display the playback trajectory; S621: Data fusion and trajectory reconstruction; First, in response to the user's selection of vehicle ID and time range, the system obtains the current location data and historical retransmission data within the specified vehicle ID and time range from the real-time database and the historical retransmission database, and performs global sorting based on the timestamp. Then, the time difference between two adjacent data points in the global sort is checked. If the time difference is ≤1 second, it is considered normal data. If 1 second < time difference ≤ 8 seconds, linear interpolation is used to complete the missing data. The location of the missing point is calculated by linear interpolation based on the latitude and longitude of the two points and the time ratio, and marked as interpolated data. If 8 seconds < time difference ≤ 30 seconds, trajectory estimation is used to complete the data based on vehicle speed and heading angle. The speed and heading angle of the data point with the earlier timestamp are obtained. Assuming that the vehicle moves at a constant speed in a straight line during this time period, the position of each moment in the missing time period is estimated and marked as estimated data. If the time difference exceeds 30 seconds, no data is completed, and the period between two adjacent data points is marked as a disconnected time period.

[0040] Finally, the vehicle positions from the normal data, interpolated data, and extrapolated data are used to generate trajectory curves based on timestamps.

[0041] S622: Render and display playback trajectory; The rendering displays the trajectory curves, using different colors to represent normal data, interpolated data, and extrapolated data: normal data is rendered in blue, interpolated data in orange, and extrapolated data in red. Disconnected periods are connected by dashed lines.

[0042] S7: Regional Control; Users define electronic fences, set fence names and alarm rules. According to the alarm rules, the platform compares the vehicle's location with the electronic fence boundary in real time. If the vehicle's location exceeds the electronic fence boundary, an alarm is triggered, a pop-up notification and an audible alarm are pushed, and an alarm log is recorded.

[0043] The alarm log includes vehicle ID, time, fence name, etc.

[0044] Electronic fences are geometric areas that users can customize using a map interface, such as circles, polygons, and polylines.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention adopts a dual transmission architecture of real-time sub-channel and DTN retransmission channel. The real-time channel adopts a lightweight UDP protocol and integrates a dynamic frequency adjustment strategy, which significantly reduces data loss and out-of-order due to link jitter and interruption. The DTN retransmission channel effectively ensures the integrity and order of historical positioning data through breakpoint resume transmission and store-and-forward, completely solves the problem of data loss and out-of-order, avoids the problem of the performance of traditional TCP protocol in star-ground dynamic link, and ensures that the integrity of positioning data transmission exceeds 99% and the trajectory playback is continuous without breakage.

[0046] (2) This invention uses three preprocessing steps: timestamp alignment, coordinate system unification, and outlier filtering to reduce positioning errors. It is encrypted with the national cryptographic SM9 algorithm throughout the entire process, and the entire link from transmission to storage is protected against tampering and theft, ensuring the accuracy and security of positioning data.

[0047] (3) This invention classifies, marks, and caches the collected positioning data through the vehicle-mounted SBOX, prioritizes the transmission of current location data to ensure the real-time nature of the positioning data, reliably stores and asynchronously transmits historical data, and performs data fusion and trajectory reconstruction on the platform to effectively fill the data gaps caused by transmission interruption, generate continuous and smooth vehicle trajectories, and provide accurate and coherent situational information for command and decision-making.

[0048] (4) This invention dynamically adjusts the transmission frequency and compression strategy of real-time data according to the link quality. It maintains high-frequency updates under high-quality links and enables compression and erasure coding mechanisms under poor-quality links, thus balancing transmission efficiency and reliability. The DTN retransmission channel is based on intelligent scheduling transmission through satellite over-the-top windows, realizing reasonable allocation of bandwidth resources and breakpoint resumption, optimizing resource utilization, and maintaining stable communication in signal blind spots or poor link environments such as the wild, the sea, and the border, with no dead zones in coverage.

[0049] (5) This invention provides multi-dimensional management functions such as real-time location display, historical trajectory playback, and electronic fence alarm. The trajectory playback supports data interpolation and trajectory estimation, clearly distinguishes normal data, complete data, and disconnection periods, and renders them with differentiated colors to enhance the readability and analytical value of the trajectory. It defines the shape of the electronic fence and alarm rules to realize real-time monitoring and alarm of vehicles crossing the boundary, thereby improving the refinement and initiative of fleet management. Attached Figure Description

[0050] Figure 1 This is a flowchart illustrating the steps of the method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets according to the present invention. Detailed Implementation

[0051] To provide a further understanding of the purpose, structure, features, and functions of the present invention, detailed descriptions are provided below with reference to specific embodiments.

[0052] like Figure 1 A method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets includes the following steps: S1: Collect and preprocess location data; S11: Vehicle-mounted SBOX collects positioning data; The vehicle-mounted SBOX has a built-in GPS / BeiDou dual-mode positioning module. The dual-mode positioning module receives satellite signals in real time. When it captures signals from at least 4 satellites at the same time, it starts data acquisition and collects positioning data at a preset frequency. Otherwise, it attempts to reconnect at a frequency of 1 Hz and records the signal loss status. The collected positioning data is temporarily stored in the SBOX local cache and a directory is created according to the vehicle ID and the collection date.

[0053] Location data includes vehicle position, speed, heading, and timestamp (accurate to milliseconds). Vehicle position includes longitude, latitude, and altitude.

[0054] The preset frequency is 10 Hz.

[0055] The vehicle-mounted SBOX is an embedded integrated information processing and secure communication terminal for vehicles.

[0056] S12: Preprocessing positioning data; The positioning data is processed by timestamp alignment, outlier filtering, and coordinate system unification, and preprocessed data in a standard format is serialized and output. S121: Timestamp alignment; Correct the local RTC clock and unify the timestamp to UTC standard time.

[0057] S122: Unified coordinate system; Read the WGS-84 coordinate system parameters of the vehicle position in the positioning data, and use the seven-parameter coordinate transformation method to convert the WGS-84 coordinate system to the CGCS2000 standard coordinate system; The WGS-84 coordinate system is the global geocentric coordinate system used by GPS.

[0058] The CGCS2000 standard coordinate system is the coordinate system used by China's BeiDou system.

[0059] S123: Outlier filtering; A preset jump detection threshold is set. The location data is compared with the jump detection threshold. If the jump detection threshold is exceeded, it is marked as abnormal.

[0060] Jump detection thresholds include position jump thresholds, velocity jump thresholds, etc. Based on the vehicle location, compare the distance ∆d between adjacent timestamps of the vehicle location to see if it exceeds the location jump threshold. If it does, it is considered a location jump and marked as abnormal; otherwise, it is considered normal.

[0061] Based on vehicle speed, the absolute value of the difference between vehicle speeds at adjacent timestamps is compared to see if it exceeds a speed jump threshold. If it does, it is considered a speed jump and marked as abnormal; otherwise, it is considered normal, and the marked abnormal data is filtered out. Preemptively removing location and speed jump data prevents abnormal data from interfering with command and control decisions, while also reducing invalid data transmission and lowering satellite link bandwidth usage.

[0062] By aligning timestamps, standardizing coordinate systems, and filtering anomalies in the vehicle-mounted SBOX, the computational burden on the platform server is significantly reduced, avoiding delays caused by large-scale data cleaning on the server side. The unified timestamps use UTC time and the CGCS2000 coordinate system, completely eliminating display problems such as trajectory misalignment caused by terminal clock drift or coordinate system differences.

[0063] S124: Serialization; The preprocessed data is serialized into serialized data using standard JSON format. The serialized data structure includes fields such as vehicle ID, corrected timestamp, CGCS2000 longitude, CGCS2000 latitude, altitude, driving speed, and heading angle. A unified output format ensures data standardization. The JSON standard format offers strong compatibility, facilitates platform parsing and integration with multiple systems, and provides a clear and scalable data structure.

[0064] S2: Classify and label data types; S21: Determine whether the serialized data is current location data or historical retransmission data; Iterate through the serialized data to obtain the corrected timestamp, and compare the difference between the corrected timestamp and the current local clock time with ≤1s. If the difference is ≤1s, it is determined to be the current location data; otherwise, it is determined to be historical retransmission data.

[0065] S22: Add type marker; Add a type marker of RT-01 to the current location data and store it in the SBOX local DRAM cache (read / write speed ≥1GB / s), giving priority to occupying transmission resources; Add a type marker of HT-02 to the historical retransmission data; store the historical retransmission data in the local NAND Flash cache of SBOX according to the order of timestamps; The collected data will also be securely stored in DRA or NAND Flash according to its type to avoid data loss and prevent data loss due to unstable links, thus ensuring that all location information is traceable.

[0066] DRAM cache is dynamic random access memory used to temporarily store data at the current location that needs to be processed quickly.

[0067] NAND Flash cache is a non-volatile flash memory used as a large-capacity persistent cache to store historical data.

[0068] S23: Establish a categorized data index table; An index table is created for each of the categorized compressed data, and the index table records the storage address and transmission status, etc. The transmission status includes pending transmission, in transmission, and completed. This allows you to track the data transmission progress, quickly pinpoint specific data packets experiencing transmission delays or failures, and facilitates troubleshooting.

[0069] S3: Construct a real-time sub-channel for encrypted transmission of current location data; S31: Real-time monitoring of link status; The vehicle-mounted SBOX collects real-time link connection status, including parameters such as signal-to-noise ratio (SNR), bit error rate (BER), and remaining overhead time. SNR and BER parameters provide real-time feedback on link quality, supporting dynamic transmission strategies and preventing resource waste caused by transmitting at a fixed frequency when the link deteriorates. Monitoring remaining overhead time facilitates advance planning of transmission content, maximizing the utilization of satellite communication windows. Link quality grading thresholds are set to determine the link quality level. If SNR≥15dB, BER≤10 -4 Determined as a high-quality link; if 10dB≤SNR<15dB, 10 -4 <BER≤10 -3 If the link is classified as a normal link, and the SNR is less than 10 dB and the BER is greater than 10 dB, then it is considered a normal link. -3 It was determined to be a low-quality link.

[0070] S32: Encapsulates real-time data packets; A lightweight UDP-based transport protocol encapsulates current location data to generate real-time data packets. The real-time data includes a frame header, payload data, and a frame trailer.

[0071] The frame header includes the vehicle ID, data type identifier, payload length, and checksum, etc. The vehicle ID is identified by the vehicle ID hash value; The data type identifier is fixed as RT-01; The payload data is serialized current position data; The frame end includes the national cryptographic standard SM9 signature, etc.

[0072] S33: Encrypted using the national standard SM9 encryption; The SM9 identifier cipher algorithm is used to encrypt real-time data packets at the link layer. Each time a real-time data packet is sent, its payload data is updated to "transmitting" status in the index table. This ensures transmission security and prevents decryption or tampering.

[0073] S34: Dynamically transmit real-time data packets; If it is a high-quality link, send real-time data packets at a frequency of 10Hz. For ordinary links, the LZ77 compression algorithm is used to compress real-time data packets, and the compressed real-time data packets are sent at a frequency of 5Hz. If the link is of poor quality, compressed real-time data packets are sent at a frequency of 2Hz, and FEC erasure coding is used for transmission to improve the anti-interference capability of the transmission.

[0074] Based on the remaining overpass time, if the remaining overpass time is less than or equal to 3 seconds, only the real-time data packet with the latest timestamp will be transmitted.

[0075] Each real-time data packet has one retransmission opportunity, with a retransmission interval of 50ms.

[0076] Dynamic transmission ensures that the transmission process always provides the optimal real-time update rate under available conditions. It adopts a lightweight UDP-based protocol, which avoids the huge delays caused by repeated handshakes and congestion control misjudgments in Starlink, thus reducing transmission latency.

[0077] FEC erasure coding is an error control method that proactively adds redundant information before errors occur in data transmission, automatically detecting and correcting a certain number of errors. This invention only uses this technology and does not make any innovations, so the principle and process of the method will not be described in detail.

[0078] S35: Exception handling; If retransmission fails, the real-time data packet is marked as pending retransmission, and the pending real-time data packet is stored in the NAND Flash cache.

[0079] If the satellite connection is lost, transmission will be stopped immediately, and newly generated real-time data packets of the current location will be temporarily stored in the DRAM cache. Once the satellite reconnects, they will be transmitted with priority.

[0080] The retransmission mechanism improves the success rate of real-time data transmission, and the data to be retransmitted is stored in NAND Flash to avoid loss; when the satellite connection is lost, the data is temporarily stored and transmitted first after reconnection to ensure the continuity of real-time data.

[0081] S4: Establish a DTN retransmission channel for encrypted transmission of historical retransmission data; S41: Historical data retransmission is fragmented and packaged; The historical data is iterated through and divided into data shards of 100 records each, arranged chronologically. A unique shard identifier is generated, which includes the vehicle ID, start timestamp, end timestamp, and shard sequence number. Each data shard includes metadata such as the number of data records, shard sequence number, time range, and checksum.

[0082] S42: Encapsulate data fragments into data bundles; Data fragments are encapsulated into DTN Bundles according to the DTN protocol (RFC 5050). Each bundle includes metadata such as creation time, lifespan, source, and destination. The DTN protocol adapts to the intermittent connection characteristics of satellites, eliminating the need for continuous end-to-end connections and solving the transmission pain point of short overhead windows for low-Earth orbit satellites. The data bundle metadata facilitates routing management and improves transmission stability during multi-satellite handover.

[0083] Creation time is the timestamp of when the data bundle was first created and encapsulated; Time to live is the maximum duration for which a data bundle is allowed to remain in a network; The source is the network endpoint identifier that generates and first sends the data bundle; The destination is the network endpoint identifier to which the data bundle will ultimately be delivered; S43: End-to-end encryption is performed using the SM9 identifier cryptographic algorithm; To prevent data tampering and forgery, the source end uses the SM9 identifier cryptography algorithm to encrypt the data bundle and performs an SM9 signature on the data bundle. Each vehicle-mounted SBOX is pre-distributed with a private key bound to its unique identifier. The vehicle-mounted SBOX uses the destination end for encryption, ensuring that only the designated destination end can decrypt the data. With SM9 end-to-end encryption and signing, even if the data is stored and forwarded through multiple relay nodes, its content cannot be spied on or tampered with by intermediate nodes.

[0084] S44: Schedule the transmission of data bundles; The SBOX terminal monitors the overhead status of low-Earth orbit satellites in real time. When the remaining overhead time is ≥10 seconds, it initiates DTN retransmission to transmit data bundles. It updates the historical retransmission data within the data bundle in the index table to "transmitting in progress" and records the transmission progress. After each data bundle is transmitted, it waits for a response. If no response is received within 5 seconds, the data bundle is marked as pending retransmission. When the next satellite overhead occurs and DTN retransmission is initiated, it is prioritized for retransmission. If reception is successful, the historical retransmission data within the data bundle fragment is updated in the index table to "transmission completed." This efficiently utilizes fragmented connection time to transmit data bundles.

[0085] The transmission progress includes the number of bytes sent and the number of bytes remaining.

[0086] For data bundles that are not fully transmitted within the time it takes for a single satellite to pass overhead, the data bundles will continue to be transmitted when the next satellite passes overhead and DTN retransmission is initiated, based on the transmission progress, to ensure that the interrupted transmission is resumed.

[0087] This ensures that all historical trajectory data is delivered to the command platform in a complete and orderly manner, compensating for potential data loss in the real-time channel and providing a complete data chain for post-event review and task analysis.

[0088] S5: The platform receives data and stores it in categories; The platform receives real-time data packets and data bundles respectively, and after parsing and verification, stores them in the real-time database and the historical retransmission database respectively.

[0089] S51: Receive and store the current location data of real-time data packets; The platform uses a UDP port to receive real-time data packets. After parsing, SM9 decryption, and signature verification, it extracts the payload data. It obtains the vehicle ID and timestamp, deduplicates are removed based on the vehicle ID and timestamp, and duplicate real-time data packets are eliminated. The data type and checksum are verified. Upon successful verification, the current location data from the payload data is stored in the real-time database and sent to the WebSocket service in real time. This reduces platform reception latency, eliminates data redundancy caused by repeated transmissions during satellite handover, and saves database storage resources. The WebSocket service pushes data in real time, ensuring low latency for front-end visualization.

[0090] S52: Receive and store the historical retransmission data of the data bundle; The platform deploys DTN convergence nodes to receive data bundles, verify the integrity of data fragments, and obtain data fragments after SM9 decryption and signature verification. It then extracts historical retransmission data, deduplicates it based on fragment identifiers to avoid storing duplicate data from the same fragment, and sorts the extracted historical retransmission data by timestamp and stores it in the historical retransmission database. This improves the data bundle reception success rate; the fragment integrity verification and deduplication mechanism ensures accurate and non-duplicate storage of historical retransmission data; and the timestamp-based sorting facilitates rapid retrieval during trajectory playback, improving backtracking efficiency.

[0091] S6: Visual presentation; S61: Displays real-time location; The front-end obtains current location data via a WebSocket service and marks vehicle positions on an electronic map in real time based on this data. Hovering the mouse over a vehicle displays its ID, speed, and timestamp. This provides a clear view of the convoy's distribution, allowing command to quickly grasp the overall situation. Millisecond-level timestamps ensure the timeliness of location data, supporting precise tactical dispatching.

[0092] S62: Display the playback trajectory; S621: Data fusion and trajectory reconstruction; First, in response to the user's selection of vehicle ID and time range, the system obtains the current location data and historical retransmission data within the specified vehicle ID and time range from the real-time database and the historical retransmission database, and performs global sorting based on the timestamp. Then, the time difference between two adjacent data points in the global sort is checked. If the time difference is ≤1 second, it is considered normal data. If 1 second < time difference ≤ 8 seconds, linear interpolation is used to complete the missing data. The location of the missing point is calculated by linear interpolation based on the latitude and longitude of the two points and the time ratio, and marked as interpolated data. If 8 seconds < time difference ≤ 30 seconds, trajectory estimation is used to complete the data based on vehicle speed and heading angle. The speed and heading angle of the data point with the earlier timestamp are obtained. Assuming that the vehicle moves at a constant speed in a straight line during this time period, the position of each moment in the missing time period is estimated and marked as estimated data. If the time difference exceeds 30 seconds, no data is completed, and the period between two adjacent data points is marked as a disconnected time period.

[0093] Finally, the vehicle positions from the normal data, interpolated data, and extrapolated data are used to generate trajectory curves based on timestamps.

[0094] Filling in the data gaps caused by communication interruptions, the generated trajectory curves are continuous and reasonable, rather than fragmented point sets, ensuring the continuity of the trajectory curves and providing accurate and coherent situational information for command and decision-making.

[0095] S622: Render and display playback trajectory; The system renders and displays the trajectory curves, using different colors to represent normal data, interpolated data, and extrapolated data: normal data is rendered in blue, interpolated data in orange, and extrapolated data in red. Disconnection periods are connected by dashed lines. Different colors distinguish data types, allowing operators to quickly identify real, interpolated, and extrapolated data and avoid misjudgments; dashed lines mark disconnection periods, clearly presenting the communication status and aiding in link quality assessment.

[0096] S7: Regional Control; Users define electronic fences, set fence names and alarm rules. According to the alarm rules, the platform compares the vehicle's location with the electronic fence boundary in real time. If the vehicle's location exceeds the electronic fence boundary, an alarm is triggered, a pop-up notification and an audible alarm are pushed, and an alarm log is recorded.

[0097] The alarm log includes vehicle ID, time, fence name, etc.

[0098] Electronic fences are geometric areas that users can customize using a map interface, such as circles, polygons, and polylines.

[0099] Ensure timely detection of anomalies, and record alarms in logs to facilitate subsequent tracing and review, thereby simplifying fleet management.

[0100] The present invention has been described in the above-described embodiments; however, these embodiments are merely examples for implementing the present invention. It must be noted that the disclosed embodiments do not limit the scope of the present invention. Conversely, any modifications and refinements made without departing from the spirit and scope of the present invention are within the scope of patent protection of the present invention.

Claims

1. A method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets, characterized in that: Includes the following steps: S1: Collect and preprocess location data; The system collects location data and performs preprocessing on the location data, including timestamp alignment, outlier filtering, and unified coordinate system. The preprocessed data is then serialized to obtain serialized data. S2: Classify and label data types; Determine whether the serialized data is current location data or historical retransmission data, add type tags accordingly, and build a categorized data index table; S3: Construct a real-time sub-channel for encrypted transmission of current location data; The current location data is encapsulated to generate a real-time data packet, which is then encrypted using the national standard SM9. The link status is monitored in real time, the link quality level is determined, and the real-time data packet is dynamically transmitted based on the link quality level and the remaining overhead time of the low-Earth orbit satellite. S4: Establish a DTN retransmission channel for encrypted transmission of historical retransmission data; Historical data retransmission is fragmented and packaged to obtain data fragments. The data fragments are then encapsulated into data bundles and end-to-end encrypted using the SM9 identifier cryptography algorithm. The data bundles are then transmitted in conjunction with the low-Earth orbit satellite overhead status scheduling. S5: The platform receives data and stores it in categories; The platform receives real-time data packets and data bundles respectively, and after parsing and verifying them, stores them in the real-time database and the historical retransmission database respectively. S6: Visual presentation; Trajectory is reconstructed based on a hierarchical completion strategy to obtain different types of data, display real-time positioning and playback trajectory, and use differentiated rendering for different types of data; S7: Regional Control; Define multiple types of electronic fences, compare vehicle positions with fence boundaries in real time, and trigger alarms.

2. The method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets as described in claim 1, characterized in that: Step S1 includes: S11: Vehicle-mounted SBOX collects positioning data; The vehicle-mounted SBOX has a built-in GPS / BeiDou dual-mode positioning module. The dual-mode positioning module receives satellite signals in real time. When it captures signals from at least 4 satellites at the same time, it starts data acquisition and collects positioning data at a preset frequency. Otherwise, it attempts to reconnect at a frequency of 1 Hz and records the signal loss status. The collected positioning data is temporarily stored in the SBOX local cache and a directory is created according to the vehicle ID and the collection date. S12: Preprocessing positioning data; S121: Timestamp alignment; Correct the local RTC clock and unify the timestamp to UTC standard time; S122: Unified coordinate system; Set the coordinate system to the CGCS2000 standard coordinate system; S123: Outlier filtering; A preset jump detection threshold is set. The location data is compared with the jump detection threshold. If the jump detection threshold is exceeded, the location data is marked as abnormal and the location data marked as abnormal is filtered. S124: Serialization; The preprocessed data is serialized using the standard JSON format to obtain serialized data.

3. The method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets as described in claim 2, characterized in that: Location data includes vehicle position, speed, heading, and timestamp; vehicle position includes longitude, latitude, and altitude. The jump detection thresholds include the position jump threshold and the velocity jump threshold; Based on the vehicle location, compare the distance ∆d between adjacent timestamps of the vehicle location to see if it exceeds the location jump threshold. If it does, a location jump is determined and marked as abnormal; otherwise, it is normal. Based on vehicle speed, compare the absolute value of the difference between vehicle speeds at adjacent timestamps to see if it exceeds the speed jump threshold. If it does, it is determined to be a speed jump and marked as abnormal; otherwise, it is normal. The serialized data structure includes fields such as vehicle ID, corrected timestamp, CGCS2000 longitude, CGCS2000 latitude, altitude, driving speed, and heading angle.

4. The method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets as described in claim 1, characterized in that: Step S2 includes: S21: Determine whether the serialized data is current location data or historical retransmission data; Traverse the serialized data, obtain the corrected timestamp, and compare the difference between the corrected timestamp and the current local clock time with ≤1s; if the difference is ≤1s, it is determined to be the current location data; otherwise, it is determined to be the historical retransmission data. S22: Add type marker; Add a type marker of RT-01 to the current location data and store it in the SBOX local DRAM cache; Add a type marker of HT-02 to the historical retransmission data; store the historical retransmission data in the local NAND Flash cache of SBOX according to the order of timestamps; S23: Establish a categorized data index table; An index table is created for each of the categorized compressed data. The index table records the storage address and transmission status. The transmission status includes pending transmission, in transmission, and completed.

5. The method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets as described in claim 1, characterized in that: Step S3 includes: S31: Real-time monitoring of link status; The vehicle-mounted SBOX collects link connection status in real time, including signal-to-noise ratio, bit error rate, and remaining overhead time; it sets link quality grading thresholds to determine the link quality level as high-quality, normal, or poor-quality. S32: Encapsulates real-time data packets; A lightweight UDP-based transport protocol is used to encapsulate current location data and generate real-time data packets. S33: Encrypted using the national standard SM9 encryption; The SM9 identifier cipher algorithm is used to encrypt real-time data packets at the link layer. Each time a real-time data packet is sent, the payload data of the data packet is updated to the "transmitting" status in the index table. S34: Dynamically transmit real-time data packets; If it is a high-quality link, send real-time data packets at a frequency of 10Hz. For ordinary links, the LZ77 compression algorithm is used to compress real-time data packets, and the compressed real-time data packets are sent at a frequency of 5Hz. If the link is of poor quality, compressed real-time data packets are sent at a frequency of 2Hz and FEC erasure coding is used for transmission. Based on the remaining overpass time, if the remaining overpass time is less than or equal to 3 seconds, only the real-time data packet with the latest timestamp will be transmitted. Each real-time data packet has one retransmission opportunity, with a retransmission interval of 50ms; S35: Exception handling; If retransmission fails, the real-time data packet is marked as to be retransmitted, and the real-time data packet to be retransmitted is stored in the NAND Flash cache. If the satellite connection is lost, transmission will be stopped immediately, and newly generated real-time data packets of the current location will be temporarily stored in the DRAM cache. Once the satellite reconnects, they will be transmitted with priority.

6. The method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets as described in claim 1, characterized in that: Step S4 includes: S41: Historical data retransmission is fragmented and packaged; Traverse the historical data, divide it into data shards of 100 data entries according to time order, and generate a unique shard identifier; S42: Encapsulate data fragments into data bundles; Data fragments are encapsulated into data bundles according to the DTN protocol; each data bundle includes creation time, time to live, source, and destination. S43: End-to-end encryption is performed using the SM9 identifier cryptographic algorithm; S44: Schedule the transmission of data bundles; The SBOX terminal monitors the overhead status of low-Earth orbit satellites in real time. When the remaining overhead time is ≥10 seconds, it initiates DTN retransmission to transmit data bundles. It modifies the historical retransmission data within the data bundle in the index table to "transmitting". It also records the transmission progress. After each data bundle is transmitted, it waits for a receiving response. If no receiving response is received after 5 seconds, the data bundle is marked as pending retransmission. When the next satellite passes overhead and DTN retransmission is initiated, it is retransmitted first. If the reception is successful, the historical retransmission data within the data bundle fragment is updated in the index table to "transmission completed". For data bundles that are not fully transmitted within the time it takes for a single satellite to pass overhead, the data bundles will continue to be transmitted when the DTN retransmission is initiated for the next satellite to pass overhead, based on the transmission progress.

7. The method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets as described in claim 1, characterized in that: Step S5 includes: S51: Receive and store the current location data of real-time data packets; After receiving real-time data packets, parsing, decrypting with SM9, and verifying signatures, the payload data is extracted; the vehicle ID and timestamp are obtained, and duplicate real-time data packets are removed based on the vehicle ID and timestamp; the data type and check bit are verified; after the verification is passed, the current location data in the payload data is stored in the real-time database and sent to the WebSocket service in real time. S52: Receive and store the historical retransmission data of the data bundle; The platform deploys DTN convergence nodes to receive data bundles, verify the integrity of fragments, obtain data fragments after SM9 decryption and signature verification, extract historical retransmission data, deduplicate data according to fragment identifiers to avoid storing the same data fragment repeatedly, and sort the extracted historical retransmission data by timestamp and store it in the historical retransmission database.

8. The method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets as described in claim 1, characterized in that: Step S6 includes: S61: Displays real-time location; The front-end obtains the current location data through the WebSocket service, and marks the vehicle's location on the electronic map in real time based on the vehicle's location in the current location data. The vehicle ID, speed, and timestamp are displayed when the mouse hovers over the vehicle. S62: Display the playback trajectory; Data fusion is used to reconstruct the trajectory, obtain the trajectory curve, and the front end renders and displays the replay trajectory.

9. The method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets as described in claim 8, characterized in that: Step S62 includes: S621: Data fusion and trajectory reconstruction; First, in response to the user's selection of vehicle ID and time range, the system obtains the current location data and historical retransmission data within the specified vehicle ID and time range from the real-time database and the historical retransmission database, and performs global sorting based on the timestamp. Then, the time difference between two adjacent data in the global sort is checked. If the time difference is ≤1 second, it is considered normal data. If 1 second < time difference ≤8 seconds, linear interpolation is used to complete the missing data, and it is marked as interpolated data. If 8 seconds < time difference ≤30 seconds, the trajectory is calculated and completed based on vehicle speed and heading angle. The position of each moment within the missing time period is calculated and marked as calculated data. If the time difference exceeds 30 seconds, no completion is performed, and the period between two adjacent data is marked as a disconnected period. Finally, the vehicle positions from the normal data, interpolated data, and extrapolated data are used to generate trajectory curves based on timestamps; S622: Render and display playback trajectory; The rendering displays the trajectory curves, using different colors to represent normal data, interpolated data, and extrapolated data: normal data is rendered in blue, interpolated data in orange, and extrapolated data in red. Disconnected periods are connected by dashed lines.

10. The method for real-time display and control of low-orbit satellite communication vehicle positioning information for military and commercial vehicle fleets as described in claim 1, characterized in that: Electronic fences include circular, polygonal, and polyline geometric areas. Define the electronic fence, set the fence name and alarm rules. According to the alarm rules, the platform compares the vehicle position with the electronic fence boundary in real time. If the vehicle position exceeds the electronic fence boundary, an alarm is triggered, a pop-up notification and an audible alarm are pushed, and an alarm log is recorded. The alarm log includes the vehicle ID, time, and fence name.

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