Digital radar based transponder based shore based positioning and navigation system

Abstract

The present application relates to high-precision positioning technology field, specifically for the shore-based positioning and navigation system of transponder based on digital radar, the system comprises: pulse response acquisition module, time difference module, distance surface generation module, projection residual iteration module and navigation result output module.In the present application, the continuous time pairing sequence is constructed through the whole process of transmission, reception and response, the dispersed measurement is converted into the time domain chain which can be tracked, the target motion state has the ability of coherent expression, the adjacent propagation time difference and direction determination are combined, the dynamic change trend can be extracted, the influence of single point fluctuation is weakened, the abnormal node correction is realized through interval average and deviation identification, the distance distribution is more smooth and stable, the projection path is established combined with the azimuth angle, the positioning result gradually converges under the constraint of multiple time, the anti-interference ability and trajectory consistency are improved, the continuous navigation data frame is output, and the real-time and reliability in port monitoring and channel guidance are enhanced.

Description

Technical Field

[0001] This invention relates to the field of high-precision positioning technology, and in particular to a shore-based positioning and navigation system based on a digital radar transponder. Background Technology

[0002] High-precision positioning technology mainly involves a technical system that utilizes the propagation characteristics of electromagnetic waves to determine the location and spatial coordinates of targets. Its core aspects include the construction of ranging principles, signal transmission and echo reception, time delay calculation, multi-station collaborative measurement, and positioning solution methods. This involves transmitting specifically coded radio signals and receiving reflected or responding signals, combining propagation time difference or phase difference to calculate distance, and performing geometric positioning calculations based on known base station locations to determine the spatial location of the target. This technology is widely used in scenarios such as maritime navigation, traffic monitoring, and target tracking. Traditional radar transponder positioning systems refer to a positioning method that uses shore-based radar to transmit pulse signals, which are received by a transponder on the target and then delayed to transmit a response signal at a preset frequency. For shore-based distance and azimuth determination of water targets, shore-based radar transmits pulse signals with a fixed repetition frequency. After receiving the signal, the target transponder uses a frequency conversion circuit to convert the received signal to a preset response frequency and transmits the signal back through a transmission circuit. The shore-based system receives the response signal and calculates the distance based on the transmission and reception time interval, while simultaneously using antenna scanning to obtain target azimuth information, thus completing the positioning process.

[0003] Traditional shore-based radar transponder positioning relies heavily on the interval between single transmissions and responses to determine distance, focusing primarily on the validity of a single transmission and reception result. This approach neglects the value of continuous observation. When encountering conditions such as wave fluctuations, changes in ship attitude, or increased port clutter, abrupt jumps often occur between measurements. While operators can see the approximate location of the target, they struggle to accurately identify trajectory changes based on scattered data. Because the operation is biased towards instantaneous measurement, the range sequence lacks stable correlation constraints. Abnormal response delays, signal threshold fluctuations, or short-term instability in the receiving link can directly increase the current positioning error. If this error coincides with a ship approaching a dock, entering a narrow channel, or meeting another vessel, the displayed position may exhibit forward acceleration, backward dragging, or lateral deviation, affecting dispatching decisions. Traditional processing offers limited room for handling anomalies. When clutter echoes and valid responses are temporally adjacent, occasional anomalies can easily be mixed into the normal measurement sequence, exacerbating range fluctuations and resulting in a jagged screen trajectory. This makes it difficult for the monitoring end to distinguish between genuine maneuvers and measurement distortions. Coordinate calculations often rely solely on the current measurement relationship to directly provide position results, failing to adequately utilize the consistency between data from multiple time points. This leads to slight discrepancies in angles and distances during scanning, causing the position results to fluctuate repeatedly within a local area. Such shortcomings are more pronounced in areas with curved waterways in ports, bridge areas, and areas with strong water surface reflections. At best, this increases the burden of manual verification; at worst, it delays early warning opportunities and reduces the reliability of continuous monitoring and precise guidance of maritime targets. Summary of the Invention

[0004] To address the technical problems existing in the prior art, embodiments of the present invention provide a shore-based positioning and navigation system based on a digital radar transponder. The technical solution is as follows: On the one hand, a shore-based positioning and navigation system based on a digital radar transponder is provided, which includes: The pulse response acquisition module receives the pulse sequence output by the shore-based digital radar transmitter, the transmitted signal from the shore-based radar transmitting antenna, and the response signal returned by the shipborne transponder. Based on the preset response delay rule, it performs time correlation processing on the received signals, records the arrival time of the echo from the shore-based radar receiving antenna, pairs the transmission time and the arrival time of the echo, calculates the propagation time, and arranges them to form a response propagation time sequence. The time difference construction module receives the response propagation time sequence, calls the radar timing unit time reference signal, calculates the adjacent propagation time difference, determines the direction of change and calculates the distance increment, accumulates the distance increment to form a distance change trajectory and generates a continuous distance change sequence. The distance surface generation module receives the continuous distance change sequence, calls the shore-based navigation processing terminal cache unit to calculate the interval average to establish a reference sequence, determines the deviation and replaces abnormal nodes, and generates a continuous distance distribution sequence by mapping the time sequence. The projection residual iteration module receives the continuous distance distribution sequence and the angle sequence output by the shore-based radar azimuth scanning mechanism, performs coordinate transformation to form a projection path set, selects the median time coordinates to calculate the vertical distance to form a residual sequence, filters the residuals to determine the dominant direction and updates the coordinates, and repeats the calculation until the convergence criterion is met to generate the shore-based positioning coordinate result. The navigation result output module receives the shore-based positioning coordinates, calculates the distance and azimuth between the positioning coordinates and the shore-based radar installation point, encapsulates and writes them into the cache to generate a ship positioning and navigation data frame.

[0005] As a further embodiment of the present invention, the response propagation time sequence includes pulse number, round-trip delay value, and sequence time label; the continuous distance change sequence includes cumulative distance, change trend indicator, and trajectory stage marker; the continuous distance distribution sequence includes distribution node set, interval smoothing value, and continuity indicator; the shore-based positioning coordinate result includes shore-based lateral coordinate, shore-based longitudinal coordinate, and positioning information parameter; the ship positioning and navigation data frame includes coordinate field, distance field, and bearing field.

[0006] As a further aspect of the present invention, the process of calculating the adjacent propagation time difference includes selecting two consecutive propagation time values ​​in the response propagation time sequence according to the time order and performing differential operation, and limiting the absolute value of the adjacent propagation time difference to be within the range of zero to a preset upper limit time threshold; the preset upper limit time threshold is determined by the maximum ranging period corresponding to the time reference signal of the radar timing unit.

[0007] As a further aspect of the present invention, the process of determining the direction of change and calculating the distance increment includes comparing the adjacent propagation time difference with zero; a value greater than zero corresponds to the direction of increasing distance, and a value less than zero corresponds to the direction of decreasing distance.

[0008] As a further aspect of the present invention, the pulse response acquisition module includes: The pulse timing submodule acquires the pulse sequence output by the shore-based digital radar transmitter, records the transmission time corresponding to the pulse, acquires the transmission signal transmitted by the shore-based radar transmitting antenna and extracts the transmission mark, receives the response signal acquired by the shore-based radar receiving antenna and records the corresponding echo arrival time, performs time stamp merging on the transmission time and echo arrival time based on the same pulse mark, and organizes them according to the pulse order to generate a transmission and reception time group. The backhaul pairing submodule calls the transmit and receive time group, receives the echo arrival time recorded by the shore-based radar receiving antenna, establishes the time correlation between the transmit time and the echo arrival time based on the preset delay response rules of the shipborne transponder to the transmitted signal, performs pairing verification on the same pulse marker and establishes the sequential correlation, writes the transmit time and echo arrival time into the data structure, and obtains the time pairing table. The time delay sequence submodule, based on the time pairing table, performs time pairing and sequential arrangement of the transmission time and echo arrival time, calculates the corresponding propagation time value for the paired items, writes them into a continuous storage structure according to the pulse number order, and performs consistency verification on the number order and position relationship to generate the response propagation time sequence.

[0009] As a further aspect of the present invention, the time difference construction module includes: The differential generation submodule, based on the response propagation time sequence, calls the radar timing unit time reference signal to perform time difference calculation on adjacent propagation times, records the sequence position corresponding to the differential term and writes it into the sequential storage structure, performs sequence sorting on the differential result and maintains the position correspondence, and generates a time difference sequence. The direction increment submodule calls the time difference sequence, detects the time reference signal of the radar timing unit to form a reference time distance, performs change direction determination on the difference term, calculates the distance increment value based on the relationship between the direction mark and the time distance and writes it into the continuous record structure to obtain the distance increment sequence. The trajectory formation submodule performs continuous accumulation of distance increments based on the distance increment sequence and writes them into the trajectory record structure to form trajectory data. It then performs sequential organization of the trajectory data and verifies the sequence position correspondence to generate a continuous distance change sequence.

[0010] As a further aspect of the present invention, the distance surface generation module includes: The mean parameter building submodule reads the distance increment data by calling the shore-based navigation processing terminal cache unit according to the continuous distance change sequence, detects the interval division position and writes it into the cache structure, performs interval average calculation on the data in the interval, writes it into the reference record area in time order and maintains the sequence correspondence, and generates the interval reference sequence. The deviation replacement submodule calls the interval reference sequence, collects the distance increment corresponding to the continuous distance change sequence, performs deviation judgment on the data item and the reference record, reads the deviation out-of-bounds position and performs replacement processing, and writes the corrected data into the storage structure in the original order to obtain the corrected distance sequence. The mapping submodule obtains the time stamp corresponding to the data item based on the corrected distance sequence, performs mapping processing on the time sequence and writes it into a continuous distribution structure, maintains the correspondence between the sequence position and time, organizes the mapping result into continuously arranged data, and generates a distance continuous distribution sequence.

[0011] As a further aspect of the present invention, the projection residual iteration module includes: The projection conversion submodule obtains the distance value and azimuth angle corresponding to the time sequence position based on the continuous distance distribution sequence and the angle sequence output by the shore-based radar azimuth scanning mechanism. It performs coordinate transformation on the same time sequence position and writes it into the path record structure, maintaining the correspondence between time order and position. The conversion results are organized into set data according to the scanning order to generate a set of projection paths. The residual orientation submodule calls the projection path set, selects the median time coordinate as the current coordinate, performs vertical distance calculation between the current coordinate and the path and writes it into the residual record structure, forms a residual sequence according to the path order, performs filtering and judgment on the residual distribution and extracts the direction mark to obtain the dominant direction mark. The iterative convergence submodule updates the current coordinates based on the dominant direction marker and the projection path set, repeatedly performs vertical distance calculation on the updated coordinates and records the residual changes, detects the correspondence between the residual changes and the convergence judgment conditions, stops the coordinate update and writes it into the positioning record structure, and generates the shore-based positioning coordinate results.

[0012] As a further aspect of the present invention, the navigation result output module includes: The coordinate calculation submodule calls the shore-based positioning coordinate results to obtain the shore-based radar installation point coordinate data, performs distance calculation on the positioning coordinates and installation point coordinates and writes them into the record structure, organizes the time-series position data in chronological order and maintains the sequence correspondence, and generates a positioning distance sequence. The azimuth generation submodule obtains the location data corresponding to the shore-based positioning coordinates based on the positioning distance sequence, calls the coordinates of the shore-based radar installation point to perform azimuth angle calculation and writes it into the record structure, organizes the azimuth data in chronological order and establishes a correspondence with the distance sequence to obtain the azimuth angle sequence. The encapsulation output submodule, based on the azimuth sequence and the positioning distance sequence, calls the interface unit of the port shore-based navigation display terminal and the waterway vessel monitoring system to perform data encapsulation and write it into the cache structure in chronological order, maintain the consistency of the data item order, establish a data frame structure, and generate a vessel positioning and navigation data frame.

[0013] As a further aspect of the present invention, the process of forming a distance change trajectory by accumulating the distance increment value point by point in chronological order, and limiting the change amplitude of a single accumulation result to not exceed a preset distance change threshold, and the distance increment value exceeding the preset distance change threshold is truncated before participating in the accumulation to generate the continuous distance change sequence.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are as follows: In this invention, a continuous time pairing sequence is constructed through the entire process of transmission, reception, and response, transforming dispersed measurements into a traceable time-domain chain. This enables the target's motion state to have a coherent expression capability. By combining the difference in adjacent propagation durations and direction determination, dynamic change trends can be extracted, reducing the impact of single-point fluctuations. Abnormal node correction is achieved through interval averaging and deviation identification, making the distance distribution smoother and more stable. Furthermore, by combining the azimuth angle to establish a projection path, the positioning results gradually converge under multi-time constraints, improving anti-interference capability and trajectory consistency. Continuous navigation data frames are output, enhancing the real-time performance and reliability in port monitoring and waterway guidance. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a system flowchart of the present invention; Figure 2 This is a system block diagram of the present invention; Figure 3 This is a flowchart of the pulse response acquisition module in this invention; Figure 4 This is a flowchart of the time difference construction module in this invention; Figure 5 This is a flowchart of the distance surface generation module in this invention; Figure 6 This is a flowchart of the projection residual iteration module in this invention; Figure 7 This is a flowchart of the navigation result output module in this invention. Detailed Implementation

[0017] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0018] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0019] This invention provides a shore-based positioning and navigation system based on a digital radar transponder, such as... Figure 1-2 The diagram shows a shore-based positioning and navigation system based on a digital radar transponder. The system includes: The pulse response acquisition module acquires the pulse sequence and corresponding transmission time output by the shore-based digital radar transmitter, receives the arrival time of the echo response signal acquired by the shore-based radar receiving antenna, and acquires the response signal corresponding to the pulse based on the trigger response mechanism of the shipborne transponder based on the transmission signal. The transmission time and the corresponding echo arrival time are time-paired and arranged in order, and the propagation time is calculated on the paired data to form a continuously arranged response propagation time sequence. The time difference construction module is based on the response propagation time series. It calls the radar timing unit time reference signal to perform time difference calculation on adjacent propagation times and form a time difference sequence. It performs change direction determination on the time difference sequence and completes range increment calculation. It performs continuous accumulation on the range increment and forms a range change trajectory, generating a continuous range change sequence. The distance surface generation module calls the shore-based navigation processing terminal cache unit to perform interval averaging calculation on the distance increment and establish a reference sequence based on the continuous distance change sequence. It then performs deviation judgment on the distance increment and reference sequence and completes the replacement of abnormal nodes. Finally, it performs time sequence mapping on the processed distance data and forms a continuous distribution relationship, generating a continuous distance distribution sequence. The projection residual iteration module is based on the continuous distribution sequence of distance and the angle sequence output by the shore-based radar azimuth scanning mechanism. It performs coordinate transformation on the distance value and azimuth angle to form a set of projection paths, selects the median coordinate of time as the current coordinate, performs vertical distance calculation on the current coordinate and the projection path to form a residual sequence, performs filtering on the residual sequence to determine the dominant direction, performs direction update on the current coordinate and repeats the residual calculation and change judgment. When the residual change meets the convergence judgment condition, the update stops and the shore-based positioning coordinate result is generated. The navigation result output module calls the shore-based positioning coordinate results, combines the port shore-based navigation display terminal and the waterway vessel monitoring system interface unit to perform distance and azimuth calculations between the coordinates and the shore-based radar installation point, and performs data encapsulation and cache writing in chronological order to generate a vessel positioning and navigation data frame.

[0020] The response propagation time series includes pulse number, round-trip delay value, and sequence time label; the continuous distance change series includes cumulative distance, change trend indicator, and trajectory stage marker; the continuous distance distribution series includes distribution node set, interval smoothing value, and continuity indicator; the shore-based positioning coordinate results include shore-based lateral coordinates, shore-based longitudinal coordinates, and positioning information parameters; the ship positioning and navigation data frame includes coordinate field, distance field, and bearing field.

[0021] Specifically, such as Figure 2 , 3 As shown, the pulse response acquisition module includes: The pulse timing submodule acquires the pulse sequence output by the shore-based digital radar transmitter, records the transmission time corresponding to the pulse, acquires the transmission signal transmitted by the shore-based radar transmitting antenna and extracts the transmission mark, receives the response signal acquired by the shore-based radar receiving antenna and records the corresponding echo arrival time, performs time stamp merging on the transmission time and echo arrival time based on the same pulse mark, and organizes them according to the pulse order to generate a transmission and reception time group. The output of the shore-based digital radar transmitter continuously reads the pulse sequence, writing the arrival time of each pulse's leading edge at the counting gate into the timing buffer. The transmitted signal obtained from the shore-based radar's transmitting antenna coupling end is then sent to the threshold shaping circuit to extract the transmission marker synchronized with that pulse. The shipborne transponder receiving unit synchronously records the arrival time of the trigger edge and deletes isolated spikes below the noise floor in the receiving channel. The deletion rule selects records with a continuous width less than 0.2 microseconds and an amplitude less than 20% of the main pulse's peak value. Subsequently, time-stamped merging is performed according to the pulse number. During merging, a pairing rule is used where adjacent numbers differ by 1 and the time difference falls within the range of 1.15 milliseconds to 1.25 milliseconds. Records outside this range are transferred to the inspection queue. Taking one set of measured data as an example, the five consecutive transmission times are 100.000 ms, 101.190 ms, 102.381 ms, 103.571 ms, and 104.761 ms, respectively, and the shipborne transponder reception times are 100.086 ms, 101.276 ms, 102.467 ms, 103.657 ms, and 104.847 ms, respectively. After merging, five sets of transmission and reception times are formed. The pulse repetition period used in this submodule is set to approximately 1 millisecond, following the common repetitive transmission pattern of marine pulse radar, and the pulse width is on the order of 0.8 microseconds, to ensure consistency with actual shore-based navigation radar.

[0022] Table 1. Pulse timing and pairing raw data table

[0023] As shown in Table 1, the transmission time, shipborne reception time, shipborne transmission time, and shore-based echo arrival time are arranged in the same numbered order, providing direct input for subsequent time pairing, propagation time calculation, and differential construction.

[0024] The backhaul pairing submodule calls the transmit and receive time group, receives the echo arrival time recorded by the shore-based radar receiving antenna, establishes the time correlation between the transmit time and the echo arrival time based on the shipborne transponder's preset delay response rules for the transmitted signal, performs pairing verification on the same pulse marker and establishes a sequential correlation, writes the transmit time and echo arrival time into the data structure, and obtains the time pairing table. After reading the transmit and receive time group, the delay rule record of the shipborne transponder transmitting unit is called, and the corresponding echo time for each pulse is retrieved item by item. The arrival time of the echo detected by the shore-based radar receiving antenna is sent to the verification area with the same number. During verification, it is first checked whether the delay between the transmit time and the echo time falls within the preset echo window. In this embodiment, the lower limit of the window is 35 microseconds and the upper limit is 45 microseconds. This range was obtained through three sets of shore-based joint debugging tests. If it is below 35 microseconds, the transmit shaping is insufficient, and if it is above 45 microseconds, the time isolation with adjacent pulses is weakened. Then, it is checked whether the difference between the echo time and the echo arrival time is no more than 2 microseconds from the difference between the transmit time and the shipborne receiving time. If it meets the requirement, the four times are written into the time pairing table. Taking the data in Group 1 of Table 1 as an example, the shipborne transmission time is 100.126 milliseconds, which is 126 microseconds later than the transmission time. After deducting the 86 microseconds of outbound propagation, the inherent delay is 40 microseconds, which is within the window. The shore-based echo arrival time is 100.212 milliseconds, which is 86 microseconds later than the transmission time, consistent with the outbound propagation difference. Therefore, the sequence association is completed. The response delay value used in this submodule is set in light of the fact that there are individual differences in existing transponder models. During the joint debugging phase, 38 microseconds, 40 microseconds, and 42 microseconds were verified respectively. At 40 microseconds, there were no mis-order pairings for 20 consecutive rounds.

[0025] The time delay sequence submodule is based on the time pairing table. It performs time pairing and arranges the transmission time and echo arrival time in order. It calculates the corresponding propagation time value for the paired items, writes them into the continuous storage structure according to the pulse number order, and performs consistency check on the number order and position relationship to generate the response propagation time sequence. The transmission time and echo arrival time are extracted row by row from the time pairing table. Time pairings are established according to pulse number order. Then, the difference between the transmission time and the corresponding echo arrival time of each pairing is calculated to obtain the single-pulse response propagation time value. Before writing to the continuous storage structure, it is checked whether the number sequence is increasing and whether the storage position is continuous. If there is a number jump, the two items before and after the position are copied to the verification area for re-comparison. In the embodiment, the first item, the echo arrival time of 100.212 milliseconds, is subtracted from the transmission time of 100.000 milliseconds to obtain 212 microseconds; the second item is 211 microseconds; the third item is 212 microseconds; the fourth item is 212 microseconds; and the fifth item is 212 microseconds. The maximum fluctuation of a single item in this sequence is 1 microsecond, which is lower than the preset consistency threshold of 3 microseconds. Therefore, the entire column is written into the response propagation time sequence. The threshold of 3 microseconds was verified using 10 sets of port trial data. When the threshold is compressed to 2 microseconds, an additional 7% of valid pulses will be discarded due to reception threshold jitter. When relaxed to 4 microseconds, two sets of anomalous items affected by sidelobe interference will be included in the sequence. This submodule maintains a propagation time on the order of 212 microseconds as the subsequent differential input. This order of magnitude is consistent with the common ranging principle of radar that uses the round-trip time from transmission to echo to determine the distance. During nautical chart verification, the corresponding target distance is on the order of tens of kilometers.

[0026] Specifically, such as Figure 2 , 4 As shown, the time difference construction module includes: The differential generation submodule is based on the response propagation time series. It calls the radar timing unit time reference signal to perform time difference calculation on adjacent propagation times, records the sequence position corresponding to the differential term and writes it into the sequential storage structure, performs sequence sorting on the differential result and maintains the position correspondence, and generates a time difference sequence. After reading the response propagation time sequence, the time reference signal output by the radar timing unit is used as the item-by-item alignment reference. Differential operations are performed on two adjacent propagation time values, and the difference result, along with its sequence position, is written into the sequential storage structure. In actual processing, a missing item scan is first performed on the propagation time sequence. If the difference in number between two consecutive items is greater than 1, the difference position is marked as invalid and does not proceed to subsequent incremental operations. In this embodiment, the response propagation time sequence is 212 microseconds, 211 microseconds, 212 microseconds, 212 microseconds, and 212 microseconds respectively. After adjacent differential operations, the second position is -1 microsecond, the third position is +1 microsecond, the fourth position is 0 microsecond, and the fifth position is 0 microsecond. To prevent clock edge jitter amplification, the submodule performs a double-adjacent value check before writing. The rule is that if the absolute value of the current difference value is greater than twice the average absolute value of the two consecutive items, it is entered as an abnormal bit. In this example, all four difference values ​​pass the check. During sequence rearrangement, the numbering of positions 2 to 5 remains unchanged, and invalid bits are recorded separately as placeholders. The original timing sequence can still be restored based on this for subsequent direction determination. The time difference sequence obtained by this submodule directly reflects the changing rhythm of the round-trip propagation time of adjacent pulses, establishing a continuous input chain for subsequent distance increment calculation.

[0027] The direction increment submodule calls the time difference sequence, detects the time reference signal of the radar timing unit to form a reference time distance, performs change direction determination on the difference term, calculates the distance increment value based on the relationship between the direction mark and the time distance, and writes it into the continuous record structure to obtain the distance increment sequence; The baseline time interval is 1.190 milliseconds, obtained by averaging the intervals between the previous five transmission times. Then, direction determination is performed on each differential term within the submodule: a positive differential value is marked as moving away, a negative differential value as moving closer, and an absolute differential value below 0.5 microseconds is marked as translation. During quantization, the propagation time change corresponding to each differential term is converted into a distance increment, based on the round-trip propagation relationship of electromagnetic waves. For example, a negative 1 microsecond at position 2 results in a distance increment of approximately -150 meters; a positive 1 microsecond at position 3 results in approximately +150 meters; and positions 4 and 5 both result in 0 meters. To prevent isolated large jumps, this submodule sets a distance increment limit threshold of 220 meters. This value is calculated by combining the common speed range in the port area with the 1.190 millisecond time interval and then verified through eight sets of sea trials. A threshold below 180 meters will cut off the effective changes of high-speed vessels entering the port, and a threshold above 260 meters will trigger a multipath anomaly. In this example, all parameters are within the amplitude limit range, so the range increment sequence is written in the original order. The marine radar repetitive transmission rhythm and round-trip ranging relationship used in this submodule are consistent with the existing marine pulse radar navigation principle.

[0028] The trajectory formation submodule continuously accumulates the distance increments according to the distance increment sequence and writes them into the trajectory record structure to form trajectory data. It then sorts the trajectory data in order and verifies the sequence position correspondence to generate a continuous distance change sequence. After reading the distance increment sequence, the reference distance before the first valid position is used as the starting value. In this example, the reference distance is 31.800 kilometers, which is converted from the first propagation time of 212 microseconds. Then, continuous accumulation is performed sequentially along the positions, adding each distance increment to the distance result of the previous position and writing it into the trajectory record structure. Based on the data in Table 1, the second position, after substituting the aforementioned 31.800 kilometers and adding -150 meters, yields 31.650 kilometers. The third position, after adding +150 meters, yields 31.800 kilometers. The fourth and fifth positions remain at 31.800 kilometers. After writing, the sequence is sorted, and the position numbers are checked to ensure a one-to-one correspondence with the trajectory record line numbers. If misalignment occurs, the sequence is reordered using time stamps. This submodule sets a trajectory jump point detection threshold of 300 meters. The setting process uses 12 sets of test flight track data for tiered comparison. A 200-meter threshold would misidentify normal turning points as jump points, a 350-meter threshold would miss false peaks affected by shoreline reflections, and the 300-meter threshold has the lowest false deletion and false detection rates. In this example, the adjacent changes in the continuous distance change sequence are only 150 meters and 0 meters, so all positions are retained. This continuous distance change sequence will be directly used as a reference value for establishing interval averages and as the original input when replacing the out-of-bounds deviation term later. Table 2 Parameter Thresholds and Validation Results

[0029] As shown in Table 2, each threshold value was determined after interval testing, and all subsequent sub-modules referenced the same set of implementation parameters to ensure consistency of the context data chain.

[0030] Specifically, such as Figure 2 , 5 As shown, the distance surface generation module includes: The mean parameter building submodule reads the distance increment data from the shore-based navigation processing terminal cache unit based on the continuous distance change sequence, detects the interval division position and writes it into the cache structure, performs interval average calculation on the data within the interval, writes it into the reference record area in chronological order and maintains the sequence correspondence, and generates the interval reference sequence. The distance values ​​at each location are read from the continuous distance change sequence, and then the distance increment records stored in the buffer unit of the shore-based navigation processing terminal are called to divide the interval. The interval length is set according to 10 pulse positions. When there are fewer than 10 samples in the port area test, the length of the current complete sample is used. In this embodiment, for illustrative purposes, 5 positions are used to form one interval, and the distance values ​​within the interval are 31.800 km, 31.650 km, 31.800 km, 31.800 km, and 31.800 km, respectively. The submodule first writes the interval boundary index into the buffer structure, and then performs an average calculation on the data within the interval to obtain the interval reference value of 31.770 km. Subsequently, the reference value is written into the reference record area in chronological order. Positions 1 to 5 are all associated with the same reference value, and the original distance values ​​of each position are retained for deviation determination. To avoid the reference value being affected by momentary jitter due to excessively short intervals, the submodule compared the lengths of 5-, 8-, and 10-item intervals during integration testing. The 5-item interval can completely cover one response round within a short flight segment, and the resulting reference value deviates from the manually verified distance by 42 meters. The 8-item interval has a deviation of 61 meters, and the 10-item interval has a deviation of 89 meters. Therefore, this embodiment uses the 5-item interval. The interval reference sequence output by this submodule does not change the original position order; it only adds a reference record field at each position for subsequent deviation replacement submodules to call item by item.

[0031] The deviation replacement submodule calls the interval reference sequence, collects the distance increment corresponding to the continuous distance change sequence, performs deviation judgment on the data items and the reference record, reads the deviation out-of-bounds position and performs replacement processing, and writes the corrected data into the storage structure in the original order to obtain the corrected distance sequence. The reference value for the interval is 31.770 km, with deviations of 30 m, 120 m, 30 m, 30 m, and 30 m at each location. The deviation replacement threshold is set to 150 m based on Table 2. The setting process utilizes six actual measurements at the shore port, using 120 m, 150 m, and 180 m as the cutoff lines. At 150 m, the corrected mean square deviation is the lowest, and normal minor port arrival and departure fluctuations are not overwritten as the reference value. In this example, location 2 has a deviation of 120 m, which is within the boundary, so the original value is retained. If a location shows a deviation of 31.980 km, the deviation reaches 210 m, and the submodule will replace that location with the reference value of 31.770 km, recording the reason for the replacement in the correction marker. To avoid continuous replacements forming a flat-top trajectory, the submodule adds an adjacent protection rule: when two or more consecutive locations simultaneously exceed the boundary, only the middle location is replaced, while the first and last locations are retained for subsequent projection residual verification. After processing in this example, the corrected distance sequence remains 31.800 km, 31.650 km, 31.800 km, 31.800 km, and 31.800 km. The advantage of this submodule is that it corrects isolated outliers before they enter spatial mapping by using interval reference values ​​and deviation thresholds together in the determination.

[0032] The mapping to sequence submodule is based on the modified distance sequence. It obtains the time stamp corresponding to the data item, performs mapping processing on the time order and writes it into a continuous distribution structure, maintains the correspondence between the sequence position and time, and organizes the mapping result into continuously arranged data to generate a distance continuous distribution sequence. The time stamps at positions 1 to 5 respectively inherit the aforementioned launch times of 100.000 ms, 101.190 ms, 102.381 ms, 103.571 ms, and 104.761 ms. During mapping, each time stamp is combined with its corresponding corrected distance into a continuous record. If a time stamp is found to be not increasing compared to the previous one, the correct position is first filled in according to the original launch number, and then written into the distribution structure. In this example, the five time stamps are strictly increasing, so the data is directly arranged continuously, recorded as 100.000 ms corresponding to 31.800 km, 101.190 ms corresponding to 31.650 km, 102.381 ms corresponding to 31.800 km, 103.571 ms corresponding to 31.800 km, and 104.761 ms corresponding to 31.800 km. This submodule also has a time mapping tolerance of 20 microseconds to identify duplicate writes caused by cache refresh. The tolerance value is obtained through clock synchronization testing. When the tolerance is compressed to 10 microseconds, the same sampling event will be mistakenly split; when it is relaxed to 30 microseconds, adjacent pulses will be merged. After the continuous distribution sequence is formed, no distance correction is performed; only the one-to-one correspondence between time position and distance position is maintained, providing a direct retrieval entry point for obtaining distance values ​​and azimuth angles at the same time sequence position during projection transformation.

[0033] Specifically, such as Figure 2 , 6 As shown, the projection residual iteration module includes: The projection conversion submodule obtains the distance value and azimuth angle corresponding to the time sequence position based on the continuous distribution sequence of distance and the angle sequence output by the shore-based radar azimuth scanning mechanism. It performs coordinate transformation on the same time sequence position and writes it into the path record structure, maintaining the correspondence between time order and position. The conversion results are organized into set data according to the scanning order to generate a set of projection paths. The system reads the continuous distance distribution sequence and obtains the angle sequence corresponding to the same time-series position from the shore-based radar azimuth scanning mechanism. Then, the distance value and azimuth angle of the same position are written into the coordinate transformation queue. In this embodiment, the azimuth angles of the five positions are taken as 42.0 degrees, 42.5 degrees, 43.0 degrees, 43.5 degrees, and 44.0 degrees respectively, and the distance values ​​are substituted into the aforementioned corrected distance sequence. During the transformation, the shore-based radar installation point is used as the origin, and the distance value of each position is decomposed into eastward and northward components along the corresponding azimuth. The decomposition results are written into the path recording structure, while maintaining the scanning order. Taking 31.800 km and 42.0 degrees as examples, the eastward coordinates are approximately 21.280 km and the northward coordinates are approximately 23.630 km; 31.650 km and 42.5 degrees correspond to approximately 21.380 km eastward and approximately 23.330 km northward. The remaining three positions sequentially form a set of continuous projection paths. Marine shore-based navigation radars commonly employ continuously rotating antennas for azimuth scanning. Commercial marine radars offer rotation rates of 24, 36, 48, and 60 revolutions per minute. This embodiment uses a 36-revolution-per-minute sampling rate to stabilize adjacent angle steps within the 0.5 metric level. After the aggregated data output by this submodule is solidified according to the scanning sequence, the residual orientation submodule can directly calculate the vertical distance from the current coordinates to each path based on this data.

[0034] The residual orientation submodule calls the projection path set, selects the median time coordinate as the current coordinate, performs vertical distance calculation between the current coordinate and the path and writes it into the residual record structure, forms a residual sequence according to the path order, performs filtering and judgment on the residual distribution and extracts the direction mark to obtain the dominant direction mark. After calling the projection path set, the median position is selected as the initial value of the current coordinates in chronological order. In this embodiment, the third projection point is selected, with coordinates of approximately 21.690 km and 23.240 km. Then, the perpendicular distance between the current coordinates and the remaining paths is calculated and written into the residual record structure in path order. During the calculation, the shortest distance from the current coordinates to the straight line of the target path is taken item by item. The residual for the first path is 36.2 meters, the residual for the second path is 18.5 meters, the residual for the third path is 0 meters, the residual for the fourth path is 21.4 meters, and the residual for the fifth path is 44.8 meters. The residual distribution is filtered using a dominant direction determination rule, which compares the cumulative difference between the residuals of the paths on both sides of the current coordinates. If the cumulative value of the latter path is more than 20 meters greater than the cumulative value of the former path, it is marked as a forward adjustment; otherwise, it is marked as a backward adjustment. The 20-meter threshold was determined by 10 sets of near-shore trajectory tests at the wharf. At 15 meters, the number of direction reversals is too high, and at 25 meters, the initial convergence is too slow. In this example, the cumulative value on the rear side is 66.2 meters, and the cumulative value on the front side is 54.7 meters, with a difference of 11.5 meters, which does not exceed 20 meters. Therefore, it is recorded first to maintain the direction, and then checked in conjunction with the results of the next round of updates. This submodule outputs the dominant direction marker together with the complete residual sequence without modifying the original path set field, so that the iterative convergence submodule can continue to call it.

[0035] The iterative convergence submodule updates the current coordinates based on the dominant direction marker and the set of projection paths. It repeatedly performs vertical distance calculation on the updated coordinates and records the residual changes. It detects the correspondence between the residual changes and the convergence judgment conditions, stops the coordinate update, writes the coordinates into the positioning record structure, and generates the shore-based positioning coordinate results. The current coordinates are updated based on the dominant direction marker and the projection path set. During the update, the movement follows the average direction of the current azimuth angle, with the single-round movement distance set to 50% of the average residual of the previous round. In this embodiment, the average residual of the first round is 24.18 meters, so the movement step size is 12.09 meters. Since the previous submodule provides a direction to maintain, the submodule uses bidirectional probing, updating once forward and once backward, recalculating the residuals, and selecting the side with the smaller total residual. The calculation results show that after updating forward, the total residual decreases to 98.4 meters, and after updating backward, the total residual decreases to 86.1 meters. Therefore, the backward coordinate update is adopted. In the second round, the update is again based on 50% of the average residual, with the step size reduced to 8.61 meters, and the total residual decreases to 74.3 meters. In the third round, the step size is 7.43 meters, and the total residual decreases to 72.0 meters. In the fourth round, the step size is 7.20 meters, and the total residual changes by only 0.9 meters. The convergence stopping threshold is set to 1.2 meters according to Table 2. Coordinate updates terminate when the total residual change between the previous two rounds is less than 1.2 meters. In this example, the fourth round meets the condition, so the updated coordinates are written into the positioning record structure, resulting in shore-based positioning coordinates of approximately 21.642 km and 23.198 km. The advantage of this submodule is that by using the residual change value and the convergence stopping threshold together in iterative control, the positioning record is stably settled within a finite number of rounds, no longer subject to the influence of local path noise.

[0036] Specifically, such as Figure 2 , 7 As shown, the navigation result output module includes: The coordinate calculation submodule calls the shore-based positioning coordinate results, obtains the shore-based radar installation point coordinate data, performs distance calculation on the positioning coordinates and installation point coordinates and writes them into the record structure, organizes the time-series position data in chronological order and maintains the sequence correspondence, and generates a positioning distance sequence. The installation point coordinates are set to 0 km and 0 km. Distance calculations are performed on the positioning coordinates and installation point coordinates, and the calculation results are written into the record structure in chronological order. In this embodiment, the positioning coordinates are approximately 21.642 km and 23.198 km, which translates to a positioning distance of approximately 31.730 km. To reflect the temporal positional relationship, the submodule also attaches this positioning distance to the last record of the aforementioned five time markers, forming a position time item. If the deployment scenario is continuous navigation, the submodule repeats the same calculation for each convergence result and sorts them in the sequence table by millisecond timescale. Compared with the last record of the aforementioned corrected distance sequence, 31.800 km, the positioning distance differs by approximately 70 meters, falling within the allowable deviation zone of 100 meters for shore-based positioning in the port area. Therefore, this positioning result is deemed valid. This allowable deviation zone was set by the joint shore-port test, which used 80 meters, 100 meters, and 120 meters for comparison. The efficiency and stability rate were highest at 100 meters. After this submodule is completed, the positioning distance sequence retains both the geometric distance and the corresponding temporal position, providing a common timescale for the next submodule to generate the azimuth sequence.

[0037] The azimuth generation submodule obtains the location data corresponding to the shore-based positioning coordinates based on the positioning distance sequence, calls the coordinates of the shore-based radar installation point to perform azimuth angle calculation and writes it into the record structure, organizes the azimuth data in chronological order and establishes a correspondence with the distance sequence to obtain the azimuth angle sequence. The positioning coordinates are 21.642 km and 23.198 km, and the installation point coordinates are 0 km and 0 km, which translates to an azimuth of approximately 43.0 degrees. The submodule writes 43.0 degrees into the azimuth record structure and combines it with the 31.730 km positioning distance to form the same navigation record. To prevent azimuth jumps, the submodule sets an adjacent azimuth difference check threshold of 1.5 degrees. If the azimuth difference between two consecutive positioning results exceeds 1.5 degrees, the median of the previous three records is retrieved for verification. In this example, the azimuth of the aforementioned projected path gradually increases from 42.0 degrees to 44.0 degrees, with 43.0 degrees being the median of the sequence and not triggering verification. This threshold value was derived from seven sets of inbound and outbound trajectory tests. A threshold of 1.0 degrees triggers too many verifications during the turning and berthing phases, while a threshold of 2.0 degrees will overlook local abnormal swings. After this processing is completed, the azimuth sequence and the positioning distance sequence have formed a two-field result under the same time frame. In subsequent encapsulation, there is no need to rebuild the corresponding relationship again. You can simply take the data directly according to the existing row number. Table 3 Comparison of Navigation Outputs

[0038] As shown in Table 3, the complete solution in this embodiment is superior to the control solution in terms of distance error, azimuth error and effectiveness. The average distance error is reduced from 118 meters to 58 meters, a reduction of about 50.8%, and the average azimuth error is reduced from 1.82 degrees to 0.74 degrees. This shows that the aforementioned linkage data chain of interval reference, deviation replacement and residual iteration can be applied to verifiable navigation output results.

[0039] The encapsulation and output submodule, based on the azimuth sequence and positioning distance sequence, calls the interface unit of the port shore-based navigation display terminal and the waterway vessel monitoring system, performs data encapsulation in chronological order and writes it into the cache structure, maintains the consistency of the data item order and establishes a data frame structure, and generates a vessel positioning and navigation data frame. After calling the azimuth sequence and positioning distance sequence, the time stamp, positioning distance, azimuth, and positioning validity flag under the same time sequence are written into the cache structure. Then, a data frame with a fixed field order is established according to the requirements of the waterway vessel monitoring system interface. In the embodiment, the last navigation record is written with 104.761 milliseconds, 31.730 kilometers, 43.0 degrees, and a validity flag of 1. During encapsulation, the frame header is written first, followed by the time field, distance field, azimuth field, and status field, and finally the verification field. The fields use a fixed-length text format, with the distance retained to 0.001 kilometers and the azimuth retained to 0.1 degrees. If multiple navigation records are generated within the same cache period, they are written sequentially in ascending order of the time stamp, and insertion or supplementary writing is prohibited, thus maintaining consistency with the line numbers of the aforementioned sub-modules. Before output, an intra-frame consistency check is performed, comparing the row numbers of the positioning distance sequence and the azimuth sequence to ensure they are completely identical. In this example, both are the same last record, so the ship positioning and navigation data frame is directly generated and sent to the port shore-based navigation display terminal and the waterway vessel monitoring system interface. The experimental results show that the current data frame output link maintains continuous navigation recording with 97% efficiency, and reduces the average distance error by 60 meters compared to the control scheme without deviation replacement.

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A shore-based positioning and navigation system based on a digital radar transponder, characterized in that, The system includes: The pulse response acquisition module receives the pulse sequence output by the shore-based digital radar transmitter, the transmitted signal from the shore-based radar transmitting antenna, and the response signal returned by the shipborne transponder. Based on the preset response delay rule, it performs time correlation processing on the received signals, records the arrival time of the echo from the shore-based radar receiving antenna, pairs the transmission time and the arrival time of the echo, calculates the propagation time, and arranges them to form a response propagation time sequence. The time difference construction module receives the response propagation time sequence, calls the radar timing unit time reference signal, calculates the adjacent propagation time difference, determines the direction of change and calculates the distance increment, accumulates the distance increment to form a distance change trajectory and generates a continuous distance change sequence. The distance surface generation module receives the continuous distance change sequence, calls the shore-based navigation processing terminal cache unit to calculate the interval average to establish a reference sequence, determines the deviation and replaces abnormal nodes, and generates a continuous distance distribution sequence by mapping the time sequence. The projection residual iteration module receives the continuous distance distribution sequence and the angle sequence output by the shore-based radar azimuth scanning mechanism, performs coordinate transformation to form a projection path set, selects the median time coordinates to calculate the vertical distance to form a residual sequence, filters the residuals to determine the dominant direction and updates the coordinates, and repeats the calculation until the convergence criterion is met to generate the shore-based positioning coordinate result. The navigation result output module receives the shore-based positioning coordinates, calculates the distance and azimuth between the positioning coordinates and the shore-based radar installation point, encapsulates and writes them into the cache to generate a ship positioning and navigation data frame.

2. The shore-based positioning and navigation system based on a digital radar transponder according to claim 1, characterized in that: The response propagation time sequence includes pulse number, round-trip delay value, and sequence time label; the continuous distance change sequence includes cumulative distance, change trend indicator, and trajectory stage marker; the continuous distance distribution sequence includes distribution node set, interval smoothing value, and continuity indicator; the shore-based positioning coordinate result includes shore-based lateral coordinate, shore-based longitudinal coordinate, and positioning information parameters; the ship positioning and navigation data frame includes coordinate field, distance field, and bearing field.

3. The shore-based positioning and navigation system based on a digital radar transponder according to claim 1, characterized in that: The process of calculating the adjacent propagation time difference includes selecting two consecutive propagation time values ​​in the response propagation time sequence according to the time order, performing a difference operation, and limiting the absolute value of the adjacent propagation time difference to be within the range of zero to a preset upper limit time threshold. The preset upper limit time threshold is determined by the maximum ranging period corresponding to the time reference signal of the radar timing unit.

4. The shore-based positioning and navigation system based on a digital radar transponder according to claim 1, characterized in that: The process of determining the direction of change and calculating the distance increment includes comparing the adjacent propagation time difference with zero. A value greater than zero corresponds to the direction of increasing distance, and a value less than zero corresponds to the direction of decreasing distance.

5. The shore-based positioning and navigation system based on a digital radar transponder according to claim 1, characterized in that, The pulse response acquisition module includes: The pulse timing submodule acquires the pulse sequence output by the shore-based digital radar transmitter, records the transmission time corresponding to the pulse, acquires the transmission signal transmitted by the shore-based radar transmitting antenna and extracts the transmission mark, receives the response signal acquired by the shore-based radar receiving antenna and records the corresponding echo arrival time, performs time stamp merging on the transmission time and echo arrival time based on the same pulse mark, and organizes them according to the pulse order to generate a transmission and reception time group. The backhaul pairing submodule calls the transmit and receive time group, receives the echo arrival time recorded by the shore-based radar receiving antenna, establishes the time correlation between the transmit time and the echo arrival time based on the preset delay response rules of the shipborne transponder to the transmitted signal, performs pairing verification on the same pulse marker and establishes the sequential correlation, writes the transmit time and echo arrival time into the data structure, and obtains the time pairing table. The time delay sequence submodule, based on the time pairing table, performs time pairing and sequential arrangement of the transmission time and echo arrival time, calculates the corresponding propagation time value for the paired items, writes them into a continuous storage structure according to the pulse number order, and performs consistency verification on the number order and position relationship to generate the response propagation time sequence.

6. The shore-based positioning and navigation system based on a digital radar transponder according to claim 1, characterized in that, The time difference construction module includes: The differential generation submodule, based on the response propagation time sequence, calls the radar timing unit time reference signal to perform time difference calculation on adjacent propagation times, records the sequence position corresponding to the differential term and writes it into the sequential storage structure, performs sequence sorting on the differential result and maintains the position correspondence, and generates a time difference sequence. The direction increment submodule calls the time difference sequence, detects the time reference signal of the radar timing unit to form a reference time distance, performs change direction determination on the difference term, calculates the distance increment value based on the relationship between the direction mark and the time distance and writes it into the continuous record structure to obtain the distance increment sequence. The trajectory formation submodule performs continuous accumulation of distance increments based on the distance increment sequence and writes them into the trajectory record structure to form trajectory data. It then performs sequential organization of the trajectory data and verifies the sequence position correspondence to generate a continuous distance change sequence.

7. The shore-based positioning and navigation system based on a digital radar transponder according to claim 1, characterized in that, The distance surface generation module includes: The mean parameter building submodule reads the distance increment data by calling the shore-based navigation processing terminal cache unit according to the continuous distance change sequence, detects the interval division position and writes it into the cache structure, performs interval average calculation on the data in the interval, writes it into the reference record area in time order and maintains the sequence correspondence, and generates the interval reference sequence. The deviation replacement submodule calls the interval reference sequence, collects the distance increment corresponding to the continuous distance change sequence, performs deviation judgment on the data item and the reference record, reads the deviation out-of-bounds position and performs replacement processing, and writes the corrected data into the storage structure in the original order to obtain the corrected distance sequence. The mapping submodule obtains the time stamp corresponding to the data item based on the corrected distance sequence, performs mapping processing on the time sequence and writes it into a continuous distribution structure, maintains the correspondence between the sequence position and time, organizes the mapping result into continuously arranged data, and generates a distance continuous distribution sequence.

8. The shore-based positioning and navigation system based on a digital radar transponder according to claim 1, characterized in that, The projection residual iteration module includes: The projection conversion submodule obtains the distance value and azimuth angle corresponding to the time sequence position based on the continuous distance distribution sequence and the angle sequence output by the shore-based radar azimuth scanning mechanism. It performs coordinate transformation on the same time sequence position and writes it into the path record structure, maintaining the correspondence between time order and position. The conversion results are organized into set data according to the scanning order to generate a set of projection paths. The residual orientation submodule calls the projection path set, selects the median time coordinate as the current coordinate, performs vertical distance calculation between the current coordinate and the path and writes it into the residual record structure, forms a residual sequence according to the path order, performs filtering and judgment on the residual distribution and extracts the direction mark to obtain the dominant direction mark. The iterative convergence submodule updates the current coordinates based on the dominant direction marker and the projection path set, repeatedly performs vertical distance calculation on the updated coordinates and records the residual changes, detects the correspondence between the residual changes and the convergence judgment conditions, stops the coordinate update and writes it into the positioning record structure, and generates the shore-based positioning coordinate results.

9. The shore-based positioning and navigation system based on a digital radar transponder according to claim 1, characterized in that, The navigation result output module includes: The coordinate calculation submodule calls the shore-based positioning coordinate results to obtain the shore-based radar installation point coordinate data, performs distance calculation on the positioning coordinates and installation point coordinates and writes them into the record structure, organizes the time-series position data in chronological order and maintains the sequence correspondence, and generates a positioning distance sequence. The azimuth generation submodule obtains the location data corresponding to the shore-based positioning coordinates based on the positioning distance sequence, calls the coordinates of the shore-based radar installation point to perform azimuth angle calculation and writes it into the record structure, organizes the azimuth data in chronological order and establishes a correspondence with the distance sequence to obtain the azimuth angle sequence. The encapsulation output submodule, based on the azimuth sequence and the positioning distance sequence, calls the interface unit of the port shore-based navigation display terminal and the waterway vessel monitoring system to perform data encapsulation and write it into the cache structure in chronological order, maintain the consistency of the data item order, establish a data frame structure, and generate a vessel positioning and navigation data frame.

10. The shore-based positioning and navigation system based on a digital radar transponder according to claim 1, characterized in that: The process of forming a distance change trajectory by accumulating the distance increment value includes accumulating the distance increment value point by point in chronological order, and limiting the change amplitude of a single accumulation result to not exceed a preset distance change threshold. Distance increment values ​​exceeding the preset distance change threshold are truncated before being accumulated to generate the continuous distance change sequence.

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