MT-RJ OPTICAL FIBER SYSTEMS TESTING. Field Testing Made Easy

Transcription

1 MT-RJ OPTICL FIER SYSTEMS TESTING Field Testing Made Easy

2 TLE of CONTENTS Introduction...3 Recommended Test Components...4 Testing With Dual Sources and Detectors...5 Testing with a One Port Test Set...9 Conclusion

3 INTRODUCTION This paper describes field test procedures for MT-RJ optical fiber systems. TI/EI 568, Commercial uilding Telecommunications Cabling Standard, and ISO/IEC 11801, Generic Cabling for Customer Premises, currently recommend the one jumper reference method. This procedure is described in TI/EI , Optical Power Loss Measurements of Installed Multimode Fiber Cable Plant, and TI/EI-526-7, Measurement of Optical Power Loss of Installed Singlemode Fiber Cable Plant. oth procedures assume that the test equipment has the same connector interface as the patch panel and/or outlet. Today, new dual-fiber connector designs such as the MT-RJ are being installed, while the majority of test equipment in use today has single-fiber (such as ST or SC) ports. ccordingly, the one jumper reference measurement procedure must be slightly modified in order to test MT-RJ systems with non-mt-rj test sets. In years past, reference measurements were taken first primarily to verify that the one jumper used in the test is a good jumper. Once acceptable results were obtained, it was expected to maintain the connection on the source side throughout the testing procedure. While this is still good practice, the transition from one connection type on the test equipment to the MT-RJ connection requires disruption of the source connection. Fortunately, connector technology and tolerances have improved over the years, reducing connector-to-connector variability and the accompanying test variances. However, it is as important as ever to verify that the jumpers used for testing are good, quality jumpers. Two procedures are detailed in this document depending on the test set being used. One procedure is recommended for a test set with dual ports (one transmitter and one receiver); the other can be used for a test set with only one port available (either a source or a power meter). The recommended method for testing MT-RJ systems is to use a test set with MT-RJ test ports. Until these devices are readily available, dual-port power meters to test two fibers simultaneously, testing one fiber of the pair in one direction and the other fiber in the reverse direction is acceptable. Testing the MT-RJ system with a single port test set is less efficient (since only one direction can be tested at a time), but is still effective. The procedures below assume the test equipment has ST-compatible interfaces, however, the same procedure can be used for any single fiber interface (SC, FC). Different test sets have different features and procedures for storing references, so consult the test equipment manual for details. 3

4 RECOMMENDED TEST COMPONENTS Recommended MP MT-RJ Test Kits Fiber Type Connector Type Recommended Test Kit 62.5/125 Multimode ST /125 Multimode SC /125 Multimode ST /125 Multimode SC Singlemode ST Singlemode SC Each Test Kit Includes Quantity Description 2 MT-RJ dapter 1 ST-Style (Or SC) to MT-RJ (no pins) Patch Cord 1 MT-RJ to MT-RJ Patch Cord 2 Dual ST-Style (Or SC) to MT-RJ (with pins) Patch Cord 1 Carrying Case Label 1 Molded Case w/ Label 4

5 TESTING WITH DUL SOURCES ND DETECTORS Note: The first three steps of this procedure are designed to acquire a system reference and change the interface of the test equipment to MT-RJ. Record all power values in dbm and make sure the jumper fiber type matches that of the system under test. Step 1: Verify the test leads are in good condition and are continuous for all fiber paths. If there is doubt about the cable assembly, or if test results are erratic or unusually high, replace the cable assembly before conducting any testing. Replacing test leads once a reference value has been obtained requires a new reference measurement before further testing is completed. Step 2: Connect the pinned MT-RJ to ST jumper to one test unit (the MT-RJ in this jumper has pre-installed alignment pins unlike the MT-RJ connectors of standard MT-RJ which are pinless). Note: Do not make this MT-RJ to ST jumper using field-installable MT-RJ connectors these do not have the alignment pins necessary for good testing results. Connect the unpinned MT-RJ to ST jumper to the other test unit. Verify that the ST connectors are properly connected to the test equipment, i.e., connector to receiver and connector to transmitter. Do not disconnect these jumpers until testing is complete. MT-RJ Plug without Pins MT-RJ Plug with Pins Tx Rx Tx Rx 5

6 Step 3: Using one MT-RJ adapter, connect the two test jumpers. Record two power values, P 1 and P 2 - one for each fiber in the correct direction. These values are the reference values for subsequent testing. Note: record all power values in dbm and make sure the jumper fiber type matches that of the system under test. MT-RJ dapte r Tx Rx Tx Rx Step 4: Disconnect the unpinned MT-RJ from the adapter and insert this plug into the jack of one end of the system under test. Connect a standard (without pins) MT-RJ to MT-RJ jumper between the pinned MT-RJ test lead and the jack of the other system end. Record two power values, P 1 and P 2 - one for each fiber in the correct direction. Note: record all power values in dbm and make sure the jumper fiber type matches that of the system under test. Make sure you do not insert a pinned MT-RJ into the system under test you could damage the end face or bend the guide pins. Installed System Under Test Standard MT-RJ to MT-RJ Jumper MT-RJ dapter Tx Rx Tx 6

7 Step 5: Calculate system loss for each direction (each fiber) by subtracting the system power values from the system reference value in step 3. Record two P system power values, one for each fiber. Step 6: The system loss calculated in Step 5 must be less than or equal to the maximum allowable system losses published in the MP NETCONNECT 15-Year Performance Warranty and shown in the table below. The maximum allowable system loss can be calculated by summing the maximum cable attenuation, maximum connector attenuation and maximum splice loss for the link under test. Loss = Loss + Loss + system cable connector Loss splice Where: LOSS cable = ttenuation Coefficient [d/km] Cable Length [km] 1. Maximum ttenuation Coefficient for Cable nm for multimode (50/125 and 62.5/125) nm for multimode (50/125 and 62.5/125) for TI nm for multimode (50/125 and 62.5/125) for ISO nm for singlemode outside plant cable nm for singlemode outside plant cable nm for singlemode inside plant cable nm for singlemode inside plant cable 9. LOSS connector = Number of Connector Pairs Connector Loss [d] Maximum Connector Loss (each) d 13. LOSS Splice = Number of Splices Splice Loss [d] Maximum Splice Loss (each) d 7

8 The chart below contains the maximum allowable system loss for an installed system of maximum distance ( TI/EI-568 Standard ). The centralized cabling system listed has one splice in the telecommunications closet all others assume there are no splices. The calculated maximum allowable system loss for any installed system should be lower than or equal to the values in this chart. Cabling Subsystem System Length [meters] Multimode Maximum ttenuation [d] Singlemode 850 nm 1300 nm 1310 nm 1550 nm Horizontal Centralized (Splice) Centralized (Interconnect) uilding ackbone Campus ackbone Campus ackbone Notes: 1. dd 0.75 d to Horizontal or Centralized values if the optional consolidation point for Open Office Cabling is included in the installation. 2. TI/EI-568- only requires testing at one wavelength for Horizontal and Centralized networks. 3. TI/EI-568- only requires single directional testing, which is satisfied by this test procedure. 4. The horizontal channel maximum attenuation is set at 2.0 d per the standard. This chart below contains the maximum allowable system loss for an installed system of maximum distance ( ISO 11801/EN Standard ). The calculated maximum allowable system loss for any installed system should be lower than or equal to the values in this chart. Cabling Subsystem System Length [meters] Multimode Maximum ttenuation [d] Singlemode 850 nm 1300 nm 1310 nm 1550 nm Horizontal uilding ackbone 500 3, ,7 2,7 Campus ackbone ,6 3,6 3,6 Notes: 1. ISO / EN defines the maximum attenuation in the horizontal cabling system with the values above, even there is an optional consolidation point uncluded in the installation. 2. ISO / EN requires testing at one of the described wavelengths at least. 3. ISO / EN does not define Centralized Cabling yet. This will be done in the next revision. Please use the TI/EI-Values instead. 8

9 TESTING WITH ONE-PORT TEST SET The test procedure described below is to be used when only a one-port test set is available to do the testing. The first three steps of this procedure are to acquire a system reference and change the interface of the test equipment to MT-RJ. Step 1: Verify the test leads are in good condition and are continuous for all fiber paths. If there is doubt about the cable assembly, or if test results are erratic or unusually high, replace the cable assembly before conducting any testing. Replacing test leads once a reference value has been obtained requires a new reference measurement before further testing is completed. Note: record all power values in dbm and make sure the jumper fiber type matches that of the system under test. Step 2: Connect the pinned MT-RJ to ST jumper to one test unit (the MT-RJ in this jumper has pre-installed alignment pins unlike the MT-RJ connectors of standard MT-RJ which are pinless). Note: Do not make this MT-RJ to ST jumper using field-installable MT-RJ connectors these do not have the alignment pins necessary for good testing results. Connect the unpinned MT-RJ to ST jumper to the other test unit. Verify that the ST connectors are properly connected to the test equipment, i.e., connector to receiver and connector to transmitter. Do not disconnect these jumpers until testing is complete. MT-RJ Plug Without Pins MT-RJ Plug with Pins Tx Rx 9

10 Step 3: Using one MT-RJ adapter, connect the two test jumpers. Record the power value, P 1 for the fiber under test. This value is the reference value for subsequent testing in this direction. Note: record all power values in dbm and make sure the jumper fiber type matches that of the system under test. MT-RJ dapter Tx Rx Step 4: Disconnect the unpinned MT-RJ from the adapter and insert this plug into the jack of one end of the system under test. Connect a standard (without pins) MT-RJ to MT-RJ jumper between the pinned MT-RJ test lead and the jack of the other system end. Record the power values for this direction. Note: record all power values in dbm and make sure the jumper fiber type matches that of the system under test. Make sure you do not insert a pinned MT-RJ into the system under test you could damage the end face or bend the guide pins. Tx Installed System Under Test Standard MT-RJ to MT-RJ Jumper MT-RJ dapter Rx Step 5: Test each jack in this manner, recording power values for one fiber in each jack. Then test the remaining fibers in each jack by reversing the locations of the power source and power meter. It is not necessary to change or disconnect the test jumpers. Record power values for the remaining fibers in this direction. 10

11 Step 6: Calculate system loss for each fiber by subtracting the system power values from the system reference value in step 3. Record two P system power values for each jack. Step 7: The system loss calculated in Step 6 must be less than or equal to the maximum allowable system losses published in the MP NETCONNECT 15-Year Performance Warranty. Details are explained in Step 7 of the Dual-Port Test Procedure earlier in this document. 11

12 CONCLUSION The procedure described tests the MT-RJ system attenuation and verifies polarity using common test equipment interface connections. This procedure best simulates the results of the two-jumper reference recommended by TI/EI-568 and ISO/IEC while making allowances for the pin and no-pin variations of the MT-RJ connections. s the MT-RJ interface option becomes available on field testing equipment, the switch to TI/EI Method, one reference jumper, is strongly recommended. 12