Grating array vibration sensing demodulator and train positioning system

Abstract

The invention provides a grating array vibration sensing demodulator and a train positioning system. The grating array vibration sensing demodulator comprises a light source, a sensing optical cable, an interferometer and a processing unit, the light source is used for generating and outputting detection pulse light to the sensing optical cable; the sensing optical cable is arranged along a train track and is used for sensing vibration caused by train running and generating a return optical signal; the interferometer is used for converting the returned optical signal into a target optical signal carrying vibration phase information; and the processing unit is used for receiving the target optical signal, performing dual-channel independent demodulation on the target optical signal to obtain a first demodulation result and a second demodulation result, and taking the first demodulation result or the second demodulation result as an effective vibration sensing state signal when the first demodulation result and the second demodulation result are the same. A double-channel independent demodulation and result comparison mechanism is adopted, the demodulation reliability of the grating array vibration sensing demodulator is improved, and the grating array vibration sensing demodulator can be directly applied to train control scenes with extremely high safety requirements.

Description

Technical Field

[0001] This invention relates to the field of grating array sensing technology, specifically to a grating array vibration sensing demodulator and a train positioning system. Background Technology

[0002] In the field of train operation control and condition monitoring, achieving high-precision and high-reliability sensing of parameters such as train position is a crucial core technology. Traditional train positioning systems mainly rely on electrical sensors, such as axle counters or track circuits. These technologies form section positioning capabilities by deploying sensors at kilometer-level intervals (e.g., 1 kilometer) along the track. Such solutions have inherent limitations: first, their positioning accuracy is limited by the sensor spacing, typically only at the kilometer level, which cannot meet the needs of modern train's refined control; second, the system deployment is complex, costly, and susceptible to electromagnetic interference.

[0003] To overcome the aforementioned shortcomings, the industry has begun exploring next-generation solutions based on grating array sensing technology. This technology utilizes gratings continuously inscribed in optical fibers as sensing units, enabling distributed, high-precision measurement of physical quantities such as vibration, strain, and temperature along the track. Theoretically, by sensing track vibrations caused by train operation and using meter-level spacing gratings in the sensing optical cable for positioning, positioning accuracy and information richness far exceeding traditional technologies can be achieved. However, applying this theory to train control with high safety requirements still faces a key challenge: how to construct a dedicated demodulator that meets the ultra-high reliability requirements of train control systems. Existing general-purpose fiber optic sensing demodulation schemes typically employ a single signal processing link, whose reliability cannot meet the level requirements of train safety. A single point of failure may lead to erroneous vibration or positioning signal output, which is absolutely unacceptable in train control scenarios.

[0004] Therefore, there is an urgent need to provide a grating array vibration sensor demodulator and a train positioning system that can accurately determine the train vibration sensing status signal, so as to improve the accuracy of train positioning based on this signal. Summary of the Invention

[0005] In view of this, it is necessary to provide a grating array vibration sensor demodulator and a train positioning system to solve the technical problem that the existing technology is based on demodulation through a single demodulation channel, which is not reliable enough and therefore cannot be adapted to the high reliability and high safety requirements of train positioning, resulting in erroneous demodulation results and thus failing to effectively achieve train positioning.

[0006] To address the aforementioned technical problems, in a first aspect, the present invention provides a grating array vibration sensing demodulator, comprising: a light source, a sensing optical cable, an interferometer, and a processing unit;

[0007] The light source is used to generate and output probe pulse light to the sensing optical cable; The sensing optical cable is laid along the train track to sense the vibrations caused by the train's movement and generate a return optical signal; The interferometer is used to convert the returned optical signal into a target optical signal carrying vibration phase information; The processing unit is used to receive the target optical signal and perform dual-channel independent demodulation on the target optical signal to obtain a first demodulation result and a second demodulation result. When the first demodulation result and the second demodulation result are the same, the first demodulation result or the second demodulation result is used as a valid vibration sensing state signal.

[0008] In one possible implementation, the processing unit includes a splitter and separate first-path processing unit, second-path processing unit, and comparison unit; The splitter is used to divide the target optical signal into a first optical signal and a second optical signal; The first processing unit is used to demodulate the first optical signal and generate the first demodulation result; The second processing unit is used to demodulate the second optical signal and generate the second demodulation result; The comparison unit is used to determine whether the first demodulation result and the second demodulation result are the same. If they are the same, the first demodulation result or the second demodulation result is used as the valid vibration sensing state signal. If they are different, the first demodulation result and the second demodulation result are discarded.

[0009] In one possible implementation, both the first processing unit and the second processing unit include a photodetector, an analog-to-digital converter, a first FPGA chip, and a second FPGA chip. The photodetector is used to convert the optical signal from the first optical signal or the second optical signal into an analog electrical signal; The analog-to-digital converter is used to convert the analog electrical signal into a digital electrical signal; The first FPGA chip is used to demodulate the digital electrical signal to obtain the vibration phase signal; The second FPGA chip is used to generate the first demodulation result or the second demodulation result based on the vibration phase signal.

[0010] In one possible implementation, the sampling rate of the analog-to-digital converter is not less than 250MHz.

[0011] In one possible implementation, the light source includes a laser and a pulse modulation module; The laser is used to generate laser light, and the pulse modulation module is used to pulse modulate the laser light to generate pulsed light.

[0012] In one possible implementation, the linewidth of the pulsed light is less than or equal to 100 kHz.

[0013] In one possible implementation, the grating array vibration sensor demodulator further includes a power supply for powering the light source and the processing unit.

[0014] In one possible implementation, the interferometer is a Mach-Zehnder interferometer.

[0015] In one possible implementation, the grating array vibration sensing demodulator further includes an amplifier disposed between the sensing optical cable and the interferometer, the amplifier being used to amplify the returned optical signal and transmit it to the interferometer.

[0016] Secondly, the present invention also provides a train positioning system, including a grating array vibration sensor demodulator and a host computer; The grating array vibration sensor demodulator is used to acquire effective vibration sensing status signals during train operation. The host computer is used to determine the train position, train direction of travel, and train speed based on the effective vibration sensing status signal. The grating array vibration sensor demodulator is any of the grating array vibration sensor demodulators described in any of the above possible implementations.

[0017] The beneficial effects of this invention are as follows: The grating array vibration sensing demodulator provided by this invention performs dual-channel independent demodulation of the target optical signal by setting up a processing unit. Only when the first demodulation result and the second demodulation result are identical is it determined to be a valid vibration sensing state signal. This employs a dual-channel independent demodulation and result comparison mechanism. The dual channels are processed in parallel throughout the entire process and are physically isolated. The final output only takes effect when the two results are completely consistent. Any momentary fault, interference, or error in any single channel will be immediately identified and suppressed. This improves the demodulation reliability of the grating array vibration sensing demodulator, enabling it to be directly applied to train control scenarios with extremely high safety requirements. Attached Figure Description

[0018] 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.

[0019] Figure 1 A schematic diagram of an embodiment of the grating array vibration sensor demodulator provided by the present invention; Figure 2 A schematic flowchart of an embodiment of the processing unit judgment process provided by the present invention; Figure 3 A schematic diagram of an embodiment of the first processing unit and the second processing unit provided by the present invention; Figure 4 This is a schematic diagram of an embodiment of the train positioning and demodulation system provided by the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] It should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this invention illustrate operations implemented according to some embodiments of the invention. It should be understood that the operations in the flowcharts may be implemented out of order, and steps without logical contextual relationships may be reversed or performed simultaneously. Furthermore, those skilled in the art, guided by the content of this invention, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] This invention provides a grating array vibration sensor demodulator and a train positioning system, which are described below.

[0024] Figure 1 This is a schematic diagram of an embodiment of the grating array vibration sensing demodulator provided by the present invention, as shown below. Figure 1As shown, the grating array vibration sensor demodulator 10 includes: a light source 100, a sensing optical cable 200, an interferometer 300, and a processing unit 400; The light source 100 is used to generate and output detection pulse light to the sensing optical cable 200; The sensing optical cable 200 is laid along the train track to sense the vibrations caused by the train's movement and generate a return optical signal.

[0025] Interferometer 300 is used to convert the returned optical signal into a target optical signal carrying vibration phase information.

[0026] The processing unit 400 is used to receive the target optical signal and perform dual-channel independent demodulation on the target optical signal to obtain a first demodulation result and a second demodulation result. When the first demodulation result and the second demodulation result are the same, the first demodulation result or the second demodulation result is used as an effective vibration sensing state signal.

[0027] Among them, the sensing optical cable 200 is a surface-mounted vibration sensing optical cable, which is attached to the train track to sense the vibration signal of the train and generate a return optical signal. At the same time, in order to improve demodulation accuracy, the spacing between the gratings in the sensing optical cable 200 is on the meter level, thereby enabling meter-level demodulation and positioning.

[0028] Interferometer 300 is a passive optical device that converts the returned optical signal into a target optical signal carrying phase information through interference. In a specific embodiment of the invention, the interferometer is a Mach-Zehnder (MZ) interferometer. The Mach-Zehnder interferometer, through its inherent two-beam interference structure, interferes the returned light from the sensing optical cable 200 with a stable reference beam, thereby linearly converting the optical phase modulation, which is difficult to detect directly, into an optical intensity modulation that is easy to measure. This conversion mechanism has extremely high sensitivity, capable of detecting subwavelength optical path changes caused by extremely weak vibrations. More importantly, as an all-fiber passive device, the MZ interferometer has a compact structure, good environmental stability, and requires no complex calibration, making it very suitable for embedding in industrial field equipment with extremely high reliability requirements.

[0029] In a specific embodiment of the present invention, the target optical signal is:

[0030] In the formula, D represents the target optical signal; A represents a fixed DC optical intensity; D represents a fixed gain. This is the initial phase; This refers to the phase change caused by vibration.

[0031] Specifically, the phase change caused by vibration can be solved from the target optical signal. The phase change caused by vibration is related to the optical path difference caused by the vibration of the sensing optical cable 200. The relationship is as follows:

[0032] In the formula, This is the refractive index of the optical fiber, specifically 1.467; The wavelength at the center of the light source is 1550.12 nm.

[0033] Among them, optical path difference The deformation S produced by vibration is linearly related, specifically:

[0034] In the formula, The physical spacing of the grating in the sensing optical cable.

[0035] The calculation formula for the target light signal in the above three formulas reveals that the target light signal output by the interferometer includes phase changes caused by vibration. First, the specific object and target of signal demodulation are clearly defined. Second, the phase-optical path difference formula quantitatively converts the demodulated phase information into the physical deformation of the optical fiber, establishing a deterministic relationship between optical measurement and mechanical vibration. Finally, the optical path difference-deformation formula directly correlates the physical deformation with a specific spatial position (defined by the fixed grating spacing d), proving in principle that positioning can be achieved by identifying which sensing point undergoes deformation, and that the theoretical positioning accuracy is equal to the grating spacing d.

[0036] Compared with existing technologies, the grating array vibration sensing demodulator 10 provided in this embodiment of the invention performs dual-channel independent demodulation of the target optical signal by setting up a processing unit 400. Only when the first demodulation result and the second demodulation result are identical is it determined to be a valid vibration sensing state signal. This employs a dual-channel independent demodulation and result comparison mechanism. The dual channels are processed in parallel throughout and physically isolated, with the final output only effective when the two results are completely consistent. Any momentary fault, interference, or error in a single channel is immediately identified and suppressed. This improves the demodulation reliability of the grating array vibration sensing demodulator 10, enabling its direct application in train control scenarios with extremely high safety requirements.

[0037] In some embodiments of the present invention, such as Figure 1 As shown, the light source 100 includes a laser 110 and a pulse modulation module 120; Laser 110 is used to generate laser light, and pulse modulation module 120 is used to pulse modulate the laser light to generate pulsed light.

[0038] Specifically, the pulse modulation module 120 is an SOA pulse modulation module.

[0039] In traditional continuous-wave light sources used in long-distance grating array sensing, the returned signal is continuous light, causing the reflected light from sensors at different positions to overlap in the time domain. This makes spatial differentiation impossible using time-of-flight, thus hindering precise spatial positioning based on the principle of time-domain reflection of light pulses. Furthermore, continuous light has a low signal-to-noise ratio when detecting transient vibration signals, making it difficult to extract effective vibration events from background noise. Therefore, this embodiment of the invention introduces a pulse modulation module 120 to modulate the laser into narrow pulses with high peak power. This ensures that each pulse, as it propagates in the sensing optical cable, has a time-domain correspondence between its reflected light pulse sequence and the grating position. This provides the system with a clear timestamp reference, enabling the processing unit 400 to uniquely determine the physical location of the vibration event by accurately measuring the pulse's return time. This fundamentally achieves distributed positioning capabilities and significantly improves the signal-to-noise ratio of transient vibration signals.

[0040] It is important to note that if the linewidth of the pulsed light is too wide, its coherence length will be significantly shortened. This leads to a decrease in the coherence between the two beams used for interference after long-distance transmission, resulting in a deterioration in the contrast of the interference signal output by the interferometer 300, or even the inability to produce effective interference fringes. This will severely reduce the system's sensitivity and measurement accuracy for detecting minute phase changes, making it impossible for the system to stably calculate the phase information caused by the weak vibrations of the train.

[0041] Therefore, in a preferred embodiment of the present invention, the linewidth of the pulsed light is less than or equal to 100 kHz and the pulse width is 30 ns.

[0042] This invention, by limiting the pulse width to within 100kHz, ensures that the light source has a sufficiently long coherence length, far exceeding the interferometer optical path difference and sensing distance of the system. This ensures that light pulses returning from gratings at different distances maintain high temporal and spatial coherence when they meet in the interferometer, thereby generating a high-contrast, high-stability interference light signal. This lays the physical foundation for subsequent processing units to demodulate the phase changes carrying vibration information with high precision and high sensitivity.

[0043] In some embodiments of the present invention, such as Figure 1 As shown, the processing unit 400 includes a splitter 410 and independent first processing unit 420, second processing unit 430, and comparison unit 440. Splitter 410 is used to split the target optical signal into a first optical signal and a second optical signal.

[0044] It should be noted that, in order to ensure that the circuit design of the subsequent first processing unit 420 and the second processing unit 430 is completely consistent and no additional gain settings are introduced, in the preferred embodiment of the present invention, the splitter 410 has a 5:5 allocation ratio. Without considering the complexity of subsequent circuit design, the allocation ratio of the splitter 410 can be determined according to actual needs or all available components.

[0045] The first processing unit 420 is used to demodulate the first optical signal and generate a first demodulation result; The second processing unit 430 is used to demodulate the second optical signal and generate a second demodulation result.

[0046] It should be noted that the first processing unit 420 and the second processing unit 430 are completely independent hardware circuits.

[0047] The comparison unit 440 is used to determine whether the first demodulation result and the second demodulation result are the same. If they are the same, the first demodulation result or the second demodulation result is used as a valid vibration sensing state signal. If they are different, the first demodulation result and the second demodulation result are discarded.

[0048] In a specific embodiment of the present invention, the specific judgment process of the processing unit 400 is as follows: Figure 2 As shown, after receiving the target optical signal, the target optical signal is divided into a first optical signal and a second optical signal. The first processing unit 420 is used to demodulate the first optical signal. Starting from the first grating sensor in the sensing optical cable, the vibration sensing signal Xi of the first grating sensor is obtained. It is determined whether Xi is greater than the signal threshold a. If it is greater, the state of the first grating sensor is determined to be occupied. If it is less than or equal to a, the state of the first grating sensor is determined to be idle. After the determination is completed, the state of the second grating sensor is determined, until the state of all grating sensors is determined, and the first demodulation result Z1 composed of the occupancy states of multiple grating sensors is obtained. Similarly, the second processing unit 430 demodulates the second optical signal. Starting from the first grating sensor in the sensing optical cable, it obtains the vibration sensing signal Yi of the first grating sensor, determines whether Yi is greater than the signal threshold a. If it is greater, the state of the first grating sensor is determined to be occupied; if it is less than or equal to a, the state of the first grating sensor is determined to be idle. After the determination is completed, the state of the second grating sensor is determined, until the state of all grating sensors is determined, and a second demodulation result Z2 is obtained, which consists of the occupancy states of multiple grating sensors. After obtaining the first demodulation result Z1 and the second demodulation result Z2, the comparison unit 440 compares whether Z1 and Z2 are the same. If they are the same, Z1 or Z2 is taken as a valid vibration sensing state signal; if they are different, the first demodulation result and the second demodulation result are discarded.

[0049] It should be noted that the signal threshold 'a' can be calculated using the formula... and By combining the typical vibration deformation S of the track with the back-calculation setting, the accuracy of the signal threshold setting is ensured, thereby improving the accuracy of state judgment.

[0050] The embodiments of the present invention improve the accuracy of determining whether the first demodulation result and the second demodulation result are the same by judging and comparing the occupancy status of each grating sensor one by one, thereby improving the demodulation reliability.

[0051] In specific embodiments of the present invention, such as Figure 3 As shown, both the first processing unit 420 and the second processing unit 430 include a photodetector 401, an analog-to-digital converter 402, a first FPGA chip 403, and a second FPGA chip 404. Photodetector 401 is used to convert the optical signal from the first optical signal or the second optical signal into an analog electrical signal; The analog-to-digital converter 402 is used to convert analog electrical signals into digital electrical signals; The first FPGA chip 403 is used to demodulate the digital electrical signal to obtain the vibration phase signal; The second FPGA chip 404 is used to generate a first demodulation result or a second demodulation result based on the vibration phase signal.

[0052] Specifically, the photodetector 401 can be a high-speed PIN photodiode or an avalanche photodiode (APD), whose operating wavelength matches the center wavelength (1550.12nm) of the light source 100. Its core function is to linearly convert the optical signal from the splitter into an analog current signal.

[0053] The analog-to-digital converter 402 can be a high-speed, high-precision ADC chip with a sampling rate set to no less than 250MHz to satisfy the Nyquist sampling theorem and digitize the vibration signal without distortion. Its core function is to convert the analog electrical signal output by the photodetector 401 into a digital signal sequence that can be processed by the FPGA under precise clock control.

[0054] The first FPGA chip 403 is configured as the core digital demodulation logic unit. Its main task is to calculate in real time the phase change caused by the vibration of each grating sensor. Specifically, the working process of the first FPGA chip 403 is essentially to... This formula is solved in real time to extract... .

[0055] The execution process of the second FPGA chip 404 is as follows: for each grating sensor corresponding to A threshold is determined. If the value is greater than the threshold, the state of the corresponding position of the grating sensor is determined to be "occupied". Otherwise, the state of the corresponding position of the grating sensor is determined to be "idle". Then, the determination results are combined into a state array according to the position order.

[0056] The return optical signal from the sensing optical cable 200 after sensing train vibration becomes extremely weak due to inherent losses during long-distance fiber transmission and numerous grating reflections. When this weak signal is directly input into the interferometer 300 and subsequent processing unit 400, it causes a severe deterioration in the signal-to-noise ratio of the electrical signal. This makes it difficult for the system to stably and accurately extract the minute phase change information caused by vibration from the noise background, thus affecting the sensitivity and reliability threshold of the demodulator for vibration events, which is particularly prominent in long-distance or strongly attenuated application scenarios.

[0057] To solve this technical problem, in some embodiments of the present invention, such as Figure 1 As shown, the grating array vibration sensor demodulator 10 also includes an amplifier 500 disposed between the sensing optical cable 200 and the interferometer 300. The amplifier 500 is used to amplify the returned optical signal and transmit it to the interferometer 300.

[0058] This embodiment of the invention, by setting up amplifier 500, pre-amplifies the weak returned optical signal, significantly increasing the optical power input to interferometer 300. This, in turn, greatly improves the signal-to-noise ratio of the electrical signal obtained from subsequent photoelectric conversion, ensuring that phase modulation caused by weak vibrations can be clearly identified, thereby enhancing the system's ability to detect remote or weak vibration events. Simultaneously, it enables the grating array vibration sensing demodulator 10 to operate stably under more demanding link loss conditions, ensuring the engineering practicality of achieving continuous and reliable vibration sensing along long-distance tracks required for train control.

[0059] Since the operation of the light source 100 and the processing unit 400 requires power, therefore, in some embodiments of the present invention, such as Figure 1 As shown, the grating array vibration sensor demodulator 10 also includes a power supply 600, which is used to power the light source 100 and the processing unit 400.

[0060] In summary, the grating array vibration sensing demodulator proposed in this invention firstly improves positioning accuracy by three orders of magnitude compared to the kilometer-level positioning accuracy of traditional electrical sensors, providing a data foundation for precise train positioning. Secondly, through a dual-channel independent demodulation and comparison architecture, it fundamentally solves the potential for single-point faults and improves signal reliability.

[0061] In practical applications, controlling a train requires knowledge of multiple physical parameters, including position, speed, and direction. Therefore, this invention also provides a train positioning system, such as... Figure 4 As shown, the train positioning system 1 includes a grating array vibration sensor demodulator 10 and a host computer 20; The grating array vibration sensor demodulator 10 is used to acquire effective vibration sensing status signals during train operation. The host computer 20 is used to determine the train position, train direction of travel, and train speed based on the effective vibration sensing status signal; Among them, the grating array vibration sensor demodulator 10 is the grating array vibration sensor demodulator in any of the above embodiments.

[0062] As can be seen from the description of the grating array vibration sensor demodulator 10, the effective vibration sensing state signal is a state array. Each element in the state array represents the state of the corresponding grating sensor or the measurement area it represents. Specifically, when the element value is 1, it indicates that the sensor is occupied, and when the element value is 0, it indicates that the sensor is idle.

[0063] Based on this, the logic for determining the train's location is as follows: When a train travels on a track equipped with sensor optical cables, its wheels vibrate continuously. This creates a continuous "1" block (occupied area) in the state array, with the leading and trailing edges of this block corresponding to the positions of the front and rear of the train. In other words, the train's position is determined by finding all consecutive segments with a value of 1 in the state array. Finally, based on a pre-defined "grating sensor index-coordinate" mapping table, the array indexes are converted into actual track mileage markers.

[0064] For example, suppose a track has a sensor array corresponding to a state array of length 10 (for example only), where each element represents a 10-meter track segment.

[0065] The state array at time T1 is: [0, 0, 1, 1, 1, 0, 0, 0, 0, 0] The occupied block indices are 2, 3, and 4, indicating that the train occupies the track from 20 meters to 40 meters. The front of the train is at 40 meters, and the rear is at 20 meters, with a train length of approximately 20 meters.

[0066] Specifically, the logic for determining the direction of travel is as follows: Compare the occupied blocks at two adjacent time points (e.g., t1 and t2). If the occupied block at time t2 moves entirely in the direction of increasing index, the train is traveling in the forward direction (e.g., from station A to station B). If it moves in the direction of decreasing index, the train is traveling in the reverse direction.

[0067] For example, the state array at time T2 (0.1 seconds later) is: [0, 0, 0, 1, 1, 1, 0, 0, 0, 0], with occupied block indices of 3, 4, 5, indicating that the occupied block has moved one index to the right. That is, the front of the car has moved from 40 meters to 50 meters, and the current driving direction is positive, i.e., the direction of index increase.

[0068] Specifically, the logic for determining the driving speed is as follows: Obtain the position P1 of the car's front end at time t1 and the position P2 at time t2. Instantaneous velocity = (P2 - P1) / (t2 - t1).

[0069] Based on the above example, the instantaneous speed v = (50 m - 40 m) / 0.1 sec = 100 m / sec = 360 km / h.

[0070] In addition to determining the three physical parameters mentioned above, in some embodiments of the present invention, the integrity of the train can also be assessed. Specifically: A normal, complete train should have a relatively stable length of occupied blocks, roughly corresponding to the known length of the train. If the length of the occupied block suddenly becomes abnormally short, it may indicate that the train has separated (decoupled), which can trigger a safety alarm to determine and warn of the integrity of the train.

[0071] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware (such as a processor, controller, etc.), and the computer program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0072] The above provides a detailed description of the grating array vibration sensor demodulator and train positioning system provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A grating array vibration sensing demodulator, characterized in that, include: Light source, sensing optical cable, interferometer, and processing unit; The light source is used to generate and output detection pulse light to the sensing optical cable; The sensing optical cable is laid along the train track to sense the vibrations caused by the train's movement and generate a return optical signal; The interferometer is used to convert the returned optical signal into a target optical signal carrying vibration phase information; The processing unit is used to receive the target optical signal and perform dual-channel independent demodulation on the target optical signal to obtain a first demodulation result and a second demodulation result. When the first demodulation result and the second demodulation result are the same, the first demodulation result or the second demodulation result is used as a valid vibration sensing state signal.

2. The grating array vibration sensing demodulator according to claim 1, characterized in that, The processing unit includes a splitter and independent first processing unit, second processing unit, and comparison unit; The splitter is used to divide the target optical signal into a first optical signal and a second optical signal; The first processing unit is used to demodulate the first optical signal and generate the first demodulation result; The second processing unit is used to demodulate the second optical signal and generate the second demodulation result; The comparison unit is used to determine whether the first demodulation result and the second demodulation result are the same. If they are the same, the first demodulation result or the second demodulation result is used as the valid vibration sensing state signal. If they are different, the first demodulation result and the second demodulation result are discarded.

3. The grating array vibration sensing demodulator according to claim 2, characterized in that, Both the first processing unit and the second processing unit include a photodetector, an analog-to-digital converter, a first FPGA chip, and a second FPGA chip. The photodetector is used to convert the optical signal from the first optical signal or the second optical signal into an analog electrical signal; The analog-to-digital converter is used to convert the analog electrical signal into a digital electrical signal; The first FPGA chip is used to demodulate the digital electrical signal to obtain the vibration phase signal; The second FPGA chip is used to generate the first demodulation result or the second demodulation result based on the vibration phase signal.

4. The grating array vibration sensing demodulator according to claim 3, characterized in that, The sampling rate of the analog-to-digital converter is not less than 250MHz.

5. The grating array vibration sensing demodulator according to claim 1, characterized in that, The light source includes a laser and a pulse modulation module; The laser is used to generate laser light, and the pulse modulation module is used to pulse modulate the laser light to generate pulsed light.

6. The grating array vibration sensing demodulator according to claim 5, characterized in that, The linewidth of the pulsed light is less than or equal to 100 kHz.

7. The grating array vibration sensing demodulator according to claim 1, characterized in that, The grating array vibration sensor demodulator also includes a power supply for powering the light source and the processing unit.

8. The grating array vibration sensing demodulator according to claim 1, characterized in that, The interferometer is a Mach-Zehnder interferometer.

9. The grating array vibration sensing demodulator according to claim 1, characterized in that, The grating array vibration sensing demodulator also includes an amplifier disposed between the sensing optical cable and the interferometer, the amplifier being used to amplify the returned optical signal and transmit it to the interferometer.

10. A train positioning system, characterized in that, This includes a grating array vibration sensor demodulator and a host computer; The grating array vibration sensor demodulator is used to acquire effective vibration sensing status signals during train operation. The host computer is used to determine the train position, train direction of travel, and train speed based on the effective vibration sensing status signal. The grating array vibration sensor demodulator is the grating array vibration sensor demodulator according to any one of claims 1-9.

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