Structured Connectivity Solutions Field Testing Guidelines for Fiber ...

SYSTIMAX ® 

Solutions 

Structured Connectivity Solutions 

Field Testing Guidelines for 

Fiber-Optic Cabling Systems 

August 2011 

www.commscope.com

Contents 

Contents 2 

1. Introduction 1 

2. Passive Link Segments 2 

3. General Testing Guidelines 3 

4. Acceptable Attenuation Values 5 

5. Testing Procedure for Single Fiber Connector Solutions 6 

5.1 Test Jumper Performance Verification 7 

5.1.1 Case 1: Matching Connector Types 7 

5.2 Link Segment Testing 9 

5.2.1 Case 1: Matching Connector Types 9 

5.2.2 Case 2: Differing Connector Types. Between Test Equipment and Cabling 10 

5.3 TIA and ISO/IEC Standards 11 

6.1 MPO Case 1: Link with an MPO Trunk Connected to MPO to LC (or SC, ST) 

Modules on Each End 12 

6. Testing Procedure for Solutions Utilizing MPO Connectivity 12 

6.2 MPO Case 2: MPO Trunk Cable Testing Only For 40/100G Applications 

or When MPO-LC Harnesses Will be Connected at a Later Date 14 

7. Testing Procedure - MPO Solutions 15 

7.1 Cable Plant Defect Detection and Resolution 15 

7.2 Test Equipment Checklist 16 

Appendix A 17 

Appendix B 19 

Mandrel Wrap Prescriptions 19 

Appendix C: Encircled Flux Control (Optional for Field Testing) 20 

Test Instrument Data Sheet 21 

Link Attenuation Measurement Record for Power Meters Displaying 

Absolute Power Levels 22 

Link Attenuation Measurement Record for Power Meters Displaying 

Absolute Power Levels 23 

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1. Introduction 

The following guidelines describe SYSTIMAX ® 

Solutions’ recommended procedure for field 

testing multimode and singlemode cabling systems. SYSTIMAX Solutions TM 

only requires testing 

of link attenuation for Enterprise networks. While other fiber-optic cabling system parameters 

such as bandwidth are equally important, they are not normally affected by the quality of 

the installation and therefore, do not require field testing. This document describes how and 

where attenuation testing should be performed For enterpise systems. TIA-568C.0 ANNEX E 

(Informative) Guidelines For Field-Testing Length, Loss And Polarity Of Optical Fiber Cabling 

provides guidelines for testing optical fiber systems. Optical loss (link attenuation), length 

verification, and polarity testing are defined here as Tier 1 testing, while OTDR testing is a Tier 

2 and optional test. This document replaces the previous revision dated March 2005. 

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2. Passive Link Segments 

Attenuation testing should be performed on each passive link segment of the cabling system. 

A link segment consists of the cable, connectors, couplings, and splices between two fiberoptic 

termination units (patch panels, information outlets, etc.). Each terminated fiber within 

a link segment should be tested. The link segment attenuation measurement includes the 

representative attenuation of connectors at the termination unit interface on both ends of the 

link, but does not include the attenuation associated with the active equipment interface. 

This is illustrated in Figure 1. 

Figure 1. Tested Link Segment 

There are three basic types of link segments described in this document: horizontal, backbone, 

and composite. A horizontal link segment normally begins at the telecommunications outlet and 

ends at the horizontal cross-connect. The telecommunications outlet may be a multi-user outlet 

placed in an open office area. The horizontal link segment may also include a consolidation 

point interconnection or a transition point splice. A riser backbone link segment usually begins 

at the main cross-connect and ends at the horizontal cross-connect. For the purposes of this 

document, a tie cable (placed between two horizontal cross-connects) and a campus cable 

(typically placed between two main cross-connects) are both considered backbone link 

segments. Single Point Administration architecture (i.e. Centralized Cabling) eliminates the 

horizontal cross-connect, and therefore horizontal and backbone cabling are combined into a 

composite link segment. In this case, the horizontal closet may contain a splice, interconnect, 

or pulled-through cable. 

Note: Spliced pigtail terminations at one or both ends of a horizontal, backbone, or composite link are permitted. 

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3. General Testing Guidelines 

SAFETY NOTE: Unterminated connectors may emit radiation if the far end is connected to a laser 

or LED. Do not view the end of a cable until absolutely sure that the fiber is disconnected from 

any laser or LED source. The best practice would be to only view the end face of a connector 

through a scope and view, so that no direct eye contact is possible the laser light. Today’s 

inspection kits are available to view multifiber MPO connectors as well as single-fiber types. 

• Multimode horizontal link segments should be tested in one direction at EITHER 850 nm 

or 1300 nm wavelength. 

• Multimode backbone and composite link segments should be tested in one direction at 

850 nm and 1300 nm wavelengths. 

• Singlemode horizontal link segments should be tested in one direction at EITHER 1310 nm 

or 1550 nm wavelength. 

• Singlemode backbone and composite link segments should be tested in one direction at 

BOTH 1310 nm and 1550 nm wavelengths. 

Note 1: Horizontal link segments are short enough that attenuation differences caused by 

wavelength are insignificant. As a result, single wavelength testing is sufficient. Backbone and 

composite links may be longer, and attenuation may strongly depend on wavelength in such 

links. Therefore, it is necessary to test at both wavelengths. 

Note 2: The minor attenuation differences due to test direction are on par with the accuracy 

and repeatability of the test method. Therefore, testing in only one direction normally suffices. 

However, test in both directions if the installation contains fibers of different core sizes. This is 

to detect inadvertent mixing of fibers with different core sizes, as the loss in one direction will 

differ from the loss in the other direction by at least 2 dB if different core sizes are connected 

together (e.g. 50 µm connected to 62.5 µm) when measured using 62.5 µm test jumpers. 

Note 3: Today’s standards only ask for uni-directional OLTS testing, however many customers 

are requesting bi-directional results. While bi-directional OLTS testing may provide more data, 

there is a trade-off with the extra time required and the additional opportunity for dirt and dust 

to be introduced during the testing process. Bi-directional test results are optional; if used, the 

direction with the higher loss measurement would be used to determine pass/fail for the link. 

SYSTIMAX Solutions requires multimode field tests to be performed with a launch condition as 

defined in TIA-526-14B. Defining a particular launch condition reduces measurement error 

and variability. This particular launch will produce field measurements that correlate well with 

component specifications. This launch condition can be closely and easily approximated in the 

field by using a Category 1 Coupled Power Ratio (CPR) source with a specific mandrel wrap 

on the launch test jumper. TIA-526-14B describes the test procedure to categorize the CPR of 

a multimode light source, with instructions on creating the proper mandrel wrap. 

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In compliance with TIA/EIA-526-14B “Optical Power Loss Measurements of Installed 

Multimode Fiber Cable Plant”, IEC 61280-4-1 edition 2, Fibre-Optic Communications 

Subsystem Test Procedure – 49 Part 4-1: Installed cable plant – Multimode attenuation 

measurement – OFSTP-14, TIA/EIA-526-7 “Measurement of Optical Power Loss of Installed 

Singlemode Fiber Cable Plant”, and IEC 61280-4-2 ed 1 Fibre optic cable plant - Singlemode 

fibre optic cable plant attenuation the following information should be recorded during 

the test procedure: 

1. Names of personnel conducting the test. 

2. Type of test equipment used (manufacturer, model, and serial number). 

3. Date test is being performed. 

4. Optical source wavelength, spectral width, and CPR (for multimode tests only). 

5. Fiber identification. 

6. End point locations. 

7. Test direction. 

8. Reference power measurement (when not using a power meter with a Relative Power 

Measurement Mode). 

9. Measured attenuation of the link segment. 

10. Acceptable link attenuation. 

Note: Horizontal link segments are often all within 90 meters; therefore, the acceptable link attenuation can be 

based on the longest installed link without introducing a significant error in cases where this shorter distance is 

maintained 100%. However, if the design calls for horizontal runs of longer than 90 meters, than there would likely 

be more variation and it would not be as accurate to use only the longest run to estimate loss. 

See the end of this document for sample measurement recording forms. 

IMPORTANT NOTE: Ensure that all connectors/modules are cleaned prior to mating trunk 

cables or patch cords. 

Contamination as small as 0.001 mm can block the fiber core generating strong back 

reflections (Return Loss) and may effect attenuation (Insertion Loss). Mating a contaminated 

connector to a clean connector will result in poor performance and can permanently damage 

the connection. CommScope recommends that fiber optic connectors are inspected with a 

microscope prior to mating. 

Please refer to the CommScope Fiber Optic Connector and Adapter Cleaning Procedures 

and the CommScope Fiber Optic Connector Cleaning and Inspection kit for more detailed 

information. Also refer to Section 7. 

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4. Acceptable Attenuation Values 

OLTS testing is used to evaluate the overall loss of an entire optical link. Although individual 

component specifications can be reviewed on each component’s specification sheet, simply 

adding these values together would likely overestimate the loss of that link. CommScope 

provides a link loss calculator that can be used to determine the maximum acceptable loss 

for each link evaluated. 

Information to be entered into the link loss calculator: 

1. Fiber type 

2. Fiber length in feet or meters 

3. Wavelength tested 

4. Connector types 

5. Number of connections 

The attenuation for any link segment can be calculated using the latest version of 

the CommScope Fiber LinkLoss Calculator. This calculator can be downloaded from 

mycommscope.com website or please consult your local CommScope representative. 

An example of the format for the Fiber LinkLoss Calculator, available at www.mycommscope.com, 

is given in Figure 2. 

Figure 2 

A connection is defined by the joint made by mating 2 fibers terminated with rematable 

connectors (LC, SC, MPO, etc). For example, an LC connector pair made up of 2 connectors, 

would count as only 1 connection within the link loss calculator. 

When using the InstaPATCH 360 module, each module actually contains two (2) connection 

points. This equates to 1 x LC/SC/ST and 1 x MPO per module for the Fiber LinkLoss 

Calculator. 

The value provided is the maximum acceptable loss that is allowable to ensure that the solution 

will meet the performance as described in the CommScope Performance Specifications guides. 

Note that this loss will likely be LESS than would be defined by TIA and I EC standards. 

Additionally, this value will also likely be LESS than would be calculated by adding the 

potential loss of all individual components together. 

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5. Testing Procedure for Single 

Fiber Connector Solutions 

The basic steps for performing field attenuation measurements are: 

1. verify test jumper performance (see section 5.1), 

2. obtain a reference power level (see section 5.2), 

3. measure link power throughput (see section 5.2), 

4. calculate and record link attenuation (see section 5.2). 

Two worksheets in the back of these guidelines may be used for recording measurement 

information. The first is for use with power meters that display absolute power levels without 

a selectable reference. The second is for power meters that display power levels relative to a 

measured reference level. Of course today most test sets will allow the user to record the data 

within the test units to later access electronically. This is the preferred method of record keeping. 

If the power meter supports measurements relative to a previously made reference measurement 

(in units of dB), select this mode, as such readings do not necessitate manual calculation. If the 

meter does not have a Relative Power Measurement mode, perform the following calculation to 

determine attenuation: 

• If P sum and P ref are in the same logarithmic units (dBm, dBu, etc.): 

Attenuation (dB) = | P sum /P ref | 

• If P sum and P ref are in the same linear units (watts, milliwatts (mw), mircowatts (µw)): 

Attenuation (dB) = | 10 x LOG10 [P sum /P ref ]| 

Where: P sum is the power reading of the item under test, 

P ref is the power level of the reference measurement. 

Caution: Stable reference power levels are critical to the accuracy of subsequent attenuation 

measurements. Instability may arise from at least two common causes: battery health and 

mechanical changes at the connection to the source. Ensure the battery is in good operating 

condition and fully charged in both the source and power meter. Avoid disturbing in any way 

the connection from the source to the test jumper after the reference measurement. Disturbances 

include disconnection, lateral side-loading, and axial tension. Any of these disturbances 

is cause for making a new reference measurement. The chances for encountering these 

disturbances may be minimized by securing the launch test jumper to the source test set by 

means of tape or cable tie applied at the mandrel or mode suppression loop (described later). 

SYSTIMAX Solutions requires all multimode jumper performance verifications and link attenuation 

measurements to be performed with a launch condition as defined in TIA-526-14B. This launch 

condition can be approximated in the field by using a Category 1 CPR source with a specific 

mandrel wrap on the launch test jumper. Refer to Appendix A for instructions on measuring the 

CPR of the light source. Refer to Appendix B for instructions on creating the proper mandrel wrap. 

Category 1 CPR sources are generally LEDs (Light Emitting Diodes). 

Caution: CommScope does not recommend the use of Vertical Cavity Surface Emitting Laser 

(VCSEL)-based light sources as the primary light source for testing multimode fiber links. This is due 

to the fact that there is a large variability in VCSEL launch conditions that may lead to significant 

measurement variability. This variability also diminishes any correlation to the attenuation seen by 

VCSEL-based applications. In addition VCSEL-based sources do not normally produce Category 1 

CPR. Use of a Category 1 CPR source with a mandrel wrapped test jumper provides a standard 

launch condition that strikes a good balance between LED and VCSEL-based application needs 

while reducing measurement variability, increasing measurement repeatability and improving 

agreement between different test sets. Therefore the mandrel-wrapped Category-1 CPR launch 

condition is required for baseline attenuation measurements. VCSEL-based launch conditions may 

be added as supplemental information, but the results may be over-optimistic, even if the cable 

plant is intended to support VCSEL-based applications. 

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SYSTIMAX Solutions requires all singlemode jumper performance verifications and link 

attenuation measurements to be performed with a launch test jumper containing a single loop 

< 30 mm (1.2 inches) in diameter to suppress multimode propagation. This loop may be 

created by either wrapping the jumper around a mandrel or in free space by securing the 

jumper to itself. 

5.1 Test Jumper Performance Verification 

In compliance with TIA/EIA-526-14B and TIA/EIA-526-7 (and IEC equivalents), test jumpers 

shall be 1 - 5 meters long, and have the same fiber construction (i.e. core diameter and 

numerical aperture) as the link segment being tested. Before carrying out any test, clean the 

test jumper connectors and test coupling. 

Follow the procedure for one of the following two cases that corresponds to the particular 

cable plant and test set connector types. Follow section 5.1.1 in cases where the connector 

type on the cable plant matches that of the test set. 

5.1.1 Case 1: Matching Connector Types 

Procedure: 

1. Prepare the required launch test jumper (test jumper-1) with the necessary mandrel wrap 

for multimode measurements or mode suppression loop for singlemode measurements. 

2. Clean all test jumper connectors and the test coupling per the manufacturer’s instructions. 

3. Follow the test equipment manufacturer’s initial adjustment instructions. 

4. Connect test jumper-1 between the light source and the power meter. See Figure 4. 

Figure 3 

Light 

Source 

Test Jumper-1 

TX RX 

Mandrel Wrap 

Power 

Meter 

5. Record the Reference Power Measurement (Pref) or, preferably, select the power meter’s 

Relative Power Measurement Mode. 

6. Disconnect test jumper-1 from the power meter. 

7. Connect test jumper-2 between the power meter and test jumper-1 using the test coupling. 

See Figure 5. 

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Figure 4 

Light 

Source 

TX 

Test Jumper-1 Test Jumper-2 

Mandrel Wrap 

Coupling 

(Adapter) 

8. Record the Power Measurement (Psum). Perform the calculations given in section 5 if not 

using Relative Power Measurement mode. This measurement provides the attenuation of the 

cable of test jumper-2 plus the connection between test jumper-1 and test jumper-2. The 

measured attenuation must be less than or equal to the corresponding value given in Table 

4. Unacceptable attenuation measurements may be attributable to either of the test jumpers. 

Examine each jumper with a portable microscope and clean, polish, or replace if necessary. 

9. Flip the ends of test jumper-2 so that the end connected to the power meter is now connected 

to the coupling, and the end connected to the coupling is now connected to the power meter. 

10. Record the new Power Measurement (Psum). Perform the calculations given in section 5 if 

not using Relative Power Measurement Mode. The attenuation must be less than or equal 

to the corresponding value found in Table 4. 

TABLE 4 ACCEPTABLE TEST JUMPER ATTENUATION 

Fiber Type Connection Type Between Test Jumpers 

ST or SC LC 

Power 

Meter 

62.5 µm Multimode 0.50 dB Max 0.20 dB Max 

LazrSPEED 50 µm 0.50 dB Max 0.28 dB Max 

Singlemode 0.55 dB Max 0.30 dB Max 

If both measurements are found to be less than or equal to the values found in Table 4, test 

jumper-2 is acceptable for testing purposes. 

11. Repeat this test procedure from the beginning reversing jumper-1 and jumper-2 in order to 

verify the performance of test jumper-1. Remember to remove the existing mandrel or loop 

from former test jumper-1 and apply the same to new test jumper-1 (former test jumper-2). 

RX 

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5.2 Link Segment Testing 

In order to include all connections in the measurement, the One Reference Jumper Method 

specified in TIA/EIA-526-14B (for multimode fibers) and TIA/EIA-526-7 (for singlemode 

fibers) shall be used to test each link segment. This procedure, adapted to address two cases, 

is summarized in the next two sections. Follow section 5.2.1 in cases where the connector 

type on the cable plant matches that of the test set. Follow section 5.2.2 for cases where the 

connector type on the cable plant differs from that on the test set. 

5.2.1 Case 1: Matching Connector Types 

Procedure: 

1. Use known-good test jumpers, each verified by following the procedure in section 5.1.1. 

2. Prepare the required launch test jumper (test jumper-1) with the necessary mandrel wrap 

for multimode measurements or mode suppression loop for singlemode measurements 

(Test Jumper-1 in Figure 8). 

3. Clean the test jumper connectors per the manufacturer’s instructions. 


5. Connect test jumper-1 between the light source and the power meter. See Figure 8. 

Figure 5 

Light 

Source 

Test Jumper-1 

TX RX 

Mandrel Wrap 

Power 

Meter 

6. Record the Reference Power Measurement (Pref) or, preferably, select the power meter’s 

Relative Power Measurement Mode. 

7. Disconnect jumper-1 from the power meter and connect it to test jumper-2. Do NOT 

disconnect the test jumper from the light source. Connect the other side of jumper-2 to 

the meter port. Verify that the connector loss is at or below the value shown in Table 4 

above. 

8. Separate jumper-1 from jumper 2 and connect to the ends of the system under test. 

DO NOT make any disconnections at the source or meter ports. Connect test jumper-2 

between the other end of the link segment and the power meter. Verify the loss is equal to 

or less than the value shown in the link loss calculator. 

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Figure 8 

Test Jumper-1 LINK SEGMENT 

Test Jumper-2 

Light 

Power 

TX RX 

Source 

Meter 

Mandrel 

Wrap 

Splice 

Interconnection 

Termination Unit: 

Patch Panel, Faceplate, etc. 

w/Coupling 

9. Record the Power Measurement (P sum ). Perform the calculations given in section 5 if not 

using Relative Power Measurement mode. This measurement provides the attenuation of 

the link segment cable(s), splice(s) and connections, including the connections on its ends. 

If the measurement value is less than or equal to the value calculated using the attenuation 

equation (see section 4), the link segment attenuation is acceptable. If not acceptable see 

section 6 for troubleshooting guidance. 

5.2.2 Case 2: Differing Connector Types. Between Test Equipment and Cabling 

The One Jumper Reference Method in TIA/EIA-526-14B (for multimode fibers) and TIA/EIA- 

526-7 (for singlemode fibers) assumes the test equipment to have the same connector type as in 

the link under test. The three reference jumper test method outlined in the previous CommScope 

Fiber Testing Guidelines (dated March 2005, section 5.2.2) is no longer needed, except 

when testing InstaPATCH trunk cables only (see section 6). This modified adaptation method is 

necessary when the optical power loss meter receptacle did not mate with the connector of the 

installed cabling. 

Today’s equipment should have a meter port that can be replaced to match the field connector. 

This will allow the technician to adjust the connector types as needed to provide a true 

1-jumper reference. Follow the procedures outlines in 5.2.1, changing out the meter port as 

required to have the appropriate connector type. 

Hence, starting 15th October 2004, CommScope requires the use of optical power loss 

meters directly compatible with the cabling plant. Some manufacturers and their products that 

offer this feature are: 

• AFL (alcoa.com/afl_tele): MLP, SLP series 

• Exfo (exfo.com): FOT-920 

• Fluke (flukenetworks.com): Certifiber, Simplefiber, DTX-1800 CableAnalyser (with DTX-MFM2 

fiber modules and NFA-LC adapters) 

Note that the cord on the source side is not removed and therefore the source port does not 

need to be adjustable. A cord with different connector types on each end may be needed here 

to connect to the source port and the field connector. 

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Figures 7 and 8 show the test set-up to evaluate an optical link with LC connections and 

LC-SC patch cords when the test equipment provided has an SC optical source port and an 

adjustable meter port. 

Figure 7 - Reference set-up 

5.3 TIA and ISO/IEC Standards 

ISO/IEC 14763-3 covers ‘Implementation and Operation of Customer Premises Cabling: 

Testing of Optical Fiber Cabling’ and references 

• IEC 61280-4-1 for installed multimode fiber optic cable plant attenuation measurement 

• IEC 61280-4-2 for installed singlemode fiber optic cable plant attenuation measurement 

Besides the TIA/EIA-526-14B and TIA/EIA-526-7 standards already discussed, TIA568C.0 

and C.1 covers ‘additional guidelines for field testing length, loss and polarity of optical fiber 

cabling systems’. 

Table 2 provides the link configurations and the associated reference test methods required by 

the different standards. 

TABLE 2 - LINk CONFIGURATIONS AND THE ASSOCIATED REFERENCE TEST METHODS 

Link Configurations 

(Numberof connections 

included inloss measurement) 

Common 

Terminology 

1-Jumper Reference 

Photos courtesy of Fluke ® 

Network 

1. Disconnect from Meter Port 

2. Add Test Jumpers at the 

Meter and validate mating 

3. Test the system 

TIA/EIA-526-14B 

(Multimode) 

TIA/EIA-526-7 

(Singlemode) 

Meter port adapters should be 

interchangeable for ease of 

referencing and testing 

Testing an LC system with LC-SC 

duplex Jumpers: 

•LC port needed for referencing 

•SC port needed for testing 

Figure 8 - System Test 


Network 

IEC 61280-4-1 

(Multimode) 

IEC 61280-4-2 

(Singlemode) 

1 2-jumper method Method A Method A.2 Annex C Method A.2 

2 (i.e. panel-to-panel links) 1-jumper method Method B Method A.1 Annex A Method A.1 

2 (Adaptation) 3-jumper method Method C Method A.3 Annex B Method A.3 

The CommScope testing guidelines are in accordance with TIA and IEC 61280-4 series of 

standards. The 1-jumper method is the most conservative and commonly used. Technicians 

should default to using the 1-jumper reference method in almost all cases. 

Note that Optical Time Domain Reflectometer (OTDR) test is optional for CommScope. 


6. Testing Procedure for Solutions 

Utilizing MPO Connectivity 

With the inevitable migration to applications using parallel optics technologies such as 

40G/100G Ethernet, there is a need to test link segments consisting of MPO array cabling, 

as seen within the CommScope InstaPATCH 360 solution. The MPO connector allows for 

the consolidation of many fibers within one array. Although typically provided with 12 fibers, 

an MPO may house 8 or 24 fibers less commonly, with other values of fibers possible. The 

discussion and figures will focus on 12-F MPO solutions, but the process is relevant to the others. 

6.1 MPO Case 1: Link with an MPO Trunk Connected 

to MPO to LC (or SC, ST) Modules on Each End 

In this case, the link can be tested through the single-fiber connections and the testing process 

will not significantly change. The technician can follow the procedures outlined in section 5. 

As you can see in figure 9, the MPOs are behind the wall and not connected directly to the 

test cords. If testing 2 fibers at a time, the technician could test all 12 fibers of the MPO link 

with 6 individual tests. 

Figure 9 

400 m (1312 ft) 

Courtesy of Fluke ® 

Network 


Figure 10 MPO-LC harnesses may take the place of MPO-LC modules and LC 

duplex patch cords 

The extra connector pairs do need to be accounted for within the link loss calculator however. 

An MPO to LC (or SC, ST) module will count as 2 connections on each side. The MPO and 

single-fiber connections make separate connections. The user should add 1 connection for both 

the single-fiber and MPO connector within the link loss calculator. In contrast, use of an MPO to 

single-fiber array cord (figure 10) will likely only count as 1 MPO connection, as the single-fiber 

connector will likely be plugged directly into the electronics. 

In the test shown in figure 9 above, there are 2 MPO connections and 2 LC connections. An 

example of how the link loss calculator can be used to determine the maximum loss for this link 

is show in figure 11. 

Figure 11 



Network 

6.2 MPO Case 2: MPO Trunk Cable Testing – For 

40/100G Applications or When MPO-LC Harnesses 

Will be Connected at a Later Date 

In this case, there are no single-fiber connectors to attach traditional single-fiber test cords to. 

In a laboratory setting, there would be test equipment available that could directly to MPO 

connectors. This would require a mix of 12 output sources and either 12 input ports or an 

MPO port with a very wide area adapter to accept the light from all 12 (or 24 fibers). This 

set-up is fairly impractical for field-testing today. 

Instead, the technician should use an MPO to LC break-out patch cord to separate the trunk 

into single-fiber channels for testing. Because of the additional cords, a 3-jumper reference is 

required to account for the additional loss of test connections. 

The basic steps for performing field attenuation measurements of an MPO trunk are: 

1. Verify test jumper performance (see section 5.1), 

2. Obtain a reference power level (Fig X1, X2, X3). There should >= 0.1 dB of power 

difference between X1 and X2, X2 and 

3. Reference the unit to 0.0 dBr with the 3 LC patch cords in place 

4. Remove the middle patch cord and add an LC to MPO array cord on each side (FigX4) 

5. Attach the MPO-LC cords to the MPO trunk and measure the loss at the first LC duplex 

6. Record and measure the loss at the 2nd LC duplex and continue to the last connection 

Figure 12 

Note: EVERY test must measure at or below the maximum value obtained in the link loss calculator in order for the 

entire MPO link to be acceptable. Even one value above the maximum allowable loss would cause the entire link to 

be considered a failure. 

Section 7 refers to contamination and cleaning procedures. MPO solutions are particularly 

susceptible to contamination because of the number of fibers, number of connections, and tight 

loss budgets. Frequent cleaning may be required. 


Figure 13 

7. Testing Procedure - MPO 

Solutions 

Link attenuation exceeding expectations may arise from several reasons. These include defects 

in the cable plant or improper test equipment. 

7.1 Cable Plant Defect Detection and Resolution 

Contamination is the most common cause of optical loss within connections. For multimode and 

single-mode cabling the test jumpers and the ports under test should be clean and – free of 

damage in accordance with IEC-61300-3-35. Check connector end-faces for dirt and defects 

(see Table 5 and Figures 13 and 14), and check link segment for broken fiber, poor splices 

and tight bends. 

TABLE 5 

Possible Cause Resolution 

Adhesive bead left on the tip of a connector Examine connectors with a portable microscope and 

re-polish if necessary 

Poorly polished connectors (see Figure 13) Examine connectors with a portable microscope and 

re-polish if necessary 

Dirty connectors and/or couplings (see Figure 13) Examine connections and clean per manufacturer’s 

instructions 

Broken fiber Identify break with a Visible Fault Locator or OTDR 

and splice fiber or replace cable 

Poor mechanical or fusion splices Identify poor splices with a Visible Fault Locator or 

OTDR and re-splice if necessary 

Patch cord does not match the fiber type 

(compare jacket color and print statement) 

of the behind-the-wall cabling 

Patch cord does not match the fiber type 

(compare jacket color and print statement) 

of the behind-the-wall cabling 

Figure 14 

Identify tight bends by inspection or with a 

Visible Fault Locator or OTDR and increase 

the bend radius above minimum specifications 

Replace test leads to match BTW cabling. 

Reset the reference and retest. 

Good and Clean Connector Fingerprint on Connector 

Dirty Connector One dirty fiber of an MPO Clean MPO fibers 

Pictures courtesy of Fluke Networks 


7.2 Test Equipment Checklist 

q Check Test Jumper Conformance 

Follow Section 5.1 to verify that the performance of test jumpers used conform to values given 

in Table 4. 

q Check Light Source Conformance 

Follow Appendix A to verify that the CPR value for the light source used conforms to values 

given in Table A1. 

q Check Mandrel Wrap Dimension Conformance 

Follow Appendix B to verify proper usage of mandrel wraps during testing. Verify that the 

mandrel wrap dimension conforms to values given in Table B1. 

q Check Reference Level Stability 

Ensure battery operated equipment have batteries in good condition with sufficient charge. 

Ensure that the connection of test jumper-1 to the light source is not disturbed after the reference 

level measurement. Disturbances include disconnection and reconnection, lateral or axial 

stresses such as tugging, bumping the connector, or bending the cordage. Any of these may 

be sufficient cause for re-measurement of the reference level and any cable plant attenuation 

values taken after the disturbance. Stability of the references may be improved by securing test 

jumper-1 (the launch jumper) to the source test set by means of tape or cable tie, usually at the 

mandrel or mode suppression loop. 


Appendix A 

Coupled Power Ratio (CPR) Measurement 

SYSTIMAX Solutions requires field tests to be performed with a launch condition as defined in 

526-14B. This launch condition can be closely and easily approximated in the field by using 

a Category 1 CPR light source with a mandrel wrap on the launch test jumper (mandrel wraps 

are described in Appendix B). Generally, LED-based light sources produce a Category 1 CPR 

launch. 

Note: The Coupled Power Ratio of a light source is a measure of the modal power distribution launched into 

a multimode fiber. A light source that launches most of its power into just the lower order modes produces an 

underfilled condition, which can result in optimistically low link attenuation measurements. A light source that 

launches a high percentage of its power into higher order modes produces a more over-filled condition, which 

can create higher link attenuation measurements. A Category-1 source typically produces a near over-filled launch 

condition, and can produce overly pessimistic attenuation values for the link due to excitation of high-order transient 

modes that attenuate rapidly. The addition of a mandrel wrap filters out these high-order transient modes from the 

launch condition. By consistently using Category-1 sources with a mandrel wrap, the variability due to the test set is 

reduced and the error in the measurements diminishes. 

CPR Test Jumper Requirements: 

CPR Test Jumper-1 shall be multimode, 1 - 5 meters long with connectors compatible with the 

light source and power meter, and have the same core size and numerical aperture as the link 

segment being tested. 

CPR Test Jumper-2 shall be singlemode at the wavelength used for testing, 1 - 5 meters 

long with connectors compatible with the light source and power meter. Caution: Standard 

singlemode fiber is not singlemode for 850 nm tests. Special singlemode fiber must be used for 

CPR measurements at 850 nm. 

Procedure: 

1. Clean the test jumper connectors and the test coupling per manufacturer’s instructions. 


3. Connect multimode test jumper-1 between the light source and the power meter. Avoid placing 

bends in the jumper that are less than 100 mm (4 inches) in diameter. See Figure 15. 

Figure 15 

Light 

Source 

CPR Test Jumper-1 

(multimode) 

TX RX 

Power 

Meter 

4. If the power meter has a Relative Power Measurement Mode, select it. If it does not, 

record the Reference Power Measurement (P ). Note: If the meter can display power levels 

ref 

in dBm, select this unit of measurement to simplify subsequent calculations. 

5. Disconnect test jumper-1 from the power meter. Do NOT disconnect the test jumper from 

the light source. 

6. Connect singlemode jumper-2 between the power meter and test jumper-1 using the test 

coupling. The singlemode jumper should include a high order mode filter. This can be 

accomplished by wrapping the jumper around a 30-mm (1.2-inch) diameter mandrel. See 

Figure 16. 


Figure 15 

7. Record the Power Measurement (P ). If the power meter is in Relative Power Measurement 

sum 

Mode, the meter reading represents the CPR value. If the meter does not have a Relative 

Power Measurement Mode, perform the following calculation: 

• If P and P are in the same logarithmic units (dBm, dBu, etc.): 

sum ref 

CPR (dB) = | P sum - P ref | 

• If P sum and P ref are in watts: 

CPR (dB) = | 10 x LOG10 [P sum /P ref ] | 

8. Verify that the light source is Category-1 by comparing its CPR value to those given in 

Table A1. If the light source is Category-1, it is acceptable for attenuation testing. If the 

CPR value is too low, an alternate Category-1 light source must be obtained. Note that 

the source CPR may change depending on the core size of test jumper-1. For example, a 

source may provide Category 1 CPR into 50 µm fiber, but a higher category into 62.5 

µm fiber. 

TABLE A1 CATEGORY 1 COUPLED POWER RATIO (CPR) VALUES IN DB 

62.5 µm fiber 50 µm fiber 

850 nm Source 25 - 29 20 - 24 

1300 nm Source 21 - 25 16 - 20 


Appendix B 

Mandrel Wrap Prescriptions 

To remove high-order mode transient losses from multimode optical fiber measurements, the 

reference test jumper shall be wrapped in 5 non-overlapping turns around a smooth round mandrel 

(rod) during the reference calibration of the light source to the power meter and for all link segment 

attenuation measurements. See Figure 17. 

Figure 17 

The mandrel diameter shall be as specified in Table B1. Most testing will occur with the use of 

patch cords, i.e. jacketed fiber; therefore the larger madrels noted for 0.9 mm buffered fiber 

will be less commonly used than those for cordage. 

TABLE B1 MANDREL DIAMETERS FOR MULTIMODE OPTICAL FIBER 

Fiber Type Mandrel Diameter (mm) Cord + 

0.9 mm buffer 1.6 mm cordage 3 mm cordage 

Mandrel (mm) 

50 µm 

LazrSPEED 

62.5 µm 

OptiSPEED 

1 inch = 25.4 mm 

24.1 23.4 22 25 5 

19.1 18.4 17 20 5 

Number of 

Wraps 

Standards also discuss a similar requirement for single-mode fiber testing. In this case, only a 

single loop of 30 mm is required for the transmit patch cord. 


Appendix C: Encircled Flux Control 

(Optional for Field Testing) 

The mandrel wrap described in Appendix B is designed to remove the high order modes 

present when an optical source provides an OVERFILLED launch. However when the test source 

provides an UNDERFILLED launch, the mandrel wrap would not have an effect. To create a 

standard’s compliant output for both an underfilled or an overfilled launch, an encircled flux unit 

can be incorporated into the test set-up. 

IEC 61280-4-1 defines Encircled flux to support the testing of 50 um multimode fiber solutions 

at 850 nm that are likely to operate at data rates at 1G/s or higher. Although the standard 

was developed to support testing at the manufacturer, some test equipment providers are 

offering field encircled flux units. The unit could be incorporated within the test device, or as 

part of the test cord. The example below, provided by Fluke Networks, shows that an encircled 

flux device is used at the output of each test source. 

Figure 18 


Network 

At this time, CommScope does NOT require encircled flux testing in the field if mandrel 

wrapping is used. 


Test Instrument Data Sheet 

LIGHT SOURCE 

Manufacturer: Model: Serial Number: 

Spectral Width: 

850 nm: 

1300 nm: 

1310 nm: 

1550 nm: 

POWER METER 

Coupled Power Ratio (Category): 

850 nm: N/A 

1300 nm: N/A 

1310 nm: N/A 

1550 nm: N/A 

Manufacturer: Model: Serial Number: 


Link Attenuation Measurement Record for Power Meters 

Displaying Absolute Power Levels 

Test Personnel: Date: 

Light Source Test Location: Power Meter Test Location: 

Wavelength: Reference Power Measurement (Pref): Page of 

# Fiber Power Link Seg. Acceptable 

Identification (P ) Attn. (dB) Attn. (dB) 

sum 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

# Fiber Power Link Seg. Acceptable 

Identification (P ) Attn. (dB) Attn. (dB) 

sum 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 


www.commscope.com 

Visit our Web site or contact your local 

CommScope representative for more information. 

© 2011 CommScope, Inc. All rights reserved. 

All trademarks identified by ® 

or TM 

are registered trademarks 

or trademarks, respectively, of CommScope, Inc. 

This document is for planning purposes only and is not 

intended to modify or supplement any specifications or 

warranties relating to CommScope products or services. 

MI-25-1 09/11 

Link Attenuation Measurement Record for Power Meters 

Displaying Absolute Power Levels 

Test Personnel: Date: 

Light Source Test Location: Power Meter Test Location: 

Wavelength: Reference Power Measurement (Pref): Page of 

# Fiber 

Identification 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

Link Seg. Acceptable 

Attn. (dB) Attn. (dB) 

# Fiber 

Identification 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

Link Seg. Acceptable 

Attn. (dB) Attn. (dB)

Structured Connectivity Solutions Field Testing Guidelines for Fiber ...

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