A time division multiple access based one-way optical fiber long distance measurement method and device

Abstract

The application discloses a kind of one-way optical fiber long distance measurement method and device based on time division multiple access, it is related to optical fiber measurement technical field, master station equipment time division multiple access sends electromagnetic wave signal of two time slots different wave band to slave station equipment, and synchronously obtains two-way electromagnetic wave signal transmission time difference value, the dispersion delay linear variation amount of two-way electromagnetic wave signal in preset optical fiber is calculated by preset method;Since the dispersion of optical fiber to different wavelength optical signal linearly increases with the increase of distance, based on the transmission time difference value and dispersion delay difference time variation resolution, the distance of optical fiber can be roughly calculated, since the carrier phase difference value also corresponds to the linear delay of dispersion, the carrier phase change rate is used again, the rough optical fiber distance between master station equipment and slave station equipment is improved in accuracy, so that the error is controlled in smaller range.The application solves the problem that long distance optical fiber one-way transmission signal cannot measure distance.

Description

Technical Field

[0001] This invention relates to the field of optical fiber measurement technology, and in particular to a method and apparatus for long-distance unidirectional optical fiber measurement based on time division multiple access. Background Technology

[0002] Currently, the most common long-distance fiber optic measurement technology is Optical Time Domain Reflectometry (OTDR). The principle involves sending light pulses into the fiber, analyzing the time difference and intensity changes of the reflected signal, and calculating the fiber length, loss, and fault location. This technology is suitable for long-distance measurements of 50-200 km, with positioning accuracy reaching the meter level. However, this technology requires bidirectional use on a single fiber; the transmitted optical signal needs to be reflected back to measure the distance. Since fiber optic links with optical fiber amplifiers (EDFA) cannot transmit bidirectionally, this method cannot be used.

[0003] Another method is optical frequency domain reflectance (OFDR). The principle is to achieve sub-meter spatial resolution by modulating the optical frequency and analyzing the phase difference of the reflected signal. The accuracy can reach the millimeter level, but the measurement distance is short, less than 10km. It is suitable for precision detection, but the transmitted optical signal needs to be reflected back in order to measure the distance. Unidirectional optical fiber cannot be used for measurement.

[0004] Therefore, there is an urgent need for a measurement method for long distances of unidirectional optical fibers to solve the above problems. Summary of the Invention

[0005] In view of this, this application provides a method and apparatus for long-distance measurement of unidirectional optical fiber based on time division multiple access, so as to solve the problem that the distance cannot be measured when transmitting signals unidirectionally over long distances in optical fiber in the prior art.

[0006] The first aspect of this application provides a method for long-distance unidirectional fiber optic measurement based on time-division multiple access, including:

[0007] The master station equipment sends electromagnetic wave signals in two time slots, and the two electromagnetic wave signals have different frequency bands.

[0008] After electro-optical conversion and coupling processing of the two electromagnetic wave signals, they are transmitted to the slave station equipment through a preset optical fiber;

[0009] After receiving the optical fiber signal and performing splitting and photoelectric conversion processing, the slave device obtains the transmission time difference between the two electromagnetic wave signals arriving at the slave device.

[0010] The linear variation of dispersion delay of the two electromagnetic wave signals in the preset optical fiber is calculated using a preset method.

[0011] Based on the transmission time difference and the linear change in dispersion delay, the fiber length between the master station equipment and the slave station equipment is calculated.

[0012] In one possible implementation of the first aspect, photoelectric conversion and coupling processing of the two electromagnetic wave signals includes:

[0013] The first electro-optic conversion module is used to perform electro-optic conversion processing on one electromagnetic wave signal to obtain one optical signal;

[0014] The second electro-optic conversion module is used to perform electro-optic conversion processing on another electromagnetic wave signal to obtain another optical signal;

[0015] Two optical signals are coupled into one optical signal using an optical fiber coupler.

[0016] In one possible implementation of the first aspect, the slave device receiving the optical fiber signal and performing optical splitting and photoelectric conversion processing includes:

[0017] The optical signal is split into two optical signals by the optical fiber coupler;

[0018] The first photoelectric conversion module is used to perform photoelectric conversion processing on one optical signal to obtain one electrical signal;

[0019] The second photoelectric conversion module is used to perform photoelectric conversion processing on the other optical signal to obtain another electrical signal.

[0020] In one possible implementation of the first aspect, the preset method includes:

[0021] The master station equipment sends the two electromagnetic wave signals to the slave station equipment with adjustable fiber optic transmission distance, where the adjustable fiber optic transmission distance is nd, n≥1;

[0022] The transmission time difference between the two electromagnetic wave signals reaching the slave device with an adjustable fiber transmission distance of d and reaching the slave device with an adjustable fiber transmission distance of nd is calculated sequentially, and is used as the difference in the linearity of the dispersion delay of the corresponding two electromagnetic wave signals.

[0023] The difference between all linear values ​​of dispersion delay of the two electromagnetic wave signals is fitted to obtain the resolution of dispersion delay difference time variation.

[0024] In one possible implementation of the first aspect, the preset method further includes:

[0025] The master station device sends the two electromagnetic wave signals to the slave station device at the initial optical fiber transmission distance, and the slave station device is referred to as the first slave station device. The initial optical fiber transmission distance is d.

[0026] The first slave device receives the broadcast message from the master device and reads the difference in carrier phase when the two electromagnetic wave signals arrive at the first slave device;

[0027] Add a distance md' to the initial fiber optic transmission distance, where d'≪d and m≥1;

[0028] After adding the md' distance to the initial optical fiber transmission distance, the difference in carrier phase when the two electromagnetic wave signals arrive at the first slave device is read sequentially.

[0029] The difference between all carrier phases when the two electromagnetic wave signals reach the first slave device is fitted to obtain the carrier phase change rate.

[0030] The dispersion delay difference time variation resolution and the carrier phase change rate constitute the linear variation of the dispersion delay.

[0031] In one possible implementation of the first aspect, calculating the fiber optic length between the master station equipment and the slave station equipment based on the transmission time difference and the linear change in dispersion delay includes:

[0032] Based on the transmission time difference, the difference in the linear values ​​of the dispersion delay of the two electromagnetic wave signals is obtained and denoted as the first linear value difference of dispersion delay.

[0033] Based on the first linear difference of dispersion delay and the time change resolution of the dispersion delay difference, the optical fiber distance between the master station equipment and the slave station equipment is calculated to be L1.

[0034] Based on the carrier phase change rate, the fiber length L0 traversed by a single carrier phase integer cycle is obtained.

[0035] Using L1 and L0, the integer ambiguity of the carrier phase containing a fraction is calculated;

[0036] The first fiber distance is calculated based on the integer part of the carrier phase integer ambiguity and L0; the second fiber distance is calculated based on the fractional part of the carrier phase integer ambiguity and the carrier phase change rate.

[0037] The sum of the first fiber optic distance and the second fiber optic distance is calculated and used as the fiber optic distance between the master station device and the slave station device.

[0038] In one possible implementation of the first aspect, the two electromagnetic wave signals are in the 1529.16 band and the 1560.61 band, respectively.

[0039] In one possible implementation of the first aspect, the preset optical fiber is a G652D optical fiber.

[0040] In one possible implementation of the first aspect, the frequency of the carrier signal corresponding to the two electromagnetic wave signals transmitted by the master station equipment is 1.5 GHz.

[0041] A second aspect of this application provides a time-division multiple access-based unidirectional fiber optic long-distance measurement device, comprising: a processor and a memory, the processor and the memory being connected via a communication bus; wherein, the processor is used to call and execute a program stored in the memory; the memory is used to store the program, the program being used to implement the time-division multiple access-based unidirectional fiber optic long-distance measurement method as provided in the first aspect of this application.

[0042] Its beneficial effects are as follows: This invention discloses a method and device for long-distance measurement of unidirectional optical fiber based on time-division multiple access. It measures the length of the optical fiber based on the principle that the dispersion of optical signals of different wavelengths increases linearly with distance. The master station equipment transmits electromagnetic wave signals of different time slots in two time slots via time-division multiple access. After electro-optical conversion and coupling processing, the signals are transmitted to the slave station equipment through optical fiber. The slave station equipment then performs beam splitting and photoelectric conversion to receive the two electromagnetic wave signals and simultaneously acquires the transmission time difference between the two electromagnetic wave signals. The two electromagnetic wave signals are then calculated using a preset method. The linear change in dispersion delay of a signal within a pre-defined optical fiber includes the time resolution of the dispersion delay difference and the carrier phase change rate. Since the dispersion of optical fibers for different wavelengths increases linearly with distance, the fiber distance can be roughly calculated based on this transmission time difference and the time resolution of the dispersion delay difference. Because the carrier phase difference also corresponds to the linear delay of dispersion, the accuracy of the approximate fiber distance between the master and slave stations is improved using the carrier phase change rate, thereby controlling the error in the calculated fiber distance within a small range. This invention not only solves the problem that the addition of an optical fiber amplifier during long-distance optical fiber signal transmission restricts fiber transmission to one direction, preventing distance measurement based on optical signal reflection, but also solves the problem of not being able to measure ultra-long fiber optic distances. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application 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 embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0044] Figure 1 This is a schematic flowchart of a unidirectional fiber optic long-distance measurement method based on time division multiple access provided in an embodiment of this application;

[0045] Figure 2 This is a schematic diagram of electromagnetic wave signal transmission in an embodiment of this application. Detailed Implementation

[0046] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0048] Example 1

[0049] In existing technologies, long-distance fiber optic measurements generally employ optical time-domain reflectometry (OTDR) and optical frequency-domain reflectometry (OFDR). OTDR works by sending optical pulses into the fiber, analyzing the time difference and intensity changes of the reflected signals, and calculating fiber length, loss, and fault location. OFDR achieves sub-meter spatial resolution by modulating the optical frequency and analyzing the phase difference of the reflected signals. OTDR requires bidirectional use on a single fiber; the transmitted optical signal must be reflected back to measure the distance. However, in links with optical fiber amplifiers (EDFAs), bidirectional transmission is not possible. It's important to note that fiber optic communication experiences a power loss of 22dB / 100km; fiber optic transmission links exceeding 300km require EDFAs to amplify the optical signal power. With an EDFA, the fiber can only transmit signals unidirectionally. OFDR, while achieving millimeter-level accuracy, has a shorter measurement distance (less than 10km), making it suitable for precision testing. Again, the transmitted optical signal must be reflected back to measure the distance, which is impossible with unidirectional fiber optics.

[0050] Therefore, this application provides a unidirectional fiber optic long-distance measurement method based on time division multiple access, such as... Figure 1 As shown, it includes:

[0051] The master station equipment sends electromagnetic wave signals in two time slots, and the two electromagnetic wave signals have different frequency bands.

[0052] After electro-optical conversion and coupling processing of the two electromagnetic wave signals, they are transmitted to the slave station equipment through a preset optical fiber;

[0053] After receiving the optical fiber signal and performing splitting and photoelectric conversion processing, the slave device obtains the transmission time difference between the two electromagnetic wave signals arriving at the slave device.

[0054] The linear variation of dispersion delay of the two electromagnetic wave signals in the preset optical fiber is calculated using a preset method.

[0055] Based on the transmission time difference and the linear change in dispersion delay, the fiber length between the master station equipment and the slave station equipment is calculated.

[0056] Please refer to the following: Figure 2 , Figure 2 This is a schematic diagram of electromagnetic wave signal transmission in an embodiment of this application. Two electromagnetic wave signals are transmitted through the master station equipment. The corresponding carrier signal is 1.5 GHz, and the signal modulated on the carrier is 40.92 MHz. The broadcast message includes time slot information and a broadcast timestamp. The interval between the two time slots is 100 µs, and the broadcast signal repeats once every 1 ms. The signals from the two time slots are split into two paths by a radio frequency switch. The two electromagnetic wave signals are transmitted in the 1529.16 GHz band and the 1560.61 GHz band, respectively. The above section describes the basic parameter settings when the master station equipment transmits signals. These settings can be adjusted according to actual conditions, and this embodiment does not impose specific limitations.

[0057] The two electromagnetic wave signals transmitted by the time-division multiple access equipment at the main station are converted into optical signals by an electro-optical conversion module in the 1529.16 band and an electro-optical conversion module in the 1560.61 band, respectively. Then, the two optical signals are coupled into one optical signal by an optical fiber coupler. This optical signal is transmitted over a long distance in G652D optical fiber and amplified by an optical fiber amplifier EDFA in the middle.

[0058] In this process, after the optical signal is transmitted to the slave device via a pre-set optical fiber, a fiber optic coupler is used to couple one optical signal into two optical signals. Then, photoelectric conversion modules in the 1529.16 band and 1560.61 band are used respectively to perform photoelectric conversion, converting the two optical signals into two electromagnetic wave signals. The transmission time difference between the two electromagnetic wave signals arriving at the slave device is then obtained. For example, if the transmission time of one electromagnetic wave signal is... The other electromagnetic wave signal was transmitted at the time of... (Δt is the interval time), the time when one electromagnetic wave signal arrives at the slave device is The other electromagnetic wave signal arrives at the slave device at the following time: Then the time difference between the two electromagnetic wave signals arriving at the slave device is... .

[0059] Since the dispersion of optical fiber for different wavelengths of light signals increases linearly with increasing distance, a preset method is used to calculate the linear change in dispersion delay of two electromagnetic wave signals in the preset optical fiber. The linear change in dispersion delay includes the time change resolution of the dispersion delay difference and the carrier phase change rate.

[0060] The preset method for solving the resolution of the dispersion delay difference time variation includes: the master station equipment sends the two electromagnetic wave signals to the slave station equipment with an adjustable fiber optic transmission distance of nd, where n≥1; for example, d is 10km. After the slave station equipment receives the electromagnetic wave signals from two different time slots, it reads the transmission time of the signal from the broadcast message, subtracts the transmission time of the master station equipment from the time it arrives at the slave station equipment to calculate the arrival time difference of each time slot, and then calculates the transmission time difference of the two electromagnetic waves by subtracting the arrival time difference of the two time slots, i.e., the dispersion delay linearity. The difference in values ​​is recorded; the above steps are repeated, adding another 10km to the 10km transmission fiber, and the difference in the linear values ​​of dispersion delay of the two electromagnetic waves in the 20km fiber is recorded, until the fiber length reaches 500km. At this point, 50 differences in the linear values ​​of dispersion delay are recorded. Theoretically, these 50 data points should increase linearly, but due to errors in measurement or actual adjustment of fiber distance, these 50 data points are fitted to calculate that the time change of the fiber is 1.1s for every 10km increase, i.e., the resolution of the time change of the dispersion delay difference is 0.91km / 0.1s. It should be noted that the above data is only an explanation of how to solve the resolution of the time change of the dispersion delay difference, and can be adjusted according to the actual situation. This embodiment does not impose specific limitations.

[0061] The master station sends two electromagnetic wave signals to the first slave station. The initial fiber optic transmission distance between the master station and the first slave station is 10km. After receiving the electromagnetic wave signals from two different time slots, the first slave station reads the carrier phase of the two time slot signals when they arrive from the broadcast message. Since only the change within one cycle can be read, the number of whole cycles that the two electromagnetic wave signals experience when passing through 10km of fiber is unknown. Therefore, the difference in carrier phase is calculated by reading the carrier phase values ​​of the two time slots. Then, an additional 10m of fiber is added to the 10km transmission fiber, i.e., d' is 10m, and the difference in carrier phase is calculated again. The above steps are repeated, further increasing the fiber distance by 10m, and 50 differences in carrier phase are recorded. Then, these 50 differences in carrier phase are fitted. When the fiber distance increases by 10m, the difference in carrier phase increases by 0.009 cycles, i.e., the carrier phase change resolution is 10m / 0.009 cycles. At the same time, using this carrier phase change resolution, the fiber length that one whole cycle of a carrier phase passes through can be calculated to be 1111.1m.

[0062] The process involves the slave station receiving fiber optic signals and calculating the fiber length. The difference in the transmission time difference between the two electromagnetic wave signals is used to obtain the difference in the linearity of the dispersion delay. Based on the time variation resolution of this dispersion delay difference, a coarse fiber distance is calculated. This coarse fiber distance is then divided by the fiber length traversed in one integer carrier phase cycle to calculate the carrier phase integer ambiguity, which contains a fractional part. The integer part of this carrier phase integer ambiguity represents the number of integer carrier phase cycles, while the fractional part represents data where the carrier phase is less than one cycle (e.g., 0.5). (Representing half a cycle); using the integer part and the fiber length traversed during the integer cycle of the carrier phase (1111.1m), the fiber length traversed by the integer part can be calculated, which is the first fiber distance. Using the fractional part and the carrier phase change resolution (10m / 0.009 cycles), the fiber length traversed by the fractional part can be calculated, which is the second fiber distance. Finally, the fiber length traversed by the integer part and the fiber length traversed by the fractional part are added together, that is, the sum of the first fiber distance and the second fiber distance is calculated, which gives the fiber length between the master station equipment and the slave station equipment.

[0063] This embodiment aims to provide a long-distance optical fiber unidirectional transmission measurement method based on time division multiple access. It utilizes the linear increase in dispersion of different wavelengths in optical fiber as the distance increases to measure the length. This not only solves the problem that adding EDFA to long-distance optical fiber signal transmission causes the optical fiber to only transmit in one direction and cannot rely on optical signal reflection for distance measurement, but also solves the problem that ultra-long optical fiber distances cannot be measured. Two-station cascade can measure distances of over 500km, and multi-level base station cascade can theoretically achieve infinite length unidirectional optical fiber length measurement, and the measurement error can be controlled within a small range.

[0064] In some embodiments, photoelectric conversion and coupling processing of the two electromagnetic wave signals includes:

[0065] The first electro-optic conversion module is used to perform electro-optic conversion processing on one electromagnetic wave signal to obtain one optical signal;

[0066] The second electro-optic conversion module is used to perform electro-optic conversion processing on another electromagnetic wave signal to obtain another optical signal;

[0067] Two optical signals are coupled into one optical signal using an optical fiber coupler.

[0068] In some embodiments, the slave device receiving the fiber optic signal and performing splitting and photoelectric conversion processing includes:

[0069] The optical signal is split into two optical signals by the optical fiber coupler;

[0070] The first photoelectric conversion module is used to perform photoelectric conversion processing on one optical signal to obtain one electrical signal;

[0071] The second photoelectric conversion module is used to perform photoelectric conversion processing on the other optical signal to obtain another electrical signal.

[0072] In some embodiments, the preset method includes:

[0073] The master station equipment sends the two electromagnetic wave signals to the slave station equipment with adjustable fiber optic transmission distance, where the adjustable fiber optic transmission distance is nd, n≥1;

[0074] The transmission time difference between the two electromagnetic wave signals reaching the slave device with an adjustable fiber transmission distance of d and reaching the slave device with an adjustable fiber transmission distance of nd is calculated sequentially, and is used as the difference in the linearity of the dispersion delay of the corresponding two electromagnetic wave signals.

[0075] The difference between all linear values ​​of dispersion delay of the two electromagnetic wave signals is fitted to obtain the resolution of dispersion delay difference time variation.

[0076] In some embodiments, the preset method further includes:

[0077] The master station device sends the two electromagnetic wave signals to the slave station device at the initial optical fiber transmission distance, and the slave station device is referred to as the first slave station device. The initial optical fiber transmission distance is d.

[0078] The first slave device receives the broadcast message from the master device and reads the difference in carrier phase when the two electromagnetic wave signals arrive at the first slave device;

[0079] Add a distance md' to the initial fiber optic transmission distance, where d'≪d and m≥1;

[0080] After adding the md' distance to the initial optical fiber transmission distance, the difference in carrier phase when the two electromagnetic wave signals arrive at the first slave device is read sequentially.

[0081] The difference between all carrier phases when the two electromagnetic wave signals reach the first slave device is fitted to obtain the carrier phase change rate.

[0082] The dispersion delay difference time variation resolution and the carrier phase change rate constitute the linear variation of the dispersion delay.

[0083] In some embodiments, calculating the fiber optic length between the master station device and the slave station device based on the transmission time difference and the linear change in dispersion delay includes:

[0084] Based on the transmission time difference, the difference in the linear values ​​of the dispersion delay of the two electromagnetic wave signals is obtained and denoted as the first linear value difference of dispersion delay.

[0085] Based on the first linear difference of dispersion delay and the time change resolution of the dispersion delay difference, the optical fiber distance between the master station equipment and the slave station equipment is calculated to be L1.

[0086] Based on the carrier phase change rate, the fiber length L0 traversed by a single carrier phase integer cycle is obtained.

[0087] Using L1 and L0, the integer ambiguity of the carrier phase containing a fraction is calculated;

[0088] The first fiber distance is calculated based on the integer part of the carrier phase integer ambiguity and L0; the second fiber distance is calculated based on the fractional part of the carrier phase integer ambiguity and the carrier phase change rate.

[0089] The sum of the first fiber optic distance and the second fiber optic distance is calculated and used as the fiber optic distance between the master station device and the slave station device.

[0090] In some embodiments, the two electromagnetic wave signals are in the 1529.16 band and the 1560.61 band, respectively.

[0091] In some embodiments, the preset optical fiber is a G652D optical fiber.

[0092] In some embodiments, the frequency of the carrier signal corresponding to the two electromagnetic wave signals sent by the master station device is 1.5 GHz.

[0093] Example 2

[0094] Based on the time-division multiple access (TDMA)-based long-distance unidirectional fiber optic measurement method provided in Embodiment 1 of this application, correspondingly, Embodiment 2 of this application also provides a time-division multiple access-based long-distance unidirectional fiber optic measurement device, comprising:

[0095] The processor and memory are connected via a communication bus; wherein the processor is used to call and execute a program stored in the memory; the memory is used to store the program, which is used to implement a unidirectional fiber optic long-distance measurement method based on time division multiple access as provided in the first aspect of this application.

[0096] The specific principle and execution process of the unidirectional fiber long-distance measurement device based on time division multiple access disclosed in Embodiment 2 of this application are the same as the unidirectional fiber long-distance measurement method based on time division multiple access disclosed in Embodiment 1 of this application. Please refer to the corresponding part of the unidirectional fiber long-distance measurement method based on time division multiple access disclosed in Embodiment 1 of this application. It will not be repeated here.

[0097] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computing software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0098] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0099] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for long-distance unidirectional optical fiber measurement based on time-division multiple access, characterized in that, include: The master station equipment sends electromagnetic wave signals in two time slots, and the two electromagnetic wave signals have different frequency bands. After electro-optical conversion and coupling processing of the two electromagnetic wave signals, they are transmitted to the slave station equipment through a preset optical fiber; After receiving the optical fiber signal and performing splitting and photoelectric conversion processing, the slave device obtains the transmission time difference between the two electromagnetic wave signals arriving at the slave device. The linear variation of dispersion delay of the two electromagnetic wave signals in the preset optical fiber is calculated using a preset method. Based on the transmission time difference and the linear change in dispersion delay, the length of the optical fiber between the master station equipment and the slave station equipment is calculated. The preset method includes: The master station equipment sends the two electromagnetic wave signals to the slave station equipment with adjustable fiber optic transmission distance, where the adjustable fiber optic transmission distance is nd, n≥1; The transmission time difference between the two electromagnetic wave signals reaching the slave device with an adjustable fiber transmission distance of d and reaching the slave device with an adjustable fiber transmission distance of nd is calculated sequentially, and is used as the difference in the linearity of the dispersion delay of the corresponding two electromagnetic wave signals. The difference between all linear values ​​of dispersion delay of the two electromagnetic wave signals is fitted to obtain the resolution of the time change of dispersion delay difference. The preset method further includes: The master station device sends the two electromagnetic wave signals to the slave station device at the initial optical fiber transmission distance, and the slave station device is referred to as the first slave station device. The initial optical fiber transmission distance is d. The first slave device receives the broadcast message from the master device and reads the difference in carrier phase when the two electromagnetic wave signals arrive at the first slave device; Add a distance md' to the initial fiber optic transmission distance, where d'≪d and m≥1; After adding the md' distance to the initial optical fiber transmission distance, the difference in carrier phase when the two electromagnetic wave signals arrive at the first slave device is read sequentially. The difference between all carrier phases when the two electromagnetic wave signals reach the first slave device is fitted to obtain the carrier phase change rate. The dispersion delay difference time variation resolution and the carrier phase change rate constitute the linear variation of the dispersion delay; Based on the transmission time difference and the linear change in dispersion delay, the calculation of the fiber optic length between the master station equipment and the slave station equipment includes: Based on the transmission time difference, the difference in the linear values ​​of the dispersion delay of the two electromagnetic wave signals is obtained and denoted as the first linear value difference of dispersion delay. Based on the first linear difference of dispersion delay and the time change resolution of the dispersion delay difference, the optical fiber distance between the master station equipment and the slave station equipment is calculated to be L1. Based on the carrier phase change rate, the fiber length L0 traversed by a single carrier phase integer cycle is obtained. Using L1 and L0, the integer ambiguity of the carrier phase containing a fraction is calculated; The first fiber distance is calculated based on the integer part of the carrier phase integer ambiguity and L0; the second fiber distance is calculated based on the fractional part of the carrier phase integer ambiguity and the carrier phase change rate. The sum of the first fiber optic distance and the second fiber optic distance is calculated and used as the fiber optic distance between the master station device and the slave station device.

2. The method for long-distance unidirectional fiber optic measurement based on time-division multiple access according to claim 1, characterized in that, The photoelectric conversion and coupling processing of the two electromagnetic wave signals includes: The first electro-optic conversion module is used to perform electro-optic conversion processing on one electromagnetic wave signal to obtain one optical signal; The second electro-optic conversion module is used to perform electro-optic conversion processing on another electromagnetic wave signal to obtain another optical signal. Two optical signals are coupled into one optical signal using an optical fiber coupler.

3. The method for long-distance unidirectional fiber optic measurement based on time-division multiple access according to claim 2, characterized in that, The slave station equipment receives optical fiber signals and performs optical splitting and photoelectric conversion processing, including: The optical signal is split into two optical signals by the optical fiber coupler; The first photoelectric conversion module is used to perform photoelectric conversion processing on one optical signal to obtain one electrical signal; The second photoelectric conversion module is used to perform photoelectric conversion processing on the other optical signal to obtain another electrical signal.

4. The method for long-distance unidirectional optical fiber measurement based on time-division multiple access according to claim 1, characterized in that, The two electromagnetic wave signals are in the 1529.16 band and the 1560.61 band, respectively.

5. The method for long-distance unidirectional fiber optic measurement based on time-division multiple access according to claim 1, characterized in that, The preset optical fiber is G652D optical fiber.

6. The method for long-distance unidirectional optical fiber measurement based on time division multiple access according to claim 1, characterized in that, The frequency of the carrier signal corresponding to the two electromagnetic wave signals sent by the master station equipment is 1.5 GHz.

7. A unidirectional fiber optic long-distance measurement device based on time division multiple access, characterized in that, include: A processor and a memory are connected via a communication bus; wherein the processor is used to call and execute a program stored in the memory; The memory is used to store a program for implementing a unidirectional fiber optic long-distance measurement method based on time division multiple access as described in any one of claims 1-6.

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