Grating fiber demodulation equipment capable of being flexibly expanded

Abstract

The invention relates to the technical field of fiber bragg gratings, and discloses a grating fiber demodulation device capable of being flexibly expanded. The device comprises an internal device and a front-end device, the internal device is provided with an optical fiber external interface docking station, an FPGA control chip and a high-speed analog-to-digital converter, and the front-end device comprises an upper computer and at least one fiber grating sensing unit. Through the optical fiber external interface docking station and the FPGA control chip and in combination with the time division multiplexing technology, real-time increase and decrease of the number of the optical fiber grating sensing units are realized, and internal architectures of an upper computer and other equipment do not need to be changed. The FPGA control chip can automatically identify the connection number and state of the fiber grating sensing units, dynamically adjust the signal acquisition and processing flow, and ensure the accuracy and high efficiency of data acquisition. The equipment has relatively high integration level and expansibility, can meet the requirements on the measurement range and the measurement capability of the fiber bragg grating in different application scenes, and reduces the redesign and installation cost of the equipment.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber gratings and discloses a grating optical fiber demodulation device which can be flexibly expanded. Background Art

[0002] Existing fiber grating instruments are composed of laser light sources, spectrometers, fiber sensors, and related fiber receiving modules, demodulation modules, and output modules. The number and structure of fiber grating sensors cannot be changed after application. When the use scenario changes and the measurement range and measurement capability of the fiber grating need to be increased, it is necessary to redesign or add new instruments to meet the scenario requirements.

[0003] This not only requires a lot of additional funds but also requires professional technicians to invest a lot of time and energy to design and plan the installation of the equipment. Summary of the invention

[0004] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a flexibly expandable grating fiber demodulation device, which can realize the real-time increase or decrease of the number of fiber grating sensor lines of field equipment through time division multiplexing, while keeping the internal architecture of the host computer and other equipment unchanged.

[0005] The present invention adopts the following technical solution: In a first aspect, the present invention provides a flexibly expandable grating fiber demodulation device, including an internal device and a front-end device: Internal equipment includes a fiber-optic external interface docking station, an FPGA control chip, and a high-speed analog-to-digital converter; The optical fiber external interface expansion dock is composed of multiple parallel photoelectric converters and circuit selectors, and is provided with an optical connection status register for storing circuit status; The FPGA control chip is used to identify the number and status of connections of the fiber grating sensor unit, dynamically adjust the control signal of the circuit selector, identify the number of connections of the laser and control the laser, and perform data filtering and parallel demodulation on multi-channel analog signals; High-speed analog-to-digital converter, used to convert analog signals into digital signals; The front-end device includes a host computer and at least one fiber grating sensor unit, each of which includes a laser and its control circuit, a fiber amplifier, a splitter, an optical fiber and a circulator; The internal equipment uses time division multiplexing technology to realize the addition and deletion of fiber grating sensor units in the front-end equipment, and the architecture of the host computer and internal equipment remains unchanged during the addition and deletion process; The optical fiber external interface expansion dock is connected to the circulator of the fiber grating sensor unit through the photoelectric converter to realize the reception and selection of the optical signal; The FPGA control chip is connected to the host computer through the network port, receives control instructions from the host computer, and sends control signals to the laser.

[0006] Preferably, in a possible implementation manner of the first aspect, the workflow of the device includes: Connect the equipment, connect the laser control circuit of the fiber grating sensor unit to the laser control expansion interface of the FPGA control chip, connect the circulator of the fiber grating sensor unit to the photoelectric converter of the fiber external interface expansion dock, connect the fiber external interface expansion dock and the high-speed analog-to-digital converter to the corresponding control pins of the FPGA control chip, and connect the host computer to the network port of the FPGA control chip; Power on and activate, the FPGA control chip identifies and records the number and status of laser connections, the optical fiber external interface docking station identifies and records the number of optical path connections, and the host computer turns on and starts the system and software; Signal acquisition: The host computer sends the control instructions of the laser to the FPGA control chip through the network port. The FPGA control chip sends a sweep signal to the laser according to the status signal of the optical fiber external interface expansion dock and the control signal of the host computer. The laser emits light waves, which are transmitted and sensed through the optical fiber. The sensing light signal undergoes photoelectric conversion and path selection in the optical fiber external interface expansion dock. The high-speed analog-to-digital converter samples and converts the selected electrical signal, and transmits the converted digital signal to the FPGA control chip. Parallel control: the FPGA control chip controls the transmission of the laser and the reception of the circuit selector in a time-division multiplexing manner according to the preset control mode, thus realizing the parallel processing of multiple optical signals; Extended access: When a fiber grating sensor unit needs to be added, the laser control circuit of the newly added fiber grating sensor unit is connected to the laser control expansion interface of the FPGA control chip, and the circulator of the newly added fiber grating sensor unit is connected to the photoelectric converter of the optical fiber external interface expansion dock, and the above steps of power-on activation, signal acquisition and parallel control are repeated.

[0007] Preferably, in a possible implementation manner of the first aspect, after power-on activation, the optical fiber external interface expansion dock identifies the connection state of the optoelectronic conversion interface and stores it in an optical connection state register.

[0008] Preferably, in a possible implementation of the first aspect, the FPGA control chip is connected to the optical fiber external interface expansion dock through the selector control pin, reads the optical connection status register state and transmits the circuit selector path state; the FPGA control chip performs data transmission of demodulation mode and pin connection status with the host computer through the network port; the FPGA control chip sends signals to different front-end devices through time division multiplexing to perform laser scanning and sensor identification.

[0009] Preferably, in a possible implementation manner of the first aspect, the time division multiplexing method includes: The FPGA control chip dynamically allocates time slots to each connected fiber optic Bragg grating sensor unit according to the instructions of the host computer and the records of the optical connection status register in the optical fiber external interface expansion dock; In each time slot, the FPGA control chip controls the corresponding laser to emit a frequency-sweeping optical signal, and selects the optical signal of the corresponding fiber grating sensor unit for reception through the circuit selector in the optical fiber external interface expansion dock; The received optical signal is converted into a digital signal by a photoelectric converter and a high-speed analog-to-digital converter, and then filtered and demodulated by the FPGA control chip. When adding or deleting fiber grating sensor units, the FPGA control chip dynamically adjusts the time slot allocation according to the latest connection status.

[0010] Preferably, in a possible implementation manner of the first aspect, the FPGA control chip receives and processes the digital signal, and determines the fiber grating sensor unit to which the digital signal belongs through a clock.

[0011] Preferably, in a possible implementation manner of the first aspect, the fiber optic external interface expansion dock performs photoelectric conversion on the parallel selector link whose path is activated and transmits the electrical signal to the high-speed analog-to-digital converter.

[0012] Preferably, in a possible implementation manner of the first aspect, the high-speed analog-to-digital converter acquires the electrical signal and transmits it to a filter demodulation pin of the FPGA control chip.

[0013] The beneficial effects of the present invention are: providing a flexibly expandable grating fiber demodulation device, which realizes the real-time increase and decrease of the number of fiber grating sensing units by introducing a fiber external interface expansion dock and an FPGA control chip, combined with time division multiplexing technology, without changing the internal architecture of the host computer and other devices. This not only greatly improves the flexibility and adaptability of the equipment, but also reduces the cost of equipment redesign and installation due to scene changes. In addition, the application of the FPGA control chip enables the device to automatically identify the number and status of connections of the fiber grating sensing unit, and dynamically adjust the signal acquisition and processing process, thereby ensuring the accuracy and efficiency of data acquisition. At the same time, the device also has a high degree of integration and scalability, which can meet the requirements for the measurement range and measurement capability of the fiber grating in different application scenarios, and provides strong support for the application and development of fiber grating technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 A flexibly expandable grating fiber demodulation device structure diagram is provided for this application. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Embodiment 1: Figure 1 As shown, the present invention provides a flexibly expandable grating fiber demodulation device, including an internal device and a front-end device.

[0018] Specifically, the internal equipment includes an optical fiber external interface expansion dock, an FPGA control chip, and a high-speed analog-to-digital converter; the optical fiber external interface expansion dock is composed of multiple parallel photoelectric converters and circuit selectors, and is provided with an optical connection status register for storing circuit status; the FPGA control chip is used to identify the number of connections and connection status of the optical fiber grating sensor unit, dynamically adjust the control signal of the circuit selector, identify the number of connections of the laser and control the laser, perform data filtering and parallel demodulation on multiple analog signals; the high-speed analog-to-digital converter is used to convert analog signals into digital signals.

[0019] The front-end device includes a host computer and at least one fiber grating sensor unit, each of which includes a laser and its control circuit, a fiber amplifier, a splitter, an optical fiber and a circulator; the internal device realizes the addition and deletion of the fiber grating sensor units in the front-end device through time division multiplexing technology, and keeps the architecture of the host computer and the internal device unchanged during the addition and deletion process; the optical fiber external interface expansion dock is connected to the circulator of the fiber grating sensor unit through a photoelectric converter to realize the reception and selection of optical signals; the FPGA control chip is connected to the host computer through a network port, receives control instructions from the host computer, and sends control signals to the laser.

[0020] In this embodiment, the optical fiber external interface expansion dock is used to connect multiple fiber grating sensor units to internal devices, and is composed of multiple parallel photoelectric converters and circuit selectors, which can receive and convert optical signals and selectively route these signals through the circuit selector. The optical connection status register is used to monitor and store the status of each circuit to ensure the stability and reliability of the system.

[0021] The FPGA control chip is the core processor of the demodulation device, responsible for identifying the number and status of connections of the fiber Bragg grating sensor unit, dynamically adjusting the control signal of the circuit selector, controlling the laser, and performing data filtering and parallel demodulation on multiple analog signals. The high-speed analog-to-digital converter is used to convert analog signals into digital signals for further processing by the FPGA.

[0022] Fiber Bragg Grating sensor unit is a sensor based on fiber Bragg grating technology, which is used to measure physical quantities such as temperature, pressure, strain, etc. It usually includes components such as laser and its control circuit, fiber amplifier, splitter, optical fiber and circulator.

[0023] The laser and its control circuit are used to generate stable optical signals, and the intensity and frequency of the optical signals are adjusted through the control circuit; the optical fiber amplifier is used to enhance the intensity of the optical signal to ensure that the signal does not attenuate too much during transmission; the optical splitter divides the optical signal into multiple paths so that multiple parameters can be monitored simultaneously; the optical fiber is the medium for transmitting optical signals, and has the characteristics of low loss, high bandwidth and strong anti-interference; the circulator is a non-reciprocal optical device that allows optical signals to be transmitted in a single direction, and is used to achieve isolation and circulation of optical signals.

[0024] The host computer is the control center of the demodulation device and is an embedded system used to send control instructions to the FPGA control chip and receive and process the demodulated data.

[0025] The workflow of the grating fiber demodulation equipment includes connecting the equipment, power-on activation, signal acquisition, parallel control and expansion access.

[0026] Connect the equipment, connect the laser control circuit of the fiber grating sensor unit with the laser control expansion interface of the FPGA control chip, connect the circulator of the fiber grating sensor unit with the photoelectric converter of the fiber external interface expansion dock, connect the fiber external interface expansion dock and the high-speed analog-to-digital converter with the corresponding control pins of the FPGA control chip, and connect the host computer with the network port of the FPGA control chip.

[0027] In this embodiment, the fiber Bragg grating sensing unit is first connected to the internal device. The laser control circuit of each fiber Bragg grating sensing unit is connected to the laser control expansion interface of the FPGA control chip through a wire. Ensure that the laser can receive the control signal from the FPGA control chip, so as to emit light waves according to the predetermined parameters.

[0028] Then, the circulator of the fiber grating sensor unit is connected to the photoelectric converter of the fiber external interface expansion dock through the fiber interface, so that the optical signal is transmitted from the fiber grating sensor unit to the fiber external interface expansion dock through the optical fiber and undergoes photoelectric conversion, that is, converting the optical signal into an electrical signal.

[0029] Then the optical fiber external interface expansion dock and the high-speed analog-to-digital converter are connected to the corresponding control pins of the FPGA control chip through their respective connection lines or interfaces, so that the FPGA control chip can receive the status signal from the optical fiber external interface expansion dock and the digital signal from the high-speed analog-to-digital converter, thereby realizing the control of the entire demodulation device.

[0030] Finally, the host computer is connected to the network port of the FPGA control chip through a network cable, so that the host computer can send control instructions to the FPGA control chip and receive demodulated data from the FPGA control chip.

[0031] Power-on activation, the FPGA control chip identifies and records the number of connections and status of the laser, the optical fiber external interface expansion dock identifies and records the number of optical path connections, performs photoelectric conversion on the parallel selector link where the path is activated, and transmits the electrical signal to the high-speed analog-to-digital converter, and the host computer starts up and starts the system and software.

[0032] In this embodiment, the entire system is first powered on, and after the power is turned on, each component will perform an initialization operation. Then the FPGA control chip first identifies and records the number and status of the currently connected lasers. The optical fiber external interface expansion dock identifies and records the number of currently connected optical paths. The optical fiber external interface expansion dock monitors and records the connection status of the optical path in real time through its internal photoelectric converter and circuit selector. After powering on, the host computer will perform a series of self-tests and initialization operations to ensure that it can normally receive and process data from the FPGA control chip.

[0033] In addition, during the power-on activation process, the system will also perform some self-test and calibration operations, including the FPGA control chip sending a test signal to the laser to verify whether its working status is normal; the optical fiber external interface expansion dock performs optical path calibration operations to ensure accurate transmission of optical signals.

[0034] Signal acquisition: The host computer sends the control instructions of the laser to the FPGA control chip through the network port. The FPGA control chip sends a sweep signal to the laser according to the status signal of the optical fiber external interface expansion dock and the control signal of the host computer. The laser emits a light wave, which is transmitted and sensed through the optical fiber. The sensed light signal undergoes photoelectric conversion and path selection in the optical fiber external interface expansion dock. The high-speed analog-to-digital converter samples and converts the selected electrical signal, and transmits the converted digital signal to the filter demodulation pin of the FPGA control chip.

[0035] In this embodiment, the host computer first sends control instructions to the FPGA control chip through its network port. These instructions start and configure the laser so that it can emit light waves according to predetermined parameters and modes. After receiving these instructions, the FPGA control chip will dynamically adjust the control signal of the circuit selector according to the number and status of the currently connected lasers and the status signal provided by the optical fiber external interface expansion dock, thereby ensuring that each laser can correctly receive the control instructions and emit light waves.

[0036] Next, the laser starts to emit light waves under the control of the FPGA control chip. These light waves are transmitted through the optical fiber and sensed in the fiber grating sensor unit. During the sensing process, the light waves interact with the fiber grating to generate reflected or transmitted light signals. These light signals carry information about the physical quantity to be measured.

[0037] Then, the sensed optical signal is transmitted to the optical fiber external interface docking station through the optical fiber. After the conversion by the photoelectric converter, the optical signal is converted into an electrical signal. At the same time, the circuit selector in the optical fiber external interface docking station selectively routes these electrical signals according to the instructions of the FPGA control chip so that they can be received and processed by the subsequent processing unit.

[0038] Next, the high-speed analog-to-digital converter samples and converts the selected electrical signal. The FPGA control chip receives the digital signal from the high-speed analog-to-digital converter and further processes and analyzes it.

[0039] Inside the FPGA control chip, the received digital signal is filtered, demodulated, and processed to extract useful information. This information is transmitted to the host computer, which further displays, stores, or processes it. Through the user interface of the host computer, the operator can intuitively see the demodulated data and understand the status of the currently measured physical quantity.

[0040] Parallel control: The FPGA control chip controls the transmission of the laser and the reception of the circuit selector in a time-division multiplexing manner according to the preset control mode, thereby realizing parallel processing of multiple optical signals.

[0041] In this embodiment, the control mode of the FPGA control chip is set in the host computer. The FPGA control chip first determines the specific strategy of parallel control according to the control mode, including the transmission frequency of the laser, the receiving path of the circuit selector and the priority of data processing.

[0042] Next, the FPGA control chip uses time division multiplexing technology to precisely control the transmission of the laser and the reception of the circuit selector. Time division multiplexing is a technology that divides time into multiple time slots, each of which is used to transmit different signals. The FPGA control chip divides time into multiple time slots, and controls a laser to emit light waves in each time slot, while selecting the corresponding circuit selector to receive the sensed light signal.

[0043] When the laser sends light waves, the FPGA control chip sends a frequency sweep signal to the laser. The frequency sweep signal is a signal whose frequency changes with time, which can make the light waves emitted by the laser scan within a specific range. In this way, when the light waves are sensed in the fiber grating sensing unit, they will interact with the fiber gratings of different frequencies, thereby generating reflected or transmitted light signals. These light signals carry information about the state of the fiber grating, such as wavelength deviation, amplitude change, etc.

[0044] At the same time, the circuit selector selectively routes the sensed optical signals under the instruction of the FPGA control chip. These optical signals are converted into electrical signals by the photoelectric converter, and then sampled and converted into digital signals by the high-speed analog-to-digital converter. After receiving these digital signals, the FPGA control chip further processes and analyzes them to extract useful information.

[0045] Since the FPGA control chip has the ability of high-speed parallel processing, it can process signals from multiple fiber grating sensor units at the same time. This means that even when multiple sensor units are working at the same time, the FPGA control chip can ensure that the signal of each sensor unit is processed in a timely and accurate manner.

[0046] In addition, the FPGA control chip also has the ability to dynamically adjust the control signal of the circuit selector and the transmission parameters of the laser according to the number and status of the currently connected fiber grating sensor units and the control instructions of the host computer.

[0047] During the entire parallel control process, the FPGA control chip maintains real-time communication with the host computer. The host computer sends control instructions to the FPGA control chip through the network port and receives demodulated data from the FPGA control chip. In this way, the operator can monitor the system's operating status and demodulation results in real time through the host computer's user interface.

[0048] The time division multiplexing method adopted in this embodiment includes: the FPGA control chip dynamically allocates time slots to each connected fiber grating sensor unit according to the instructions of the host computer and the records of the optical connection status register in the optical fiber external interface expansion dock.

[0049] In each time slot, the FPGA control chip controls the corresponding laser to emit a frequency-sweeping optical signal, and selects the optical signal of the corresponding fiber grating sensor unit for reception through the circuit selector in the optical fiber external interface expansion dock.

[0050] The received optical signal is converted into a digital signal by a photoelectric converter and a high-speed analog-to-digital converter, and then filtered and demodulated by the FPGA control chip. When adding or deleting fiber grating sensor units, the FPGA control chip dynamically adjusts the time slot allocation according to the latest connection status.

[0051] The FPGA control chip receives and processes the digital signal and determines the fiber grating sensor unit to which the digital signal belongs through the clock.

[0052] Extended access: When a fiber grating sensor unit needs to be added, the laser control circuit of the newly added fiber grating sensor unit is connected to the laser control expansion interface of the FPGA control chip, and the circulator of the newly added fiber grating sensor unit is connected to the photoelectric converter of the optical fiber external interface expansion dock, and the above steps of power-on activation, signal acquisition and parallel control are repeated.

[0053] In this embodiment, the laser control circuit of the newly added fiber Bragg grating sensor unit is first connected to the laser control expansion interface of the FPGA control chip through a wire. Then, the circulator of the newly added fiber Bragg grating sensor unit is connected to the photoelectric converter of the fiber external interface expansion dock through the optical fiber interface. In this way, the optical signal emitted by the newly added fiber Bragg grating sensor unit can be transmitted to the fiber external interface expansion dock through the optical fiber, and converted into an electrical signal through the photoelectric converter.

[0054] After completing the above physical connection, the FPGA control chip updates the number and status records of the connected lasers according to the newly added connection. At the same time, the optical fiber external interface expansion dock also updates the number of connected optical paths. After that, the host computer sends control instructions to the FPGA control chip through the network port to start and configure the newly added laser. The FPGA control chip dynamically adjusts the control signal of the circuit selector according to the number and status of the currently connected lasers and the status signal provided by the optical fiber external interface expansion dock.

[0055] The light waves emitted by the newly added fiber grating sensing unit will be transmitted through the optical fiber, and will interact with the fiber grating during the sensing process to generate reflected or transmitted light signals. These light signals carry the information of the physical quantity to be measured and are transmitted to the fiber external interface expansion dock through the optical fiber. After conversion by the photoelectric converter and routing selection by the circuit selector, these light signals are converted into electrical signals, which are sampled and converted into digital signals by the high-speed analog-to-digital converter.

[0056] After receiving the digital signal from the high-speed analog-to-digital converter, the FPGA control chip performs further processing, including filtering, demodulation and other steps, to extract useful information. Then, this information will be transmitted to the host computer for display, storage or further processing.

[0057] Finally, the FPGA control chip dynamically adjusts the parallel control strategy according to the preset control mode and the connection status of the newly added fiber Bragg grating sensor unit, including determining the transmission frequency of the laser, the receiving path of the circuit selector, and the priority of data processing. By adopting the time division multiplexing technology, the FPGA control chip can realize the simultaneous control and data collection of multiple fiber Bragg grating sensor units.

[0058] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A flexibly expandable grating fiber demodulation device, characterized in that: Including internal equipment and front-end equipment: Internal equipment includes a fiber-optic external interface docking station, an FPGA control chip, and a high-speed analog-to-digital converter; The optical fiber external interface expansion dock is composed of multiple parallel photoelectric converters and circuit selectors, and is provided with an optical connection status register for storing circuit status; The FPGA control chip is used to identify the number and status of connections of the fiber grating sensor unit, dynamically adjust the control signal of the circuit selector, identify the number of connections of the laser and control the laser, and perform data filtering and parallel demodulation on multi-channel analog signals; High-speed analog-to-digital converter, used to convert analog signals into digital signals; The front-end device includes a host computer and at least one fiber grating sensor unit, each of which includes a laser and its control circuit, a fiber amplifier, a splitter, an optical fiber and a circulator; The internal equipment uses time division multiplexing technology to realize the addition and deletion of fiber grating sensor units in the front-end equipment, and the architecture of the host computer and internal equipment remains unchanged during the addition and deletion process; The optical fiber external interface expansion dock is connected to the circulator of the fiber grating sensor unit through the photoelectric converter to realize the reception and selection of the optical signal; The FPGA control chip is connected to the host computer through the network port, receives control instructions from the host computer, and sends control signals to the laser.

2. The grating fiber demodulation device according to claim 1, characterized in that: The working process of the device includes: Connect the equipment, connect the laser control circuit of the fiber grating sensor unit to the laser control expansion interface of the FPGA control chip, connect the circulator of the fiber grating sensor unit to the photoelectric converter of the fiber external interface expansion dock, connect the fiber external interface expansion dock and the high-speed analog-to-digital converter to the corresponding control pins of the FPGA control chip, and connect the host computer to the network port of the FPGA control chip; Power on and activate, the FPGA control chip identifies and records the number and status of laser connections, the optical fiber external interface docking station identifies and records the number of optical path connections, and the host computer turns on and starts the system and software; Signal acquisition: The host computer sends the control instructions of the laser to the FPGA control chip through the network port. The FPGA control chip sends a sweep signal to the laser according to the status signal of the optical fiber external interface expansion dock and the control signal of the host computer. The laser emits light waves, which are transmitted and sensed through the optical fiber. The sensing light signal undergoes photoelectric conversion and path selection in the optical fiber external interface expansion dock. The high-speed analog-to-digital converter samples and converts the selected electrical signal, and transmits the converted digital signal to the FPGA control chip. Parallel control: the FPGA control chip controls the transmission of the laser and the reception of the circuit selector in a time-division multiplexing manner according to the preset control mode, thus realizing the parallel processing of multiple optical signals; Extended access: When a fiber grating sensor unit needs to be added, the laser control circuit of the newly added fiber grating sensor unit is connected to the laser control expansion interface of the FPGA control chip, and the circulator of the newly added fiber grating sensor unit is connected to the photoelectric converter of the optical fiber external interface expansion dock, and the above steps of power-on activation, signal acquisition and parallel control are repeated.

3. The grating fiber demodulation device according to claim 2, characterized in that: After power-on activation, the optical fiber external interface expansion dock identifies the connection state of the photoelectric conversion interface and stores it in the optical connection state register.

4. The grating fiber demodulation device according to claim 3, characterized in that: The FPGA control chip is connected to the optical fiber external interface expansion dock through the selector control pin, reads the optical connection status register status and transmits the circuit selector path status; the FPGA control chip transmits data of the demodulation mode and pin connection status with the host computer through the network port; the FPGA control chip sends signals to different front-end devices through time division multiplexing to perform laser scanning and sensor recognition.

5. The grating fiber demodulation device according to claim 4, characterized in that: The time division multiplexing method includes: The FPGA control chip dynamically allocates time slots to each connected fiber optic Bragg grating sensor unit according to the instructions of the host computer and the records of the optical connection status register in the optical fiber external interface expansion dock; In each time slot, the FPGA control chip controls the corresponding laser to emit a frequency-sweeping optical signal, and selects the optical signal of the corresponding fiber grating sensor unit for reception through the circuit selector in the optical fiber external interface expansion dock; The received optical signal is converted into a digital signal by a photoelectric converter and a high-speed analog-to-digital converter, and then filtered and demodulated by the FPGA control chip. When adding or deleting fiber grating sensor units, the FPGA control chip dynamically adjusts the time slot allocation according to the latest connection status.

6. The grating fiber demodulation device according to claim 5, characterized in that: The FPGA control chip receives and processes the digital signal and determines the fiber grating sensor unit to which the digital signal belongs through the clock.

7. The grating fiber demodulation device according to claim 2, characterized in that: The fiber optic external interface expansion dock performs optical-electrical conversion on the parallel selector link whose path is activated and transmits the electrical signal to the high-speed analog-to-digital converter.

8. The grating fiber demodulation device according to claim 2, characterized in that: The high-speed analog-to-digital converter obtains the electrical signal and transmits it to the filter demodulation pin of the FPGA control chip.

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