Method and system for storing and reading detection data for phase-sensitive optical time-domain reflectometry

Abstract

The present invention relates to a detection data storage and reading method and system for a phase-sensitive optical time-domain reflectometer. The method comprises: first, extracting the main lobe of the spectrum of the detection signal of the backscattered Rayleigh light generated by the optical fiber to be tested; second, sampling the signal retaining only the main lobe of the spectrum at a low sampling rate and / or low resolution, and storing it in a preset database; then, retrieving the corresponding data in the database according to the received query instruction, converting the resolution of the corresponding data and restoring the signal waveform before sampling; then, performing phase demodulation on the data after the resolution conversion and signal waveform restoration to obtain sensing information in the form of a two-dimensional space-time matrix. The present invention has ultra-high compression efficiency, greatly increasing the amount of data that can be stored on a hard disk of the same specification, extending the monitoring time that the system can save, and at the same time maintaining the dense sampling points of the phase demodulation results on the distance axis, preserving the data characteristics to the greatest extent.

Description

Technical Field

[0001] The present invention relates to the field of data processing technology, and in particular to a detection data storage and reading method and system for a phase-sensitive optical time-domain reflectometer. Background Art

[0002] Phase-sensitive distributed fiber optic sensing systems enable large-scale, wide-area distributed disturbance or strain sensing. They continuously emit pulsed light into the sensing fiber. As these pulsed light propagates forward through the fiber, they generate scattered light traveling backward. By collecting and demodulating this backscattered light, strain information along the fiber can be obtained, enabling long-distance sensing. Typically, this sensing system generates a massive amount of sensor data.

[0003] There are currently two data storage solutions. The first storage solution is to directly store the raw data, then read in the raw data and perform phase demodulation to obtain sensor information. The second storage solution is to directly process the data and demodulate the phase results to obtain two-dimensional sensor information. After that, the sensor information is downsampled in the spatial axis dimension to reduce the amount of data that needs to be stored.

[0004] The first storage solution can only store short-term data. For example, if a data acquisition card collects beat frequency signals at a sampling rate of 250MSa / s and a 16-bit sampling resolution, the data volume per second is as high as 476.84MB. This data volume is obviously not enough to store long-term monitoring data.

[0005] The second storage solution has a flaw: it downsamples the spatial axis of the phase demodulation results based on system resolution. In geological exploration, maintaining dense sampling points along the distance axis is often necessary to better analyze sensor information. However, due to the spatial downsampling, this data storage solution cannot meet the requirements of geological exploration. Furthermore, this data storage solution stores downsampled phase information, with a sampling rate of typically 10 to 20 MSa / s and a sampling accuracy of 14 to 16 bits. Consequently, the amount of sensor data generated per second is approximately 16.69 to 38.15 MB. This data volume remains a significant challenge for distributed sensing systems requiring long-term monitoring. Summary of the Invention

[0006] (1) Technical issues to be resolved

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a detection data storage and reading method and system for a phase-sensitive optical time-domain reflectometer, which solves the technical problems that the existing storage scheme cannot store long-term backscattered Rayleigh scattered light monitoring data and cannot retain more data features.

[0008] (2) Technical solution

[0009] In order to achieve the above objectives, the main technical solutions adopted by the present invention include:

[0010] In a first aspect, an embodiment of the present invention provides a detection data storage method for a phase-sensitive optical time-domain reflectometer, comprising:

[0011] Extracting the main lobe of the spectrum of the detection signal of the backscattered Rayleigh light generated by the optical fiber to be tested;

[0012] The signal with only the main lobe of the spectrum retained is sampled at a low sampling rate and / or low resolution and stored in a preset database.

[0013] Optionally, performing spectrum main lobe extraction on the acquired detection signal of the backscattered Rayleigh light generated by the optical fiber to be tested includes:

[0014] Acquire the detection signal of the backscattered Rayleigh light generated by the optical fiber under test when the signal is transmitted;

[0015] Extracting the main lobe of the spectrum of the detection signal through a first filter, and filtering out noise outside the main lobe of the spectrum;

[0016] The detection signal is a beat frequency signal composed of several groups of continuous signals and is a one-dimensional signal. The center frequency of the first filter is f c The same as the center frequency of the beat signal, and the bandwidth B of the first filter and the pulse width T of the detection pulse P Satisfies: B = 2 / T p .

[0017] Optionally, sampling the signal retaining only the main lobe of the spectrum at a low sampling rate and / or low resolution, and storing the sample in a preset database includes:

[0018] At a low sampling rate f s The signal retaining only the main lobe of the spectrum is sampled, and the low sampling rate satisfies the following relationship:

[0019] 2f U / m≤f S ≤2f L / (m-1),

[0020] Where, f U is the high cutoff frequency of the beat signal, f U =f C +B / 2;f L is the low cutoff frequency of the beat signal, f L =f C -B / 2; m is an integer, 1≤m≤f U / B;

[0021] and / or,

[0022] The signal retaining only the main lobe of the spectrum is sampled with a low sampling resolution r, and the value range of r is 1 to 7 bits;

[0023] After sampling the signal retaining only the main lobe of the spectrum at a low sampling rate and / or low resolution, removing invalid data at the end of each group of continuous signals retaining only the main lobe of the spectrum;

[0024] According to the storage switch state of the preset database, the signal with only the main lobe of the spectrum removed and the invalid data at the end is stored in the preset database or called to a corresponding display device for display.

[0025] Optionally, according to the storage switch state of the preset database, the signal with only the main lobe of the spectrum removed from the end of the invalid data is stored in the preset database or called to a corresponding display device for display, including:

[0026] When the storage switch of the database is turned on, the signal currently temporarily stored in the buffer zone with only the main lobe of the spectrum removed from the end of the signal is stored in the preset database;

[0027] When the storage switch of the database is not turned on, determining whether the display switch of the display device is turned on;

[0028] If the display switch is on, phase demodulation is performed on the signal temporarily stored in the buffer with only the main lobe of the spectrum removed from the end of the invalid data, and the phase demodulation result is displayed on the display device;

[0029] The data not stored in the preset database all exists in the buffer zone.

[0030] In a second aspect, an embodiment of the present invention provides a method for reading detection data for a phase-sensitive optical time-domain reflectometer, comprising:

[0031] Retrieving corresponding data from the database according to the received query instruction, converting the resolution of the corresponding data and restoring the signal waveform before sampling;

[0032] Phase demodulation is performed on the data after the resolution is converted and the signal waveform is restored to obtain sensing information in the form of a two-dimensional space-time matrix.

[0033] Optionally, retrieving corresponding data from a database according to the received query instruction, converting the resolution of the corresponding data, and restoring the signal waveform before sampling includes:

[0034] Upon receiving a query instruction for stored data, retrieve the corresponding data in the database according to the query instruction;

[0035] Converting the retrieved corresponding data into a different resolution, and restoring the signal waveform before sampling through a second filter;

[0036] Wherein, the center frequency f' of the second filter C Satisfies: f` C =|f C -k*f s |, k is a positive integer.

[0037] In a third aspect, an embodiment of the present invention provides a high storage efficiency distributed optical fiber sensing system, comprising: an optical sensor module and a data processing module for executing the method described above and the method described above;

[0038] The optical sensing module includes: a laser transmitter, a first optical fiber coupler, an acousto-optic modulator, a first optical amplifier, a first circulator, a sensing optical cable, a second optical amplifier, a second optical fiber coupler and a balanced photodetector;

[0039] The laser transmitter is used to send continuous laser light to the first optical fiber coupler;

[0040] The first fiber coupler is used to split the continuous laser light into two identical light paths, one continuous laser light path is used to be sent to the acousto-optic modulator, and the other continuous laser light path is used to be sent to the second fiber coupler;

[0041] The acousto-optic modulator is used to modulate the received continuous laser light into pulsed light through a driving signal, and send the pulsed light to the first optical amplifier;

[0042] The first optical amplifier is used to amplify the pulse light and send it to the first circulator;

[0043] The first circulator is used to send the amplified pulsed light to the sensor optical cable, and is also used to receive the backscattered Rayleigh light returned by the sensor optical cable and send it to the second optical amplifier;

[0044] The second optical amplifier is used to amplify the Rayleigh backscattered light and send it to the second circulator;

[0045] The second circulator sends the amplified Rayleigh backscattered light to a second fiber coupler;

[0046] The second optical fiber coupler is used to beat the filtered back Rayleigh scattered light of the noise with another continuous laser, and send the obtained beat signal in the form of light to a balanced photodetector;

[0047] The balanced photodetector is used to convert the beat frequency signal in optical form into a beat frequency signal in electrical form and send the signal to the data processing module.

[0048] Optionally, an optical isolator for isolating echo light is further provided between the laser emitter and the first optical fiber coupler; and the laser emitter is a narrow linewidth laser, and the first optical amplifier and the second optical amplifier are both erbium-doped fiber amplifiers.

[0049] Optionally, the system further comprises: a fiber Bragg grating filter connected to the second port of the second circulator;

[0050] The fiber Bragg grating filter is used to filter out the spontaneous emission noise of the amplified Rayleigh backscattered light, and send the filtered Rayleigh backscattered light with noise to the second fiber coupler.

[0051] Optionally, the data processing module includes: a first filter, a data acquisition card, a processor, a storage medium, a second filter and an IQ phase demodulation module;

[0052] The first filter is used to extract the main lobe of the spectrum of the electrical beat frequency signal and filter out noise outside the main lobe of the spectrum;

[0053] The data acquisition card is used to sample the signal retaining only the main lobe of the spectrum at a low sampling rate and / or low resolution, and store the sample in the storage medium;

[0054] The processor is used to retrieve corresponding data from the storage medium according to the received query instruction, and convert the resolution of the corresponding data to a required resolution;

[0055] The second filter is used to restore the data converted to the required resolution to the signal waveform before sampling;

[0056] The IQ phase demodulation module is used to perform IQ phase demodulation on the data after the resolution is converted and the signal waveform is restored, so as to obtain sensing information in the form of a two-dimensional space-time matrix.

[0057] (3) Beneficial effects

[0058] The beneficial effects of the present invention are as follows: Compared to existing solutions, this solution extracts the main lobe of the data spectrum and then samples the data at a low sampling rate and low resolution. Therefore, expensive specialized data acquisition equipment is not required to complete data sampling, significantly reducing the cost of data acquisition equipment. Furthermore, the amount of data generated per second using this low sampling rate and low sampling resolution is far lower than the amount of data required to store phase results in existing solutions. Therefore, this solution has ultra-high compression efficiency, significantly increasing the amount of data that can be stored on a hard drive of the same specifications, extending the system's survivable monitoring time, and simultaneously maintaining dense sampling points of the phase demodulation results on the range axis, preserving data characteristics to the greatest extent possible. This approach has significant promotional and practical application significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A schematic flow chart of a detection data storage method for a phase-sensitive optical time-domain reflectometer provided by the present invention;

[0060] Figure 2 A schematic diagram of a specific flow chart of step S1 of a detection data storage method for a phase-sensitive optical time-domain reflectometer provided by the present invention;

[0061] Figure 3 A schematic diagram of a specific flow chart of step S2 of a detection data storage method for a phase-sensitive optical time-domain reflectometer provided by the present invention;

[0062] Figure 4 A schematic diagram of a specific judgment process of step S24 of a detection data storage method for a phase-sensitive optical time-domain reflectometer provided by the present invention;

[0063] Figure 5 A schematic diagram of the process of calling and demodulating data stored in a database in a detection data storage method for a phase-sensitive optical time-domain reflectometer provided by the present invention;

[0064] Figure 6 A schematic diagram of a specific flow chart of step S3 of a detection data reading method for a phase-sensitive optical time-domain reflectometer provided by the present invention;

[0065] Figure 7 (a), (b) and (c) are respectively the data processing flow for directly storing original data, the data processing flow for storing phase demodulation results at a low sampling rate and the data processing flow for storing original data at a low sampling rate and low resolution provided by the present invention;

[0066] Figure 8 A schematic diagram of the composition of a high storage efficiency distributed optical fiber sensing system provided by the present invention.

[0067] [Description of Reference Numerals]

[0068] 1: Optical sensor module; 101: Narrow linewidth laser; 102: Optical isolator; 103: First fiber coupler; 104: Acousto-optic modulator; 105: Erbium-doped fiber amplifier 1; 106: First circulator; 10601: First port of the first circulator; 10602: Second port of the first circulator; 10603: Third port of the first circulator; 107: Sensing cable; 108: Second Erbium-doped fiber amplifier; 109: Second circulator; 10902: First port of the second circulator; 10902: Second port of the second circulator; 10903: Third port of the second circulator; 110: Fiber Bragg grating filter; 111: Second fiber coupler; 112: Balanced photodetector;

[0069] 2: Data processing module; 201: First filter; 202: Data acquisition card; 203: Storage medium; 204: IQ phase demodulation module; 205: Display device; 206: Second filter. DETAILED DESCRIPTION

[0070] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0071] like Figure 1 As shown, an embodiment of the present invention proposes a detection data storage method for a phase-sensitive optical time-domain reflectometer, comprising: first, extracting the main lobe of the spectrum of the detection signal of the back-Rayleigh scattered light generated by the optical fiber to be tested; second, sampling the signal retaining only the main lobe of the spectrum at a low sampling rate and / or low resolution, and storing it in a preset database.

[0072] Compared to existing solutions, this solution extracts the main lobe of the data spectrum and then samples the data at a low sampling rate and resolution. Therefore, it eliminates the need for expensive, specialized data acquisition equipment to complete data sampling, significantly reducing the cost of data acquisition equipment. Furthermore, the low sampling rate and resolution used in this invention generate far less data per second than the amount of data required to store phase results in existing solutions. This results in ultra-high compression efficiency, significantly increasing the amount of data that can be stored on a hard drive of the same specifications and extending the system's monitoring time. It also maintains dense sampling points for the phase demodulation results along the range axis, preserving data characteristics to the greatest extent possible, thus possessing significant promotional and practical application significance.

[0073] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0074] Specifically, an embodiment of the present invention provides a detection data storage method for a phase-sensitive optical time-domain reflectometer, which includes:

[0075] S1. Extracting the main lobe of the spectrum of the detection signal of the backscattered Rayleigh light generated by the optical fiber to be tested.

[0076] Furthermore, if Figure 2 As shown, step S1 includes:

[0077] S11. Acquire a detection signal of backscattered Rayleigh light generated by the optical fiber to be tested when the optical fiber sends a signal.

[0078] S12. Extract the main lobe of the spectrum of the detection signal through a first filter, and filter out noise outside the main lobe of the spectrum.

[0079] In step S1, the function of the first filter is to filter out the noise except the main lobe of the signal in the signal spectrum so as to facilitate the subsequent sampling. The filter has two key parameters: the center frequency f of the filter and the c , the second is the bandwidth of the filter B. The center frequency f of the first filter is c The bandwidth B of the first filter is generally set to be slightly larger than the bandwidth of the beat frequency signal, and the bandwidth B of the first filter is the same as the center frequency of the scattered light beat frequency signal (which is also equal to the frequency shift introduced by the modulator in the conventional Φ-OTDR optical fiber system). P Satisfies: B = 2 / T p Preferably, the first filter is a bandpass filter.

[0080] S2. Sample the signal with only the main lobe of the spectrum retained at a low sampling rate and / or low resolution, and store the sample in a preset database.

[0081] Furthermore, if Figure 3 As shown, step S2 includes:

[0082] S21, with low sampling rate f s Sampling the signal that only retains the main lobe of the spectrum, and the low sampling rate f s Satisfies the following relationship:

[0083] 2f U / m≤f S ≤2f L / (m-1),

[0084] Where, f U is the high cutoff frequency of the beat signal, f U =f C +B / 2;f L is the low cutoff frequency of the beat signal, f L =f C -B / 2; m is an integer, 1≤m≤f U / B. When sampling, the low sampling rate can be determined according to the relationship of the bandpass sampling theorem above;

[0085] and / or,

[0086] S22. Sample the signal retaining only the main lobe of the spectrum at a low sampling resolution r, where r ranges from 1 to 7 bits. Low sampling resolution refers to sampling the data at a sampling resolution of 1 to 7 bits. Sampling the data at a low sampling rate and low sampling resolution can significantly reduce the data size, thereby achieving data compression.

[0087] S23 . After sampling the signal with only the main lobe of the spectrum retained at a low sampling rate and / or low resolution, remove invalid data at the end of each group of continuous signals of the signal with only the main lobe of the spectrum retained.

[0088] S24. Based on the storage switch status of the preset database, the signal, which removes the invalid data at the end and retains only the main lobe of the spectrum, is stored in the preset database or retrieved for display on a corresponding display device. The collected compressed data is then stored on a storage medium such as a hard disk or displayed on a display device. Note that the compressed raw data is stored here, not the phase demodulation result.

[0089] Furthermore, if Figure 4 As shown, step S24 includes:

[0090] S241. At a certain moment, a section of signal data with only the main lobe of the spectrum removed from the end is stored in the buffer, and it is determined whether the storage switch of the database is turned on.

[0091] S242a. When the storage switch of the database is turned on, the signal currently temporarily stored in the buffer area with only the main lobe of the spectrum removed from the end is stored in the preset database.

[0092] S242b: When the storage switch of the database is not turned on, determine whether the display switch of the display device is turned on.

[0093] S243: If the display switch is on, phase demodulation is performed on the signal temporarily stored in the buffer, with only the main lobe of the spectrum removed from the invalid data at the end, and the phase demodulation result is displayed on the display device. If the display switch is not on, the process returns to step S241. Data not stored in the preset database is stored in the buffer.

[0094] Furthermore, the present invention provides a method for reading detection data of a phase-sensitive optical time-domain reflectometer, comprising:

[0095] S3. Retrieve the corresponding data from the database according to the received query instruction, convert the resolution of the corresponding data and restore the signal waveform before sampling. Figure 5 As shown, when a data query instruction is received, the data in the database is indexed according to the query instruction, and phase demodulation is performed on the retrieved data, and the phase demodulation result is displayed.

[0096] Furthermore, if Figure 6 As shown, step S3 includes:

[0097] S31. When a query instruction for stored data is received, corresponding data in the database is retrieved according to the query instruction.

[0098] S32: converting the resolution of the retrieved corresponding data, and restoring the signal waveform before sampling through a second filter.

[0099] When the phase demodulation result, i.e., the sensor information, needs to be checked, the compressed data stored in the hard disk is read into the computer and then sent to a second filter. Preferably, the second filter is a bandpass filter, which has two functions: one is to filter out the noise still present in the signal, and the other is to restore the waveform of the compressed signal. The center frequency f of the second filter is C Satisfies: f` C =|f C -k*f s |, k is a positive integer; the bandwidth of the second filter is the half-maximum full width of the beat frequency signal bandwidth, which can be obtained by 0.8859 / T P The bandwidth of this bandpass filter can be set to the full width at half maximum of the beat frequency signal bandwidth, which can be estimated by . After passing through the second filter, the beat frequency signal waveform can be restored.

[0100] S4. Perform phase demodulation on the data after the resolution is converted and the signal waveform is restored to obtain sensing information in the form of a two-dimensional space-time matrix.

[0101] The sensor information can be obtained by following the conventional phase demodulation process. Note that the phase demodulation results are only used for display and will not be stored on the hard disk. If you need to view the demodulation results, you need to repeat the demodulation steps of reading data and filtering.

[0102] The above scheme is described in detail below with reference to specific embodiments:

[0103] In the first embodiment, it is assumed that the center frequency f of the beat signal in the Φ-OTDR optical system is c is 80MHz, pulse width T P The sampling rate is 100ns, the original sampling rate and sampling resolution are 250MSa / s and 16bit respectively, so the size of the original data collected by the system is 476.84MB / s.

[0104] like Figure 7 As shown in (b), the process of reducing the system data volume is explained by taking the data storage solution based on low sampling rate as an example:

[0105] 1. Send the beat frequency signal to a bandpass filter with a center frequency of 80 MHz and a bandwidth of 20 MHz.

[0106] 2. Calculate the sampling rate. According to the bandpass sampling theorem, the low sampling rate f S Can be a value from the following table:

[0107] Table 1 Applicable low sampling rate values

[0108] m <![CDATA[2·f U / m]]> <![CDATA[2·f U / m]]> 1 180MSa / s ∞ 2 90MSa / s 140MSa / s 3 60MSa / s 70MSa / s 4 45MSa / s 46.67MSa / s

[0109] Considering that when m = 4, the available sampling rate range is only 1.67MHz. If a sampling rate within this range is used, the signal may be aliased and introduce additional noise. When m = 3, the available sampling rate range is 60-70MSa / s, and values ​​within this range can be used for bandpass sampling. For the sake of discussion, we choose 62.5MSa / s as the low sampling rate f S value, which is exactly one quarter of the original sampling rate of 250MSa / s.

[0110] 3. Sample the data using a sampling rate of 62.5MSa / s and a sampling resolution of 16 bits.

[0111] 4. Store the collected raw data. Based on the sampling rate and sampling resolution in step 3, it can be calculated that the amount of data generated by the system per second is 119.21MB.

[0112] 5. Read in the stored raw data.

[0113] 6. Phase demodulation.

[0114] 7. Display the demodulated sensing information.

[0115] The above solution is based on low-sampling-rate data storage, utilizing only the bandpass sampling theorem to reduce the sampling rate during data acquisition. Because bandpass sampling is used, a bandpass filter is added before data acquisition to remove noise outside the signal's main lobe and prevent signal aliasing during sampling. Furthermore, this solution does not compress the waveform, eliminating the need for a filter to restore the waveform after data is read in. Compared to the original solution's data throughput of 476.84 MB / s, this solution's data throughput is 119.21 MB / s, representing a compression ratio of 4.

[0116] In the second specific embodiment, it is assumed that the scenario is the same as that in Example 1. The following shows the data processing flow based on the data compression storage solution with low sampling resolution:

[0117] 1. Sample the data using a sampling rate of 250MSa / s and a sampling resolution of 1 bit.

[0118] 2. Store the collected raw data. Based on the sampling rate and sampling resolution in step 1, it can be calculated that the amount of data generated by the system per second is 29.8MB / s

[0119] 3. Read the stored raw data

[0120] 4. Pad the input data to make it easier for the computer to process. Each sample point of the input data only occupies 1 bit, but the computer processes data in 8-bit bytes. Therefore, 7 zeros need to be added to the front of each sample point to facilitate computer processing.

[0121] 5. Send the padded data to a bandpass filter to restore the signal waveform. The center frequency of this bandpass filter is 80MHz, and the bandwidth can be set to 20MHz.

[0122] 6. Phase demodulation.

[0123] 7. Display the demodulated sensor information.

[0124] The above solution reduces the data volume by lowering the sampling resolution during data acquisition. Due to the 1-bit sampling resolution, the acquired beat frequency signal waveform becomes a square wave-like waveform. Therefore, before phase demodulation, a bandpass filter is required to extract the signal's main frequency component to restore the waveform. Compared to the original solution's data volume of 476.84 MB / s, this solution's data volume is 29.8 MB / s, with a compression ratio of 16.

[0125] In the specific embodiment 3, it is assumed that the scenario is consistent with that in Example 1. Figure 7 As shown in (c), the data processing flow of the data compression storage solution based on low sampling and sampling resolution is as follows:

[0126] 1. Send the beat frequency signal to a bandpass filter with a center frequency of 80 MHz and a bandwidth of 20 MHz.

[0127] 2. Calculate the sampling rate. This step uses the same sampling rate as in Example 1, which is 62.5MSa / s.

[0128] 3. Sample the data using a sampling rate of 62.5MSa / s and a sampling resolution of 1 bit.

[0129] 4. Store the collected raw data. Based on the sampling rate and sampling resolution in step 3, it can be calculated that the amount of data generated by the system per second is 7.45MB / s

[0130] 5. Read the stored raw data

[0131] 6. Fill in the digits of the read data to facilitate computer processing.

[0132] 7. Send the padded data to a bandpass filter to restore the signal waveform. The center frequency of this bandpass filter is 80MHz, and the bandwidth is set to 10MHz.

[0133] 8. Phase demodulation.

[0134] 9. Display the demodulated sensor information.

[0135] This scheme combines bandpass sampling theorem and low-bit sampling technology. Compared to the original scheme's data throughput of 476.84MB / s, this scheme's data throughput is 7.45MB / s, achieving a compression ratio of 64%.

[0136] On the other hand, the present invention also provides a high storage efficiency distributed optical fiber sensing system, which can significantly increase the storable monitoring time while also maintaining dense sampling points of phase demodulation results on the distance axis.

[0137] Furthermore, this system stores processed raw data rather than conventional phase demodulation results; when acquiring data, the data module of this system uses a low sampling rate and low resolution (unconventional 8 bits or higher) to sample the data; when storing data, the stored object is the signal extracted in groups after removing the invalid data at the end; two bandpass filters are used, the first one is used to achieve low sampling rate signal acquisition, and the second one is used to recover the waveform of the low-precision beat frequency signal.

[0138] like Figure 8 As shown, the sensor system includes: an optical sensor module 1 and a data processing module 2.

[0139] The optical sensing module 1 includes: a laser transmitter, a first fiber coupler 103 , an acousto-optic modulator 104 , a first optical amplifier, a first circulator 106 , a sensing optical cable 107 , a second optical amplifier, a second fiber coupler 111 and a balanced photodetector 112 .

[0140] The laser transmitter is used to transmit a continuous laser beam to the first fiber coupler 103. The first fiber coupler 103 is used to split the continuous laser beam into two identical light paths: one path is sent to an acousto-optic modulator (AOM), and the other path is sent to a second fiber coupler 111. The AOM is used to modulate the received continuous laser beam into pulsed light using a driving signal and transmit it to the first optical amplifier. The first optical amplifier is used to amplify the pulsed light and transmit it to the first circulator 106. The first circulator 106 transmits the amplified pulsed light to the sensor cable 107 and also receives the backscattered Rayleigh light returned from the sensor cable and transmits it to the second optical amplifier. The second optical amplifier is used to amplify the backscattered Rayleigh light and transmit it to the second circulator. The second circulator transmits the amplified backscattered Rayleigh light to the second fiber coupler 111. The second fiber coupler 111 is used to beat the backscattered Rayleigh light (which has been filtered out of noise) with the other path of the continuous laser beam and transmit the resulting optical beat signal to the balanced photodetector 112. The balanced photodetector 112 is used to convert the beat frequency signal in optical form into a beat frequency signal in electrical form and send the signal to the data processing module.

[0141] Furthermore, an optical isolator 102 for isolating the echo light is provided between the laser emitter and the first optical fiber coupler 103 .

[0142] Furthermore, the laser transmitter is a narrow linewidth laser; and the first optical amplifier and the second optical amplifier are both erbium-doped fiber amplifiers.

[0143] Furthermore, the system further includes: a fiber Bragg grating filter connected to the second port of the second circulator; the fiber Bragg grating filter is used to filter out the spontaneous emission noise of the amplified back Rayleigh scattered light, and send the filtered back Rayleigh scattered light with noise to the second fiber coupler 111.

[0144] Furthermore, the data processing module 2 includes: a first filter 201, a data acquisition card 202, a processor, a storage medium 203, a second filter 206, and an IQ phase demodulation module 204. The first filter 201 is used to extract the main lobe of the spectrum of the electrical beat frequency signal and filter out noise outside the main lobe of the spectrum. The data acquisition card 202 is used to sample the signal retaining only the main lobe of the spectrum at a low sampling rate and / or low resolution and store it in the storage medium. The processor is used to retrieve the corresponding data from the storage medium according to the received query instruction and convert the resolution of the corresponding data to the required resolution (i.e., to the resolution required for computer processing. The computer's requirement for the resolution (or number of bits) of the data is generally an integer multiple of 8). The second filter 206 is used to restore the data converted to the required resolution to the signal waveform before sampling. The IQ phase demodulation module 201 is used to perform IQ phase demodulation on the data after the resolution conversion and signal waveform restoration to obtain sensor information in the form of a two-dimensional space-time matrix. In addition, the data processing module 2 also includes: a display device 205 for displaying the demodulation results. Preferably, the processor is a computer that receives instructions and extracts stored data from a storage medium 203 such as a hard disk according to the instructions, first pads the data with a resolution (originally 1 to 7 bits, padded to 8 bits or 16 bits or higher), and then transmits it to the back for filtering and demodulation.

[0145] The high-storage-efficiency distributed optical fiber sensing system provided by the present invention is applicable to a phase-sensitive optical time-domain reflectometer based on heterodyne detection. The system can be divided into two parts: an optical sensing system and a data processing module.

[0146] The specific implementation process of the optical sensing system is as follows: the continuous laser output by the narrow-linewidth laser 101 passes through the optical isolator 102 and enters the fiber coupler 103 to be divided into two light paths. The first continuous light path is converted into pulsed light after being modulated by the drive signal of the acousto-optic modulator 104. The pulsed light is then sent to the first erbium-doped fiber amplifier 105 for signal amplification, and then enters the sensing optical cable 107 through the circulator 106. When the pulsed light is transmitted forward in the sensing optical cable 107, it also generates backscattered Rayleigh light. The entire backscattered Rayleigh light generated when a single pulsed light is transmitted to the end of the optical fiber is a set of sampling signals for the sensing optical cable 107. After passing through the circulator, the backscattered Rayleigh light returning from the sensing optical cable is first sent to the second erbium-doped fiber amplifier 108 for signal amplification. It then passes through the second circulator 109 and enters the fiber grating filter 110 to filter out the amplified spontaneous emission noise. It then beats with the second continuous light in the coupler 111. Finally, the beat frequency optical signal is sent to the balanced photodetector 112 to convert the optical signal into an electrical signal.

[0147] The data processing module implements the following process: The beat signal output by the balanced photodetector 112 is a one-dimensional signal composed of several groups of continuous sampling signals. To demodulate disturbances, the sampling signals must be extracted by group and spliced ​​into a two-dimensional signal for phase demodulation. To extend system monitoring time, the high-storage-efficiency distributed fiber optic sensing system provided by the present invention first feeds the one-dimensional signal output by the balanced photodetector 112 into a first filter 201 to remove excess out-of-band noise. The beat signal is then sampled at a low sampling rate and resolution by the data acquisition card 202. The signals collected by the data acquisition card are still several groups of continuous sampling signals of the sensor optical cable. They are extracted in groups, and then after removing the invalid data at the end of each group, they are stored in the storage medium 203 with high precision. When reading data later, these stored low-precision sampling signals after removing the invalid data at the end will first be up-converted in resolution, and then sent to a second filter 206 for restoring the beat frequency signal waveform, and then phase demodulated using the IQ phase demodulation method to obtain the sensing information, which is displayed in the demodulation result display module 205.

[0148] It is worth mentioning that the distributed sensing system referred to in the present invention is a system that can measure disturbances occurring at any position on the entire sensing optical fiber. Distributed sensing means that the entire optical fiber can be sensed, that is, countless point sensors are distributed on the entire optical fiber; while the point-type optical fiber sensing system can only measure a specified area on the optical fiber.

[0149] In addition, the present invention also provides a detection data storage and reading device for backscattered Rayleigh light of an optical fiber, comprising: at least one database; and a memory communicatively connected to the at least one database; wherein the memory stores instructions that can be executed by the at least one database, and the instructions are executed by the at least one database so that the at least one database can execute the detection data storage method and the detection data reading method for the phase-sensitive optical time-domain reflectometer as described above.

[0150] Since the systems / devices described in the above embodiments of the present invention are systems / devices used to implement the methods of the above embodiments of the present invention, those skilled in the art will be able to understand the specific structures and variations of these systems / devices based on the methods described in the above embodiments of the present invention, and thus will not be described in detail here. All systems / devices used in the methods of the above embodiments of the present invention are within the scope of protection of the present invention.

[0151] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0152] The present invention is described with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions.

[0153] It should be noted that, in the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In claims enumerating several means, several of these means may be embodied by one and the same hardware. The use of the words first, second, third etc. is for convenience only and does not indicate any order. These words may be understood as part of the component name.

[0154] In addition, it should be noted that, in the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0155] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments after learning the basic creative concept. Therefore, the claims should be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0156] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims and their equivalents, the present invention shall also include such modifications and variations.

Claims

1. A detection data storage method for a phase-sensitive optical time-domain reflectometer, characterized in that: include: Extracting the main lobe of the spectrum of the detection signal of the backscattered Rayleigh light generated by the optical fiber to be tested; The signal retaining only the main lobe of the spectrum is sampled at a low sampling rate and / or low resolution and stored in a preset database, including: At a low sampling rate f s The signal retaining only the main lobe of the spectrum is sampled, and the low sampling rate satisfies the following relationship: 2f U / m≤f S ≤2f L / (m-1), Where, f U is the high cutoff frequency of the beat signal, f U =f C +B / 2;f L is the low cutoff frequency of the beat signal, f L =f C -B / 2; m is an integer, 1≤m≤f U / B; and / or, The signal retaining only the main lobe of the spectrum is sampled with a low sampling resolution r, and the value range of r is 1 to 7 bits; After sampling the signal retaining only the main lobe of the spectrum at a low sampling rate and / or low resolution, removing invalid data at the end of each group of continuous signals retaining only the main lobe of the spectrum; According to the storage switch state of the preset database, the signal with only the main lobe of the spectrum removed and the invalid data at the end is stored in the preset database or called to a corresponding display device for display.

2. The detection data storage method for phase-sensitive optical time-domain reflectometry according to claim 1, characterized in that: Extracting the main lobe of the spectrum of the detection signal of the backscattered Rayleigh light generated by the optical fiber to be tested includes: Acquire the detection signal of the backscattered Rayleigh light generated by the optical fiber under test when the signal is transmitted; Extracting the main lobe of the spectrum of the detection signal through a first filter, and filtering out noise outside the main lobe of the spectrum; The detection signal is a beat frequency signal composed of several groups of continuous signals and is a one-dimensional signal. The center frequency of the first filter is f c The same as the center frequency of the beat signal, and the bandwidth B of the first filter and the pulse width T of the detection pulse P Satisfies: B = 2 / T p .

3. The detection data storage method for phase-sensitive optical time-domain reflectometry according to claim 1, wherein: According to the storage switch state of the preset database, the signal with only the main lobe of the spectrum removed from the end of the invalid data is stored in the preset database or called to a corresponding display device for display; When the storage switch of the database is turned on, the signal currently temporarily stored in the buffer zone with only the main lobe of the spectrum removed from the end of the signal is stored in the preset database; When the storage switch of the database is not turned on, determining whether the display switch of the display device is turned on; If the display switch is on, phase demodulation is performed on the signal temporarily stored in the buffer with only the main lobe of the spectrum removed from the end of the invalid data, and the phase demodulation result is displayed on the display device; The data not stored in the preset database all exists in the buffer zone.

4. A method for reading detection data for a phase-sensitive optical time-domain reflectometer, characterized in that: include: Retrieving the corresponding data stored in the database according to the method according to any one of claims 1 to 3 according to the received query instruction, converting the resolution of the corresponding data and restoring the signal waveform before sampling; Phase demodulation is performed on the data after the resolution is converted and the signal waveform is restored to obtain sensing information in the form of a two-dimensional space-time matrix.

5. The method for reading detection data for a phase-sensitive optical time-domain reflectometer according to claim 4, wherein: Retrieving corresponding data from a database according to a received query instruction, converting the resolution of the corresponding data, and restoring the signal waveform before sampling includes: Upon receiving a query instruction for stored data, retrieve the corresponding data in the database according to the query instruction; Converting the retrieved corresponding data into a different resolution, and restoring the signal waveform before sampling through a second filter; Wherein, the center frequency f' of the second filter C Satisfies: f` C =|f C -k*f s |, k is a positive integer, f s For low sampling rate.

6. A high storage efficiency distributed optical fiber sensing system, characterized in that: include: An optical sensor module and a data processing module for executing the method according to any one of claims 1 to 3 and the method according to claim 4 or 5; The optical sensing module includes: a laser transmitter, a first optical fiber coupler, an acousto-optic modulator, a first optical amplifier, a first circulator, a sensing optical cable, a second optical amplifier, a second optical fiber coupler and a balanced photodetector; The laser transmitter is used to send continuous laser light to the first optical fiber coupler; The first fiber coupler is used to split the continuous laser light into two identical light paths, one continuous laser light path is used to be sent to the acousto-optic modulator, and the other continuous laser light path is used to be sent to the second fiber coupler; The acousto-optic modulator is used to modulate the received continuous laser light into pulsed light through a driving signal, and send the pulsed light to the first optical amplifier; The first optical amplifier is used to amplify the pulse light and send it to the first circulator; The first circulator is used to send the amplified pulsed light to the sensing optical cable, and is also used to receive the backscattered Rayleigh light returned by the sensing optical cable and send it to the second optical amplifier; The second optical amplifier is used to amplify the Rayleigh backscattered light and send it to the second circulator; The second circulator sends the amplified Rayleigh backscattered light to a second fiber coupler; The second optical fiber coupler is used to beat the noise-filtered back Rayleigh scattered light with another continuous laser, and send the obtained beat signal in the form of light to the balanced photodetector; The balanced photodetector is used to convert the beat frequency signal in optical form into a beat frequency signal in electrical form and send the signal to the data processing module.

7. A high storage efficiency distributed optical fiber sensing system according to claim 6, characterized in that: An optical isolator for isolating echo light is further provided between the laser emitter and the first optical fiber coupler; the laser emitter is a narrow linewidth laser, and the first optical amplifier and the second optical amplifier are both erbium-doped fiber amplifiers.

8. A high storage efficiency distributed optical fiber sensing system according to claim 7, characterized in that: The system further includes: a fiber Bragg grating filter connected to the second port of the second circulator; The fiber Bragg grating filter is used to filter out the spontaneous emission noise of the amplified Rayleigh backscattered light, and send the filtered Rayleigh backscattered light with noise to the second fiber coupler.

9. A high storage efficiency distributed optical fiber sensing system according to any one of claims 6 to 8, characterized in that: The data processing module includes: a first filter, a data acquisition card, a processor, a storage medium, a second filter and an IQ phase demodulation module; The first filter is used to extract the main lobe of the spectrum of the electrical beat frequency signal and filter out noise outside the main lobe of the spectrum; The data acquisition card is used to sample the signal retaining only the main lobe of the spectrum at a low sampling rate and / or low resolution, and store the sample in the storage medium; The processor is used to retrieve corresponding data from the storage medium according to the received query instruction, and convert the resolution of the corresponding data to a required resolution; The second filter is used to restore the data converted to the required resolution to the signal waveform before sampling; The IQ phase demodulation module is used to perform IQ phase demodulation on the data after the resolution is converted and the signal waveform is restored, so as to obtain sensing information in the form of a two-dimensional space-time matrix.

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