CN117692058A - OTDR non-reflection event positioning method and device based on template matching - Google Patents
OTDR non-reflection event positioning method and device based on template matching Download PDFInfo
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Abstract
The invention relates to a template matching-based OTDR non-reflection event positioning method and device, which comprises the steps of firstly, initially positioning a non-reflection event, determining the position distribution range of the non-reflection event under the condition of large pulse width, intercepting an OTDR sampling signal according to the position distribution range to obtain a search signal fragment, and determining the attenuation value of the non-reflection event; secondly, scaling a preset attenuation template based on the attenuation value, and performing sliding search in the search signal segment by utilizing the scaled attenuation template; and finally, calculating the correlation coefficient between each sampling point in the search signal segment and the corresponding point in the scaled preset attenuation template, so as to accurately position the starting point of the non-reflection event. The method and the device utilize the reference template to carry out point-by-point matching on the signals near the event position, extract the whole information, improve the positioning precision, reduce the influence of local sampling noise jitter on calculation, and effectively improve the positioning precision of the non-reflection event.
Description
Technical Field
The invention relates to the technical field of optical networks, in particular to an OTDR non-reflection event positioning method and device based on template matching.
Background
With the continuous development of optical networks, the detection and maintenance of optical cables are becoming more and more important. Optical time-domain reflectometry (OTDR) is an important tool for detecting the integrity of an Optical cable, and can be used for measuring the length, transmission performance and connection attenuation of the Optical cable and detecting the fault position of an Optical cable link. In the process of testing the optical cable, the OTDR injects a pulse laser with higher power from one end of the optical cable, and receives a reflected signal through the same side. The sudden change of the fiber back-scattered signal before and after the attenuation position is used for detecting the attenuation, and the attenuation position is calculated through the flight time corresponding to the sampling point. As nondestructive testing equipment for optical fibers, the OTDR has the advantages of high dynamic range, long distance, simple testing steps and the like, and is widely applied to the field of optical fiber link detection.
At present, the technology of automatically identifying a sampling curve by using an OTDR system and an automatic identification algorithm and positioning a flange connection point, a welding abnormal point and an optical fiber damage point of an output optical fiber link has become standard configuration of all OTDR systems. However, the prior art has a major technical bottleneck, namely: in the process of positioning a non-reflection event under a large pulse width condition, especially in the process of positioning a small attenuation event under a large pulse width, the OTDR system is still difficult to stably and accurately position a signal starting point due to the fact that the signal starting point features are weak and are easily influenced by sampling noise.
Therefore, the method and the device for locating the non-reflection event of the OTDR based on the template matching can identify the signal starting point characteristics of the non-reflection event and improve the locating precision of the OTDR system on the non-reflection event under the condition of large pulse width.
Disclosure of Invention
In view of the above, the present invention provides a method and apparatus for locating an OTDR non-reflection event based on template matching, which are used to solve the technical problems of poor stability and poor accuracy of locating a signal start point caused by weak signal start point characteristics and being easily affected by sampling noise when the existing OTDR system performs position determination on a small attenuation event under a large pulse width.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides an OTDR non-reflection event positioning method based on template matching, including:
acquiring an OTDR sampling signal obtained by returning a preset pulse signal through an optical fiber link;
determining a detection position of a non-reflection event according to the OTDR sampling signal, and determining a position distribution range of the non-reflection event according to the detection position and a preset pulse signal;
intercepting the OTDR sampling signal according to the position distribution range to obtain a search signal segment, and determining the attenuation value of the non-reflection event according to the search signal segment;
scaling a preset attenuation template based on the attenuation value, and performing sliding search in the search signal segment by using the scaled preset attenuation template;
and calculating a correlation coefficient between each sampling point in the search signal segment and a corresponding point in the scaled preset attenuation template, and determining a starting point of the non-reflection event according to the correlation coefficient.
Further, determining the position distribution range of the non-reflection event according to the preset pulse signal and the detection position includes:
calculating an optical blind area according to the pulse width of the preset pulse signal and the preset sampling resolution;
and correcting the detection position of the non-reflection event according to the optical blind area to obtain the position distribution range of the non-reflection event.
Further, intercepting the OTDR sampling signal according to the position distribution range to obtain a search signal segment, including:
and intercepting the sampling signals corresponding to the start and stop points of the position distribution range in the OTDR sampling signals to obtain search signal fragments.
Further, determining an attenuation value of the non-reflection event according to the search signal segment includes:
acquiring a natural attenuation coefficient corresponding to the optical fiber link;
determining an attenuation initial value of the non-reflection event according to the search signal segment, the natural attenuation coefficient and a preset sampling resolution;
and adjusting the attenuation initial value according to a preset correction rule to obtain the attenuation value of the non-reflection event.
Further, the attenuation initial value is adjusted according to a preset correction rule to obtain the attenuation value of the non-reflection event, which comprises the following steps:
and when the attenuation initial value is within a preset minimum attenuation threshold range, taking the preset minimum attenuation threshold as the attenuation value of the non-reflection event.
Further, scaling the preset attenuation template based on the attenuation value includes:
determining the stretching coefficient of the non-reflection event blind zone according to the signal length of the preset attenuation template and the optical blind zone;
and scaling the preset attenuation template according to the attenuation value, the stretching coefficient, the natural attenuation coefficient and the preset sampling resolution.
Further, calculating a correlation coefficient between each sampling point in the search signal segment and a corresponding point in the scaled preset attenuation template includes:
based on the position of the sampling point in the search signal segment, performing sampling value adjustment on the sampling point to obtain an adjusted sampling point;
and calculating the correlation coefficient between the signal value corresponding to the adjusted sampling point in the search signal segment and the signal value corresponding to the scaled preset attenuation template.
In a second aspect, the present invention further provides a positioning device for OTDR non-reflection events based on template matching, including:
the signal acquisition module is used for acquiring an OTDR sampling signal obtained by returning a preset pulse signal through an optical fiber link;
the position range determining module is used for determining the detection position of the non-reflection event according to the OTDR sampling signal and determining the position distribution range of the non-reflection event according to the detection position and a preset pulse signal;
the attenuation value calculation module is used for intercepting the OTDR sampling signal according to the position distribution range to obtain a search signal segment, and determining the attenuation value of the non-reflection event according to the search signal segment;
the sliding search module is used for scaling a preset attenuation template based on the attenuation value, and sliding search is carried out in the search signal segment by utilizing the scaled preset attenuation template;
and the positioning module is used for calculating the correlation coefficient between each sampling point in the search signal segment and the corresponding point in the scaled preset attenuation template, and determining the starting point of the non-reflection event according to the correlation coefficient.
In a third aspect, the present invention further provides an electronic device, including a processor and a memory, where the memory stores a computer program, where the computer program, when executed by the processor, implements the method for positioning OTDR non-reflection events based on template matching according to any one of the above technical solutions.
In a fourth aspect, the present invention further provides a computer readable storage medium, configured to store a computer readable program or instructions, where the program or instructions, when executed by a processor, implement the steps in the OTDR non-reflection event positioning method based on template matching in any one of the above implementations.
The invention provides a template matching-based OTDR non-reflection event positioning method and device, which comprises the steps of firstly, initially positioning a non-reflection event, determining the position distribution range of the non-reflection event under the condition of large pulse width, intercepting an OTDR sampling signal according to the position distribution range to obtain a search signal fragment, and determining the attenuation value of the non-reflection event; secondly, scaling a preset attenuation template based on the attenuation value, and performing sliding search in the search signal segment by utilizing the scaled attenuation template; and finally, calculating the correlation coefficient between each sampling point in the search signal segment and the corresponding point in the scaled preset attenuation template, so as to accurately position the starting point of the non-reflection event. According to the method, the stretching and stretching operation is carried out on the reference attenuation template, the integral matching is carried out on the OTDR signals, the signal characteristics of small attenuation can be identified, and the positioning effect on non-reflection events is improved. Especially under the condition of large pulse width, the starting point of small attenuation is usually too weak in signal, the position point characteristics are not obvious, and the influence of sampling curve jitter is easy to influence, the method of the application utilizes the reference template to carry out point-by-point matching on the signal near the actually identified OTDR event position, and the positioning accuracy is improved, meanwhile, the influence of local sampling noise jitter on event position calculation is reduced, and the positioning accuracy of a non-reflection event under the condition of large pulse width is effectively improved.
Drawings
FIG. 1 is a flowchart of a method for locating an OTDR non-reflective event based on template matching according to one embodiment of the present invention;
FIG. 2 is a graphical illustration of the calculation of the initial values of attenuation provided by the present invention;
FIG. 3 is a schematic diagram of a decay event of a preset decay template according to the present invention;
FIG. 4 is a schematic diagram of the principle of locating the origin of a non-reflective event by matching a new template;
fig. 5 is a schematic diagram of a practical application scenario of the method provided by the present invention;
FIG. 6 is a schematic structural diagram of an embodiment of a positioning device for an OTDR non-reflection event based on template matching according to the present invention;
fig. 7 is a schematic structural diagram of an embodiment of an electronic device according to the present invention.
Detailed Description
Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and together with the description serve to explain the principles of the invention, and are not intended to limit the scope of the invention.
It is to be understood that technical terms, acronyms, and the like appearing hereinafter are prior art and those skilled in the art are able to understand their meanings based on context and are not described here too much for reasons of brevity.
In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
Prior to describing embodiments of the present invention, related terms and background art of the present application will be described.
OTDR: an OTDR (Optical Time Domain Reflectometer ) is a fiber optic instrument for performing feature analysis, troubleshooting, and maintenance of an optical communication network, and comprises a laser diode light source, an avalanche diode, and a highly accurate timing circuit (or time base). The laser emits a pulse of light at a specific wavelength that propagates along the fiber under test, and as the pulse moves downward, light transmitted in the fiber will reflect/refract or scatter back along the fiber to the photodetector in the OTDR. By detecting the intensity of this returned light and the time it takes to return to the detector, the loss value (insertion and reflection), type and location of an event in the fiber optic link can be known.
Reflective events and non-reflective events: the height of each point in the OTDR curve represents the back-scattered light intensity at that location. Within a passive optical fiber, the optical signal propagates forward with only ever weaker intensities. But there are places where the reflected signal will appear to bulge out when looking at the OTDR curve as if the optical power at the back is stronger than the front. This is typically the case with the splice, break, and back-scattered peak from fresnel reflection at the end point of the fiber, which is also known as a reflection event. Another situation is fusion splicing, multiple bends, which cause significant losses, where only the rayleigh scattering of the attenuated signal is simple, a position called a non-reflection event.
Optical blind zone of OTDR: the OTDR adopts the scheme of optical time domain signal detection, because the peak power of the signal is limited by the device, the power is limited, and in order to improve the emission energy, the emission pulse width is improved. Fiber outliers in the fiber have a continuous effect on the back-scattered signal during this pulse width time, and optical dead zones are inherent in time-domain detection schemes.
When the OTDR locates the non-reflection event under the condition of a large pulse width (for example, a 0.11dB weak reflection event is tested under the condition of a 2000ns pulse width, and the optical theory dead zone is 200 m), the OTDR is very easily affected by sampling noise due to weak signal starting point characteristics, so that it is very difficult to stably and accurately locate the non-reflection event under the condition of a large pulse width.
The invention provides an OTDR non-reflection event positioning method and device based on template matching, electronic equipment and computer readable storage equipment, and the method and the device are respectively described below.
Referring to fig. 1, in one embodiment of the present invention, an OTDR non-reflection event positioning method based on template matching is disclosed, including:
step S101, acquiring an OTDR sampling signal obtained by returning a preset pulse signal through an optical fiber link;
step S102, determining a detection position of a non-reflection event according to the OTDR sampling signal, and determining a position distribution range of the non-reflection event according to the detection position and a preset pulse signal;
step S103, intercepting the OTDR sampling signal according to the position distribution range to obtain a search signal segment, and determining the attenuation value of the non-reflection event according to the search signal segment;
step S104, scaling a preset attenuation template based on the attenuation value, and performing sliding search in the search signal segment by using the scaled preset attenuation template;
step 105, calculating a correlation coefficient between each sampling point in the search signal segment and a corresponding point in the scaled preset attenuation template, and determining a starting point of the non-reflection event according to the correlation coefficient.
Compared with the prior art, the method of the embodiment comprises the steps of firstly, initially positioning a non-reflection event, determining the position distribution range of the non-reflection event under the condition of large pulse width, intercepting an OTDR sampling signal according to the position distribution range to obtain a search signal segment, and determining the attenuation value of the non-reflection event; secondly, scaling a preset attenuation template based on the attenuation value, and performing sliding search in the search signal segment by utilizing the scaled attenuation template; and finally, calculating the correlation coefficient between each sampling point in the search signal segment and the corresponding point in the scaled preset attenuation template, so as to accurately position the starting point of the non-reflection event. According to the method, the stretching and stretching operation is carried out on the reference attenuation template, the integral matching is carried out on the OTDR signals, the signal characteristics of small attenuation can be identified, and the positioning effect on the non-reflection event is improved. Especially under the condition of large pulse width, the starting point signal of small attenuation is too weak, the position point characteristics are not obvious and are easily influenced by sampling curve jitter.
In a preferred embodiment, in the step S102, determining the location distribution range of the non-reflection event according to the preset pulse signal and the detection location includes:
calculating an optical blind area according to the pulse width of the preset pulse signal and the preset sampling resolution;
and correcting the detection position of the non-reflection event according to the optical blind area to obtain the position distribution range of the non-reflection event.
As a specific embodiment, the OTDR system is subjected to test sampling to obtain an OTDR sampling signal Trace (i), i=1, 2, 3.
The optical dead zone is determined according to the pulse width of a preset pulse signal and the preset sampling resolution, and an algorithm realized by using a python program is as follows:
dead_zone＝int(pluse_width/reso/10)；
where dead zone represents an optical dead zone, plus_width represents pulse width, and resi represents a preset sampling resolution.
The primary position of the detected non-reflection event is represented by x_event, and is often inaccurate due to weak starting point characteristics and noise interference, so that the primary position needs to be corrected to determine the position range of the non-reflection event. The specific program implementation process is as follows:
the event correction range is denoted by [ site_start ], then:
site_start＝x_event-int(1.5*dead_zone)；
site_stop＝x_event+dead_zone；
it should be noted that, the method of this embodiment only corrects the non-reflection event whose position x_event is within the range of [ int (1.5×dead_zone) +2, n-dead_zone-2 ].
In a preferred embodiment, in the step S103, the intercepting the OTDR sampling signal according to the location distribution range to obtain a search signal segment includes:
and intercepting the sampling signals corresponding to the start and stop points of the position distribution range in the OTDR sampling signals to obtain search signal fragments.
Specifically, the segment subtrace=track [ site_start, site_stop ] of the intercepted search signal, and the subscript of the corresponding segment start point in the whole track is start_index=site_start.
In a preferred embodiment, determining the attenuation value of the non-reflective event from the search signal segment comprises:
acquiring a natural attenuation coefficient corresponding to the optical fiber link;
determining an attenuation initial value of the non-reflection event according to the search signal segment, the natural attenuation coefficient and a preset sampling resolution;
and adjusting the attenuation initial value according to a preset correction rule to obtain the attenuation value of the non-reflection event.
In a preferred embodiment, the adjusting the attenuation initial value according to a preset correction rule to obtain the attenuation value of the non-reflection event includes:
and when the attenuation initial value is within a preset minimum attenuation threshold range, taking the preset minimum attenuation threshold as the attenuation value of the non-reflection event.
As a specific embodiment, the above-described process is described below by a specific implementation procedure.
Firstly, selecting corresponding attenuation coefficients att_coeff for different types of optical fibers, wherein the attenuation coefficient of a single-mode optical fiber is approximately 0.192dB/km, namely a natural attenuation coefficient;
second, calculate the decay initial value of the non-reflective event:
event_attenu1＝mean(Trace[site_start-2:site_start+2])-mean(Trace[site_st op-2:site_stop+2])-(site_stop-site_start)*reso*att_coeff；
here, event_attenu1 is an attenuation initial value, mean (Trace [ site_start-2:site_start+2 ]) represents a signal start position, mean (Trace [ site_stop-2:site_stop+2 ]) represents a signal end position, eso represents a preset sampling resolution, att_coeff represents a natural attenuation coefficient, and as shown in fig. 2, the calculation of the attenuation initial value is graphically represented in fig. 2.
When the attenuation initial value is too small (lower than sampling noise jitter and influencing positioning effect), the attenuation initial value is corrected as follows:
if event_attenu1< = 0.1dB, event_attenu = 0.1dB;
if event_attenu1>0.1dB, event_attenu is event_attenu1 unchanged.
In a preferred embodiment, in step S104, scaling the preset attenuation template based on the attenuation value includes:
determining the stretching coefficient of the non-reflection event blind zone according to the signal length of the preset attenuation template and the optical blind zone;
and scaling the preset attenuation template according to the attenuation value, the stretching coefficient, the natural attenuation coefficient and the preset sampling resolution.
The above process is described in detail below by way of a specific example.
As shown in fig. 3, the preset attenuation template is obtained through simulation calculation, fig. 3 is an attenuation event curve of the preset attenuation template, and the attenuation template is expressed as a template (i) by a mathematical formula, i=1, 2. (n_template is the template length, taking n_template as an odd number), the attenuation start point of the template is denoted by offset, offset= (n_template+1)/2.
The tensile coefficient of the signal length of the attenuation template relative to the dead zone of the actual OTDR non-reflection event is expressed by avgs, and then avgs=dead_zone/(N_template-1);
where dead zone represents the optical dead zone and n_template is the signal length of the attenuation template.
For the non-reflection event of the current OTDR sampling signal, the transformation such as stretching and stretching is needed to be carried out on a preset attenuation Template, so that a new Template object template_new [ i ] matched with the current signal after scaling is obtained, and a specific attenuation value scaling formula is as follows:
Template_new[i]＝(template[i]-min(template))/(max(template)-min (template))*event_attenu+(i-1)*avgs*reso*att_coeff,i＝1,2,...N_template；
wherein, template_new [ i ]]Representing the new template that matches, min (template) represents the minimum in the decaying template,max(template)represents the maximum value in the attenuation template, event_attinu represents the attenuation value, avgs represents the stretch factor, eso represents the preset sampling resolution, att_coeff tableShowing the natural attenuation coefficient.
In a preferred embodiment, calculating the correlation coefficient between each sampling point in the search signal segment and the corresponding point in the scaled preset attenuation template includes:
based on the position of the sampling point in the search signal segment, performing sampling value adjustment on the sampling point to obtain an adjusted sampling point;
and calculating the correlation coefficient between the signal value corresponding to the adjusted sampling point in the search signal segment and the signal value corresponding to the scaled preset attenuation template.
In a specific embodiment, the correlation coefficient calculation function is as follows:
Corr(X，Y)＝Cov(X,Y)/sqrt(Cov(X,X)*Cov(Y,Y))；
wherein Cov is a covariance calculation function, and in the scene of the scheme, X is a signal segment with length L, which takes the ith point as the center in a sampling curve; y is the scaled matching template.
In a specific embodiment, using the obtained matching Template template_new, a sliding search is performed in the truncated segment subTrace, and the correlation coefficient Corr is calculated point by point, and the search calculation algorithm is as follows (the used code is python):
because the template is inconsistent with the actual scene pulse width, scaling is needed:
before＝avgs*offset；
the length of the cut search segment is expressed as:
count＝len(sub_trace)；
temp_trace= [0for iin range (len_temp) ], # is pre-opened up in the sub-fragment extraction signal space:
std_corrjdiff_arr= [0for iin range (count) ], # pre-opens up a correlation coefficient space for point-by-point matching of templates,
for iin range (bean+avgs, count-bean-avgs) # searches on sub-segments;
forj in range(len_temp):
ifj＝＝offset:
temp_trace[j]＝sub_trace[i]
in order to improve the jitter of the OTDR sampling curve, # uses sampling points around the sampling points to average as a sampling point value;
elifj<offset:
xi＝i-(offset-j+1)*avgs
xj＝i-(offset-j-1)*avgs
temp_trace[j]＝mean(raw_trace[xi:xj+1])
else:
xi＝i+(j-offset-1)*avgs
xj＝i+(j-offset+1)*avgs
temp_trace[j]＝mean(raw_trace[xi:xj+1])
obtaining matching correlation coefficient arrays std_corr_diff_arr of a matching Template template_new and a matching correlation coefficient array on a subTrace of the decimated signal temp_trace;
std_corr_diff_arr[i]＝Corr(temp_trace,Template_new)
selecting a subscript corresponding to the maximum value in the correlation coefficient number column std_corr_diff_arr [ ]: max_i, the subscript position event_location of the non-reflection event in the whole sampling curve Trace can be obtained, and the point with the highest correlation degree is the starting point of the non-reflection event:
event_location=max_i+start_index, the start_index is the site_start position.
Referring to fig. 4 and fig. 5, fig. 4 is a schematic diagram showing the principle of locating the origin of a non-reflection event by matching a new template, and fig. 5 is a schematic diagram showing the method of the present embodiment in practical application. It should be noted that, in practical application, the method of the present application is mainly aimed at positioning correction of the non-reflection event position in the test scene with the emission pulse width greater than 50 ns.
In summary, according to the method, a theoretical attenuation curve is obtained through simulation calculation; using this theoretical decay curve, template matching can be performed over a substantial range of decay events to stably obtain accurate positioning locations. The method reduces the influence of local sampling noise jitter on event position calculation while improving the positioning accuracy by extracting the whole information, achieves the effect of acquiring the accurate starting point positioning of the non-reflection event through template matching, and solves the problem of accurate positioning of the OTDR system on the non-reflection event especially under the condition of large pulse width.
In order to better implement the template matching-based OTDR non-reflection event positioning method according to the embodiments of the present invention, referring to fig. 6 correspondingly on the basis of the template matching-based OTDR non-reflection event positioning method, fig. 6 is a schematic structural diagram of an embodiment of a template matching-based OTDR non-reflection event positioning system according to the present invention, and an OTDR non-reflection event positioning device 600 according to the embodiment of the present invention includes:
the signal acquisition module 601 is configured to acquire an OTDR sampling signal obtained by returning a preset pulse signal through an optical fiber link;
the position range determining module 602 is configured to determine a detection position of a non-reflection event according to the OTDR sampling signal, and determine a position distribution range of the non-reflection event according to the detection position and a preset pulse signal;
the attenuation value calculation module 603 is configured to intercept the OTDR sampling signal according to the location distribution range, obtain a search signal segment, and determine an attenuation value of the non-reflection event according to the search signal segment;
a sliding search module 604, configured to scale a preset attenuation template based on the attenuation value, and perform sliding search in the search signal segment by using the scaled preset attenuation template;
and the positioning module 605 is configured to calculate a correlation coefficient between each sampling point in the search signal segment and a corresponding point in the scaled preset attenuation template, and determine a starting point of the non-reflection event according to the correlation coefficient.
What needs to be explained here is: the corresponding system 600 provided in the foregoing embodiments may implement the technical solutions described in the foregoing method embodiments, and the specific implementation principles of the foregoing modules or units may be referred to the corresponding content in the foregoing method embodiments, which is not repeated herein.
As shown in fig. 7, the present invention further provides an electronic device 700, which may be a mobile terminal, a desktop computer, a notebook computer, a palm computer, a server, and other computing devices. The electronic device comprises a processor 701, a memory 702 and a display 703.
The memory 702 may in some embodiments be an internal storage unit of a computer device, such as a hard disk or memory of a computer device. The memory 702 may also be an external storage device of the computer device in other embodiments, such as a plug-in hard disk provided on the computer device, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), etc. Further, the memory 702 may also include both internal storage units and external storage devices of the computer device. The memory 702 is used for storing application software installed on the computer device and various types of data, such as program codes for installing the computer device. The memory 702 may also be used to temporarily store data that has been output or is to be output. In an embodiment, the memory 702 stores an OTDR non-reflection event positioning method program 704 based on template matching, where the OTDR non-reflection event positioning method program 704 based on template matching can be executed by the processor 701, so as to implement an OTDR non-reflection event positioning method based on template matching according to embodiments of the present invention.
The processor 701 may in some embodiments be a central processing unit (Central Processing Unit, CPU), microprocessor or other data processing chip for running program code or processing data stored in the memory 702, for example performing a template matching based OTDR non-reflective event localization method procedure or the like.
The display 703 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch, or the like in some embodiments. The display 703 is used for displaying information on the computer device and for displaying a visual user interface. The components 701-703 of the computer device communicate with each other over a system bus.
The present embodiment also provides a computer readable storage medium, on which a positioning program based on the template matching OTDR non-reflection event is stored, which when executed by a processor, can implement the steps in the above embodiments.
The invention provides a template matching-based OTDR non-reflection event positioning method and device. Especially under the condition of large pulse width, the starting point of small attenuation is usually too weak in signal, the position point characteristics are not obvious, and the influence of sampling curve jitter is easy to influence, the method of the application utilizes the reference template to carry out point-by-point matching on the signal near the actually identified OTDR event position, and the positioning accuracy is improved, meanwhile, the influence of local sampling noise jitter on event position calculation is reduced, and the positioning accuracy of a non-reflection event under the condition of large pulse width is effectively improved.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. An OTDR non-reflection event positioning method based on template matching is characterized by comprising the following steps:
acquiring an OTDR sampling signal obtained by returning a preset pulse signal through an optical fiber link;
determining a detection position of a non-reflection event according to the OTDR sampling signal, and determining a position distribution range of the non-reflection event according to the detection position and a preset pulse signal;
intercepting the OTDR sampling signal according to the position distribution range to obtain a search signal segment, and determining the attenuation value of the non-reflection event according to the search signal segment;
scaling a preset attenuation template based on the attenuation value, and performing sliding search in the search signal segment by using the scaled preset attenuation template;
and calculating a correlation coefficient between each sampling point in the search signal segment and a corresponding point in the scaled preset attenuation template, and determining a starting point of the non-reflection event according to the correlation coefficient.
2. The template matching-based OTDR non-reflection event positioning method according to claim 1, wherein determining a position distribution range of the non-reflection event according to the preset pulse signal and a detection position comprises:
calculating an optical blind area according to the pulse width of the preset pulse signal and the preset sampling resolution;
and correcting the detection position of the non-reflection event according to the optical blind area to obtain the position distribution range of the non-reflection event.
3. The template matching-based OTDR non-reflection event positioning method of claim 1, wherein intercepting the OTDR sampling signal according to the location distribution range to obtain a search signal segment comprises:
and intercepting the sampling signals corresponding to the start and stop points of the position distribution range in the OTDR sampling signals to obtain search signal fragments.
4. The template matching based OTDR non-reflective event localization method according to claim 2, wherein determining an attenuation value of the non-reflective event from the search signal segment comprises:
acquiring a natural attenuation coefficient corresponding to the optical fiber link;
determining an attenuation initial value of the non-reflection event according to the search signal segment, the natural attenuation coefficient and a preset sampling resolution;
and adjusting the attenuation initial value according to a preset correction rule to obtain the attenuation value of the non-reflection event.
5. The template matching-based OTDR non-reflection event positioning method according to claim 4, wherein adjusting the attenuation initial value according to a preset correction rule to obtain an attenuation value of the non-reflection event comprises:
and when the attenuation initial value is within a preset minimum attenuation threshold range, taking the preset minimum attenuation threshold as the attenuation value of the non-reflection event.
6. The template matching-based OTDR non-reflection event positioning method of claim 4 wherein scaling a preset attenuation template based on the attenuation value comprises:
determining the stretching coefficient of the non-reflection event blind zone according to the signal length of the preset attenuation template and the optical blind zone;
and scaling the preset attenuation template according to the attenuation value, the stretching coefficient, the natural attenuation coefficient and the preset sampling resolution.
7. The template matching-based OTDR non-reflection event positioning method according to claim 1, wherein calculating a correlation coefficient between each sampling point in the search signal segment and a corresponding point in the scaled preset attenuation template comprises:
based on the position of the sampling point in the search signal segment, performing sampling value adjustment on the sampling point to obtain an adjusted sampling point;
and calculating the correlation coefficient between the signal value corresponding to the adjusted sampling point in the search signal segment and the signal value corresponding to the scaled preset attenuation template.
8. An OTDR non-reflection event positioning device based on template matching, comprising:
the signal acquisition module is used for acquiring an OTDR sampling signal obtained by returning a preset pulse signal through an optical fiber link;
the position range determining module is used for determining the detection position of the non-reflection event according to the OTDR sampling signal and determining the position distribution range of the non-reflection event according to the detection position and a preset pulse signal;
the attenuation value calculation module is used for intercepting the OTDR sampling signal according to the position distribution range to obtain a search signal segment, and determining the attenuation value of the non-reflection event according to the search signal segment;
the sliding search module is used for scaling a preset attenuation template based on the attenuation value, and sliding search is carried out in the search signal segment by utilizing the scaled preset attenuation template;
and the positioning module is used for calculating the correlation coefficient between each sampling point in the search signal segment and the corresponding point in the scaled preset attenuation template, and determining the starting point of the non-reflection event according to the correlation coefficient.
9. An electronic device comprising a processor and a memory, wherein the memory has stored thereon a computer program which, when executed by the processor, implements a method for locating OTDR non-reflection events based on template matching as claimed in any one of claims 1 to 7.
10. A computer readable storage medium storing a computer readable program or instructions which when executed by a processor is capable of carrying out the steps of the template matching based OTDR non-reflection event localization method of any of the preceding claims 1-7.
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