Superior Splicing And Testing Services

By

Pearson Technologies Inc.

(770-490-9991)

Extensive Experience

Pearson Technologies Inc. has been in the fiber optic business for 32 years. Mr. Pearson has 34 years of splicing experience ( http://www.ptnowire.com/ and http://www.ptnowire.com/experience.htm ). In addition, Mr. Pearson has trained more than 7,090 people in both fusion and mechanical splicing.

Well-Equipped Splicing Trailer

Pearson Technologies Inc. has a trailer well equipped for field splicing at client premises, manholes, hand holes, and pedestals. For low loss and high strength splices, the trailer is equipped with temperature control and an electrostatic air cleaner. In addition, this trailer contains the equipment required for testing and troubleshooting. Finally, if indoor splicing is required, the trailer contains the equipment required for such splicing.

Mid-Span And Pigtail Splicing

Pearson Technologies Inc. performs both mid-span and pigtail splicing. While similar, these two types require different knowledge and abilities. During mid-span splicing, routing tends to be straightforward. However, routing in pigtail splicing requires subtle knowledge appropriate to the enclosure and trays to avoid increased loss and reduced reliability.

An important note: pigtail splicing of both singlemode and multimode fibers can be, and usually is, less expensive than field installation of connectors. Prior to contracting for connector installation, clients are well advised to determine the cost advantage of pigtail splicing. See http://www.ptnowire.com/tpp-V3-I2.htm for a detailed analysis. This analysis is for installers, but the conclusion is valid for any client.

Mechanical Splicing

In most situations, mechanical splicing is more expensive than fusion splicing. Under some precisely defined conditions, mechanical splicing can be less expensive or the preferred method. Pearson Technologies Inc. recommends and uses the 3M Fibrlock^® mechanical splice, as it provides consistent low loss for both multimode and singlemode fibers at a competitive cost.

OTDR Testing

Bi-Directional Testing

Pearson Technologies Inc. recommends bi-directional OTDR testing. This recommendation is based on the technical fact that the fibers being spliced can bias the loss high in one direction and low in the opposite direction. Thus, true splice loss is the average of the two directions. Thus, splices that test high loss in one direction may not need re-splicing, as the high loss is intrinsic to the fibers being spliced. Re-splicing such fibers may not result in reduced loss but will result in increased cost.

Our experience is that a splice loss in one direction below 0.35 dB from splices of fibers from different manufacturers frequently averages below 0.15 dB.

Dual Wavelength Testing

Pearson Technologies Inc. recommends testing at two wavelengths. . This recommendation is based on the technical fact that stress on or near the splice can be invisible at one wavelength but visible at the second wavelength. While testing at the second wavelength might be considered sufficient, that wavelength might not be the operational wavelength. Thus, such testing would not simulate operation.

In addition, testing at two wavelengths enables determination of the difference between a high loss splice and incorrect routing of the fiber or buffer tube in the splice enclosure. It is possible, and likely, that incorrect routing can be corrected without re-splicing. Such correction reduces splicing cost and has been our experience.

ORL Testing

ORL testing indicates the total optical power that returns to the transmitter from the link. This power is due to connector reflectance and fiber backscatter. When excessive, such power can result in transmitter misfire and/or failure.

In practice, ORL testing enables determination of excessive connector reflectance. Our experience is that such reflectance occurs from dirty connectors near the end, from which a high ORL value occurs. Cleaning of such connectors results in reduced ORL values and proper operation. Infrequently, such high reflectance connectors need replacement.

Chromatic Dispersion (CD) Testing

CD testing of singlemode fibers determines whether an increase in bit rate is possible. Such testing is performed on ‘old’ fiber that is being upgraded. An example is OC-48 (~2.5 Gbps) to OC-192 (~10 Gbps). If CD is excessive, such fiber cannot be upgraded without replacement of the link, or segments thereof. Pearson Technologies Inc. can perform CD testing quickly and efficiently with CD test equipment.

Polarization Mode Dispersion (PMD) Testing

Similar to CD testing, PMD testing of singlemode fibers determines whether an increase in bit rate is possible. The difference between CD and PMD testing is that PMD testing of ‘old’ fibers may indicate the inability to upgrade the bit rate. ‘Old’ fibers are those installed prior to 1990-1992.

Such inability results from increased dimensional tolerances on core diameter and core circularity. Such dimensions were not considered important for bit rates up to 2.5 Gbps. However, they are critical for transmission at 10 Gbps.

Pearson Technologies Inc. can perform PMD testing quickly and efficiently with PMD test equipment.

BER And Traffic Testing

When PMD or CD testing results are excessive, correction requires replacement of either the entire link or segments thereof. Our experience is that replacement of an entire link is unusual. Rather, replacement of one or more segments is required to achieve low CD and PMD values.

To determine what must be replaced, the tester can test segments. Should this testing reveal the need for link replacement, there is one additional test that can result in elimination of link replacement: BER testing or traffic testing.

The principle for such testing is the fact that all transmission standards are based on worst-case conditions. If such worst case conditions do not exist, it is possible that a high PMD value can be offset by a CD value that is less that the maximum allowed. Thus, traffic or BER testing can eliminate the cost of segment or link replacement.

Dispersion Compensation

In some cases, the total of CD and PMD may be excessive. In these cases, an option to link or segment replacement is: CD compensation. Such compensation can reduce the total dispersion to a level that is acceptable. This solution to excessive dispersion requires BER or traffic testing.

Insertion Loss Testing

The insertion loss test simulates the loss that the transmitter-receiver pair will experience. Thus, this test provides evidence that the pair will function properly. In addition, this test can be used to imply proper, and reliable, installation. However, such installation can be verified only by both insertion loss and OTDR tests.

Singlemode Testing

Singlemode testing simulates operation, as both transmitters and singlemode test sources contain the same type of source. Thus, singlemode testing in compliance with FOTP-7A and TIA/EIA-568-C is straightforward.

Multimode Testing

While singlemode insertion loss testing is straight forward, multimode testing is not. The current multimode testing standard (EIA/TIA-526-14A) requires equipment that is expensive to purchase and maintain (IEC 61280-4-1).

More importantly, such equipment has not proven to provide reproducible results. More than one organization has suggested that this test method is not ready for common use. Thus, Pearson Technologies Inc. recommends use of and tests according to the procedure that preceded the current method.

This procedure is defined in TIA/EIA-568-B and requires a mandrel-wrapped test lead. This procedure provides reproducible results ( http://www.ptnowire.com/eof-V2-I3.htm ).

Link Certification

Link certification is the process of interpreting the insertion loss and OTDR test results. The goal is high reliability. However, the standards do not address reliability except through use of the inadequate maximum loss values. Prior to certifying a link, Pearson Technologies Inc. determines the client’s preferred strategy from among at least three possible strategies. From the strategy, Pearson Technologies Inc. determines acceptance values for each link at both wavelengths.

Test results will indicate compliance with the acceptance values, or lack thereof. If the link cannot be certified, Pearson Technologies Inc. identifies the location at which the lack of compliance occurs. Finally, when possible, Pearson Technologies Inc. identifies the potential cause(s) of such lack. Chapter 19 of Professional Fiber Optic Installation- The Essentials For Success, presents these three strategies ( http://www.ptnowire.com/Sfoi-outline-7.2.htm ).

Date: 1/30/12

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