CN109373909A - High-precision optical fiber length measuring system and measurement method - Google Patents
High-precision optical fiber length measuring system and measurement method Download PDFInfo
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- CN109373909A CN109373909A CN201811438415.1A CN201811438415A CN109373909A CN 109373909 A CN109373909 A CN 109373909A CN 201811438415 A CN201811438415 A CN 201811438415A CN 109373909 A CN109373909 A CN 109373909A
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- optical fiber
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- vector network
- radio frequency
- network analyzer
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
Abstract
The invention discloses a kind of high-precision optical fiber length measuring system and using the measurement method of measuring system measurement fiber lengths, the measuring system includes radio signal transmission link and vector network analyzer, and the radio signal transmission link is mainly made of radio frequency electrooptic switching element, test optical fiber and radio frequency photoelectric conversion unit.In the radio signal transmission link, the radiofrequency signal that vector network analyzer issues first is modulated into optical signal by electrooptic switching element, optical fiber is transferred to photoelectric conversion unit to optical signal after tested, then the unit that is photoelectrically converted is demodulated into radiofrequency signal, returns to vector network analyzer.The measurement method is to be sent in the identical radiofrequency signal of different frequency point phase by measuring vector network analyzer, in the delay time of transmission link, to measure the length of optical fiber.Of the invention a kind of high-accuracy optical fiber length measuring system and measurement method have high-precision, the distinguishing feature of remote range, high stability.
Description
Technical field
The present invention relates to technical field of optical fiber measurement more particularly to a kind of high-precision optical fiber length measuring system and adopt
With the measurement method of measuring system measurement fiber lengths.
Background technique
Into after 21 century, fiber optic communication has become the hot spot of industry with 5G cooperative development, and optical fiber is transmitted across in signal
Have many advantages, such as high anti-jamming capacity, high transfer rate and extremely low transmission error rates in journey, therefore optical fiber is communicated as 5G
The best medium of network traffic, fiber optic communication also become the best-of-breed technology selection of wide-band communication system.It is real in each type optical fiber
Test and engineer application in, be often related to the measurement of fiber lengths, the delay of the length major influence on signal of optical fiber and letter
Number phase, delay will affect sampling time, Distance positioning of many communication systems etc., the phase of signal mainly influences communication system
System and acquisition, the scanning beam of optical fiber sensing system data etc..The spread speed of theoretical glazing in a fiber is 2 × 108m/s,
Fiber lengths difference 1mm can be calculated, delay time just differs 0.005ns, signal phase difference=optical fiber variation length/light
Spread speed (speed/refractive index of light in a vacuum) × signal frequency × 360 ° in a fiber, so in the frequency of 1GHz
Under, optical fiber length difference 1mm, phase difference=1 × 10-3/ (2 × 108) × 1 × 109 × 360 °=1.8 °, and general entire communication
Phase difference between system and the road optical fiber sensing system Zhong Ge signal is also just at 5 ° or so.It can be said that accurately fiber lengths are surveyed
It measures all particularly important in almost all of fiber optic communication and optical fiber sensing system.
The common measurement method of fiber lengths has following two:
(1) optical time domain reflectometer OTDR:OTDR be just widely applied to the fiber optic network communications field measure fiber lengths,
Detect optical cable breakpoint location etc..It is made according to back rayleigh scattering and Fresnel reflection theory, and measuring accuracy can achieve
The magnitude of rice, test scope reach as high as kilometers up to a hundred.But since volume is relatively large for OTDR equipment, to a certain extent
It limits its application.
(2) probe beam deflation measuring instrument OFDR:OFDR is to carry out frequency modulation(PFM) using to light source, and the signal on detector is clapped
Frequency can increase with the increase of scattering point distance, and the energy on detector is proportional to the point scattering size.The measurement essence of OFDR
Degree can achieve millimeter magnitude than OTDR high, and measurement range is up to several kms, practicability with higher, but OFDR system
Requirement to laser light source is very high, so measurement stability is poor.
Obviously, no matter using which kind of above measurement method, the height in reality to optical fiber length measuring cannot all be met simultaneously
The requirement of precision, remote range, high stability.
Summary of the invention
To overcome the shortcomings of in background technique, the invention discloses a kind of high-precision optical fiber length measuring system and measurement sides
Method.
For achieving the above object, the present invention adopts the following technical scheme:
A kind of high-accuracy optical fiber length measuring system, including radio signal transmission link and vector network analyzer, it is described
Radio signal transmission link is mainly made of radio frequency electrooptic switching element, test optical fiber and radio frequency photoelectric conversion unit；The arrow
It measures Network Analyzer signal output end and sends radiofrequency signal to radio frequency electrooptic switching element；The radio frequency electrooptic switching element will be penetrated
Frequency signal is converted into optical signal, and passes through test optical fiber transmission；The radio frequency photoelectric conversion unit is transmitted optical fiber is tested
Optical signal be converted into radiofrequency signal, and return to the receiving end of vector network analyzer；The vector network analyzer is to penetrating
The radiofrequency signal that frequency electrooptic switching element is sent is identical in the phase of different frequency point.
A kind of high-accuracy optical fibre length measurement method, includes the following steps:
Step 1: vector network analyzer signal output end is sent in different frequency point phase to radio frequency electrooptic switching element
Rf-signal modulation is transferred to and is penetrated at optical signal, and by testing optical fiber by identical radiofrequency signal, radio frequency electrooptic switching element
Optical signal demodulation after radiofrequency signal, is returned again to vector network analyzer by frequency photoelectric conversion unit, radio frequency photoelectric conversion unit
Signal receiving end；
Step 2: vector network analyzer is transferred to phase test shelves, in the frequency bandwidth of vector network analyzer setting
It is interior, the numerical value of electricity delay is adjusted, approaching the slope for the phase for receiving signal is 0, and electricity delay numerical value at this moment is radio frequency letter
Number transmission link delay value T1；
Step 3: system optical fiber joined in transmission link due to the communication for being used for each unit in test macro, therefore,
After removing test optical fiber, the system fiber delay time value T0 of primary system itself is measured again, the delay value is in fixed system
For fixed value；
Step 4: the delay value T1 of the transmission link obtained with step 2 subtracts system fiber delay time value T0, as light exists
Test the time T of optical fiber transmission；
Step 5: the spread speed of light in a fiber is the speed C of light in a vacuum and the folding of light in a fiber under room temperature
The ratio of rate N is penetrated, so the length L=C*T/N of measurement optical fiber.
Due to the adoption of the technical scheme as described above, the invention has the following beneficial effects:
(1) high-precision.The present invention is the high-precision phase position (essence using radio signal transmission technology and vector network analyzer
Degree is up to 0.0001 °) and high-precision delay (precision is up to 0.0001ns) characteristic, make the precision of fiber lengths (packet within 1mm
Runout error containing instrument).
(2) remote range.Optical fiber measurement distance of the invention is up to hundreds of kilometer.
(3) high stability.Measurement process of the present invention considers environmental factor, optical fiber material etc. completely, and measurement result is stablized
Property and consistency are high, and error change is within 0.1mm.
A kind of high-precision optical fiber length measuring technique of the invention has the significant spy of high-precision, remote range, high stability
Point, reaches the international leading level, and solves at this stage that optical fiber length measuring technology Instrumental equipment volume is huge, use condition is severe
It carves, the problems such as measurement accuracy is insufficient, stability is poor, substantially increases the precision of phase sample, Distance positioning.
Detailed description of the invention
Fig. 1 is optical fiber length measuring basic schematic diagram of the invention.
Fig. 2 is radio signal transmission link schematic diagram.
Fig. 3 is radiofrequency signal shift theory figure.
Fig. 4 is the amplitude-frequency characteristic figure that vector network analyzer issues signal.
Fig. 5 is the amplitude-frequency characteristic figure that vector network analyzer receives signal.
Fig. 6 is that measurement optical fiber link delay T1 measures block diagram.
Fig. 7 is that system optical fiber link delay T0 measures block diagram.
In figure: 1, the optical signal that radiofrequency signal is converted into；2, the optical signal that laser direct current supply generates.
Specific embodiment
By the following examples, in conjunction with attached drawing can the detailed explanation present invention, the open purpose of the present invention is intended to protect
Protect all technological improvements in the scope of the invention.
The present invention is to be sent in the identical radiofrequency signal of different frequency point phase by measuring vector network analyzer, is being passed
The delay time of transmission link, to measure the length of optical fiber.The radiofrequency signal is in transmission link, first by electrooptic switching element
It is modulated into optical signal, optical fiber is transferred to photoelectric conversion unit to optical signal after tested, then the unit that is photoelectrically converted is demodulated into radio frequency letter
Number, return to vector network analyzer.
Vector network analyzer is transferred to phase test shelves, in the frequency bandwidth of vector network analyzer setting, is adjusted
The numerical value of electricity delay makes the slope for the phase for receiving signal approach the compensation rate for increasing or reducing electricity delay for 0, phase it is oblique
Rate can all become larger.At this moment electricity delay numerical value is delay value T1 of the radiofrequency signal in transmission link.Due to being used in test macro
In the communication of each unit, system optical fiber joined in transmission link, therefore, the system optical fiber that measure primary system itself again prolongs
Duration T0, the delay value T1 of transmission link subtract system fiber delay time value T0, as light test optical fiber transmission time T, then
By calculating formula of length L=C*T/N, the length of measurement optical fiber is calculated.
Such as: under room temperature, in G652.D optical fiber, the refractive index N of the light of 1310nm is the light of 1.4675,1310nm wavelength
The T that is delayed in the optical fiber of G652.D is 1us, then length L=C*T/N=1 × 10 of the optical fiber-6×2.99792458×108/
1.4675=204.287876 rice.
Part not in the detailed description of the invention is the prior art.
Claims (2)
1. a kind of high-accuracy optical fiber length measuring system, it is characterised in that: including radio signal transmission link and vector network point
Analyzer, the radio signal transmission link is mainly by radio frequency electrooptic switching element, test optical fiber and radio frequency photoelectric conversion unit group
At；The vector network analyzer signal output end sends radiofrequency signal to radio frequency electrooptic switching element；The radio frequency electric light turns
It changes unit and radiofrequency signal is converted into optical signal, and pass through test optical fiber transmission；The radio frequency photoelectric conversion unit is by test light
The optical signal that fibre transmits is converted into radiofrequency signal, and returns to the receiving end of vector network analyzer；The vector network
The radiofrequency signal that analyzer is sent to radio frequency electrooptic switching element is identical in the phase of different frequency point.
2. a kind of high-accuracy optical fibre length measurement method as described in claim 1, which comprises the steps of:
Step 1: to radio frequency electrooptic switching element to be sent in different frequency point phase identical for vector network analyzer signal output end
Radiofrequency signal, radio frequency electrooptic switching element by rf-signal modulation at optical signal, and by test optical fiber be transferred to radio frequency light
Optical signal demodulation after radiofrequency signal, is returned again to vector network analyzer signal by electric converting unit, radio frequency photoelectric conversion unit
Receiving end；
Step 2: vector network analyzer is transferred to phase test shelves, in the frequency bandwidth of vector network analyzer setting, adjust
Economize on electricity the numerical value being delayed, and approaching the slope for the phase for receiving signal is 0, and electricity delay numerical value at this moment is that radiofrequency signal is passing
The delay value T1 of transmission link；
Step 3: joined system optical fiber due to the communication for being used for each unit in test macro in transmission link, therefore, removing
After testing optical fiber, the system fiber delay time value T0 of primary system itself is measured again, which is solid in fixed system
Definite value；
Step 4: the delay value T1 of the transmission link obtained with step 2 subtracts system fiber delay time value T0, as light is being tested
The time T of optical fiber transmission；
Step 5: the spread speed of light in a fiber is the speed C of light in a vacuum and the refractive index of light in a fiber under room temperature
The ratio of N, so the length L=C*T/N of measurement optical fiber.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109873286A (en) * | 2019-02-27 | 2019-06-11 | 陈颖 | A kind of radio-frequency cable component phase equalization assembly method |
| CN111064507A (en) * | 2019-12-25 | 2020-04-24 | 中国联合网络通信集团有限公司 | Method and device for detecting length of optical fiber link and terminal equipment |
| CN113295097A (en) * | 2021-05-25 | 2021-08-24 | 中国电子科技集团公司第四十一研究所 | Optical fiber length measuring method and device based on group delay of optical wave element analyzer |
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|---|---|---|---|---|
| CN109873286A (en) * | 2019-02-27 | 2019-06-11 | 陈颖 | A kind of radio-frequency cable component phase equalization assembly method |
| CN111064507A (en) * | 2019-12-25 | 2020-04-24 | 中国联合网络通信集团有限公司 | Method and device for detecting length of optical fiber link and terminal equipment |
| CN113295097A (en) * | 2021-05-25 | 2021-08-24 | 中国电子科技集团公司第四十一研究所 | Optical fiber length measuring method and device based on group delay of optical wave element analyzer |
| CN113295097B (en) * | 2021-05-25 | 2022-10-28 | 中国电子科技集团公司第四十一研究所 | Optical fiber length measuring method and device based on optical wave element analyzer group delay |
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