CN1275397C - Optical signal transmission delay measuring method in transmission chain and apparatus thereof - Google Patents
Optical signal transmission delay measuring method in transmission chain and apparatus thereof Download PDFInfo
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- CN1275397C CN1275397C CNB031501168A CN03150116A CN1275397C CN 1275397 C CN1275397 C CN 1275397C CN B031501168 A CNB031501168 A CN B031501168A CN 03150116 A CN03150116 A CN 03150116A CN 1275397 C CN1275397 C CN 1275397C
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Abstract
The present invention relates to a method and a device thereof for measuring the transmission delay of optical signals in transmission links, which belongs to the technical field of optoelectronics and optical fiber communication. The method comprises the procedures: optical fibers to be measured are connected with a measuring system to be annular, and DC optical signals are injected into transmission optical fibers to be measured; the power of the returned DC optical signals is adjusted to match with that of the injected DC optical signals; optical detection signals with certain length and period are re-injected into the transmission optical fibers to be measured so as to transmit the optical detection signals in the cyclic loop of the optical fibers to be measured; the transmission delay of the optical signals in the loop is judged according to the periodical power change, detected by a receiving terminal, of the optical detection signals, and the results are obtained. The present invention which can avoid the complicated segmental measurement and the system error in the prior art has the characteristics of simple method and low device cost, and is especially suitable for measuring the signal transmission delay in an actual optical fiber link which is already laid and composed of multistage optical fibers, an optical amplifier and other network devices.
Description
Technical field the invention belongs to photoelectron technology and technical field of optical fiber communication.Be particularly related to the method for measurement and the device of light signal transmission delay in transmission link
The develop rapidly of background technology Fiber Optical Communication System makes and makes up the expensive in astronomical figure of a jumbo Fiber Optical Communication System of long distance that this giant-scale engineering must be through strict experimental demonstration before project verification.Meanwhile, modern communication systems is more and more harsher to the requirement of sequential, and minimum time error may cause system to go wrong.Such as in the EPON based on Ethernet, signal must accurately be measured to the transmission delay of optical network unit (ONU) in Optical Network Terminal (OLT), otherwise network can't operate as normal.In addition, adopt optical fiber link to do in the sensing and controlling system of transmission medium at some, accurately know the time that sensor events takes place when needs, the transmission delay of signal in optical fiber link also needs to be measured to reduce systematic error.Therefore, the transmission delay of measuring light signal in transmission link is unusual important techniques.
Measuring light signal technology of transmission delay in transmission link of comparative maturity is that optical time domain reflection is measured (OTDR) technical method at present.The display mode of OTDR is similar to the display mode of the electric TDR that is used for determining the coaxial cable defective locations.In optical fiber, exist the bias light of a reverberation and leak light to let out, it appears in the demonstration of OTDR with the form of baseline slope (baseline slope).The discontinuous point of the Light negative of optical fiber will produce discrete reflection, and these discrete reverberation will appear in the demonstration of OTDR as a row pulse, and the position of these pulses is then corresponding to the position of discontinuous point.
Adopt the general structure of optical time domain reflectometer of said method and annexation as shown in Figure 1, its structure mainly comprises light source, pulse modulator, circulator, photodetector, optical system, pulse generation and data processing section.Its operation principle is: at first make light source produce the burst pulse light wave with light source of pulse generator modulation, be coupled into optical fiber through optical system.Reflection can appear in light wave when transmitting in optical fiber, have discrete reflection signal power sudden change in the joint.Reverberation returns along optical fiber, passage in transit fiber optical circulator input photoelectric detector, become the signal of telecommunication through photoelectric detector, because the position that reverberation reflects in optical fiber is different, so its time that arrives photoelectric detector is also different, therefore can obtain light signal is brought in transmission back from optical fiber one time delays from catoptrical power time waveform.Wherein the reason that data are handled is, back-scattering light is very faint, is submerged in a slice noise, therefore, use Sampling Integral device integration, at certain time intervals to faint scattered signal sampling and summation.
Also have an ADC (analog to digital converter) fast in that some OTDR is inner, it can be with the waveform digitization of the pulse that reflects.Some OTDR has then adopted a plurality of ADC, so that carry out time interleaving conversion, this conversion that ADC carried out of using in the general digital oscilloscope (DSO) of quick sampling.Time interleaving conversion will increase the sampling rate of instrument, and in the set limit of instrument bandwidth, sampling rate is high more, and instrument is determined from the precision of the signal delay of optical fiber discontinuous point position reflection also just high more.
Measure for light signal transmission delay in transmission link, this method has a bigger shortcoming, and the OTDR technology is in single port measuring optical fiber length, its detectable signal need be in same transmission link transmitted in both directions.Therefore it is difficult to be applied on the optical fiber link of amplifier, and the link that especially has one-way transmission character such as isolator more can not be measured with the OTDR technology.And the transmission link of forming optical fiber loop now is generally all very complicated, and signal through the multi-stage fiber transmission, amplifies in loop, filtering or the like, even the conversion of photoelectricity light, and wherein a lot of devices all have the character of one-way transmission.Utilize the OTDR technology can only sectionalization test light signal transmission delay in bi-directional transmission link (mainly being optical fiber), so not only complicated operation be loaded down with trivial details, and it is also influential to measurement result to have ignored the time-delay of other devices.In addition, because the OTDR technology adopts initiatively and measures, need own to transmitting and detecting the signal that obtains and carry out accurate timing, this method relies on very big to the timing system of its device, its certainty of measurement is subjected to the restriction of its circuit response speed, therefore the high OTDR time-domain reflectomer of precision costs an arm and a leg at present, such as the Aglent 8147 of Agilent company.
Summary of the invention the objective of the invention is can not directly measure the total transmission delay problem of optic communication links of one-way transmission for solving prior art.A kind of light signal transmission delay measurement method and device in transmission link are proposed, utilizing actual fiber transmission link all is the situation that adopts bi-directional symmetrical to lay basically, can avoid the loaded down with trivial details and systematic error of prior art areal survey, have the advantages that method is simple, installation cost is low, especially adapt to laid by multi-stage fiber, the measurement of signal transmission delay in the actual fiber link that image intensifer and other network devices are formed.
A kind of light signal transmission delay measurement method in transmission link that the present invention proposes is characterized in that, tested optical fiber and measuring system are connected into ring-type; May further comprise the steps:
1) gives straightening time signal to tested Transmission Fibers injection;
2) adjust the direct current optical signal power that returns through Transmission Fibers, make the direct current optical signal power that returns and inject direct current optical signal power coupling;
3) in tested Transmission Fibers, inject the sensed light signal of certain-length, some cycles again, this sensed light signal is transmitted in the tested optical fiber looped cycle;
4) detect the cyclic variation of this sensed light signal power according to receiving terminal, judge the transmission delay of light signal in loop;
(1) when detected optical signal power waveform has periodicity not have the depression of light signal, then inject the light signal time and delay time less than tested Transmission Fibers, therefore tested Transmission Fibers transmission delay is detected optical signal power wave period;
(2) when detected optical signal power waveform is straight line, then injects the light signal time and delay time identical with tested Transmission Fibers.
Light signal transmission delay measurement mechanism in transmission link of the employing said method that the present invention proposes is characterized in that, comprises the LASER Light Source that is used for injecting to tested Transmission Fibers light signal; Be used to adjust the power-adjustable attenuator of optical signal power; Be used for the light signal of this light source is modulated into first optical switch and second optical switch of periodic signal; Be used to control the loop control unit of this optical switch time, light signal injected the optical coupler of tested Transmission Fibers; And the data processing equipment that light signal is handled; Its connecting relation is: the output of this LASER Light Source output, power-adjustable attenuator links to each other with the input of optical coupler by first optical switch, second optical switch respectively, an output of optical coupler links to each other with data processing equipment, another output of optical coupler is the output of this measurement mechanism, and the input of power-adjustable attenuator is the input of this measurement mechanism.
Characteristics of the present invention and good result
The inventive method can be measured the optical fiber link transmission delay of whole one-way transmission simply and easily, and it is very high that its certainty of measurement can reach.The raising of certainty of measurement only depends on the response speed of receiving terminal photo-detector and the resolution of sampling oscilloscope, has reduced certainty of measurement to controller, and the requirement of response device times such as optical switch has reduced the realization cost.The present invention does as a whole the measurement to signal in the fiber transmission link transmission time, has reduced workload and the fussy degree measured, has improved efficiency of measurement.
Description of drawings:
Fig. 1 is existing OTDR optical time domain reflectometer structural representation.
Fig. 2 forms structured flowchart for device embodiment of the present invention.
Fig. 3 is a present embodiment optical switch operating principle schematic diagram.
Fig. 4 is a method of measurement FB(flow block) of the present invention.
Fig. 5 is the result that transient response of amplifier is arranged
Fig. 6 is a kind of Fiber Optical Communication System schematic diagram.
Fig. 7 is testing fiber transmission link and present embodiment measurement mechanism schematic diagram.
Fig. 8 is for adopting the final measured waveform figure of the inventive method.
Fig. 9 is for adopting the strange land instrumentation plan of the inventive method.
The light signal that embodiment the present invention proposes transmission delay measurement method and device in transmission link reach accompanying drawing in conjunction with the embodiments and are described in detail as follows:
A kind of light signal transmission delay measurement method embodiment in transmission link that the present invention proposes is characterized in that, tested optical fiber and measuring system are connected into ring-type; May further comprise the steps:
1) gives straightening time signal to tested Transmission Fibers injection;
2) adjust the direct current optical signal power that returns through Transmission Fibers, make the direct current optical signal power that returns and inject direct current optical signal power coupling;
3) in tested Transmission Fibers, inject the sensed light signal of certain-length, some cycles again, this sensed light signal is transmitted in the tested optical fiber looped cycle;
4) detect the cyclic variation of this sensed light signal power according to receiving terminal, judge the transmission delay of light signal in loop;
(1) when detected optical signal power waveform has periodicity overlapping peak about one 2 times, then inject the light signal time and delay time greater than tested Transmission Fibers, therefore tested Transmission Fibers transmission delay is detected optical signal power wave period;
(2) when detected optical signal power waveform has periodicity not have the depression of light signal, then inject the light signal time and delay time less than tested Transmission Fibers, therefore tested Transmission Fibers transmission delay is detected optical signal power wave period;
(3) when detected optical signal power waveform is straight line, then injects the light signal time and delay time identical with tested Transmission Fibers.
5) according to measured tested Transmission Fibers time-delay, adjust and inject sensed light signal length, make it less than tested optical fiber time-delay 1～200 microsecond that records, adjust the tested Transmission Fibers transmission delay of input, make the time-delay of its tested optical fiber that equals just to have recorded, more set by step 4) continue accurately to measure tested Transmission Fibers time-delay;
6) carry out step 5) repeatedly and measure, twice measuring result error obtains the result this moment and is tested Transmission Fibers time-delay less than the certainty of measurement requirement up to front and back.
7) to the correction of measuring system error: by the Transmission Fibers of said measurement known signal transmission delay, the difference that obtains measurement result and this known signal transmission delay is a systematic error; The result who measures in the said step 6) is deducted systematic error, obtain tested Transmission Fibers time-delay.
The present invention proposes to adopt the method for measurement of loop structure, has eliminated the pulse generation time to a great extent, and detection time and data processing time are to the influence of measurement result.
Because the signal power that photo-detector obtains is to change in the cycle with the loop transmission delay, common sampling oscilloscope just can obtain stable signal power waveform.And the feature of signal power waveform is relevant with the size of injecting signal length and the true transmission delay of optical fibre ring transmission link, following three kinds of situations are specifically arranged:, inject signal less than true loop transmission delay, and it is identical to inject the true loop transmission delay of signal time fundamental sum.Waveform according to different situations down-sampling oscilloscope shows can measure the time-delay of signal in fiber transmission link.
When injecting signal time greater than true loop transmission delay, injecting the signal end overlaps with the injection signal front end that returns through fiber transmission link at the three-dB coupler place, so the signal power waveform that photo-detector obtains has a periodic signal less than the overlapping peak of 3dB (2 times) for being the cycle with the fiber transmission link transmission delay.
When injecting signal time less than true loop transmission delay, it is terminal by behind the three-dB coupler to inject signal, and the front end that also will inject signal a period of time just returns three-dB coupler by fiber transmission link.Have one section not have light signal between injection signal front and back end like this, the power waveform that obtains in photo-detector shows as periodic depression.
When the true loop transmission delay of injection signal time fundamental sum was identical, this moment, the cyclic variation of signal was not obvious, and the power waveform that photo-detector obtains is straight line substantially.
In order to reduce the complexity of measurement, and the too big injury possible to system of luminous power, the present invention handles the optical switch of control signal transmission, makes to measure to avoid occurring the phenomenon that signal overlaps.The optical switch action is set as shown in Figure 3, optical switch 2 is only just opened after optical switch 1 is closed during injection, delays time greater than optical fiber link if inject signal length this moment, and the head that injects signal will be disconnected by optical switch 2, thereby avoid the signal overlapping.
Measuring light signal of the present invention transmission delay device example structure in transmission link is installed as shown in Figure 2 by LASER Light Source, loop control unit, and two optical switches, the 3dB optical coupler, high speed photodetector and sampling oscilloscope are formed.Its connecting relation is: the output of this LASER Light Source output, power-adjustable attenuator links to each other with the input of optical coupler by optical switch 1, optical switch 2 respectively, an output of optical coupler links to each other with sampling oscilloscope by photo-detector, another output of optical coupler is the output of this measurement mechanism, and the input of power-adjustable attenuator is the input of this measurement mechanism.
The operation principle of this measurement mechanism is: the direct current light that laser produces is by the optical switch 1 by loop control unit control, one section optical signals three-dB coupler is injected the tested optical fiber link of loop, and three-dB coupler is told the signal that transmits in one tunnel tested optical fiber link with the signal that transmits in the loop and is sent into photo-detector through the power-adjustable attenuator by three-dB coupler simultaneously.Optical switch 2 is to be used for removing residue signal in the ring, prevents to disturb.
It is the single-chip computer control system of core by the 80c552 chip that the loop control unit of this measurement mechanism can be one, comprise the numeric keypad input, the digital demonstration as man-machine interface, with the control signal output of optical switch control interface coupling, the main action of this measurement mechanism realizes by loop control unit.The control voltage that loop control unit produces is controlled the switch of optical switch 1 and optical switch 2 respectively.When control voltage when being high, optical switch closure, light signal can pass through from optical switch; When control voltage when low, optical switch disconnects, light signal can not pass through from optical switch.Loop control unit has two kinds of operating states, and its control signal all is high during initial condition, and two optical switches are all closed.Its control signal is by the injection signal length of loop control unit keyboard input during test mode, and the tested Transmission Fibers transmission delay and the transmission number of turns are determined.As shown in Figure 3, injecting signal length T1 is the time of optical switch 1 closure, is called injection length; Transmission number of turns N multiply by tested Transmission Fibers transmission delay length T 2 for the time of optical switch 2 closures, is called the transmission time; After transmission time, a bit of clear ring time T 3 is arranged, this moment, optical switch 1,2 all disconnected; Clear ring comes back to injection length after the time, and circulation is measured like this.In test mode, loop control unit is according to the injection signal length of tester in the numeric keypad input, the tested Transmission Fibers transmission delay and the transmission number of turns produce above-mentioned optical switch control signal, after input is finished each time, when beginning to measure, press start button, two optical switches will disconnect simultaneously, enter the time of encircling clearly, unclamp start button, loop control unit is promptly started working from the injection length state.
Device in the present embodiment is: distribution bragg feedback (DFB) laser, 2 of Civcom Free-1x2 optical switches (following optical switch 1 and the optical switch 2 of abbreviating as respectively), three-dB coupler, photo-detector, HP54603B sampling oscilloscope, bandwidth 60M
The method of measurement of present embodiment, as shown in Figure 4.May further comprise the steps:
1. open Distributed Feedback Laser and photo-detector part, it is initial condition that loop control unit is set, and measuring testing apparatus output optical signal power is power 1.
2. close laser, the I/O of testing apparatus and the input/output terminal of tested optical fiber link be connected, the detection fiber link normally whether.As normally, open laser, undesired, reconnect optical fiber link.
3. adjusting adjustable attenuator, measuring by the luminous power behind the optical switch 2 is power 2, guaranteed output 2 equals the twice of power 1.
4. close laser, connect optical switch 2 and coupler, from the injection length length that the loop control unit input is estimated, the tested Transmission Fibers transmission delay and the transmission number of turns are made as test mode with loop control unit.Note, injection length length can be from little estimation, as is roughly 1/10th of Transmission Fibers transmission delay to be measured, and tested Transmission Fibers transmission delay can be estimated bigger a little, as being roughly 1～2 times of Transmission Fibers transmission delay to be measured, the transmission number of turns is also got 2～3 circles and is got final product.
5. open laser, can obtain the optical signal power waveform from the sampling oscilloscope of receiving terminal.In the cycle of measuring-signal waveform, delay time as tested optical fiber.To inject signal length by less than just recording tested optical fiber 50 microseconds of delaying time, tested Transmission Fibers transmission delay remeasures by just recording tested optical fiber time-delay input loop control unit.
6. duplicate measurements, the difference of the tested optical fiber time-delay that twice measures up to front and back is less than oscillographic resolving accuracy or less than the measurement requirement precision, and the signal period length that obtain this moment is the optical fiber link transmission delay.
As the link to be measured that contains image intensifer, can be used for measuring according to the amplifier transient effect.Its mode is the same with normal measurement, but because amplifier transient effect, can see that on oscilloscope signal front end power is exaggerated device and significantly amplifies, with this power is that the period T of sign is signal transmission delay in optical fiber link, as shown in Figure 5, it is very short to inject signal length, and that the tested optical fiber transmission delay is set at is very long, at every section rising edge that injects signal pointy power peak is arranged all, its power is far longer than the optical signal power under the normal condition.
At last measurement result is carried out systematic error and proofread and correct, promptly from total Optical Fiber Transmission loop, remove the additional transmission delay of measurement mechanism, as coupler, optical switch, adjustable optical attenuator, the transmission delay of wire jumper etc. can obtain accurate optical fiber link transmission delay.And these additional transmission delays can determine that the transmission delay relative fixed of device itself is systematic error by the optical fiber of measuring one section constant transmissions time-delay, can avoid by measurement result is proofreaied and correct.
The practical application of adopting the inventive method and device to carry out the fiber transmission link Time delay measurement illustrates as follows:
Tested object is the local communication system of A to B, and test purpose is to wish to obtain the transmission delay of accurate light signal from A to the B place.Because the input/output terminal of this link can not be directly connected to the I/O of this testing apparatus, so taked indirect measurement in actual measurement at a distance of too far away.Consideration is in actual conditions, and point-to-point Fiber Optical Communication System is made of two relative optical fiber links of direction of transfer, and the Transmission Fibers of these two optical fiber links also exists in the same optical cable, and link structure is symmetry fully.The optical fiber link structure as shown in Figure 6 in the example, the optical fiber link that is divided into two incorgruous transmission, every link is formed by conventional monomode fiber (SMF) and the online Erbium Doped Fiber Amplifiers EDFAs (EDFA-inline) of 4 sections each about 80km, wherein two links are used as the conventional monomode fiber of transmission in same optical cable, therefore with dashed lines box indicating among the figure can be similar to and think that the transmission delay of two links is identical.In measurement of the present invention, test point is the A place, therefore at the B place with the far-end articulating of two links, constitute a loop.So just can measure this total transfer delay of link back and forth, and the propagation delay time between the AB is 1/2 of an overall transmission delay at the A place.Whole testing fiber transmission link and measurement mechanism as shown in Figure 7, by Distributed Feedback Laser, optical switch 1,2, loop control unit, three-dB coupler, photo-detector, sampling oscilloscope, adjustable attenuator, 8 sections Transmission Fibers (SMF) and corresponding Erbium Doped Fiber Amplifiers EDFAs (EDFA) are formed.The control signal of loop control unit outputs to optical switch 1,2 respectively; The result of photo-detector gives sampling oscilloscope; The light of Distributed Feedback Laser output is connected to left end one arm of three-dB coupler by optical switch 1, and another arm of three-dB coupler left end connects optical switch 2; Three-dB coupler right-hand member one arm connects photo-detector, and an arm is connected to the input of testing fiber link; The output of testing fiber link is connected on the adjustable optical attenuator, and an end of the other end of this attenuator and optical switch 2 is connected.
At first, it is initial condition that loop control unit is set, and opens Distributed Feedback Laser, is power 1 at device measurement of output end output signal power.Close laser then, the output of testing apparatus is connected the input of fiber links to be measured, the input of testing apparatus connects the output of fiber links to be measured.Open laser,, adjust adjustable optical attenuator, make it equal power 2 in optical switch 2 back measured signal power.
Then, close laser, reconnected adjustable attenuator and optical switch, and loop control unit is made as test mode, from the keyboard input of loop control unit initial the injection signal length and the transmission number of turns.Open laser, can obtain the signal power waveform this moment from oscilloscope.In theory, initial injection signal length does not have concrete requirement with the setting of transmitting the number of turns.But because fiber optic transmission system is not a linear system completely, the analysis of front only is a principle.In real system, because amplifier noise and the saturated effect of amplifier gain, when injecting signal length less than the optical fiber link transmission delay, depression breach in the waveform can not keep always, through after the transmission of multi-turn, the spontaneous emission noise power of depression barbed portion will become big and this depression breach will be remedied, and therefore former circles of generally getting circle transmission influence measurement effect to avoid transmission system to the nonlinear interaction of signal power as the Measuring Time section.Be made as 3 circles such as transmitting the number of turns, optical switch 2 will disconnect after the time in 3 times of injections of unlatching signal lengths so, and to remove the last signal that injects, injection restarts next time simultaneously.Exactly because the spontaneous emission noise of amplifier, the influence of gain saturation and amplifier transient state, therefore best measurement state is to inject signal length to be slightly less than the optical fiber link transmission delay.Consider the amplifier that may exist in the fiber transmission link again to power monitoring, this amplifier can automatically shut down (general unglazed state continuance surpasses ms) when no light state is longer, can exert an influence to measured waveform like this, make the gauger can not differentiate normal waveform depression breach.In order to make method of measurement general, the injection signal length of initial setting generally should be littler than optical fiber link transmission delay, and the transmission number of turns is made as 2～3 circles.Measure optical fiber loop transmission delay (influence that this measurement result may be turn-offed by amplifier is bigger than normal) from oscilloscope, the optical fiber loop transmission delay of measuring can be reduced 1～100 microsecond then as injecting signal length, signal waveform is measured, if at this moment measurement result and last time close, just can exclude this unglazed automatically shut down and to inject signal too short and do not dispose the situation of the last signal that injects.Because this optical fiber link has amplifier, so after basic definite optical fiber link time-delay, injection length is reduced tens microseconds, can obtain the waveform of transient peak this moment, and signal waveform has very high periodicity spike, is easy to obtain its cycle.Generally as shown in Figure 8, obtain the T1 of cyclic injection signal length more clearly, measurement period T, the breach T4 of no signal condition in the loop from oscilloscope.For better and data are set relatively, tested Transmission Fibers transmission delay T2 and transmission number of turns N (N=2) have also been marked among the figure.The power peak of injecting the signal front end among the figure is that the transient effect by EDFA produces.Notice that if inject the injection signal length value (deviation is very big) that signal length is not equal to setting in the waveform, it is incorrect then to measure state, the injection signal length of She Zhiing is too short probably, and twice signal has interference before and after causing, and reset the injection signal length.
Be the rectification of measurement result being carried out systematic error at last.If in measurement, do not add other parts, can directly from measurement result, deduct the transmission delay t that measurement mechanism introduces so and get final product except measurement mechanism.If introduced other parts, as amplifier, wire jumper etc., the testing fiber transmission link is promptly skipped in the time-delay that then needs to measure these parts, and remainder is measured its transmission delay as the testing fiber link.This situation generally appears at during the strange land measures, and as shown in Figure 9, A, B, C be by three indirect place's nodes of bidirectional optical fiber link, its order of connection be A to B to C or C arrive A to B.Measurement mechanism needs to measure the optical fiber link transmission delay of B to the C place at the A place.Can measure respectively like this A to the transmission delay of C and A to the transmission delay of B, just can obtain the optical fiber link transmission delay of B to C.
Claims (4)
1, a kind of light signal transmission delay measurement method in transmission link is characterized in that, tested optical fiber and measuring system are connected into ring-type; May further comprise the steps:
1) injects preset direct current light signal to tested Transmission Fibers;
2) adjust the direct current optical signal power that returns through Transmission Fibers, make the direct current optical signal power that returns and inject direct current optical signal power coupling;
3) in tested Transmission Fibers, inject the sensed light signal of certain-length, some cycles again, this sensed light signal is transmitted in the tested optical fiber looped cycle;
4) detect the cyclic variation of this sensed light signal power according to receiving terminal, judge the transmission delay of light signal in loop:
(1) when detected optical signal power waveform has periodicity not have the depression of light signal, then inject the light signal time and delay time less than tested Transmission Fibers, therefore tested Transmission Fibers time-delay is detected optical signal power wave period;
(2) when detected optical signal power waveform is straight line, then injects the light signal time and delay time identical with tested Transmission Fibers.
2, light signal as claimed in claim 1 transmission delay measurement method in transmission link also comprises:
5) the tested Transmission Fibers time-delay that obtains according to the judgement in the described step 4), adjust and inject sensed light signal length, make it less than tested Transmission Fibers time-delay 1～200 microsecond that records, adjust the tested Transmission Fibers time-delay of input, make tested Transmission Fibers time-delay that it equals just to have recorded, more set by step 4) continue accurately to measure tested Transmission Fibers time-delay;
6) carry out step 5) repeatedly and measure, twice measuring result error obtains the result this moment and is tested Transmission Fibers time-delay less than the certainty of measurement requirement up to front and back.
3, light signal as claimed in claim 2 transmission delay measurement method in transmission link is characterized in that also comprising:
7) to the correction of measuring system error: by the Transmission Fibers of said measurement known signal transmission delay, the difference that obtains measurement result and this known signal transmission delay is a systematic error; With said step 4) or 6) in the result that measures deduct systematic error, obtain tested Transmission Fibers time-delay.
4, a kind of light signal transmission delay measurement mechanism in transmission link is characterized in that, comprises the LASER Light Source that is used for injecting to tested Transmission Fibers light signal; Be used to adjust the power-adjustable attenuator of optical signal power; Be used for the light signal of this light source is modulated into first optical switch and second optical switch of periodic signal; Be used to control the loop control unit of this optical switch time, light signal injected the optical coupler of tested Transmission Fibers; And the data processing equipment that light signal is handled; Its annexation is: the output of this LASER Light Source output, power-adjustable attenuator links to each other with two arms of optical coupler one end by first optical switch, second optical switch respectively, one arm of the optical coupler other end links to each other with data processing equipment, another arm of another end of optical coupler is the output of this measurement mechanism, and the input of power-adjustable attenuator is the input of this measurement mechanism.
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| GB2425904A (en) * | 2005-05-03 | 2006-11-08 | Marconi Comm Gmbh | Optical network fault test apparatus which modifies a received test signal using a passive optical device to generate a response signal |
| US8180216B2 (en) * | 2007-12-20 | 2012-05-15 | Verizon Patent And Licensing Inc. | Latency measurement in optical networks |
| CN103441795A (en) * | 2013-08-29 | 2013-12-11 | 成都泰富通信有限公司 | Online monitoring method for optical fiber transmission delay in optical communication network |
| CN104426600B (en) * | 2013-09-04 | 2017-01-11 | 成都泰富通信有限公司 | Automatic optical fiber transmission delay locking and equalization method |
| CN105553543B (en) * | 2015-12-24 | 2018-04-24 | 中国电子科技集团公司第四十一研究所 | A kind of coherent light time domain reflection meter calibrating device and method |
| CN112097753B (en) * | 2020-09-14 | 2023-07-07 | 湖南航天机电设备与特种材料研究所 | Method and system for detecting optical fiber ring phase change point |
| CN113328793A (en) * | 2021-06-17 | 2021-08-31 | 西北核技术研究所 | Remote optical fiber transmission delay testing method and system based on time domain reflection difference |
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