CN102223184A - Dispersion compensation method and device - Google Patents
Dispersion compensation method and device Download PDFInfo
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- CN102223184A CN102223184A CN2011101753527A CN201110175352A CN102223184A CN 102223184 A CN102223184 A CN 102223184A CN 2011101753527 A CN2011101753527 A CN 2011101753527A CN 201110175352 A CN201110175352 A CN 201110175352A CN 102223184 A CN102223184 A CN 102223184A
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Abstract
The invention discloses a dispersion compensation method and device, wherein the dispersion compensation method comprises the steps of obtaining the feedback signal values of a PT module under different TDC (Time Delay Compensation) dispersion values; carrying out curve fitting on the feedback signal values and obtaining dispersion adjusting values; and carrying out dispersion adjustment on the TDC dispersion values by the dispersion adjusting values. The method and the device solve the problem that a business veneer based on a polarization tracking technology in the current optical transmission network can not utilize the peak signal contrast of a balance receiver to realize the coarse adjustment of TDC dispersion, thus realizing the demultiplexing of the polarized light; even when the PT module does not carry out demultiplexing on the polarized light, the effect of coarse adjustment on TDC can be realized effectively.
Description
Technical field
The present invention relates to the communications field, in particular to a kind of dispersion compensation method and device.
Background technology
In the long Distance Transmission process of wavelength-division,, cause system to produce effect of dispersion because of multiple factors such as environment, optical fiber, equipment.Though each transmission website can adopt the partial dispersion compensation technique to improve, the entire compensation inaccuracy.Yet,,, do not have special dispersion compensation unit to work, so the equipment of chromatic dispersion compensating function is essential as single ripple 40G or 100G equipment for the optical channel equipment of high rate data transmission.
Existing DQPSK (Differential Quadrature Phase Shift Keying, difference quadrature phase shift keying) modulation down, the dispersion compensation technology mainly is to utilize the chromatic dispersion of balanced reciver peak signal contrast realization TDC (dispersion compensation adjustment) to adjust roughly, search for the minimum value of balanced reciver peak signal then, find ± 45 DLI (the Delay Line Interferometer that spend, delay line interferometer) coarse phase, the preceding error code information of the error correction that utilizes framer to provide is at last finely tuned TDC chromatic dispersion and fine setting DLI phase place successively, the final TDC of realization chromatic dispersion is fixed optimum, and the DLI phase place continues to follow the tracks of fine setting.
For PM-DQPSK, i.e. palarization multiplexing-difference quadrature phase shift keying modulation system, receiving terminal adopts delayed interference and balance to receive and realizes input.Because of input signal is 2 tunnel polarization state signals, need to adopt the optical polarization tracking technique to isolate the DQPSK signal of 2 road polarized orthogonals.Polarization tracking (PT) module that the optical polarization tracking technique is adopted need could reduce crosstalking between two polarised lights in certain dispersion range, two polarised lights are separated.When module was unrealized the polarization optics demultiplexing, the balanced reciver peak signal was unavailable at PT (biasing is followed the tracks of), also just can not utilize balanced reciver peak signal contrast realization TDC chromatic dispersion to adjust roughly, also just can not realize dispersion compensation.
Summary of the invention
Main purpose of the present invention is to provide a kind of dispersion compensation method and device, and the service board based on the polarization tracking technology can't utilize balanced reciver peak signal contrast to realize the rough problem of adjusting of TDC chromatic dispersion in the above-mentioned present optical transmission network to solve at least.
According to an aspect of the present invention, provide a kind of dispersion compensation method, having comprised: obtained under different TDC dispersion values the feedback signal value of PT module; Feedback signal value is carried out curve fitting, obtain the chromatic dispersion adjusted value; According to the chromatic dispersion adjusted value TDC dispersion values is carried out the chromatic dispersion adjustment.
Preferably, obtaining under different dispersion compensations adjustment TDC dispersion values, after the step of the feedback signal value of biasing tracking PT module, also comprise: abandon under the dispersion point of the setpoint distance that departs from the actual dispersion value feedback signal value of PT module.
Preferably, abandon under the dispersion point of the setting quantity that departs from the actual dispersion value, the step of the feedback signal value of PT module comprises: the dispersion point with minimum value in the TDC dispersion values is the center, about respectively get 4 continuous dispersion points, obtain 9 continuous dispersion points; Obtain the feedback signal value of PT module under 9 dispersion points, abandon the feedback signal value of PT module under other dispersion point.
Preferably, feedback signal value is carried out curve fitting, the step of obtaining the chromatic dispersion adjusted value comprises: compare feedback signal value, find minimum point as the center; About this center, respectively get first point of setting quantity and carry out the binomial match, obtain first matched curve; Minimum point with first matched curve is the center, respectively gets second point of setting quantity and carry out Gauss curve fitting about this center, obtains second matched curve; According to second matched curve, obtain the chromatic dispersion adjusted value.
Preferably, obtain at different dispersion compensations and adjust under the TDC dispersion values, the step that the feedback signal value of PT module is followed the tracks of in biasing comprises: with 100 ps/nm is step-length, and the dispersion values in the whole threshold range is adjusted; Adjust point at each and carry out the collection of the feedback signal value of PT module.
Preferably, obtaining under different dispersion compensations adjustment TDC dispersion values, after the step of the feedback signal value of biasing tracking PT module, also comprising: 1 millisecond at every interval, read feedback signal value 1000 times from Serial Peripheral Interface SPI; 1000 feedback signal values that read are done on average, obtained feedback signal value after average as final feedback signal value.
Preferably, this dispersion compensation method is applied to the 100G optical transmission of polarization tracking.
According to a further aspect in the invention, provide a kind of dispersion compensation device, having comprised: main control module and TDC module, wherein, main control module comprises: the feedback signal module is used to obtain under different TDC dispersion values the feedback signal value of PT module; Curve fitting module is used for feedback signal value is carried out curve fitting, and obtains the chromatic dispersion adjusted value, and sends to the TDC module; The TDC module is used for according to the chromatic dispersion adjusted value TDC dispersion values being carried out the chromatic dispersion adjustment.
Preferably, main control module also comprises: abandon module, be used for obtaining under different dispersion compensations adjustment TDC dispersion values in the feedback signal module, biasing is followed the tracks of after the feedback signal value of PT module, abandon under the dispersion point of the setpoint distance that departs from the actual dispersion value feedback signal value of PT module.
Preferably, abandon module and be used for obtaining at different dispersion compensations in the feedback signal module and adjust under the TDC dispersion values, biasing is followed the tracks of after the feedback signal value of PT module, is the center with the dispersion point of minimum value in the TDC dispersion values, about respectively get 4 continuous dispersion points, obtain 9 continuous dispersion points; Obtain the feedback signal value of PT module under 9 dispersion points, abandon the feedback signal value of PT module under other dispersion point.
Preferably, curve fitting module comprises: first fitting module, be used for the comparison feedback signal value, and find minimum point as the center; About this center, respectively get first point of setting quantity and carry out the binomial match, obtain first matched curve; Second fitting module, the minimum point that is used for first matched curve is the center, respectively gets second point of setting quantity and carry out Gauss curve fitting about this center, obtains second matched curve; Obtain sending module, be used for obtaining the chromatic dispersion adjusted value, and send to the TDC module according to second matched curve.
Preferably, it is step-length that the feedback signal module is used for 100 ps/nm, and the dispersion values in the whole threshold range is adjusted; Adjust point at each and carry out the collection of the feedback signal value of PT module.
By the present invention, adopt the feedback signal value of gathering PT module under the different TDC dispersion values, and the feedback signal value that collects carried out curve fitting to obtain the chromatic dispersion adjusted value, by the chromatic dispersion adjusted value TDC dispersion values is adjusted, solved the problem that to utilize the rough adjustment of balanced reciver peak signal contrast realization TDC chromatic dispersion in the present optical transmission network based on the service board of polarization tracking technology, and then reached the demultiplexing of realizing polarised light, even during not to the polarised light demultiplexing, also can effectively realize the effect of the rough adjustment of TDC in the PT module.
Description of drawings
Accompanying drawing described herein is used to provide further understanding of the present invention, constitutes the application's a part, and illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute improper qualification of the present invention.In the accompanying drawings:
Fig. 1 is the flow chart of steps according to a kind of dispersion compensation method of the embodiment of the invention one;
Fig. 2 is the flow chart of steps according to a kind of dispersion compensation method of the embodiment of the invention two;
Fig. 3 is a kind of flow chart of steps based on the rough adjustment of TDC under the PT control according to the embodiment of the invention three;
Fig. 4 is the structured flowchart according to a kind of dispersion compensation device of the embodiment of the invention four;
Fig. 5 is the structural representation according to a kind of dispersion compensation device of the embodiment of the invention five;
Fig. 6 is the structural representation according to a kind of dispersion compensation device of the embodiment of the invention six;
Fig. 7 is the structural representation of the PT module in the device shown in Figure 6;
Fig. 8 (a) and Fig. 8 (b) are the graphs of a relation that application drawing 6 shown devices carry out in the chromatic dispersion adjustment process two kinds of different dispersion values and PT module feedback signal value;
Fig. 9 is the schematic diagram according to a kind of application scenarios based on the rough adjusting device of TDC under the PT control of the embodiment of the invention.
Embodiment
Hereinafter will describe the present invention with reference to the accompanying drawings and in conjunction with the embodiments in detail.Need to prove that under the situation of not conflicting, embodiment and the feature among the embodiment among the application can make up mutually.
Embodiment one
With reference to Fig. 1, show flow chart of steps according to a kind of dispersion compensation method of the embodiment of the invention one.
The dispersion compensation method of present embodiment may further comprise the steps:
Step S102: obtain under different TDC dispersion values the feedback signal value of PT module;
In whole threshold value, the TDC dispersion values to be carried out in the adjustment process, each adjusts the feedback signal value that point is gathered a PT module, thereby realizes under the different TDC dispersion values, the obtaining of PT module feedback signal value.
Step S104: feedback signal value is carried out curve fitting, obtain the chromatic dispersion adjusted value;
The feedback signal value that obtains is carried out curve fitting, to obtain the chromatic dispersion adjusted value an of the best.
Step S106: the TDC dispersion values is carried out the chromatic dispersion adjustment according to the chromatic dispersion adjusted value.
This chromatic dispersion adjusted value is sent to the TDC module, adjusts roughly so that the TDC dispersion values is carried out chromatic dispersion.
In the correlation technique, when the PT module was unrealized the polarization optics demultiplexing, the balanced reciver peak signal was unavailable, also just can not utilize balanced reciver peak signal contrast realization TDC chromatic dispersion to adjust roughly, and then can not realize dispersion compensation.Pass through present embodiment, adopt the feedback signal value of gathering PT module under the different TDC dispersion values, and the feedback signal value that collects carried out curve fitting to obtain the chromatic dispersion adjusted value, by the chromatic dispersion adjusted value TDC dispersion values is adjusted, solved the problem that to utilize the rough adjustment of balanced reciver peak signal contrast realization TDC chromatic dispersion in the present optical transmission network based on the service board of polarization tracking technology, and then reached the demultiplexing of realizing polarised light, even during not to the polarization optics demultiplexing, also can effectively realize the effect of the rough adjustment of TDC in the PT module.
Embodiment two
With reference to Fig. 2, show flow chart of steps according to a kind of dispersion compensation method of the embodiment of the invention two.
The dispersion compensation method of present embodiment may further comprise the steps:
Step S202:, gather the feedback signal value of PT module under the different dispersion values by adjusting the TDC dispersion values in the whole threshold value.
Generally speaking, expression chromatic dispersion adjusting range is-threshold range of 700ps/nm～700ps/nm in the whole threshold value, and wherein, ps/nm represents ps/nm.But be not limited thereto, it will be appreciated by those skilled in the art that present embodiment is equally applicable to other chromatic dispersion adjusting range.
Step S204: owing to departing from actual dispersion value dispersion point far away, the feedback signal value approximately equal of PT module can not correctly be reacted the curved line relation of dispersion values and feedback signal value, so need abandon the data of dispersion point far away.
Wherein, depart from actual dispersion value dispersion point far away and be meant the dispersion point that departs from actual dispersion value setpoint distance, as the dispersion point with minimum value in the TDC dispersion values is the center, each gets 4 dispersion points continuously to the left and right, obtain 9 continuous dispersion points thus, and other dispersion point can be thought to depart from actual dispersion value dispersion point far away and abandon.Certainly, be not limited thereto in actual applications, those skilled in the art can suitably set the distance that departs from actual dispersion point according to actual conditions, and the present invention does not limit this.
Step S206: the relation according between the feedback signal value of TDC dispersion values and the PT module that collects carries out curve fitting to feedback signal value, to find best coarse adjustment dispersion values (being the chromatic dispersion adjusted value).
Step S208: the best coarse adjustment dispersion values that curve fit is obtained sends to the TDC module, and the TDC dispersion values is carried out the chromatic dispersion adjustment.
After having realized the rough adjustment of TDC effectively, and then can utilize the minimum value of balanced reciver peak signal, find ± the 45 DLI coarse phase of spending, the preceding error code information of the error correction that utilizes framer to provide is at last finely tuned TDC chromatic dispersion and fine setting DLI phase place successively, the final TDC of realization chromatic dispersion is fixed optimum, and the DLI phase place continues to follow the tracks of fine setting.
Preferably, with big step-length, step value is preferably 100ps/nm, carries out the adjustment of whole threshold range internal dispersion value, when each adjustment point carries out a PT module feedback signal collection, the feedback signal of PT module can be by SPI (the Serial Peripheral Interface of module, Serial Peripheral Interface) port directly reads, and the variation that the size of feedback signal is not stopped within the specific limits need be done multiple averaging and reduce accident error, be preferably 1000 times, the polling interval is 1ms.
Pass through present embodiment, abandon and depart from actual dispersion value dispersion point far away, and, make curve fit more near actual conditions at this feedback signal value of putting the PT module of gathering, the chromatic dispersion adjusted value that obtains is more reasonable, and then can more effectively carry out the chromatic dispersion adjustment to the TDC dispersion values.
Embodiment three
With reference to Fig. 3, show a kind of flow chart of steps based on the rough adjustment of TDC under the PT control according to the embodiment of the invention three.
The rough adjustment of TDC based under the PT control of present embodiment may further comprise the steps:
Step S302: adjust a TDC dispersion values every 100ps/nm.
Step S304: the PT module feedback signal value of gathering this adjustment point.
Step S306: judging whether the TDC dispersion values is adjusted in the TDC threshold range finishes, if, execution in step S308; If not, then returning step S302 continues to carry out.
Step S308: abandon at the feedback signal value that departs from the PT module of gathering under the dispersion point far away of actual dispersion value.
Wherein, dispersion point far away is meant the dispersion point that departs from actual dispersion value setpoint distance, as the dispersion point with minimum value in the TDC dispersion values is the center, each gets 4 dispersion points continuously to the left and right, obtain 9 continuous dispersion points thus, and other dispersion point can be thought to depart from actual dispersion value dispersion point far away and abandon.Certainly, be not limited thereto in actual applications, those skilled in the art can suitably set the distance that departs from actual dispersion point according to actual conditions, and the present invention does not limit this.
Step S310: the feedback signal value that collects is carried out the binomial match.
In this step,, at first find minimum point, about this center, respectively get first point of setting quantity then and carry out the binomial match, obtain first matched curve as the center to having abandoned than all the other feedback signal values behind the feedback signal value under the dispersion point far away.Wherein, first sets quantity suitably is provided with according to actual conditions by those skilled in the art, as first when 15 feedback signal values are set to set quantity be 4 or the like, the present invention does not limit for this reason.
Step S312: the feedback signal value that has carried out the binomial match is carried out Gauss curve fitting.
In this step, to the feedback signal value in first matched curve after the binomial match of having passed through step S310, getting its minimum point is the center, respectively gets second point of setting quantity and carry out Gauss curve fitting about this center, obtains second matched curve.Wherein, second sets quantity suitably is provided with according to actual conditions by those skilled in the art, and the present invention does not limit this.
Step S314:, determine the chromatic dispersion adjusted value according to having carried out second matched curve after the Gauss curve fitting.
Step S316:, original TDC dispersion values is carried out the chromatic dispersion adjustment according to the chromatic dispersion adjusted value.
Need to prove, be example with binomial match and Gauss curve fitting in the present embodiment, and curve fit of the present invention is explained.But be not limited thereto, it will be appreciated by those skilled in the art that embodiments of the invention are applicable to the curve fit mode that other is suitable too.
By present embodiment, effectively realized being unrealized maybe can not realize the polarization optics demultiplexing time the rough adjustment of TDC dispersion values in the PT module.The binomial match of present embodiment and Gauss curve fitting realize simple, and can determine the chromatic dispersion adjusted value preferably, so that the TDC dispersion values is effectively adjusted.
Embodiment four
With reference to Fig. 4, show structured flowchart according to a kind of dispersion compensation device of the embodiment of the invention four.
The dispersion compensation device of present embodiment comprises: main control module 402 and TDC module 404.Wherein, main control module 402 comprises: feedback signal module 4022 is used to obtain under different TDC dispersion values the feedback signal value of PT module; Curve fitting module 4024 is used for feedback signal value is carried out curve fitting, and obtains the chromatic dispersion adjusted value, and sends to TDC module 404.TDC module 404 is used for according to the chromatic dispersion adjusted value TDC dispersion values being carried out the chromatic dispersion adjustment.
Preferably, main control module 402 also comprises: abandon module, be used for obtaining under different TDC dispersion values in feedback signal module 4022, after the feedback signal value of PT module, abandon and depart under the actual dispersion value dispersion point far away, the feedback signal value of PT module.Wherein, dispersion point far away is meant the dispersion point that departs from actual dispersion value setpoint distance.
Preferably, curve fitting module 4024 comprises: first fitting module, be used for the comparison feedback signal value, and find minimum point as the center; About this center, respectively get first point of setting quantity and carry out the binomial match, obtain first matched curve; Second fitting module, the minimum point that is used for first matched curve is the center, respectively gets second point of setting quantity and carry out Gauss curve fitting about this center, obtains second matched curve; Obtain sending module, be used for obtaining the chromatic dispersion adjusted value, and send to TDC module 404 according to second matched curve.
Preferably, it is step-length that feedback signal module 4022 is used for 100ps/nm, and the dispersion values in the whole threshold range is adjusted; Adjust point at each and carry out the collection of the feedback signal value of PT module.
Preferably, main control module 402 also comprises: the mean value module, be used for obtaining under different TDC dispersion values in feedback signal module 4022, and after the feedback signal value of PT module, read once for 1 millisecond at every interval, reads feedback signal value 1000 times from SPI; 1000 feedback signal values that read are done on average, obtained feedback signal value after average as final feedback signal value.
Preferably, the dispersion compensation device of present embodiment also comprises: compensating module, be used for TDC module 404 is carried out the chromatic dispersion adjustment to the TDC dispersion values according to the chromatic dispersion adjusted value after, according to the minimum value of adjusted TDC dispersion values of chromatic dispersion and balanced reciver peak signal, original TDC dispersion values is carried out dispersion compensation.
Preferably, the dispersion compensation device of present embodiment is applied to the 100G optical transport technology of polarization tracking scheme.
Pass through present embodiment, solved the problem that to utilize the rough adjustment of balanced reciver peak signal contrast realization TDC chromatic dispersion in the present optical transmission network based on the service board of polarization tracking technology, and then reached the demultiplexing of realizing polarised light, even during not to the polarised light demultiplexing, also can effectively realize the effect of the rough adjustment of TDC in the PT module.
Embodiment five
With reference to Fig. 5, show structural representation according to a kind of dispersion compensation device of the embodiment of the invention five.
The dispersion compensation device of present embodiment comprises:
TDC module 502, this module are utilized reflection position or the transmission range different principle of light in grating of different wave length, realize pulse compression, thereby reach the effect of dispersion compensation.In the present embodiment, it also is used to receive the chromatic dispersion adjusted value that main control module 506 sends, and then the TDC dispersion values is adjusted roughly.
PT module 504, this module can follow the tracks of fast and stable fiber in the polarised light of the different directions that transmits, reduce crosstalking between two polarised lights, and the bias lighting of different directions separated by the offset separation device.In the present embodiment, it also is used to feed back the feedback signal value under the different TDC dispersion values.
Main control module 506, its major function are the feedback signal values of gathering PT module 504, and utilize curve fit to find dispersion point, obtain the chromatic dispersion adjusted value, send the chromatic dispersion adjusted value at last, make each device collaborative work, finish chromatic dispersion and adjust roughly.Main control module 506 can be realized by CPU, but be not limited thereto, the any feedback signal value that can gather PT module 504, and utilize curve fit to find dispersion point, obtain the chromatic dispersion adjusted value, send the chromatic dispersion adjusted value at last, make each device collaborative work, finish rough device or the module of adjusting of chromatic dispersion and all can realize main control module 506.
Flashlight is input to TDC module 502, enters PT module 504 behind the dispersion compensating, and PT module 504 can be followed the tracks of the polarised light of both direction fast, reduces crosstalking between two polarised lights, isolates vertical with parallel two polarised lights output then.In this process, PT module 504 only could be isolated vertical with parallel polarised light effectively in the certain chromatic dispersion allowed band of flashlight, so just need TDC module 502 to adjust roughly effectively the chromatic dispersion of input signal.In order to find the dispersion values of rough adjustment, main control module 506 is gathered the feedback signal of PT modules 504, carries out curve fitting, and finds the chromatic dispersion adjusted value, is handed down to TDC module 502 then and carries out chromatic dispersion and adjust roughly.
Present embodiment is as follows based on the rough process of adjusting of TDC under 504 controls of PT module: by adjusting the TDC dispersion values in the whole threshold value, gather the feedback signal of PT module 504 under the different dispersion values; Since departing from actual dispersion value dispersion point far away, the feedback signal approximately equal of PT module 504, and the reaction dispersion values that can not be correct and the curved line relation of feedback signal value are so need abandon the data of dispersion point far away; Carry out curve fitting according to the relation between TDC dispersion values and PT module 504 feedback signal values that collect, find best coarse adjustment dispersion values (being the chromatic dispersion adjusted value); The best coarse adjustment dispersion values that main control module 506 obtains curve fit sends to TDC module 502 and carries out the chromatic dispersion adjustment.
Pass through present embodiment, solved the problem that to utilize the rough adjustment of balanced reciver peak signal contrast realization TDC chromatic dispersion in the present optical transmission network based on the service board of polarization tracking technology, provide a kind of and adjusted scheme roughly based on TDC under the PT control easily.
Embodiment six
With reference to Fig. 6, show structural representation according to a kind of dispersion compensation device of the embodiment of the invention six.
The dispersion compensation device of present embodiment comprises: TDC module 602, PT module 604 and the main control module of being realized by CPU 606.
The chromatic dispersion adjusting range of TDC module 602 is-700ps/nm～700ps/nm that the adjusting time is a second level.TDC module 602 be can with the mutual control assembly of main control module 606, logic control device (CPLD (Complex Programmable Logic Device) or FPGA (Field Programmable Gate Array) etc.) be can comprise, actuator, hardware comparator etc. adjusted with main control module communication device, chromatic dispersion.The major function of TDC module 602 comprises: main control module 606 sends adjusts order, and the chromatic dispersion adjusted value is sent to the TDC module, and the TDC module receives the chromatic dispersion adjusted value that main control module 606 sends, and original TDC dispersion values is adjusted.
The modular structure of PT module 604 mainly comprises FPGA controller, LiNbO as shown in Figure 7
3(lithium columbate crystal), polarized Beam Splitter, coupler and RF detector.It can follow the tracks of fast and stable fiber in the polarised light of the different directions that transmits, reduce crosstalking between two polarised lights, and bias lighting vertical and parallel direction separated by the offset separation device.Then by each road polarised light of separating is monitored, the polarised light size of the other direction that wherein comprises passes in the fpga chip as feedback signal, thereby fpga chip can pass through the polarization tracking on the real-time correction main optical path of feedback signal, reduces crosstalking between two polarised lights.In addition, PT module 604 provides the external output of a SPI interface as feedback signal.
It is as follows that the device of use present embodiment carries out adjusting flow process roughly based on the TDC under the PT control:
TDC module 602 is carried out whole threshold range internal dispersion value with big step-length and is adjusted (preferably, step value is 100ps/nm), and each is adjusted point and carries out PT module 604 feedback signal value collections.The feedback signal value of PT module 604 can directly read by its SPI port, and the variation that the size of feedback signal is not stopped within the specific limits need be done multiple averaging and reduce accident error (being preferably polling interval 1ms 1000 times).
Owing to departing from actual dispersion value dispersion point far away, the feedback signal approximately equal of PT module 604, curve is more flat, can not correctly react the curved line relation of dispersion values and feedback signal value, so need abandon for departing from actual dispersion value dispersion point far away, not as the data of curve fit.
Consider that curve bottom may be more flat, and a variety of causes can cause the saltus step of feedback signal, can not determine actual dispersion in the system with the minimum value method, PT can only roughly reflect the situation of dispersion variation.When software is realized, can consider to get rid of dispersion point far away, optimum value is found out in matched curve.
Relatively the feedback signal value of each dispersion point correspondence finds minimum point as the center, respectively gets at 4 and carry out curve fitting about it, and curve fit is the binomial match for the first time, finds out approximate range; For the second time curve fit with minimum point that the first time, match obtained as the center, about respectively get at 4 and carry out Gauss curve fitting, find the optimum dispersion value, as the chromatic dispersion adjusted value.
At last, according to resulting optimum dispersion value, TDC is adjusted roughly.
In the above-mentioned adjustment, the relation of dispersion values and PT module feedback signal value is shown in Fig. 8 (a) and Fig. 8 (b).Fig. 8 (a) and Fig. 8 (b) are respectively the system dispersion value when being 0ps/nm and 320ps/nm, the graph of a relation of the feedback signal value of the dispersion values of measurement and PT module, and the curve that obtains of match.Wherein, point curve is represented the feedback signal value of the PT module of sampling, and smooth curve is represented the curve that obtains after the feedback signal value according to the PT module carries out curve fitting.
With reference to Fig. 9, show schematic diagram according to a kind of application scenarios based on the rough adjusting device of TDC under the PT control of the embodiment of the invention.
As shown in Figure 9, the TDC adjustment scheme under the DQPSK modulation comprises: transmitter unit adopts the PDM-DQPSK modulation, and receiving element adopts direct reception technique; Laser is divided into 2 tunnel orthogonal polarisation state light by polarization beam apparatus, and the DQPSK modulation is carried out on every road, and then synthesizes a branch of light with polarization beam combiner, and transmission rate is 111.8Gbps.The direct reception of phase modulated signal is promptly adopted delayed interference and balance to receive and is realized input, because of input signal is 2 tunnel polarization state signals, also need adopt the optical polarization tracking technique to isolate the DQPSK signal of 2 road polarized orthogonals.
Realize effectively based on dispersion compensation under the PT control on the rough basis of adjusting of TDC above-mentioned, and then can utilize the minimum value of balanced reciver peak signal, find ± the 45 DLI coarse phase of spending, the preceding error code information of the error correction that utilizes framer to provide is at last finely tuned TDC chromatic dispersion and fine setting DLI phase place successively, the final TDC of realization chromatic dispersion is fixed optimum, and the DLI phase place continues to follow the tracks of fine setting.
From above description, as can be seen, the invention provides and a kind ofly adjust scheme roughly based on the TDC under the PT module controls, it can provide necessary dispersion compensation to long-distance transmissions and two-forty chromatic dispersion sensitive equipment, improve the performance of optical channel access device and the interference rejection ability of wavelength-division system, solved the PM-DQPSK modulation effectively and be difficult to utilize balanced reciver peak signal contrast to realize the rough problem of adjusting of TDC down.
Compare with existing dispersion compensation technology, existing dispersion compensation technology mainly is to utilize balanced reciver peak signal contrast realization TDC chromatic dispersion to adjust roughly, when polarization tracking module (PT module) was unrealized the polarization optics demultiplexing, the balanced reciver peak signal was unavailable; Have only chromatic dispersion in allowed band, the polarization tracking module just can be finished polarization demultiplexing.In addition, utilize balanced reciver peak signal contrast to adjust the TDC chromatic dispersion roughly and only be fit to existing 40G system, and the two carrier schemes of 100G, be not suitable for the 100G optical transport technology of polarization tracking scheme.
And the present invention carries out curve fitting by the feedback signal value to the PT module, the rough TDC module of adjusting, thereby realized the polarised light demultiplexing, overcome the defective of original scheme, be particularly useful for the chromatic dispersion adjustment of TDC under the 100G optical transport technology of polarization tracking scheme.
Obviously, those skilled in the art should be understood that, above-mentioned each module of the present invention or each step can realize with the general calculation device, they can concentrate on the single calculation element, perhaps be distributed on the network that a plurality of calculation element forms, alternatively, they can be realized with the executable program code of calculation element, thereby, they can be stored in the storage device and carry out by calculation element, and in some cases, can carry out step shown or that describe with the order that is different from herein, perhaps they are made into each integrated circuit modules respectively, perhaps a plurality of modules in them or step are made into the single integrated circuit module and realize.Like this, the present invention is not restricted to any specific hardware and software combination.
The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (12)
1. a dispersion compensation method is characterized in that, comprising:
Obtain at different dispersion compensations and adjust under the TDC dispersion values, the feedback signal value of PT module is followed the tracks of in biasing;
Described feedback signal value is carried out curve fitting, obtain the chromatic dispersion adjusted value;
According to described chromatic dispersion adjusted value described TDC dispersion values is carried out the chromatic dispersion adjustment.
2. method according to claim 1 is characterized in that, adjusts under the TDC dispersion values described obtaining at different dispersion compensations, after the step of the feedback signal value of biasing tracking PT module, also comprises:
Abandon under the dispersion point of the setpoint distance that departs from the actual dispersion value feedback signal value of described PT module.
3. method according to claim 2 is characterized in that, under the described dispersion point of abandoning the setting quantity that departs from the actual dispersion value, the step of the feedback signal value of described PT module comprises:
Dispersion point with minimum value in the described TDC dispersion values is the center, about respectively get 4 continuous dispersion points, obtain 9 continuous dispersion points;
Obtain the feedback signal value of described PT module under described 9 dispersion points, abandon the feedback signal value of described PT module under other dispersion point.
4. according to claim 1,2 or 3 described methods, it is characterized in that described feedback signal value is carried out curve fitting, and the step of obtaining the chromatic dispersion adjusted value comprises:
More described feedback signal value finds minimum point as the center;
About this center, respectively get first point of setting quantity and carry out the binomial match, obtain first matched curve;
Minimum point with described first matched curve is the center, respectively gets second point of setting quantity and carry out Gauss curve fitting about this center, obtains second matched curve;
According to described second matched curve, obtain described chromatic dispersion adjusted value.
5. method according to claim 1 is characterized in that, described obtaining at different dispersion compensations adjusted under the TDC dispersion values, and the step that the feedback signal value of PT module is followed the tracks of in biasing comprises:
With 100 ps/nm is step-length, and the dispersion values in the whole threshold range is adjusted;
Adjust point at each and carry out the collection of the feedback signal value of described PT module.
6. method according to claim 5 is characterized in that, adjusts under the TDC dispersion values described obtaining at different dispersion compensations, after the step of the feedback signal value of biasing tracking PT module, also comprises:
1 millisecond at every interval is read described feedback signal value 1000 times from Serial Peripheral Interface SPI;
Described 1000 feedback signal values that read are done on average, obtained feedback signal value after average as final feedback signal value.
7. according to each described method among claim 1-3, the 5-6, it is characterized in that described method is applied to the 100G optical transmission of polarization tracking.
8. a dispersion compensation device is characterized in that, comprises main control module and dispersion compensation adjustment TDC module, wherein,
Described main control module comprises:
The feedback signal module is used to obtain under different TDC dispersion values, and the feedback signal value of PT module is followed the tracks of in biasing;
Curve fitting module is used for described feedback signal value is carried out curve fitting, and obtains the chromatic dispersion adjusted value, and sends to described TDC module;
Described TDC module is used for according to described chromatic dispersion adjusted value described TDC dispersion values being carried out the chromatic dispersion adjustment.
9. device according to claim 8 is characterized in that, described main control module also comprises:
Abandon module, be used for obtaining under different dispersion compensations adjustment TDC dispersion values in described feedback signal module, biasing is followed the tracks of after the feedback signal value of PT module, abandons under the dispersion point of the setpoint distance that departs from the actual dispersion value feedback signal value of described PT module.
10. device according to claim 9, it is characterized in that, the described module of abandoning is used for obtaining under different dispersion compensations adjustment TDC dispersion values in described feedback signal module, biasing is followed the tracks of after the feedback signal value of PT module, dispersion point with minimum value in the described TDC dispersion values is the center, about respectively get 4 continuous dispersion points, obtain 9 continuous dispersion points; Obtain the feedback signal value of described PT module under described 9 dispersion points, abandon the feedback signal value of described PT module under other dispersion point.
11. according to Claim 8,9 or 10 described devices, it is characterized in that described curve fitting module comprises:
First fitting module is used for more described feedback signal value, finds minimum point as the center; About this center, respectively get first point of setting quantity and carry out the binomial match, obtain first matched curve;
Second fitting module, the minimum point that is used for described first matched curve is the center, respectively gets second point of setting quantity and carry out Gauss curve fitting about this center, obtains second matched curve;
Obtain sending module, be used for obtaining described chromatic dispersion adjusted value, and send to described TDC module according to described second matched curve.
12. device according to claim 8 is characterized in that, it is step-length that described feedback signal module is used for 100 ps/nm, and the dispersion values in the whole threshold range is adjusted; Adjust point at each and carry out the collection of the feedback signal value of described PT module.
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