A multi-channel telemetry optical fiber sensing system and method

Abstract

The present invention discloses a multi-channel telemetry optical fiber sensing system, comprising a pulse light source system and a phase demodulation module, wherein the pulse light source system and the phase demodulation module are connected through optical cable communication; further comprising N circulators, wherein N is a positive integer ≥ 2; the N circulators are sequentially arranged in a parallel or series structure along the transmission direction of the optical cable; for each circulator, one end of the circulator is used to input a pulse light signal, and the two ends of each circulator are connected to a sensing optical fiber, and the pulse light signal generates a Rayleigh scattered light signal during the transmission process of the sensing optical fiber, which enters through the 2nd port of the circulator in the reverse direction of the transmission direction of the pulse light signal, is output from the 3rd port, and finally enters the phase demodulation module through the detection optical fiber. The present invention combines the circulator with the sensing optical fiber, and the repetition frequency of the original limit light pulse signal can be increased by N times, thereby increasing the upper limit of the detection phase change signal by N times, and can realize the use of high repetition frequency pulse light under the premise of long-distance detection.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing technology, and in particular to an optical fiber sensing system and method for multi-channel telemetry. Background Art

[0002] With the continuous advancement of optical fiber technology, optical fiber sensing technology has been applied and developed in many fields. Among them, distributed optical fiber sensing is unique in sensing technology. It integrates transmission and sensing, and can achieve high-density temperature, strain, vibration, and sound wave fully distributed measurement for hundreds of kilometers. It has irreplaceable advantages and is therefore widely used. In traditional distributed vibration sensing systems, when the sensing optical fiber is subjected to a vibration signal of a certain frequency, the signal can be demodulated by detecting the phase change of the backscattered light signal light received by the vibration sensing optical fiber.

[0003] In the traditional distributed fiber optic vibration sensing system, an adjustable pulse light source injects pulse light into the sensing fiber, and the detector demodulates the signal according to the phase change of the Rayleigh scattered light signal by detecting the backscattered light signal. In this system, in order to avoid interference between the injected light pulse signal and the backscattered light signal, only one pulse light is allowed to exist in the entire sensing fiber at the same time. Therefore, this directly leads to the repetition frequency of the pulse light being inversely proportional to the length of the sensing fiber, making it impossible to use pulse light with a high repetition frequency in the case of long-distance detection. However, the repetition frequency of the pulse light directly determines the upper frequency limit of the signal to be measured. Therefore, the traditional distributed vibration sensing system cannot use pulse light with a high repetition frequency under the premise of long-distance detection. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the traditional distributed vibration sensing system cannot use high repetition frequency pulse light under the premise of long-distance detection. The present invention provides a multi-channel telemetry optical fiber sensing system and method to solve the above problem.

[0005] The present invention is achieved through the following technical solutions:

[0006] A multi-channel telemetry optical fiber sensing system, comprising a pulse light source system and a phase demodulation module, wherein the pulse light source system and the phase demodulation module are connected via optical cable communication, and characterized in that it also comprises N circulators, where N is a positive integer ≥ 2; the N circulators are arranged in sequence along the optical cable transmission direction, and the arrangement structure of the N circulators includes series connection or parallel connection;

[0007] For each circulator, end 1 of the circulator is used to input the pulse light signal, and end 2 of each circulator is connected to the sensing optical fiber. During the transmission of the pulse light signal through the sensing optical fiber, a Rayleigh scattered light signal is generated, which enters through port 2 of the circulator in the reverse direction of the transmission direction of the pulse light signal and is output from port 3. Finally, it enters the phase demodulation module through the detection optical fiber. In addition, only one pulse light can exist at the same time in the same section of sensing optical fiber.

[0008] Furthermore, along the overall transmission direction of the optical cable, the distances between any two adjacent circulators are equal.

[0009] Furthermore, along the overall transmission direction of the optical cable, the lengths of the sensing optical fibers between two adjacent circulators are equal.

[0010] Furthermore, each circulator is connected to the phase demodulation module via an independent detection optical fiber; the difference between the length of the detection optical fiber used to connect the Nth circulator and the phase demodulation module and the length of the detection optical fiber used to connect the N-1th circulator and the phase demodulation module is equal.

[0011] Furthermore, when N circulators are arranged in a series structure: they also include N wave splitters, N optical isolators and N combiners; one wave splitter, one circulator, one optical isolator and one combiner are used as one structural unit, with a total of N structural units; along the transmission direction, in each structural unit, the wave splitter is located at the upstream end, the combiner is located at the downstream end, and the circulator and optical isolator are connected in parallel between the wave splitter and the combiner; the N structural units are connected in series in sequence through the sensing optical fiber along the transmission direction, the wave splitter of the first structural unit is connected to the pulse light source system, and the wave splitter of the Nth structural unit is connected to the combiner of the N-1th structural unit through the sensing optical fiber.

[0012] Further, port 1 of the first wave splitter is connected to the pulse light source system, port 2 is connected to the first optical isolator and then connected to port 2 of the first wave combiner; port 3 of the first wave splitter is connected to port 1 of the first circulator, port 2 of the first circulator is connected to port 3 of the first wave combiner, and port 1 of the first wave combiner is connected to the first sensing optical fiber; port 1 of the Nth wave splitter is connected to port 1 of the (N-1)th wave combiner through the (N-1)th sensing optical fiber, port 2 is connected to port 2 of the Nth wave combiner after being connected to the Nth optical isolator, port 3 is connected to port 1 of the Nth circulator, port 2 of the Nth circulator is connected to port 3 of the Nth wave combiner, and the Nth circulator is connected to the Nth sensing optical fiber; and ports 3 of each circulator are connected to the phase demodulation module through their respective detection optical fibers.

[0013] Furthermore, when N circulators are arranged in a parallel structure: a splitter is also included; the 1' port of the splitter is connected to the pulse light source system as an input port, the splitter also has N ports as output ports, and each is respectively connected to the 1 port of a corresponding circulator, the 2 port of the circulator is connected to the sensing optical fiber, and the 3 port is connected to the phase demodulation module through the Nth detection optical fiber.

[0014] Furthermore, it also includes N optical fiber amplifiers and N delay optical fibers; port 1 of the Nth circulator is connected to the Nth output port of the splitter through the Nth optical fiber amplifier and the Nth delay optical fiber in sequence.

[0015] A multi-channel telemetry optical fiber sensing method, using a multi-channel telemetry optical fiber sensing system with a series structure; the transmission process includes the following steps:

[0016] Step 1, mixed light transmission:

[0017] a. The mixed light of the pulse signal light and the Raman pump light emitted by the pulse light source system is separated by the first wave splitter, wherein the Raman pump light is output from port 2, transmitted to port 2 of the first combiner through the first optical isolator, and then mixed with the pulse light signal output from port 3, entering through port 1 of the first circulator, and entering port 3 of the first combiner after being output from port 2; the mixed light is transmitted in the first sensing optical fiber, and Rayleigh scattered light signal is generated during the transmission process, and is output through ports 2 and 3 of the first combiner in the reverse direction of the transmission direction of the pulse light signal, wherein the Rayleigh scattered light signal coming out of port 2 is blocked by the optical isolator and cannot be transmitted further, and the Rayleigh scattered light signal coming out of port 3 enters through port 2 of the first circulator, is output from port 3, and enters the phase demodulation module through the first detection optical fiber;

[0018] b. Since the first sensing optical fiber is connected to the wave splitter of the second structural unit, the mixed light in the first sensing optical fiber continues to be transmitted forward and is separated by the second wave splitter, wherein the Raman pump light is output from port 2, transmitted to port 2 of the second combiner via the second optical isolator, and then mixed with the pulse light signal output from port 3, entering through port 1 of the second circulator, and entering port 3 of the second combiner after being output from port 2; it is transmitted in the second sensing optical fiber, and a Rayleigh scattered light signal is generated during the transmission process, which is output through ports 2 and 3 of the second combiner in the reverse direction of the transmission direction of the pulse light signal, wherein the Rayleigh scattered light signal coming out of port 2 is blocked by the optical isolator and cannot be transmitted further, and the Rayleigh scattered light signal coming out of port 3 enters through port 2 of the second circulator, is output from port 3, and enters the phase demodulation module via the second sensing optical fiber;

[0019] c. The above transmission process is extended to the Nth structural unit, thereby realizing the detection of long-distance optical pulse signals under high repetition frequency;

[0020] Step 2, pulse signal processing: After receiving the complete Rayleigh scattering signal, the phase demodulation module performs splicing processing to restore the vibration conditions within the entire detection range.

[0021] A multi-channel telemetry optical fiber sensing method, using a multi-channel telemetry optical fiber sensing system with a parallel structure; the transmission process includes the following steps:

[0022] Step 1, mixed light transmission:

[0023] a. The mixed light of the pulse signal light and the fully pumped light emitted by the pulse light source system is divided into N paths by a splitter. The first mixed light is output from port 1 of the splitter, transmitted in the first delay optical fiber, passes through the first optical fiber amplifier, enters from port 1 of the first circulator, outputs from port 2, and is transmitted in the first sensing optical fiber. Rayleigh scattered light signals are generated during the transmission process, enter through port 2 of the first circulator in the reverse direction of the transmission direction of the pulse light signal, output from port 3, and enter the phase demodulation module through the first detection optical fiber;

[0024] b. The second mixed light is output from port 2 of the splitter, transmitted in the second delay fiber, passes through the second EDFA, enters from port 1 of the second circulator, outputs from port 2, and is transmitted in the second sensing fiber. During the transmission, a Rayleigh scattered light signal is generated, which enters from port 2 of the second circulator in the reverse direction of the transmission direction of the pulse light signal, outputs from port 3, and enters the phase demodulation module through the second detection fiber.

[0025] c. The above transmission process is extended to the Nth circulator, thereby realizing the detection of long-distance optical pulse signals at a high repetition frequency;

[0026] Step 2, pulse signal processing: After receiving the complete Rayleigh scattering signal, the phase demodulation module performs splicing processing to restore the vibration conditions within the entire detection range.

[0027] The length of the probe is equal to the spacing between adjacent circulators multiplied by the number of circulators.

[0028] The present invention has the following advantages and beneficial effects:

[0029] 1. The present invention uses a circulator and a combination of a circulator and a sensing optical fiber to respectively apply the pulsed optical signal generated by the pulsed light source to each section of the sensing optical fiber, and the generated backscattered Rayleigh optical signal enters through the 2-port of the circulator to which it belongs in the reverse direction of the optical pulse transmission direction, and then outputs from the 3-port, and is finally transmitted to the signal demodulation module along the optical fiber. The repetition frequency of the optical pulse signal in the sensing optical fiber is greatly improved compared with the repetition frequency of the optical pulse signal in the traditional distributed sensing system. According to Nywest's sampling law, the greater the sampling rate, the higher the frequency of the seismic signal that can be detected and demodulated, which increases the upper limit of the signal frequency that can be detected by the system and further improves the overall signal-to-noise ratio of the system;

[0030] 2. The present invention directly and greatly increases the upper frequency limit of the detectable signal phase change, so that the distributed sensing system can use high repetition frequency optical pulse signal detection while detecting over long distances;

[0031] 3. The invention provided by the present invention can adjust the number and position of circulators set in the optical cable according to actual application requirements such as the length of the detection well and the resolution of the detection data, shorten the interval between two adjacent circulators, increase the repetition frequency of the pulse light, and ensure that only one beam of pulse light exists at the same time in the same section of the sensing optical fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0033] Figure 1 The invention is a multi-channel telemetry optical fiber sensing system, wherein the circulators are connected in series; Figure 1 Marks and corresponding parts names: a-pulse light source system, b-phase demodulation module; 1 is the first splitter, 5 is the second splitter, until (4n-3) is the Nth splitter; 2 is the first combiner, 6 is the second combiner, until (4n-2) is the Nth combiner; 3 is the first optical isolator, 7 is the second optical isolator, until (4n-1) is the Nth optical isolator; 4 is the first circulator, 8 is the second circulator, until 4n is the Nth circulator; 1' is the first sensor Optical fiber, 2' is the second sensing optical fiber, until n' is the Nth sensing optical fiber; 1" is the first detection optical fiber, 2" is the second detection optical fiber, until n" is the Nth detection optical fiber; P1 is port 1 of the wave splitter, P2 is port 2 of the wave splitter, and P3 is port 3 of the wave splitter; P1' is port 1 of the wave combiner, P2' is port 2 of the wave combiner, and P3' is port 3 of the wave combiner; P1" is port 1 of the circulator, P2" is port 2 of the circulator, and P3" is port 3 of the circulator.

[0034] Figure 2The optical fiber sensing system of the present invention is a multi-channel telemetry system, wherein the circulators are connected in parallel; Figure 2 The symbols and corresponding parts names are: a-pulse light source system, b-phase demodulation module, c-splitter; 1 is the first fiber amplifier; 3 is the second fiber amplifier, until (2n-3) is the (n-1)th fiber amplifier, (2n-1) is the Nth fiber amplifier; 2 is the first circulator, 4 is the second circulator, until (2n-2) is the (N-1)th circulator, 2n is the Nth circulator; 1' is the first delay fiber, 2' is the second delay fiber, until (n-1)' is the (N-1) delay fiber, n' is the Nth delay fiber; 1" is the 1st sensing fiber, 2" is the 2nd sensing fiber, until (n-1)" is the (N-1) sensing fiber, n" is the Nth sensing fiber; 1"' is the 1st detection fiber, 2"' is the 2nd detection fiber, until (n-1)"' is the (N-1) detection fiber, n"' is the Nth detection fiber; P0 is the 1' port of the splitter, which serves as the input port; P1 is the 1 port of the splitter, P2 is the 2 port of the splitter, until P (n-1) is the N-1 port of the splitter, P n is the N port of the splitter; P1' is the 1 port of the circulator, P2' is the 2 port of the circulator, and P3' is the 3 port of the circulator. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0036] Example 1

[0037] This embodiment provides a multi-channel telemetry optical fiber sensing system, including a pulse light source system, a phase demodulation module and N circulators, the pulse light source system and the phase demodulation module are connected by optical cable communication, N is a positive integer ≥ 2; the N circulators are arranged in sequence along the transmission direction of the optical cable, and the arrangement structure of the N circulators includes series or parallel connection. For each circulator, one end of the circulator is used to input a pulse light signal, and the two ends of each circulator are connected to the sensing optical fiber. The pulse light signal generates a Rayleigh scattered light signal during the transmission of the sensing optical fiber, which enters through the 2nd port of the circulator in the reverse direction of the transmission direction of the pulse light signal and is output from the 3rd port, and finally enters the phase demodulation module through the detection optical fiber, and at most only one beam of pulse light exists in the same section of the sensing optical fiber at the same time.

[0038] In addition, along the overall transmission direction of the optical cable, the distance between any two adjacent circulators is equal; along the overall transmission direction of the optical cable, the length of the sensing optical fiber between any two adjacent circulators is equal; each circulator is connected to the phase demodulation module through an independent detection optical fiber; the length of the detection optical fiber used to connect the Nth circulator and the phase demodulation module is equal to the length of the detection optical fiber used to connect the N-1th circulator and the phase demodulation module.

[0039] Example 2

[0040] The present embodiment provides a multi-channel telemetry optical fiber sensing system, which is further improved on the basis of Embodiment 1. When N circulators are arranged in a series structure: it also includes N wave splitters, N optical isolators and N combiners; one wave splitter, one circulator, one optical isolator and one combiner are used as one structural unit, with a total of N structural units; along the transmission direction, in each structural unit, the wave splitter is located at the upstream end and the combiner is located at the downstream end, and the circulator optical isolator is connected in parallel between the wave splitter and the combiner; the N structural units are connected in series in sequence through the sensing optical fiber along the transmission direction, the wave splitter of the first structural unit is connected to the pulse light source system, and the wave splitter of the Nth structural unit is connected to the combiner of the N-1th structural unit through the sensing optical fiber.

[0041] Specifically, port 1 of the first wave splitter is connected to the pulse light source system, port 2 is connected to the first optical isolator and then connected to port 2 of the first wave combiner; port 3 of the first wave splitter is connected to port 1 of the first circulator, port 2 of the first circulator is connected to port 3 of the first wave combiner, and port 1 of the first wave combiner is connected to the first sensing optical fiber; port 1 of the Nth wave splitter is connected to port 1 of the (N-1)th wave combiner through the (N-1)th sensing optical fiber, port 2 is connected to the Nth optical isolator and then connected to port 2 of the Nth wave combiner, port 3 is connected to port 1 of the Nth circulator, port 2 of the Nth circulator is connected to port 3 of the Nth wave combiner, and the Nth circulator is connected to the Nth sensing optical fiber; ports 3 of each circulator are connected to the phase demodulation module through their respective detection optical fibers.

[0042] The working principle of the multi-channel telemetry optical fiber sensing system using a series circulator structure is as follows:

[0043] Step 1, mixed light transmission:

[0044] a. The mixed light of the pulse signal light and the Raman pump light emitted by the pulse light source system is separated by the first wave splitter, wherein the Raman pump light is output from port 2, transmitted to port 2 of the first combiner through the first optical isolator, and then mixed with the pulse light signal output from port 3, entering through port 1 of the first circulator, and entering port 3 of the first combiner after being output from port 2; the mixed light is transmitted in the first sensing optical fiber, and Rayleigh scattered light signal is generated during the transmission process, and is output through ports 2 and 3 of the first combiner in the reverse direction of the transmission direction of the pulse light signal, wherein the Rayleigh scattered light signal coming out of port 2 is blocked by the optical isolator and cannot be transmitted further, and the Rayleigh scattered light signal coming out of port 3 enters through port 2 of the first circulator, is output from port 3, and enters the phase demodulation module through the first detection optical fiber;

[0045] b. Since the first sensing optical fiber is connected to the wave splitter of the second structural unit, the mixed light in the first sensing optical fiber continues to be transmitted forward and is separated by the second wave splitter, wherein the Raman pump light is output from port 2, transmitted to port 2 of the second combiner via the second optical isolator, and then mixed with the pulse light signal output from port 3, entering through port 1 of the second circulator, and entering port 3 of the second combiner after being output from port 2; it is transmitted in the second sensing optical fiber, and a Rayleigh scattered light signal is generated during the transmission process, which is output through ports 2 and 3 of the second combiner in the reverse direction of the transmission direction of the pulse light signal, wherein the Rayleigh scattered light signal coming out of port 2 is blocked by the optical isolator and cannot be transmitted further, and the Rayleigh scattered light signal coming out of port 3 enters through port 2 of the second circulator, is output from port 3, and enters the phase demodulation module via the second sensing optical fiber;

[0046] c. The above transmission process is extended to the Nth structural unit, thereby realizing the detection of long-distance optical pulse signals under high repetition frequency;

[0047] Step 2, pulse signal processing: After receiving the complete Rayleigh scattering signal, the phase demodulation module performs splicing processing to restore the vibration conditions within the entire detection range.

[0048] Example 3

[0049] This embodiment provides a multi-channel telemetry optical fiber sensing system, when N circulators are arranged in a parallel structure: it also includes a splitter; the 1' port of the splitter is connected to the pulse light source system as an input port, and the splitter also has N ports as output ports, and each is connected to the 1 port of a corresponding circulator, the 2 port of the circulator is connected to the sensing optical fiber, and the 3 port is connected to the phase demodulation module through the Nth detection optical fiber. In addition, it also includes N optical fiber amplifiers and N delay optical fibers; the 1 port of the Nth circulator is connected to the Nth output port of the splitter through the Nth optical fiber amplifier and the Nth delay optical fiber in sequence.

[0050] The working principle of the multi-channel telemetry optical fiber sensing system using a parallel circulator structure is as follows:

[0051] Step 1, mixed light transmission:

[0052] a. The mixed light of the pulse signal light and the fully pumped light emitted by the pulse light source system is divided into N paths by a splitter. The first mixed light is output from port 1 of the splitter, transmitted in the first delay optical fiber, passes through the first optical fiber amplifier, enters from port 1 of the first circulator, outputs from port 2, and is transmitted in the first sensing optical fiber. Rayleigh scattered light signals are generated during the transmission process, enter through port 2 of the first circulator in the reverse direction of the transmission direction of the pulse light signal, output from port 3, and enter the phase demodulation module through the first detection optical fiber;

[0053] b. The second mixed light is output from port 2 of the splitter, transmitted in the second delay fiber, passes through the second EDFA, enters from port 1 of the second circulator, outputs from port 2, and is transmitted in the second sensing fiber. During the transmission, a Rayleigh scattered light signal is generated, which enters from port 2 of the second circulator in the reverse direction of the transmission direction of the pulse light signal, outputs from port 3, and enters the phase demodulation module through the second detection fiber.

[0054] c. The above transmission process is extended to the Nth circulator, thereby realizing the detection of long-distance optical pulse signals at a high repetition frequency;

[0055] Step 2, pulse signal processing: After receiving the complete Rayleigh scattering signal, the phase demodulation module performs splicing processing to restore the vibration conditions within the entire detection range.

[0056] After the pulse light source system generates the first pulse light signal, a back-scattered Rayleigh light signal is generated in the first sensing fiber in chronological order, and then a back-scattered Rayleigh light signal is generated in the second sensing fiber... and so on, a back-scattered Rayleigh light signal is generated in the Nth sensing fiber. Compared with the back-scattered Rayleigh light signal generated in the N-1th sensing fiber, the back-scattered Rayleigh light signal generated in the Nth sensing fiber enters the phase demodulation module later than the former, so the back-scattered Rayleigh light signals of the two adjacent circulators will not overlap in time. Finally, when the entire section of optical fiber is divided into N sections, the repetition frequency of the original limit light pulse signal can be increased by N times, thereby increasing the upper limit of the detection phase change signal by N times.

[0057] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-channel telemetry optical fiber sensing system, comprising a pulse light source system and a phase demodulation module, wherein the pulse light source system and the phase demodulation module are connected via an optical cable communication, characterized in that: Also includes N circulators, N is a positive integer ≥ 2; N circulators are arranged in sequence along the transmission direction of the optical cable; wherein along the overall transmission direction of the optical cable, the lengths of the sensing optical fibers between two adjacent circulators are equal; each circulator is connected to the phase demodulation module via an independent detection optical fiber; the difference between the length of the detection optical fiber used to connect the Nth circulator and the phase demodulation module and the length of the detection optical fiber used to connect the N-1th circulator and the phase demodulation module is equal; When N circulators are arranged in a series structure: they also include N wave splitters, N optical isolators and N combiners; one wave splitter, one circulator, one optical isolator and one combiner are used as one structural unit, with a total of N structural units; along the transmission direction, in each structural unit, the wave splitter is located at the upstream end, the combiner is located at the downstream end, and the circulator optical isolator is connected in parallel between the wave splitter and the combiner; the N structural units are connected in series in sequence through the sensing optical fiber along the transmission direction, the wave splitter of the first structural unit is connected to the pulse light source system, and the wave splitter of the Nth structural unit is connected to the combiner of the N-1th structural unit through the sensing optical fiber; wherein the 1st port of the 1st wave splitter is connected to the pulse light source system, and the 2nd port is connected to the After the 1st optical isolator, it is connected to the 2nd port of the 1st combiner; the 3rd port of the 1st splitter is connected to the 1st port of the 1st circulator, the 2nd port of the 1st circulator is connected to the 3rd port of the 1st combiner, and the 1st port of the 1st combiner is connected to the first sensing optical fiber; the 1st port of the Nth splitter is connected to the 1st port of the N-1th combiner through the N-1th sensing optical fiber, the 2nd port is connected to the 2nd port of the Nth combiner after being connected to the Nth optical isolator, the 3rd port is connected to the 1st port of the Nth circulator, the 2nd port of the Nth circulator is connected to the 3rd port of the Nth combiner, and the Nth circulator is connected to the Nth sensing optical fiber; the 3rd ports of each circulator are connected to the phase demodulation module through their respective detection optical fibers; For each circulator, end 1 of the circulator is used to input the pulse light signal, and end 2 of each circulator is connected to the sensing optical fiber. During the transmission of the pulse light signal through the sensing optical fiber, a Rayleigh scattered light signal is generated, which enters through port 2 of the circulator in the reverse direction of the transmission direction of the pulse light signal and is output from port 3. Finally, it enters the phase demodulation module through the detection optical fiber. In addition, only one pulse light can exist at the same time in the same section of sensing optical fiber.

2. A multi-channel telemetry optical fiber sensing system according to claim 1, characterized in that: In the overall transmission direction of the optical cable, the distances between any two adjacent circulators are equal.

3. A multi-channel telemetry optical fiber sensing method, characterized in that: A multi-channel telemetry optical fiber sensing system according to claim 1 is used; the transmission process comprises the following steps: Step 1, mixed light transmission: a. The mixed light of the pulse signal light and the Raman pump light emitted by the pulse light source system is separated by the first wave splitter, wherein the Raman pump light is output from port 2, transmitted to port 2 of the first combiner through the first optical isolator, and then mixed with the pulse light signal output from port 3, entering through port 1 of the first circulator, and then output from port 2 and entering port 3 of the first combiner; Transmitted in the first sensing optical fiber, Rayleigh scattered light signal is generated during the transmission process, and is output through port 2 and port 3 of the first combiner in the reverse direction of the pulse optical signal transmission direction, wherein the Rayleigh scattered light signal coming out of port 2 is blocked by the optical isolator and cannot be transmitted further, and the Rayleigh scattered light signal coming out of port 3 enters through port 2 of the first circulator, is output from port 3, and enters the phase demodulation module through the first detection optical fiber; b. Since the first sensing optical fiber is connected to the wave splitter of the second structural unit, the mixed light in the first sensing optical fiber continues to be transmitted forward and is separated by the second wave splitter, wherein the Raman pump light is output from port 2 and transmitted to port 2 of the second combiner via the second optical isolator, and then mixed with the pulse light signal output from port 3, entering via port 1 of the second circulator, and entering port 3 of the second combiner after being output from port 2; it is transmitted in the second sensing optical fiber, and a Rayleigh scattered light signal is generated during the transmission process, which is output through ports 2 and 3 of the second combiner in the reverse direction of the transmission direction of the pulse light signal, wherein the Rayleigh scattered light signal coming out of port 2 is blocked by the optical isolator and cannot be transmitted further, and the Rayleigh scattered light signal coming out of port 3 enters through port 2 of the second circulator, is output from port 3, and enters the phase demodulation module via the second sensing optical fiber; c. The above transmission process is extended to the Nth structural unit, thereby realizing the detection of long-distance optical pulse signals under high repetition frequency; Step 2, pulse signal processing: After receiving the complete Rayleigh scattering signal, the phase demodulation module performs splicing processing to restore the vibration conditions within the entire detection range.

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