Patent ID: 12224794

DETAILED DESCRIPTION

For simplicity and illustrative purposes, the present disclosure is described by referring mainly to examples. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures have not been described in detail so as not to unnecessarily obscure the present disclosure.

Throughout the present disclosure, the terms “a” and “an” are intended to denote at least one of a particular element. As used herein, the term “includes” means includes but not limited to, the term “including” means including but not limited to. The term “based on” means based at least in part on.

OTDR event detection and light power level measurement-based fiber optic link certification apparatuses, methods for OTDR event detection and light power level measurement-based fiber optic link certification, and non-transitory computer readable media for OTDR event detection and light power level measurement-based fiber optic link certification are disclosed herein. The apparatuses, methods, and non-transitory computer readable media disclosed herein may utilize, in combination, a light power level measurement by a power meter and an OTDR measurement by an OTDR event detector to identify an event type for a device under test (DUT) of a network, such as a passive optical network (PON) network. For example, the DUT may include a section of the PON network between an optical network terminal (ONT) and a splitter. In this regard, the power meter and the OTDR event detector may be implemented in a device that may be designated as an “Optimeter”.

With respect to the apparatuses, methods, and non-transitory computer readable media disclosed herein, an OTDR may utilize Rayleigh backscattering and Fresnel reflection signals to monitor events with respect to a fiber optic network. One of the unique advantages of OTDR testing is that it utilizes access to one end of a fiber optic cable that may include a plurality of fiber optic links. Since distance and attenuation measurements are based on Rayleigh optical backscattering and the Fresnel reflection principle, returned light may be analyzed directly from the one end of a fiber optic link of the fiber optic cable.

With respect to fiber optic link characterization in a network, such as a passive optical network (PON) network, a DUT that may include a section of the PON network between an ONT and a splitter may need to be certified. In this regard, the PON network may include one or more splitters, and the certification may need to be performed between the ONT and a splitter that is closest to the ONT. The certification may include proper classification of all events associated with the DUT. For example, for a PON network, a DUT may include an event, such as a splitter disposed between an optical line terminal (OLT) and an optical network terminal (ONT). In this regard, it is technically challenging to accurately classify events, such as a splitter, since an OTDR measurement may identify the event as an end of fiber event instead of as a splitter.

In order to address the aforementioned technical challenges, the apparatuses, methods, and non-transitory computer readable media disclosed herein provide for accurate classification of events, such as a splitter, for a DUT for a network, such a PON network, by utilizing light power level measurement in combination with an OTDR measurement. In this regard, based on the utilization of the combined light power level measurement and the OTDR measurement (e.g., OTDR event detection) to classify an event, such as a splitter, an OLT may be disposed after the splitter. The measurement of G-PON wavelength (e.g., 1490 nm) or XGS-PON (or 10G-PON) wavelength (e.g., 1577 nm) light level may be utilized to confirm that an OLT is present beyond an end of the DUT. Yet further, utilization of the light power level measurement may provide for a determination of whether the total loss for the associated fiber optic network is within acceptable bounds.

According to examples disclosed herein, the apparatuses, methods, and non-transitory computer readable media disclosed herein provide for utilization of light power level measurement to enhance OTDR event type detection. In this regard, further analysis may be performed by utilizing multi pulses (e.g., short pulses, and then relatively long pulses as disclosed herein).

According to examples disclosed herein, the apparatuses, methods, and non-transitory computer readable media disclosed herein provide for analysis of combining of an OTDR event detection and light power level measurement to enhance event type, using an optical reflectometer such as an OTDR without disconnecting a fiber optic cable (or a fiber optic link of the fiber optic cable).

For the apparatus, methods, and non-transitory computer readable media disclosed herein, the elements of the apparatus, methods, and non-transitory computer readable media disclosed herein may be any combination of hardware and programming to implement the functionalities of the respective elements. In some examples described herein, the combinations of hardware and programming may be implemented in a number of different ways. For example, the programming for the elements may be processor executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the elements may include a processing resource to execute those instructions. In these examples, a computing device implementing such elements may include the machine-readable storage medium storing the instructions and the processing resource to execute the instructions, or the machine-readable storage medium may be separately stored and accessible by the computing device and the processing resource. In some examples, some elements may be implemented in circuitry.

FIG.1illustrates an architectural layout of a OTDR event detection and light power level measurement-based fiber optic link certification apparatus (hereinafter also referred to as “apparatus100”) in accordance with an example of the present disclosure.

As disclosed herein, the apparatus100may be designated an “Optimeter”, and may include a power meter and an optical reflectometer such as an OTDR.

Referring toFIG.1, the apparatus100may include a power meter102that is executed by at least one hardware processor (e.g., the hardware processor702ofFIG.7, and/or the hardware processor904ofFIG.9), to perform, at one end of a device under test (DUT)104of a network, a light power level measurement106.

An optical time-domain reflectometer (OTDR) event detector108that is executed by at least one hardware processor (e.g., the hardware processor702ofFIG.7, and/or the hardware processor904ofFIG.9) may perform, at the one end of the DUT104, an OTDR measurement110to detect at least one event associated with the DUT104.

An event classifier112that is executed by at least one hardware processor (e.g., the hardware processor702ofFIG.7, and/or the hardware processor904ofFIG.9) may generate, based on analysis of the light power level measurement106and the OTDR measurement110, an event classification114to classify the at least one event associated with the DUT104. In this regard, the at least one event may include events such as optical events, loss incurred, reflectance incurred, a splitter, and other such events, to thus fully certify/qualify the DUT104that includes the fiber network section from an ONT to a splitter as disclosed herein.

According to examples disclosed herein, the event classifier112may generate, based on analysis of the light power level measurement106and the OTDR measurement110, the event classification114to classify, as a splitter116disposed at a second opposite end of the DUT104, the at least one event previously identified by the OTDR measurement110as an end of DUT.

According to examples disclosed herein, the DUT104may include a section of a PON network between an optical network terminal (ONT) and a splitter116.

According to examples disclosed herein, the power meter102may further include a light power level analyzer118that is executed by at least one hardware processor (e.g., the hardware processor702ofFIG.7, and/or the hardware processor904ofFIG.9) to determine, based on an analysis of the light power level measurement106, whether a light power level associated with the DUT104is below a specified light power level (e.g., −35 dBm, or another value that may represent a low power level (LPL) based on sensitivity of associated hardware, photodiodes, acquisition chain instrument sensitivity, etc.). Further, the light power level analyzer118may generate, based on a determination that the light power level associated with the DUT104is below the specified light power level, an indication that there is no light on a passive optical network (PON) wavelength. In this regard, according to examples disclosed herein, the event classifier112may generate, based on analysis of the light power level measurement106and the OTDR measurement110, the event classification114to classify the at least one event associated with the DUT104by generating, based on the light power level measurement106and the OTDR measurement110at a relatively short pulse width (e.g., 10 ns) and at a relatively long pulse width (e.g., 1 microsecond), the event classification114to classify the at least one event associated with the DUT104as an end of DUT. In this regard, according to examples disclosed herein, an actual end of the DUT104may be disposed at a distance from the splitter116, where the distance is less than the relatively short pulse width when testing from the end of the DUT determined by the OTDR measurement110. In other words, the short pulse width may be sufficient to certify from the ONT to the splitter, but is unable to “pass” the splitter loss and hence cannot detect the splitter, while the long pulse width can pass the splitter. Alternatively, the event classifier112may generate, based on analysis of the light power level measurement106and the OTDR measurement110, the event classification114to classify the at least one event associated with the DUT104by generating, based on the light power level measurement106and the OTDR measurement110at a relatively short pulse width (e.g., 10 ns) and at a relatively long pulse width (e.g., 1 microsecond), the event classification114to classify the at least one event associated with the DUT104as an inactive optical line terminal (OLT)122. In this regard, according to examples disclosed herein, an actual end of the DUT104may be disposed at a distance from the splitter116, where the distance is greater than the relatively short pulse width when testing from the end of the DUT determined by the OTDR measurement110.

According to examples disclosed herein, the light power level analyzer118may determine, based on an analysis of the light power level measurement106, whether a light power level associated with the DUT104is below a light power level threshold120(e.g., −27 dBm, or another value based on sensitivity of receptors for a PON network) and above a specified light power level (e.g., −35 dBm). The light power level analyzer118may generate, based on a determination that the light power level associated with the DUT104is below the light power level threshold120and above the specified light power level, an indication of a low passive optical network (PON) signal. In this regard, according to examples disclosed herein, the event classifier112may generate, based on the light power level measurement106and the OTDR measurement110at a relatively short pulse width (e.g., 10 ns), the event classification114to classify the at least one event associated with the DUT104as a splitter.

According to examples disclosed herein, the light power level analyzer118may determine, based on an analysis of the light power level measurement106, whether a light power level associated with the DUT104is above a light power level threshold120(e.g., −27 dBm for a G-PON network). In this regard, the light power level analyzer118may generate, based on a determination that the light power level associated with the DUT104is above the light power level threshold120, an indication of a high passive optical network (PON) signal.

Operation of the apparatus100is described in further detail with reference toFIGS.1-6.

FIG.2illustrates a FTTH PON fiber network between an OLT and an ONT to illustrate operation of the apparatus100, in accordance with an example of the present disclosure.

Referring toFIG.2, the DUT104may include a section of a PON network between an ONT200and a splitter116. In the example ofFIG.2, the splitter is specified as a 1×32 splitter, but may be any other type of splitter, and is disposed 2 km from an OLT122. The apparatus100may include a power meter and an optical reflectometer such as an OTDR, and may be optically connected to the DUT104, instead of the ONT200. The DUT104may include various components, such as a splitter116, connector202, splice204, etc.

When performing a certification on the DUT104for a network, such as a PON network, as disclosed in further detail below with reference toFIGS.2-6, the relatively shorter light pulse width, for example, of 10 ns, may be used to fully characterize the DUT104. However, since the relatively shorter light pulse width may not provide enough dynamic range to measure the splitter116, which may be a last event (e.g., characterized as an end of DUT, or end of fiber optic link) on the DUT104, light power level measurement may be utilized to classify the last event as a splitter. In this regard, the light power level measurement may be performed on a basis that the presence of light indicates that there is fiber optic link beyond what was previously considered an end of the DUT.

As disclosed herein, the apparatuses, methods, and non-transitory computer readable media disclosed herein provide for utilization of light power level measurement to enhance OTDR event type detection. In this regard, further analysis may be performed by utilizing multi-pulses (e.g., short pulse width, and then relatively long pulse width) as disclosed herein.

For example, referring toFIGS.1and2, the power meter102may perform light power level measurement106, for example, at 1490 nm and 1577 nm, for example on a live network utilizing the filtered power meter. The light power level measurement106may be performed directly on a fiber optic cable port124of the apparatus100. The light power level analyzer118may compare the light power level measurement106at each wavelength 1490 nm and 1577 nm to a specified light power level (e.g., −35 dBm, which may represent a low light power level equivalent to “no” light power level) and to a light power level threshold120to classify the light power level measured, for example, into three categories.

A first category may include a no PON signal category for which the light power level measurement106is below, for example, −35 dBm (e.g., the specified light power level, or low light power level equivalent to “no” light power level as disclosed herein). For the first category, there may be no light on the PON wavelength.

A second category may include a low PON signal category for which the light power level measurement may be below the light power level threshold120, for example, of −27 dBm, but above the “no” light power level (or no signal level). For the second category, the PON signal may be too low for adequate characterization.

A third category may include a high PON signal category for which the light power level measurement may be above the light power level threshold120. For the third category, the PON signal may be considered adequate for characterization.

With continued reference toFIGS.1and2, the OTDR event detector108may certify the DUT104(which represents the fiber network from the ONT200to the splitter116), using a short pulse width. For example, the short pulse width may be approximately 10 ns. The OTDR event detector108may perform the OTDR measurement110to generate a result table as described in further detail with reference toFIGS.4and5. The results table may include an indication of optical events along the DUT104.

For example, as shown inFIGS.4and5, the results include distance from the test unit (e.g., the apparatus100) of an optical event at400and500, loss incurred (in dB) at402and502, and reflectance incurred (in dB) at404and504. In addition to these parameters, each optical event may be assigned an event type that describes the physical reality on the fiber optic link. The last event in such a process may be referred to as an end of fiber optic link or end of DUT (e.g., event #4at406and506), whereFIG.4displays an end of a fiber optic link andFIG.5shows an end of DUT.

Referring again toFIGS.1and2, the power meter102may perform light power level measurement106, for example, at 1490 nm and 1577 nm, and further, the OTDR event detector108may certify the DUT104(which represents the fiber network from the ONT200to the splitter116), using a short pulse width. In this regard, the event classifier112may utilize the light power level measurement106to generate the event classification114to further classify the last event detected (e.g., at406ofFIG.4and506ofFIG.5) at the post processing phase of the OTDR event detector108. Thus, the event classifier112may utilize the light power level measurement to generate the event classification114to classify the last event as a splitter, instead of as an end of DUT. For example, with respect to the aforementioned first category that may include a no PON signal category for which the light power level measurement106is below, for example, −35 dBm (e.g., the “no” light power level), the event classifier112may classify an end of DUT event type as an end of DUT (or end of fiber optic link). With respect to the second category that may include a low PON signal category for which the light power level measurement may be below the light power level threshold120, for example, of −27 dBm, but above the no signal level of −35 dBm, the event classifier112may classify an end of DUT event type as a splitter. Further, with respect to the third category that may include a high PON signal category for which the light power level measurement106may be above the light power level threshold120, the event classifier112may classify an end of DUT event type as a splitter.

As disclosed herein, the apparatuses, methods, and non-transitory computer readable media disclosed herein provide for utilization of light power level measurement to enhance OTDR event type detection. In this regard, further analysis may be performed by utilizing multi-pulses (e.g., short pulse width, and then relatively long pulse width). With respect to the further analysis, in order to classify the event type from the OTDR event detector108, the OTDR event detector108may add another OTDR measurement, for example, by adding a long pulse width measurement to increase an accuracy of the event classification.

In order to further enhance the classification of the event type by the OTDR event detector108, after performing power level measurement and then OTDR event detection with a relatively short pulse (e.g., 10 ns) to detect faults on a short link (e.g., <2 km), the event classifier112may determine whether the event type for the end of DUT identified by the OTDR event detector108can be enhanced, or whether another OTDR measurement at a relatively long pulse width (e.g., 1 microsecond) may be needed to properly classify the end of the fiber optic link.

In this regard,FIG.3illustrates a logical flow to illustrate operation of the OTDR event detection and light power level measurement-based fiber optic link certification apparatus ofFIG.1, in accordance with an example of the present disclosure.

Referring toFIGS.1and3, with respect to a determination of whether another OTDR measurement at a relatively long pulse width (e.g., 1 microsecond) may be needed, if the power measured by the power meter102at block300results in a no signal determination (e.g., see first category above), the OTDR event detector108may perform the OTDR measurement110at a relatively short pulse width (e.g., ns) at block302, and may further perform the OTDR measurement110at a relatively long pulse width (e.g., 1 microsecond) at block306for the event classification by the event classifier112at block308. Alternatively, if the power measured by the power meter102at block300results in a PON signal that may be too low for adequate characterization (e.g., see second category above), or a PON signal that may be considered adequate for characterization (e.g., see third category above), the OTDR event detector108may perform the OTDR measurement110at a relatively short pulse width (e.g., 10 ns) at block302for the event classification by the event classifier112at block304.

With respect to the OTDR measurement110at a relatively long pulse width (e.g., 1 microsecond) for block306, the actual end of the DUT104may be determined to be less than the OTDR event dead zone when testing from end of DUT from block302(e.g., case-1), more than the OTDR event dead zone when testing from end of DUT from block302(e.g., case-2), or undetermined.

With continued reference toFIGS.1-3, the aforementioned first, second, and third categories may be specified as follows.

For the actual end of the DUT104that may be determined to be less than the OTDR event dead zone with a short pulse when testing from end of DUT from block302(e.g., case-1), this case-1 may correspond to the aforementioned first category. For example, for the first category that may include a no PON signal category for which the light power level measurement106is below, for example, −35 dBm, the OTDR event detector108may perform the OTDR measurement110at a relatively short pulse width (e.g., 10 ns) at block302, and may further perform the OTDR measurement110at a relatively long pulse width (e.g., 1 microsecond) at block306for the event classification by the event classifier112at block308. In this regard, the event classifier112may utilize both the OTDR measurement110at a relatively short pulse width (e.g., 10 ns) at block302, and the OTDR measurement110at a relatively long pulse width (e.g., 1 microsecond) at block306to confirm the event type at the end of the DUT104.

For the actual end of the DUT104that may be determined to be more than the OTDR event dead zone with a long pulse width when testing from end of DUT from block302(e.g., case-2), this case-2 may also correspond to the aforementioned first category (e.g., where the end of fiber from block306is actually OLT122in the second category). For example, for the first category that may include a no PON signal category for which the light power level measurement106is below, for example, −35 dBm (e.g., the “no” light power level value), the OTDR event detector108may perform the OTDR measurement110at a relatively short pulse width (e.g., ns) at block302, and may further perform the OTDR measurement110at a relatively long pulse width (e.g., 1 microsecond) at block306for the event classification by the event classifier112at block308. However, in this case, the event classifier112may utilize both the OTDR measurement110at a relatively short pulse width (e.g., 10 ns) at block302, and the OTDR measurement110at a relatively long pulse width (e.g., 1 microsecond) at block306to determine that the event type at the end of the DUT104is a splitter, but also indicate that the OLT122is inactive.

With respect to the second category that may include the power measured by the power meter102at block300that results in a PON signal that may be too low for adequate characterization, the OTDR event detector108may perform the OTDR measurement110at a relatively short pulse width (e.g., 10 ns) at block302for the event classification by the event classifier112at block304. In this regard, the event classifier112may generate the event classification114indicating the event as a splitter. In this case, the OTDR measurement110at a relatively long pulse width (e.g., 1 microsecond) at block306may be omitted (e.g., not performed).

With respect to the third category that may include the PON signal that may be considered adequate for characterization, the OTDR event detector108may perform the OTDR measurement110at a relatively short pulse width (e.g., 10 ns) at block302for the event classification by the event classifier112at block304. In this regard, the event classifier112may generate the event classification114indicating the event as a splitter. In this case, the OTDR measurement110at a relatively long pulse width (e.g., 1 microsecond) at block306may be omitted (e.g., not performed).

With respect to block306(e.g., the OTDR measurement110at a relatively long pulse width), the use of a long pulse may be based on the assumption that there is fiber optic link connected after the end of DUT identified at block302, stating that the DUT104is indeed connected to the splitter116, despite the absence of light measured at block300. Alternatively, the use of a long pulse may provide for confirmation that the DUT104ends as determined at block302, the DUT104is not connected to the splitter116, or the splitter116is not connected to a feeder (e.g., fiber network from the OLT122to splitter116).

Referring again toFIG.1, according to examples disclosed herein, the apparatuses, methods, and non-transitory computer readable media disclosed herein provide for analysis of combining of an OTDR fiber link and event detection and light power level measurement to enhance DUT qualification and event type determination, using an optical reflectometer such as an OTDR without disconnecting a fiber optic cable (or a fiber optic link of the fiber optic cable).

With respect to a direction from the splitter to the ONT, in order to certify the DUT104, a direction analyzer126may utilize the light power level measurement106to determine whether the apparatus100is pointed towards the correct equipment (e.g., the ONT, end user of the network and not the OLT, or service provider). In this regard, the light power level measurement106may be performed as disclosed at block300ofFIG.3(e.g., a light power level measurement on specific PON wavelength (e.g., G-PON 1490 nm and XGS-PON 1577 nm)). If the presence of light is detected, the process may end and no other measurement is performed. Alternatively, the certification may be performed by utilizing the OTDR measurement110.

FIG.6illustrates a user interface display to illustrate operation of the apparatus100, in accordance with an example of the present disclosure.

Referring toFIGS.3and6, the user interface display600of the apparatus100may include a display of the event classification114, for example, at the G-PON wavelength (e.g., 1490 nm) or the XGS-PON wavelength (e.g., 1577 nm) light level. The light power level measurement from block300may be utilized to identify the presence of a splitter with either or both wavelengths (e.g., 1490 nm and/or 1577 nm to be above −35 dBm). Yet further, although the examples disclosed herein are described with respect to G-PON wavelength (e.g., 1490 nm) and the XGS-PON wavelength (e.g., 1577 nm), the event identification may also be applied to other types of PON networks and similar technologies.

FIGS.7-9respectively illustrate an example block diagram700, a flowchart of an example method800, and a further example block diagram900for OTDR event detection and light power level measurement-based fiber optic link certification, according to examples. The block diagram700, the method800, and the block diagram900may be implemented on the apparatus100described above with reference toFIG.1by way of example and not of limitation. The block diagram700, the method800, and the block diagram900may be practiced in other apparatuses. In addition to showing the block diagram700,FIG.7shows hardware of the apparatus100that may execute the instructions of the block diagram700. The hardware may include a processor702, and a memory704storing machine readable instructions that when executed by the processor cause the processor to perform the instructions of the block diagram700. The memory704may represent a non-transitory computer readable medium.FIG.8may represent an example method for OTDR event detection and light power level measurement-based fiber optic link certification, and the steps of the method.FIG.9may represent a non-transitory computer readable medium902having stored thereon machine readable instructions to provide OTDR event detection and light power level measurement-based fiber optic link certification according to an example. The machine readable instructions, when executed, cause a processor904to perform the instructions of the block diagram900also shown inFIG.9.

The processor702ofFIG.7and/or the processor904ofFIG.9may include a single or multiple processors or other hardware processing circuit, to execute the methods, functions and other processes described herein. These methods, functions and other processes may be embodied as machine readable instructions stored on a computer readable medium, which may be non-transitory (e.g., the non-transitory computer readable medium902ofFIG.9), such as hardware storage devices (e.g., RAM (random access memory), ROM (read only memory), EPROM (erasable, programmable ROM), EEPROM (electrically erasable, programmable ROM), hard drives, and flash memory). The memory704may include a RAM, where the machine readable instructions and data for a processor may reside during runtime.

Referring toFIGS.1-7, and particularly to the block diagram700shown inFIG.7, the memory704may include instructions706to perform, at one end of a device under test (DUT)104of a network, a light power level measurement106.

The processor702may fetch, decode, and execute the instructions708to perform, at the one end of the DUT104, an OTDR measurement110to detect at least one event associated with the DUT104.

The processor702may fetch, decode, and execute the instructions710to generate, based on analysis of the light power level measurement106and the OTDR measurement110, an event classification114to classify the at least one event associated with the DUT104.

Referring toFIGS.1-6and8, and particularlyFIG.8, for the method800, at block802, the method may include performing, at one end of a device under test (DUT)104of a network, a light power level measurement106by determining, by the at least one hardware processor, based on an analysis of the light power level measurement, whether a light power level associated with the DUT is below a specified light power level, and generating, by the at least one hardware processor, based on a determination that the light power level associated with the DUT is below the specified light power level, an indication that there is no light on a passive optical network (PON) wavelength.

At block804, the method may include performing, at the one end of the DUT104, an OTDR measurement110to detect at least one event associated with the DUT104.

At block806, the method may include generate, based on analysis of the light power level measurement106and the OTDR measurement110, an event classification114to classify the at least one event associated with the DUT104.

Referring toFIGS.1-6and9, and particularlyFIG.9, for the block diagram900, the non-transitory computer readable medium902may include instructions906to perform, at one end of a device under test (DUT)104of a network, a light power level measurement106by determining, based on an analysis of the light power level measurement, whether a light power level associated with the DUT is below a light power level threshold and above a specified light power level, and generating, based on a determination that the light power level associated with the DUT is below the light power level threshold and above the specified light power level, an indication of a low passive optical network (PON) signal.

The processor904may fetch, decode, and execute the instructions908to perform, at the one end of the DUT104, an OTDR measurement110to detect at least one event associated with the DUT104.

The processor904may fetch, decode, and execute the instructions910to generating, based on analysis of the light power level measurement106and the OTDR measurement110, an event classification114to classify the at least one event associated with the DUT104.

What has been described and illustrated herein is an example along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the spirit and scope of the subject matter, which is intended to be defined by the following claims—and their equivalents—in which all terms are meant in their broadest reasonable sense unless otherwise indicated.