FPGA-based optical fiber vibration demodulation device and method

Abstract

The present invention discloses an optical fiber vibration demodulation device and method based on FPGA, the device comprises: an FPGA parallel processor, the FPGA parallel processor provides multiple optical fiber channels, each of the optical fiber channels comprises a pulse coding module, an ADC sampling module, a phase demodulation module and a phase merging module; the FPGA parallel processor is used to control the pulse coding modules, ADC sampling modules, phase demodulation modules and phase merging modules in multiple optical fiber channels to perform pulse coding, sampling, phase demodulation and phase merging processing respectively at the same time; the FPGA parallel processor is also used to control the pulse coding module, ADC sampling module, phase demodulation module and phase merging module in each single optical fiber channel to perform pulse coding, sampling, phase demodulation and phase merging processing respectively at the same time. The present invention realizes the parallel processing of optical fiber multi-channels and the pipeline processing of optical fiber in a single channel, thereby achieving the purpose of high-speed, long-distance and multi-channel simultaneous demodulation of optical fiber.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber vibration detection sensing technology, and in particular to an optical fiber vibration demodulation method and device based on FPGA. Background Art

[0002] Fiber optic sensing has been widely used in the field of vibration monitoring sensing due to its advantages such as high sensitivity, long monitoring distance, and good environmental tolerance. Fiber optic sensor networks have long detection distances and high spatial resolutions, and the amount of data that needs to be stored and processed is very large. The current traditional sequential processing method is to collect data through a data acquisition unit, store the collected data, and then transmit it to a data processing unit for demodulation processing. However, the storage of collected data and the data transmission between the data acquisition unit and the data processing unit have become bottlenecks for further improving the fiber optic sensing distance, sensing density, and demodulation speed.

[0003] FPGA has the advantage of parallel processing. Its huge logic resources can realize parallel processing and pipeline processing of demodulation algorithms. Therefore, it is necessary to provide a fiber optic vibration demodulation device combined with FPGA to achieve high-speed, long-distance and multi-channel demodulation of optical fiber and improve the efficiency of optical fiber demodulation. Summary of the invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies and provide an optical fiber vibration demodulation device and method based on FPGA to achieve the purpose of high-speed, long-distance and multi-channel parallel pipeline demodulation of optical fibers.

[0005] In order to achieve the above technical objectives, in a first aspect, the present invention provides an optical fiber vibration demodulation device based on FPGA, comprising an FPGA parallel processor, wherein the FPGA parallel processor provides a plurality of optical fiber channels, each of which comprises a pulse encoding module, an ADC sampling module, a phase demodulation module and a phase merging module;

[0006] The FPGA parallel processor is used to control the pulse encoding module, ADC sampling module, phase demodulation module and phase merging module in multiple optical fiber channels to perform pulse encoding, sampling, phase demodulation and phase merging processing respectively at the same time;

[0007] The FPGA parallel processor is also used to control the pulse encoding module, ADC sampling module, phase demodulation module and phase merging module in each single optical fiber channel to perform pulse encoding, sampling, phase demodulation and phase merging processing respectively at the same time.

[0008] In some embodiments, the pulse coding module is used to generate pulse coding and modulate the light source to generate coded pulse light;

[0009] The ADC sampling module is used to collect scattered signals at different spatial positions of the optical fiber based on the triggering of the electrical pulse signal;

[0010] The phase demodulation module is used to demodulate the scattered light signal to obtain scattered light phase information;

[0011] The phase merging module is used to merge the scattered light phase information by column to obtain the merged scattered light phase information.

[0012] In some embodiments, the pulse encoding module generates an encoded pulse, and the encoded pulse includes a plurality of single pulses.

[0013] In some embodiments, the time interval between two adjacent single pulse signals satisfies the following relationship: Where m is the number of pulses, T x (x is an integer greater than 0 and less than m) is the time interval between adjacent single pulses, f s is the ADC sampling rate.

[0014] In some embodiments, the ADC sampling module collects multiple groups of data through single pulse triggering, wherein the number of groups of data corresponds one-to-one to the number of optical fiber scattering signals at spatial positions.

[0015] In some embodiments, each channel of the pulse signal collected by the ADC includes three-channel information of x, y and z, wherein the three-channel information is respectively expressed by the following formulas:

[0016]

[0017]

[0018]

[0019] Among them, x(i) represents the information of the x channel, y(i) represents the information of the y channel, z(i) represents the information of the z channel, A is the amplitude, For phase.

[0020] In a second aspect, the present invention further provides an FPGA-based optical fiber vibration demodulation method, which is applied to the above-mentioned FPGA-based optical fiber vibration demodulation device, and the method comprises:

[0021] Based on the FPGA parallel processor, pulse coding, ADC signal acquisition, phase demodulation and phase merging processing are performed on the incident light in each optical fiber channel at the same time, and pulse coding, ADC signal acquisition, phase demodulation and phase merging processing are performed on the incident light in each cycle in the same optical fiber channel at the same time.

[0022] In some embodiments, the simultaneously performing pulse encoding, ADC signal acquisition, phase demodulation and phase merging processing on the incident light in each optical fiber channel includes:

[0023] At the same time, pulse encoding is performed on the incident light in each channel to obtain single pulse modulated light, and based on the single pulse modulated light, scattered signals at different spatial positions of the optical fiber are collected, and phase demodulation is performed on the first pulse in each cycle in each channel to obtain first scattered light phase information, and the first scattered light phase information is recorded in the FPGA parallel processor;

[0024] Performing phase demodulation on the second pulse to the last pulse in each cycle in each channel to obtain corresponding phase information of multiple second scattered lights;

[0025] Retrieving the first scattered light phase information in the FPGA parallel processor, and adding the first scattered light phase information to the plurality of second scattered light phase information to obtain accumulated phase information;

[0026] The accumulated phase information is post-processed to obtain post-processed phase information, and the post-processed phase information is recorded in the FPGA parallel processor, and the scattered signal of each channel optical fiber is processed in parallel based on the FPGA parallel processor.

[0027] In some embodiments, calling the first scattered light phase information in the FPGA parallel processor and adding the first scattered light phase information with the plurality of second scattered light phase information to obtain accumulated phase information includes:

[0028] Retrieving the first scattered light phase information, adding the second scattered light phase information corresponding to the second pulse to the first scattered light phase information to obtain second accumulated phase information, and recording the second accumulated phase information into the FPGA parallel processor;

[0029] Retrieving the second accumulated phase information in the FPGA parallel processor, adding the second scattered light phase information corresponding to the third pulse to the second accumulated phase information to obtain third accumulated phase information, and recording the third accumulated phase information in the FPGA parallel processor;

[0030] The third accumulated phase information in the FPGA parallel processor is retrieved, and the third accumulated phase information is added to the other second scattered light phase information to obtain accumulated phase information.

[0031] In some embodiments, the scattered light phase information can be expressed by the following formula:

[0032]

[0033] Among them, x(i) represents the information of the x channel, y(i) represents the information of the y channel, and z(i) represents the information of the z channel. is the phase information.

[0034] Compared with the prior art, the FPGA-based optical fiber vibration demodulation device and method provided by the present invention include: an FPGA parallel processor, the FPGA parallel processor provides multiple optical fiber channels, each of which includes a pulse coding module, an ADC sampling module, a phase demodulation module and a phase merging module; the FPGA parallel processor is used to control the pulse coding modules, ADC sampling modules, phase demodulation modules and phase merging modules in multiple optical fiber channels to perform pulse coding, sampling, phase demodulation and phase merging processing respectively at the same time; the FPGA parallel processor is also used to control the pulse coding module, ADC sampling module, phase demodulation module and phase merging module in each single optical fiber channel to perform pulse coding, sampling, phase demodulation and phase merging processing respectively at the same time. The device provided by the present invention is based on an FPGA parallel processor, which not only reduces the FPGA storage and transmission burden, but also supports optical fiber vibration phase demodulation of more channels and longer distances, and realizes the parallel processing of optical fiber vibration multi-channels and the pipeline processing of optical fibers in a single channel, thereby improving the efficiency of optical fiber demodulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of an embodiment of an optical fiber vibration demodulation device based on FPGA provided by the present invention;

[0036] Figure 2 It is a flow chart of an embodiment of the optical fiber vibration demodulation method based on FPGA provided by the present invention;

[0037] Figure 3 It is a timing diagram of an embodiment of FPGA parallel processing in the FPGA-based optical fiber vibration demodulation method provided by the present invention;

[0038] Figure 4 It is a flowchart of the implementation of step S203 in the FPGA-based optical fiber vibration demodulation method provided by the present invention;

[0039] Figure 5 It is a timing diagram of FPGA parallel pipeline processing in the FPGA-based optical fiber vibration demodulation method provided by the present invention;

[0040] Figure 6 It is a schematic diagram of an embodiment of FPGA data storage and transmission in the FPGA-based optical fiber vibration demodulation method provided by the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] The present invention relates to an optical fiber vibration demodulation device based on FPGA. The present invention provides an optical fiber vibration demodulation device based on FPGA. Figure 1 , comprising: an FPGA parallel processor 2, wherein the FPGA parallel processor 2 comprises a pulse encoding module 21, an ADC sampling module 22, a phase demodulation module 23 and a phase merging module 24;

[0043] The FPGA parallel processor 2 is used to control the pulse encoding module 21, ADC sampling module 22, phase demodulation module 23 and phase merging module 24 in multiple optical fiber channels to perform pulse encoding, sampling, phase demodulation and phase merging processing respectively at the same time;

[0044] The FPGA parallel processor 2 is also used to control the pulse encoding module 21, ADC sampling module 22, phase demodulation module 23 and phase merging module 24 in each single optical fiber channel to perform pulse encoding, sampling, phase demodulation and phase merging processing respectively at the same time.

[0045] In this embodiment, based on the FPGA parallel processor, pulse encoding, sampling, phase demodulation and phase merging processing are simultaneously performed on the optical fibers in multiple optical fiber channels, thereby realizing parallel processing of optical fibers, and pulse encoding, sampling, phase demodulation and phase merging processing can be simultaneously performed on the optical fibers of each period in a single optical fiber channel, thereby realizing pipeline processing of optical fibers. Furthermore, based on the FPGA parallel processor, the amount of data storage and transmission is reduced, thereby realizing high-speed and long-distance demodulation of optical fibers.

[0046] In some embodiments, the pulse coding module is used to generate pulse coding and modulate the light source 1 to generate coded pulse light;

[0047] The ADC sampling module 22 is used to collect scattered signals at different spatial positions of the optical fiber based on the triggering of the electrical pulse signal;

[0048] The phase demodulation module 23 is used to demodulate the scattered light signal to obtain scattered light phase information;

[0049] The phase merging module 24 is used to merge the scattered light phase information by column to obtain the merged scattered light phase information;

[0050] The FPGA parallel processor 2 is used to perform pulse encoding, sampling, phase demodulation and phase merging processing on multiple channel data simultaneously, and is used to store the scattered light phase information and the merged scattered light phase information.

[0051] In the embodiment of the present invention, based on the FPGA parallel processor, the light of the light source 1 is first modulated by the pulse coding module 21, and then the modulated light signal is sampled by the ADC sampling module 22 to obtain scattered signals at different spatial positions. Furthermore, the phase demodulation module 23 is used to demodulate the obtained scattered signal to obtain scattered light phase information, and the first scattered light phase information obtained in each cycle is stored in the memory of the FPGA, and then the addition and merging module 24 is used to merge the scattered light phase information by column to obtain merged scattered light phase information, and the scattered light signal in the cycle is processed, and the processed scattered light phase information is stored in the FPGA, and the signals of multiple channels are processed in parallel at the same time by the FPGA, which not only reduces the storage and transmission burden of the FPGA, but also supports optical fiber vibration phase demodulation of more channels and longer distances, and realizes parallel processing and pipeline processing of optical fiber demodulation.

[0052] In some embodiments, the FPGA parallel processor 2 is used to control the pulse encoding module, ADC sampling module, phase demodulation module and phase merging module in the same channel to simultaneously perform corresponding pipeline processing operations on the scattered signals.

[0053] In this embodiment, based on the FPGA parallel processor, acquisition and demodulation operations are performed simultaneously, parallel pipeline processing between modules is realized, and the efficiency of optical fiber demodulation is improved.

[0054] In some embodiments, a 3×3 coupler is further included, wherein the 3×3 coupler is used to receive a signal scattered in the optical fiber and divide the scattered signal into three scattered light signals.

[0055] In some embodiments, the pulse encoding module generates a coded pulse, and the coded pulse includes multiple single pulses. First, the light source is modulated by a pulse encoder, and the coded pulse is composed of m single pulses. The time intervals between adjacent single pulses are Tx (x is an integer greater than 0 and less than m), and the following relationship is satisfied: Wherein, fs is the ADC sampling rate, and m is an integer greater than or equal to 4.

[0056] Furthermore, the preset ADC acquisition method uses a single pulse trigger to collect n groups of data (each group of data corresponds to the fiber scattering signal at a different spatial position) through the ADC sampling module. The coded pulse of each cycle is composed of m single pulses, and each channel corresponds to 3 signals. Each channel needs to collect m×n×3 data in one cycle. Among them, x, y, and z are the 3 signals of each channel, the amplitudes of the 3 signals are all equal to A, and the phase difference of the 3 signals is equal to 120°, which is specifically expressed as follows:

[0057]

[0058] Pulse 1: {x 11 ,x 12 ,……,x 1n},{y 11 ,y 12 ,……,y 1n},{z 11 ,z 12 ,……,z 1n}

[0059] Pulse 2: { 21 ,x 22 ,……,x 2n},{y 21 ,y 22 ,……,y 2n},{z 21 ,z 22 ,……,z 2n}

[0060] Pulse m: { m1 ,x m2 ,……,x mn},{y m1 ,y m2 ,……,y mn},{z m1 ,z m2 ,……,z mn}

[0061] The FPGA-based optical fiber vibration demodulation method involved in the present invention can simultaneously perform parallel processing and pipeline processing on signals of multiple cycles of multiple channels. Specifically, based on the FPGA parallel processor, pulse encoding, ADC signal acquisition, phase demodulation and phase merging processing are performed on the incident light in each optical fiber channel at the same time, and pulse encoding, ADC signal acquisition, phase demodulation and phase merging processing are performed on the incident light in each cycle in the same optical fiber channel at the same time.

[0062] In some embodiments, see Figure 2, the pulse encoding, ADC signal acquisition, phase demodulation and phase merging processing of the incident light in each optical fiber channel are performed simultaneously, including:

[0063] S201, pulse encoding the incident light in each channel at the same time to obtain single pulse modulated light, based on the single pulse modulated light, collecting scattered signals at different spatial positions of the optical fiber, performing phase demodulation on the first pulse in each cycle in each channel to obtain first scattered light phase information, and recording the first scattered light phase information into the FPGA parallel processor;

[0064] S202, performing phase demodulation from the second pulse to the last pulse in each cycle in each channel to obtain corresponding phase information of multiple second scattered lights;

[0065] S203, calling the first scattered light phase information in the FPGA parallel processor, and adding the first scattered light phase information to the plurality of second scattered light phase information to obtain accumulated phase information;

[0066] S204, post-processing the accumulated phase information to obtain post-processing phase information, and recording the post-processing phase information in the FPGA parallel processor, and performing parallel processing on the scattered signal of each channel optical fiber based on the FPGA parallel processor.

[0067] In this embodiment, firstly, the first pulse in each cycle of multiple channels is phase demodulated to obtain first scattered light phase information, and the first scattered light phase information is recorded in the FPGA. Then, the second pulse to the last pulse in each cycle are phase demodulated to obtain corresponding multiple second scattered light phase information. Finally, the first scattered light phase information is added to the multiple second scattered light phase information, and the mean phase information is obtained, and the mean phase information is recorded in the FPGA. Only one mean phase information needs to be stored in each cycle of each channel, and during data transmission, the phase information state of the current cycle of the channel can be represented by the mean phase information, which reduces the storage and transmission burden of the FPGA, can support more channels and longer distances of optical fiber vibration phase demodulation, realize high-speed demodulation of optical fiber vibration, and realize parallel processing of multiple channels through FPGA, thereby improving the efficiency of phase demodulation.

[0068] It should be noted that the post-processing method includes averaging the data, specifically, averaging the accumulated phase information to obtain mean phase information, and recording the mean phase information into the FPGA; the post-processing method also includes filtering the data, specifically, filtering the accumulated phase information to obtain filtered phase information, and recording the filtered phase information into the FPGA.

[0069] For further information, see Figure 3 ,Parallel processing means that multiple channels simultaneously perform phase demodulation of fiber pulses.

[0070] In some embodiments, see Figure 4 and Figure 5 , calling the first scattered light phase information in the FPGA, and adding the first scattered light phase information with the plurality of second scattered light phase information to obtain accumulated phase information, including:

[0071] S401, calling the first scattered light phase information, adding the second scattered light phase information corresponding to the second pulse to the first scattered light phase information to obtain second accumulated phase information, and recording the second accumulated phase information into the FPGA;

[0072] S402, calling the second accumulated phase information in the FPGA, adding the second scattered light phase information corresponding to the third pulse to the second accumulated phase information to obtain third accumulated phase information, and recording the third accumulated phase information in the FPGA;

[0073] S403, retrieve the third accumulated phase information in the FPGA, add the third accumulated phase information to other second scattered light phase information, and obtain accumulated phase information.

[0074] In this embodiment, each channel of each cycle simultaneously performs pulse encoding, sampling, phase demodulation and phase merging operations, wherein the first scattered light phase information obtained after phase demodulation of the first pulse signal in each cycle is recorded in the FPGA, and then the second scattered light phase information obtained from the second pulse signal after demodulation is added to the first scattered light phase information, and the result of the addition is recorded in the FPGA for temporary storage, and finally the results of phase demodulation of subsequent pulse signals in the same cycle are sequentially added to the results stored in the FPGA for the previous time, and when the last pulse signal in the cycle is reached, the result after phase demodulation is added to the result stored in the FPGA for the previous time, and finally the accumulated result is averaged to obtain the mean phase, and the final mean phase is recorded in the FPGA as a phase information state characterization signal of the current channel and the current cycle.

[0075] In some embodiments, phase demodulation is performed on the data sampled and collected by the ADC to demodulate the phase information of the scattered light at the optical fiber sampling point. The phase information can be expressed by the following formula:

[0076]

[0077] Among them, x(i) represents the information of the x channel, y(i) represents the information of the y channel, and z(i) represents the information of the z channel. is the phase information.

[0078] In this embodiment, for the continuous functions x, y, z, the following conditions are satisfied:

[0079]

[0080] From this we can see that:

[0081]

[0082] By adding (2)+(3), we can get:

[0083]

[0084] Formula (2)-(3) gives:

[0085]

[0086] Similarly, we can get:

[0087]

[0088]

[0089] Similarly, we can get:

[0090]

[0091]

[0092] In summary, formulas (4)-(6) yield:

[0093]

[0094]

[0095] Formula (8) / (10) yields:

[0096]

[0097] The phase is resolved to:

[0098]

[0099] Furthermore, according to the data collected by the ADC sampling module 2, the corresponding optical fiber phase information is calculated as follows:

[0100] Pulse 1:

[0101] Pulse 2:

[0102] …

[0103] Pulse m:

[0104]

[0105]

[0106] …

[0107]

[0108] It should be noted that the first scattered light phase information and the plurality of second scattered light phase information are added by using a column addition method.

[0109] In some embodiments, the mean phase information may be expressed by the following formula:

[0110]

[0111] Where m represents the number of pulses in each cycle, n represents the amount of data collected, Indicates the nth phase information corresponding to the mth second pulse, Represents the mean phase information.

[0112] The phase information obtained after phase demodulation is merged by column, and the merged data is as follows:

[0113]

[0114]

[0115]

[0116] …

[0117]

[0118] In a specific embodiment, the length of the optical fiber is 10 km, and the light source is modulated by generating coded pulses (the pulse light of the light source is injected into the optical fiber, and the signal light scattered back from the optical fiber is reflected by the Faraday rotator and then output as three signals through a 3×3 coupler, the amplitudes of the three signals are equal, and the phase differences of the three signals are all equal to 120°), the coded pulse is composed of 10 single pulses, and the time intervals of adjacent single pulses are respectively Tx (x is an integer greater than 0 and less than 10), and the following relationship is satisfied:

[0119]

[0120] Wherein fs=200MHz is the ADC sampling rate.

[0121] The ADC sampling module is triggered by a single pulse to sample n groups of data at 200MHz (each group of data corresponds to the fiber scattering signal at a spatial position 0.5m apart). Each cycle of the coded pulse consists of 10 single pulses, each channel corresponds to 3 signals, and each channel needs to collect 10×20000×3 data in one cycle. Among them, x, y, and z are the 3 signals of each channel, the amplitude of the 3 signals is equal to A, and the phase difference of the 3 signals is equal to 120°.

[0122]

[0123]

[0124]

[0125] Pulse 1: {x 1-1 ,x 1-2 ,……,x 1-20000},{y 1-1 ,y 1-2 ,……,y 1-20000},{z 1-1 ,z 1-2 ,……,z 1-20000}

[0126] Pulse 2: {x 2-1 ,x 2-2 ,……,x 2-20000},{y 2-1 ,y 2-2 ,……,y 2-20000},{z 2-1 ,z 22 ,……,z 2-20000}

[0127] …

[0128] Pulse 10: {x 10-1 ,x 10-2 ,……,x 10-20000},{y 10-1 ,y 10-2 ,……,y 10-20000},{z 10-1 ,z 10-2 ,……,z 10-20000}

[0129] The data corresponding to pulse 1 are the optical fiber scattering signals at the spatial positions of 0.5m, 1m, 1.5m, ..., 10km; the data corresponding to pulse 2 are the optical fiber scattering signals at the spatial positions of 0.45m, 0.95m, 1.45m, ..., 9999.95m; the data corresponding to pulse m are the optical fiber scattering signals at the spatial positions of 0.05m, 0.55m, 1.05m, ..., 9999.05m.

[0130] By performing phase demodulation on the data collected by ADC sampling, the scattered light phase information of the fiber sampling point is demodulated. The change in the phase of the fiber scattered light can directly reflect the vibration of the fiber. For continuous functions x, y, z, the following conditions are met:

[0131]

[0132] According to formulas 1, 2 and 4, the following results can be derived:

[0133]

[0134]

[0135] Formula ⑸+⑸, we can get:

[0136]

[0137] Formula ⑸-⑸, we can get:

[0138]

[0139] According to formulas 1, 3 and 4, we can get:

[0140]

[0141]

[0142] According to formula 2, 3 and 4, we can get:

[0143]

[0144]

[0145] In summary, formula ⑺-⑼, we can get:

[0146]

[0147]

[0148] Formula (11) / (13) yields:

[0149]

[0150] The phase is resolved to:

[0151]

[0152] According to the data collected by ADC sampling, the corresponding optical fiber phase information is calculated as follows:

[0153] Pulse 1:

[0154] Pulse 2:

[0155] …

[0156] Pulse 10:

[0157]

[0158]

[0159] …

[0160]

[0161] By merging the phase information after phase demodulation by column, the merged data is as follows:

[0162]

[0163]

[0164]

[0165] …

[0166]

[0167] Each cycle will simultaneously perform multi-channel pulse encoding, ADC sampling, phase demodulation, and phase merging operations. The phase demodulation result of the first single pulse in each cycle will be written into the FIFO; the 2nd to m-1st, i.e., the 2nd to 9th single pulses will read the phase result of the previous single pulse in this cycle from the FIFO, and accumulate the phase result of the phase demodulation of the current single pulse and the phase result of the previous single pulse, and write the accumulated phase result into the FIFO; the m=10th single pulse will read the phase result of the previous single pulse in this cycle from the FIFO, and accumulate and average the phase demodulation result of the current single pulse and the phase result of the previous single pulse, and write the averaged phase result into the FIFO, thus realizing the pipeline processing of optical fiber phase demodulation. Since phase demodulation and phase merging use the same FIFO, and phase merging will write an accumulated or averaged phase result after reading a phase result, the maximum FIFO data storage capacity of each channel is n=20000. Please refer to Figure 6 If the traditional sequential processing method is used, each channel of the ADC sampling acquisition needs to be stored and transmitted to the data processing unit for m×n×3=10×20000×3 data to perform phase demodulation and phase merging operations. However, using FPGA parallel pipeline processing, the amount of phase demodulation and merging results that need to be stored in each channel is n=20000, and only the merged phase demodulation results of each channel need to be stored. Compared with the traditional sequential processing method, the data storage and transmission volume of each channel in each cycle is reduced from the original m×n×3=10×20000×3 to n=20000, and the data storage and transmission volume is reduced by 3m=30 times, which greatly reduces the FPGA storage and transmission burden, and can support more channels and longer distances of optical fiber vibration phase demodulation, realizing high-speed demodulation of optical fiber vibration.

[0168] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An optical fiber vibration demodulation device based on FPGA, characterized in that: include: An FPGA parallel processor, wherein the FPGA parallel processor provides a plurality of optical fiber channels, each of which includes a pulse encoding module, an ADC sampling module, a phase demodulation module, and a phase merging module; The FPGA parallel processor is used to control the pulse encoding module, ADC sampling module, phase demodulation module and phase merging module in multiple optical fiber channels to perform pulse encoding, sampling, phase demodulation and phase merging processing respectively at the same time; The FPGA parallel processor is also used to control the pulse encoding module, ADC sampling module, phase demodulation module and phase merging module in each single optical fiber channel to perform pulse encoding, sampling, phase demodulation and phase merging processing respectively at the same time; The FPGA parallel processor is also used to simultaneously pulse encode the incident light in each channel to obtain single pulse modulated light, collect scattered signals at different spatial positions of the optical fiber based on the single pulse modulated light, perform phase demodulation on the first pulse in each cycle in each channel to obtain first scattered light phase information, and record the first scattered light phase information in the FPGA parallel processor; Phase demodulation is performed on the second pulse to the last pulse in each cycle in each channel to obtain corresponding multiple second scattered light phase information; the first scattered light phase information in the FPGA parallel processor is retrieved, and the first scattered light phase information is added to the multiple second scattered light phase information to obtain accumulated phase information; the accumulated phase information is post-processed to obtain post-processed phase information, and the post-processed phase information is recorded in the FPGA parallel processor, and the scattered signal of each channel optical fiber is processed in parallel based on the FPGA parallel processor; and pulse encoding, ADC signal acquisition, phase demodulation and phase merging processing are simultaneously performed on the incident light in each cycle in the same optical fiber channel.

2. The optical fiber vibration demodulation device based on FPGA according to claim 1, characterized in that: The pulse coding module is used to generate pulse coding and modulate the light source to obtain coded pulse light; The ADC sampling module is used to collect scattered signals at different spatial positions of the optical fiber based on the triggering of the electrical pulse signal; The phase demodulation module is used to demodulate the scattered light signal to obtain scattered light phase information; The phase merging module is used to merge the scattered light phase information by column to obtain the merged scattered light phase information.

3. The FPGA-based optical fiber vibration demodulation device according to claim 2, characterized in that: The coded pulse light includes a plurality of single pulse lights.

4. The FPGA-based optical fiber vibration demodulation device according to claim 3, characterized in that: The time interval between two adjacent single pulse signals satisfies the following relationship: , where m is the number of pulses, T x (x is an integer greater than 0 and less than m) is the time interval between adjacent single pulses, f s is the ADC sampling rate.

5. The optical fiber vibration demodulation device based on FPGA according to claim 3, characterized in that: The ADC sampling module collects multiple groups of data through single pulse triggering, wherein the number of groups of data corresponds one-to-one to the number of optical fiber scattering signals at spatial positions.

6. The optical fiber vibration demodulation device based on FPGA according to claim 5, characterized in that: Each channel of the pulse signal collected by the ADC includes three-channel information of x, y and z, wherein the three-channel information is expressed by the following formulas respectively: ， ， ， in, Represents the information of the x channel, Represents the information of the y channel, Represents the information of the z channel, A is the amplitude, For phase.

7. An optical fiber vibration demodulation method based on FPGA, applied to the optical fiber vibration demodulation device based on FPGA according to any one of claims 1 to 6, characterized in that: The method comprises: Based on the FPGA parallel processor, pulse encoding is performed on the incident light in each channel at the same time to obtain single pulse modulated light. Based on the single pulse modulated light, scattered signals at different spatial positions of the optical fiber are collected, and phase demodulation is performed on the first pulse in each cycle in each channel to obtain first scattered light phase information, and the first scattered light phase information is recorded in the FPGA parallel processor; phase demodulation is performed on the second pulse to the last pulse in each cycle in each channel to obtain corresponding multiple second scattered light phase information; the first scattered light phase information in the FPGA parallel processor is retrieved, and the first scattered light phase information is added to the multiple second scattered light phase information to obtain accumulated phase information; the accumulated phase information is post-processed to obtain post-processed phase information, and the post-processed phase information is recorded in the FPGA parallel processor, and the scattered signals of each channel optical fiber are processed in parallel based on the FPGA parallel processor; and pulse encoding, ADC signal acquisition, phase demodulation and phase merging processing are performed on the incident light in each cycle in the same optical fiber channel at the same time.

8. The optical fiber vibration demodulation method based on FPGA according to claim 7, characterized in that: The step of retrieving the first scattered light phase information in the FPGA parallel processor and adding the first scattered light phase information to the plurality of second scattered light phase information to obtain accumulated phase information includes: Retrieving the first scattered light phase information, adding the second scattered light phase information corresponding to the second pulse to the first scattered light phase information to obtain second accumulated phase information, and recording the second accumulated phase information into the FPGA parallel processor; Retrieving the second accumulated phase information in the FPGA parallel processor, adding the second scattered light phase information corresponding to the third pulse to the second accumulated phase information to obtain third accumulated phase information, and recording the third accumulated phase information in the FPGA parallel processor; The third accumulated phase information in the FPGA parallel processor is retrieved, and the third accumulated phase information is added to the other second scattered light phase information to obtain the accumulated phase information.

9. The optical fiber vibration demodulation method based on FPGA according to claim 8, characterized in that: The scattered light phase information can be expressed by the following formula: , in, Represents the information of the x channel, Represents the information of the y channel, Represents the information of the z channel, is the phase information.

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