A method for measuring and controlling the length of an optical fiber, a terminal and a storage medium

Abstract

The application discloses a kind of measurement control method of optical fiber length, terminal and storage medium, method includes: according to time-of-flight algorithm, double optical pulse is generated in the ring optical path of optical fiber structure;First measurement data when placing the optical fiber to be measured in the ring device and second measurement data when not placing the optical fiber to be measured are obtained, and the length of the optical fiber to be measured is calculated according to the first measurement data and the second measurement data;According to the length of the optical fiber to be measured obtained by multiple calculations, the sampling characteristics of the oscilloscope are combined, and the sampling data obtained by multiple sampling are statistically analyzed to obtain the accurate measurement result of the optical fiber to be measured.The application analyzes the sampling characteristics of the oscilloscope, processes data by probability statistics, and improves the accuracy of time-of-flight method for measuring optical fiber length under the limitation of oscilloscope sampling rate.

Description

Technical Field

[0001] This invention relates to the field of optical fiber technology, and in particular to a method for measuring and controlling the length of an optical fiber, a terminal, and a storage medium. Background Technology

[0002] Distributed fiber optic sensors have shown great promise in many fields, such as structural health monitoring of large buildings; leak and damage monitoring of oil and gas pipelines; temperature monitoring of power line hotspots; fire early warning monitoring in tunnels and factories; and intrusion monitoring of important facilities and sites. An effective fiber optic length measurement system can provide accurate calibration for distributed fiber optic sensors, improving their detection and positioning accuracy.

[0003] The main methods currently used include Time-of-Flight (TOF), Optical Time-Domain Reflectometer (OTDR), Optical Frequency-Domain Reflectometer (OFDR), asymmetric Sagnac interferometer, and laser mode-locking. The speed of light in optical fiber is approximately 2 × 10⁻⁶. 8 The current performance of oscilloscopes and photodetectors is insufficient to meet the requirements for precise measurement at speeds of m / s. OTDR utilizes the weak backscattered Rayleigh light generated when light propagates in optical fibers, essentially employing Time-of-Flight (TOF) detection. OTDR requires signal averaging to reduce detection noise and improve accuracy, but it also requires processing large amounts of data, resulting in long measurement times and detection blind zones; its measurement accuracy is generally on the order of meters. OFDR has very high equipment requirements, demanding light sources with low phase noise and a large linear sweep frequency range, leading to very high costs. Due to the limitation of the coherence length of the light source, the accuracy and measurement range of OFDR are mutually limited, making it unsuitable for long-distance testing. Frequency-shift asymmetric Sagnac interferometers are susceptible to fiber torsion and disturbances during detection, producing geometric and photoelastic effects that change the polarization state of the light wave, directly affecting the measurement results and making it impossible to guarantee accuracy in practical applications. Laser mode-locking methods are easily affected by external interference and cannot directly measure the length of short optical fibers. Furthermore, many optical devices are bulky, have high environmental requirements, and poor stability, making them unsuitable for on-site testing. Therefore, a high-precision, low-cost, and easily integrated portable detection device is needed.

[0004] Therefore, existing technologies still need improvement. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method, terminal and storage medium for measuring and controlling the length of optical fibers, in order to solve the technical problems of low detection accuracy and high cost of traditional optical fiber length measurement and control methods.

[0006] The technical solution adopted by this invention to solve the technical problem is as follows:

[0007] In a first aspect, the present invention provides a method for measuring and controlling the length of an optical fiber, comprising:

[0008] Based on the time-of-flight algorithm, two optical pulses are generated in the ring optical path of the optical fiber structure;

[0009] Acquire first measurement data when the optical fiber to be tested is placed in the ring device and second measurement data when the optical fiber to be tested is not placed in the ring device, and calculate the length of the optical fiber to be tested based on the first measurement data and the second measurement data;

[0010] Based on the length of the optical fiber under test obtained through multiple calculations, and combined with the sampling characteristics of the oscilloscope, a probabilistic statistical analysis was performed on the sampling data obtained from multiple samplings to obtain the accurate measurement result of the optical fiber under test.

[0011] In one implementation, generating dual optical pulses in the ring optical path of the fiber optic structure according to the time-of-flight algorithm includes:

[0012] Control a single-mode laser to generate continuous laser light of a preset wavelength;

[0013] By controlling the input voltage of the acousto-optic modulator, a single pulse laser is generated.

[0014] The single pulse laser is input into the fiber coupler, and the optical signal output from the ring structure of the fiber coupler is obtained by the photodetector, and the optical signal is converted into an electrical signal.

[0015] The electrical signal is displayed on an oscilloscope.

[0016] In one implementation, the step of inputting a single optical pulse into the fiber coupler, acquiring the optical signal output from the ring structure of the fiber coupler through a photodetector, and converting the optical signal into an electrical signal includes, prior to:

[0017] The amplitude of the overall pulse is adjusted by the first adjustable fiber optic attenuator.

[0018] In one implementation, the step of inputting a single optical pulse into the fiber coupler, acquiring the optical signal output from the ring structure of the fiber coupler through a photodetector, and converting the optical signal into an electrical signal includes:

[0019] The single optical pulse is input into the fiber optic coupler;

[0020] The amplitude of the second pulse is adjusted by a second adjustable fiber optic attenuator;

[0021] The photodetector acquires the optical signal output from the ring structure of the fiber optic coupler and converts the optical signal into an electrical signal.

[0022] In one implementation, the step of performing probabilistic statistical analysis on the sampling data obtained from multiple samplings, based on the length of the optical fiber under test obtained through multiple calculations and in conjunction with the sampling characteristics of the oscilloscope, includes:

[0023] The first pulse received by the oscilloscope is located, and the rising edge position and threshold point of the first pulse are set.

[0024] Based on the rising edge position and threshold point of the first pulse, calculate the random values ​​that appear within the pulse peak range under multiple measurements;

[0025] The second pulse received by the oscilloscope is located, and the rising edge position and threshold point of the second pulse are set.

[0026] Calculate the time difference between the first pulse and the second pulse received by the oscilloscope;

[0027] The average length of the optical fiber under test is calculated multiple times based on the time difference and the random value, and the final length of the optical fiber under test is derived.

[0028] In one implementation, locating the first pulse point received by the oscilloscope and setting the rising edge position and threshold point of the first pulse includes:

[0029] The first threshold voltage is used as the positioning point of the first pulse, and the position of the first threshold voltage at the rising edge of the first pulse is set as t(0);

[0030] Set the position of the first oscilloscope sampling point after point t(0) as the threshold point t0.

[0031] In one implementation, locating the second pulse received by the oscilloscope and setting the rising edge position and threshold point of the second pulse includes:

[0032] The second threshold voltage is used as the positioning point of the second pulse, and the position of the second threshold voltage at the rising edge of the second pulse is set as t(1);

[0033] Set the position of the first oscilloscope sampling point after point t(1) as the threshold point t1.

[0034] In one implementation, the step of calculating the average length of the optical fiber under test multiple times based on the time difference and the random value, and deriving the final length of the optical fiber under test, includes:

[0035] Based on the time difference and the random value, it is calculated that there are exactly two types of flight time data that differ by a sampling interval t. S The probability of;

[0036] Calculate the expected value of the time difference T between the two pulses sampled by the oscilloscope based on the probability.

[0037] Based on the expected value and the average length of the optical fiber under test obtained from multiple calculations, the final length of the optical fiber under test is derived.

[0038] In a second aspect, the present invention also provides a terminal, comprising: a processor and a memory, the memory storing a fiber length measurement control program, which, when executed by the processor, is used to implement the fiber length measurement control method as described in the first aspect.

[0039] Thirdly, the present invention also provides a medium, which is a computer-readable storage medium storing a fiber length measurement control program, which, when executed by a processor, is used to implement the fiber length measurement control method as described in the first aspect.

[0040] The present invention, by employing the above technical solution, has the following effects:

[0041] This invention proposes a method to obtain fiber length data by generating dual pulses using an optical fiber coupler and by using the time-of-flight difference between the two pulses. This avoids problems related to pulse characteristic differences and circuit synchronization, thus reducing measurement errors. Furthermore, it analyzes the relationship between the pulse amplitude and the measured pulse interval when using an oscilloscope, and uses an adjustable optical fiber attenuator to adjust the amplitude of the second pulse during measurement, thereby improving measurement accuracy. By processing the data using probabilistic statistics, the accuracy of measuring fiber length using the time-of-flight method is improved under the limitation of the oscilloscope sampling rate. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0043] Figure 1 This is a flowchart of a fiber optic length measurement and control method in one implementation of the present invention.

[0044] Figure 2 This is a schematic diagram of a fiber optic length measurement and control system in one implementation of the present invention.

[0045] Figure 3 This is a schematic diagram of a fiber optic coupler generating a pulse cycle in one implementation of the present invention.

[0046] Figure 4 This is a schematic diagram of the discrete sampling signal of the oscilloscope in one implementation of the present invention.

[0047] Figure 5 This is a schematic diagram illustrating the effect of pulse amplitude on pulse interval in one implementation of the present invention.

[0048] Figure 6 This is a schematic diagram of the measurement results of an optical fiber with a nominal length of 20km in one implementation of the present invention.

[0049] Figure 7 This is a schematic diagram comparing the measurement control method with the test results of the OTDR device in one implementation of the present invention.

[0050] Figure 8 This is a functional schematic diagram of the terminal in one implementation of the present invention.

[0051] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0053] Exemplary methods

[0054] The main methods currently used include Time-of-Flight (TOF), Optical Time-Domain Reflectometer (OTDR), Optical Frequency-Domain Reflectometer (OFDR), asymmetric Sagnac interferometer, and laser mode-locking. The speed of light in optical fiber is approximately 2 × 10⁻⁶. 8The current performance of oscilloscopes and photodetectors is insufficient to meet the requirements for precise measurement at speeds of m / s. OTDR utilizes the weak backscattered Rayleigh light generated when light propagates in optical fibers, essentially employing Time-of-Flight (TOF) detection. OTDR requires signal averaging to reduce detection noise and improve accuracy, but it also requires processing large amounts of data, resulting in long measurement times and detection blind zones; its measurement accuracy is generally on the order of meters. OFDR has very high equipment requirements, demanding light sources with low phase noise and a large linear sweep frequency range, leading to very high costs. Due to the limitation of the coherence length of the light source, the accuracy and measurement range of OFDR are mutually limited, making it unsuitable for long-distance testing. Frequency-shift asymmetric Sagnac interferometers are susceptible to fiber torsion and disturbances during detection, producing geometric and photoelastic effects that change the polarization state of the light wave, directly affecting the measurement results and making it impossible to guarantee accuracy in practical applications. Laser mode-locking methods are easily affected by external interference and cannot directly measure the length of short optical fibers. Furthermore, many optical devices are bulky, have high environmental requirements, and poor stability, making them unsuitable for on-site testing. Therefore, a high-precision, low-cost, and easily integrated portable detection device is needed.

[0055] To address the aforementioned technical problems, this invention provides a method for measuring and controlling the length of optical fibers. This invention proposes using a fiber coupler to generate dual pulses and the time-of-flight difference of the two pulses to obtain fiber length data, thus avoiding problems related to pulse characteristic differences and circuit synchronization, and reducing measurement errors. Furthermore, it analyzes the relationship between the pulse amplitude and the measured pulse interval when using an oscilloscope, and uses an adjustable fiber attenuator to adjust the amplitude of the second pulse during measurement, improving measurement accuracy. Finally, it processes the data using probabilistic statistics, improving the accuracy of the time-of-flight method for measuring fiber length under the limitation of the oscilloscope sampling rate.

[0056] like Figure 1 As shown, this embodiment of the invention provides a method for measuring and controlling the length of an optical fiber, comprising the following steps:

[0057] Step S100: Based on the time-of-flight algorithm, generate dual optical pulses in the ring optical path of the optical fiber structure.

[0058] In this embodiment, the fiber length measurement and control method is applied in a terminal, which includes, but is not limited to, devices such as computers and mobile terminals.

[0059] In this embodiment, the fiber length measurement and control method is implemented through a fiber length measurement and control system. In this embodiment, a novel fiber length measurement system is proposed.

[0060] Fiber length and effective refractive index are prerequisites for distributed fiber optic sensing. This embodiment proposes a novel fiber optic length measurement system based on the time-of-flight method. In terms of measurement accuracy, measurement range, anti-interference capability, and equipment cost, most existing fiber optic length measurement technologies struggle to simultaneously meet these requirements. While time-of-flight-based measurement methods typically have lower accuracy, they offer greater system stability.

[0061] This invention, based on the time-of-flight method, utilizes a ring optical path in an optical fiber structure to generate dual optical pulses. The optical pulses obtained in this way exhibit consistent pulse characteristics while avoiding errors in circuit synchronization. The difference in flight time between the two sets of measurements—with and without the fiber under test placed in the ring device—is obtained. A simple calculation then yields the length of the fiber under test. Finally, after multiple measurements, and by combining the sampling characteristics of an oscilloscope, probabilistic statistical analysis is performed on the data obtained from the multiple samplings to obtain a precise result. This measurement method has strong anti-interference capabilities, and by combining probabilistic statistical methods, it can overcome the limitations of oscilloscope sampling speed, achieving higher precision measurements. This invention offers high precision, low cost, and measurement stability.

[0062] like Figure 2 As shown, the fiber length measurement and control system includes: a laser, an acousto-optic modulator, a first adjustable fiber attenuator, a fiber coupler, a photodetector, an oscilloscope, and a computer (i.e., a terminal) connected in sequence; wherein, the fiber coupler contains the fiber under test, the Y end of the fiber under test is connected to the second adjustable fiber attenuator, the second adjustable fiber attenuator is connected to the C interface in the fiber coupler, the X end of the fiber under test is connected to the delay fiber, and the delay fiber is connected to the D interface in the fiber coupler.

[0063] Specifically, in one implementation of this embodiment, step S100 includes the following steps:

[0064] Step S101: Control the single-mode laser to generate continuous laser light of a preset wavelength;

[0065] Step S102: Control the input voltage of the acousto-optic modulator to generate a single pulse laser;

[0066] Step S103: Input the single pulse laser into the fiber coupler, and obtain the optical signal output from the ring structure of the fiber coupler through a photodetector, and convert the optical signal into an electrical signal;

[0067] Step S104: Display the electrical signal using an oscilloscope.

[0068] In this embodiment, the system structure is as follows: Figure 2As shown, firstly, a continuous laser beam is generated using a single-mode laser with a center wavelength of 1550nm, i.e., a continuous 1550nm (preset wavelength) laser beam is produced. Then, by controlling the input voltage of the acousto-optic modulator (AOM), a switching effect is created on the optical path, generating a single pulse laser beam. This is then transmitted through a 2x2 fiber coupler.

[0069] like Figure 3 As shown, after a single light pulse passes through a 2x2 coupler, one portion of the light exits the ring structure, is converted into an electrical signal by a photodetector, and is received and displayed by an oscilloscope. The other portion remains in the ring device and continues to circulate. Therefore, when a pulse of light is input, multiple pulses of light can be obtained through circulation, and the time interval between each pulse is the time the light travels in the ring device.

[0070] In one implementation of this embodiment, the following steps are included before step S103:

[0071] Step S103a: Adjust the amplitude of the overall pulse by using the first adjustable fiber optic attenuator.

[0072] In one implementation of this embodiment, step S103 includes the following steps:

[0073] Step S1031: Input the single optical pulse into the fiber optic coupler;

[0074] Step S1032: Adjust the amplitude of the second pulse using the second adjustable fiber optic attenuator;

[0075] Step S1033: The optical signal output from the ring structure of the optical fiber coupler is acquired by the photodetector and converted into an electrical signal.

[0076] like Figure 2 As shown, in this embodiment, only the first two optical pulse signals are used in the system design. Two adjustable fiber optic attenuators (VOAs) are set up. The adjustable fiber optic attenuator connected after the acousto-optic modulator (i.e., the first adjustable fiber optic attenuator) mainly functions to adjust the amplitude of the overall pulse, while the adjustable fiber optic attenuator connected in the ring device (i.e., the second adjustable fiber optic attenuator) mainly functions to adjust the amplitude of the second output pulse.

[0077] Furthermore, the primary function of the time-delay fiber (TDF) in the ring apparatus is to prevent pulses from overlapping during the loop. First, the interval between the two pulses obtained after the pulsed light passes through the ring apparatus is measured. Then, the fiber under test (FUT) is placed into the ring apparatus, and the pulse interval is measured again. Based on these multiple measurements, an algorithm is applied to calculate the final result.

[0078] like Figure 1 As shown, in one implementation of this invention, the fiber length measurement and control method further includes the following steps:

[0079] Step S200: Obtain first measurement data when the optical fiber to be tested is placed in the ring device and second measurement data when the optical fiber to be tested is not placed. Calculate the length of the optical fiber to be tested based on the first measurement data and the second measurement data.

[0080] In this embodiment, the working mechanism of the fiber optic length measurement system is as follows:

[0081] like Figure 2 As shown, when the fiber under test is placed in the system, the optical path L1 of the first pulse can be represented as:

[0082] L1:→B→C→D→E

[0083] The optical path L2 of the second pulse can be represented as:

[0084] L2:→B→C→D→X→Y→C→D→E

[0085] Where X→Y is the length L of the optical fiber to be tested. FUT From the above two equations, the optical path difference ΔL between the first and second pulses can be obtained. FUT It can be represented as:

[0086] ΔL FUT (L2-L1):D→X→Y→C→D

[0087] The time difference Δt between the first and second pulses is obtained by collecting and processing signals from the oscilloscope. FUT It can be represented as:

[0088]

[0089] In the formula, c is the speed of light, and n eff Let be the effective refractive index of the optical fiber. Similarly, when the optical fiber under test is not placed, the optical path difference ΔL0 and the time difference Δt0 between the first and second pulses can be expressed as follows:

[0090] ΔL0:D→C→D

[0091]

[0092] Therefore, by subtracting the two sets of data obtained with and without the fiber under test in the fiber coupler loop, the flight time Δt of the light circulating in the fiber under test can be obtained:

[0093]

[0094] Therefore, the length L of the optical fiber under test FUT It can be derived from the above formula:

[0095]

[0096] The measurement accuracy of the above measurement methods is mainly limited by the sampling rate of the oscilloscope. In this embodiment, we improve upon this limitation as follows.

[0097] like Figure 1 As shown, in one implementation of this invention, the fiber length measurement and control method further includes the following steps:

[0098] Step S300: Based on the length of the optical fiber under test obtained through multiple calculations, and combined with the sampling characteristics of the oscilloscope, perform probabilistic statistical analysis on the sampling data obtained from multiple samplings to obtain the accurate measurement result of the optical fiber under test.

[0099] In this embodiment, because the oscilloscope samples the continuous electrical signal in reality in a discrete sampling manner, there is an error between the actual detected time-domain signal and the ideal signal. Based on this, this embodiment combines the sampling characteristics of the oscilloscope to perform probabilistic statistical analysis on the sampling data obtained from multiple samplings to obtain accurate measurement results of the optical fiber under test.

[0100] Specifically, in one implementation of this embodiment, step S300 includes the following steps:

[0101] Step S301: Locate the first pulse received by the oscilloscope and set the rising edge position and threshold point of the first pulse.

[0102] In one implementation of this embodiment, step S301 includes the following steps:

[0103] Step S3011: Use the first threshold voltage as the positioning point of the first pulse, and set the position of the first threshold voltage at the rising edge of the first pulse as t(0);

[0104] Step S3012: Set the position of the first oscilloscope sampling point after point t(0) as the threshold point t0.

[0105] like Figure 4 As shown, Figure 4The discrete sampling signal of the oscilloscope is an ideal pulse signal, with the peak voltage of both pulses being 1V. The oscilloscope is set to use a threshold voltage of 0.5V (i.e., the first threshold voltage) as the positioning point of the first pulse, and the position of 0.5V at the rising edge of the first pulse (i.e., the position of the first threshold voltage) is set to t(0) = 0. At the same time, the position of the first sampling point of the oscilloscope after point t(0) is set to t0, which is the threshold point.

[0106] Specifically, in one implementation of this embodiment, step S300 further includes the following steps:

[0107] Step S302: Based on the rising edge position and threshold point of the first pulse, calculate the random values ​​that appear within the pulse peak range under multiple measurements;

[0108] Step S303: Locate the second pulse received by the oscilloscope and set the rising edge position and threshold point of the second pulse.

[0109] like Figure 4 As shown, at the same sampling time on the oscilloscope, if the signal in the figure lags slightly (less than one sampling interval t)... S When the signal arrives earlier (less than a sampling interval t), the voltage corresponding to t0 is closer to 0.5V, meaning t0 is closer to 0; conversely, if the signal arrives earlier (less than a sampling interval t), the voltage will be closer to 0.5V. S As t0 approaches, the voltage corresponding to t0 deviates further from 0.5V, meaning the closer t0 is to t... S Therefore, with multiple measurements, the value of t0 will be within the sampling interval t. S The amplitude fluctuates within a certain range, depending on the arrival time of the signal and the start time of sampling by the oscilloscope. It exhibits a random phenomenon in multiple measurements, namely:

[0110] t0-t(0)=t0=t S ·rand

[0111] Where rand represents a random number in the range [0,1).

[0112] By calculating this random value and combining it with the sampling characteristics of the oscilloscope, a probabilistic statistical analysis is performed on the sampling data obtained from multiple samplings to obtain accurate measurement results for the optical fiber under test.

[0113] In one implementation of this embodiment, step S303 includes the following steps:

[0114] Step S3031: Use the second threshold voltage as the positioning point of the second pulse, and set the position of the second threshold voltage at the rising edge of the second pulse as t(1);

[0115] Step S3032: Set the position of the first oscilloscope sampling point after point t(1) as the threshold point t1.

[0116] In this embodiment, the 0.5V position of the rising edge of the second pulse is set as t(1) in the same manner as the first pulse point. Obviously, theoretically, the time difference between t(0) and t(1) is equal to the single flight time of the laser in the ring device:

[0117]

[0118] Where L is the total length of the optical fiber in the ring device, c is the speed of light, and n eff Let be the effective refractive index of the optical fiber. Similarly, let t1 be the position of the first oscilloscope sampling point after point t(1). Then the value of t1 can be derived as:

[0119]

[0120] By setting the sampling point position t0 of the first pulse point on the oscilloscope and the sampling point position t1 of the second pulse point on the oscilloscope, the time difference T between the two pulses can be calculated.

[0121] Specifically, in one implementation of this embodiment, step S300 further includes the following steps:

[0122] Step S304: Calculate the time difference between the first pulse and the second pulse received by the oscilloscope;

[0123] Step S305: Calculate the average length of the optical fiber under test multiple times based on the time difference and the random value, and deduce the final length of the optical fiber under test.

[0124] In this embodiment, the flight time corresponding to the fiber length in the ring device can be represented by the time difference T between the two pulses sampled by the oscilloscope:

[0125]

[0126] make:

[0127]

[0128] You can get

[0129] T = [ab]·t S

[0130] When multiple measurements are taken using the same fiber optic cable and the same oscilloscope sampling rate, 'a' is a fixed constant value, while 'b' is a random number within the range [0,1) that varies with each measurement. Therefore, the change in 'b' during multiple measurements will directly affect the result of the rounding function.

[0131] In one implementation of this embodiment, step S305 includes the following steps:

[0132] Step S3051: Based on the time difference and the random value, calculate that there are exactly two types of flight time data that differ by one sampling interval t. S The probability of;

[0133] Step S3052: Calculate the expected value of the time difference T between the two pulses sampled by the oscilloscope based on the probability.

[0134] Step S3053: Based on the expected value and the average length of the optical fiber under test obtained from multiple calculations, the final length of the optical fiber under test is derived.

[0135] In this embodiment, the formula for the time difference between the two pulses sampled by the oscilloscope is T = [ab]·t. S ,set up:

[0136] a = a int +a dec

[0137] Among them, a int a is the integer part of a. dec This represents the decimal part of a. In multiple measurements, the result of T will show a... int ·t S With (a) int +1)·t S These two values ​​are as follows Figure 5 As shown, by performing multiple measurements on a single optical fiber, the calculated time-of-flight data contains exactly two data points that differ by a sampling interval t. S The data. Theoretically, the probabilities of these two values ​​are calculated as follows:

[0138]

[0139]

[0140] Therefore, based on probability, the expected value of T can be calculated:

[0141] E(T) = P([ab] = a int )·a int ·t S +P([ab]=a int +1)·(a int +1)·t S

[0142] =(1-a dec )·a int ·t S +adec ·(a int +1)·t S =(a int +a dec )·t S =a·t S

[0143] Therefore, according to the law of large numbers, when T is repeatedly measured, its arithmetic mean almost certainly converges to the expected value E(T). Finally, by using its average value to calculate the value of a, the fiber length L can be deduced.

[0144] like Figure 6 As shown, tests were conducted on an optical fiber with a nominal length of 20km. A total of 50,000 measurements were performed, and only 9.8304 × 10⁻⁶ results were obtained. -5 and 9.83424×10 -5 Both scenarios are consistent with the results discussed above. The probability of their occurrence and the average time were calculated, ultimately yielding a result of 19625.067m.

[0145] In addition, four sets of optical fibers of different lengths, ranging from 100m to 50km, were tested and compared with OTDR devices on the market, such as... Figure 7 As shown. The measurement accuracy of the OTDR device is ±(1m + 3 × L × 10). -5 In this embodiment, the system uses only an oscilloscope with a sampling rate of 26.041667 MS / s to test the optical fiber. The test results are basically similar to those of OTDR measurements. Furthermore, when measuring long distances, OTDR devices are unstable, with multiple measurements showing fluctuations of tens of meters. However, when using the system of this embodiment for multiple measurements, the measurement results only fluctuate at the centimeter level, demonstrating strong stability.

[0146] In this embodiment, in two measurements—one with the fiber under test and one without—the amplitude of the pulse obtained with the fiber under test will always be smaller than the amplitude obtained without the fiber due to the inherent loss in the single-mode fiber. If the pulse amplitude changes, not only will the amplitude change on the oscilloscope, but the interval between the two pulses will also be affected. In this embodiment, the system structure remains unchanged, and the amplitude of the second pulse is controlled only by the second adjustable fiber attenuator in the ring device. Figure 5 As shown, a total of four sets of pulse intervals with different pulse amplitudes were measured, with 32 measurements for each set. It can be seen that as the pulse amplitude increases, even if the fiber length remains constant, the pulse interval will increase, affecting the final measurement results. Therefore, it is necessary to adjust the amplitude of the second pulse using a second adjustable fiber attenuator before each measurement to ensure that the amplitude of the second pulse remains at a constant level.

[0147] This embodiment achieves the following technical effects through the above technical solution:

[0148] This embodiment proposes a method to obtain fiber length data by generating dual pulses using an optical fiber coupler and by using the time-of-flight difference of the two pulses. This avoids problems related to pulse characteristic differences and circuit synchronization, thus reducing measurement errors. Furthermore, it analyzes the relationship between the pulse amplitude and the measured pulse interval when using an oscilloscope, and uses an adjustable optical fiber attenuator to adjust the amplitude of the second pulse during measurement, thereby improving measurement accuracy. By processing the data using a probabilistic statistical method, the accuracy of measuring fiber length using the time-of-flight method is improved under the limitation of the oscilloscope sampling rate.

[0149] Exemplary device

[0150] Based on the above embodiments, the present invention also provides a terminal, comprising: a processor, a memory, an interface, a display screen, and a communication module connected via a system bus; wherein, the processor is used to provide computing and control capabilities; the memory includes a storage medium and internal memory; the storage medium stores an operating system and computer programs; the internal memory provides an environment for the operation of the operating system and computer programs in the storage medium; the interface is used to connect to external devices, such as mobile terminals and computers; the display screen is used to display corresponding information; and the communication module is used to communicate with a cloud server or a mobile terminal.

[0151] When the computer program is executed by the processor, it is used to implement the operation of a method for measuring and controlling the length of an optical fiber.

[0152] It will be understood by those skilled in the art that Figure 8 The schematic diagram shown is merely a partial structural diagram related to the present invention and does not constitute a limitation on the terminal to which the present invention is applied. A specific terminal may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0153] In one embodiment, a terminal is provided, comprising: a processor and a memory, the memory storing a fiber length measurement control program, which, when executed by the processor, is used to implement the fiber length measurement control method as described above.

[0154] In one embodiment, a storage medium is provided, wherein the storage medium stores a fiber length measurement control program, which, when executed by the processor, is used to implement the operation of the fiber length measurement control method as described above.

[0155] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include non-volatile and / or volatile memory.

[0156] In summary, this invention provides a method, terminal, and storage medium for measuring and controlling the length of an optical fiber. The method includes: generating dual optical pulses in a ring optical path of an optical fiber structure according to a time-of-flight algorithm; acquiring first measurement data when the optical fiber under test is placed in the ring device and second measurement data when the optical fiber under test is not placed; calculating the length of the optical fiber under test based on the first and second measurement data; and performing probabilistic statistical analysis on the sampled data obtained from multiple calculations of the length of the optical fiber under test, combined with the sampling characteristics of an oscilloscope, to obtain an accurate measurement result of the optical fiber under test. This invention improves the accuracy of measuring the length of an optical fiber using the time-of-flight method by analyzing the sampling characteristics of an oscilloscope and processing the data through probabilistic statistics, under the limitation of the oscilloscope's sampling rate.

[0157] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for measuring and controlling the length of an optical fiber, characterized in that, include: Based on the time-of-flight algorithm, two optical pulses are generated in the ring optical path of the optical fiber structure; Acquire first measurement data when the optical fiber to be tested is placed in the ring device and second measurement data when the optical fiber to be tested is not placed in the ring device, and calculate the length of the optical fiber to be tested based on the first measurement data and the second measurement data; Based on the length of the optical fiber under test obtained through multiple calculations, and combined with the sampling characteristics of the oscilloscope, a probabilistic statistical analysis is performed on the sampling data obtained from multiple samplings to obtain an accurate measurement result of the optical fiber under test, including: locating the first pulse received by the oscilloscope, and setting the rising edge position and threshold point of the first pulse; Based on the rising edge position and threshold point of the first pulse, calculate the random value appearing within the pulse peak range under multiple measurements; locate the second pulse received by the oscilloscope, and set the rising edge position and threshold point of the second pulse; calculate the time difference between the first pulse and the second pulse received by the oscilloscope; calculate the average length of the fiber under test multiple times based on the time difference and the random value, and derive the final length of the fiber under test.

2. The method for measuring and controlling the length of optical fiber according to claim 1, characterized in that, The process of generating dual optical pulses in a ring optical path of an optical fiber structure according to a time-of-flight algorithm includes: Control a single-mode laser to generate continuous laser light of a preset wavelength; By controlling the input voltage of the acousto-optic modulator, a single pulse laser is generated. The single pulse laser is input into the fiber coupler, and the optical signal output from the ring structure of the fiber coupler is obtained by the photodetector, and the optical signal is converted into an electrical signal. The electrical signal is displayed using an oscilloscope.

3. The method for measuring and controlling the length of optical fiber according to claim 2, characterized in that, The process of inputting a single optical pulse into the fiber optic coupler, acquiring the optical signal output from the ring structure of the fiber optic coupler through a photodetector, and converting the optical signal into an electrical signal includes, prior to: The amplitude of the overall pulse is adjusted by the first adjustable fiber optic attenuator.

4. The method for measuring and controlling the length of optical fiber according to claim 2, characterized in that, The process of inputting a single optical pulse into an optical fiber coupler, acquiring the optical signal output from the ring structure of the optical fiber coupler through a photodetector, and converting the optical signal into an electrical signal includes: The single optical pulse is input into the fiber optic coupler; The amplitude of the second pulse is adjusted by a second adjustable fiber optic attenuator; The photodetector acquires the optical signal output from the ring structure of the fiber optic coupler and converts the optical signal into an electrical signal.

5. The method for measuring and controlling the length of optical fiber according to claim 1, characterized in that, The step of locating the first pulse point received by the oscilloscope and setting the rising edge position and threshold point of the first pulse includes: The first threshold voltage is used as the positioning point of the first pulse, and the position of the first threshold voltage at the rising edge of the first pulse is set as follows: ; Will The location of the first oscilloscope sampling point after the threshold point is set as the threshold point. .

6. The method for measuring and controlling the length of an optical fiber according to claim 1, characterized in that, The step of locating the second pulse received by the oscilloscope and setting the rising edge position and threshold point of the second pulse includes: The second threshold voltage is used as the positioning point of the second pulse, and the position of the second threshold voltage at the rising edge of the second pulse is set as follows: ; Will The location of the first oscilloscope sampling point after the threshold point is set as the threshold point. .

7. The method for measuring and controlling the length of an optical fiber according to claim 1, characterized in that, The step of calculating the average length of the optical fiber under test multiple times based on the time difference and the random value, and deriving the final length of the optical fiber under test, includes: Based on the time difference and the random value, it is calculated that there are exactly two types of flight time data that differ from each other by one sampling interval. The probability of; The time difference between the two pulses sampled by the oscilloscope is calculated based on the probability. Expected value; Based on the expected value and the average length of the optical fiber under test obtained from multiple calculations, the final length of the optical fiber under test is derived.

8. A terminal, characterized in that, include: The processor and memory, the memory storing a fiber length measurement control program, which, when executed by the processor, is used to implement the fiber length measurement control method as described in any one of claims 1-7.

9. A medium, characterized in that, The medium is a computer-readable storage medium that stores a fiber length measurement control program. When executed by a processor, the fiber length measurement control program is used to implement the operation of the fiber length measurement control method as described in any one of claims 1-7.

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