FPGA-based physical unidirectional transmission system

Abstract

This invention relates to the field of unidirectional transmission system technology, and more particularly to a physical unidirectional transmission system based on FPGA. The system includes a data acquisition module, a monitoring module, an excitation screening module, a steady-state analysis module, a dynamic analysis module, an alarm control module, and a periodic analysis module. This invention constructs an effective throughput rate by acquiring transmission data from the transmitting module itself. Combined with the detected significant rate drop events, it uses this natural step excitation to accurately distinguish between link faults and data link overload faults, and makes targeted responses. When the quality of the transmitted data is deemed unacceptable, the link is disconnected and the data is sent to a temporary storage area. This allows the system to autonomously detect link degradation under conditions where ships are far from shore and frequent manual intervention is impossible, effectively solving the problem of severe data packet loss and inability to intervene in a timely manner due to the inability to detect changes in the quality of the transmitting link.

Description

Technical Field

[0001] This invention relates to the field of unidirectional transmission system technology, and more particularly to a physical unidirectional transmission system based on FPGA. Background Technology

[0002] A physical one-way transmission system is a security protection system used in high-security fields such as industrial control and defense communications. It achieves absolute one-way data flow from the source to the receiver at the physical layer through a hardware-level, irreversible one-way data transmission channel, fundamentally eliminating any possibility of reverse data leakage or communication. It is usually composed of a field-programmable gate array (FPGA) and an Ethernet physical layer (PHY) chip, and the link is usually a copper cable or optical fiber. In the field of marine fisheries, fishing vessels usually need to collect data from various types of sensors in a unified manner, process it in a standardized manner, and then transmit it back to the shore monitoring center via satellite communication. According to the regulations on the management of the position monitoring of ocean-going fishing vessels, the business data of fishing vessels must comply with strict data security and confidentiality requirements. Therefore, the business data of fishing vessels must be collected by the ship's hub equipment, transmitted through the transmitting module via a one-way channel to the receiving module, and then transmitted back to the shore along the satellite link.

[0003] However, the environment of shipboard equipment has inherent unique characteristics. The optical modules and fiber optic connectors of optical cables gradually age and become contaminated due to salt spray corrosion, dust accumulation, or ship vibration. Furthermore, during fishing vessel navigation, changes in the data collection environment or the influence of marine weather can cause significant fluctuations in the data output rate of various sensors. This can lead to instantaneous bursts of traffic in the transmitting module, easily exceeding the normal absorption capacity of the buffer. Ultimately, this results in buffer overflow and packet loss. In a physical one-way transmission system, the transmitting module is unaware of the actual receiving status of the receiving module and cannot dynamically adapt to changes in the link. It can only blindly maintain the original transmission strategy. In addition, the mobility of fishing vessel operations means that equipment maintenance and parameter reconfiguration cannot be performed as frequently as in land-based industrial scenarios. Once the one-way transmission link deteriorates due to hardware aging or environmental interference, if the transmission strategy cannot be adjusted appropriately, critical vessel position data will be permanently lost during data iteration, making it impossible to complete the return transmission. This not only affects the real-time monitoring of fishery management departments but may also endanger the navigation safety of fishing vessels due to interrupted vessel position information.

[0004] Chinese Patent Application Publication No. CN117499141A discloses a unidirectional high-speed communication isolation device based on optical spatial propagation. The system includes an optical transmitter, an optical receiver, and an optical transmission device with a hollow cavity. The optical transmitter and the optical receiver are respectively located at both ends of the optical transmission device. The optical transmitter converts electrical signals into optical signals for transmission and transmits them through the hollow cavity of the optical transmission device using air as a medium. The optical receiver then receives the signals and converts them back into electrical signals.

[0005] Therefore, the aforementioned existing technologies clearly have the following problems: they only achieve physical one-way isolation and lack real-time monitoring of local physical parameters such as optical power and photoelectric conversion efficiency at the transmitting end. When the transmitting end cannot detect the trend of decreasing signal-to-noise ratio and increasing bit error rate at the receiving end, it is easy to cause a large number of data packets to be lost. When buffer overflow or effective throughput decreases, it cannot distinguish whether the root cause is physical link failure or data link overload, resulting in insufficient system adaptability and frequent misjudgments or omissions in the management system. It lacks a periodic evaluation and parameter self-calibration mechanism based on historical transmission quality data. The system cannot adaptively adjust the transmission parameters according to historical data, and it is highly dependent on manual intervention. Summary of the Invention

[0006] To address this, the present invention provides a physical unidirectional transmission system based on FPGA, which overcomes the problem in the prior art of severe data packet loss and inability to intervene in a timely manner due to the inability to detect changes in the quality of the transmission link. This is achieved by monitoring the local physical parameters of the transmitting end in real time.

[0007] To achieve the above objectives, the present invention provides a physical unidirectional transmission system based on FPGA, comprising: The data acquisition module is used to acquire in real time the transmitted optical power and photoelectric conversion efficiency of the transmitting module, the buffer occupancy rate and transmission rate at the network card transmitting ring during one-way data transmission; The monitoring module is used to calibrate the preset transmission interval based on the buffer throughput and preset throughput within the monitoring period, and to determine whether a transmission abnormality has occurred in combination with the transmitted optical power. The buffer throughput is determined based on the transmitted optical power, buffer occupancy rate and transmission rate. The excitation screening module is used to determine whether a step excitation exists based on the judgment result of the occurrence of transmission anomaly, according to the transmission rate, buffer occupancy rate and signal buffer coupling degree within the detection time. The signal buffer coupling degree is determined based on the transmitted optical power and buffer occupancy rate. The steady-state analysis module is used to determine whether there is an optical fiber link anomaly or a data link anomaly based on the judgment result that there is no step excitation, according to the emitted optical power, photoelectric conversion efficiency and buffer occupancy rate within the detection time. The dynamic analysis module is used to determine whether there is an optical fiber link anomaly or a data link anomaly based on the determination result of the presence of step excitation, according to the buffer occupancy rate, transmitted optical power, transmission rate and signal buffer coupling degree within the detection time. The alarm control module is used to issue an alarm or interrupt data transmission based on the determination result of the occurrence of fiber optic link abnormality or data link abnormality. The periodic analysis module is used to calibrate the preset throughput based on the frequency of occurrence of monitored throughput and data link anomalies over a historical period.

[0008] Furthermore, the monitoring module includes: An interval calibration unit is used to calibrate a preset transmission interval based on the buffer throughput and preset throughput within the monitoring period. The buffer throughput is determined by the complement of the throughput scrambling rate and the transmitted optical power, and the throughput scrambling rate is determined based on the buffer occupancy rate and the transmission rate. Interference diagnosis unit, which is used to determine whether a transmission anomaly has occurred based on buffer throughput or transmitted optical power.

[0009] Furthermore, the interval calibration unit includes: The backlog rate determination subunit is used to determine the backlog rate based on the rate of change of buffer occupancy. The throughput determination subunit is used to determine the throughput scrambling rate based on the backlog rate and the transmission rate; The buffer throughput determination subunit is used to determine the buffer throughput based on the complement of the throughput scrambling rate and the transmit efficiency. The emission efficiency determination subunit is used to determine the emission efficiency based on the emitted optical power and the preset optical power; The calibration subunit is used to calibrate the preset transmission interval based on the comparison between the buffer throughput and the preset throughput during the monitoring period.

[0010] Furthermore, the interference diagnostic unit includes: The throughput determination subunit is used to determine the occurrence of a transmission abnormality based on the duration during which the buffer throughput rate is lower than a preset low throughput threshold. The optical power determination subunit is used to determine that a transmission abnormality has occurred based on a preset optical power that is lower than a preset multiple of the transmitted optical power.

[0011] Furthermore, the incentive screening module includes: The duration screening unit is used to screen response observation durations from all observation durations based on the judgment result of an anomaly, according to the buffer occupancy rate and response delay within each observation duration to be screened. The response delay is the difference between the first timestamp when the transmission rate crosses the preset deceleration threshold and the second timestamp when the buffer occupancy rate first falls below the preset high water level threshold. The observation duration to be screened is based on the duration during which the rate of change of the transmission rate within the preset attention duration is lower than the preset deceleration threshold. The excitation determination unit is used to determine whether a step excitation exists based on the comparison between the signal buffer coupling degree and the synchronization ratio threshold within the response observation period. The signal buffer coupling degree is determined based on the correlation analysis between the transmitted optical power and the buffer occupancy rate.

[0012] Furthermore, the steady-state analysis module includes: The optical power analysis unit is used to determine whether there is an optical fiber link anomaly, optical fiber link weakening or optical fiber link health based on the determination result that there is no step excitation, according to the average value of the emitted optical power and the average value of the photoelectric conversion efficiency within the detection time. The congestion analysis unit is used to determine whether a congestion anomaly has occurred in the data link anomaly based on the determination result of fiber optic link weakening and the median buffer occupancy rate within the detection time.

[0013] Furthermore, the steady-state analysis module also includes: The overload analysis unit is used to determine whether an overload anomaly has occurred in the data link anomaly based on the judgment result of the fiber optic link health, according to the median buffer occupancy rate and buffer fluctuation within the detection time. The buffer fluctuation is the difference between the maximum and minimum values ​​of the buffer occupancy rate within the detection time.

[0014] Furthermore, the dynamic analysis module includes: The sending module determination unit is used to determine whether an optical fiber link anomaly has occurred based on the determination result of the presence of step excitation, according to the response delay, emptying time and signal buffer coupling degree within the response observation period. The emptying time is the duration during which the buffer occupancy rate is lower than a preset occupancy threshold within the response observation period. The blocking determination unit is used to determine whether a blocking anomaly has occurred in the data link anomaly based on the determination result that no fiber optic link anomaly has occurred, according to the response delay, emptying time and signal rate follow-up within the response observation time. The signal rate follow-up is determined based on the correlation analysis of transmitted optical power and transmission rate. The overload analysis unit is used to determine whether an overload anomaly has occurred in the data link anomaly based on the judgment result that no blocking anomaly has occurred, according to the signal buffer coupling degree, signal rate follow-up degree and residual backlog during the response observation period. The residual backlog is determined based on the buffer occupancy rate during the response observation period.

[0015] Furthermore, the alarm control module includes: The interruption unit is used to trigger an alarm and interrupt data transmission based on the determination of an optical fiber link anomaly, while storing all data in the backup storage module. The transmission unit is reserved, which is used to alarm and calibrate the preset transmission interval based on the judgment result of the occurrence of a blocking anomaly, while storing non-real-time data into the backup storage module. The overload transmission unit is used to trigger an alarm and calibrate the preset transmission interval based on the determination of an overload anomaly.

[0016] Furthermore, the cycle analysis module includes: The percentage determination unit is used to determine the percentage of blocking based on the frequency of occurrence of blocking anomalies and the frequency of occurrence of data link anomalies. The threshold calibration unit is used to calibrate the preset throughput based on the median of the blocking rate and buffer throughput over a historical period.

[0017] Compared with the prior art, the beneficial effects of the present invention are that, in a one-way transmission system, the quality of the actual data received by the receiving module is affected by both the corrosion and aging of the equipment itself and the instantaneous load changes of the fishing vessel's business data. Equipment factors include aging of the transmitting module, attenuation of transmitted optical power due to pollution, decreased signal-to-noise ratio at the receiving end, and increased bit error rate. The impact of the fishing vessel's business data load changes is due to sudden load fluctuations caused by changes in the business environment, which can easily lead to excessive data transmission, resulting in overflow and packet loss. Furthermore, while facing these two different types of interference, the transmitting module cannot know the actual receiving status at the receiving end, and therefore cannot use data such as the bit error rate and packet loss rate as real-time adjustment parameters. Based on this, the system constructs an effective throughput by collecting transmission data from the sending module itself. Combined with the detected significant rate drop events, it uses the natural step excitation to accurately distinguish between hardware failures of the link itself and transmission failures of the data link caused by hardware aging or data overload, and makes targeted and immediate responses. When it is determined that the quality of the data transmitted by the link is unacceptable, the link is disconnected and the data is sent to a temporary storage area to save critical ocean data. Thus, under the operating conditions of ships operating far from shore for long periods and where frequent manual intervention is not possible, the shipborne one-way transmission system can autonomously detect link degradation to maintain the continuity and reliability of data transmission, and ensure the stability of the return of monitoring data from ocean fishing vessels and navigation safety. Attached Figure Description

[0018] Figure 1 This is a system diagram of the FPGA-based physical unidirectional transmission system in this embodiment; Figure 2 This is a judgment diagram of the interference diagnosis unit in this embodiment; Figure 3 This is a judgment diagram of the excitation screening module in this embodiment; Figure 4 This is the judgment diagram of the steady-state analysis module in this embodiment. Detailed Implementation

[0019] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0020] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0021] Please see Figure 1 As shown, this is a system diagram of the physical unidirectional transmission system based on FPGA in this embodiment, including: a data acquisition module, a monitoring module, an excitation screening module, a steady-state analysis module, a dynamic analysis module, an alarm control module, and a periodic analysis module, all set in the FPGA of the transmitting module.

[0022] The data acquisition module includes an optical power acquisition unit, a photoelectric conversion acquisition unit, a buffer occupancy acquisition unit, and a transmission rate acquisition unit.

[0023] Specifically, the optical power acquisition unit determines the transmitted optical power based on the slope, intercept, and the raw analog-to-digital conversion value of the transmitted optical power combined at addresses 0x66 and 0x67 in the digital diagnostic monitoring register stored in internal addresses 0x5C to 0x5F of the optical module, according to the linear calibration model within the FPGA. The raw analog-to-digital conversion values ​​of the slope, intercept, and transmitted optical power at addresses 0x66 and 0x67 in the digital diagnostic monitoring register stored in internal addresses 0x5C to 0x5F are all obtained after the FPGA sends a read command to the slave address 0xA0 of the optical module in the transmitting module at a clock frequency of 100 kHz.

[0024] The photoelectric conversion acquisition unit is used to calculate the ratio of emitted light power to bias current to obtain the photoelectric conversion efficiency, thereby determining the degree of laser aging. The bias current is determined by combining the original analog-to-digital conversion value of the bias current at addresses 0x64 and 0x65 in the digital diagnostic monitoring register of the optical module, and by performing a linear transformation based on the calibration coefficients at addresses 0x60 to 0x63, in order to obtain the laser drive current intensity in real time.

[0025] The buffer occupancy acquisition unit calculates the ratio of the number of packets to be sent to the total depth to obtain the buffer occupancy rate, thereby determining the data backlog of the sending module. The number of packets to be sent is the difference between the write pointer and the read pointer obtained by the asynchronous ring FIFO for data encapsulation inside the FPGA. The total depth is the size of the block random access memory allocated in the FPGA. The write pointer is controlled by the data encapsulation module and increments by 1 for each packet stored. The read pointer is also controlled by the data encapsulation module and increments by 1 for each packet sent.

[0026] The transmission rate acquisition unit calculates the arithmetic mean of the rate values ​​of the most recent ten windows to obtain the transmission rate, thereby determining the current fishing vessel service injection rate. The rate value of the window is determined by accumulating the number of valid data bits sent by the transmission scheduling module to the physical layer chip in each clock cycle within a preset one-second time window using a 64-bit bit counter inside the FPGA. The number of valid data bits does not include the interframe gap, preamble, and cyclic redundancy check code. The preset one-second time window is driven by a 50 MHz master clock after frequency division by a phase-locked loop.

[0027] The monitoring module is used to determine whether a transmission anomaly has occurred based on the buffer throughput and transmitted optical power within the monitoring period, so as to determine whether it is necessary to enter the deep diagnostic process. The buffer throughput is determined based on the transmitted optical power, buffer occupancy rate and transmission rate to determine the effective data throughput of the current link.

[0028] The excitation screening module is used to determine whether there is a step excitation based on the judgment result of the occurrence of transmission anomaly, according to the transmission rate, buffer occupancy rate and signal buffer coupling degree within the detection time, so as to determine whether the conditions for fine diagnosis using transient response are available. The signal buffer coupling degree is determined based on the transmitted optical power and buffer occupancy rate to determine the degree of correlation between the optical power change and the buffer backlog, and to exclude false excitations dominated by physical layer faults.

[0029] The steady-state analysis module is used to determine whether there is an optical fiber link anomaly or a data link anomaly based on the judgment result that there is no step excitation, according to the emitted optical power, photoelectric conversion efficiency and buffer occupancy rate within the detection time.

[0030] In this embodiment, the detection duration is the time window used in steady-state and static analysis to collect data from the fishing vessel's transmission link and determine statistical characteristics. It is determined based on the typical duration of the buffer response at the network card's transmitting ring with a margin. The shorter the value, the fewer transient features are captured and the greater the fluctuation of the statistics. The longer the value, the more key step response features there are, but the data features tend to be smoother and the real-time diagnostic performance is reduced.

[0031] The dynamic analysis module is used to determine whether there is an optical fiber link anomaly or a data link anomaly based on the judgment result of the presence of step excitation, according to the buffer occupancy rate, transmitted optical power, transmission rate and signal buffer coupling degree within the detection time.

[0032] The alarm control module is used to issue an alarm or interrupt data transmission based on the determination result of an abnormality in the fiber optic link or data link.

[0033] The periodic analysis module is used to calibrate the preset throughput based on the frequency of occurrence of the throughput of interest, fiber optic link anomalies, or data link anomalies over a historical period.

[0034] In this embodiment, the historical duration is the time window for statistical analysis of historical diagnostic results and calculation of long-term trends. It is used to smooth short-term fluctuations and occasional interferences in fishing vessel operations based on a sufficiently long time scale, in order to determine the slow drift in the capture link quality. It is determined based on the typical time fluctuation period of fishing vessel environmental changes in the historical database.

[0035] Because the quality of the actual data received by the receiving module in a one-way transmission system is affected by both the corrosion and aging of the equipment itself and the instantaneous load changes of the fishing vessel's business data, the equipment factors include the aging of the transmitting module, the attenuation of transmitted optical power due to pollution, the decrease in the signal-to-noise ratio at the receiving end, and the increase in the bit error rate. The impact of the fishing vessel's business data load changes is due to the sudden load fluctuations caused by changes in the business environment, which can easily lead to excessive data transmission, resulting in overflow and packet loss. Furthermore, while facing these two different types of interference, the transmitting module cannot know the actual reception status at the receiving end, and therefore cannot use data such as the bit error rate and packet loss rate as a basis for real-time adjustment. Therefore, this system... By collecting and transmitting data from the module itself to build an effective throughput, and combining this with the detected significant rate drop events, the system uses a natural step excitation to accurately distinguish between hardware failures of the link itself and transmission failures of the data link caused by hardware aging or data overload. It then makes targeted and immediate responses. When it is determined that the quality of the data transmitted by the link is unacceptable, the link is disconnected and the data is sent to a temporary storage area to save critical ocean data. Thus, under the operating conditions where the ship is far from the shore for a long time and cannot be frequently manually intervened, the shipborne one-way transmission system can autonomously detect link degradation to maintain the continuity and reliability of data transmission, and ensure the stability of the return of monitoring data from ocean fishing vessels and navigation safety.

[0036] Specifically, the monitoring module includes: The buffer determination unit is used to determine the buffer throughput based on the complement of the throughput scrambling rate and the transmitted optical power, so as to determine the effective throughput of the current link. The throughput scrambling rate is determined based on the buffer occupancy rate and the transmission rate, so as to determine the rate loss ratio caused by buffer backlog or link congestion. Interference diagnosis unit, which is used to determine whether a transmission anomaly has occurred based on buffer throughput or transmitted optical power.

[0037] Since relying solely on buffer occupancy rate is insufficient to distinguish between data fluctuations and transmission link anomalies, it can easily lead to missed or incorrect diagnoses. Therefore, this system determines the buffer throughput by comprehensively considering the estimated values ​​of physical layer optical power and data layer congestion loss, so as to accurately trigger subsequent detailed diagnostic processes when the overall transmission quality is severely degraded or when there is an unrecoverable physical layer failure.

[0038] Specifically, the buffer determination unit includes: The backlog rate determination subunit is used to calculate the product of the rate of change of buffer occupancy and the preset buffer capacity to obtain the backlog rate, so as to determine the amount of backlog data added per unit time due to the transmission rate exceeding the effective throughput of the link.

[0039] The throughput determination subunit is used to calculate the ratio of backlog rate to transmission rate to obtain the throughput scrambling rate, which in turn determines the proportion of rate loss caused by buffer backlog or link congestion.

[0040] The emission efficiency determination subunit is used to calculate the ratio of the emitted optical power to the preset optical power to obtain the emission efficiency, so as to determine the conversion factor of optical power attenuation to effective throughput.

[0041] The buffer throughput determination subunit is used to calculate the product of the complement of the throughput scrambling rate and the transmit efficiency to obtain the buffer throughput, thereby determining the effective throughput of the current link estimate.

[0042] Since the current transmission quality can only be indirectly judged through locally observable buffer occupancy, transmission rate, and transmitted optical power, the system uses buffer occupancy to reflect data backlog caused by the transmission rate exceeding the effective throughput of the link. The transmission rate provides a reference benchmark, and the transmitted optical power approximates the deterioration trend of the physical layer bit error rate as the optical power decreases through the square law. These three parameters represent the performance degradation in two different dimensions: congestion loss and physical attenuation. Successful transmission of data packets requires both conditions to be met: they must not be queued and dropped, and they must not be corrupted by bit errors. Both are necessary conditions and are independent of each other. Therefore, this system predicts the amount of backlogged data added per unit time due to the transmission rate exceeding the effective throughput by using the rate of change of buffer occupancy and the preset buffer capacity. Then, it determines the throughput disturbance rate by using the proportion of the current transmission rate wasted in queuing or overflowing and dropping. Finally, it considers both data layer congestion loss and physical layer attenuation loss to obtain a buffer throughput rate that does not depend on the feedback from the receiving module, which serves as the basis for the subsequent monitoring module's decision.

[0043] Please see Figure 2 As shown, this is a judgment diagram of the interference diagnosis unit in this embodiment. The interference diagnosis unit includes: The throughput determination subunit is used to determine that a transmission abnormality has occurred based on the duration of the buffer throughput rate being lower than a preset low throughput threshold for a period of time that is greater than a preset duration, and to record the transmission abnormality timestamp. The optical power determination subunit is used to determine that a transmission abnormality has occurred based on a preset optical power that is lower than a preset multiple, and to record the transmission abnormality timestamp.

[0044] In this embodiment, the preset low throughput threshold is the minimum acceptable effective throughput limit set in this system. It is determined by an offline calibration experiment in which the transmitted optical power is artificially reduced or the transmission rate is increased in a simulation experiment of the calibrated shipborne equipment in a typical fishing vessel operating environment, and the actual packet loss rate of the receiving end is measured and the corresponding buffer throughput is recorded. This is used to determine the actual requirements of the fishing vessel for the continuity of transmission of key services such as vessel position, fishing logs and alarm information back to the shore via satellite link.

[0045] In this embodiment, the preset duration is used to determine whether the time during which the buffer throughput rate is continuously lower than the preset low throughput threshold has reached the abnormal triggering condition. It is determined based on the average value of the normal fluctuation cycle of the buffer throughput rate in the simulation experiment of the calibrated shipborne equipment in the typical operating environment of the fishing vessel, in order to filter out false triggering caused by instantaneous noise or short-term fluctuations in fishing vessel operations.

[0046] In this embodiment, the preset optical power of the preset multiple is the severe fault threshold multiple of the transmit optical power set in this system. It is determined based on offline experiments or transmit optical power warning thresholds in the optical module datasheet, which monitor the bit error rate of the receiver and the corresponding ratio of optical power to the nominal value during the process of gradually reducing the transmit optical power. This is used to determine the normal fluctuation range of the nominal power of the optical module.

[0047] Please see Figure 3 As shown, this is the judgment diagram of the excitation screening module in this embodiment. The excitation screening module includes: The duration screening unit, in response to the existence of a transmission anomaly timestamp, determines the corresponding observation duration with the longest duration, continuously decreasing buffer occupancy rate, and a response delay less than a preset delay threshold as the response observation duration. This determines an effective transient window that can be used for subsequent dynamic feature extraction. The response delay is the difference between the first timestamp when the transmission rate crosses a preset deceleration threshold and the second timestamp when the buffer occupancy rate first falls below a preset high water level threshold, to determine whether the link's response speed to the rate decrease is normal. The observation duration to be screened is the duration during which the rate of change of the transmission rate within a preset attention period is lower than a preset deceleration threshold, to determine a candidate time window where the transmission rate experiences a stable decrease.

[0048] In this embodiment, a preset high water level threshold is used to determine whether the buffer occupancy rate is in a state of significant backlog. It is determined based on a certain proportion of the total buffer capacity or the inflection point at which the queue delay begins to increase sharply in an offline experiment under typical fishing vessel operating conditions. It is used as a reference benchmark for response delay measurement to determine the time point at which the buffer first falls back below the threshold after the rate decreases.

[0049] In this embodiment, a preset delay threshold is used to determine whether the buffer's response speed to a rate drop event is normal. It is determined based on the actual response delay measured during the experiment in a typical fishing vessel operating environment after calibration of the shipborne equipment, and is set with a safety margin of 3 to 5 times. The larger the value, the more lenient the requirement for response speed, and the easier it is to misjudge a slow response as a valid stimulus. The smaller the value, the stricter the requirement for response speed, and the more likely it is to misjudge a normal link as no stimulus.

[0050] In this embodiment, a preset rate reduction threshold is used to determine whether a step event of a significant decrease in transmission rate has occurred. It is determined based on the normal fluctuation range of historical data of fishing vessel operations, in order to filter out random jitter and retain the true rate reduction event.

[0051] The excitation determination unit is used to determine the presence of a step excitation when the signal buffer coupling degree is greater than the synchronization ratio threshold within the response observation period. It records the excitation timestamp and then determines that there is no strong negative correlation between optical power and buffer, and that the system behavior conforms to the reference calculation model of healthy response. The signal buffer coupling degree is the ratio of the number of times the emitted optical power decrease event and the buffer occupancy increase event occur synchronously to the total number of samples within the response observation period.

[0052] In this embodiment, the synchronization ratio threshold is used to determine the negative correlation strength between transmitted optical power and buffer occupancy rate. It is usually determined based on the correlation coefficient between the two being close to 0 in the simulation experiment of the calibrated shipborne equipment in the typical operating environment of the fishing vessel, and the upper limit of the list of values ​​of the statistical signal buffer coupling degree when simulating hardware failure. This is used to exclude false excitations dominated by hardware failures of the link. It is usually necessary to ensure that the probability of misjudging a faulty link as a false excitation during the experiment does not exceed 5%.

[0053] Since unidirectional transmission systems cannot actively inject probe signals into the link, they can only passively observe changes in the fishing vessel's business data stream. The rate drop event is the only natural step stimulus that the system can obtain. This stimulus can be used to observe dynamic characteristics such as buffer response delay and emptying time, so as to finely distinguish between hardware aging failures caused by ship environmental corrosion and data link overload failures. However, when there is no rate drop event or the link response is severely distorted due to hardware failure when the event occurs, it is difficult to obtain reliable dynamic characteristics. Therefore, this system detects the period when the transmission rate drops beyond the preset rate reduction threshold, selects the effective response observation window, and then determines whether there is an effective step stimulus by analyzing the correlation between optical power and buffer occupancy rate within the window. This determines whether subsequent branches should use dynamic analysis to obtain fine diagnostic results or use steady-state analysis for basic diagnosis when there is no stimulus.

[0054] Please see Figure 4As shown, this is the judgment diagram of the steady-state analysis module in this embodiment. The steady-state analysis module includes: The optical power analysis unit responds to an empty excitation timestamp. Within the detection period, if the average transmitted optical power is lower than a preset optical power fault threshold or the average photoelectric conversion efficiency is lower than a preset efficiency fault threshold, it determines that an optical fiber link is abnormal and records the optical fiber link abnormality timestamp. If the average transmitted optical power is lower than a preset optical power weakening threshold or the average photoelectric conversion efficiency is lower than a preset efficiency weakening threshold, it determines that an optical fiber link is weakened and records the optical fiber link weakening timestamp. Otherwise, it determines that the optical fiber link is healthy and does not record a timestamp.

[0055] In this embodiment, a preset optical power fault threshold is used to determine whether there is a serious fault in the optical fiber link hardware. It is determined based on the lower limit of the transmit optical power warning in the optical module datasheet or the turning point where the bit error rate of the receiver deteriorates sharply in offline experiments.

[0056] In this embodiment, a preset efficiency fault threshold is used to determine whether the fiber optic link hardware has undergone observable corrosion and aging. It is usually determined based on the efficiency statistics of the same type of fiber optic link hardware at the end of its calibrated lifespan, in order to assess whether the optical module needs to be repaired or replaced.

[0057] In this embodiment, a preset optical power attenuation threshold is used to determine whether there is observable slight degradation in the fiber optic link hardware, such as connector contamination or early aging. It is determined based on the lower limit of the normal fluctuation range of optical power of the calibrated shipborne equipment in the simulation experiment of a typical fishing vessel operating environment.

[0058] In this embodiment, a preset efficiency weakening threshold is used to determine whether the laser has shown observable early aging. It is based on the determination of a fixed percentage of lasers of the same model whose efficiency drops to the initial value observable and requires maintenance in the normal aging curve, so as to distinguish between healthy state and weakened state.

[0059] The congestion analysis unit responds to the existence of fiber optic link weakening timestamps and determines the occurrence of data link anomalies based on the median buffer occupancy rate being greater than a preset congestion threshold within the detection period, and records the congestion anomaly timestamp.

[0060] In this embodiment, a preset blocking threshold is used to determine whether the median of the buffer occupancy rate has reached a significant congestion level. It is determined based on the inflection point where the queuing delay begins to increase sharply after the buffer utilization rate of the calibrated shipboard equipment exceeds the critical value in a typical fishing vessel operating environment. This is used to identify indirect congestion caused by fiber optic hardware degradation in the context of weakened fiber optic links.

[0061] Since diagnosis can only be made through steady-state parameters in the absence of step excitation, and fiber optic hardware degradation is the more fundamental cause of transmission link performance degradation, buffer backlog may be caused by fiber optic hardware degradation. However, relying solely on the data from the transmitting module in the absence of step excitation is insufficient to accurately determine whether there is data overload. Therefore, this system uses transmitted optical power and photoelectric conversion efficiency to reflect the degree of attenuation of fiber optic link hardware due to aging in the ship's operating environment, and distinguishes and determines the three states of fiber optic link: abnormal, weakened, or healthy. This allows for the identification of indirect congestion caused by abnormalities in the fiber optic link hardware layer itself and its slight degradation.

[0062] Specifically, the dynamic analysis module includes: The sending module determination unit responds to the existence of an excitation timestamp and determines that an optical fiber link anomaly has occurred based on the response delay being greater than a preset delay fault threshold, the emptying time being greater than a preset emptying fault threshold, and the signal buffer coupling degree being less than a preset strong negative correlation threshold. It records the optical fiber link anomaly timestamp, where the emptying time is the duration during which the buffer occupancy rate is lower than a preset occupancy threshold within the response observation period, and is used to determine the time required for the buffer to be emptied from the congested state to a low level.

[0063] In this embodiment, a preset delay fault threshold is used to determine whether the response delay has reached the level of a severe optical fiber link anomaly. It is determined based on the separation point or average value between the upper bound of the statistical distribution of the measured response delay in a simulation experiment of the calibrated shipborne equipment in a typical fishing vessel operating environment and the lower bound of the statistical distribution of the measured response delay in a simulated severe link fault experiment.

[0064] In this embodiment, a preset emptying fault threshold is used to determine whether the emptying time has reached the level of a serious fiber optic link anomaly. It is determined based on the separation point or average value between the upper percentile of the statistical distribution of the measured emptying time in the simulation experiment of the calibrated shipborne equipment in the typical operating environment of the fishing vessel and the lower percentile of the statistical distribution of the measured emptying time in the simulation experiment of the serious link failure.

[0065] In this embodiment, a preset strong negative correlation threshold is used to determine whether the signal buffer coupling degree has reached the level of strong negative correlation caused by a severe physical layer fault. It is determined based on the separation point or average value between the lower quantile of the statistical distribution of the correlation coefficient between optical power and buffer in the simulation experiment of the calibrated shipborne equipment in the typical operating environment of the fishing vessel and the upper quantile of the statistical distribution of the correlation coefficient in the simulated physical fault link experiment.

[0066] The blocking determination unit responds to the absence of an optical fiber link anomaly timestamp. It determines the occurrence of a blocking anomaly in the data link based on the following conditions within the response observation period: the response delay is less than a preset normal delay threshold, the emptying time is less than a preset normal emptying threshold, and the signal rate follow-up is greater than a preset positive correlation threshold. It records the blocking anomaly timestamp. The signal rate follow-up is the proportion of the number of times the transmission rate decrease event and the transmission optical power decrease event occur synchronously within the response observation period to the total number of samples. It is used to determine the degree of correlation between the optical power fluctuation and the transmission rate.

[0067] In this embodiment, a preset normal delay threshold is used to determine whether the response delay is within a healthy range. It is determined based on the percentile of the upper bound of the statistical distribution of the measured response delay in multiple rate drop events during a simulation experiment of the calibrated shipborne equipment in a typical operating environment of a fishing vessel.

[0068] In this embodiment, a preset normal emptying threshold is used to determine whether the emptying time is within a healthy range. It is determined based on the percentile of the upper bound of the statistical distribution of the measured emptying time in multiple rate decline events during a simulation experiment of the calibrated shipborne equipment in a typical operating environment of a fishing vessel.

[0069] In this embodiment, a preset positive correlation threshold is used to determine whether the signal rate follow-up reaches the positive correlation level caused by fiber optic hardware aging. It is determined based on the upper percentile of the statistical distribution of signal rate follow-up in a simulation experiment of the calibrated shipborne equipment in a typical fishing vessel operating environment.

[0070] Specifically, the dynamic analysis module also includes: The overload analysis unit responds to the empty blocking anomaly timestamp. It is used to determine the overload anomaly in the data link anomaly based on the signal buffer coupling degree being greater than a preset weak negative correlation threshold, the signal rate follow-up being less than a preset low correlation threshold, and the residual backlog being greater than a preset residual backlog threshold within the response observation period. It records the overload anomaly timestamp, where the residual backlog is the buffer occupancy rate at the end of the response observation period, which is used to determine the degree of data backlog after the deceleration event.

[0071] In this embodiment, a preset weak negative correlation threshold is used to determine whether the signal buffer coupling degree is at a level of slight negative correlation that may occur when overloaded. It is determined based on the average value of the statistical distribution of the correlation coefficient between optical power and buffer in a simulation experiment of the calibrated shipborne equipment in a typical fishing vessel operating environment, where the correlation coefficient is close to 0 and the optical power may be slightly negatively correlated when the buffer rises and the optical power stabilizes due to overload.

[0072] In this embodiment, a preset low correlation threshold is used to determine whether the signal rate follow-up is at a low correlation level when overloaded. It is determined based on the average value of the statistical distribution of the optical power in the same simulation experiment as the preset weak negative correlation threshold, where the rate change does not affect the optical power.

[0073] In this embodiment, a preset residual backlog threshold is used to determine whether the buffer occupancy rate is still at a significant backlog level after speed reduction. It is determined based on the statistical distribution of the calibrated shipborne equipment in a simulation experiment of a typical fishing vessel operating environment, where the transmission rate exceeds the link capacity and the buffer is still difficult to empty quickly after appropriate speed reduction.

[0074] Because the system can finely distinguish fault types by observing transient response when step excitation is present, different faults exhibit different combination patterns in time domain and correlation characteristics. Both fiber attenuation and pure overload can lead to prolonged emptying time, but the former is accompanied by a strong negative correlation between optical power and buffer, while the latter is the opposite. When fiber hardware ages normally, the response delay is normal, but the optical power will be positively correlated with the rate fluctuation, while overload anomalies do not have this phenomenon. Relying solely on a single feature or simple threshold can easily confuse hardware faults, blocking anomalies, and overload anomalies. Therefore, by constructing a multi-feature combination mutual exclusion judgment logic, and performing progressive analysis based on the severity and mutual interference, the three anomalies can be distinguished and identified. Moreover, the process is entirely based on the local parameters of the transmitting module for identification within a defined step mechanism, without relying on feedback data from the receiving module.

[0075] Specifically, the alarm control module includes: The interruption transmission unit responds to the timestamp of an optical fiber link anomaly by issuing an optical fiber link alarm and interrupting data transmission. At the same time, it stores all data in a backup storage module and retransmits the data after maintenance is completed.

[0076] A transmission unit is retained, which responds to the timestamp of a blocking anomaly by issuing a blocking anomaly alarm and increasing the preset transmission interval based on a preset emergency adjustment step size. At the same time, non-real-time data is stored in a backup storage module, while real-time data continues to be transmitted according to the calibrated transmission interval to ensure the real-time performance of critical data. The preset emergency adjustment step size is proportional to the interval step size, and its absolute value is greater than the interval step size. The magnitude of its proportionality to the interval step size is designed by the staff according to actual needs, and this embodiment does not impose specific limitations.

[0077] The overload transmission unit responds to the overload abnormal timestamp by issuing an overload abnormal alarm and increasing the preset transmission interval based on a preset emergency adjustment step size.

[0078] The empty unit is used to empty the fiber optic link abnormal timestamp, blocking abnormal timestamp, overload abnormal timestamp, excitation timestamp, and transmission abnormal timestamp.

[0079] Since fiber optic link anomalies are unrecoverable hardware-level faults, continuing to send data will cause the packet loss rate to increase with the severity of the fault. Congestion anomalies are due to minor hardware degradation, where effective throughput has not completely collapsed and the data link is unstable. Overload anomalies are purely data-level problems, caused by a backlog due to the instantaneous rate exceeding capacity, which can be alleviated by conventional speed reduction. Therefore, this system designs differentiated response strategies based on different fault sources, recoverability, and the degree of impact on core data, preserving the transmission quality of only the most critical data to achieve the best balance between data integrity and fishing vessel business continuity at the lowest cost.

[0080] Specifically, the cycle analysis module includes: The percentage determination unit is used to calculate the ratio of the frequency of occurrence of blocking anomalies to the number of occurrences of data link anomalies, so as to obtain the blocking percentage.

[0081] The threshold calibration unit is used to reduce the preset throughput based on an emergency adjustment step size when the median buffer throughput over a historical period is less than a preset low throughput threshold and the blocking percentage is greater than a preset blocking percentage, so as to approximate the actual achievable throughput level. When the median buffer throughput over a historical period is greater than the initial preset throughput and the blocking percentage is less than the preset blocking percentage, the preset throughput is increased based on an emergency adjustment step size to more actively utilize link bandwidth. The emergency adjustment step size is proportional to the difference between the current preset throughput and the median buffer throughput. The magnitude of this proportionality is designed by the staff according to actual needs, and this embodiment does not impose specific limitations.

[0082] In this embodiment, the preset blocking ratio is used to determine whether fiber optic hardware-induced faults dominate all data transmission anomalies. It is determined based on the mean and standard deviation of the statistical distribution of historical diagnostic results during normal operation in a simulation experiment of a typical fishing vessel operating environment.

[0083] In unidirectional transmission systems, severe fiber optic link anomalies immediately interrupt transmission, with no further diagnostic records generated. Congestion anomalies in data links are typically caused by indirect congestion due to fiber optic hardware aging, while overload anomalies are usually caused by pure data overload unrelated to hardware. The ratio of these two factors accurately reflects the cause of the link performance bottleneck. A high congestion ratio indicates a permanent reduction in effective link throughput, necessitating a downward adjustment of the preset throughput target to avoid blindly increasing feedforward speeds and causing packet loss. Conversely, a high overload ratio indicates a healthy physical layer and sufficient bandwidth, requiring maintenance or upward adjustment of the preset throughput to fully utilize link capacity. Therefore, this system further adjusts the preset throughput based on the median of the congestion ratio and buffer throughput over historical periods to closely approximate the actual achievable throughput level of the transmission link, enabling the preset throughput to slowly and stably adapt to equipment aging and contamination accumulation.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A physical unidirectional transmission system based on FPGA, characterized in that, include: The data acquisition module is used to acquire in real time the transmitted optical power and photoelectric conversion efficiency of the transmitting module, the buffer occupancy rate and transmission rate at the network card transmitting ring during one-way data transmission; The monitoring module is used to determine whether a transmission anomaly has occurred based on the buffer throughput and transmitted optical power within the monitoring period. The buffer throughput is determined based on the transmitted optical power, buffer occupancy rate, and transmission rate. The excitation screening module is used to determine whether a step excitation exists based on the judgment result of the occurrence of transmission anomaly, according to the transmission rate, buffer occupancy rate and signal buffer coupling degree within the detection time. The signal buffer coupling degree is determined based on the transmitted optical power and buffer occupancy rate. The steady-state analysis module is used to determine whether there is an optical fiber link anomaly or a data link anomaly based on the judgment result that there is no step excitation, according to the emitted optical power, photoelectric conversion efficiency and buffer occupancy rate within the detection time. The dynamic analysis module is used to determine whether there is an optical fiber link anomaly or a data link anomaly based on the determination result of the presence of step excitation, according to the buffer occupancy rate, transmitted optical power, transmission rate and signal buffer coupling degree within the detection time. The alarm control module is used to issue an alarm or interrupt data transmission based on the determination result of the occurrence of fiber optic link abnormality or data link abnormality. The periodic analysis module is used to calibrate the preset throughput based on the frequency of occurrence of monitored throughput and data link anomalies over a historical period.

2. The FPGA-based physical unidirectional transmission system according to claim 1, characterized in that, The monitoring module includes: A buffer determination unit is used to determine the buffer throughput based on the complement of the throughput scrambling rate and the transmitted optical power, wherein the throughput scrambling rate is determined based on the buffer occupancy rate and the transmission rate. Interference diagnosis unit, which is used to determine whether a transmission anomaly has occurred based on buffer throughput or transmitted optical power.

3. The FPGA-based physical unidirectional transmission system according to claim 2, characterized in that, The buffer determination unit includes: The backlog rate determination subunit is used to determine the backlog rate based on the rate of change of buffer occupancy. The throughput determination subunit is used to determine the throughput scrambling rate based on the backlog rate and the transmission rate; The emission efficiency determination subunit is used to determine the emission efficiency based on the emitted optical power and the preset optical power; The buffer throughput determination subunit is used to determine the buffer throughput based on the complement of the throughput scrambling rate and the transmit efficiency.

4. The FPGA-based physical unidirectional transmission system according to claim 3, characterized in that, The interference diagnostic unit includes: The throughput determination subunit is used to determine the occurrence of a transmission abnormality based on the duration during which the buffer throughput rate is lower than a preset low throughput threshold. The optical power determination subunit is used to determine that a transmission abnormality has occurred based on a preset optical power that is lower than a preset multiple of the transmitted optical power.

5. The FPGA-based physical unidirectional transmission system according to claim 4, characterized in that, The incentive screening module includes: The duration screening unit is used to screen response observation durations from all observation durations based on the judgment result of an anomaly, according to the buffer occupancy rate and response delay within each observation duration to be screened. The response delay is the difference between the first timestamp when the transmission rate crosses the preset deceleration threshold and the second timestamp when the buffer occupancy rate first falls below the preset high water level threshold. The observation duration to be screened is based on the duration during which the rate of change of the transmission rate within the preset attention duration is lower than the preset deceleration threshold. The excitation determination unit is used to determine whether a step excitation exists based on the comparison between the signal buffer coupling degree and the synchronization ratio threshold within the response observation period. The signal buffer coupling degree is determined based on the correlation analysis between the transmitted optical power and the buffer occupancy rate.

6. The FPGA-based physical unidirectional transmission system according to claim 5, characterized in that, The steady-state analysis module includes: The optical power analysis unit is used to determine whether there is an optical fiber link anomaly or optical fiber link weakening based on the determination result that there is no step excitation, according to the average value of the emitted optical power and the average value of the photoelectric conversion efficiency within the detection time. The congestion analysis unit is used to determine whether a congestion anomaly has occurred in the data link anomaly based on the determination result of fiber optic link weakening and the median buffer occupancy rate within the detection time.

7. The FPGA-based physical unidirectional transmission system according to claim 6, characterized in that, The dynamic analysis module includes: The sending module determination unit is used to determine whether an optical fiber link anomaly has occurred based on the determination result of the presence of step excitation, according to the response delay, emptying time and signal buffer coupling degree within the response observation period. The emptying time is the duration during which the buffer occupancy rate is lower than a preset occupancy threshold within the response observation period. The blocking determination unit is used to determine whether a blocking anomaly has occurred in the data link anomaly based on the determination result that no fiber optic link anomaly has occurred, according to the response delay, emptying time and signal rate follow-up within the response observation time. The signal rate follow-up is determined based on the correlation analysis of transmitted optical power and transmission rate.

8. The FPGA-based physical unidirectional transmission system according to claim 7, characterized in that, The dynamic analysis module also includes: The overload analysis unit is used to determine whether an overload anomaly has occurred in the data link anomaly based on the judgment result that no blocking anomaly has occurred, according to the signal buffer coupling degree, signal rate follow-up degree and residual backlog during the response observation period. The residual backlog is determined based on the buffer occupancy rate during the response observation period.

9. The FPGA-based physical unidirectional transmission system according to claim 8, characterized in that, The alarm control module includes: The interruption unit is used to trigger an alarm and interrupt data transmission based on the determination of an optical fiber link anomaly, while storing all data in the backup storage module. The transmission unit is reserved, which is used to alarm and calibrate the preset transmission interval based on the judgment result of the occurrence of a blocking anomaly, while storing non-real-time data into the backup storage module. The overload transmission unit is used to trigger an alarm and calibrate the preset transmission interval based on the determination of an overload anomaly.

10. The FPGA-based physical unidirectional transmission system according to claim 9, characterized in that, The cycle analysis module includes: The percentage determination unit is used to determine the percentage of blocking based on the frequency of occurrence of blocking anomalies and the frequency of occurrence of data link anomalies. The threshold calibration unit is used to calibrate the preset throughput based on the median of the blocking rate and buffer throughput over a historical period.

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