WO2021082522A1

WO2021082522A1 - Optical fiber testing method based on optical time-domain reflectometer, and optical time-domain reflectometer

Info

Publication number: WO2021082522A1
Application number: PCT/CN2020/100863
Authority: WO
Inventors: 李明; 陈飞; 吴春阳; 龙运; 苏玉锋
Original assignee: 华为技术有限公司
Priority date: 2019-11-01
Filing date: 2020-07-08
Publication date: 2021-05-06
Also published as: CN112769471A; CN112769471B

Abstract

The present application provides an optical fiber testing method based on an optical time-domain reflectometer, and an optical time-domain reflectometer, said method comprising: an optical time-domain reflectometer emitting a plurality of pulsed lasers within a preset testing time, the test range corresponding to each of the pulsed lasers being greater than or equal to the preset testing length in the optical fiber to be tested which is connected to the optical time-domain reflectometer, the test range corresponding to each pulsed laser being different; using each pulsed laser to generate corresponding sub-test data; calculating the average value of the sub-test data to obtain a test result. Hence, if the test range is less than the length of the optical fiber to be tested, then the plurality of pulsed lasers having different test ranges are used to test an optical fiber having a preset test length, and it is possible to effectively eliminate the effects of ghosting, making the test results more accurate.

Description

Method for testing optical fiber based on optical time domain reflectometer and optical time domain reflectometer

This application requires the priority of the Chinese patent application submitted to the Chinese Patent Office on November 1, 2019, with the application number 201911059393.2, and the invention titled "A method for optical fiber testing based on an optical time domain reflectometer and an optical time domain reflectometer". Rights, the entire contents of which are incorporated in this application by reference

.

Technical field

This application relates to the technical field of optical fiber testing, and in particular to a method of optical fiber testing based on an optical time domain reflectometer and an optical time domain reflectometer.

Background technique

Optical fiber communication is a communication method that uses light waves as the carrier and optical fiber as the transmission medium. The optical fiber contains a large number of fusion splices, jumpers and single boards. During use, these locations are more prone to transmission loss and damage. At the same time, most of the optical fibers are made of glass, which is relatively fragile. Therefore, during use, it is more It is prone to breakage and incorrect bending. The above-mentioned situations can be called events, and these events will affect the communication quality of the optical fiber. Generally, an Optical Time Domain Reflectometer (OTDR) is used to determine the location of an event in the optical fiber to improve the test accuracy of the OTDR, which can effectively improve the OTDR's positioning accuracy of the event in the optical fiber.

Generally, the fiber can be divided into two parts according to the installation position of the fiber in the application. One part is the intra-station connection fiber between the combiner/demultiplexer and the optical distribution frame (Optical Distribution Frame, ODF), that is, the near-end fiber; The transmission fiber between the ODF and the transmission receiving end, that is, the remote fiber. Correspondingly, events that occur in the near-end optical fiber can be referred to as near-end events, and events that occur in the far-end optical fiber can be referred to as far-end events. For the near-end fiber, because the near-end fiber usually has more fiber jumpers and single boards, and the length of the near-end fiber is small, the distance between the adjacent end events in the near-end fiber is small, in order to be able to accurately test these short distances. Event, it is necessary to improve the resolution of the OTDR to adjacent events. For the remote fiber, because the length of the remote fiber is long, if the entire remote fiber needs to be tested, the test distance of the OTDR needs to exceed the total length of the fiber to be tested, that is, the OTDR has a larger test dynamic range. However, it is difficult for an OTDR to have both high resolution for near-end events and large test dynamic range for far-end optical fibers.

Summary of the invention

This application provides a method for optical fiber testing based on an optical time domain reflectometer and an optical time domain reflectometer. At the same time, it provides a higher near-end event resolution and a larger test dynamic range, so as to improve the optical time domain reflectometer test The accuracy of the event.

In the first aspect, this application provides a method for optical fiber testing based on an optical time domain reflectometer, including:

The optical time domain reflectometer emits multiple pulsed lasers within a preset test time, wherein the pulse width of each pulsed laser is equal, and the test range corresponding to each pulsed laser is greater than or equal to that of the light. For the preset test length in the optical fiber to be tested connected to the time domain reflectometer, each of the pulsed lasers corresponds to a different test range, and the test range is the distance traveled by the optical signal within the pulse interval time of the pulsed laser;

Generating sub-test data, where the sub-test data refers to test data obtained by using each of the pulsed lasers to perform a test in a corresponding sub-test time within the preset test time;

Calculate the average value of the sub-test data to obtain the test result.

When the optical time domain reflectometer is testing events in the optical fiber, if the set test range is less than the length of the fiber to be tested, ghost images will appear in the test results of the optical time domain reflectometer, that is, the optical time domain reflectometer will The abnormally enhanced reflected light signal is received, which affects the judgment of whether the event exists and the true location of the event. The present invention tests the fiber under test by emitting multiple sets of pulsed lasers corresponding to different test ranges to make ghosts appear in different positions, and then obtains the average value of the test data corresponding to each set of pulsed lasers to determine the ghosts The test data corresponding to the reflected signal that is actually generated due to the event, so as to achieve the effect of eliminating ghosts and accurately determining the event.

In an implementation manner, the pulse width of the pulsed laser is less than the time required for the optical signal to propagate between two adjacent proximal events in the proximal optical fiber in the optical fiber to be tested.

The optical time domain reflectometer judges the location of the event according to the reflected signal generated by the pulsed laser in the optical fiber, the pulse width corresponds to the duration of each pulse in the pulsed laser, and correspondingly, the duration of the reflected signal generated by the pulsed laser encountering the event It is proportional to the pulse width. Reducing the pulse width can reduce the duration of the reflected signal correspondingly. When the pulse width is less than the time required for the optical signal to propagate between two adjacent events, it can prevent a single pulse of the pulsed laser from encountering two adjacent events. The reflected signals generated during the event cover each other, so that the reflected signal corresponding to each event can be clearly distinguished, so that the optical time domain reflectometer can accurately determine the event. Since the distance between adjacent events is usually smaller than the distance between adjacent far-end events, ensuring that the pulse width is less than the time required for the optical signal to propagate between two adjacent near-end events can ensure that the pulse width is less than the optical signal The required events are propagated between two adjacent far-end events to ensure the resolution of near-end events and far-end events.

In an implementation manner, the transmission distance of each of the pulsed lasers in the corresponding sub-test time is greater than or equal to the preset test length.

According to the test principle of the optical time domain reflectometer, only the fiber that the pulsed laser passes through can be measured. Therefore, in order to ensure that the fiber to be tested with the preset test length can be measured, it is necessary to ensure that each pulsed laser is within the corresponding sub-test time The transmission distance is greater than or equal to the preset test length. Since the distance that the pulsed laser can travel is limited by time and laser energy, and the laser energy is affected by the pulse width, therefore, to ensure the distance that the pulsed laser can travel, that is, the pulsed laser is required to have a large enough pulse width to Support the pulsed laser to propagate the preset test length.

In an implementation manner, the calculating the average value of all sub-test data, and after obtaining the test result, includes:

According to the test result, a test curve reflecting the test data corresponding to different lengths of the optical fiber to be tested is generated.

The test results can contain multiple representations such as numerical values, tables, curves, etc. According to the test results, corresponding test curves can be generated. The curves can be used to more intuitively display the corresponding reflected signals of the pulsed laser at various positions of the fiber to be tested, so as to quickly determine the event. .

In the second aspect, this application provides a method for optical fiber testing based on an optical time domain reflectometer, including:

The optical time domain reflectometer emits one or more first pulse lasers with a first pulse width during the first test time, and emits a second pulse laser with a second pulse width during the second test time, wherein each The transmission distance of one of the first pulse lasers in the first test time is greater than or equal to the length of the proximal fiber in the fiber to be tested connected to the optical time domain reflectometer, and the first pulse width is less than The time required for the optical signal to propagate between two adjacent proximal events in the near-end optical fiber, and the transmission distance of the second pulsed laser within the second test time is greater than or equal to that of the optical fiber to be tested length;

Generate first test data and second test data, where the first test data refers to test data obtained by using the first pulsed laser to perform a test within the first test time, and the second test data is Refers to the test data obtained by using the second pulsed laser to perform a test within the second test time;

Generate a near-end event test result and a far-end event test result, where the near-end event test data refers to test data corresponding to the near-end optical fiber in the first test data, and the far-end event test result is Refers to the test data corresponding to the remote optical fiber in the optical fiber to be tested in the second test data.

The fiber to be tested can be divided into two parts: the near-end fiber and the far-end fiber. Due to the differences in the distribution of events in the two parts and the corresponding fiber length, it is difficult to test the two parts with the same pulse width pulse laser. The need for testing. The combined pulse laser method is adopted, and the first pulse laser is used for the near-end fiber to meet the needs of the near-end fiber for effectively distinguishing near-end events and increase the accuracy of testing near-end events; at the same time, the first pulsed laser is used for the far-end fiber. Two-pulse laser to meet the requirement of covering the entire fiber under test for the test distance of the remote fiber to test the complete remote fiber. And extract the useful data in the first test data and the second test data as the final test result, making the test result more pertinent.

In an implementation manner, when the optical time domain reflectometer emits a first pulsed laser within the first test time, the first pulsed laser corresponds to a first test range, and the first test range is an optical signal The distance traveled within the pulse interval of the first pulse laser, and the first test range is greater than or equal to the length of the optical fiber to be tested.

Ensure that the first test range corresponding to the first pulse laser is greater than or equal to the length of the fiber to be tested, which can effectively avoid ghost images when the optical time domain reflectometer is testing the near-end fiber, thereby ensuring the accuracy of the near-end fiber test.

In an implementation manner, when the optical time domain reflectometer emits a plurality of first pulse lasers within the first test time, each of the first pulse lasers corresponds to a second test range, and the second test range Is the distance that the optical signal travels within the pulse interval of the first pulsed laser, where each of the second test ranges is different, and each of the second test ranges is greater than or equal to the length of the proximal optical fiber , And less than the length of the optical fiber to be tested;

The test range reflects the sampling length of the optical time domain reflectometer for the fiber to be tested, that is, the set test length. The smaller the test range, the shorter the time it takes for the optical signal to cover the test range in an ideal state. Shortening the test range to cover the proximal fiber can effectively shorten the test time of the first pulse laser on the proximal fiber, thereby saving the overall test time. In order to avoid the ghosting problem caused by the test range being less than the length of the fiber to be tested, the use of multiple measurements can effectively eliminate ghosts and improve the accuracy of the test.

In an implementation manner, the difference between the second test ranges corresponding to the two first pulse lasers is at least greater than the distance between two adjacent proximal events.

The length of the test range will affect the location of the ghost. When the test range is extended, the location of the ghost will move the corresponding length in the opposite direction of the pulsed laser propagation, and the location of the ghost can easily be confused with the event. In order to make the ghost images generated by the two second test ranges mismatch each other, so as to meet the condition of averaging to eliminate the ghost images, the difference between the two second test ranges needs to be greater than the distance between the two near-end events .

In an implementation manner, the first pulse width is 100 ns to 800 ns, and the second pulse width is 10000 ns to 20000 ns.

In an implementation manner, the generating the first test data includes:

Using each of the first pulse lasers to test in the corresponding sub-test time in the first test time to obtain sub-test data respectively;

The average value of all the sub-test data is calculated to obtain the first test data.

The position of the ghost image produced by the first pulse laser of different test ranges in the corresponding sub-test time is different. However, a new set of test data can be obtained by putting multiple sets of sub-test data together to calculate the average value. That is, the first test data, this group of test data can eliminate abnormally increased data, and at the same time present a normal data change trend. Through this data change trend, the event can be accurately determined.

In an implementation manner, the generating the first test data and the second test data includes:

According to the first test data, a first test curve reflecting the test data corresponding to the different lengths of the optical fiber to be tested is generated; according to the second test data, a first test curve reflecting the test data corresponding to the different lengths of the optical fiber to be tested is generated 2. Test curve.

In an implementation manner, the generating the near-end event test result and the far-end event test result includes:

The near-end event test result is generated according to the test curve corresponding to the near-end optical fiber in the first test curve, and the far-end event test result is generated according to the test curve corresponding to the far-end optical fiber in the second test curve.

If the second test range is greater than the length of the near-end optical fiber, the first test curve contains part of the far-end optical fiber test curve, and the second test curve will also include the near-end optical fiber test curve, and both parts of the data are Data that needs to be discarded. Therefore, it is necessary to cut out part of the test curve corresponding to the near-end fiber from the first test curve as the near-end event test result, and cut out the part of the test curve corresponding to the far-end fiber from the second test curve as the test result of the near-end event. Remote event test results to ensure the accuracy of test results.

In an implementation manner, the near-end event test result is generated according to the test curve corresponding to the near-end optical fiber in the first test curve, and the test result of the near-end event is generated according to the test curve corresponding to the far-end optical fiber in the second test curve. The remote event test results generated by the test curve include:

Generating a difference curve between the first test curve and the second test curve;

Dividing the difference curve into a plurality of calculation units with a preset length;

Calculate the root mean square of all values in the calculation unit;

Determining a splicing position, where the splicing position is a data node corresponding to the smallest root mean square on the difference curve;

Determine the target node of the optical fiber to be tested according to the length of the optical fiber to be tested corresponding to the splicing position;

Generate a near-end event test result and a far-end event test result, where the near-end event test result refers to the portion corresponding to the target node from the beginning of the fiber to be tested in the first test curve, and the remote The end event test result refers to the part corresponding to the end of the optical fiber to be tested from the target node in the second test curve.

Through the above method, the points on the first test curve and the second test curve corresponding to the split point between the proximal fiber and the distal fiber can be accurately determined, so that the obtained test result is more accurate.

The present application provides an optical time domain reflectometer, including: a laser transmitter, a signal receiver, and a processor; the laser transmitter is used to emit pulsed laser light according to the method of optical fiber testing based on the optical time domain reflectometer, and the signal The receiver is used to receive the optical signal reflected by the optical fiber to be tested, and the processor is used to process the optical signal received by the signal receiver into test data.

This application provides a computer program product containing instructions, wherein when the computer program product runs on an optical time domain reflectometer, the optical time domain reflectometer is caused to perform fiber testing based on the optical time domain reflectometer Methods.

Description of the drawings

In order to explain the technical solutions of the present application more clearly, the following will briefly introduce the drawings needed in the embodiments. Obviously, for those of ordinary skill in the art, without paying creative labor, Other drawings can also be obtained from these drawings.

FIG. 1 is a schematic diagram of an optical fiber application scenario provided by an embodiment of the application;

2 is a flowchart of a method for optical fiber testing provided by an embodiment of the application;

Figure 3 is a schematic diagram of the location where ghost images are generated;

FIG. 4 is a flowchart of a method for optical fiber testing provided by an embodiment of the application;

Figure 5(a) is a first test curve corresponding to the first pulsed laser provided by this embodiment of the application;

Figure 5(b) is a second test curve corresponding to the second pulsed laser provided by this embodiment of the application;

Figure 5(c) is a test curve obtained after splicing provided by the embodiment of this application;

FIG. 6 is a schematic structural diagram of an optical time domain reflectometer provided by an embodiment of the application.

Illustration description:

Among them, 1-controller, 2-laser transmitter, 3-signal receiver, 4-processor.

Detailed ways

The following describes the technical solutions in the embodiments of the present invention clearly and completely with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

Hereinafter, the terms “first”, “second”, etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present embodiment, unless otherwise specified, "plurality" means two or more.

The optical fiber is divided from the physical structure of the setting, and the optical fiber can be divided into two parts, namely the proximal fiber and the distal fiber. As shown in Figure 1, it is a schematic diagram of an optical fiber application scenario, in which the multiplexer and demultiplexer unit and the ODF are used as the site structure, and the fiber used to connect each optical device in the site is used as the near-end fiber; the ODF and ODF The transmission and receiving ends are used as the structure outside the site, and the optical fiber used for signal transmission outside the site is used as the remote optical fiber. Specifically, the site usually contains optical components such as multiplexer/demultiplexer unit, wavelength division multiplexer unit, optical fiber connector, flange, and optical attenuator connected to the transmitting end. The optical fiber connected between these optical devices is the near-end optical fiber. ; The fiber that is pulled out of the site is the remote fiber.

The connection between the optical device and the near-end optical fiber, the fusion splice of the optical fiber itself, the breakage and bending of the optical fiber itself, etc., will all affect the quality of signal transmission. These conditions can be called events. Usually, the types of events can include attenuation, There are four types of gain, reflection and tail end. Only by accurately identifying these events can the quality of the fiber be repaired and improved. The OTDR is usually connected to the combiner/demultiplexer, by emitting pulsed laser light to the optical fiber, and receiving the optical signal reflected by the pulsed laser light propagating in the optical fiber, to determine the presence or absence of an event and the location of the event.

Generally, the OTDR will set the range to be tested during the test, that is, the test range. The test range can be equal to the length of the fiber to be tested or less than the length of the fiber to be tested. Generally, the test range of OTDR is achieved by controlling the test time of each pulse in the pulsed laser. The test time of each pulse is the pulse from the OTDR transmitter to the end of the test range, and then from the end of the test range to the OTDR transmitter. The time required. The emission time interval between two adjacent pulses in a pulsed laser is the test time of each pulse. However, it should be noted that when the test range adopted by the OTDR is less than the length of the fiber to be tested, ghost images will appear in the test data. Specifically, after a pulse in the pulsed laser reaches the test range, the OTDR will continue to emit the next pulse. At this time, since the previous pulse can continue to propagate in the fiber to be tested, if the previous pulse still maintains a higher energy , Then when the pulse encounters an event again, it will return a strong reflected signal. When this reflected signal is on the way back to the OTDR, it will inevitably encounter the next pulse. At this time, the two signals will be fed back to the OTDR after being superimposed. , Let the OTDR determine that the place is an event based on the superimposed signal. However, it may not be a real event here, and the error of the test data caused by the above-mentioned reasons is a ghost. It can be seen that if the test range is equal to or greater than the length of the fiber to be tested, ghost images can be effectively avoided, thereby ensuring the accuracy of the test data. But when the test range is less than the length of the fiber to be tested, it is necessary to further eliminate ghost images to ensure the accuracy of the test data.

Example 1

This application provides a method for optical fiber testing based on an optical time domain reflectometer. As shown in FIG. 2, it is a flowchart of a method for optical fiber testing provided by an embodiment of this application, and the method includes:

S1. The optical time domain reflectometer emits multiple pulsed lasers within a preset test time, wherein the pulse width of each pulsed laser is equal, and the test range corresponding to each pulsed laser is greater than or equal to that of all pulsed lasers. For the preset test length in the optical fiber to be tested connected to the optical time domain reflectometer, the test range corresponding to each of the pulsed lasers is different, and the test range is the distance that the optical signal travels within the pulse interval time of the pulsed laser ；

S2. Generating sub-test data, where the sub-test data refers to test data respectively obtained by using each of the pulsed lasers to perform a test in a corresponding sub-test time in the preset test time;

S3. Calculate the average value of the sub-test data to obtain a test result.

When the test range is less than the length of the fiber to be tested, multiple pulse lasers are used for testing to achieve the effect of eliminating ghost images. Among them, the test range corresponding to each pulse laser is set to be different. However, it should be noted that the test range corresponding to each pulse laser needs to be equal to or greater than the preset test length, because only when the test range is equal to or greater than the preset test length can the pulse laser cover the set Test the length to test the optical fiber of the preset test length.

Before the OTDR emits the pulsed laser, it will first set a total test time, which is composed of the sub-test time corresponding to each pulsed laser. Usually the test time is obtained by estimation. For example, if the test range corresponding to each pulse laser is known, the test time required for each pulse in the pulse laser can be estimated by d=(c×t)/2. According to the preset number of pulses, the sub-test time required by each pulsed laser can be estimated, and then the total test time can be estimated based on the total sub-test time. Generally, the total test time can be appropriately set to be greater than the estimated total test time to ensure the completion of each pulse laser test.

Each pulse laser will complete multiple pulse tests for the fiber with the preset test length in the corresponding sub-test time. At this time, the feedback signal of each pulse during the test will form a group at the OTDR For the test data, in order to avoid the instability problem during pulse emission and the influence of external factors on the test process, the average value of the test data obtained from each pulse can be taken as the sub-test data of the pulse laser.

Since the test range of each pulse laser is less than the length of the fiber to be tested, ghost images will be generated in the test data. From the principle of ghost generation described above, it can be seen that the location of ghost images is inversely proportional to the test range. That is, if the test range is extended, the location of the ghost image will move to the opposite direction of the pulse laser propagation. As shown in Figure 3, it is a schematic diagram of the location of the ghost image. You can see the pulse laser A, B, C, D, and at the same time Test the optical fiber OS under test, where the preset test length is OX, the test range of pulsed laser A is OP1, the test range of pulsed laser B is OP2, the test range of pulsed laser C is OP3, and the test range of pulsed laser D is OP4 , There is OX＜OP1＜OP2＜OP3＜OP4＜OS. If they are all at the same event Q, the signals reflected by the four pulse lasers at event Q are superimposed on the next pulse at a, b, c, d, namely The ghost position of pulse laser A is at a, the ghost position of pulse laser B is at b, the ghost position of pulse laser C is at c, and the ghost position of pulse laser D is at d.

It can be seen that the test data for a single pulsed laser will inevitably be affected by ghosts. However, after the test data corresponding to all the pulsed lasers are put together for average calculation, the value of a certain pulsed laser at the ghost can be calculated After averaging with the test data of other pulse lasers at the place, an average value is obtained. In this way, after averaging the values of each ghost image, a new set of test data can be obtained, which is similar to the new test data. Compared with the original test data corresponding to each pulse laser, there is a new trend of change. For example, the value of pulse laser A at a is an abnormally increasing trend, but for the new trend, the new test data is at a Compared with the data at other locations, the increasing trend of the value is already lower than the abnormal range, that is, the value of the new test data at a is a normal increasing trend, and a can no longer be used as a ghost position, and then Play the effect of successfully eliminating the ghost at a. In the same way, ghost images in other places can be eliminated. For the new test data, if the trend of the corresponding value change at a certain ghost image does not increase abnormally, then that place is the real event. Among them, all or part of the sub-test data can be used for averaging calculation to eliminate ghost images.

From the above description, it is necessary to stagger the positions of the ghost images generated by each pulse laser to eliminate the ghost images by averaging. Therefore, it is necessary to use pulsed lasers corresponding to different test ranges for testing.

At the same time, the pulse width is the time required to form a single pulse. Correspondingly, the feedback signal generated when the pulse encounters an event will continue for the same time as the pulse width. It can be seen that different pulse widths will cause the ghost image formed. The corresponding length range is different. When the ghost image is eliminated by the above average value, if the pulse width of each pulse laser is different, it will be difficult to accurately determine the location of the original ghost image that needs attention from the average value. At the same time, according to the commonly used control variable method in calculations, as few variables as possible are guaranteed, which can simplify the comparison process, and at the same time, make the calculated results more accurate.

When the test range is less than the length of the fiber to be tested according to the embodiment of the application, the fiber of the preset test length can be tested by multiple pulsed lasers with different test ranges, which can effectively eliminate the influence of ghosts and make the test results more accurate .

Example 2

On the basis of Embodiment 1, the pulse width of the pulsed laser is less than the time required for the optical signal to propagate between two adjacent proximal events in the proximal fiber in the optical fiber to be tested.

OTDR judges the location of the event based on the reflected signal generated by the pulsed laser in the optical fiber. The pulse width corresponds to the duration of each pulse in the pulsed laser. Accordingly, the duration of the reflected signal generated by the pulsed laser encountering the event is proportional to the pulse width. Proportional relationship. Reducing the pulse width can reduce the duration of the reflected signal correspondingly. When the pulse width is less than the time required for the optical signal to propagate between two adjacent events, it can prevent a single pulse of the pulsed laser from encountering two adjacent events. The reflected signals generated during the event cover each other, so that the reflected signal corresponding to each event can be clearly distinguished, so that the optical time domain reflectometer can accurately determine the event. Since the distance between adjacent events is usually smaller than the distance between adjacent far-end events, ensuring that the pulse width is less than the time required for the optical signal to propagate between two adjacent near-end events can ensure that the pulse width is less than the optical signal The required events are propagated between two adjacent far-end events to ensure the resolution of near-end events and far-end events.

In one implementation, the pulse width used is calculated according to formula (1),

Pulse_width=(res×2×n)/c (1)

Among them, Pulse_width represents the pulse width used, res represents the distance between two adjacent near-end events, n represents the refractive index of the fiber under test, and c is the propagation speed of the optical signal in the fiber under test.

Example 3

Based on Embodiments 1 and 2, the transmission distance of each pulsed laser within the corresponding sub-test time is greater than or equal to the preset test length.

According to the OTDR test principle, only the fiber through which the pulsed laser passes can be tested. Therefore, in order to ensure that the fiber under test with a preset test length can be tested, it is necessary to ensure that the transmission distance of each pulsed laser during the corresponding sub-test time is greater than Or equal to the preset test length. Because the distance that the pulsed laser can travel is limited by time and laser energy, at the same time, the laser energy is affected by the pulse width. Because the test time of each pulse in the pulsed laser is fixed, that is, it corresponds to the test range. Therefore, on the basis of a certain test range, to ensure the distance that the pulsed laser can travel, it is mainly required that the pulsed laser has a large enough pulse width to support the pulsed laser to propagate the preset test length, which means that the pulsed laser has sufficient dynamic range. .

It can be seen that the test method provided in this embodiment can not only enable the pulsed laser to have a higher event resolution, but also enable the pulsed laser to test all fibers with a predetermined test length to ensure the integrity of the test.

Example 4

On the basis of the above embodiment, the calculation of the average value of all the sub-test data, and after the test result is obtained, includes: according to the test result, generating a test curve reflecting the test data corresponding to the different lengths of the optical fiber to be tested.

Generally, test results can include multiple representations such as numerical values, tables, and curves. Although numerical values, tables, and other representations can accurately reflect the test results of various locations on the optical fiber, the tester needs to further analyze these tests, such as Compare the abnormally increased value, etc., to determine the location of the event. This embodiment generates a corresponding test curve according to the test result, and the curve can be used to more intuitively display the corresponding reflected signal of the pulsed laser at each position of the fiber to be tested, which is convenient for quickly determining the location of the event, and provides testers with a more convenient and easy-to-understand Test Results.

In actual test work, it is often necessary to test the entire fiber to be tested. From the above, the fiber to be tested can be divided into two parts, namely the near-end fiber and the far-end fiber. Therefore, the distance between the proximal events in the proximal fiber is relatively close. It can be seen from Embodiment 2 that for accurately distinguishing adjacent proximal events, the pulse width of the pulsed laser needs to be strictly limited. For the remote fiber, due to the long distance between the connecting devices in the remote fiber, the pulse width generally used will not be greater than this distance. Therefore, the problem of low resolution of the remote event usually does not occur, but , The length of the remote fiber is large, which requires that the pulsed laser must have enough energy to spread to cover the entire length of the fiber to be tested. Therefore, for the measurement of the remote fiber, the pulse width of the pulsed laser needs to be increased as much as possible. It can be seen that when testing two parts of optical fiber, the pulse laser used has completely different requirements. Therefore, it is difficult to achieve the best test results by using only the same pulse laser to test two parts of optical fiber at the same time.

Example 5

In view of the above-mentioned problems, the present application provides a method for optical fiber testing based on optical time domain reflectometer. As shown in FIG. 4, it is a flowchart of a method for optical fiber testing, and the method includes:

S101. The optical time domain reflectometer emits one or more first pulse lasers with a first pulse width during the first test time, and emits a second pulse laser with a second pulse width during the second test time, wherein , The transmission distance of each of the first pulse lasers in the first test time is greater than or equal to the length of the proximal fiber in the fiber to be tested connected to the optical time domain reflectometer, and the first pulse The width is less than the time required for the optical signal to propagate between two adjacent near-end events in the near-end optical fiber, and the transmission distance of the second pulsed laser in the second test time is greater than or equal to the under-test The length of the optical fiber;

S102. Generate first test data and second test data, where the first test data refers to test data obtained by using the first pulsed laser to perform a test within the first test time, and the second test Data refers to test data obtained by performing a test using the second pulsed laser within the second test time;

S103. Generate a near-end event test result and a far-end event test result, where the near-end event test data refers to test data corresponding to the near-end optical fiber in the first test data, and the remote event test The result refers to the test data corresponding to the remote optical fiber in the optical fiber to be tested in the second test data.

In this embodiment, a combined pulsed laser is adopted, and different pulsed lasers are used for testing for different optical fibers, so as to meet the requirements of different optical fibers for testing.

Specifically, the OTDR emits a first pulse laser for the proximal fiber. The first pulse laser has a first pulse width. In order to ensure the resolution of the proximal event, the first pulse width is required to be smaller than the optical signal between two adjacent proximal events. The time required for propagation between. The first pulse width can be determined according to formula (1). For details, refer to Embodiment 2, which will not be repeated here. At the same time, it should be noted that if the first pulse width is too small, the first pulse laser will have lower energy, and it cannot be guaranteed that the first pulse laser can cover all the proximal fibers. In order to ensure the integrity of the proximal fiber testing , It is also necessary to ensure that the first pulse width must be sufficient to support the transmission distance of the first pulse laser in the first test time to be greater than or equal to the length of the proximal fiber, that is, to reach a certain dynamic range. The OTDR emits a second pulse laser to the remote fiber. The second pulse laser has a second pulse width. In order to ensure the test integrity of the remote event, the second pulse width must be sufficient to support the second pulse laser within the second test time. The transmission distance is greater than or equal to the length of the fiber under test, that is, a certain dynamic range is reached.

Wherein, the first test time corresponds to the total test time of all the first pulsed lasers, and the second test time corresponds to the total test time of the second pulsed lasers. The first test time can be estimated based on the time required for the first pulse laser to propagate in the set test range and the number of pulses in the first pulse laser to complete the test. Similarly, the second test time can be estimated based on the time required for the second pulse laser to propagate in the set test range and the number of pulses in the second pulse laser to complete the test.

Among them, the test can be performed in the order of emitting all the first pulsed lasers first and then the second pulsed lasers; it can also be tested in the order of emitting the second pulsed lasers first and then all the first pulsed lasers; or it can be performed in the order of the first pulses The test is performed in the order of alternate emission of the laser and the second pulsed laser; it is also possible to first label each of the first pulsed laser and the second pulsed laser, and then sequence according to a preset number, and emit the corresponding pulsed laser for testing.

The corresponding first test data can be obtained by using the first pulsed laser to test in the first test time, and the corresponding second test data can be obtained by using the second pulsed laser to test in the second test time. Generally, in order to ensure the integrity of the near-end fiber and the far-end fiber test, the test range corresponding to the first pulse laser is set to be greater than the length of the near-end fiber, and the test range corresponding to the second pulse laser is set to be greater than the length to be tested. The length of the fiber. Therefore, the first test data will include part of the test data that does not belong to the near-end optical fiber, and the second test data will include part of the test data that does not belong to the far-end optical fiber. In order to ensure the accuracy of the test results, it is necessary to extract the test data corresponding to the near-end optical fiber from the first test data as the near-end event test result, and extract the test data corresponding to the far-end optical fiber from the second test data as the remote event Test Results.

It can be seen that the method for testing the optical fiber provided in this embodiment can test the near-end events and the far-end events in a targeted manner, so that the test results are more accurate.

Example 6

On the basis of Example 5, when the optical time domain reflectometer emits a first pulsed laser within the first test time, the first pulsed laser corresponds to the first test range, and the first test range is light. The distance that the signal propagates within the pulse interval time of the first pulse laser, and the first test range is greater than or equal to the length of the optical fiber to be tested.

It can be seen from the foregoing that when the test range is greater than or equal to the length of the fiber to be tested, the test data will not have the problem of ghosting. At this time, only one first pulse laser needs to be emitted to obtain more accurate test data.

At the same time, due to the test requirements for the remote fiber, the test range corresponding to the second pulse laser must be greater than or equal to the length of the fiber to be tested, so that the theoretical basis for testing a complete remote fiber can be provided. Therefore, there is no ghosting problem in the test process of the remote fiber, and no special limitation is made on the test range corresponding to the second pulse laser in this application.

Example 7

On the basis of Embodiment 5, when the optical time domain reflectometer emits multiple first pulse lasers within the first test time, each of the first pulse lasers corresponds to the second test range, and the second test The range is the distance that the optical signal travels within the pulse interval time of the first pulsed laser, wherein each of the second test ranges is different, and each of the second test ranges is greater than or equal to that of the proximal fiber The length is less than the length of the optical fiber to be tested.

The test range reflects the sampling length of the optical time domain reflectometer for the fiber to be tested, that is, the set test length. The smaller the test range, the shorter the time it takes for the optical signal to cover the test range in an ideal state. Since the first pulse laser is used to test the near-end optical fiber, if the test range is set to be greater than or the length of the fiber to be tested, it is equivalent to the first pulse laser that needs to spend more test time in the far-end optical fiber, which will cause very large Time wasted. In order to avoid wasting time, the first pulse laser can be set to correspond to the second test range, and the second test range is only required to be greater than or the length of the proximal fiber.

It can be seen from the above that if the test range is less than the length of the fiber to be tested, ghosting problems will appear in the test data. At this time, you can launch multiple pulse lasers with different test ranges, and then set the corresponding The test data is averaged to eliminate ghosting. In this embodiment, multiple first pulse lasers are emitted, and each first pulse laser corresponds to the second test range.

Further, each of the first pulse lasers is used to test in the corresponding sub-test time in the first test time to obtain sub-test data respectively; the average value of all the sub-test data is calculated to obtain the first test data.

The position of the ghost image produced by the first pulse laser of different test ranges in the corresponding sub-test time is different. However, a new set of test data can be obtained by putting multiple sets of sub-test data together to calculate the average value. That is, the first test data, this group of test data can eliminate abnormally increased data, and at the same time present a normal data change trend. Through this data change trend, the event can be accurately determined. For specific explanation, please refer to Embodiment 1, which will not be repeated here.

It can be seen from the above that the elimination of ghost images is related to the number of first pulse lasers. Theoretically, the number of first pulse lasers has an ability to eliminate ghost images of 5*logN, where N represents the number of first pulse lasers. When the number of one pulse laser is 5 to 10, the ghost image can be eliminated effectively.

The first pulse laser can be emitted according to the corresponding second test range from small to large, or according to the corresponding second test range from large to small, or according to a custom order.

In the method for testing the near-end optical fiber provided in this embodiment, although multiple first pulse lasers are used for testing, it takes multiple sets of sub-testing time, but because the far-end optical fiber is much larger than the total length of the multiple second test ranges Therefore, the first test time used when the first pulse laser corresponds to the second test range in this embodiment is much shorter than the first test time used when the first pulse laser corresponds to the first test range. It can be seen that this application not only can effectively eliminate the influence of ghost images, but also can effectively improve the test efficiency.

Example 8

On the basis of Example 7, the difference between the second test ranges corresponding to the two first pulse lasers is at least greater than the distance between two adjacent proximal events.

The length of the test range will affect the location of the ghost. When the test range is extended, the location of the ghost will move the corresponding length in the opposite direction of the pulsed laser propagation, and the location of the ghost can easily be confused with the event. In order to make the ghost images generated by the two second test ranges mismatch each other, so as to meet the condition of averaging to eliminate the ghost images, the difference between the two second test ranges needs to be greater than the distance between the two near-end events . It can be known through experiments that the minimum value of the difference between the two second test ranges can be preferably set to 10 times the distance between the near-end events, so that the effect of eliminating ghost images is more significant.

Based on the above embodiment, the first pulse width may be selected to be 100ns˜800ns, and the second pulse width may be 10,000ns˜20,000 ns.

The above two parameter ranges, after many experiments, the selection range of the first pulse width and the second pulse width can be obtained, which can effectively meet the requirements of the general near-end optical fiber for the resolution and dynamic range of the near-end event, and can also effectively meet the general far-end The fiber's requirements for dynamic range can be directly used by testers, thereby reducing the time it takes for testers to consult the comparison table and calculation when setting parameters, thereby improving test efficiency.

Example 9

Based on the foregoing embodiment, the generating of the first test data and the second test data includes: generating, according to the first test data, a first test curve reflecting test data corresponding to different lengths of the optical fiber to be tested; and according to the first test data; The second test data is to generate a second test curve reflecting the test data corresponding to the different lengths of the optical fiber to be tested.

The test results can contain multiple representations such as numerical values, tables, curves, etc. According to the test results, corresponding test curves can be generated. The curves can be used to more intuitively display the corresponding reflected signals of the pulsed laser at various positions of the fiber to be tested, so as to quickly determine the event. . For details, please refer to Embodiment 4, which will not be repeated here.

Example 10

Based on the above embodiment, the generating the near-end event test result and the far-end event test result includes: generating the near-end event test result according to the test curve corresponding to the near-end optical fiber in the first test curve, and according to the first test curve The second test curve corresponding to the remote optical fiber in the test curve generates a remote event test result.

Example 11

On the basis of Embodiments 9 and 10, this embodiment provides a method for further generating test results. The test result of the near-end event is generated according to the test curve corresponding to the near-end optical fiber in the first test curve. Generating a remote event test result from a test curve corresponding to the remote fiber in the second test curve includes: generating a differential curve between the first test curve and the second test curve; The difference curve is divided into multiple calculation units; the root mean square of all the values in the calculation unit is calculated; the splicing position is determined, and the splicing position is the data node corresponding to the smallest root mean square on the difference curve; The length of the optical fiber to be tested corresponding to the splicing position determines the target node of the optical fiber to be tested; the near-end event test result and the far-end event test result are generated, wherein the near-end event test result refers to the first The part corresponding to the target node from the beginning of the optical fiber under test in a test curve, and the remote event test result refers to the corresponding part from the target node to the end of the optical fiber under test in the second test curve section.

Among them, the preset length is usually set to twice the distance between two adjacent remote events.

As shown in Figure 5 (a) (b) (c), Figure 5 (a) (b) (c) respectively show the first test curve corresponding to the first pulse laser, and the second pulse laser corresponding The second test curve is the test curve obtained after splicing. Through the above method, the splicing point w corresponding to the target node W on the first test curve and the second test curve can be accurately determined, so as to clearly divide the test curve belonging to the proximal fiber on the first test curve and the test curve belonging to the second test curve. The test curve of the remote fiber. Furthermore, as shown in Figure 5(c), the test curve corresponding to the near-end fiber and the test curve corresponding to the far-end fiber can be spliced together to form a new test curve, so that the test curve and the fiber to be tested have more Strong correspondence and completeness make it easy for testers to observe and judge.

Example 12

In order to complete the optical fiber test method provided in Embodiments 1-4, as shown in FIG. 6, this embodiment provides an optical time domain reflectometer, including: a laser transmitter 2, a signal receiver 3, and a processor 4; The laser transmitter 2 is used to emit pulsed laser light according to the optical fiber testing method provided in Examples 1-4, the signal receiver 3 is used to receive the optical signal reflected by the optical fiber to be tested, and the processor 4 is used to process The optical signal received by the signal receiver 3 is processed into test data.

Specifically, the laser transmitter 2 emits pulsed laser signals of corresponding pulse width and power intensity in accordance with the computer instructions issued by the computer, server, etc., according to the method described in Examples 1-4, and an additional controller 1 may be used. As shown in Fig. 6, the controller 1 is used to send computer instructions to the laser transmitter 2 to control the laser transmitter 2 to emit pulsed laser signals according to the computer instructions. Preferably, an optical circulator can be provided at the port of the optical fiber to be tested to distinguish the incident signal from the reflected signal. The pulsed laser signal emitted by the laser transmitter passes through the optical circulator and enters the optical fiber to be tested for testing. The optical signal reflected by the optical circulator enters the signal receiver 3 through the optical circulator, and the signal receiver 3 can be a photodetector. . The processor 4 includes a transimpedance amplification unit, a linear amplification unit, an analog filter, an ADC (Analog-to-Digital Converter, analog-to-digital conversion) acquisition unit, and a logic processing unit. The processor 3 first converts the received optical signal The current signal is converted into a voltage signal with appropriate amplitude by the transimpedance amplifying unit and linear amplifying unit, the noise in the voltage signal is reduced through an analog filter, and the noise-reduced voltage signal is obtained by the ADC acquisition unit Converted into the corresponding digital signal, at this time, the logic processing unit can process the digital signal into displayable test data according to the logic operation. The processor 3 sends the generated test data to a computer, a server, etc., such as the controller 1 mentioned above, and then the controller 1 sends it to the display component of the OTDR for presentation to the tester; or the processor 3 directly The generated test data is sent to the display component of the OTDR to be presented to the tester.

In one implementation, the laser transmitter 2 emits pulsed laser light, wherein the pulse width of the pulsed laser light is smaller than that required for the optical signal to propagate between two adjacent proximal events in the proximal fiber of the fiber to be tested. time.

In an implementation manner, the laser transmitter 2 emits pulsed lasers, wherein the transmission distance of each pulsed laser within the corresponding sub-test time is greater than or equal to the preset test length.

In an implementation manner, after the processor 4 calculates the average value of all sub-test data and obtains the test result, according to the test result, it generates a test curve reflecting the test data corresponding to the different lengths of the optical fiber to be tested.

Among them, please refer to the description of embodiment 1-4 for the pulse laser and pulse laser emission mode corresponding to the optical time domain reflectometer provided in this embodiment, the specific processing method of the test result, and the beneficial effects, which will not be omitted here. Go into details.

When the test range of the optical time domain reflectometer provided in this embodiment is less than the length of the fiber to be tested, it can test the fiber of the preset test length by emitting multiple pulsed lasers with different test ranges, thereby effectively eliminating the influence of ghosting. , Make the test result more accurate.

Example 13

In order to complete the optical fiber testing method provided in Embodiments 5-11, as shown in FIG. 6, this embodiment provides an optical time domain reflectometer, including: a laser transmitter 2, a signal receiver 3, and a processor 4; The laser transmitter 2 is used to emit pulsed laser light according to the optical fiber testing method provided in Embodiments 5-11, the signal receiver 3 is used to receive the optical signal reflected by the optical fiber to be tested, and the processor 4 is used to process The optical signal received by the signal receiver 3 is processed into test data. This embodiment can use the optical time domain reflectometer with the same structure as the embodiment 12. The difference is that in order to complete different optical fiber test methods, different computer instructions (set different parameters) need to be input to the OTDR to make the laser transmitter 2. The signal receiver 3 and the processor 4 complete the corresponding work. The working principle of the OTDR provided in this application is the same as the OTDR provided in Embodiment 12, and will not be repeated here.

In one implementation, when the laser transmitter 2 emits a first pulsed laser within the first test time, the first pulsed laser corresponds to the first test range, and the first test range means that the optical signal is in the The distance traveled within the pulse interval of the first pulse laser, and the first test range is greater than or equal to the length of the optical fiber to be tested.

In an implementation manner, when the laser transmitter 2 emits multiple first pulse lasers within the first test time, each of the first pulse lasers corresponds to a second test range, and the second test range is an optical signal The distance traveled within the pulse interval of the first pulsed laser, wherein each of the second test ranges is different, and each of the second test ranges is greater than or equal to the length of the proximal optical fiber and less than The length of the optical fiber to be tested.

In an implementation manner, the difference between the second test ranges corresponding to the two first pulse lasers emitted by the laser transmitter 2 is at least greater than the distance between two adjacent proximal events.

In an implementation manner, the pulse width range selected by the laser reflector 2 is that the first pulse width is 100 ns to 800 ns, and the second pulse width is 10000 ns to 20000 ns.

In an implementation manner, the processor 4 generating the first test data includes: using each of the first pulse lasers to test in the corresponding sub-test time in the first test time to obtain the sub-test data; The average value of the sub-test data is the first test data.

In an implementation manner, generating the first test data and the second test data by the processor 4 includes: generating, according to the first test data, a first test curve reflecting test data corresponding to different lengths of the optical fiber to be tested; According to the second test data, a second test curve reflecting the test data corresponding to different lengths of the optical fiber to be tested is generated.

In an implementation manner, the processor 4 generating a near-end event test result and a far-end event test result includes: generating a near-end event test result according to a test curve corresponding to the near-end optical fiber in the first test curve, The remote event test result is generated according to the test curve corresponding to the remote optical fiber in the second test curve.

In an implementation manner, the processor 4 generates a near-end event test result according to the test curve corresponding to the near-end optical fiber in the first test curve, and according to the second test curve corresponding to the far-end optical fiber The test curve for generating a remote event test result includes: generating a difference curve between the first test curve and the second test curve; dividing the difference curve into a plurality of calculation units with a preset length; calculating the calculation The root mean square of all the values in the unit; determine the splicing position, the splicing position is the data node corresponding to the smallest root mean square on the differential curve; according to the length of the optical fiber to be tested corresponding to the splicing position, Determine the target node of the fiber to be tested; generate a near-end event test result and a far-end event test result, where the near-end event test result refers to the start of the fiber to be tested in the first test curve. For the part corresponding to the target node, the remote event test result refers to the part corresponding to the end of the optical fiber to be tested from the target node in the second test curve.

Among them, please refer to the description of embodiment 5-11 for the pulse laser and pulse laser emission mode corresponding to the optical time domain reflectometer provided in this embodiment, the specific processing method of the test result, and the beneficial effects, which will not be omitted here. Go into details.

When the optical time domain reflectometer provided in this embodiment tests the optical fiber to be tested, it can test the near-end events and the far-end events in a targeted manner, so that the test results are more accurate.

In the above embodiments, the computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, from which the computer-readable storage medium can be used via wired (for example, coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (for example, infrared, wireless, Microwave, etc.) to transmit to OTDR. The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center integrated with one or more available media. The usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state hard disk).

Claims

A method for optical fiber testing based on an optical time domain reflectometer, which is characterized in that it comprises:

The optical time domain reflectometer emits multiple pulsed lasers within a preset test time, wherein the pulse width of each pulsed laser is equal, and the test range corresponding to each pulsed laser is greater than or equal to that of the light. For the preset test length in the optical fiber to be tested connected to the time domain reflectometer, each of the pulsed lasers corresponds to a different test range, and the test range is the distance traveled by the optical signal within the pulse interval time of the pulsed laser;

Generating sub-test data, where the sub-test data refers to test data obtained by using each of the pulsed lasers to perform a test in a corresponding sub-test time within the preset test time;

Calculate the average value of the sub-test data to obtain the test result.
The method according to claim 1, wherein the pulse width of the pulsed laser is less than the time required for the optical signal to propagate between two adjacent proximal events in the proximal fiber in the fiber under test.
The method according to claim 1 or 2, wherein the transmission distance of each pulse laser in the corresponding sub-test time is greater than or equal to the preset test length.
The method according to any one of claims 1 to 3, wherein the calculating the average value of all sub-test data, after obtaining the test result, comprises:

According to the test result, a test curve reflecting the test data corresponding to different lengths of the optical fiber to be tested is generated.
A method for optical fiber testing based on an optical time domain reflectometer, which is characterized in that it comprises:

The optical time domain reflectometer emits one or more first pulse lasers with a first pulse width during the first test time, and emits a second pulse laser with a second pulse width during the second test time, wherein each The transmission distance of one of the first pulse lasers in the first test time is greater than or equal to the length of the proximal fiber in the fiber to be tested connected to the optical time domain reflectometer, and the first pulse width is less than The time required for the optical signal to propagate between two adjacent proximal events in the near-end optical fiber, and the transmission distance of the second pulsed laser within the second test time is greater than or equal to that of the optical fiber to be tested length;

Generate first test data and second test data, where the first test data refers to test data obtained by using the first pulsed laser to perform a test within the first test time, and the second test data is Refers to the test data obtained by using the second pulsed laser to perform a test within the second test time;

Generate a near-end event test result and a far-end event test result, where the near-end event test data refers to test data corresponding to the near-end optical fiber in the first test data, and the far-end event test result is Refers to the test data corresponding to the remote optical fiber in the optical fiber to be tested in the second test data.
The method according to claim 5, wherein when the optical time domain reflectometer emits a first pulsed laser within the first test time, the first pulsed laser corresponds to the first test range, and the first A test range is the distance that the optical signal travels within the pulse interval of the first pulsed laser, and the first test range is greater than or equal to the length of the optical fiber to be tested.
The method according to claim 5, wherein when the optical time domain reflectometer emits a plurality of first pulse lasers within the first test time, each of the first pulse lasers corresponds to a second test range, The second test range is the distance that the optical signal travels within the pulse interval of the first pulsed laser, wherein each of the second test ranges is different, and each of the second test ranges is greater than or equal to all of the second test ranges. The length of the proximal optical fiber is smaller than the length of the optical fiber to be tested.
The method according to claim 5 or 7, wherein the difference between the second test ranges corresponding to the two first pulse lasers is at least greater than the distance between two adjacent proximal events.
The method according to any one of claims 5-8, wherein the first pulse width is 100 ns to 800 ns, and the second pulse width is 10000 ns to 20000 ns.
The method according to claim 7 or 8, wherein said generating the first test data comprises:

Using each of the first pulse lasers to test in the corresponding sub-test time in the first test time to obtain sub-test data respectively;

The average value of all the sub-test data is calculated to obtain the first test data.
The method according to any one of claims 5-10, wherein said generating the first test data and the second test data comprises:

According to the first test data, a first test curve reflecting the test data corresponding to the different lengths of the optical fiber to be tested is generated; according to the second test data, a first test curve reflecting the test data corresponding to the different lengths of the optical fiber to be tested is generated 2. Test curve.
The method according to claim 11, wherein said generating a test result of a near-end event and a test result of a far-end event comprises:

The near-end event test result is generated according to the test curve corresponding to the near-end optical fiber in the first test curve, and the far-end event test result is generated according to the test curve corresponding to the far-end optical fiber in the second test curve.
The method according to claim 12, wherein said generating a near-end event test result according to a test curve corresponding to the proximal fiber in the first test curve, and generating a test result of a near-end event according to the test curve corresponding to the near-end optical fiber in the first test curve; The test curve corresponding to the remote fiber generates the remote event test results including:

Generating a difference curve between the first test curve and the second test curve;

Dividing the difference curve into a plurality of calculation units with a preset length;

Calculate the root mean square of all values in the calculation unit;

Determining a splicing position, where the splicing position is a data node corresponding to the smallest root mean square on the difference curve;

Determine the target node of the optical fiber to be tested according to the length of the optical fiber to be tested corresponding to the splicing position;

Generate a near-end event test result and a far-end event test result, where the near-end event test result refers to the portion corresponding to the target node from the beginning of the fiber to be tested in the first test curve, and the remote The end event test result refers to the part corresponding to the end of the optical fiber to be tested from the target node in the second test curve.
An optical time domain reflectometer, which is characterized by comprising: a laser transmitter, a signal receiver, and a processor; the laser transmitter is used to emit pulsed laser light according to the method of any one of claims 1-4, and The signal receiver is used to receive the optical signal reflected by the optical fiber to be tested, and the processor is used to process the optical signal received by the signal receiver into test data.
An optical time domain reflectometer, which is characterized by comprising: a laser transmitter, a signal receiver, and a processor; the laser transmitter is used to emit pulsed laser light according to the method of any one of claims 5-13, and The signal receiver is used to receive the optical signal reflected by the optical fiber to be tested, and the processor is used to process the optical signal received by the signal receiver into test data.
A computer program product containing instructions, wherein when the computer program product runs on an optical time domain reflectometer, the optical time domain reflectometer is caused to execute the method according to any one of claims 1-4.
A computer program product containing instructions, wherein when the computer program product runs on an optical time domain reflectometer, the optical time domain reflectometer is caused to execute the method according to any one of claims 5-13.