1、 TIA DOCUMENT OFSTP-14 Optical Power Loss Measurements of Installed Multimode Fiber Cable Plant TIA-526-14-A (Revision of EIA/TIA-526-14) ANSI APPROVAL WITHDRAWN AUGUST 2003 AUGUST 1998 TELECOMMUNICATIONS INDUSTRY ASSOCIATION The Telecommunications Industry Association represents the communications
2、sector of Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-NOTICE TIA Engineering Standards and Publications are designed to serve the public interest through eliminating misunders
3、tandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for their particular need. The existence of such Publications shall not in any respect preclude any
4、 member or non-member of TIA from manufacturing or selling products not conforming to such Publications. Neither shall the existence of such Documents preclude their voluntary use by non-TIA members, either domestically or internationally. TIA DOCUMENTS TIA Documents contain information deemed to be
5、 of technical value to the industry, and are published at the request of the originating Committee without necessarily following the rigorous public review and resolution of comments which is a procedural part of the development of a American National Standard (ANS). Further details of the developme
6、nt process are available in the TIA Engineering Manual, located at http:/www.tiaonline.org/standards/sfg/engineering_manual.cfm TIA Documents shall be reviewed on a five year cycle by the formulating Committee and a decision made on whether to reaffirm, revise, withdraw, or proceed to develop an Ame
7、rican National Standard on this subject. Suggestions for revision should be directed to: Standards therefore, the user is responsible for determining whether the equipment temperature stability and optical power linearity is consistent with the accuracy and precision that is desired. NOTE: Non-linea
8、rity between the measured and incident optical power will introduce measurement error. Also, equipment with internal waveguides may exhibit measurement variability with varying modal conditions. 3.3 Test Jumpers The test jumper fibers shall have core diameter and numerical aperture nominally equal t
9、o those of the cable plant being measured. The jumpers shall be 1 to 5 meters (3.3 to 16.4 ft) long, and shall contain fibers with coatings that remove cladding light. Terminations shall be compatible with the light source and cable plant. 3.4 Miscellaneous Equipment To interface test jumpers with t
10、he cable plant, appropriate adapters may be required. Materials to clean the connections (such as reagent grade isopropyl alcohol, cotton swabs, and clean compressed air) may also be required. Equipment to inspect connectors for damage may be helpful. Copyright Telecommunications Industry Associatio
11、n Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-TIA-526-14-A 44. SAMPLING AND SPECIMENS The specifier shall describe, with appropriate documentation, which elements are to be measured. See Annex B. NOTE: Generally, the descript
12、ion will be one of the following cases: all cable segments, or a set of segments configured into point-to-point runs (through jumpers, patch panels, junction boxes, adapters, etc.). 5. PROCEDURE Measure the optical loss of the cable plant according to one of the following methods (For guidance in se
13、lecting a method, See Annex B): Method A - Two jumper reference (see 5.2) Method B - One jumper reference (see 5.3) Method C - Three jumper reference (see 5.4) 5.1 Precautions 5.1.1 To achieve consistent results, clean all connections and adapters at the optical test points prior to measurement. 5.1
14、.2 Unless otherwise specified in the Detail Specification, perform the following procedures at the wavelengths specified in 3.1.1. 5.1.3 Unless otherwise specified in the Detail Specification, perform the measurements bi-directionally. 5.1.4 All optical power measurements shall be recorded to one si
15、gnificant digit in the decimal place (e.g. -14.3 dBm, 10.1mW). 5.1.5 Reestablish the reference as necessary. Situations which might indicate a need to reestablish the reference include optical power changes, temperature fluctuations, a move to a different location, and jumper/adapter replacement due
16、 to degradation. 5.2 METHOD A: Two Jumper Reference 5.2.1 Connect test jumpers 1 and 2 between the light source and the optical power meter, as shown in Figure 1. Record the optical power, P1, which is the reference power measurement. Copyright Telecommunications Industry Association Provided by IHS
17、 under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-TIA-526-14-A 5TEST JUMPER 1LIGHTSOURCEOPTICAL POWEREQUIPMENTMEASUREMENTP1TEST JUMPER 2Figure 1. Reference Power Measurement for Method A 5.2.2 Separate the two jumpers at their point of connection
18、 without disturbing their attachment to the test equipment. Reattach test jumper 1 to one end of the cable plant to be measured, and test jumper 2 to the other end, as shown in Figure 2. TEST JUMPER 1 TEST JUMPER 2 LIGHT SOURCECABLE PLANT OPTICAL POWER EQUIPMENT MEASUREMENT 2 P Figure 2. Cable Plant
19、 Measurement for Methods A, B and C 5.2.3 Record the displayed optical power, P2, which is the test power measurement. 5.3 METHOD B: One Jumper Reference 5.3.1 Connect test jumper 1 between the light source and the optical power meter, as shown in Figure 3. Record the displayed optical power, P1, wh
20、ich is the reference power measurement. Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-TIA-526-14-A 6TEST JUMPER 1LIGHTSOURCEOPTICAL POWEREQUIPMENTMEASUREMENTP1Figure 3. Referenc
21、e Power Measurement for Method B 5.3.2 Disconnect test jumper 1 from the optical power meter without disturbing the connection to the light source, and attach it to the cable plant input. 5.3.3 Attach test jumper 2 to the output (far) end of the cable plant, and to the power meter, as shown in Figur
22、e 2. 5.3.4 Record the displayed optical power, P2, which is the test power measurement. 5.4 METHOD C: Three Jumper Reference 5.4.1 Connect test jumpers 1, 2, and 3 between the light source and the optical power meter, as shown in Figure 4. Record the displayed optical power, P1, which is the referen
23、ce power measurement. P TEST JUMPER 1 TEST JUMPER 2 LIGHT SOURCETESTOPTICAL POWER EQUIPMENT MEASUREMENT 1 JUMPER 3Figure 4. Reference Power Measurement for Method C 5.4.2 Disconnect separate test jumper 3 without removing the adapters from test jumpers 1 and 2 at their point of connection. Do not di
24、sturb the test jumpers at their attachment to the test equipment. 5.4.3 Attach test jumper 1 to the cable plant input and test jumper 2 to the output (far) end of the cable plant as shown in Figure 2. Test jumper 3 is not used in the test power measurement. 5.4.4 Record the displayed optical power,
25、P2, which is the test power measurement. Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-TIA-526-14-A 76. CALCULATIONS OR INTERPRETATION OF RESULTS 6.1 Calculation of results Calc
26、ulate the loss, L, for each measurement specified (at each wavelength, for each direction, for each cable plant segment), as follows: L = P1- P2 dB (1) for P1and P2in the same logarithmic units (e.g. dBm, dB) or L = - 10 log10 P2/ P1 dB (2) for P1and P2in watts. 6.2 Precision manufacturer and model
27、number. 8. SPECIFICATION INFORMATION The following information shall be specified in the document that invokes this test method. Refer to Annexes A there are other terms for similar testing within the intended scope of this document. This annex describes how to invoke this document for a specific pu
28、rpose. B.1 Guidance for Specifying Information. The following paragraphs refer to the subclause numbers in clause 8 of the main document, “SPECIFYING INFORMATION.” B.1.1 Test method to be used (8.1) Either Method A, B, or C must be specified in the document that invokes this test method. The choice
29、between methods is primarily a matter of how the optical loss in the equipment attachment jumpers or in the cable plant segment connection jumpers must be handled to adequately represent the loss as it will be experienced by the transmission equipment. Whichever method is chosen, it should be used c
30、onsistently throughout an installation. The differences among the three methods is in how the reference reading is taken, and this affects how the results should be interpreted. Figure B.1 depicts the measured values for the three methods. LIGHT SOURCECABLE PLANT OPTICAL POWER EQUIPMENT MEASUREMENT
31、2 P METHOD CMETHOD AMETHOD BJUMPERJUMPERFigure B.1 Cable Plant Measured Values for Methods A, B and C The Method A result includes one connection loss in the measurement of the cable plant in addition to all losses contained within the cable plant. Method A is the traditional insertion Copyright Tel
32、ecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-TIA-526-14-A 2loss measurement, and is consistent with FOTP-171 Method B, which measures fiber attenuation plus one connection loss in a jumper
33、cable. Method B result includes two connection losses in addition to all losses contained within the cable plant. Method B is appropriate when measuring cable segments with patch panels on both ends. Method B is the applicable method for testing a multimode cable plant adhering to ANSI/TIA/EIA-568A,
34、 “Commercial Building Telecommunications Cabling Standard”. The Method C result includes only the losses contained within the cable plant. This method is useful when measuring cable segments not utilizing patch panels, jumpers or adapters. Method C is also appropriate when testing through the system
35、 jumpers. When individually tested cable segments are linked together to form a path between two locations, it is desirable to calculate the end-to-end loss at the new link by summing the individual loss values of the cable segments. Depending on the test method utilized for the individual cable seg
36、ments (Method A, B, or C) and how the segments were joined (with patch panels and jumpers or directly interconnected without jumpers), the sum of the loss values may under or overestimate the actual loss. For spans with overestimated loss, subtract the typical insertion loss for the installed connec
37、tor type (usually 0.2 or 0.3 dB) for each connector pair that the sum of the links overestimated. For spans with underestimated loss, add the maximum (guaranteed) insertion loss for the installed connector type (usually 0.5 dB) for each connector pair that the sum of the links underestimated. Recall
38、 that Method A includes one connection pair loss with the losses in the cable plant, Method B includes two and Method C does not include any. If the corrected summed losses are close to the maximum link loss for the electronics, an end to end test should be completed for the new link. B.1.2 Elements
39、 of the cable plant to be measured (8.2) The elements of the cable plant to be measured usually depend on when the cable plant is tested. The initial installation of structured wiring systems is often performed without knowledge of the specifics of the optical transmission equipment, network configu
40、ration, or even the wavelength that will ultimately be used. For new construction, usually each cable segment is individually tested. This test could be invoked by language such as “Measure all cable plant segments per EIA/TIA-526-14, Method X, Source Category Y.” After the plant is installed, syste
41、m integrators may configure a point-to-point link consisting of multiple cable segments while installing the system electronics. The integrator may test through the cable segments, patch panels, jumpers and connectors to determine the loss that the electronics will see. Appropriate tests could be in
42、voked by language such as “Measure the following specified cable routes by EIA/TIA-526-14, Method X, Source Category Y,” together with documentation describing those routes. B.1.3 Light source characteristics (8.3) Copyright Telecommunications Industry Association Provided by IHS under license with
43、EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-TIA-526-14-A 3If no light source characteristics are specified, the values of 3.1.1, Table 1 apply. Any information specified overrides these values. Changes are discouraged in the interest of standardization. This p
44、rovision is not intended to accommodate non-conforming test sets. Some situations may justify different light source specifications: B.1.3.1 If the nominal wavelength of the transmission equipment is known, multiwavelength testing can be eliminated by specifying measurement at the transmission equip
45、ment wavelength, even if it is identical to one of the default values. B.1.3.2 If the transmission equipment is known to have a significantly different nominal center wavelength or spectral width, or a different type of optical source than the default conditions (such as an edge-emitting LED), an ap
46、propriately modified light source could be specified. B.1.3.3 If testing is intended to simulate extreme conditions, the source specifications need to be carefully considered. Multiple sources with characteristics at different extremes may be required. B.1.4 Measurement directions (8.5) Bi-direction
47、al testing is a default requirement of this document as it is the most conservative. Depending on the size and complexity of the cable plant and if OTDR testing is required, the specifier may delete the requirement for bi-directional measurements. The ANSI/TIA/EIA-568A, “Commercial Building Telecomm
48、unications Cabling Standard” specifies a one direction test. B.2 Accuracy Considerations The total cable plant loss measured by this test method may differ from that predicted by the sum of the individual component losses. It is typical of multimode optical components that some modes are more highly
49、 attenuated than others. The launched modal power and spectral distributions of the emitter interact with the modal and spectral attenuation characteristics of the cable plant and the modal coupling and spectral detection efficiencies of the receiver to produce the actual loss. Variability caused by these factors may be reduced, but not eliminated, by te
