Device for avoiding coherent fading in DVS system
By using 1xN optical switches and delay fibers of different lengths in the DVS system, the problem of inaccurate positioning of optical cable vibration was solved, and a more efficient positioning effect was achieved.
Patent Information
- Application Number
- CN202520231557.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-13
- Publication Date
- 2026-01-02
- Estimated Expiration
- 2035-02-13
AI Technical Summary
When the DVS system locates the vibration position of the optical cable, the signal strength is weakened due to coherent fading, resulting in inaccurate positioning or no response.
By employing two 1xN optical switches and N delay fibers of varying lengths, coherent fading is avoided and signal stability is ensured by changing the optical path length.
It improves the accuracy and efficiency of locating the vibration position of optical cables and avoids the effects of coherent fading.
Smart Images
Figure CN223756153U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of optical fiber sensing technology, in particular to a device for avoiding coherent fading in DVS system. BACKGROUND
[0002] With the development of society and the progress of science and technology, optical fiber sensing technology has been very widely used in various fields of society. DVS system is an application based on optical fiber sensing technology, mainly applied to positioning the vibration position of optical cable.
[0003] By knocking the optical cable, the DVS system can quickly locate the vibration position of the target optical cable. This positioning not only has no loss to the optical cable, but also has high efficiency and accuracy. However, due to the randomness of the phase change, polarization state change and Rayleigh scattering of the optical signal in the optical cable, the positioning effect of the target optical cable at some positions may vary at different times or conditions when the DVS system measures the target optical cable. The weakening of the detection signal caused by the phase fluctuation of the interference field is called coherent fading. Coherent fading can cause the vibration signal of the same position of the target optical cable to change greatly with time or even no response, or the vibration signal of different positions of the target optical cable to be greatly different at the same time under the same vibration condition or even no response. SUMMARY
[0004] The utility model aims at providing a device for avoiding coherent fading in DVS system, which can avoid the influence of coherent fading on DVS system and improve the positioning accuracy and efficiency of the vibration position of the target optical cable.
[0005] To achieve the above-mentioned purpose, the utility model provides the following scheme:
[0006] A device for avoiding coherent fading in DVS system, comprising: two 1xN optical switches and N delay optical fibers, N≥2; one end of the com of one of the 1xN optical switches is connected with the output end of the DVS system, and the com of the other 1xN optical switch is connected with the target optical cable to be measured; each of the delay optical fibers is arranged between the two 1xN optical switches, and the two ends of each of the delay optical fibers are connected with the corresponding 1xN optical switch.
[0007] Optionally, the lengths of the delay optical fibers are different and do not repeat periodically.
[0008] Optionally, the length difference of every two delay optical fibers is greater than the maximum resolution of the DVS system.
[0009] Optionally, the number of the delay optical fibers is 8.
[0010] Optionally, the lengths of the delay optical fibers are respectively set as 25m, 33m, 51m, 87m, 102m, 233m, 527m and 1005m.
[0011] According to the specific embodiments provided by the utility model, the utility model discloses the following technical effects:
[0012] The utility model discloses a device that avoids coherent fading in DVS system, the device includes two 1xN path optical switch and N delay optical fiber, N >= 2, wherein the com of one 1xN path optical switch is connected with the output end of DVS system, and the com of another 1xN path optical switch is connected with the target cable to be measured, each delay optical fiber is arranged between two 1xN path optical switch, and the both ends of each delay optical fiber are connected with the 1xN path optical switch of corresponding position respectively. When DVS is in the vibration position of positioning target cable, due to coherent fading, there can be the condition that the vibration signal difference of the same position of target cable is large with time change even no reaction, or there can be the condition that the vibration signal difference of different positions of target cable is large even no reaction under the same vibration condition at the same time, therefore, the utility model discloses a device for signal measurement, can avoid the influence of DVS system to coherent fading, and more accurately and more efficiently locates the vibration position of target cable. BRIEF DESCRIPTION OF DRAWINGS
[0013] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or prior art, the following will briefly introduce the drawings needed to be used in the embodiments, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without paying creative labor.
[0014] Figure 1 It is the device structure schematic diagram of the utility model to avoid coherent fading in DVS system.
[0015] Reference signs:
[0016] 1, DVS system, 2, 1xN path optical switch, 3, delay optical fiber, 4, target cable. DETAILED DESCRIPTION
[0017] Clearly, the described embodiments are merely a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments in the present utility model, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present utility model.
[0018] The utility model discloses a kind of devices for avoiding coherent fading in DVS system, can avoid the influence of DVS system by coherent fading, improve the positioning accuracy and positioning efficiency of target cable vibration position.
[0019] In order to make the above-mentioned purposes, features and advantages of the present utility model more apparent and easy to understand, the present utility model will be further described in detail below with reference to the drawings and specific embodiments.
[0020] As shown in Figure 1 The utility model discloses a kind of devices for avoiding coherent fading in DVS system 1, comprising: two 1xN optical switch 2 and N delay optical fiber 3, N≥2;One of the described 1xN optical switch 2 is connected with the output end of DVS system 1, and the com end of another 1xN optical switch 2 is connected with the target cable 4 to be measured;Each of the described delay optical fiber 3 is arranged between two 1xN optical switch 2, and the two ends of each of the described delay optical fiber 3 are connected with the 1xN optical switch 2 of corresponding position respectively.
[0021] As a specific embodiment, the length of the delay optical fiber 3 is different, and should be random as much as possible to avoid periodic interference, and the minimum value of the length of the delay optical fiber 3 depends on the linewidth of the DVS system 1 laser, and the minimum difference between the lengths of the delay optical fiber 3 should be greater than the maximum resolution of the DVS system 1.
[0022] When the length of the optical fiber changes, the phase relationship of the return light of different scattering points will change, and the optical switch changes the total optical path of the system by accessing different length of extension optical fiber, so that the original coherent fading points are redistributed, thereby avoiding the situation that some point signals are always weak.
[0023] In the present embodiment, the 1xN optical switch 2 is set to 1x8 optical switch, the number of delay optical fiber 3 is 8, and the lengths are 25m, 33m, 51m, 87m, 102m, 233m, 527m and 1005m respectively, corresponding to 1-8 channels of the 1xN optical switch 2.
[0024] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts of each embodiment can be referred to each other.
[0025] The principles and implementation modes of the present application are described herein by using specific examples, and the above examples are only used to help understand the core idea of the present application. Meanwhile, for those skilled in the art, the specific implementation modes and application ranges will be changed according to the idea of the present application. In conclusion, the content of the present specification should not be understood as a limitation of the present application.
Claims
1. An apparatus for avoiding coherent fading in a DVS system, the apparatus comprising: The application relates to a device for testing a target optical cable, comprising: two 1xN optical switches and N delay optical fibers, N>=2; wherein the com end of one of the 1xN optical switches is connected with the output end of a DVS system, the com end of the other 1xN optical switch is connected with the target optical cable to be tested; each of the delay optical fibers is arranged between the two 1xN optical switches, and the two ends of each of the delay optical fibers are connected with the 1xN optical switches at corresponding positions.
2. The apparatus for avoiding coherent fading in a DVS system of claim 1, wherein, The lengths of the delay optical fibers are different and do not repeat periodically.
3. The apparatus for avoiding coherent fading in a DVS system of claim 1, wherein, The length difference between every two of the delay optical fibers is greater than the maximum resolution of the DVS system.
4. The apparatus for avoiding coherent fading in a DVS system of claim 1, wherein, The number of the delay optical fibers is set to be 8.
5. The apparatus for avoiding coherent fading in a DVS system according to claim 4, wherein, The lengths of the delay optical fibers are respectively set to be 25m, 33m, 51m, 87m, 102m, 233m, 527m and 1005m.