CN107979411B - Method and device for monitoring optical fiber link - Google Patents
Method and device for monitoring optical fiber link Download PDFInfo
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- CN107979411B CN107979411B CN201610921819.0A CN201610921819A CN107979411B CN 107979411 B CN107979411 B CN 107979411B CN 201610921819 A CN201610921819 A CN 201610921819A CN 107979411 B CN107979411 B CN 107979411B
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Abstract
The invention discloses a method and a device for monitoring an optical fiber link, which comprise the following steps: generating a pseudo-random sequence with adjustable chip width and chip rate for monitoring the optical fiber link as a detection sequence according to the length and the state of the optical fiber link; combining the detection sequence and the service information into a composite frame according to service flow, and transmitting the composite frame in an optical fiber; and receiving the scattered signal and/or the reflected signal of the detection sequence in the optical fiber, and performing sampling and digital low-pass filtering on the scattered signal and/or the reflected signal to obtain optical fiber link information for monitoring the optical fiber link. The invention realizes the purpose of monitoring the performance of the optical fiber link on line in real time based on the mode of multiplexing the composite frame by the detection sequence and the service signal, improves the measurement performance and reduces the maintenance cost of the optical fiber link of the optical network.
Description
Technical Field
The present invention relates to the field of optical fiber communication technologies, and in particular, to a method and an apparatus for monitoring an optical fiber link.
Background
With the continuous development of optical fiber communication technology and the massive laying of optical fibers, optical fiber communication becomes an important mode of modern information transmission, provides huge transmission bandwidth for communication networks, and becomes the most important transmission means of information networks. The new generation of optical transport networks is developing towards "high speed, large capacity, convergence, intelligence", and in the high speed and large capacity, 100G is already in commercial scale, and 400G is also accelerating standardization and starting to be in commercial use. There is an increasing interest in the rapid, stable and reliable transmission of information. In this case, if the optical fiber line of the optical transmission network is interrupted by an unexpected fault, huge social impact and immeasurable economic loss will be caused. Practical working experience has shown that line faults in fiber optic communications are more prominent than equipment faults.
An Optical Time-Domain Reflectometer (OTDR) is the most common Optical fiber line measuring instrument, and detects the attenuation and disconnection point of an Optical fiber line by detecting the backward rayleigh scattered light of a measured Optical fiber. Conventional OTDRs inject optical pulses into an optical fiber as a probe signal. When the optical pulse propagates along the optical fiber, the backward scattering part of rayleigh scattering at each position continuously returns to the incident end of the optical fiber, when the optical signal encounters a fracture in the light, fresnel reflection is generated, and the backward reflection light also returns to the incident end of the optical fiber. The loss characteristics, the length, the breakpoint fault position and the like of the optical fiber can be quantitatively measured by detecting the size and the arrival time of the back scattering light at the input end through a proper optical circulator and a photoelectric detector with high-speed response.
The traditional optical fiber line maintenance mode is that after an optical fiber line is in an obstacle, a machine room attendant determines a fault line section according to equipment alarm information, then an optical time domain reflectometer is used for measuring in the section to determine a fault point, and finally a line emergency repair worker is informed to rush to a specific site for emergency repair. The traditional optical fiber line maintenance method is excessively dependent on manpower, has low efficiency and is difficult to ensure the smoothness of a high-speed, broadband and large-capacity optical transmission network. Therefore, a technical means is urgently needed to realize real-time online monitoring of the optical fiber line and timely discover and forecast the hidden optical fiber trouble so as to improve the operation quality of the optical transmission network and reduce the complexity and cost of maintaining the optical fiber link.
Disclosure of Invention
The invention aims to provide a method and a device for monitoring an optical fiber link, which are used for solving the problem of high maintenance cost of the optical fiber link in the prior art.
In order to solve the above technical problem, in one aspect, the present invention provides a method for monitoring an optical fiber link, including:
generating a pseudo-random sequence with adjustable chip width and chip rate for monitoring the optical fiber link as a detection sequence according to the length and the state of the optical fiber link;
combining the detection sequence and the service information into a composite frame according to the service flow, and transmitting the composite frame in an optical fiber;
and receiving the scattered signal and/or the reflected signal of the detection sequence in the optical fiber, and performing sampling and digital low-pass filtering on the scattered signal and/or the reflected signal to obtain optical fiber link information for monitoring the optical fiber link.
Further, according to the obtained optical fiber link information, a detection sequence for monitoring the optical fiber link is regenerated by adjusting the chip width and the chip rate, and the passband bandwidth parameter for digital low-pass filtering is adjusted to continue the optical fiber link monitoring.
Further, regenerating a detection sequence for monitoring the optical fiber link, and adjusting a passband bandwidth parameter for performing digital low-pass filtering specifically include:
when an abnormal event exists in the optical fiber link according to the optical fiber link information, selecting a detection sequence with smaller chip width for monitoring the optical fiber link and improving the passband bandwidth parameter on the premise of keeping the measurement time unchanged;
when detecting that no abnormal event exists in the optical fiber link according to the optical fiber link information, keeping the current detection sequence and the passband bandwidth parameter unchanged; or, on the premise of unchanging the measurement time, selecting a detection sequence with a larger chip width for optical fiber link monitoring and reducing the passband bandwidth parameter.
Further, the structure of the composite frame is dynamically adjusted according to the traffic of the service information, and the specific adjustment rule is as follows:
1) when L issWhen the length is equal to 0, the composite frame is formed by the length LPThe detection sequence of (1);
2) when 0 < Ls≤LthThen, the composite frame is composed of length LsHas a service information and length of LPThe detection sequence of (1);
3) when L isth＜LsThen, the composite frame is composed of length LsThe service information of (2) is formed;
wherein L issBit length, L, required to transmit information in all of the traffic information queues in two transmission intervalsthIs a traffic information length threshold.
Further, the ratio of the sounding sequence to the service information in each composite frame is fixed.
Further, when the detection sequence is not included in the composite frame, no sampling is performed; and when the detection sequence is included in the composite frame, sampling at the moment that the detection sequence of each composite frame starts to be injected into the optical fiber, wherein the sampling time length is the time length of the detection sequence.
Further, acquiring the optical fiber link information, and monitoring the optical fiber link, specifically including:
convolving the filtered data with a local reference sequence to obtain a cross-correlation sequence;
obtaining effective data for carrying out optical fiber link measurement in the cross-correlation sequence;
and detecting abnormal events according to the effective data.
Further, before the convolution is performed on the local reference sequence, the method further includes:
performing polarity conversion on the local reference sequence, wherein unipolar polarity is converted into bipolar polarity;
expanding the local reference sequence after polarity conversion, and matching the local reference sequence with sampled data;
and reversing the expanded local reference sequence.
Further, in the cross-correlation sequence, obtaining effective data for performing optical fiber link measurement specifically includes:
taking a data sequence between the fiber backward Rayleigh scattering response ending position and a third peak value after the second peak value in the cross-correlation sequence, and averaging the data sequence to obtain Nb；
Correlating each data in the cross-correlation sequence with NbObtaining a difference to obtain a cross-correlation sequence for eliminating the influence of the extinction ratio;
and selecting data from a second peak value to a third peak value from the cross-correlation sequence without the influence of the extinction ratio as effective data of the optical fiber link measurement.
Further, before convolving the filtered data with the local reference sequence, the method further includes:
accumulating the data after each filtering and the data stored after the previous filtering, storing the result, and averaging the data of the memory when the filtering times reach a preset threshold value;
in the subsequent step, the averaged data is convolved with the local reference sequence.
In another aspect, the present invention further provides a monitoring apparatus for an optical fiber link, including:
the detection sequence generator is used for generating a pseudo-random sequence with adjustable chip width and chip rate for monitoring the optical fiber link as a detection sequence according to the length and the state of the optical fiber link sent by the controller;
the buffer is used for buffering the service information;
a composite frame generator for combining the probe sequence and the service information into a composite frame according to the service flow;
the laser is used for converting the composite frame into an optical signal and then sending the optical signal to an optical fiber for transmission;
the photoelectric detector is used for receiving the scattered signal and/or the reflected signal of the detection sequence in the optical fiber and performing photoelectric conversion;
the sampler is used for sampling the output signal of the photoelectric detector according to a sampling instruction of the controller;
the filter is used for carrying out digital low-pass filtering according to the passband bandwidth parameter sent by the controller;
the processor is used for acquiring optical fiber link information according to the filtered data;
and the controller is used for monitoring the optical fiber link according to the optical fiber link information.
Further, the controller is further configured to:
according to the obtained optical fiber link information, regenerating detection sequence parameters for monitoring the optical fiber link by adjusting the chip width and the chip rate, and sending the detection sequence parameters to a detection sequence generator; and the number of the first and second groups,
and adjusting the passband bandwidth parameters and sending the passband bandwidth parameters to the filter.
Further, the controller is further configured to:
when an abnormal event exists in the optical fiber link according to the optical fiber link information, on the premise that the measurement time is not changed, the chip width of the detection sequence is reduced, the number of chips in the detection sequence is increased, and the passband bandwidth parameter is increased;
when the optical fiber link is detected to have no abnormal event according to the optical fiber link information, keeping the current detection sequence and the passband bandwidth parameter unchanged; or, on the premise that the measurement time is not changed, the chip width of the detection sequence is increased, and the passband bandwidth parameter is reduced.
Further, the structure of the composite frame is dynamically adjusted according to the traffic of the service information, and the specific adjustment rule is as follows:
1) when L issWhen the length is equal to 0, the composite frame is formed by the length LPThe detection sequence of (1);
2) when 0 < Ls≤LthThen, the composite frame is composed of length LsHas a service information and length of LPThe detection sequence of (1);
3) when L isth＜LsThen, the composite frame is composed of length LsThe service information of (2) is formed;
wherein L issBit length, L, required to transmit information in the entire service information queue within two transmission intervalsthIs a traffic information length threshold.
Further, the ratio of the sounding sequence to the service information in each composite frame is fixed.
Further, the processor is further configured to:
convolving the filtered data with a local reference sequence to obtain a cross-correlation sequence;
obtaining effective data for carrying out optical fiber link measurement in the cross-correlation sequence;
and detecting abnormal events according to the effective data.
Further, the processor is further configured to:
before the convolution of the local reference sequence, the local reference sequence is subjected to polarity conversion, and unipolar polarity is converted into bipolar polarity;
expanding the local reference sequence after polarity conversion, and matching the local reference sequence with sampled data;
and reversing the expanded local reference sequence.
Further, the processor is further configured to:
taking the data sequence between the fiber backward Rayleigh scattering response ending to the third peak value after the second peak value in the cross-correlation sequence, and averaging the data sequence to obtain an average value Nb；
Correlating each data in the cross-correlation sequence with NbCalculating difference, and eliminating the influence caused by the extinction ratio of the laser in the cross-correlation sequence;
and selecting data from a second peak value to a third peak value from the cross-correlation sequence without the influence of the extinction ratio as effective data of the optical fiber link measurement.
Further, the processor is further configured to:
before the filtered data and the local reference sequence are convolved, accumulating the filtered data of each time and the data stored after the previous filtering, storing the result, and averaging the data of a memory when the filtering times reach a preset threshold value;
in the subsequent step, the averaged data is convolved with the local reference sequence.
Further, the controller is further configured to:
when the detection sequence is not included in the composite frame, no sampling instruction is sent;
when the sounding sequence is included within the composite frame, then the sampling instructions include: sampling is carried out at the moment when the detection sequence of each composite frame starts to be injected into the optical fiber, and the sampling time length is the time length of the detection sequence.
The invention has the following beneficial effects:
the invention realizes the purpose of monitoring the performance of the optical fiber link on line in real time based on the mode of multiplexing the composite frame by the detection sequence and the service signal, improves the measurement performance and reduces the maintenance cost of the optical fiber link of the optical network.
Drawings
Fig. 1 is a schematic structural diagram of a monitoring apparatus for an optical fiber link according to an embodiment of the present invention;
FIG. 2a is a schematic structural diagram of a variable composite frame according to an embodiment of the present invention;
FIG. 2b is a diagram illustrating a structure of another variable composite frame according to an embodiment of the present invention;
FIG. 2c is a schematic diagram of a structure of another variable composite frame according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a method for monitoring an optical fiber link according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail below with reference to the drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
Example one
As shown in fig. 1, the present embodiment relates to a monitoring apparatus for an optical fiber link, which includes a controller 207, a probe sequence generator 206, a composite frame generator 201, a buffer 200, a laser 202, a photodetector 208, a sampler 209, a filter 210, and a processor 211, wherein:
and the controller 207 is used for controlling the coordination work among all the modules and is connected with the detection sequence generator 206, the composite frame generator 201, the sampler 209, the filter 210, the buffer 200 and the processor 211. The controller 207 functions are specifically:
according to the optical fiber link information reported by the processor 211, the parameters of the probe sequence measured this time and the passband bandwidth parameters of the filter 210 are determined, and the probe sequence parameters are sent to the probe sequence generator 206 and the processor 211, and the set passband bandwidth parameters are sent to the filter 210. The optical fiber link information comprises the length and the state of the optical fiber link, wherein the state comprises the existence of an abnormal event in the link and the nonexistence of the abnormal event in the link.
The structure of the composite frame is determined according to the data length calculation of the service information buffer queue (buffer 200). The structure of the composite frame may be a fixed composite frame structure or a variable composite frame structure. When the composite frame structure is a fixed composite frame structure, periodically sending composite frame information to a composite frame generator, wherein the proportion of the detection sequence and the service information in the composite frame is fixed, namely: each composite frame is identical in structure. When the composite frame structure is variable, the composite frame structure may be any one of those shown in fig. 2 a-c, that is, if there is no service information in the buffer queue, there is only a probe sequence in the composite frame; if the bit length required for sending the service information in the cache queue is less than the threshold value, the composite frame has the service information; and if the bit length required for sending the service information in the cache queue is greater than the threshold value, only the service information is in the composite frame.
The controller 207 is further configured to determine a start time of sampling by the sampler 209 based on the composite frame structure information. If there is no sounding sequence in the composite frame, no sampling instruction is sent to the sampler 209; if there is a sounding sequence in the composite frame, a sampling instruction is sent to the sampler 209, where the sampling instruction includes: sampling is carried out at the moment when the detection sequence of each composite frame starts to be injected into the optical fiber, and the sampling time length is the time length of the detection sequence.
And the buffer 200 is respectively connected to the controller 207 and the composite frame generator 201, and is configured to receive the service information and buffer the service information, and report the length of the service information to the controller 207 whenever the controller 207 polls the length of the service information.
The detection sequence generator 206 is connected to the controller 207 and the composite frame generator 201, respectively, and is configured to generate a corresponding pseudo-random sequence as a detection sequence for optical fiber link detection according to a detection sequence parameter given by the controller 207, and send the generated detection sequence to the composite frame generator 201 connected thereto. Wherein the detection sequence generator 206 obtains different detection sequences by adjusting the chip width and chip rate of the pseudo-random sequence.
And a composite frame generator 201, connected to the buffer 200, the probe sequence generator 206, the controller 207 and the laser 202, respectively, for combining the service signal and the probe sequence into a composite frame according to the composite frame structure information sent from the controller 207, and sending the composite frame to the laser 207.
A laser 202 (including a driving module) connected to the composite frame generator 201, for performing photoelectric conversion on the electrical signal sent from the composite frame generator 201, and sending the optical signal to the optical fiber 204; the OSC service information receiver 205 receives the service information normally.
And the photoelectric detector 208 is respectively connected with the controller 207 and the sampler 209, backward Rayleigh scattering signals and reflection signals of the optical fibers enter the photoelectric detector 208 through the optical circulator 203, and the photoelectric detector 208 receives the backward Rayleigh scattering signals and the reflection signals of the optical fibers, performs photoelectric conversion and amplifies electric signals.
And the sampler 209 is respectively connected with the photodetector 208, the controller 207 and the filter 210, and is configured to convert the analog signal output by the photodetector 208 into a digital signal, and start sampling at a starting time after receiving a sampling instruction from the controller 210, where each sampling time is a time length of the detection sequence.
A filter 210, coupled to the sampler 209, the controller 207 and the processor 211, respectively, for low pass filtering the sampled data. The passband bandwidth of the filter 210 is adjusted according to the passband bandwidth parameters given by the controller 210. For example, in the large dynamic monitoring range mode, the passband bandwidth is 1 MHz; in the high spatial resolution monitoring mode, the passband bandwidth is 50 MHz.
And the processor 211 is connected to the controller 207 and the filter 210, respectively, and is configured to implement data processing procedures such as data averaging, correlation calculation, event detection, and the like, and report a data processing result. For example, the processor 210 first averages the filtered data for 100,000 times, then generates a local reference sequence for cross-correlation with the averaged data according to the probe sequence information sent from the controller 207, and convolves the two to complete the correlation calculation. And finally, carrying out event detection on the related calculated data, and reporting the optical fiber link information.
The controller 207 performs abnormal event detection on the link information reported by the processor 211, and when the abnormal event does not exist in the link information reported by the processor 211, the controller 207 adjusts the detection sequence to adopt a 10-level m sequence, and the passband bandwidth parameter of the filter is set to be 1 MHz; and monitoring the optical fiber link again. If the reported link information has an abnormal event, the detection sequence adopts a 16-level m sequence, and the passband bandwidth parameter of the filter is set to be 50 MHz; and monitoring the optical fiber link again.
As shown in fig. 3, this embodiment further relates to a method for monitoring an Optical fiber link by using the monitoring apparatus, where the OTDR performs online monitoring of the Optical fiber link by using an OSC (Optical Supervisory Channel) service Channel, and the composite frame structure may be dynamically adjusted according to the traffic information flow, and the specific steps are as follows:
generating a pseudo-random sequence with adjustable chip width and chip rate according to the length and the state of the optical fiber link, and using the pseudo-random sequence as a detection sequence for monitoring the optical fiber link.
In this embodiment, an m-sequence is used as the detection sequence of the OTDR, and the m-sequence period time length NTc is the product of the number N of chips in one period of the m-sequence and the m-sequence chip width Tc. The OSC traffic channel rate is 125Mbps, each bit width is 8ns, so each chip width can only be an integer multiple of 8 ns. The number N of chips of the m sequence can only be 2n-1, wherein n is a positive integer greater than 2.
According to the basic principle of the correlation measurement, if the information of the whole optical fiber link is completely obtained, the duration NTc of one period of the m-sequence is at least longer than the duration of the backward rayleigh scattering impact response of the optical fiber. For the duration of the backward Rayleigh scattering impulse response of the fiber, it can be L/vgPerforming a calculation, wherein L is a designed monitoring length of the optical fiber link, vgIs the group velocity of light propagation, and is about 2X 108m/s in terms of typical refractive index; in this embodiment, the optical fiber link with at least 100km length is monitored, and the monitored length is designedWhich is 120km, the duration NTc of one period of the m-sequence is at least 1.2 ms.
Under the condition that the above conditions are met, theoretically, any m sequence can be selected as the detection sequence, but the measurement time, the dynamic range and the spatial resolution are in a mutual constraint relation. In the embodiment, under the condition that the minimum measurement time is not changed, the large dynamic range monitoring and the high spatial resolution monitoring are realized by changing the chip width Tc, and the performances of the large dynamic range monitoring and the high spatial resolution monitoring are considered. Comprehensively considering, a 10-level m sequence (N is 1,023) is selected as a detection sequence, and the chip width is 1,536ns as the detection sequence in the large dynamic range mode; a 16-level m-sequence (N65,535) is selected as the detection sequence, a chip width of 24ns is the detection sequence in the high spatial resolution mode, and the single measurement time of both is 4.72 ms.
The selection of the detection sequence is determined according to the link information of the last measurement, and if no abnormal reflection point (abnormal event) exists, a large dynamic range mode is selected to monitor all information of the whole optical fiber; and if the abnormal reflection point exists, selecting a high spatial resolution mode to accurately position the abnormal reflection point. The first measurement uses a large dynamic range mode.
If a larger optical fiber link length needs to be monitored, increasing the chip width of a pseudo-random sequence (detection sequence) and reducing the chip rate of the pseudo-random sequence so as to improve the dynamic range of the monitoring system; if a certain abnormal point needs to be accurately positioned, the chip width of the pseudo-random sequence needs to be reduced, and the chip rate of the pseudo-random sequence needs to be increased, so that the spatial resolution of the monitoring system is improved. When the optical fiber link is measured for the first time, the monitoring system preferentially obtains a monitoring mode with a large dynamic range so as to cover the whole optical fiber link. And when in normal measurement, the chip width is flexibly and dynamically changed according to the monitoring requirement.
And step two, combining the detection sequence and the service information into a composite frame according to the service flow. The structure of the composite frame is shown in fig. 2 a-c, and the structure and length of the composite frame are determined by the flow of the current service information. The arriving OSC service information is buffered in a service information queue (buffer), and after the last composite frame is sent, the service information queue in the buffer has new service information, and the length of the service information queue reflects the current traffic information flow. The step of synthesizing a composite frame each time is as follows,
first, the bit length L required to transmit all the traffic information queues to the channel is calculateds，
Secondly, according to LsAnd the set traffic information length threshold LthAnd synthesizing a composite frame. The composite frame structure is dynamically adjusted according to the traffic of the service information:
if L issIf it is 0, it indicates that there is no service data in the service information queue of the buffer area, and there is no service information in the last time period, so there is no need to transmit service information, and only length L in the composite framePA sounding sequence of 589,824 bits (4.72 ms in length) as shown in fig. 2 a.
If 0 < Ls≤LthThen, the length is L in the composite framesAll service information and length L ofPIs a sounding sequence of 589,824 bits, as shown in fig. 2 b.
If L isth＜LsIf so, it indicates that the traffic information flow is large, and at this time, the composite frame no longer includes the probe sequence, but only has a length of LsAs shown in fig. 2 c.
Service information length threshold LthThe value is a fixed value, and needs to be set in advance according to the average service flow condition of the optical fiber link to be measured, in this embodiment, Lth589,824, that is, the traffic information threshold length is the same as the probe sequence length.
And converting the composite frame digital sequence into an electric pulse sequence through a pulse shaping filter.
And step three, converting the electric signal of the composite frame into an optical signal by the laser and sending the optical signal to the optical fiber. The average transmitted power of the optical signal was 3dBm and the extinction ratio was 10 dB. The OSC receiver normally receives OSC service signals, backward Rayleigh scattering occurs in the optical fiber for detection signals, and Fresnel reflection occurs at a reflection point. The backward Rayleigh scattering signal and the reflection signal of the optical fiber enter the photoelectric detector through the circulator to be subjected to photoelectric conversion.
And step four, sampling by a sampler at the moment when the detection sequence starts to be injected into the optical fiber in each composite frame, and controlling the sampler to stop sampling at the end moment of each composite frame. In the high spatial resolution mode, the chip rate of the probe sequence is about 42Mchip/s, and in the high dynamic range mode, the chip rate of the probe sequence is 6.54kchip/s, so the sampling rate is set to 125MSa/s, which is 3 times the highest chip rate. After the output signal of the photoelectric detector is sampled, the backward Rayleigh scattering signal and the reflection signal of the optical fiber are changed into digital signals from analog signals.
Step five, performing digital low-pass filtering on the adopted digital signal, wherein the bandwidth of the filter depends on the chip rate of the detection sequence, the chip rate of the detection sequence is 6.54kchip/s in a large dynamic range mode, the requirement on the spatial resolution is low, and noise is required to be filtered as much as possible, so the passband cut-off frequency of the digital low-pass filter is 1 MHz; in the high spatial resolution mode, the chip rate of the detection sequence is 42Mchip/s, the requirement on the spatial resolution is high, and therefore the passband cut-off frequency of the digital low-pass filter is 50 MHz.
And step six, repeating the step three to the step five to carry out multiple measurements, and carrying out accumulation averaging on the data after the multiple measurements. And accumulating the data after each filter and the data stored in the previous time, storing the result, and averaging the data in the memory when the actual measurement times reach 100,000 times of measurement in a preset design.
And seventhly, performing correlation calculation on the averaged data and the local reference sequence. The local reference sequence needs to be preprocessed before the correlation calculation is performed. The optical power can only be positive, so the detection optical sequence can only be unipolar, and according to the m-sequence correlation principle, if the optical fiber link information can be recovered, at least one of the detection sequence and the local correlation sequence should be a bipolar sequence. Therefore, the local reference sequence needs to be subjected to polarity conversion, namely, unipolar conversion is carried out, and the pseudo-random detection sequence generated by the pseudo-random sequence generator is S, namely, the local reference sequence is 2 xS-1.
Because the sampling rate is higher than the chip rate and each probe sequence chip corresponds to multiple sample points, the length of the local reference sequence needs to be extended to match the sampled data. In the high resolution mode, the sampling rate is 3 times the chip rate, so that the chips of each acquisition sequence correspond to 3 sampled data points. For example, if the local reference sequence length is "1-11" before being extended, then the padded reference sequence is "111-1-1-1111". I.e. the sequence length should be extended by a factor of 3 by inserting two identical values after the value in each sequence. In the large dynamic range mode, the sample rate is 192 times the chip rate, so the local reference sequence length is extended 192 times.
And reversing the expanded local reference sequence to complete local sequence preprocessing. And convolving the preprocessed local reference sequence with the averaged sampling data to obtain a convolved sequence, wherein the convolved sequence is a cross-correlation sequence of the local reference sequence and the sampling data. If using SLRepresenting the preprocessed local reference sequence, and R represents the averaged sample data sequence, the specific calculation formula of the cross-correlation sequence c (n) is as follows:
wherein, the parameters mn in the above formula are the numbers of the data.
And step eight, extracting the optical fiber link information from the mutual sequence obtained by the correlation calculation.
Since practical lasers do not have infinite extinction ratios, there is also a need to eliminate the effect of non-idealities in the extinction ratio on the dynamic range. Taking the data sequence between the end position of the fiber backward Rayleigh scattering response and the third peak value after the second peak value is taken from the cross-correlation sequence, averaging the data sequence to obtain an average value Nb. For each data and N in the correlation sequencebAnd (4) performing subtraction to eliminate the influence of the non-ideal extinction ratio on the dynamic range. And intercepting the data of the second peak to the third peak in the cross-correlation sequence as effective data of the optical fiber link measurement. And (4) carrying out event detection on the effective data by using a least square method, and analyzing and recording abnormal events. According to the sampling time and the propagation of light in the fibreAnd determining the spatial position corresponding to each sampling point by the group velocity to obtain the information data of the whole optical fiber link. In the art, there are various existing methods (for example, by a least square method) for analyzing an abnormal event of an optical fiber link, and the technical solution of the present invention also focuses on analyzing an abnormal event of an optical fiber link, and therefore, the present embodiment does not describe details about analyzing an abnormal event of an optical fiber link.
And step nine, feeding back the optical fiber link information to the controller, reporting the measurement result to an upper layer by the controller, and carrying out the next measurement according to the feedback information. If no abnormal event exists in the optical fiber link, the optical fiber link is monitored continuously in a large dynamic range mode; if the abnormal event is found, the optical fiber link is continuously monitored by adopting a high spatial resolution mode, so that the spatial resolution is improved, and the position of the abnormal event is accurately positioned.
Example two
The embodiment has the same structure as the first embodiment, and the main difference lies in the step two in the implementation method, and the other steps are the same as the first embodiment, so the embodiment only describes the step two, specifically as follows:
the OSC traffic signal and the pseudo random sounding signal are combined into a fixed length composite frame structure. The arriving OSC service information is buffered in the service information queue, and after the last composite frame is sent, the synthesizer reads the fixed length 589,824 (L) in the service information buffer queue each times) And the service information of the bit is put at the head of the composite frame. And if the information length in the service information queue is less than 589,824 bits, expanding the service information in the composite frame to a fixed length. A sounding sequence of length 589,824 bits is added at the end of the composite frame. Thus, in the composite frame, the time length of the service information is the same as that of the sounding information, and is about 4.72 ms.
The device and the method for monitoring the optical fiber performance adopt the pseudo-random sequence as a detection signal, and the detection signal and a service signal realize the online monitoring of an optical fiber link through a composite frame structure multiplexing channel. And calculating backward Rayleigh scattering or reflecting signals of the optical fiber link through cross-correlation with a local reference sequence to obtain link information. According to the condition of the optical fiber link, the pseudo-random sequence is variable, so that the dynamic range and the spatial resolution are considered simultaneously, the measurement performance is improved, and the maintenance cost of the optical fiber link of the optical network is reduced. The service signal is transmitted through the sub-frame under the composite frame, the composite frame dynamically adjusts the service signal length according to the traffic condition of the service signal, the bandwidth resource is efficiently utilized, and the normal transmission of the service signal is ensured.
EXAMPLE III
The embodiment of the invention relates to a program for realizing a monitoring function of an optical fiber link, which comprises the following procedures:
generating a pseudo-random sequence with adjustable chip width and chip rate for monitoring the optical fiber link as a detection sequence according to the length and the state of the optical fiber link;
combining the detection sequence and the service information into a composite frame according to service flow, and transmitting the composite frame in an optical fiber;
and receiving the scattered signal and/or the reflected signal of the detection sequence in the optical fiber, and performing sampling and digital low-pass filtering on the scattered signal and/or the reflected signal to obtain optical fiber link information for monitoring the optical fiber link.
And regenerating a detection sequence for monitoring the optical fiber link by adjusting the chip width and the chip rate according to the acquired optical fiber link information, and adjusting the passband bandwidth parameter for carrying out digital low-pass filtering to continue monitoring the optical fiber link.
The regenerating of the probe sequence for monitoring the optical fiber link and the adjusting of the passband bandwidth parameter for performing the digital low-pass filtering specifically include:
when an abnormal event exists in the optical fiber link according to the optical fiber link information, selecting a detection sequence with smaller chip width for monitoring the optical fiber link and improving the passband bandwidth parameter on the premise of keeping the measurement time unchanged;
when detecting that no abnormal event exists in the optical fiber link according to the optical fiber link information, keeping the current detection sequence and the passband bandwidth parameter unchanged; or, on the premise of unchanging the measurement time, selecting a detection sequence with a larger chip width for optical fiber link monitoring and reducing the passband bandwidth parameter.
The proportion of the detection sequence to the service information in each composite frame is fixed; or the structure of the composite frame is dynamically adjusted according to the traffic of the service information, and the specific adjustment rule is as follows:
1) when L issWhen the length is equal to 0, the composite frame is formed by the length LPThe detection sequence of (1);
2) when 0 < Ls≤LthThen, the composite frame is composed of length LsHas a service information and length of LPThe detection sequence of (1);
3) when L isth＜LsThen, the composite frame is composed of length LsThe service information of (2) is formed;
wherein L issBit length, L, required to transmit information in all of the traffic information queues in two transmission intervalsthIs a traffic information length threshold.
When the detection sequence is not included in the composite frame, sampling is not performed; and when the detection sequence is included in the composite frame, sampling at the moment that the detection sequence of each composite frame starts to be injected into the optical fiber, wherein the sampling time length is the time length of the detection sequence.
The above obtaining the optical fiber link information and monitoring the optical fiber link specifically includes:
convolving the filtered data with a local reference sequence to obtain a cross-correlation sequence;
obtaining effective data for carrying out optical fiber link measurement in the cross-correlation sequence;
and detecting abnormal events according to the effective data.
Before the convolution of the local reference sequence, the method further includes:
performing polarity conversion on the local reference sequence, wherein unipolar polarity is converted into bipolar polarity;
expanding the local reference sequence after polarity conversion, and matching the local reference sequence with sampled data;
and reversing the expanded local reference sequence.
The obtaining of the effective data for performing the optical fiber link measurement in the cross-correlation sequence specifically includes:
taking a data sequence between the end position of the backward Rayleigh scattering response of the optical fiber after the second peak value in the cross-correlation sequence and the third peak value, and averaging the data sequence to obtain an average value Nb；
Correlating each data in the cross-correlation sequence with NbObtaining a difference to obtain a cross-correlation sequence for eliminating the influence of the extinction ratio;
and selecting data from a second peak value to a third peak value from the cross-correlation sequence without the influence of the extinction ratio as effective data of the optical fiber link measurement.
Before convolving the filtered data with the local reference sequence, the method further includes:
accumulating the data after each filtering and the data stored after the previous filtering, storing the result, and averaging the data of the memory when the filtering times reach a preset threshold value;
in the subsequent step, the averaged data is convolved with the local reference sequence.
The present embodiment also relates to a storage medium for storing the above program, and the storage medium may be a computer-readable storage medium such as an optical disc, a magnetic disc, a flash disc, a memory, etc., and the present embodiment will not be described in detail.
It will be understood by those skilled in the art that all or part of the steps of the above methods may be implemented by instructing the relevant hardware through a program, and the program may be stored in a computer readable storage medium, such as a read-only memory, a magnetic or optical disk, and the like. Alternatively, all or part of the steps of the above embodiments may be implemented using one or more integrated circuits. Accordingly, each module/unit in the above embodiments may be implemented in the form of hardware, and may also be implemented in the form of a software functional module. The present invention is not limited to any specific form of combination of hardware and software.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, and the scope of the invention should not be limited to the embodiments described above.
Claims (18)
1. A method for monitoring an optical fiber link, comprising:
generating a pseudo-random sequence with adjustable chip width and chip rate for monitoring the optical fiber link as a detection sequence according to the length and the state of the optical fiber link;
combining the detection sequence and the service information into a composite frame according to service flow, and transmitting the composite frame in an optical fiber;
receiving a scattering signal and/or a reflection signal of the detection sequence in an optical fiber, and performing sampling and digital low-pass filtering on the scattering signal and/or the reflection signal to obtain optical fiber link information for monitoring the optical fiber link;
and regenerating a detection sequence for monitoring the optical fiber link by adjusting the chip width and the chip rate according to the acquired optical fiber link information, and adjusting the passband bandwidth parameter for carrying out digital low-pass filtering to continue monitoring the optical fiber link.
2. The method according to claim 1, wherein regenerating the probe sequence for monitoring the optical fiber link and adjusting the passband bandwidth parameters for digital low pass filtering comprise:
when an abnormal event exists in the optical fiber link according to the optical fiber link information, selecting a detection sequence with smaller chip width for monitoring the optical fiber link and improving the passband bandwidth parameter on the premise of keeping the measurement time unchanged;
when detecting that no abnormal event exists in the optical fiber link according to the optical fiber link information, keeping the current detection sequence and the passband bandwidth parameter unchanged; or, on the premise of unchanging the measurement time, selecting a detection sequence with a larger chip width for monitoring the optical fiber link and reducing the passband bandwidth parameter.
3. The method for monitoring an optical fiber link according to claim 1 or 2, wherein the structure of the composite frame is dynamically adjusted according to the traffic of the service information, and the specific adjustment rule is as follows:
1) when L issWhen the length is equal to 0, the composite frame is formed by the length LPThe detection sequence of (1);
2) when 0 < Ls≤LthThen, the composite frame is composed of length LsHas a service information and length of LPThe detection sequence of (1);
3) when L isth＜LsThen, the composite frame is composed of length LsThe service information of (2) is formed;
wherein L issBit length, L, required to transmit information in all of the traffic information queues in two transmission intervalsthIs a traffic information length threshold.
4. The method for monitoring an optical fiber link according to claim 1 or 2, wherein the ratio of the probe sequence to the traffic information in each of the composite frames is constant.
5. The method of claim 1, wherein when the probe sequence is not included in the composite frame, no sampling is performed; and when the detection sequence is included in the composite frame, sampling at the moment that the detection sequence of each composite frame starts to be injected into the optical fiber, wherein the sampling time length is the time length of the detection sequence.
6. The method for monitoring an optical fiber link according to claim 1, wherein the acquiring of the optical fiber link information to perform the optical fiber link monitoring specifically includes:
convolving the filtered data with a local reference sequence to obtain a cross-correlation sequence;
obtaining effective data for carrying out optical fiber link measurement in the cross-correlation sequence;
and detecting abnormal events according to the effective data.
7. The method for monitoring an optical fiber link according to claim 6, wherein before the convolving the local reference sequence, the method further comprises:
performing polarity conversion on the local reference sequence, wherein unipolar polarity is converted into bipolar polarity;
expanding the local reference sequence after polarity conversion, and matching the local reference sequence with sampled data;
and reversing the expanded local reference sequence.
8. The method for monitoring an optical fiber link according to claim 6, wherein the obtaining valid data for performing the optical fiber link measurement in the cross-correlation sequence specifically includes:
taking a data sequence between the fiber backward Rayleigh scattering response ending position and a third peak value after the second peak value in the cross-correlation sequence, and averaging the data sequence to obtain Nb；
Correlating each data in the cross-correlation sequence with NbObtaining a difference to obtain a cross-correlation sequence for eliminating the influence of the extinction ratio;
and selecting data from a second peak value to a third peak value from the cross-correlation sequence without the influence of the extinction ratio as effective data of the optical fiber link measurement.
9. The method of claim 6, wherein prior to convolving the filtered data with the local reference sequence, further comprising:
accumulating the data after each filtering and the data stored after the previous filtering, storing the result, and averaging the data in the memory when the filtering times reach a preset threshold value;
in the subsequent step, the averaged data is convolved with the local reference sequence.
10. An optical fiber link monitoring device, comprising:
the detection sequence generator is used for generating a pseudo-random sequence with adjustable chip width and chip rate for monitoring the optical fiber link as a detection sequence according to the length and the state of the optical fiber link sent by the controller;
the buffer is used for buffering the service information;
a composite frame generator for combining the probe sequence and the service information into a composite frame according to the service flow;
the laser is used for converting the composite frame into an optical signal and then sending the optical signal to an optical fiber for transmission;
the photoelectric detector is used for receiving the scattered signal and/or the reflected signal of the detection sequence in the optical fiber and performing photoelectric conversion;
the sampler is used for sampling the output signal of the photoelectric detector according to a sampling instruction of the controller;
the filter is used for carrying out digital low-pass filtering according to the passband bandwidth parameter sent by the controller;
the processor is used for acquiring optical fiber link information according to the filtered data;
the controller is used for monitoring the optical fiber link according to the optical fiber link information;
the controller is further configured to:
according to the obtained optical fiber link information, regenerating detection sequence parameters for monitoring the optical fiber link by adjusting the chip width and the chip rate, and sending the detection sequence parameters to a detection sequence generator; and the number of the first and second groups,
and adjusting the passband bandwidth parameters and sending the parameters to the filter.
11. The apparatus for monitoring an optical fiber link of claim 10, wherein the controller is further configured to:
when an abnormal event exists in the optical fiber link according to the optical fiber link information, on the premise that the measurement time is not changed, the chip width of the detection sequence is adjusted to be small, and the passband bandwidth parameter is increased;
when the optical fiber link is detected to have no abnormal event according to the optical fiber link information, keeping the current detection sequence and the passband bandwidth parameter unchanged; or, on the premise that the measurement time is not changed, the chip width of the detection sequence is increased, and the passband bandwidth parameter is reduced.
12. The apparatus for monitoring an optical fiber link according to claim 10 or 11, wherein the structure of the composite frame is dynamically adjusted according to the traffic of the service information, and the specific adjustment rule is as follows:
1) when L issWhen the length is equal to 0, the composite frame is formed by the length LPThe detection sequence of (1);
2) when 0 < Ls≤LthThen, the composite frame is composed of length LsHas a service information and length of LPThe detection sequence of (1);
3) when L isth＜LsThen, the composite frame is composed of length LsThe service information of (2) is formed;
wherein L issBit length, L, required to transmit information in all of the traffic information queues in two transmission intervalsthIs a traffic information length threshold.
13. An apparatus for monitoring an optical fiber link according to claim 10 or 11, wherein the ratio of probe sequence to traffic information in each of said composite frames is fixed.
14. The apparatus for monitoring an optical fiber link of claim 10, wherein the processor is further configured to:
convolving the filtered data with a local reference sequence to obtain a cross-correlation sequence;
obtaining effective data for carrying out optical fiber link measurement in the cross-correlation sequence;
and detecting abnormal events according to the effective data.
15. The apparatus for monitoring an optical fiber link of claim 14, wherein the processor is further configured to:
before the convolution is carried out on the local reference sequence, the polarity of the local reference sequence is changed, and unipolar polarity is changed into bipolar polarity;
expanding the local reference sequence after polarity conversion, and matching the local reference sequence with sampled data;
and reversing the expanded local reference sequence.
16. The apparatus for monitoring an optical fiber link of claim 14, wherein the processor is further configured to:
taking the data sequence between the fiber backward Rayleigh scattering response ending position and the third peak value after the second peak value in the cross-correlation sequence, and averaging the data sequence to obtain Nb；
Correlating each data in the cross-correlation sequence with NbObtaining a difference to obtain a cross-correlation sequence for eliminating the influence of the extinction ratio;
and selecting data from a second peak value to a third peak value from the cross-correlation sequence without the influence of the extinction ratio as effective data of the optical fiber link measurement.
17. The apparatus for monitoring an optical fiber link of claim 14, wherein the processor is further configured to:
before the filtered data and the local reference sequence are convolved, accumulating the filtered data of each time and the data stored after the previous filtering, storing the result, and averaging the data of a memory when the filtering times reach a preset threshold value;
in the subsequent step, the averaged data is convolved with the local reference sequence.
18. The apparatus for monitoring an optical fiber link of claim 10, wherein the controller is further configured to:
when the detection sequence is not included in the composite frame, no sampling instruction is sent;
when the sounding sequence is included within the composite frame, then the sampling instructions include: sampling is carried out at the moment when the detection sequence of each composite frame starts to be injected into the optical fiber, and the sampling time length is the time length of the detection sequence.
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| CN110690920A (en) * | 2019-10-25 | 2020-01-14 | 北京国信桥通信工程有限公司 | Optical fiber testing method and device |
| CN112202492B (en) * | 2020-09-01 | 2021-10-01 | 中国移动通信集团广东有限公司 | Optical cable fault positioning method and device and electronic equipment |
| CN111988090B (en) * | 2020-10-26 | 2021-01-26 | 南京信息工程大学 | Code piece mode carrier composite correlation optical coding method |
| CN112380242B (en) * | 2020-11-18 | 2022-10-28 | 中国电子科技集团公司第三十四研究所 | Optical cable test active alarm method based on OTDR |
| CN114172565B (en) * | 2021-12-03 | 2023-05-23 | 上海橙科微电子科技有限公司 | Channel quality detection method and system |
| CN114760222A (en) * | 2022-06-13 | 2022-07-15 | 北京国科天迅科技有限公司 | Link disconnection detection method and device for 100base-T1 PHY chip |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104009795A (en) * | 2013-02-25 | 2014-08-27 | 中兴通讯股份有限公司 | OTDR optical path detection device and method thereof |
| CN104350371A (en) * | 2012-05-29 | 2015-02-11 | 阿尔卡特朗讯 | Optical data transmission device using optical time domain reflectrometry |
-
2016
- 2016-10-21 CN CN201610921819.0A patent/CN107979411B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104350371A (en) * | 2012-05-29 | 2015-02-11 | 阿尔卡特朗讯 | Optical data transmission device using optical time domain reflectrometry |
| CN104009795A (en) * | 2013-02-25 | 2014-08-27 | 中兴通讯股份有限公司 | OTDR optical path detection device and method thereof |
Non-Patent Citations (1)
| Title |
|---|
| Correlation-based OTDR for in-service monitoring of 64-split TDM PON;H.K.Shim;《optics express》;20121231;1-3 * |
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